Marine extinguishing agent using seawater and preparation method thereof

Abstract

This application relates to the field of fire extinguishing materials, and discloses a marine fire extinguishing agent that can be prepared using seawater and its preparation method. The fire extinguishing agent is composed of 75%–80% seawater, 9%–13% environmentally friendly nonionic surfactant, 6%–10% sodium lignosulfonate, 0.5%–2% tetrasodium glutamate diacetic acid, 0.5%–2% hydroxyethyl cellulose, and 0.2%–1% pH adjuster. During preparation, tetrasodium glutamate diacetic acid and sodium lignosulfonate are added to heated seawater to complex hardness ions. An alkaline adjuster is then added dropwise to induce the expansion of the polymer chains. Subsequently, the surfactant is added, followed by the addition of hydroxyethyl cellulose to construct a three-dimensional network. Finally, the system is cooled and the pH is adjusted to neutral using an acidic adjuster. This invention overcomes the problems of component salting out and polymer flocculation and precipitation caused by high salinity in seawater, improves the dispersion stability and penetration fire extinguishing efficiency of the product in a seawater matrix, and also possesses good biodegradability.

Description

Technical Field

[0001] This invention relates to the field of fire extinguishing materials technology, specifically to a marine fire extinguishing agent that can be prepared using seawater and its preparation method. Background Technology

[0002] Ocean-going vessels face relative scarcity of freshwater resources during voyages or maritime operations. In the event of a fire, directly drawing surrounding seawater as a fire-fighting water source to prepare water-based extinguishing agents is a standard emergency measure for shipboard fire suppression systems. Water-based extinguishing agents typically rely on their polymer components and surfactants to form a coating layer on the surface of the burning material or to provide wetting and penetration, thereby achieving the purpose of cooling and isolating oxygen to extinguish the fire.

[0003] However, seawater has a complex composition, containing high concentrations of inorganic salts and free hardness ions such as calcium and magnesium. When seawater is directly used to mix conventional water-based fire extinguishing agents, the high concentration of ions increases the ionic strength of the system, compressing the electric double layer of polymer molecules in the fire extinguishing agent and disrupting the extended state of the polymer chains. This change in the physicochemical environment easily triggers salting-out of the fire extinguishing agent components, causing flocculation and precipitation of polymeric substances. Phase separation in the system not only reduces the film-forming and wetting ability of the fluid, but the resulting solid precipitates can also easily clog fire pipelines and sprinkler heads, affecting the operational reliability of the fire protection system.

[0004] To overcome the salt precipitation and instability problems caused by high-salinity seawater, existing technologies often employ the addition of fluorocarbon surfactants to improve the salt resistance of fire extinguishing agents. While these fluorinated substances can maintain low surface tension in high-salinity environments, the carbon-fluorine bonds in their molecular structure are chemically stable and difficult to degrade by microorganisms in nature. Wastewater generated after ship firefighting or routine drills is usually discharged directly into the ocean, and long-term use and discharge of fluorinated fire extinguishing agents can cause persistent pollution to the marine ecosystem. Therefore, developing a marine fire extinguishing agent that can maintain physical dispersion stability in seawater and also possesses good biodegradability has become a key technological need to be addressed in this field. Summary of the Invention

[0005] The technical problem solved by this invention is that when existing marine fire extinguishing agents are prepared using seawater, the high concentration of free calcium and magnesium ions in the seawater will cause component salting out and polymer flocculation and precipitation, leading to the failure of the fire extinguishing agent and clogging of the nozzle. At the same time, traditional salt-resistant fire extinguishing agents often contain fluorocarbon surfactants, which are difficult to biodegrade and will damage the marine ecological environment.

[0006] To address the above problems, the present invention provides the following technical solution:

[0007] In a first aspect, the present invention provides a marine fire extinguishing agent that can be prepared using seawater, employing the following technical solution:

[0008] A marine fire extinguishing agent that can be prepared with seawater is made from the following raw materials by weight percentage:

[0009] Seawater 75%–80%;

[0010] Environmentally friendly nonionic surfactants: 9%–13%;

[0011] Sodium lignosulfonate 6%–10%;

[0012] Tetrasodium glutamate diacetic acid 0.5%–2%;

[0013] Hydroxyethyl cellulose 0.5%–2%;

[0014] pH adjuster 0.2%–1%.

[0015] By adopting the above technical solution, this invention improves the colloidal instability phenomenon in high-salt systems and enhances the salt-shedding dispersion resistance of fire extinguishing agents. Its mechanism of action is as follows:

[0016] The first step involves using tetrasodium glutamate diacetic acid as a chelating agent. The carboxyl anion in its molecular structure coordinates with free calcium and magnesium ions in seawater to form a water-soluble complex, which reduces the concentration of free hardness ions and weakens the compression and salting-out effects of hardness ions on polymer chains.

[0017] In the second step, sodium lignosulfonate is an anionic polyelectrolyte. Its sulfonic acid groups dissociate in water to provide electrostatic repulsion. Hydroxyethyl cellulose is hydrated by the hydroxyethyl groups on the main chain to form a three-dimensional network structure. Environmentally friendly nonionic surfactants are interspersed in this three-dimensional network and are not affected by changes in the ionic strength of the system. Their hydrophilic groups form hydrogen bonds with water molecules, which thickens the outer hydration layer of the dispersed phase. The three components work synergistically to achieve physical isolation and dispersion of the effective substances in the seawater system by utilizing electrostatic repulsion and steric hindrance effects.

[0018] Preferably, the marine fire extinguishing agent is made from the following raw materials by weight percentage: 78.5% seawater, 11% environmentally friendly nonionic surfactant, 8% sodium lignosulfonate, 1% tetrasodium glutamate diacetic acid, 1% hydroxyethyl cellulose, and 0.5% pH adjuster.

[0019] By adopting the above technical solution, this specific ratio allows the components in the system to work in balance, reducing the apparent viscosity of the extinguishing agent in seawater and improving its anti-sedimentation performance.

[0020] Preferably, the environmentally friendly nonionic surfactant is composed of alkyl glycoside and ethylene oxide-propylene oxide block polyether, and the mass ratio of the two is 1:2 to 2:1.

[0021] By employing the above technical solution, alkyl glycosides provide surface activity and environmental biodegradability, while ethylene oxide-propylene oxide block polyethers provide phase change regulation and anti-foaming properties. The combination of these two components reduces the surface tension of the system and improves the wetting and penetration rate of the extinguishing agent onto combustibles.

[0022] Preferably, the environmentally friendly nonionic surfactant is prepared by the following steps: the alkyl glycoside is added to a premixing vessel and heated. When the temperature rises to 45°C, the ethylene oxide-propylene oxide block polyether is added. The mixture is stirred at a constant temperature of 45°C until it is completely miscible and forms a uniform and transparent liquid phase. The mixture is then cooled to room temperature to obtain the final product.

[0023] By adopting the above technical solution, the molecules of the two surfactants are entangled and evenly distributed, thus avoiding local phase separation during the compounding process.

[0024] Preferably, the seawater is natural seawater or artificial seawater; the pH adjuster is an aqueous solution of sodium hydroxide and an aqueous solution of citric acid.

[0025] By adopting the above technical solutions, the fire extinguishing agent can be adapted to different seawater qualities. The pH value of the system can be adjusted by the above acid-base combination. Without introducing interfering anions, the citrate ions provide auxiliary complexation.

[0026] Secondly, the present invention provides a method for preparing a marine fire extinguishing agent that can be prepared using seawater, comprising the following steps:

[0027] S1: According to the component ratio of the marine fire extinguishing agent, weigh seawater, environmentally friendly nonionic surfactant, sodium lignosulfonate, tetrasodium glutamate diacetic acid, hydroxyethyl cellulose and pH adjuster respectively, wherein the pH adjuster is composed of alkaline adjuster and acidic adjuster.

[0028] S2: Pour the weighed seawater into the main reactor equipped with a heating jacket and mechanical stirring, and turn on the heating to raise the water temperature;

[0029] S3: While stirring, add the weighed tetrasodium glutamate diacetic acid and sodium lignosulfonate in sequence, and stir at a constant temperature so that the tetrasodium glutamate diacetic acid complexes the free hardness ions.

[0030] S4: Under continuous stirring, the alkaline regulator is slowly added dropwise to raise the pH of the system to an alkaline environment to induce the molecular chains to unfold. Then, the weighed environmentally friendly nonionic surfactant is added and stirred at a constant temperature.

[0031] S5: While maintaining the stirring state, add the weighed hydroxyethyl cellulose into the main reactor and stir at a constant temperature until the powder is completely swollen and forms a three-dimensional network;

[0032] S6: Turn off the heating and cool down, slowly add the acidic regulator to bring the pH of the system back to neutral, continue stirring and filter to obtain the finished marine fire extinguishing agent;

[0033] The total mass of the alkaline regulator consumed in S4 and the acidic regulator consumed in S6 is equal to the total mass of the pH regulator weighed in S1.

[0034] By adopting the above technical solution, the changes in the feeding sequence and the pH value of the system were controlled, thus mitigating the impact of high-salinity water on polymer dissolution and hydration. The preparation mechanism is as follows:

[0035] The first step involves adding tetrasodium glutamate diacetic acid in the S3 stage beforehand. This preferentially complexes free calcium and magnesium ions in seawater before other polymer components form their spatial configurations, preventing polymer chains from agglomerating due to the bridging effect of metal ions.

[0036] The second step, in stage S4, involves adding an alkaline regulator to increase the pH of the system, causing the acidic groups of sodium lignosulfonate to dissociate, and the polymer chains to unwind under the repulsion of like charges. In stage S5, the unwinding system environment provides free volume for the swelling of hydroxyethyl cellulose, promoting the hydration of its main chain and the construction of a uniform three-dimensional network.

[0037] The third step involves cooling the system in stage S6 and using an acidic regulator to bring the pH back to neutral, reducing the risk of strong alkali corrosion while fixing the polymer network state to obtain a stable finished fluid.

[0038] Preferably, in step S2, heating is turned on to raise the water temperature to 45-50°C; in step S3, the stirring speed is 200 rpm and the constant temperature stirring time is 15 minutes.

[0039] By adopting the above technical solution and providing suitable temperature and stirring shear conditions, the complexation reaction process of tetrasodium glutamate diacetic acid was accelerated.

[0040] Preferably, in step S4, the alkaline regulator is a 25wt% sodium hydroxide aqueous solution. The sodium hydroxide aqueous solution is added dropwise to raise the pH value of the system to 9.8-10.5, and the system is stirred at a constant temperature of 45-50°C for 20 minutes.

[0041] By adopting the above technical solution, the pH value is controlled within the alkaline range, which promotes the dissociation and extension of molecular chain segments and reduces the impact of excessive alkalinity on the hydrolytic degradation of surfactants.

[0042] Preferably, in step S5, the hydroxyethyl cellulose is added slowly and evenly, and the constant temperature stirring time is 30 minutes until there are no lumps.

[0043] By adopting the above technical solution, the rapid swelling of hydroxyethyl cellulose powder upon contact with water, which forms gel clumps encapsulating the dry powder, is prevented, thus ensuring the uniformity of the three-dimensional network.

[0044] Preferably, in step S6, the heating is turned off and the temperature is allowed to drop naturally to 25°C. The acidity regulator is a 40wt% citric acid aqueous solution. The citric acid aqueous solution is added dropwise to adjust the pH value of the system back to 6.5-7.5, and stirring is continued for 20 minutes.

[0045] By adopting the above technical solution, the system temperature is gradually reduced, ensuring the stability of the network structure of the polymer material and improving the physicochemical stability of the final product.

[0046] This invention provides a marine fire extinguishing agent that can be prepared using seawater and its preparation method. It has the following beneficial effects:

[0047] 1. This invention introduces tetrasodium glutamate diacetic acid into the formulation, which preferentially coordinates with free calcium and magnesium ions in seawater. Combined with the three-dimensional network structure constructed by sodium lignosulfonate and hydroxyethyl cellulose in the system, the compression effect of hardness ions on polymer chain segments is reduced from the aspects of steric hindrance and electrostatic repulsion. This improves the problem of salting out and polymer flocculation and precipitation of components in high-salt systems, and improves the dispersion stability of fire extinguishing fluid in seawater matrix.

[0048] 2. This invention uses alkyl glycosides and ethylene oxide-propylene oxide block polyethers to form an environmentally friendly nonionic surfactant. This component is interspersed in the three-dimensional network of polymers, which reduces the surface tension of the system and improves the wetting and penetration rate of fire extinguishing agent fluids on combustibles such as wood stacks. At the same time, it avoids the defects of traditional fluorinated surfactants that are difficult to degrade, giving the product good environmental biodegradability.

[0049] 3. The present invention employs a dynamic pH adjustment process during preparation. First, an alkaline regulator is added to create an alkaline environment in the system, promoting the dissociation and expansion of polymer chains, providing space for the uniform hydration of hydroxyethyl cellulose, and preventing powder swelling and clumping. Subsequently, an acidic regulator is used during the cooling stage to restore the system to neutral, fixing the fluid's network structure, reducing the corrosion risk of the finished product, and ensuring the physicochemical stability of the fire extinguishing agent and the safety of the supporting equipment. Attached Figure Description

[0050] Figure 1 The following is a comparison chart of the rheological dispersion performance of the fluids in each group in Test Example 1 of the present invention, wherein: (a) is a histogram comparing the apparent viscosity of each group of fluids after static degassing, and (b) is a comparison chart of the agglomeration rate of the retained material and the time required for complete hydration.

[0051] Figure 2The following is a comparison chart of the clarity and sedimentation of each group of fluids in Test Example 2 of the present invention, wherein: (a) is a histogram of turbidity comparison of each group of fluids during the alkaline induction period, and (b) is a histogram of mass fraction of centrifuged sediment of finished fluids.

[0052] Figure 3 The following is a comparison chart of the salting-out resistance and wetting penetration performance of the fluids in each group in Test Example 3 of the present invention, wherein: (a) is a histogram comparing the surface tension of each component fluid, and (b) is a comparison chart of the settling time and 600nm transmittance of standard pure cotton unsizing canvas.

[0053] Figure 4 The following is a comparison chart of the comprehensive performance of the basic physicochemical indicators of the finished products in each group in Test Example 4 of the present invention, wherein: (a) is a comparison histogram of apparent viscosity of fluids, (b) is a comparison histogram of centrifugal solid precipitation rate, and (c) is a comparison histogram of surface tension of fluids.

[0054] Figure 5 The following is a comparison chart of the fire extinguishing efficiency and core cooling dynamics of the fluid entities in each group in Test Example 5 of the present invention, wherein: (a) is a monitoring curve of the dynamic decrease of the core temperature of the woodpile over time during the fire extinguishing spray process, and (b) is a comparison histogram of the fire extinguishing time of the fluid in each group.

[0055] Figure 6 The flowchart illustrates the preparation method of fire extinguishing fluid in a high-salt system provided by this invention. Detailed Implementation

[0056] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0057] This invention provides a marine fire extinguishing agent that can be prepared using seawater. The main raw materials and reagents used in the following examples and comparative examples are as follows. Unless otherwise specified, all reagents are commercially available analytical grade or higher grade products.

[0058] The solvent used in the embodiments and comparative examples of this invention is seawater, which can be natural seawater or artificially prepared seawater. Artificial seawater is prepared by deionized water with 3.5 wt% sodium chloride (CAS No. 7647-14-5), 0.13 wt% anhydrous magnesium chloride (CAS No. 7786-30-3) and 0.04 wt% anhydrous calcium chloride (CAS No. 10043-52-4).

[0059] The alkyl glycoside (CAS No. 110615-47-9) in the formula has a fatty alcohol carbon chain length of 8 to 14 carbon atoms and an average degree of polymerization of 1.2 to 1.6.

[0060] The weight-average molecular weight of ethylene oxide-propylene oxide block polyether (CAS No. 9003-11-6) is 2000 to 4000, and the hydrophilic-lipophilic balance value is 8 to 11.

[0061] Sodium lignosulfonate (CAS No. 8061-51-6) has a weight-average molecular weight of 5,000 to 10,000 and a degree of sulfonation of 0.8 to 1.5 mmol / g;

[0062] The degree of molar substitution of hydroxyethyl cellulose (CAS No. 9004-62-0) is 1.5 to 2.5, and its 2 wt% aqueous solution has a Brookfield viscosity of 30,000 to 100,000 mPa·s at 20 °C.

[0063] The corrosion inhibitor used is tetrasodium glutamate diacetic acid (CAS No. 51981-21-6).

[0064] Sodium hydroxide (CAS No. 1310-73-2) and citric acid (CAS No. 77-92-9) are both commercially available common reagents. Before use, prepare 25wt% sodium hydroxide aqueous solution and 40wt% citric acid aqueous solution respectively with deionized water for later use.

[0065] The molecular structure of the above components can be clearly defined by their chemical names or corresponding CAS numbers. For substances that can be identified by their chemical structural characteristics, redundant descriptions of their microstructures will not be provided here.

[0066] Preparation Example 1:

[0067] This preparation example provides a method for preparing a marine fire extinguishing agent that can be prepared using seawater, including the following steps:

[0068] In a premixing vessel equipped with a constant temperature water bath and a mechanical stirring device, alkyl glycosides and ethylene oxide-propylene oxide block polyethers are weighed at a mass ratio of 1:1.

[0069] First, add the alkyl glycoside to the reactor and turn on the heating. When the temperature inside the reactor rises to 45°C, add the ethylene oxide-propylene oxide block polyether.

[0070] The stirring speed was set to 200 rpm, and the mixture was stirred at a constant temperature of 45°C for 30 minutes until the two substances were completely miscible and formed a uniform and transparent liquid phase. Heating and stirring were stopped, and the mixture was cooled to room temperature and then sealed for later use, thus obtaining an environmentally friendly nonionic surfactant with a mass ratio of 1:1.

[0071] Preparation Example 2:

[0072] This preparation example provides a method for preparing a marine fire extinguishing agent that can be prepared using seawater, including the following steps:

[0073] In a premixing vessel equipped with a constant temperature water bath and a mechanical stirring device, alkyl glycosides and ethylene oxide-propylene oxide block polyethers are weighed at a mass ratio of 1:2.

[0074] First, add the alkyl glycoside to the reactor and turn on the heating. When the temperature inside the reactor rises to 45°C, add the ethylene oxide-propylene oxide block polyether.

[0075] The stirring speed was set to 200 rpm, and the mixture was stirred at a constant temperature of 45°C for 30 minutes until the two substances were completely miscible and formed a uniform and transparent liquid phase. Heating and stirring were stopped, and the mixture was cooled to room temperature and then sealed for later use, thus obtaining an environmentally friendly nonionic surfactant with a mass ratio of 1:2.

[0076] Preparation Example 3:

[0077] This preparation example provides a method for preparing a marine fire extinguishing agent that can be prepared using seawater, including the following steps:

[0078] In a premixing vessel equipped with a constant temperature water bath and a mechanical stirrer, alkyl glycosides and ethylene oxide-propylene oxide block polyethers are weighed at a mass ratio of 2:1. The alkyl glycosides are first added to the vessel, heating is started, and when the temperature inside the vessel reaches 45°C, the ethylene oxide-propylene oxide block polyethers are added.

[0079] The stirring speed was set to 200 rpm, and the mixture was stirred at a constant temperature of 45°C for 30 minutes until the two substances were completely miscible and formed a uniform and transparent liquid phase. Heating and stirring were stopped, and the mixture was cooled to room temperature and then sealed for later use, thus obtaining an environmentally friendly nonionic surfactant with a mass ratio of 2:1.

[0080] Example 1:

[0081] This embodiment provides a marine fire extinguishing agent that can be prepared using seawater and its preparation method, including the following steps:

[0082] Step 1: Weigh out 78.5% natural seawater, 11% environmentally friendly nonionic surfactant, 8% sodium lignosulfonate, 1% tetrasodium glutamate diacetic acid, 1% hydroxyethyl cellulose and 0.5% pH adjuster by weight percentage. The environmentally friendly nonionic surfactant is prepared using Preparation Example 1. The pH adjuster is a combination of 25 wt% sodium hydroxide aqueous solution and 40 wt% citric acid aqueous solution.

[0083] Step 2: Pour the weighed natural seawater into the main reactor equipped with a heating jacket and mechanical stirring, and turn on the heating to raise the water temperature to 45°C;

[0084] Step 3: Add tetrasodium glutamate diacetic acid and sodium lignosulfonate sequentially at a stirring speed of 200 rpm, and stir at a constant temperature for 15 minutes;

[0085] Step 4: Slowly add 25wt% sodium hydroxide aqueous solution dropwise under continuous stirring to raise the pH value of the system to 10.0, then add environmentally friendly nonionic surfactant, and stir at 45℃ for 20 minutes.

[0086] Step 5: While maintaining stirring, slowly and evenly sprinkle hydroxyethyl cellulose into the main reactor, and stir at a constant temperature for 30 minutes until the powder is completely swollen and free of lumps;

[0087] Step 6: Turn off the heating and let it cool naturally to 25°C. Slowly add 40wt% citric acid aqueous solution to adjust the pH of the system back to 7.0. Continue stirring for 20 minutes. After filtration, fill the package to obtain the finished product.

[0088] The total mass of the sodium hydroxide aqueous solution and citric acid aqueous solution consumed in steps four and six is ​​equal to the total mass of the pH adjuster weighed.

[0089] Example 2:

[0090] This embodiment provides a marine fire extinguishing agent that can be prepared using seawater and its preparation method, including the following steps:

[0091] Step 1: Weigh out 78.5% natural seawater, 11% environmentally friendly nonionic surfactant, 8% sodium lignosulfonate, 1% tetrasodium glutamate diacetic acid, 1% hydroxyethyl cellulose, and 0.5% pH adjuster by weight percentage. The environmentally friendly nonionic surfactant is prepared using Preparation Example 2. The pH adjuster is a combination of 25 wt% sodium hydroxide aqueous solution and 40 wt% citric acid aqueous solution.

[0092] Step 2: Pour the weighed natural seawater into the main reactor equipped with a heating jacket and mechanical stirring, and turn on the heating to raise the water temperature to 50°C;

[0093] Step 3: Add tetrasodium glutamate diacetic acid and sodium lignosulfonate sequentially at a stirring speed of 200 rpm, and stir at a constant temperature for 15 minutes;

[0094] Step 4: Slowly add 25wt% sodium hydroxide aqueous solution dropwise under continuous stirring to raise the pH value of the system to 10.5, then add environmentally friendly nonionic surfactant, and stir at 50℃ for 20 minutes.

[0095] Step 5: While maintaining stirring, slowly and evenly sprinkle hydroxyethyl cellulose into the main reactor, and stir at a constant temperature for 30 minutes until the powder is completely swollen and free of lumps;

[0096] Step 6: Turn off the heating and let it cool naturally to 25°C. Slowly add 40wt% citric acid aqueous solution to adjust the pH of the system back to 6.5. Continue stirring for 20 minutes. After filtration, fill the package to obtain the finished product.

[0097] The total mass of the sodium hydroxide aqueous solution and citric acid aqueous solution consumed in steps four and six is ​​equal to the total mass of the pH adjuster weighed.

[0098] Example 3:

[0099] This embodiment provides a marine fire extinguishing agent that can be prepared using seawater and its preparation method, including the following steps:

[0100] Step 1: Weigh out 78.5% artificial seawater, 11% environmentally friendly nonionic surfactant, 8% sodium lignosulfonate, 1% tetrasodium glutamate diacetic acid, 1% hydroxyethyl cellulose, and 0.5% pH adjuster by weight percentage. The environmentally friendly nonionic surfactant is prepared using Preparation Example 3, and the pH adjuster is a combination of 25 wt% sodium hydroxide aqueous solution and 40 wt% citric acid aqueous solution.

[0101] Step 2: Pour the weighed artificial seawater into the main reactor equipped with a heating jacket and mechanical stirring, and turn on the heating to raise the water temperature to 48°C;

[0102] Step 3: Add tetrasodium glutamate diacetic acid and sodium lignosulfonate sequentially at a stirring speed of 200 rpm, and stir at a constant temperature for 15 minutes;

[0103] Step 4: Slowly add 25wt% sodium hydroxide aqueous solution dropwise under continuous stirring to raise the pH value of the system to 9.8, then add environmentally friendly nonionic surfactant, and stir at 48℃ for 20 minutes.

[0104] Step 5: While maintaining stirring, slowly and evenly sprinkle hydroxyethyl cellulose into the main reactor, and stir at a constant temperature for 30 minutes until the powder is completely swollen and free of lumps;

[0105] Step 6: Turn off the heating and let it cool naturally to 25°C. Slowly add 40wt% citric acid aqueous solution to adjust the pH of the system back to 7.5. Continue stirring for 20 minutes. After filtration, fill the package to obtain the finished product.

[0106] The total mass of the sodium hydroxide aqueous solution and citric acid aqueous solution consumed in steps four and six is ​​equal to the total mass of the pH adjuster weighed.

[0107] Comparative Example 1:

[0108] Compared with Example 1, the difference is that the operation of adding sodium hydroxide aqueous solution to raise the pH to 10.0 in step four and the operation of adding citric acid aqueous solution to adjust the pH in step six are omitted. That is, no pH adjuster is added throughout the process, and the system is stirred and mixed at its natural pH. All other aspects are the same.

[0109] Comparative Example 2:

[0110] Compared with Example 1, the difference is that tetrasodium glutamate diacetic acid (corrosion inhibitor) is not added to the formula, and 1% of its weight is replaced by an equal amount of natural seawater, while the rest are the same.

[0111] Comparative Example 3:

[0112] Compared with Example 1, the difference is that the 11% environmentally friendly nonionic surfactant (the compound prepared in Preparation Example 1) in step one is completely replaced with an equal mass of a single alkyl glycoside, and the rest are the same.

[0113] Test Example 1:

[0114] From the preparation processes of Examples 1-3 and Comparative Example 1, 1000g of the finished fluid samples were taken after the addition of cellulose and the final pH adjustment and stirring were completed.

[0115] The sample to be tested was placed in a constant temperature water bath at 20℃ and allowed to stand for 2 hours to remove bubbles. The apparent viscosity of the system was measured using a rotational viscometer. A No. 4 rotor was selected and the rotation speed was set to 60 rpm. After the reading stabilized, the data was recorded. The average value was taken after 3 consecutive measurements.

[0116] After the viscosity test is completed, the sample is poured and filtered through a pre-weighed 80-mesh standard stainless steel test sieve at a uniform speed. The residue on the sieve is collected and washed three times with anhydrous ethanol to remove residual moisture and surfactants. The washed residue is then placed in a vacuum drying oven at 60°C and dried to constant weight. The percentage of the dry weight of the residue to the total theoretical mass of hydroxyethyl cellulose added in the formulation is calculated and recorded as the agglomeration rate.

[0117] The cellulose feeding and hydration process of each group was reproduced in an independent 500mL jacketed glass reactor. A top-mounted stirrer was used in conjunction with an online torque sensor to record the time from when the hydroxyethyl cellulose powder came into contact with the liquid surface until the fluctuation of the stirring torque reading was less than 2% and reached the plateau value. This time period was recorded as the time for complete hydration.

[0118] Table 1. Rheological dispersion performance test data of the examples and comparative examples.

[0119] Group Apparent viscosity ( ) Clumping rate (%) Time required for complete hydration (min) Example 1 843.6 0.45 27.5 Example 2 861.2 0.38 31.2 Example 3 829.8 0.52 26.8 Comparative Example 1 315.4 62.14 142.5

[0120] Based on the data in Table 1 and its appendix Figure 1The apparent viscosity distribution of Examples 1-3 ranges from 829.8 to 861.2. Between these values, the clumping rate was less than 0.6%, and the time required for complete hydration was controlled between 26.8 and 31.2 minutes.

[0121] This indicates that under high-salt conditions, the fluid system formed in the above embodiments possesses stable rheological characteristics, and the thickener exhibits high solubility and dispersibility. The apparent viscosity of Comparative Example 1 is 315.4. This is lower than the conventional level of the example, with an agglomeration rate of 62.14% and a complete hydration time extended to 142.5 minutes.

[0122] Analysis of the reaction conditions during the preparation process shows that no pH adjustment was introduced in Comparative Example 1, and the system was in its natural pH state.

[0123] High concentrations of inorganic salt ions squeeze the hydration layer surrounding the hydroxyethyl cellulose molecules, causing the powder particles to absorb water and swell upon contact with the water surface, forming a polymeric gel film.

[0124] The gel membrane hinders further hydration of undissolved particles inside, resulting in a high agglomeration rate on a macroscopic scale.

[0125] A large amount of cellulose was trapped on the screen in the form of dry powder clusters and failed to be released into the liquid phase to participate in the construction of the three-dimensional network structure, resulting in a lower apparent viscosity of the final fluid.

[0126] In this example, the pH of the system was raised to the alkaline range before cellulose was added, causing a conformational change in sodium lignosulfonate molecules and the molecular chains to unfold.

[0127] The extended lignin molecules form a physical isolation layer on the surface of dispersed hydroxyethyl cellulose particles through electrostatic repulsion and steric hindrance.

[0128] The isolation layer restricts the instantaneous penetration of water into the interior of cellulose particles, thus slowing down the formation rate of the surface gel film.

[0129] During the process of adjusting the pH to neutral, the lignin molecular chains shrink, and the cellulose exposes swelling sites and binds with water molecules, achieving uniform hydration.

[0130] The data on the time required for complete hydration reflects that the process controls the dissolution time of cellulose to about 30 minutes, eliminating the occurrence of gel aggregation and maintaining the physical stability of the extinguishing agent system.

[0131] Test Example 2:

[0132] In the preparation processes of Examples 1-3 and Comparative Example 2, after completing the dropwise addition of sodium hydroxide aqueous solution in step four and the corresponding constant-temperature stirring, 150 mL of liquid phase sample was drawn from the main reaction vessel and recorded as the induction period sample. The extraction process maintained the original temperature of the system and did not exceed 50°C.

[0133] Immediately transfer the collected induction-phase samples to a measuring cuvette and determine the turbidity of the fluid using a portable turbidity meter. Zero-calibrate the instrument before each measurement, record the data after the reading stabilizes, and perform three consecutive parallel measurements, taking the arithmetic mean.

[0134] After each group completes all the preparation processes according to the original steps and obtains the final product, 100g of the finished product fluid is accurately weighed and injected into a centrifuge tube.

[0135] Place the centrifuge tubes symmetrically inside the rotor of a benchtop high-speed centrifuge, set the centrifuge speed to 4500 rpm, and run it continuously for 20 minutes. After the centrifuge cycle is complete, remove the centrifuge tubes and discard the supernatant.

[0136] Collect the solid precipitate retained at the bottom of the tube, add a small amount of deionized water and centrifuge twice to remove surface salts.

[0137] The washed precipitate, along with its container, was placed in a 50°C vacuum drying oven and dried to constant weight. The mass of the obtained dry matter was weighed, and its ratio to the total mass of the finished product was calculated.

[0138] Table 2. Clarity and Sedimentation Test Data of Examples and Comparative Examples

[0139] Group Turbidity during alkaline induction period (NTU) Mass fraction of centrifuged precipitate (%) Example 1 16.4 0.03 Example 2 14.8 0.05 Example 3 17.2 0.04 Comparative Example 2 841.7 2.19

[0140] Based on the data in Table 2 and the appendix Figure 2 In Examples 1-3, the turbidity during the alkaline induction period was between 14.8 and 17.2 NTU, and the mass fraction of the centrifuged precipitate in the finished product was in the low range of 0.03% to 0.05%.

[0141] Comparative Example 2 had a turbidity of up to 841.7 NTU at the same stage, and the mass fraction of centrifuged precipitate in its finished product reached 2.19%.

[0142] The seawater system contains high concentrations of soluble calcium and magnesium ions. Step four of the preparation process requires the addition of an aqueous sodium hydroxide solution to raise the pH of the system to 9.8 or higher.

[0143] Increased alkalinity in the environment disrupts the original dissolution balance of inorganic ions. Free calcium and magnesium ions combine with hydroxide ions or dissolved carbonate ions in the solution to form magnesium hydroxide and calcium carbonate microcrystals that are difficult to dissolve in water.

[0144] In Comparative Example 2, without the addition of tetrasodium glutamate diacetic acid, a large number of microcrystals rapidly nucleated and grew during the high-temperature alkaline induction period, forming a group of suspended particles that blocked light propagation, resulting in extremely high readings on the turbidimeter. After high-speed centrifugation, the suspended inorganic particles aggregated and settled due to density differences, resulting in a high proportion of solid precipitates.

[0145] In this example, tetrasodium glutamate diacetic acid was introduced at the initial stage of preparation. This compound contains multiple electron-donating groups, and the amino nitrogen atom and carboxyl oxygen atom in its structure undergo coordination complexation reactions with free calcium and magnesium ions.

[0146] Metal ions are encased in a three-dimensional chelate ring formed inside the molecule, losing their chemical activity to participate in inorganic precipitation reactions.

[0147] Coordination effects manifest as threshold scale inhibition at the macroscopic level, interfering with the regular arrangement of inorganic salt lattices and the crystal growth process.

[0148] Turbidity and precipitation data confirmed that, under conditions with chelation intervention, the system did not undergo phase separation reaction under drastic acid-base changes, and the fluid components maintained a uniform and stable physical state throughout the entire process.

[0149] Test Example 3:

[0150] Take 500 mL of each of the finished fluids prepared in Examples 1-3 and Comparative Example 3 as test samples. Place the samples in a 25°C constant temperature oven and let them stand for 24 hours to allow the system to reach thermodynamic equilibrium.

[0151] The surface tension of each group of samples was determined using a fully automated surface tension meter, employing the platinum plate method. Before testing, the platinum plates were alternately rinsed with deionized water and anhydrous ethanol, and the surface was treated with an alcohol lamp flame. The samples were placed on the sample stage, and the test temperature was set to 25℃. The instrument automatically recorded the mechanical changes upon liquid contact. Each group of samples was measured independently five times, and the arithmetic mean was taken after removing outliers with significant deviations.

[0152] Cut a standard pure cotton unsizing canvas disc with a diameter of 30mm for sedimentation testing. Add 150mL of the sample to be tested to a 250mL beaker. Use tweezers to place the canvas disc horizontally on the liquid surface of the beaker and start the stopwatch the instant it is placed.

[0153] Observe the capillary permeation process of the liquid phase between the fibers, record the time from when the bottom of the canvas comes into contact with the liquid surface until it is completely wetted and sinks to the bottom of the beaker, and calculate the average time by conducting five parallel tests.

[0154] The degree of salting-out turbidity within a fluid was quantitatively characterized using a UV-Vis spectrophotometer. The sample was slowly injected into a quartz cuvette with a path length of 10 mm, avoiding the introduction of air bubbles. Deionized water was used as the reference solution, and the test wavelength was set to 600 nm. The transmittance of the sample was then read.

[0155] Table 3. Test data on salt-curing resistance and wetting penetration of the examples and comparative examples.

[0156] Group Surface tension (mN / m) Canvas settling time (s) 600nm transmittance (%) Example 1 26.4 8.3 98.1 Example 2 25.7 7.6 97.4 Example 3 27.2 9.1 98.6 Comparative Example 3 39.8 63.5 41.2

[0157] Based on the data in Table 3 and the appendix Figure 3 The surface tension of Examples 1-3 is between 25.7 and 27.2 mN / m, the canvas settling time is between 7.6 and 9.1 seconds, and the 600nm transmittance remains at a high level of over 97%.

[0158] The surface tension of Comparative Example 3 increased to 39.8 mN / m, the canvas settling time increased to 63.5 seconds, and the light transmittance decreased significantly to 41.2%.

[0159] The solubility of surfactants in solution is directly affected by the ionic strength of inorganic salts.

[0160] The formulation system matrix is ​​natural or artificial seawater. The large amount of sodium, calcium, magnesium and chloride ions in seawater compete with water molecules through hydration, compressing the hydration layer around the polar head group of the surfactant.

[0161] Comparative Example 3 uses only a single alkyl glycoside, whose hydrophilic group's hydration ability is weakened under high ionic strength conditions, and intermolecular van der Waals forces become dominant, causing surfactant molecules to desolvate and precipitate from the liquid phase.

[0162] On a macroscopic level, the precipitated surfactants aggregate to form micron-sized suspended droplets or flocculent phases, which strongly scatter transmitted light, causing a sharp drop in transmittance.

[0163] Because a large number of active ingredients are free outside the aqueous phase, the gas-liquid interface cannot maintain a dense surfactant monolayer, and the surface free energy cannot be effectively reduced, resulting in increased surface tension.

[0164] High surface tension hinders the fluid from overcoming the solid-liquid interface barrier and prevents it from quickly entering the capillary pores inside the canvas, significantly increasing the wetting and settling time.

[0165] The examples employ a complex system of alkyl glycosides and ethylene oxide-propylene oxide block polyethers. The block polyether molecules and alkyl glycosides self-assemble in the aqueous phase to form mixed micelles.

[0166] The polyether structure contains numerous flexible molecular segments rich in ether bonds. These segments extend into the aqueous phase from the periphery of the mixed micelles and the gas-liquid interface layer, constructing a thick spatial hydration layer. This hydration layer creates a physical steric hindrance effect, effectively shielding the internal core hydrophilic groups from the electrostatic compression and water-removing effects of high-concentration electrolytes, and resisting the salting-out effect of high-salt environments.

[0167] Transmittance data confirms that no phase separation reaction occurred in the compound system. The surfactant molecules, stable in their dissolved state, can continuously occupy and alter interfacial properties, maintaining low surface tension.

[0168] When a fluid comes into contact with a combustible surface, its low surface tension drives the liquid to wet and penetrate the porous fiber network in a very short time, resulting in a deeper level of penetration and cooling capability in fire extinguishing applications.

[0169] Test Example 4:

[0170] Take 1000g of each of the finished fluids prepared in Examples 1-3 and Comparative Examples 1-3, place them in a constant temperature water bath at 20℃ and let them stand for 24 hours to ensure that the bubbles in the system completely escape and the temperature reaches thermodynamic equilibrium.

[0171] The apparent viscosity of each group of samples was determined using an NDJ rotational viscometer. A No. 4 rotor was selected, and the rotational speed was set to 60 rpm. During the test, a constant temperature water bath was maintained for circulation. Data was recorded when the instrument reading fluctuated within ±1% of the nominal value. For each group of samples, three independent measurements were taken at three different locations, and the arithmetic mean was calculated.

[0172] Accurately weigh 100g of the finished fluid and place it in a PTFE centrifuge tube. Place the tube in a benchtop high-speed centrifuge and centrifuge at 5000 rpm for 30 minutes. Remove the centrifuge tube and discard the supernatant. Use deionized water to perform two resuscitation washes and a second centrifugation on the solid residue at the bottom. Transfer the washed residue to a 50℃ vacuum drying oven and dry it to constant weight. Weigh and calculate the percentage of solid precipitate relative to the initial mass of the finished product.

[0173] The surface tension of the samples was determined using the platinum ring method. Under constant temperature conditions of 20℃, 30 mL of the liquid to be tested was injected into the sample dish of the surface tension meter. The lifting platform was controlled to descend at a constant rate, and the maximum tensile force value at the moment of liquid film rupture was recorded. Each group of samples was tested five times, and the maximum and minimum values ​​were discarded before the average result was taken.

[0174] Table 4. Basic Physicochemical Performance Test Data of the Finished Products from Examples and Comparative Examples

[0175] Group Apparent viscosity ( ) Centrifugation solids precipitation rate (%) Surface tension (mN / m) Example 1 841.3 0.04 26.5 Example 2 856.8 0.07 25.4 Example 3 828.5 0.05 27.0 Comparative Example 1 312.6 1.83 26.8 Comparative Example 2 805.2 2.36 28.1 Comparative Example 3 864.1 0.12 40.7

[0176] Based on the data in Table 4 and Figure 4 The apparent viscosity of the finished products in Examples 1-3 remained between 828.5 and 856.8. The centrifugal solids precipitation rate is less than 0.08%, and the surface tension is controlled between 25.4 and 27.0 mN / m. The fluid also exhibits good thickening rheological properties, physical anti-precipitation stability, and interfacial activity.

[0177] The apparent viscosity of Comparative Example 1 was only 312.6. The centrifugation solids precipitation rate increased to 1.83%. This group did not undergo pH adjustment. Hydroxyethyl cellulose directly underwent surface hydration in natural high-salinity seawater and formed a dense gel shell, preventing the release of internal dry powder.

[0178] Undissolved cellulose particles settle in large quantities under centrifugal force, resulting in insufficient effective polymer concentration in the liquid phase, making it impossible to construct a complete three-dimensional cross-linked network, and the fluid loses its expected thickening effect.

[0179] The centrifugation solids precipitation rate of Comparative Example 2 reached 2.36%, which was significantly higher than that of other groups. The tetrasodium glutamate diacetic acid was removed from the formula, and the system lost its ability to chelate and control seawater hardness ions.

[0180] During the alkaline stage of the preparation process, free calcium and magnesium ions combine with hydroxide ions to generate a large number of inorganic precipitate microcrystals.

[0181] These microcrystalline particles exist as a suspended solid phase in the finished product. Under more stringent high-speed centrifugation test conditions, their aggregation and sedimentation process is accelerated and a large amount is separated and precipitated, indicating that the product has an extremely high risk of stratification and pipeline blockage during long-term storage or pumping.

[0182] The surface tension of Comparative Example 3 was as high as 40.7 mN / m. The single alkyl glycoside surfactant could not resist the compression effect of the high concentration of electrolytes in seawater, and the hydration layer of its polar head groups was destroyed. The surfactant molecules desorbed from the gas-liquid interface and precipitated into the bulk phase via reverse micelle formation, resulting in a decrease in the monolayer density at the gas-liquid interface. The fluid could not achieve a low surface tension state, and the high surface tension limited the spreading area and capillary penetration depth of the extinguishing agent on the surface of solid combustibles.

[0183] The test results cross-validated the synergistic properties of the technical solution of this invention. The conformational regulation of polymers, the threshold scale inhibition of inorganic ions, and the steric hindrance protection of surfactants work together in the seawater matrix. The absence of any single link will lead to the deterioration of key physicochemical indicators of the fluid. The embodiments fully retain the above mechanisms and achieve a balance and compliance of various performances.

[0184] Test Example 5:

[0185] Construct a standard Class A woodpile fire model. Use white pine strips with a moisture content of less than 12%, with a cross-sectional size of 30mm × 30mm and a length of 400mm. Arrange the strips in parallel with 6 strips per layer, and stack them vertically in a crisscross pattern to form 10 layers of woodpile. Place a square steel ignition plate with a side length of 300mm in the center at the bottom of the woodpile, and add n-heptane and water to the ignition plate.

[0186] A hole was drilled at the geometric center of the timber stack and a K-type armored thermocouple was inserted. The cold end of the thermocouple was connected to a multi-channel data acquisition instrument, and the sampling frequency was set to 1Hz to record the internal core temperature data of the entire combustion and extinguishing process.

[0187] Ignite the n-heptane in the ignition pan to set the fire on the woodpile. After 3 minutes of pre-ignition, remove the ignition pan from the bottom. At this point, the woodpile enters a stable deep combustion stage, with a core temperature exceeding 600°C.

[0188] The finished fluids obtained in Examples 1-3 and Comparative Examples 1-3 were respectively filled into 3L portable pressurized fire extinguishing devices of the same specifications, and the filling pressure was uniformly set to 1.2MPa.

[0189] The operator stands 2 meters away from the woodpile, turns on the fire extinguishing device and sprays it continuously onto the woodpile. The time from when the valve is opened and the fire is sprayed until the open flames on the woodpile are completely extinguished is recorded as the fire extinguishing time.

[0190] Extract the data collected by the thermocouples and calculate the average temperature change rate from the start of the spray until the core temperature of the woodpile drops to 100°C, which is called the core cooling rate.

[0191] After extinguishing the open flame and stopping the spraying, let the log stack stand naturally for 10 minutes. Then, use a standard flame torch to burn the surface of the log stack for 60 seconds. Remove the torch and observe the time it takes for the log stack to reappear with a continuous open flame. If no open flame appears after 15 minutes, record it as >15.0.

[0192] Table 5. Fire extinguishing and reignition resistance test data of the embodiments and comparative examples.

[0193] Group Time to extinguish open flames (s) Core cooling rate (°C / s) Reignition resistance time (min) Example 1 32.4 12.6 >15.0 Example 2 29.8 13.1 >15.0 Example 3 34.1 11.8 >15.0 Comparative Example 1 58.7 4.2 3.2 Comparative Example 2 71.5 3.5 4.1 Comparative Example 3 84.3 2.8 1.8

[0194] Based on the data in Table 5 and Figure 5 The flame extinguishing time of Examples 1-3 ranged from 29.8 to 34.1 seconds, the core cooling rate reached 11.8 to 13.1℃ / s, and the anti-reignition time all exceeded 15 minutes.

[0195] The flame extinguishing time for Comparative Examples 1, 2, and 3 was extended to 58.7 seconds, 71.5 seconds, and 84.3 seconds, respectively, with the core cooling rate all below 4.5℃ / s and the anti-reignition time shortened to the range of 1.8 to 4.1 minutes.

[0196] In the embodiments, the fluid simultaneously possesses suitable rheological viscosity and extremely low surface tension.

[0197] After being sprayed onto the surface of a high-temperature wood stack, the fluid forms a stable hydrogel adhesion layer on the wood surface through a thickening network, which isolates oxygen and prevents moisture from evaporating rapidly.

[0198] At the same time, the compounded surfactant reduces the solid-liquid contact angle of the liquid, allowing moisture to overcome capillary resistance and penetrate into the internal pores of the wood, directly acting on the deep smoldering area, absorbing and carrying away a large amount of heat.

[0199] The combined effect of internal and external forces extinguishes the open flame rapidly, causes the core temperature to drop sharply, and effectively prevents secondary reignition from external ignition sources.

[0200] In Comparative Example 1, a uniform polymer cross-linked network was not formed, resulting in insufficient fluid viscosity. Upon contact with the log surface, the liquid rapidly flowed away due to gravity, failing to establish an effective thickness of heat-insulating and oxygen-barrier coating on the burnt material surface.

[0201] The surface moisture is rapidly evaporated by the high temperature, which increases the time required to extinguish the fire, and the residual heat causes the wood to reignite.

[0202] Comparative Example 2 contained a large amount of inorganic precipitates and suspended matter. Solid particles caused microscopic blockage at the nozzle of the fire extinguishing device, disrupting the jet flow pattern and resulting in uneven distribution of the extinguishing agent on the surface of the timber stack.

[0203] Inorganic microcrystals cannot participate in the gelation process, which weakens the bond strength between the hydrogel layer and the surface of carbonized wood, reducing the overall fire extinguishing efficiency.

[0204] In Comparative Example 3, surfactant salting-out occurred, resulting in an abnormally high fluid surface tension. Upon contact with the woodpile, the fluid was unable to overcome the penetration barrier of the wood pores, and the agent remained entirely on the outer surface of the wood, while the deeper layers remained in a smoldering state. Thermocouple readings showed extremely slow cooling.

[0205] After the external flames were briefly suppressed, the heat accumulated inside the woodpile was conducted outwards, and the moisture evaporated completely, causing the wood to reignite violently in a very short time.

[0206] The differences in the data from each group confirm that the defects in the basic physicochemical indicators ultimately lead to the deterioration of the macroscopic fire extinguishing performance.

[0207] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A marine fire extinguishing agent that can be prepared with seawater, characterized in that, The marine fire extinguishing agent is made from the following raw materials by weight percentage: Seawater 75%–80%; Environmentally friendly nonionic surfactants: 9%–13%; Sodium lignosulfonate 6%–10%; Tetrasodium glutamate diacetic acid 0.5%–2%; Hydroxyethyl cellulose 0.5%–2%; pH adjuster 0.2%–1%; The tetrasodium glutamate diacetic acid is used to complex free hardness ions in seawater; The environmentally friendly nonionic surfactant, sodium lignosulfonate, and hydroxyethyl cellulose work synergistically to construct a spatial hydration layer and a three-dimensional network in the seawater matrix to provide physical isolation and dispersion.

2. The marine fire extinguishing agent that can be prepared with seawater according to claim 1, characterized in that, The marine fire extinguishing agent is made from the following raw materials by weight percentage: Seawater 78.5%, environmentally friendly nonionic surfactant 11%, sodium lignosulfonate 8%, tetrasodium glutamate diacetic acid 1%, hydroxyethyl cellulose 1%, and pH adjuster 0.5%.

3. A marine fire extinguishing agent that can be prepared with seawater according to claim 1, characterized in that, The environmentally friendly nonionic surfactant is composed of alkyl glycosides and ethylene oxide-propylene oxide block polyethers, with a mass ratio of 1:2 to 2:

1.

4. A marine fire extinguishing agent that can be prepared with seawater according to claim 3, characterized in that, The environmentally friendly nonionic surfactant is prepared by the following steps: The alkyl glycoside is added to a premixing vessel and heated. When the temperature reaches 45°C, the ethylene oxide-propylene oxide block polyether is added. The mixture is stirred at a constant temperature of 45°C until it is completely miscible and forms a uniform and transparent liquid phase. The mixture is then cooled to room temperature to obtain the final product.

5. A marine fire extinguishing agent that can be prepared with seawater according to claim 1, characterized in that, The seawater is either natural seawater or artificial seawater; The pH adjuster is composed of an aqueous solution of sodium hydroxide and an aqueous solution of citric acid.

6. A method for preparing a marine fire extinguishing agent that can be prepared using seawater, according to any one of claims 1-5, characterized in that, S1: According to the component ratio of the marine fire extinguishing agent, weigh seawater, environmentally friendly nonionic surfactant, sodium lignosulfonate, tetrasodium glutamate diacetic acid, hydroxyethyl cellulose and pH adjuster respectively, wherein the pH adjuster is composed of alkaline adjuster and acidic adjuster. S2: Pour the weighed seawater into the main reactor equipped with a heating jacket and mechanical stirring, and turn on the heating to raise the water temperature; S3: While stirring, add the weighed tetrasodium glutamate diacetic acid and sodium lignosulfonate in sequence, and stir at a constant temperature so that the tetrasodium glutamate diacetic acid complexes the free hardness ions. S4: Under continuous stirring, the alkaline regulator is slowly added dropwise to raise the pH of the system to an alkaline environment to induce the molecular chains to unfold. Then, the weighed environmentally friendly nonionic surfactant is added and stirred at a constant temperature. S5: While maintaining the stirring state, add the weighed hydroxyethyl cellulose into the main reactor and stir at a constant temperature until the powder is completely swollen and forms a three-dimensional network; S6: Turn off the heating and cool down, slowly add the acidic regulator to bring the pH of the system back to neutral, continue stirring and filter to obtain the finished marine fire extinguishing agent; The total mass of the alkaline regulator consumed in S4 and the acidic regulator consumed in S6 is equal to the total mass of the pH regulator weighed in S1.

7. A method for preparing a marine fire extinguishing agent that can be prepared using seawater, as described in claim 6, characterized in that, In step S2, turn on the heater to raise the water temperature to 45-50℃; In step S3, the stirring speed is 200 rpm and the constant temperature stirring time is 15 minutes.

8. A method for preparing a marine fire extinguishing agent that can be prepared using seawater, as described in claim 6, characterized in that, In step S4, the alkaline regulator is a 25wt% sodium hydroxide aqueous solution. The sodium hydroxide aqueous solution is added dropwise to raise the pH value of the system to 9.8-10.5, and the system is stirred at a constant temperature of 45-50°C for 20 minutes.

9. A method for preparing a marine fire extinguishing agent that can be prepared using seawater, as described in claim 6, characterized in that, In step S5, the hydroxyethyl cellulose is added slowly and evenly, and the mixture is stirred at a constant temperature for 30 minutes until there are no lumps.

10. A method for preparing a marine fire extinguishing agent that can be prepared using seawater, as described in claim 6, characterized in that, In step S6, the heating is turned off and the temperature is allowed to drop naturally to 25°C. The acidity regulator is a 40wt% citric acid aqueous solution. The citric acid aqueous solution is added dropwise to adjust the pH value of the system back to 6.5-7.5, and stirring is continued for 20 minutes.

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