A method for preparing a high-temperature resistant reverse osmosis membrane

Abstract

This application relates to the field of membrane separation material preparation technology, specifically to a method for preparing a high-temperature resistant reverse osmosis membrane, comprising the following steps: preparation of casting solution: the casting solution includes 8-14 parts by weight of solid polysulfone, 5-10 parts by weight of bismaleimide resin, 1-3 parts by weight of fumed silica, 75-82 parts by weight of N,N-dimethylformamide, and 0.5-3 parts by weight of pore-forming agent. The above raw materials are mixed and allowed to stand, then degassed and filtered to obtain the casting solution; the casting solution is uniformly coated onto a substrate membrane and allowed to stand, then the membrane is placed in an aqueous coagulation solution to obtain a porous supported composite base membrane; an aqueous phase solution is coated onto the porous supported composite base membrane, and it is dried; subsequently, an acyl chloride oil phase solution is coated, and post-treatment is performed to obtain the reverse osmosis composite membrane. The reverse osmosis composite membrane of this application improves the heat resistance and stability of the membrane without significant decrease in membrane flux and desalination rate, reduces the operating cost of high-temperature water treatment, and to a certain extent increases the service life of the membrane.

Description

Technical Field

[0001] This application relates to the field of membrane separation material preparation technology, specifically to a method for preparing a high-temperature resistant reverse osmosis membrane. Background Technology

[0002] Membrane separation technology, as one of the preferred technologies in water pollution control engineering, can be classified into microfiltration membranes, ultrafiltration membranes, nanofiltration membranes, and reverse osmosis membranes based on their filtration precision. Reverse osmosis membrane technology has numerous advantages in desalination and saline water treatment, including low energy consumption, low investment cost, high recovery rate, small footprint, high salt removal rate, and stable water quality. Furthermore, reverse osmosis membrane systems have a long service life, and therefore are widely used in drinking water purification, wastewater treatment, and reuse.

[0003] However, the increasing application of reverse osmosis membranes in various fields has placed higher demands on their performance, especially in the food, pharmaceutical, and textile industries, where raw water is often high-temperature wastewater, typically exceeding 45°C. Current reverse osmosis membranes on the market are generally composed of non-woven fabric, a porous support layer, and a separation layer, which suffers from drawbacks such as low strength, easy deformation, and susceptibility to breakage and peeling. Furthermore, existing reverse osmosis membranes generally operate below 40°C, thus failing to function effectively under high-temperature conditions. At high temperatures, the desalination performance of existing membranes rapidly declines, resulting in reduced membrane flux and desalination rate, thereby affecting the quality of the produced water, increasing operating costs, and shortening the membrane's lifespan.

[0004] Currently, the common practice in industry for treating high-temperature wastewater is to introduce it into a wastewater transfer tank for cooling, and then use a reverse osmosis membrane system for water purification. This method increases the number of treatment steps, leads to wastewater accumulation, and is detrimental to industrial production.

[0005] Therefore, developing high-temperature resistant reverse osmosis membranes will greatly enhance their application potential in drinking water purification and wastewater treatment. Improving the high-temperature resistance and stability of membranes without significantly reducing membrane flux and desalination rate is the main challenge facing membrane separation technology in drinking water purification and wastewater treatment. Summary of the Invention

[0006] To address the stability and performance issues of existing reverse osmosis membranes when treating high-temperature raw water, this application provides a method for preparing a high-temperature resistant reverse osmosis membrane, comprising the following steps:

[0007] S1: Preparation of casting solution: The casting solution includes 8-14 parts by weight of solid polysulfone, 5-10 parts by weight of bismaleimide resin, 1-3 parts by weight of fumed silica, 75-82 parts by weight of N,N-dimethylformamide and 0.5-3 parts by weight of pore-forming agent. Mix the above raw materials, let stand, degas and filter to obtain the casting solution.

[0008] S2: The casting solution is uniformly coated onto the polyester nonwoven fabric, and the film obtained after standing is placed in the water coagulation solution to obtain a porous supported composite base film.

[0009] S3: The porous support composite substrate membrane is coated with an aqueous solution containing amine compounds and then dried.

[0010] S4: The membrane obtained in step S3 is brought into contact with an oil phase solution containing acyl chloride compounds by coating to form a functional layer; the membrane is then dried to obtain a reverse osmosis composite membrane.

[0011] The above technical solution compensates for the deficiencies of polysulfone polymer chains, such as lack of active groups and insufficient branching or crosslinking, by introducing a bismaleimide resin containing benzene rings, imide heterocycles, and high crosslinking density into the porous support composite membrane layer. Furthermore, the bismaleimide resin, through its twisted, non-coplanar structure, effectively disperses nanomaterials between the polysulfone molecular chains, thereby enhancing the membrane's stability and mechanical properties. Simultaneously, the strong electron-withdrawing effect of the carbonyl groups in bismaleimide facilitates addition reactions with substances containing active hydrogen, such as amides, leading to better crosslinking between the support layer and the functional layer, significantly improving the thermal stability of the reverse osmosis composite membrane.

[0012] Simultaneously, by compounding with an appropriate proportion of fumed silica, the toughness and aging resistance of the prepared reverse osmosis composite membrane can be significantly improved. The inventors discovered that, due to the nanoparticle characteristics and three-dimensional chain-like microstructure of fumed silica itself, as well as its abundant surface hydroxyl groups, it can be stably cross-linked with the inherent electron-withdrawing groups of bismaleimide resin to form a stable spatial network structure. This significantly improves the overall toughness and high-temperature resistance of the reverse osmosis membrane material. Furthermore, in practical applications, the water flux of the membrane also increases significantly. Analysis suggests that this is likely due to the high porosity of fumed silica itself, which greatly increases the water flux. Additionally, the lightweight and high strength of fumed silica helps protect the structure of the reverse osmosis membrane during high-temperature operation. Without a significant decrease in membrane flux and desalination rate, the heat resistance and stability of the reverse osmosis composite membrane are greatly improved, reducing the operating cost of high-temperature water treatment and increasing the membrane's service life to some extent.

[0013] In one specific implementation, the average particle size of the fumed silica is 6-8 nm.

[0014] By adopting the above technical solution, the uniform microporous fumed silica can better crosslink with organic matter to form a stable spatial network structure, and also increase the contact area with the porous support composite membrane, so that the membrane stress is concentrated and has better heat resistance stability.

[0015] By adopting the above technical solution, the mass ratio of the bismaleimide resin to fumed silica is (2-5):1.

[0016] By adopting the above technical solution, through the organic compounding of bismaleimide resin and fumed silica, the fumed silica is properly dispersed in the gaps between polymer molecular chains, connecting the polymer molecular chains together, thereby making the stress of the porous support composite membrane more concentrated. When the reverse osmosis composite membrane is running at high temperature, it plays a role in strengthening and toughening to maintain the stable cross-linking of the membrane, thereby enhancing the heat resistance stability of the membrane.

[0017] In one specific embodiment, the aqueous solution comprises the following components in parts by weight: 4-12 parts diamine, 0.5-3 parts silver nanoparticles, 2-2.5 parts pH adjuster, 0.15-0.45 parts surfactant, 0.15-1.2 parts acid acceptor, 2-4 parts modifier, 1-2.5 parts N,N-dimethylacetamide, and 72-78 parts purified water. The casting solution also includes 1-3 parts mercaptosilane coupling agent. Preferably, the average particle size of the silver nanoparticles is not greater than 10 nm.

[0018] By employing the above technical solution, diamine, as an amine monomer, undergoes cross-linking polymerization with acyl chloride. A pH adjuster is used to regulate the acidity or alkalinity of the liquid, promoting the smooth progress of the interfacial reaction in the functional layer. Silver nanoparticles can be embedded in the functional layer undergoing the interfacial polymerization reaction through interaction with a mercaptosilane coupling agent, increasing the water flux of the reverse osmosis membrane while preventing the loss of nano-silver in water. The uniform particle size of the silver nanoparticles effectively improves the uniformity and stability of the reverse osmosis composite membrane, and the nano-silver can also promote the bactericidal or bacteriostatic properties of the composite membrane. The mercaptosilane coupling agent better bonds the porous support layer and effectively cross-links the silver nanoparticles in the functional layer, promoting efficient interfacial fusion. Surfactants have good tensile strength, which can optimize the performance of the composite membrane. An acid acceptor can neutralize the generated acidic substances to prevent them from combining with chloride ions in the water and affecting the interfacial polymerization reaction. A modifier hydrolyzes and modifies the surface of the support layer, increasing the active groups on the surface. N,N-dimethylacetamide, as a polar solvent, has good solubility and catalyzes the formation of the composite membrane.

[0019] In one specific feasible embodiment, the diamine is one or more of m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, 4-chloro-1,3-phenylenediamine, and dimethylphenylenediamine; the pH adjuster is one or more of camphor sulfonic acid, tannic acid, and citric acid; the surfactant is one or more of sodium dodecyl sulfonate, sodium dodecylbenzene sulfonate, sodium lauryl sulfonate, and sodium glycocholate; the acid acceptor is sodium hydroxide; and the modifier is N-methylpyrrolidone.

[0020] By adopting the above technical solution and selecting specific phenyl diamines, the desalination rate of the composite membrane can be improved, ensuring that the desalination rate of the reverse osmosis composite membrane remains within a high range during high-temperature operation. Analysis suggests that the large number of phenyl groups in the functional layer forms a conjugated system, making the system more stable and reducing internal energy, thus enhancing the heat resistance of the functional layer membrane. pH adjusters, surfactants, and acid acceptors can further optimize the overall structural performance of the reverse osmosis composite membrane. pH adjusters and acid acceptors facilitate the smooth progress of the interfacial polymerization reaction in the functional layer. Surfactants have good tensile strength and can optimize the overall crosslinking and heat resistance stability of the composite membrane.

[0021] In one specific implementation, the acyl chloride oil phase solution comprises 1-4 parts by weight of acyl chloride monomer and 80-88 parts by weight of oil phase solvent, wherein the acyl chloride monomer is one or more of pyromellitic terephthaloyl chloride, 4,4'-biphenyldicarboxylic acid chloride, benzene disulfonyl chloride, and terephthaloyl chloride, and the oil phase solvent is one or more of n-hexane, cyclohexane, or heptane.

[0022] By adopting the above technical solution, acyl chloride monomers are soluble in organic solvents, and acyl chloride monomers in oil-phase polar solvents have better solubility, which is conducive to the interfacial polymerization with aqueous solutions to form polyamide functional layers.

[0023] In one specific implementation, the mercaptosilane coupling agent is γ-mercaptopropyltrimethoxysilane or γ-mercaptopropyltriethoxysilane.

[0024] By adopting the above technical solution, the mercaptosilane coupling agent selected is γ-mercaptopropyltrimethoxysilane or γ-mercaptopropyltriethoxysilane, which can interact with silver nanoparticles in aqueous solution and be embedded in the separation layer where interfacial polymerization occurs to form a stable functional surface layer.

[0025] In one specific implementation, the porogen is selected from one or more of polyethylene glycol, polyvinylpyrrolidone, and 1,4-dioxane.

[0026] By adopting the above technical solutions, the resistance during water mass transfer can be reduced, which is beneficial to increasing the water flux of the reverse osmosis membrane.

[0027] In one specific implementation, the temperature range of the water-based coagulation solution is 8-16°C.

[0028] By adopting the above technical solution, it is beneficial for the casting solution to undergo phase transformation in water into a porous support base membrane that meets the requirements.

[0029] In one specific feasible implementation, after step S4, the obtained reverse osmosis membrane is first washed with pure water, wetted with glycerin, then coated with PVA on the surface of the composite membrane, and dried at 60-80°C.

[0030] By adopting the above technical solution, a non-fouling layer is formed on the surface of the polyamide layer by cross-linking and adhering polyvinyl alcohol on the surface of the functional layer. At the same time, the hydrophilicity and chlorine resistance of the reverse osmosis membrane composite membrane can be improved, thus extending the service life of the reverse osmosis membrane composite membrane.

[0031] In summary, this application includes at least one of the following beneficial technical effects:

[0032] 1. By introducing a bismaleimide resin containing benzene rings, imide heterocycles, and a high crosslinking density into the porous support composite membrane layer, the defects of insufficient active groups and branches or inadequate crosslinking in the polysulfone polymer chain are compensated. Furthermore, the bismaleimide resin, through its twisted, non-coplanar structure, effectively disperses nanomaterials between the polysulfone molecular chains, thereby enhancing the membrane's stability and mechanical properties. Simultaneously, the strong electron-withdrawing effect of the carbonyl group in bismaleimide facilitates addition reactions with substances containing active hydrogen, such as amides, leading to better crosslinking between the support layer and the functional layer, significantly improving the thermal stability of the reverse osmosis composite membrane.

[0033] 2. Through the organic compounding of bismaleimide resin and fumed silica, fumed silica is properly dispersed in the gaps between polymer molecular chains. The three-dimensional chain structure of fumed silica and the large number of free hydroxyl groups distributed on its surface can be fully embedded in the bismaleimide resin and the abundant strong electron-withdrawing groups of the molecular chains, connecting the polymer molecular chains together. This makes the stress of the porous support composite membrane more concentrated. When the reverse osmosis composite membrane is subjected to external impact, it plays a role in strengthening and toughening, and enhancing the stability of the membrane.

[0034] 3. Silver nanoparticles can be embedded in the functional layer that undergoes interfacial polymerization through interaction with mercaptosilane coupling agents. This increases the water flux of the reverse osmosis membrane while preventing the loss of silver nanoparticles in the water. It forms a stable functional layer and crosslinks with the porous support layer, enhancing the stability of the composite membrane, while the water flux and rejection rate of the membrane do not decrease significantly. Detailed Implementation

[0035] Some of the raw materials used in the preparation examples and embodiments:

[0036] Bismaleimide resin CAS No.: 13676-54-5, model: pe331; γ-mercaptopropyltrimethoxysilane CAS No.: 4420-74-0, model: KH-591; γ-mercaptopropyltriethoxysilane CAS No.: 14814-09-6, model: KH-592; Fumed silica model: A380; The base film is polyester nonwoven fabric.

[0037] Unless otherwise specified, all raw materials used in the examples and comparative examples are commercially available products.

[0038] Example

[0039] Example 1

[0040] A method for preparing a high-temperature resistant reverse osmosis membrane includes the following steps:

[0041] S1: Dissolve 8g of solid polysulfone, 5g of bismaleimide resin, and 1g of fumed silica with an average particle size of 6-8nm in 75g of N,N-dimethylformamide, then add 0.5g of 1,4-dioxane and mix well. Let stand for 10s, degas and filter to obtain casting solution; S2: Extrude the casting solution evenly onto polyester nonwoven fabric, let stand for 10s to obtain film, and then place it in 8℃ water coagulation solution to obtain porous supported composite base film;

[0042] S3: Dissolve 4-chloro-1,3-phenylenediamine in 72g of water, then add 1g of N,N-dimethylacetamide, 0.15g of sodium hydroxide, 0.15g of sodium dodecyl sulfonate, 2g of camphor sulfonic acid and 2g of N-methylpyrrolidone in sequence to obtain an aqueous solution. Coat the aqueous solution containing amine compounds uniformly onto the porous support composite substrate obtained in step S2 by contact coating, and place it in a vacuum oven at 60℃ for 3min to remove surface moisture.

[0043] S4: Take 1g of benzene disulfonyl chloride and 80g of n-hexane, mix them to obtain an oil phase solution, and uniformly coat the oil phase solution containing acyl chloride compounds onto the membrane obtained in step S3 by contact coating. After completion, dry at 60℃ for 5min to obtain a reverse osmosis composite membrane.

[0044] Example 2

[0045] A method for preparing a high-temperature resistant reverse osmosis membrane includes the following steps:

[0046] S1: Take 10g solid polysulfone, 6g bismaleimide resin, 2g fumed silica with an average particle size of 6-8nm, dissolve in 82g N,N-dimethylformamide, add 3g polyvinylpyrrolidone, mix evenly, let stand for 10s, degas and filter to obtain casting solution.

[0047] S2: The casting solution is uniformly extruded and coated onto the polyester nonwoven fabric, and after standing for 10 seconds, a film is obtained. Then, it is placed in a 10°C water coagulation solution to obtain a porous support composite base film.

[0048] S3: Dissolve 6g of o-phenylenediamine in 78g of water, then add 2g of N,N-dimethylacetamide, 1.2g of sodium hydroxide, 0.15g of sodium dodecylbenzenesulfonate, 2g of tannic acid and 3g of N-methylpyrrolidone in sequence to obtain an aqueous solution. Coat the aqueous solution containing amine compounds uniformly onto the porous support composite substrate obtained in step S2 by contact coating, and place it in a vacuum oven at 60℃ for 3min to remove surface moisture.

[0049] S4: Take 2g of 4,4'-biphenyldicarboxylic acid chloride and 84g of cyclohexane, mix them to obtain an oil phase solution, and uniformly coat the oil phase solution containing acyl chloride compounds onto the membrane obtained in step S3 by contact coating. After completion, dry at 60℃ for 5min to obtain a reverse osmosis composite membrane.

[0050] Example 3

[0051] A method for preparing a high-temperature resistant reverse osmosis membrane includes the following steps:

[0052] S1: Take 12g of solid polysulfone, 10g of bismaleimide resin, 2g of fumed silica with an average particle size of 6-8nm, dissolve them in 80g of N,N-dimethylformamide, then add 2g of polyethylene glycol and mix evenly. Let stand for 10s, degas and filter to obtain casting solution; S2: Extrude the casting solution evenly onto polyester nonwoven fabric, let stand for 10s to obtain film, then place it in 8℃ water coagulation solution to obtain porous support composite base film;

[0053] S3: Dissolve 10g of m-phenylenediamine in 76g of water, then add 2.5g of N,N-dimethylacetamide, 1.2g of sodium hydroxide, 0.35g of sodium lauryl sulfonate, 0.35g of citric acid and 3g of N-methylpyrrolidone in sequence to obtain an aqueous solution. Coat the aqueous solution containing amine compounds uniformly onto the porous support composite substrate obtained in step S2 by contact coating, and place it in a vacuum oven at 60℃ for 3min to remove surface moisture.

[0054] S4: Take 3g of benzene disulfonyl chloride and 86g of cyclohexane, mix them to obtain an oil phase solution, and uniformly coat the oil phase solution containing acyl chloride compounds onto the membrane obtained in step S3 by contact coating. After completion, dry at 60℃ for 5min to obtain a reverse osmosis composite membrane.

[0055] Example 4

[0056] A method for preparing a high-temperature resistant reverse osmosis membrane includes the following steps:

[0057] S1: Take 14g of solid polysulfone, 6g of bismaleimide resin, 3g of fumed silica with an average particle size of 6-8nm, place them in 80g of N,N-dimethylformamide, add 2g of polyvinylpyrrolidone, mix well, let stand for 10s to degas and filter to obtain casting solution.

[0058] S2: The casting solution is uniformly extruded and coated onto the polyester nonwoven fabric, and after standing for 10 seconds, a film is obtained. Then, it is placed in a 16℃ water coagulation solution to obtain a porous support composite base film.

[0059] S3: Dissolve 12g of m-phenylenediamine in 78g of water, then add 2.5g of N,N-dimethylacetamide, 1.2g of sodium hydroxide, 0.45g of sodium cholate, 0.45g of citric acid and 4g of N-methylpyrrolidone in sequence to obtain an aqueous solution. Coat the aqueous solution containing amine compounds uniformly onto the porous support composite substrate obtained in step S2 by contact coating, and place it in a vacuum oven at 60℃ for 3min to remove surface moisture.

[0060] S4: Take 4g of terephthaloyl chloride and 88g of heptane, mix them to obtain an oil phase solution, and uniformly coat the oil phase solution containing acyl chloride compounds onto the membrane obtained in step S3 by contact coating. After completion, dry at 60℃ for 5min to obtain a reverse osmosis composite membrane.

[0061] Example 5

[0062] A method for preparing a high-temperature resistant reverse osmosis membrane includes the following steps:

[0063] S1: Take 12g of solid polysulfone, 6g of bismaleimide resin, 2g of fumed silica with an average particle size of 6-8nm, place them in 80g of N,N-dimethylformamide, add 2g of polyethylene glycol and mix well. Let stand for 10s, degas and filter to obtain casting solution.

[0064] S2: The casting solution is uniformly extruded and coated onto the polyester nonwoven fabric. After standing for 10 seconds, a film is obtained. Then, it is placed in an 8°C water coagulation solution to obtain a porous support composite base film.

[0065] S3: Dissolve 10g of m-phenylenediamine in 76g of water, then add 2.5g of N,N-dimethylacetamide, 2.5g of sodium hydroxide, 2.5g of sodium lauryl sulfonate, 2.5g of citric acid and 3g of N-methylpyrrolidone in sequence to obtain an aqueous solution. Coat the aqueous solution containing amine compounds uniformly onto the porous support composite substrate obtained in step S2 by contact coating, and place it in a vacuum oven at 60℃ for 3min to remove surface moisture.

[0066] S4: Take 3g of benzene disulfonyl chloride and 86g of cyclohexane, mix them to obtain an oil phase solution, and uniformly coat the oil phase solution containing acyl chloride compounds onto the membrane obtained in step S3 by contact coating. After completion, dry at 60℃ for 5min to obtain a reverse osmosis composite membrane.

[0067] Example 6

[0068] A method for preparing a high-temperature resistant reverse osmosis membrane includes the following steps:

[0069] S1: Take 12g of solid polysulfone, 10g of bismaleimide resin, 2g of fumed silica with an average particle size of 6-8nm, place them in 80g of N,N-dimethylformamide, then add 2g of polyethylene glycol and 3g of γ-mercaptopropyltrimethoxysilane, mix well, let stand for 10s, degas and filter to obtain casting solution.

[0070] S2: The casting solution is uniformly extruded and coated onto the polyester nonwoven fabric. After standing for 10 seconds, a film is obtained. Then, it is placed in an 8°C water coagulation solution to obtain a porous support composite base film.

[0071] S3: Dissolve 10g of m-phenylenediamine in 76g of water, then add 2.5g of N,N-dimethylacetamide, 2.5g of sodium hydroxide, 0.35g of sodium lauryl sulfonate, 2.5g of citric acid, 2.5g of silver nanoparticles and 3g of N-methylpyrrolidone in sequence to obtain an aqueous solution. Coat the aqueous solution containing amine compounds uniformly onto the porous support composite substrate obtained in step S2 by contact coating, and place it in a vacuum oven at 60℃ for 3min to remove surface moisture.

[0072] S4: Take 3g of benzene disulfonyl chloride and 86g of cyclohexane, mix them to obtain an oil phase solution, and uniformly coat the oil phase solution containing acyl chloride compounds onto the membrane obtained in step S3 by contact coating. After completion, dry at 60℃ for 5min to obtain a reverse osmosis composite membrane.

[0073] Example 7

[0074] A method for preparing a high-temperature resistant reverse osmosis membrane includes the following steps:

[0075] S1: Take 12g of solid polysulfone, 10g of bismaleimide resin, and 1g of fumed silica with an average particle size of 6-8nm and place them in 80g of N,N-dimethylformamide. Then add 2g of polyethylene glycol and 3g of γ-mercaptopropyltrimethoxysilane and mix evenly. Let stand for 10s, degas and filter to obtain casting solution.

[0076] S2: The casting solution is uniformly extruded and coated onto the polyester nonwoven fabric. After standing for 10 seconds, a film is obtained. Then, it is placed in an 8°C water coagulation solution to obtain a porous support composite base film.

[0077] S3: Dissolve 10g of m-phenylenediamine in 76g of water, then add 2.5g of N,N-dimethylacetamide, 1.2g of sodium hydroxide, 0.35g of sodium lauryl sulfonate, 2.5g of citric acid, 2.5g of silver nanoparticles and 2.5g of N-methylpyrrolidone in sequence to obtain an aqueous solution. Coat the aqueous solution containing amine compounds uniformly onto the porous support composite substrate obtained in step S2 by contact coating, and place it in a vacuum oven at 60℃ for 3min to remove surface moisture.

[0078] S4: Take 3g of benzene disulfonyl chloride and 86g of cyclohexane, mix them to obtain an oil phase solution, and uniformly coat the oil phase solution containing acyl chloride compounds onto the membrane obtained in step S3 by contact coating. After completion, dry at 60℃ for 5min to obtain a reverse osmosis composite membrane.

[0079] Example 8

[0080] A method for preparing a high-temperature resistant reverse osmosis membrane includes the following steps:

[0081] S1: Take 12g of solid polysulfone, 5g of bismaleimide resin, and 3g of fumed silica with an average particle size of 6-8nm and place them in 80g of N,N-dimethylformamide. Then add 2g of polyethylene glycol and 3g of γ-mercaptopropyltrimethoxysilane and mix evenly. Let stand for 10s, degas and filter to obtain casting solution.

[0082] S2: The casting solution is uniformly extruded and coated onto the polyester nonwoven fabric. After standing for 10 seconds, a film is obtained. Then, it is placed in an 8°C water coagulation solution to obtain a porous support composite base film.

[0083] S3: Dissolve 10g of m-phenylenediamine in 76g of water, then add 2.5g of N,N-dimethylacetamide, 2.5g of sodium hydroxide, 0.35g of sodium lauryl sulfonate, 2.5g of citric acid, 2.5g of silver nanoparticles and 3g of N-methylpyrrolidone in sequence to obtain an aqueous solution. Coat the aqueous solution containing amine compounds uniformly onto the porous support composite substrate obtained in step S2 by contact coating, and place it in a vacuum oven at 60℃ for 3min to remove surface moisture.

[0084] S4: Take 3g of benzene disulfonyl chloride and 86g of cyclohexane, mix them to obtain an oil phase solution, and uniformly coat the oil phase solution containing acyl chloride compounds onto the membrane obtained in step S3 by contact coating. After completion, dry at 60℃ for 5min to obtain a reverse osmosis composite membrane.

[0085] Example 9

[0086] A method for preparing a high-temperature resistant reverse osmosis membrane includes the following steps:

[0087] S1: Take 12g of solid polysulfone, 6g of bismaleimide resin, and 3g of fumed silica with an average particle size of 6-8nm and place them in 80g of N,N-dimethylformamide. Then add 2g of polyethylene glycol and 3g of γ-mercaptopropyltrimethoxysilane and mix evenly. Let stand for 10s, degas and filter to obtain casting solution.

[0088] S2: The casting solution is uniformly extruded and coated onto the polyester nonwoven fabric. After standing for 10 seconds, a film is obtained. Then, it is placed in an 8°C water coagulation solution to obtain a porous support composite base film.

[0089] S3: Dissolve 10g of m-phenylenediamine in 76g of water, then add 2.5g of N,N-dimethylacetamide, 1.2g of sodium hydroxide, 0.35g of sodium lauryl sulfonate, 2.5g of citric acid, 2.5g of silver nanoparticles and 3g of N-methylpyrrolidone in sequence to obtain an aqueous solution. Coat the aqueous solution containing amine compounds uniformly onto the porous support composite substrate obtained in step S2 by contact coating, and place it in a vacuum oven at 60℃ for 3min to remove surface moisture.

[0090] S4: Take 3g of benzene disulfonyl chloride and 86g of cyclohexane, mix them to obtain an oil phase solution, and uniformly coat the oil phase solution containing acyl chloride compounds onto the membrane obtained in step S3 by contact coating. After completion, dry at 60℃ for 5min to obtain a reverse osmosis composite membrane.

[0091] Example 10

[0092] A method for preparing a high-temperature resistant reverse osmosis membrane includes the following steps:

[0093] S1: Take 12g of solid polysulfone, 10g of bismaleimide resin, and 2g of fumed silica with an average particle size of 6-8nm and place them in 80g of N,N-dimethylformamide. Then add 2g of polyethylene glycol and 3g of γ-mercaptopropyltrimethoxysilane and mix evenly. Let stand for 10s, degas and filter to obtain casting solution.

[0094] S2: The casting solution is uniformly extruded and coated onto the polyester nonwoven fabric. After standing for 10 seconds, a film is obtained. Then, it is placed in an 8°C water coagulation solution to obtain a porous support composite base film.

[0095] S3: Dissolve 10g of triethylenediamine in 76g of water, then add 2.5g of N,N-dimethylacetamide, 1.2g of sodium hydroxide, 0.35g of sodium lauryl sulfonate, 2.5g of citric acid, 2.5g of silver nanoparticles and 3g of N-methylpyrrolidone in sequence to obtain an aqueous solution. Coat the aqueous solution containing amine compounds uniformly onto the porous support composite substrate obtained in step S2 by contact coating, and place it in a vacuum oven at 60℃ for 3min to remove surface moisture.

[0096] S4: Take 3g of benzene disulfonyl chloride and 86g of cyclohexane, mix them to obtain an oil phase solution, and uniformly coat the oil phase solution containing acyl chloride compounds onto the membrane obtained in step S3 by contact coating. After completion, dry at 60℃ for 5min to obtain a reverse osmosis composite membrane.

[0097] Example 11

[0098] A method for preparing a high-temperature resistant reverse osmosis membrane includes the following steps:

[0099] S1: Take 12g of solid polysulfone, 10g of bismaleimide resin, and 2g of fumed silica with an average particle size of 25nm and place them in 80g of N,N-dimethylformamide. Then add 2g of polyethylene glycol and 3g of γ-mercaptopropyltrimethoxysilane and mix evenly. Let stand for 10s, degas and filter to obtain casting solution.

[0100] S2: The casting solution is uniformly extruded and coated onto the polyester nonwoven fabric. After standing for 10 seconds, a film is obtained. Then, it is placed in an 8°C water coagulation solution to obtain a porous support composite base film.

[0101] S3: Dissolve 10g of m-phenylenediamine in 76g of water, then add 2.5g of N,N-dimethylacetamide, 1.2g of sodium hydroxide, 0.35g of sodium lauryl sulfonate, 2.5g of citric acid, 2.5g of silver nanoparticles and 3g of N-methylpyrrolidone in sequence to obtain an aqueous solution. Coat the aqueous solution containing amine compounds uniformly onto the porous support composite substrate obtained in step S2 by contact coating, and place it in a vacuum oven at 60℃ for 3min to remove surface moisture.

[0102] S4: Take 3g of benzene disulfonyl chloride and 86g of cyclohexane, mix them to obtain an oil phase solution, and uniformly coat the oil phase solution containing acyl chloride compounds onto the membrane obtained in step S3 by contact coating. After completion, dry at 60℃ for 5min to obtain a reverse osmosis composite membrane.

[0103] Example 12

[0104] A method for preparing a high-temperature resistant reverse osmosis membrane includes the following steps:

[0105] S1: Take 12g of solid polysulfone, 10g of bismaleimide resin, and 2g of fumed silica with an average particle size of 6-8nm and place them in 80g of N,N-dimethylformamide. Then add 2g of polyethylene glycol and 3g of γ-mercaptopropyltrimethoxysilane and mix evenly. Let stand for 10s, degas and filter to obtain casting solution.

[0106] S2: The casting solution is uniformly extruded and coated onto the polyester nonwoven fabric. After standing for 10 seconds, a film is obtained. Then, it is placed in an 8°C water coagulation solution to obtain a porous support composite base film.

[0107] S3: Dissolve 10g of m-phenylenediamine in 76g of water, then add 2.5g of N,N-dimethylacetamide, 1.2g of sodium hydroxide, 0.35g of sodium lauryl sulfonate, 2.5g of citric acid, 2.5g of silver nanoparticles and 3g of N-methylpyrrolidone in sequence to obtain an aqueous solution. Coat the aqueous solution containing amine compounds uniformly onto the porous support composite substrate obtained in step S2 by contact coating, and place it in a vacuum oven at 60℃ for 3min to remove surface moisture.

[0108] S4: Take 3g of benzene disulfonyl chloride and 86g of cyclohexane, mix them to obtain an oil phase solution, and uniformly coat the oil phase solution containing acyl chloride compounds onto the membrane obtained in step S3 by contact coating. After completion, dry at 60℃ for 5min, then wash with pure water and wet with glycerin, and coat the surface of the composite membrane with PVA. Finally, dry at 60℃ for 6min to obtain the reverse osmosis composite membrane.

[0109] Example 13

[0110] A method for preparing a high-temperature resistant reverse osmosis membrane includes the following steps:

[0111] S1: Take 12g of solid polysulfone, 10g of bismaleimide resin, and 2g of fumed silica with an average particle size of 6-8nm and place them in 80g of N,N-dimethylformamide. Then add 2g of polyethylene glycol and 3g of γ-mercaptopropyltrimethoxysilane and mix evenly. Let stand for 10s, degas and filter to obtain casting solution.

[0112] S2: The casting solution is uniformly extruded and coated onto the polyester nonwoven fabric. After standing for 10 seconds, a film is obtained. Then, it is placed in an 8°C water coagulation solution to obtain a porous support composite base film.

[0113] S3: Dissolve 10g of m-phenylenediamine in 76g of water, then add 2.5g of N,N-dimethylacetamide, 1.2g of sodium hydroxide, 0.35g of sodium lauryl sulfonate, 2.5g of citric acid, 2.5g of silver nanoparticles and 3g of N-methylpyrrolidone in sequence to obtain an aqueous solution. Coat the aqueous solution containing amine compounds uniformly onto the porous support composite substrate obtained in step S2 by contact coating, and place it in a vacuum oven at 60℃ for 3min to remove surface moisture.

[0114] S4: Take 3g of benzene disulfonyl chloride and 86g of cyclohexane, mix them to obtain an oil phase solution, and uniformly coat the oil phase solution containing acyl chloride compounds onto the membrane obtained in step S3 by contact coating. After completion, dry at 60℃ for 5min, then wash with pure water and wet with glycerin, and coat PVA on the surface of the composite membrane. Finally, dry at 80℃ for 6min to obtain the reverse osmosis composite membrane.

[0115] Example 14

[0116] A method for preparing a high-temperature resistant reverse osmosis membrane includes the following steps:

[0117] S1: Take 12g of solid polysulfone, 10g of bismaleimide resin, and 2g of fumed silica with an average particle size of 6-8nm and place them in 80g of N,N-dimethylformamide. Then add 2g of polyethylene glycol and 1g of γ-mercaptopropyltrimethoxysilane and mix evenly. Let stand for 10s, degas and filter to obtain casting solution.

[0118] S2: The casting solution is uniformly extruded and coated onto the polyester nonwoven fabric. After standing for 10 seconds, a film is obtained. Then, it is placed in an 8°C water coagulation solution to obtain a porous support composite base film.

[0119] S3: Dissolve 10g of m-phenylenediamine in 76g of water, then add 2.5g of N,N-dimethylacetamide, 0.35g of sodium hydroxide, 0.35g of sodium lauryl sulfonate, 2.5g of citric acid and 0.35g of N-methylpyrrolidone in sequence to obtain an aqueous solution. Coat the aqueous solution containing amine compounds uniformly onto the porous support composite substrate obtained in step S2 by contact coating, and place it in a vacuum oven at 60℃ for 3min to remove surface moisture.

[0120] S4: Take 3g of benzene disulfonyl chloride and 86g of cyclohexane, mix them to obtain an oil phase solution, and uniformly coat the oil phase solution containing acyl chloride compounds onto the membrane obtained in step S3 by contact coating. After completion, dry at 60℃ for 5min to obtain a reverse osmosis composite membrane.

[0121] Example 15

[0122] A method for preparing a high-temperature resistant reverse osmosis membrane includes the following steps:

[0123] S1: Take 12g of solid polysulfone, 10g of bismaleimide resin, and 2g of fumed silica with an average particle size of 6-8nm and place them in 80g of N,N-dimethylformamide. Then add 2g of polyethylene glycol and 3g of γ-mercaptopropyltrimethoxysilane and mix evenly. Let stand for 10s, degas and filter to obtain casting solution.

[0124] S2: The casting solution is uniformly extruded and coated onto the polyester nonwoven fabric. After standing for 10 seconds, a film is obtained. Then, it is placed in an 8°C water coagulation solution to obtain a porous support composite base film.

[0125] S3: Dissolve 10g of m-phenylenediamine in 76g of water, then add 2.5g of N,N-dimethylacetamide, 0.35g of sodium hydroxide, 0.35g of sodium lauryl sulfonate, 2.5g of citric acid and 0.35g of N-methylpyrrolidone in sequence to obtain an aqueous solution. Coat the aqueous solution containing amine compounds uniformly onto the porous support composite substrate obtained in step S2 by contact coating, and place it in a vacuum oven at 60℃ for 3min to remove surface moisture.

[0126] S4: Take 3g of benzene disulfonyl chloride and 86g of cyclohexane, mix them to obtain an oil phase solution, and uniformly coat the oil phase solution containing acyl chloride compounds onto the membrane obtained in step S3 by contact coating. After completion, dry at 60℃ for 5min to obtain a reverse osmosis composite membrane.

[0127] Example 16

[0128] A method for preparing a high-temperature resistant reverse osmosis membrane includes the following steps:

[0129] S1: Take 12g of solid polysulfone, 10g of bismaleimide resin, and 2g of fumed silica with an average particle size of 6-8nm and place them in 80g of N,N-dimethylformamide. Then add 2g of polyethylene glycol and mix evenly. Let stand for 10s, degas and filter to obtain casting solution.

[0130] S2: The casting solution is uniformly extruded and coated onto the polyester nonwoven fabric. After standing for 10 seconds, a film is obtained. Then, it is placed in an 8°C water coagulation solution to obtain a porous support composite base film.

[0131] S3: Dissolve 10g of m-phenylenediamine in 76g of water, then add 2.5g of N,N-dimethylacetamide, 0.35g of sodium hydroxide, 0.35g of sodium lauryl sulfonate, 2.5g of citric acid, 3g of silver nanoparticles and 3g of N-methylpyrrolidone in sequence to obtain an aqueous solution. Coat the aqueous solution containing amine compounds uniformly onto the porous support composite substrate obtained in step S2 by contact coating, and place it in a vacuum oven at 60℃ for 3min to remove surface moisture.

[0132] S4: Take 3g of benzene disulfonyl chloride and 86g of cyclohexane, mix them to obtain an oil phase solution, and uniformly coat the oil phase solution containing acyl chloride compounds onto the membrane obtained in step S3 by contact coating. After completion, dry at 60℃ for 5min to obtain a reverse osmosis composite membrane.

[0133] Example 17

[0134] A method for preparing a high-temperature resistant reverse osmosis membrane includes the following steps:

[0135] S1: Take 12g of solid polysulfone, 10g of bismaleimide resin, and 2g of fumed silica with an average particle size of 6-8nm and place them in 80g of N,N-dimethylformamide. Then add 2g of polyethylene glycol and mix evenly. Let stand for 10s, degas and filter to obtain casting solution.

[0136] S2: The casting solution is uniformly extruded and coated onto the polyester nonwoven fabric. After standing for 10 seconds, a film is obtained. Then, it is placed in an 8°C water coagulation solution to obtain a porous support composite base film.

[0137] S3: Dissolve 10g of m-phenylenediamine in 76g of water, then add 2.5g of N,N-dimethylacetamide, 0.35g of sodium hydroxide, 0.35g of sodium lauryl sulfonate, 2.5g of citric acid, 3g of silver nanoparticles and 3g of N-methylpyrrolidone in sequence to obtain an aqueous solution. Coat the aqueous solution containing amine compounds uniformly onto the porous support composite substrate obtained in step S2 by contact coating, and place it in a vacuum oven at 60℃ for 3min to remove surface moisture.

[0138] S4: Take 3g of benzene disulfonyl chloride and 86g of cyclohexane, mix them to obtain an oil phase solution, and uniformly coat the oil phase solution containing acyl chloride compounds onto the membrane obtained in step S3 by contact coating. After completion, dry at 60℃ for 5min to obtain a reverse osmosis composite membrane.

[0139] Example 18

[0140] A method for preparing a high-temperature resistant reverse osmosis membrane includes the following steps:

[0141] S1: Take 12g of solid polysulfone, 10g of bismaleimide resin, and 2g of fumed silica with an average particle size of 6-8nm and place them in 80g of N,N-dimethylformamide. Then add 2g of polyethylene glycol and mix evenly. Let stand for 10s, degas and filter to obtain casting solution.

[0142] S2: The casting solution is uniformly extruded and coated onto the polyester nonwoven fabric. After standing for 10 seconds, a film is obtained. Then, it is placed in an 8°C water coagulation solution to obtain a porous support composite base film.

[0143] S3: Dissolve 10g of m-phenylenediamine in 76g of water, then add 2.5g of N,N-dimethylacetamide, 0.35g of sodium hydroxide, 0.35g of sodium lauryl sulfonate, 2.5g of citric acid, 3g of silver nanoparticles and 3g of N-methylpyrrolidone in sequence to obtain an aqueous solution. Coat the aqueous solution containing amine compounds uniformly onto the porous support composite substrate obtained in step S2 by contact coating, and place it in a vacuum oven at 60℃ for 3min to remove surface moisture.

[0144] S4: Take 3g of benzene disulfonyl chloride and 86g of cyclohexane, mix them to obtain an oil phase solution, and uniformly coat the oil phase solution containing acyl chloride compounds onto the membrane obtained in step S3 by contact coating. After completion, dry at 60℃ for 5min to obtain a reverse osmosis composite membrane.

[0145] Example 19

[0146] A method for preparing a high-temperature resistant reverse osmosis membrane includes the following steps:

[0147] S1: Take 12g of solid polysulfone, 10g of bismaleimide resin, and 2g of fumed silica with an average particle size of 6-8nm and place them in 80g of N,N-dimethylformamide. Then add 2g of polyethylene glycol and 1g of γ-mercaptopropyltrimethoxysilane and mix evenly. Let stand for 10s, degas and filter to obtain casting solution.

[0148] S2: The casting solution is uniformly extruded and coated onto the polyester nonwoven fabric. After standing for 10 seconds, a film is obtained. Then, it is placed in an 8°C water coagulation solution to obtain a porous support composite base film.

[0149] S3: Dissolve 10g of m-phenylenediamine in 76g of water, then add 2.5g of N,N-dimethylacetamide, 0.35g of sodium hydroxide, 0.35g of sodium lauryl sulfonate, 2.5g of citric acid, 3g of silver nanoparticles and 3g of N-methylpyrrolidone in sequence to obtain an aqueous solution. Coat the aqueous solution containing amine compounds uniformly onto the porous support composite substrate obtained in step S2 by contact coating, and place it in a vacuum oven at 60℃ for 3min to remove surface moisture.

[0150] S4: Take 3g of benzene disulfonyl chloride and 86g of cyclohexane, mix them to obtain an oil phase solution, and uniformly coat the oil phase solution containing acyl chloride compounds onto the membrane obtained in step S3 by contact coating. After completion, dry at 60℃ for 5min to obtain a reverse osmosis composite membrane.

[0151] Comparative Example

[0152] Comparative Example 1

[0153] A method for preparing a high-temperature resistant reverse osmosis membrane includes the following steps:

[0154] S1: Dissolve 12g of solid polysulfone in 80g of N,N-dimethylformamide, add 2g of polyethylene glycol and mix well. Let stand to remove bubbles and filter to obtain casting solution.

[0155] S2: The casting solution is uniformly extruded and coated onto the polyester nonwoven fabric. After standing for 10 seconds, a film is obtained. Then, it is placed in an 8°C water coagulation solution to obtain a porous support composite base film.

[0156] S3: Dissolve 10g of m-phenylenediamine in 76g of water, then add 2.5g of N,N-dimethylacetamide, 0.35g of sodium hydroxide, 0.35g of sodium lauryl sulfonate, 2.5g of citric acid, 3g of silver nanoparticles and 3g of N-methylpyrrolidone in sequence to obtain an aqueous solution. Coat the aqueous solution containing amine compounds uniformly onto the porous support composite substrate obtained in step S2 by contact coating, and place it in a vacuum oven at 60℃ for 3min to remove surface moisture.

[0157] S4: Take 3g of benzene disulfonyl chloride and 86g of cyclohexane, mix them to obtain an oil phase solution, and uniformly coat the oil phase solution containing acyl chloride compounds onto the membrane obtained in step S3 by contact coating. After completion, dry at 60℃ for 5min to obtain a reverse osmosis composite membrane.

[0158] Comparative Example 2

[0159] A method for preparing a high-temperature resistant reverse osmosis membrane includes the following steps:

[0160] S1: Take 12g of solid polysulfone and 2g of fumed silica with an average particle size of 6-8nm and place them in 80g of N,N-dimethylformamide. Then add 2g of polyethylene glycol and mix evenly. Let stand for 10s, degas and filter to obtain casting solution.

[0161] S2: The casting solution is uniformly extruded and coated onto the polyester nonwoven fabric. After standing for 10 seconds, a film is obtained. Then, it is placed in an 8°C water coagulation solution to obtain a porous support composite base film.

[0162] S3: Dissolve 10g of m-phenylenediamine in 76g of water, then add 2.5g of N,N-dimethylacetamide, 0.35g of sodium hydroxide, 0.35g of sodium lauryl sulfonate, 2.5g of citric acid, 3g of silver nanoparticles and 3g of N-methylpyrrolidone in sequence to obtain an aqueous solution. Coat the aqueous solution containing amine compounds uniformly onto the porous support composite substrate obtained in step S2 by contact coating, and place it in a vacuum oven at 60℃ for 3min to remove surface moisture.

[0163] S4: Take 3g of benzene disulfonyl chloride and 86g of cyclohexane, mix them to obtain an oil phase solution, and uniformly coat the oil phase solution containing acyl chloride compounds onto the membrane obtained in step S3 by contact coating. After completion, dry at 60℃ for 5min to obtain a reverse osmosis composite membrane.

[0164] Comparative Example 3

[0165] A method for preparing a high-temperature resistant reverse osmosis membrane includes the following steps:

[0166] S1: Take 12g of solid polysulfone and 10g of bismaleimide resin and place them in 80g of N,N-dimethylformamide, then add 2g of polyethylene glycol and mix well. Let stand for 10s, degas and filter to obtain casting solution.

[0167] S2: The casting solution is uniformly extruded and coated onto the polyester nonwoven fabric. After standing for 10 seconds, a film is obtained. Then, it is placed in an 8°C water coagulation solution to obtain a porous support composite base film.

[0168] S3: Dissolve 10g of m-phenylenediamine in 76g of water, then add 2.5g of N,N-dimethylacetamide, 0.35g of sodium hydroxide, 0.35g of sodium lauryl sulfonate, 2.5g of citric acid, 3g of silver nanoparticles and 3g of N-methylpyrrolidone in sequence to obtain an aqueous solution. Coat the aqueous solution containing amine compounds uniformly onto the porous support composite substrate obtained in step S2 by contact coating, and place it in a vacuum oven at 60℃ for 3min to remove surface moisture.

[0169] S4: Take 3g of benzene disulfonyl chloride and 86g of cyclohexane, mix them to obtain an oil phase solution, and uniformly coat the oil phase solution containing acyl chloride compounds onto the membrane obtained in step S3 by contact coating. After completion, dry at 60℃ for 5min to obtain a reverse osmosis composite membrane.

[0170] Performance testing

[0171] The composite reverse osmosis membranes of Examples 1-19 and Comparative Examples 1-3 were tested for desalination and water permeation performance by continuous operation for 72 hours in a 2000 ppm sodium chloride solution at three operating temperatures of 25, 50, and 85°C and an operating pressure of 1.55 MPa. The results are shown in Table 1.

[0172] Table 1 Performance Test Results

[0173]

[0174]

[0175] Referring to Table 1, the high-temperature resistant reverse osmosis membranes were tested for desalination and water permeability after continuous operation at 25, 50, and 85°C for 72 hours. Compared with Comparative Examples 1 to 3, the high-temperature resistant reverse osmosis composite membranes in Examples 1 to 5 showed a small change in desalination rate as the test temperature increased, and maintained a consistently high desalination rate. In contrast, the desalination rate of the reverse osmosis composite membrane in Comparative Example 1 decreased significantly with increasing treatment temperature. The comparison shows that the high-temperature resistant reverse osmosis composite membrane consistently maintains a relatively high desalination rate and water flux. Furthermore, the reverse osmosis composite membrane did not deform, break, or peel off during high-temperature operation, effectively improving its excellent heat resistance and mechanical properties.

[0176] Compared with Examples 6-9, the proper blending of bismaleimide resin and fumed silica can effectively improve the desalination rate and heat resistance of the high-temperature resistant reverse osmosis composite membrane. When operating at higher temperatures, the water flux increases significantly while the desalination rate changes little. This indicates that the reverse osmosis composite membranes prepared in Examples 6 and 9 have higher heat resistance and more stable water quality during operation, making them more suitable for large-scale stable industrial production and ensuring water production efficiency.

[0177] Analysis suggests that when the mass ratio of bismaleimide resin to fumed silica is greater than 5, the fumed silica cannot completely undergo cross-linking and interpenetration reactions within the resulting mixed bismaleimide resin. Instead, some of it disperses in the porous separation layer with weaker intermolecular forces, affecting heat resistance and consequently the desalination rate. Conversely, when the ratio is less than 2, the proportion of bismaleimide resin in the porous support layer decreases, while the relative amount of fumed silica increases, reducing heat stability. Furthermore, water permeability increases with temperature, which in turn increases the diffusion rate of solutes in aqueous solutions, making it easier for solutes to permeate through the membrane and reducing salt rejection. Fumed silica further increases the water flux of the membrane, making it difficult to guarantee the required salt removal rate. Therefore, these mixing ratios are unsuitable and not recommended.

[0178] Comparing Examples 3 and 14-19, it is evident that the interaction between silver nanoparticles and the mercaptosilane coupling agent significantly affects the water flux of the functional layer, promotes the bonding between the functional layer and the porous support layer, and thus increases the desalination rate and water flux of the high-temperature resistant reverse osmosis composite membrane. The higher desalination rate of the high-temperature resistant reverse osmosis composite membrane in Example 19 compared to Examples 14-18 can be attributed to the silver nanoparticles being embedded in the functional layer undergoing interfacial polymerization through their interaction with the mercaptosilane coupling agent. This increases the water flux of the reverse osmosis membrane while effectively preventing the loss of nano-silver in the water, thereby increasing the cross-linking between the functional layer and the porous support layer and effectively improving the membrane's thermal stability.

[0179] Combining Examples 6 and 12-13, coating the surface of the high-temperature resistant reverse osmosis composite membrane with polyvinyl alcohol can form an antifouling layer on the surface of the functional layer, while improving the hydrophilicity and chlorine resistance of the reverse osmosis composite membrane. This allows the high-temperature resistant reverse osmosis composite membrane to have good durability while maintaining high flux and rejection rate.

[0180] The embodiments described above are some, but not all, embodiments of the present invention. The detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A method for preparing a high-temperature resistant reverse osmosis membrane, characterized in that, Includes the following steps: S1: Preparation of casting solution: The casting solution includes 8-14 parts by weight of solid polysulfone, 5-10 parts by weight of bismaleimide resin, 1-3 parts by weight of fumed silica, 75-82 parts by weight of N,N-dimethylformamide and 0.5-3 parts by weight of pore-forming agent. The above raw materials are mixed and allowed to stand, and then degassed and filtered to obtain the casting solution; S2: The casting solution is uniformly coated on the porous substrate membrane, and the membrane obtained after standing is placed in the aqueous coagulation solution to obtain the porous supported composite substrate membrane; S3: The porous support composite substrate membrane is coated with an aqueous solution containing amine compounds and then dried. S4: The membrane obtained in step S3 is coated with an oil phase solution containing acyl chloride compounds to form a functional layer, and then dried to obtain a reverse osmosis composite membrane; the aqueous phase solution includes the following components in parts by weight: 4-12 parts diamine, 0.5-3 parts silver nanoparticles, 2-2.5 parts pH adjuster, 0.15-0.45 parts surfactant, 0.15-1.2 parts acid acceptor, 2-4 parts modifier, 1-2.5 parts N,N-dimethylacetamide and 72-78 parts pure water, and the casting solution also includes 1-3 parts by weight of mercaptosilane coupling agent.

2. The method for preparing a high-temperature resistant reverse osmosis membrane according to claim 1, characterized in that, The average particle size of the fumed silica is 6-8 nm.

3. The method for preparing a high-temperature resistant reverse osmosis membrane according to claim 1, characterized in that, The mass ratio of the bismaleimide resin to fumed silica is (2-5):

1.

4. The method for preparing a high-temperature resistant reverse osmosis membrane according to claim 1, characterized in that, The diamine is one or more of m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, 4-chloro-1,3-phenylenediamine, and dimethylphenylenediamine; the pH adjuster is one or more of camphor sulfonic acid, tannic acid, and citric acid; the surfactant is one or more of sodium dodecyl sulfonate, sodium dodecylbenzene sulfonate, sodium lauryl sulfonate, and sodium glycocholate; the acid acceptor is sodium hydroxide; and the modifier is N-methylpyrrolidone.

5. The method for preparing a high-temperature resistant reverse osmosis membrane according to claim 1, characterized in that, The oil phase solution comprises 1-4 parts by weight of acyl chloride monomer and 80-88 parts by weight of oil phase solvent. The acyl chloride monomer is one or more of pyromellitic tricarboxylic acid chloride, 4,4'-biphenyl dicarboxylic acid chloride, benzene disulfonyl chloride, and terephthaloyl chloride. The oil phase solvent is one or more of n-hexane, cyclohexane, or heptane.

6. The method for preparing a high-temperature resistant reverse osmosis membrane according to claim 1, characterized in that, The mercaptosilane coupling agent is γ-mercaptopropyltrimethoxysilane or γ-mercaptopropyltriethoxysilane.

7. The method for preparing a high-temperature resistant reverse osmosis membrane according to claim 1, characterized in that, The pore-forming agent is selected from one or more of polyethylene glycol, polyvinylpyrrolidone, and 1,4-dioxane.

8. The method for preparing a high-temperature resistant reverse osmosis membrane according to claim 1, characterized in that, The temperature range of the aqueous coagulation solution is 8-16℃.

9. The method for preparing a high-temperature resistant reverse osmosis membrane according to claim 1, characterized in that, After step S4, the resulting reverse osmosis membrane is first washed with pure water, wetted with glycerin, and then coated with PVA on the surface of the composite membrane, followed by drying at 60-80℃.

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