Preparation method of separation membrane, separation membrane and application of separation membrane

Abstract

The invention provides a preparation method of a separation membrane, the separation membrane and application of the separation membrane, and particularly relates to the technical field of separation membrane preparation. The preparation method of the separation membrane comprises the following steps: dipping a porous base membrane in a water phase solution for 30-90 seconds, taking out the porous base membrane, removing a water phase from the surface, coating one side surface with an oil phase solution, standing for 10-30 seconds, and feeding into heating equipment for polymerization reaction to obtain the separation membrane, wherein the water phase solution and / or the oil phase solution contains at least one additive; the additive comprises at least one of a phase transfer catalyst, a reaction catalyst and a selective conversion catalyst. According to the preparation method, by introducing the additive, the diffusion time of the monomers in the water phase is effectively shortened, and the difference of the concentrations of the monomers in the water phase among the areas of the interface is reduced, so that the polymerization reaction rate of the interface is improved, a more compact separation membrane desalination layer structure is favorably formed, the size of intermolecular pores is reduced, and the maximum pore diameter is remarkably reduced.

Description

Technical Field

[0001] This invention relates to the field of separation membrane preparation technology, and in particular to a method for preparing a separation membrane, the separation membrane itself, and its applications. Background Technology

[0002] Membrane separation technology is widely used in seawater desalination, wastewater treatment, and drinking water purification. The core of nanofiltration and reverse osmosis membranes is the polyamide (PA) separation layer, typically prepared by polymerizing m-phenylenediamine (MPD) and trimesoyl chloride (TMC) at the water-oil interface. In this process, MPD needs to diffuse from the porous base membrane pores to the interface to participate in the reaction. However, due to the uneven distribution of pores in the base membrane and the slow diffusion rate of MPD in the aqueous phase, the monomer concentration varies greatly across different regions of the interface, leading to uneven polymerization and the formation of large and widely distributed intermolecular pores, which affects the membrane's selectivity.

[0003] Furthermore, the accumulation of the reaction byproduct HCl inhibits MPD activity, reduces crosslinking degree, and further exacerbates pore defects. Existing improvement methods include adding co-solvents, surfactants, acid-binding agents, or performing post-treatment chain extension to improve mass transfer efficiency, neutralize acidic environments, or achieve secondary crosslinking. However, these methods are mostly single-function regulation, making it difficult to synergistically solve problems such as uneven diffusion and reaction imbalance, and they lack the ability to precisely adjust sub-nanometer pore sizes.

[0004] Therefore, there is an urgent need for a simple and effective method that can achieve uniform reduction of the pore size of the separation layer, especially the reduction of the maximum pore size, during conventional membrane fabrication processes.

[0005] In view of this, the present invention is hereby proposed. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing a separation membrane, the separation membrane itself, and its application, thereby addressing at least one of the aforementioned technical problems in the prior art.

[0007] In order to achieve the above-mentioned objectives of the present invention, the following technical solution is adopted: The first aspect of the present invention provides a method for preparing a separation membrane, comprising the following steps: immersing a porous base membrane in an aqueous solution for 30-90 seconds, removing it and removing the aqueous phase from its surface, then coating one side of the membrane with an oil solution, allowing it to stand for 10-30 seconds, and then feeding it into a heating device for a polymerization reaction to obtain the separation membrane; wherein the aqueous solution and / or the oil solution contain at least one additive; the additive includes at least one of a phase transfer catalyst, a reaction catalyst, and a selective conversion catalyst.

[0008] Furthermore, the phase transfer catalyst comprises an amphiphilic compound.

[0009] Preferably, the amphiphilic compound includes at least one of stearic acid, oleic acid, triethanolamine soap, sodium glycocholate, and sodium dioctyl succinate sulfonate, and more preferably sodium dioctyl succinate sulfonate.

[0010] Preferably, the phase transfer catalyst is added to the aqueous solution.

[0011] Preferably, the concentration of the phase transfer catalyst in the aqueous solution is 0.1~1.0 wt%.

[0012] Furthermore, the reaction catalyst includes phosphoric acid catalysts and / or metal catalysts.

[0013] Furthermore, the phosphoric acid catalyst includes phosphoric acid and / or phosphorous acid.

[0014] Preferably, the phosphoric acid catalyst is added to the aqueous solution.

[0015] Preferably, the concentration of the phosphoric acid catalyst in the aqueous solution is 1-5 wt%.

[0016] Furthermore, the metal catalyst comprises at least one of titanate compounds, zirconate compounds, or tin compounds.

[0017] Preferably, the metal catalyst is added to the oil phase solution.

[0018] Preferably, the concentration of the metal catalyst in the oil phase solution is 0.05~0.5wt%.

[0019] Preferably, the tin compound includes dibutyltin dilaurate at a concentration of 0.1 to 0.3 wt%.

[0020] Furthermore, the selective conversion catalyst comprises methylpyridine tertiary amine compounds, cyclic pyridine tertiary amine compounds, or a mixture of potassium hydroxide and crown ether compounds.

[0021] Preferably, the selective conversion catalyst is added to the oil phase solution.

[0022] Preferably, the methylpyridine tertiary amine compound includes at least one of 1,3,5-trimethyl-2-pyridine tertiary amine, 4-(N,N-dimethylamino)pyridine, and 2-(dialkylaminomethyl)pyridine.

[0023] Preferably, the cyclic pyridine tertiary amine compound includes at least one of 2-(1-piperidinemethyl)pyridine, 2-(4-morpholinomethyl)pyridine, and 4-(1-piperidinemethyl)pyridine.

[0024] Preferably, the crown ether compound includes at least one of 12-crown-4, 15-crown-5, and 18-crown-6.

[0025] Preferably, the methylpyridine tertiary amine compound is 1,3,5-trimethyl-2-pyridine tertiary amine, with a concentration of 0.5~1.5 wt%.

[0026] Furthermore, the porous base membrane includes at least one of polyacrylonitrile membrane, nitrocellulose membrane, polyamide membrane, polyetherketone membrane, polysulfone membrane, and polyethersulfone membrane.

[0027] Preferably, the polymerization reaction is carried out at a temperature of 60-80°C for 100-150 seconds.

[0028] Preferably, the aqueous solution comprises an aqueous monomer and water.

[0029] Preferably, the aqueous monomer comprises m-phenylenediamine.

[0030] Preferably, the concentration of the aqueous monomer is 1~5wt%.

[0031] Preferably, the oil phase solution includes an oil phase monomer and a solvent.

[0032] Preferably, the oil phase monomer comprises pyromellitic acid trimethylolpropionate (PMT).

[0033] Preferably, the concentration of the oil phase monomer is 0.5~1.0 wt%.

[0034] Preferably, the solvent includes at least one selected from n-hexane, cyclohexane, and heptane.

[0035] Furthermore, the preparation method also includes a post-treatment process after the polymerization reaction, wherein the post-treatment process involves immersing the polymerized membrane in a post-treatment solution for further reaction.

[0036] Preferably, the reaction temperature is 60~120℃ and the time is 0.5~4h.

[0037] Preferably, the post-treatment solution includes a chain extender, a chain extender catalyst, and a solvent.

[0038] Preferably, the chain extender comprises at least one of hexamethylene diisocyanate, 4,4'-diphenylmethane diisocyanate, pyromellitic dianhydride, maleic anhydride, or glycidyl ether compounds.

[0039] Preferably, the concentration of the chain extender is 1-5 wt%.

[0040] Preferably, the chain extender catalyst comprises dibutyltin dilaurate.

[0041] Preferably, the concentration of the chain extender catalyst is 0.1~1.0 wt%.

[0042] Preferably, the solvent includes at least one selected from n-hexane, cyclohexane, and heptane.

[0043] A second aspect of the present invention provides a separation membrane prepared using the preparation method described in the first aspect.

[0044] A third aspect of the present invention provides an application of the separation membrane described above in the fields of seawater desalination, drinking water purification, industrial wastewater treatment, or pharmaceutical purification.

[0045] Compared with the prior art, the present invention has at least the following beneficial effects: The preparation method provided by this invention effectively shortens the diffusion time of monomers in the aqueous phase by introducing additives, reduces the difference in monomer concentration between different regions of the interface, thereby increasing the interfacial polymerization reaction rate. This helps to form a denser desalination layer structure in the separation membrane, reduces the intermolecular pore size, and significantly reduces the maximum pore diameter. Furthermore, by grafting and modifying the effective functional groups in the separation layer through subsequent processing, the microstructure of the desalination layer is further controlled, achieving precise control of pore size, reducing the intermolecular porosity of the desalination layer, and lowering the maximum pore diameter in the desalination layer to 1.68 nm, thus synergistically improving the separation performance and selectivity of the separation membrane.

[0046] The separation membrane provided by this invention features a more uniform pore size distribution in the desalination layer, with the overall pore size range controllable between 0.8 and 1.68 nm, achieving precise sub-nanometer-level control. This separation membrane exhibits superior retention performance, achieving near-complete retention of hydrophilic organic compounds with molecular weights as low as approximately 350 Da, while maintaining good flux characteristics.

[0047] The separation membrane provided by this invention has broad application prospects in seawater desalination, drinking water purification, industrial wastewater treatment and pharmaceutical purification. With its excellent separation ability and selectivity, it significantly improves the efficiency and accuracy of substance separation in related fields, provides high-performance separation membrane support for downstream applications, and strongly promotes the technological progress and development of the above-mentioned industries. Attached Figure Description

[0048] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0049] Figure 1 This is a schematic diagram of the preparation method of the separation membrane; Figure 2 This is a device for testing the separation capacity of separation membranes.

[0050] Icons: 1-Test liquid tank; 2-Booster pump; 3-Stop valve; 4-Pressure gauge; 5-Separation membrane; 6-Separation membrane evaluation tank; 7-Permeate outlet; 8-Pressure gauge; 9-Stop valve; 10-Flow meter; 11-Temperature control system; 12-Online temperature instrument. Detailed Implementation

[0051] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0052] In the following, the terms “comprising,” “having,” and their cognates, which may be used in various embodiments of the invention, are intended only to indicate a particular feature, number, step, operation, element, component, or combination thereof, and should not be construed as excluding, firstly, the presence of one or more other features, numbers, steps, operations, elements, components, or combinations thereof, or adding the possibility of one or more features, numbers, steps, operations, elements, components, or combinations thereof.

[0053] The first aspect of the present invention provides a method for preparing a separation membrane, such as... Figure 1 As shown, the process includes the following steps: immersing a porous base membrane in an aqueous solution for 30-90 seconds, removing it and removing the aqueous phase from its surface, then coating one side of the surface with an oil solution, allowing it to stand for 10-30 seconds, and then feeding it into a heating device for polymerization reaction. Finally, after post-treatment, a polyamide separation layer is formed, resulting in the separation membrane. The aqueous solution and / or the oil solution contain at least one additive; the additive includes at least one of a phase transfer catalyst, a reaction catalyst, and a selective conversion catalyst.

[0054] The preparation method provided by this invention effectively shortens the diffusion time of monomers in the aqueous phase by introducing additives, reduces the difference in monomer concentration between different regions of the interface, thereby increasing the interfacial polymerization reaction rate. This helps to form a denser desalination layer structure in the separation membrane, reduces the intermolecular pore size, and significantly reduces the maximum pore diameter. Furthermore, by grafting and modifying the effective functional groups in the separation layer through subsequent processing, the microstructure of the desalination layer is further controlled, achieving precise control of pore size, reducing the intermolecular porosity of the desalination layer, and lowering the maximum pore diameter in the desalination layer to 1.68 nm, thus synergistically improving the separation performance and selectivity of the separation membrane.

[0055] Typically, but not limitingly, the time for immersing the porous membrane in the aqueous solution can be, for example, 30 s, 45 s, 60 s, 75 s, or 90 s, or any value within the range of 30 s to 90 s; after removal, the aqueous phase is removed from the surface, and then an oil phase solution is coated on one side of the surface, and the standing time can be, for example, 10 s, 15 s, 20 s, 25 s, or 30 s, or any value within the range of 10 s to 30 s.

[0056] Furthermore, the phase transfer catalyst includes an amphiphilic compound whose molecular structure contains both hydrophilic and hydrophobic groups. This effectively reduces the interfacial tension between the aqueous and oil phases, promoting faster and more uniform diffusion of monomers (such as m-phenylenediamine) from the aqueous phase to the water-oil interface. Through this effect, the amphiphilic compound not only shortens the monomer diffusion time but also reduces the monomer concentration differences between different regions of the interface caused by uneven diffusion. This improves the uniformity and rate of the interfacial polymerization reaction, contributing to the formation of a denser polyamide desalination layer with smaller pore sizes. Ultimately, this allows for precise control of the separation membrane's microstructure, improving its selectivity and separation performance.

[0057] Preferably, the amphiphilic compound includes at least one of stearic acid, oleic acid, triethanolamine soap, sodium glycocholate, and sodium dioctyl succinate sulfonate, and more preferably sodium dioctyl succinate sulfonate.

[0058] Preferably, the phase transfer catalyst is added to the aqueous solution.

[0059] Preferably, the concentration of the phase transfer catalyst in the aqueous solution is 0.1~1.0 wt%.

[0060] Typically, but not limitingly, the concentration of the phase transfer catalyst in the aqueous solution can be, for example, 0.1 wt%, 0.2 wt%, 0.4 wt%, 0.6 wt%, 0.8 wt%, or 1.0 wt%, or any value in the range of 0.1 wt% to 1.0 wt%.

[0061] Furthermore, the reaction catalyst includes phosphoric acid catalysts and / or metal catalysts.

[0062] Phosphoric acid catalysts, when added to the aqueous solution, can promote the activity of aqueous monomers and enhance their reaction rate with oil monomers at the interface by providing protons or adjusting the local pH environment. Metal catalysts, typically added to the oil solution, activate acyl chloride groups in the oil phase using their Lewis acid properties, increasing their electrophilicity and thus accelerating the condensation reaction with amine groups in the aqueous phase. Both catalysts, acting synergistically or individually, can effectively improve the kinetic efficiency of interfacial polymerization reactions, promote the formation of a more cross-linked and denser polyamide separation layer, help reduce membrane pore size and maximum pore diameter, and thereby optimize membrane retention performance and selectivity.

[0063] Furthermore, the phosphoric acid catalyst includes phosphoric acid and / or phosphorous acid.

[0064] Preferably, the phosphoric acid catalyst is added to the aqueous solution.

[0065] Preferably, the concentration of the phosphoric acid catalyst in the aqueous solution is 1-5 wt%.

[0066] Typically, but not limitingly, the concentration of the phosphoric acid catalyst in the aqueous solution can be, for example, 1 wt%, 2 wt%, 3 wt%, 4 wt%, or 5 wt%, or any value within the range of 1 wt% to 5 wt%.

[0067] Furthermore, the metal catalyst comprises at least one of titanate compounds, zirconate compounds, or tin compounds.

[0068] Preferably, the metal catalyst is added to the oil phase solution.

[0069] Preferably, the concentration of the metal catalyst in the oil phase solution is 0.05~0.5wt%.

[0070] Typically, but not limitingly, the concentration of the metal catalyst in the oil phase solution can be, for example, 0.05 wt%, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, or 0.5 wt%, or any value in the range of 0.05 wt% to 0.5 wt%.

[0071] Preferably, the tin compound includes dibutyltin dilaurate at a concentration of 0.1 to 0.3 wt%.

[0072] Typically, but not limitingly, the concentration of dibutyltin dilaurate can be, for example, 0.1 wt%, 0.15 wt%, 0.2 wt%, 0.25 wt%, or 0.3 wt%, or any value in the range of 0.1 wt% to 0.3 wt%.

[0073] Furthermore, the selective conversion catalyst comprises methylpyridine tertiary amine compounds, cyclic pyridine tertiary amine compounds, or a mixture of potassium hydroxide and crown ether compounds.

[0074] Methylpyridine tertiary amines and cyclic pyridine tertiary amines, acting as organic bases, can effectively neutralize the reaction byproduct HCl, inhibiting its inhibitory effect on the activity of amine monomers, while simultaneously promoting nucleophilic attack of acyl chloride groups, thus increasing the reaction rate and crosslinking degree. Meanwhile, mixtures of potassium hydroxide and crown ether compounds selectively transfer OH⁻ ions from the aqueous phase to the interfacial region by forming crown ether-cation complexes, locally increasing interfacial basicity, enhancing deprotonation ability, and thereby promoting the nucleophilicity of amine groups and accelerating amide bond formation. These catalysts not only improve the uniformity of the reaction environment but also achieve selective control of reaction sites and pathways, contributing to the formation of more uniform polyamide desalination layers with narrower pore sizes, significantly improving the separation accuracy and performance stability of the separation membrane.

[0075] Preferably, the selective conversion catalyst is added to the oil phase solution.

[0076] Preferably, the methylpyridine tertiary amine compound includes at least one of 1,3,5-trimethyl-2-pyridine tertiary amine, 4-(N,N-dimethylamino)pyridine, and 2-(dialkylaminomethyl)pyridine.

[0077] Preferably, the cyclic pyridine tertiary amine compound includes at least one of 2-(1-piperidinemethyl)pyridine, 2-(4-morpholinomethyl)pyridine, and 4-(1-piperidinemethyl)pyridine.

[0078] Preferably, the crown ether compound includes at least one of 12-crown-4, 15-crown-5, and 18-crown-6.

[0079] Preferably, the methylpyridine tertiary amine compound is 1,3,5-trimethyl-2-pyridine tertiary amine, with a concentration of 0.5~1.5 wt%.

[0080] Typically, but not limitingly, the concentration of the 1,3,5-trimethyl-2-pyridine tertiary amine can be, for example, 0.5 wt%, 0.8 wt%, 1.0 wt%, 1.2 wt%, or 1.5 wt%, or any value in the range of 0.5 wt% to 1.5 wt%.

[0081] Furthermore, the porous base membrane includes at least one of polyacrylonitrile membrane, nitrocellulose membrane, polyamide membrane, polyetherketone membrane, polysulfone membrane, and polyethersulfone membrane.

[0082] Preferably, the polymerization reaction is carried out at a temperature of 60-80°C for 100-150 seconds.

[0083] Typically, but not limitingly, the temperature of the polymerization reaction can be, for example, 60°C, 65°C, 70°C, 75°C or 80°C, or any value within the range of 60°C to 80°C; the time of the polymerization reaction can be, for example, 100s, 120s, 130s, 140s or 150s, or any value within the range of 100s to 150s.

[0084] Preferably, the aqueous solution comprises an aqueous monomer and water.

[0085] Preferably, the aqueous monomer comprises m-phenylenediamine.

[0086] Preferably, the concentration of the aqueous monomer is 1~5wt%.

[0087] Typically, but not limitingly, the concentration of the aqueous monomer can be, for example, 1 wt%, 2 wt%, 3 wt%, 4 wt%, or 5 wt%, or any value within the range of 1 wt% to 5 wt%.

[0088] Preferably, the oil phase solution includes an oil phase monomer and a solvent.

[0089] Preferably, the oil phase monomer comprises pyromellitic acid trimethylolpropionate (PMT).

[0090] Preferably, the concentration of the oil phase monomer is 0.5~1.0 wt%.

[0091] Typically, but not limitingly, the concentration of the oil phase monomer can be, for example, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, or 1.0 wt%, or any value in the range of 0.5 wt% to 1.0 wt%.

[0092] Preferably, the solvent includes at least one selected from n-hexane, cyclohexane, and heptane.

[0093] Furthermore, the preparation method also includes a post-treatment process after the polymerization reaction, wherein the post-treatment process involves immersing the polymerized membrane in a post-treatment solution for further reaction.

[0094] Preferably, the reaction temperature is 60~120℃ and the time is 0.5~4h.

[0095] Typically, but not limitingly, the temperature of the reaction can be, for example, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, or 120°C, or any value within the range of 60°C to 120°C; the reaction time can be, for example, 0.5 h, 1 h, 2 h, 3 h, or 4 h, or any value within the range of 0.5 h to 4 h.

[0096] Preferably, the post-treatment solution includes a chain extender, a chain extender catalyst, and a solvent. The post-treatment process is used to chemically graft and modify the structure of the formed polyamide separation layer. This process involves immersing the membrane in a solution containing a chain extender and a chain extender catalyst, and under heating conditions, initiating a further reaction between residual functional groups (such as amine or carboxyl groups) and the chain extender (such as diisocyanate, acid anhydride, etc.), thereby achieving secondary crosslinking or chain segment extension of the polymer network. This reaction can effectively end unreacted active groups, reduce defect sites, and further densify the desalination layer structure, reducing the intermolecular pore size and its distribution width. Simultaneously, the post-treatment can improve the crosslinking degree and stability of the membrane, synergistically reducing the maximum pore size to the sub-nanometer level, thereby significantly enhancing the separation membrane's ability to retain small molecule organic matter.

[0097] Preferably, the chain extender comprises at least one of hexamethylene diisocyanate, 4,4'-diphenylmethane diisocyanate, pyromellitic dianhydride, maleic anhydride, or glycidyl ether compounds.

[0098] Preferably, the concentration of the chain extender is 1-5 wt%.

[0099] Typically, but not limitingly, the concentration of the chain extender can be, for example, 1 wt%, 2 wt%, 3 wt%, 4 wt%, or 5 wt%, or any value in the range of 1 wt% to 5 wt%.

[0100] Preferably, the chain extender catalyst comprises dibutyltin dilaurate.

[0101] Preferably, the concentration of the chain extender catalyst is 0.1~1.0 wt%.

[0102] Typically, but not limitingly, the concentration of the chain extender catalyst may be, for example, 0.1 wt%, 0.2 wt%, 0.4 wt%, 0.6 wt%, 0.8 wt%, or 1.0 wt%, or any value in the range of 0.1 wt% to 1.0 wt%. Preferably, the solvent includes at least one of n-hexane, cyclohexane, and heptane.

[0103] A second aspect of the present invention provides a separation membrane prepared using the preparation method described in the first aspect.

[0104] The separation membrane provided by this invention features a more uniform pore size distribution in the desalination layer, with the overall pore size range controllable between 0.8 and 1.68 nm, achieving precise sub-nanometer-level control. This separation membrane exhibits superior retention performance, achieving near-complete retention of hydrophilic organic compounds with molecular weights as low as approximately 350 Da, while maintaining good flux characteristics.

[0105] A third aspect of the present invention provides an application of the separation membrane described above in the fields of seawater desalination, drinking water purification, industrial wastewater treatment, or pharmaceutical purification.

[0106] The separation membrane provided by this invention has broad application prospects in seawater desalination, drinking water purification, industrial wastewater treatment and pharmaceutical purification. With its excellent separation ability and selectivity, it significantly improves the efficiency and accuracy of substance separation in related fields, provides high-performance separation membrane support for downstream applications, and strongly promotes the technological progress and development of the above-mentioned industries.

[0107] The present invention is further illustrated below with specific embodiments and comparative examples. However, it should be understood that these embodiments are merely for illustrative purposes and should not be construed as limiting the invention in any way. Unless otherwise specified, the raw materials used in the embodiments and comparative examples of the present invention were carried out under conventional conditions or conditions recommended by the manufacturer. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products.

[0108] Example 1 This embodiment provides a method for preparing a separation membrane, the specific steps of which are as follows: 1. Immerse the polysulfone-based membrane in an aqueous solution for 60 seconds, then gently remove the surface aqueous phase using a scraper or air knife, and then coat the surface with an oil solution and let it stand for 20 seconds.

[0109] The aqueous phase solution contains 3 wt% m-phenylenediamine (MPD), 0.5 wt% sodium dioctyl succinate sulfonate (AOT), and 2 wt% phosphoric acid, with the balance being water; the oil phase solution contains 0.8 wt% trimesoyl chloride (TMC), 0.9 wt% 1,3,5-trimethyl-2-pyridine tertiary amine, with the balance being n-hexane.

[0110] 2. The coated base film is placed in a 70℃ oven and dried for 120 seconds to obtain the separation membrane.

[0111] Example 2 This embodiment provides a method for preparing a separation membrane, the specific steps of which are as follows: 1. Immerse the polysulfone-based membrane in an aqueous solution for 60 seconds, then gently remove the surface aqueous phase using a scraper or air knife, and then coat the surface with an oil solution and let it stand for 20 seconds.

[0112] The aqueous phase solution contains 3 wt% m-phenylenediamine (MPD) and 0.5 wt% sodium dioctyl succinate sulfonate (AOT), with the remainder being water; the oil phase solution contains 0.8 wt% trimesoyl chloride (TMC), with the remainder being n-hexane.

[0113] 2. The coated base film is placed in a 70℃ oven and dried for 120 seconds to obtain the separation membrane.

[0114] Example 3 This embodiment provides a method for preparing a separation membrane, the specific steps of which are as follows: 1. Immerse the polysulfone-based membrane in an aqueous solution for 60 seconds, then gently remove the surface aqueous phase using a scraper or air knife, and then coat the surface with an oil solution and let it stand for 20 seconds.

[0115] The aqueous phase solution contains 3 wt% m-phenylenediamine (MPD) and 3 wt% phosphoric acid, with the remainder being water; the oil phase solution contains 0.8 wt% trimesoyl chloride (TMC), with the remainder being n-hexane.

[0116] 2. The coated base film is placed in a 70℃ oven and dried for 120 seconds to obtain the separation membrane.

[0117] Example 4 This embodiment provides a method for preparing a separation membrane, the specific steps of which are as follows: 1. Immerse the polysulfone-based membrane in an aqueous solution for 60 seconds, then gently remove the surface aqueous phase using a scraper or air knife, and then coat the surface with an oil solution and let it stand for 20 seconds.

[0118] The aqueous phase solution contains 3 wt% m-phenylenediamine (MPD), with the remainder being water; the oil phase solution contains 0.8 wt% trimesoyl chloride (TMC), 0.2 wt% dibutyltin dilaurate, with the remainder being n-hexane.

[0119] 2. The coated base film is placed in a 70℃ oven and dried for 120 seconds to obtain the separation membrane.

[0120] Example 5 This embodiment provides a method for preparing a separation membrane, the specific steps of which are as follows: 1. Immerse the polysulfone-based membrane in an aqueous solution for 60 seconds, then gently remove the surface aqueous phase using a scraper or air knife, and then coat the surface with an oil solution and let it stand for 20 seconds.

[0121] The aqueous solution contains 3 wt% m-phenylenediamine (MPD), with the remainder being water; the oil solution contains 0.8 wt% trimesoyl chloride (TMC), 0.9 wt% 1,3,5-trimethyl-2-pyridine tertiary amine, with the remainder being n-hexane.

[0122] 2. The coated base film is placed in a 70℃ oven and dried for 120 seconds to obtain the separation membrane.

[0123] Example 6 This embodiment provides a method for preparing a separation membrane, the specific steps of which are as follows: 1. Immerse the polysulfone-based membrane in an aqueous solution for 60 seconds, then gently remove the surface aqueous phase using a scraper or air knife, and then coat the surface with an oil solution and let it stand for 20 seconds.

[0124] The aqueous phase solution contains 3 wt% m-phenylenediamine (MPD), with the remainder being water; the oil phase solution contains 0.8 wt% trimesoyl chloride (TMC), with the remainder being n-hexane.

[0125] 2. The coated base film is dried in a 70℃ oven for 120 seconds. Finally, the membrane is immersed in a 100℃ post-treatment solution for 2 hours to obtain the separation membrane.

[0126] The post-treatment solution contains 2 wt% hexamethylene diisocyanate (HDI), 0.3 wt% dibutyltin dilaurate, and n-hexane as the solvent.

[0127] Comparative Example 1 This comparative example provides a method for preparing a separation membrane, the specific steps of which are as follows: 1. Immerse the polysulfone-based membrane in an aqueous solution for 60 seconds, then gently remove the surface aqueous phase using a scraper or air knife, and then coat the surface with an oil solution and let it stand for 20 seconds.

[0128] The aqueous phase solution contains 3 wt% m-phenylenediamine (MPD), with the remainder being water; the oil phase solution contains 0.8 wt% trimesoyl chloride (TMC), with the remainder being n-hexane.

[0129] 2. The coated base film is placed in a 70℃ oven and dried for 120 seconds to obtain the separation membrane.

[0130] Test Example 1 The separation capabilities of the separation membranes obtained in the examples and comparative examples were tested. Nearly spherical and hydrophilic organic molecules were used as the test medium, and the aqueous solution was adjusted to pH 7 (the pH corresponding to the isoelectric point of the molecules being non-ionized) and the concentration of the aqueous solution was set to 500 ppm for testing.

[0131] Organic molecules include ethanol, isopropanol, neopentyl alcohol, pentaerythritol, sorbitol, PEG-200, PEG-250 (custom reagent), PEG-300, PEG-350 (custom reagent), PEG-400, PEG-500 (custom reagent) and PEG-600.

[0132] The equipment used in the test, such as Figure 2 As shown, after fixing the membrane in the evaluation tank, start the equipment, adjust the pressure to 100 psi, control the solution temperature at 25°C, pre-pressurize and circulate for 30 min, add permeate for 10 min, and then shut down the equipment. Take samples of the feed solution and membrane permeate to test TOC, calculate the rejection rate, and weigh the permeate to calculate the flux.

[0133] The obtained data is recorded in Table 1.

[0134] Table 1

[0135] As can be seen from Table 1, the blank membrane of Comparative Example 1 can completely retain organic compounds with a molecular weight slightly greater than 600, and has a large retention effect on organic compounds with a molecular weight of 250-600. This indicates that the maximum intermolecular porosity is 1.75 nm and the overall pore size distribution range is 1.3-1.75 nm.

[0136] The membrane provided in Example 1 almost completely retains organic compounds with a molecular weight of 350. The retention rate of organic compounds with a molecular weight range of 136-350 is much higher than that of the blank membrane. This indicates that the maximum intermolecular porosity of the improved membrane is 1.5 nm, the overall pore size distribution range is 0.8-1.5 nm, and the number of pores with different diameters (0.8-1.5 nm) is greater than that of the blank membrane (1.3-1.75 nm). The maximum pore size and the overall pore size are significantly smaller.

[0137] The membrane provided in Example 2 almost completely retains organic compounds with a molecular weight of 400. The retention rate of organic compounds with a molecular weight range of 136-400 is much higher than that of the blank membrane, indicating that the maximum intermolecular porosity of the improved membrane is about 1.6 nm, the overall pore size distribution range is 0.9-1.6 nm, and the number of pores with different diameters (0.9-1.6 nm) is greater than that of the blank membrane (1.3-1.75 nm). The maximum pore size and the overall pore size are significantly smaller.

[0138] The membrane provided in Example 3 completely retains organic compounds with a molecular weight of 500. The retention rate of organic compounds with a molecular weight range of 200-500 is much higher than that of the blank membrane. This indicates that the maximum intermolecular porosity of the improved membrane is 1.68 nm, the overall pore size distribution range is 1.2-1.68 nm, and the number of pores with different diameters (1.2-1.68 nm) is greater than that of the blank membrane (1.3-1.75 nm). The maximum pore size and the overall pore size are significantly smaller.

[0139] The membrane provided in Example 4 almost completely retains organic compounds with a molecular weight of 400. The retention rate of organic compounds with a molecular weight range of 200-400 is much higher than that of the blank membrane. This indicates that the maximum intermolecular porosity of the improved membrane is about 1.6 nm, the overall pore size distribution range is 1.2-1.6 nm, and the number of pores with different diameters (1.2-1.6 nm) is greater than that of the blank membrane (1.3-1.75 nm). The maximum pore size and the overall pore size are significantly smaller.

[0140] The membrane provided in Example 5 basically completely retains organic compounds with a molecular weight of 400. The retention rate of organic compounds with a molecular weight range of 182-400 is much higher than that of the blank membrane. This indicates that the maximum intermolecular porosity of the improved membrane is 1.6 nm, the overall pore size distribution range is 0.9-1.6 nm, and the number of pores with different diameters (0.9-1.6 nm) is greater than that of the blank membrane (1.3-1.75 nm). The maximum pore size and the overall pore size are significantly smaller.

[0141] The membrane provided in Example 6 basically completely retains organic compounds with a molecular weight of 500. The retention rate of organic compounds with a molecular weight range of 200-500 is much higher than that of the blank membrane. This indicates that the maximum intermolecular porosity of the improved membrane is 1.68 nm, the overall pore size distribution range is 1.2-1.68 nm, and the number of pores with different diameters (1.2-1.68 nm) is greater than that of the blank membrane (1.3-1.75 nm). The maximum pore size and the overall pore size are significantly smaller.

[0142] Finally, it should be noted that the above-described embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and not to limit it. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the technical scope disclosed in the present invention, or make equivalent substitutions for some of the technical features; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for producing a separation membrane, characterized by, The method comprises the following steps: immersing the porous base film in an aqueous phase solution for 30-90s, removing the water phase after taking out the film, coating an oil phase solution on one side of the film, standing for 10-30s, and sending the film into a heating device for polymerization to obtain the separation film; The aqueous phase solution and / or the oil phase solution contains at least one additive; The additive comprises at least one of a phase transfer catalyst, a reaction catalyst, and a selective conversion catalyst.

2. The production method according to claim 1, characterized by, The phase transfer catalyst comprises an amphiphilic compound; Preferably, the amphiphilic compound comprises at least one of stearic acid, oleic acid, triethanolamine soap, sodium glycocholate, and dioctyl sodium sulfosuccinate, and is preferably dioctyl sodium sulfosuccinate; Preferably, the phase transfer catalyst is added to the aqueous phase solution; Preferably, the concentration of the phase transfer catalyst in the aqueous phase solution is 0.1-1.0wt%.

3. The preparation method according to claim 1, characterized in that, The reaction catalyst comprises a phosphoric acid catalyst and / or a metal catalyst.

4. The production method according to claim 3, characterized by, The phosphoric acid catalyst comprises phosphoric acid and / or phosphorous acid; Preferably, the phosphoric acid catalyst is added to the aqueous phase solution; Preferably, the concentration of the phosphoric acid catalyst in the aqueous phase solution is 1-5wt%.

5. The preparation method according to claim 3, characterized in that, The metal catalyst is at least one of a titanate compound, a zirconate compound, or a tin compound; Preferably, the metal catalyst is added to the oil phase solution; Preferably, the concentration of the metal catalyst in the oil phase solution is 0.05-0.5wt%. Preferably, the tin compound comprises dibutyltin dilaurate, and the concentration is 0.1-0.3wt%.

6. The method of claim 1, wherein, The selective conversion catalyst comprises at least one of a methylpyridine tertiary amine compound, a cyclic pyridine tertiary amine compound, or a mixture of potassium hydroxide and a crown ether compound; Preferably, the selective conversion catalyst is added to the oil phase solution; Preferably, the methylpyridine tertiary amine compound comprises at least one of 1,3,5-trimethyl-2-pyridine tertiary amine, 4-(N,N-dimethylamino)pyridine, and 2-(dialkylaminomethyl)pyridine; Preferably, the cyclic pyridine tertiary amine compound comprises at least one of 2-(1-piperidinomethyl)pyridine, 2-(4-morpholinomethyl)pyridine, and 4-(1-piperidinomethyl)pyridine; Preferably, the crown ether compound comprises at least one of 12-crown-4, 15-crown-5, and 18-crown-6; Preferably, the methylpyridine tertiary amine compound is 1,3,5-trimethyl-2-pyridine tertiary amine, and the concentration is 0.5-1.5wt%.

7. The method of any one of claims 1 to 6, wherein the method further comprises the step of: The porous base film comprises at least one of a polyacrylonitrile film, a nitrocellulose film, a polyamide film, a polyether ketone film, a polysulfone film, and a polyether sulfone film; Preferably, the temperature of the polymerization is 60-80℃, and the time is 100-150s; Preferably, the aqueous phase solution comprises an aqueous phase monomer and water; Preferably, the aqueous phase monomer comprises m-phenylenediamine; Preferably, the concentration of the aqueous phase monomer is 1-5wt%; Preferably, the oil phase solution comprises an oil phase monomer and a solvent; Preferably, the oil phase monomer comprises trimesoyl chloride; Preferably, the concentration of the oil phase monomer is 0.5-1.0 wt%; Preferably, the solvent comprises at least one of n-hexane, cyclohexane and heptane.

8. The method of any one of claims 1 to 6, wherein the method further comprises the step of: Further comprising a post-treatment process after the polymerization reaction, the post-treatment process is to immerse the film after the polymerization reaction in a post-treatment solution for reaction; Preferably, the temperature of the reaction is 60-120℃, and the time is 0.5-4h; Preferably, the post-treatment solution comprises a chain extender, a chain extension catalyst and a solvent; Preferably, the chain extender comprises at least one of hexamethylene diisocyanate, 4,4'-diphenyl methane diisocyanate, pyromellitic dianhydride, maleic anhydride or glycidyl ether compounds; Preferably, the concentration of the chain extender is 1-5 wt%; Preferably, the chain extension catalyst comprises dibutyl tin dilaurate; Preferably, the concentration of the chain extension catalyst is 0.1-1.0 wt%; Preferably, the solvent comprises at least one of n-hexane, cyclohexane and heptane.

9. A separation membrane, characterized by, Prepared by the preparation method of any one of claims 1-8.

10. Use of the separation membrane of claim 9 in the field of seawater desalination, drinking water purification, industrial wastewater treatment or pharmaceutical purification.

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