A compression-resistant and stain-resistant polyether sulfone ultrafiltration membrane based on in-situ cross-linking and a preparation method thereof

Abstract

The embodiment of the application discloses a compression-resistant and stain-resistant polyether sulfone ultrafiltration membrane based on in-situ cross-linking and a preparation method thereof, and relates to the technical field of separation membrane materials. The ultrafiltration membrane comprises a main body substrate, a three-dimensional semi-interpenetrating network and an amphoteric hydrophilic monomer located inside the main body substrate. The main body substrate is polyether sulfone. The three-dimensional semi-interpenetrating network is formed by in-situ cross-linking of an amino-terminated polyether amine and a hydrophilic epoxy monomer.

Description

Technical Field

[0001] This invention relates to the field of separation membrane material technology, and in particular to a pressure-resistant and dirt-resistant polyethersulfone ultrafiltration membrane based on in-situ crosslinking and its preparation method. Background Technology

[0002] Polyethersulfone (PES) is a high-performance aromatic polymer material. Ultrafiltration membranes made from PES possess excellent chemical stability, moderate mechanical strength, and controllable manufacturing costs, exhibiting outstanding comprehensive performance advantages. They are widely used in membrane separation technology and industrial separation fields, particularly suitable for demanding applications such as industrial high-pressure separation, high-pressure reverse osmosis pretreatment, and biopharmaceutical fluid purification. In the core application of high-pressure reverse osmosis pretreatment systems, PES ultrafiltration membranes, with their excellent solvent resistance and structural stability, can effectively retain suspended solids, colloids, and large organic molecules in the feed liquid. This avoids fouling problems of reverse osmosis membranes under high-pressure operating conditions from the source, ensuring the water production efficiency and operational stability of the reverse osmosis system and extending the service life of the membrane modules. With the rapid development of industrial high-pressure separation technology and the high-pressure reverse osmosis water treatment industry, the requirements for the pressure resistance, separation accuracy, and structural stability of pretreatment membrane materials under high-pressure conditions continue to increase. PES ultrafiltration membranes, with their excellent comprehensive performance and adaptability, have become the preferred core membrane material in the field of high-pressure reverse osmosis pretreatment, and their application scale continues to expand.

[0003] However, traditional polyethersulfone (PES) ultrafiltration membranes have significant performance limitations, restricting their long-term stable operation under complex high-pressure conditions. Firstly, the membrane's stability under high pressure is insufficient. The operating pressure in industrial high-pressure separation and high-pressure reverse osmosis pretreatment typically reaches 0.6 MPa, and in some harsh scenarios, it can reach 1.0–1.5 MPa. Traditional PES membranes have loosely packed molecular chains and lack rigid support in the pores, making them prone to irreversible deformation such as creep and pore structure compression and collapse under high pressure. This results in uneven pore size distribution, decreased sieving accuracy, rapid flux decline, and pollutant retention and leakage, not only reducing separation efficiency and deteriorating the quality of reverse osmosis feed water, but also making membrane modules difficult to reuse and increasing replacement frequency, significantly increasing industrial operating costs. Secondly, PES materials are inherently hydrophobic and have poor antifouling properties. Industrial wastewater and biopharmaceutical materials are rich in easily polluting substances such as proteins, colloids, microorganisms, and polysaccharides, which are easily adsorbed and deposited on the membrane surface and inside the pores through hydrophobic interactions, causing irreversible fouling. Membrane fouling directly reduces membrane flux, increases operating energy consumption, and affects separation stability. At the same time, frequent physical and chemical cleaning increases maintenance procedures and costs, and chemical reagent erosion and physical friction wear further shorten the service life of membrane modules, severely limiting the large-scale application of PES ultrafiltration membranes in various complex material separation scenarios.

[0004] To address the core defects of traditional PES ultrafiltration membranes, such as poor high-pressure stability and weak antifouling ability, existing modification methods mainly include three categories: inorganic filler blending, surface coating, and single hydrophilic monomer grafting. Although these methods can optimize the individual properties of the membrane to a certain extent, they cannot adapt to the harsh operating conditions of high-pressure reverse osmosis pretreatment and are difficult to achieve a synergistic improvement in "high pressure resistance, high antifouling ability, and high stability".

[0005] In summary, existing modification technologies are mostly single-dimensional optimizations with obvious limitations: inorganic blending focuses on enhancing structural strength but is difficult to improve antifouling properties, while surface coating and monomer grafting focus on improving antifouling performance but cannot solve the problem of high-pressure structural instability. They cannot achieve a synergistic improvement in mechanical stability and antifouling performance, which greatly limits the large-scale application of modified PES ultrafiltration membranes in high-pressure reverse osmosis pretreatment and industrial high-pressure separation.

[0006] Therefore, there is a need to develop a new pressure-resistant and dirt-resistant polyethersulfone ultrafiltration membrane based on in-situ crosslinking and its preparation method. Summary of the Invention

[0007] This application provides an in-situ crosslinked, pressure-resistant and dirt-resistant polyethersulfone ultrafiltration membrane and its preparation method, which is used to solve the above-mentioned technical problems.

[0008] This application provides a pressure-resistant and dirt-resistant polyethersulfone ultrafiltration membrane based on in-situ crosslinking. The ultrafiltration membrane includes: a host substrate, a three-dimensional semi-interpenetrating network located inside the host substrate, and zwitterionic hydrophilic monomers.

[0009] in,

[0010] The main substrate is polyethersulfone;

[0011] The three-dimensional semi-interpenetrating network is formed by in-situ crosslinking of terminal amino polyetheramine with hydrophilic epoxy monomer.

[0012] Furthermore, the terminal amino polyetheramine is at least one of difunctional polypropylene oxide-type terminal amino polyetheramine and trifunctional polypropylene oxide-type terminal amino polyetheramine.

[0013] Furthermore, the difunctional polypropylene oxide-terminated amino-terminated polyetheramine is one of D-230, D-400, D-2000 and D-4000, and the trifunctional polypropylene oxide-terminated amino-terminated polyetheramine is one of T-403, T-3000 and T-5000.

[0014] Furthermore, the hydrophilic epoxy monomer is at least one of polyethylene glycol diglycidyl ether and ethylene glycol diglycidyl ether.

[0015] Furthermore, the zwitterionic hydrophilic monomer is at least one of sulfonate betaine monomers and carboxylate betaine monomers.

[0016] Furthermore, the sulfonate betaine monomer is at least one of methacrylic acid sulfonate betaine, acrylamidopropyl sulfonate betaine, and vinylpyridinepropyl sulfonate betaine; the carboxylic acid betaine monomer is at least one of methacrylic acid carboxylic acid betaine and acrylamido carboxylic acid betaine.

[0017] Furthermore, the ultrafiltration membrane can withstand an operating pressure of ≥1.0 MPa, and after operating at 1.0 MPa for 12 h, the pure water flux decay rate is ≤10%, and the BSA flux recovery rate is ≥93%.

[0018] Furthermore, the ultrafiltration membrane is used for industrial high-pressure wastewater treatment and high-salinity wastewater pretreatment.

[0019] This application also provides a method for preparing a pressure-resistant and dirt-resistant polyethersulfone ultrafiltration membrane based on in-situ crosslinking, the method comprising the following steps:

[0020] Preparation and pre-reaction of casting solution: By weight, 16-20 parts of polyethersulfone, 4-10 parts of pore-forming agent, and 1.0-2.5 parts of zwitterionic hydrophilic monomer are dissolved in 62.7-76.7 parts of polar aprotic solvent and stirred at 40-60°C until completely dissolved to obtain the basic casting solution; 1.5-3.0 parts of amino-terminated polyetheramine and 0.8-1.8 parts of hydrophilic epoxy monomer are added to the basic casting solution, and the mixture is stirred at 40-60°C for 30-60 min for pre-reaction to obtain the pre-crosslinked casting solution;

[0021] Dry-wet phase inversion film formation: After vacuum degassing the pre-crosslinked casting liquid for 6-8 h, it is scraped onto a clean support substrate to form a uniform liquid film. The liquid film is evaporated in the air section for 20-45 s and then quickly immersed in a pure water coagulation bath at 20-30℃ for 30-45 min to form a phase inversion film, thus obtaining the primary film.

[0022] Post-curing crosslinking and purification: The nascent membrane is heat-treated in hot water at 40-55°C for 1-2 hours to complete the in-situ crosslinking reaction and form a three-dimensional semi-interpenetrating network; it is then soaked and washed with deionized water until neutral to obtain a pressure-resistant and dirt-resistant polyethersulfone ultrafiltration membrane based on in-situ crosslinking.

[0023] The pressure-resistant and fouling-resistant polyethersulfone ultrafiltration membrane based on in-situ crosslinking provided in this application constructs a rigid crosslinked network through the synergistic effect of terminal amino polyetheramines and epoxy monomers, significantly improving the structural stability and mechanical strength of the membrane and effectively avoiding structural deformation and performance degradation under high pressure. Compared with traditional polyethersulfone ultrafiltration membranes, the ultrafiltration membrane prepared in this application exhibits structural stability and no significant performance degradation under high pressure conditions, and possesses excellent antifouling capabilities, effectively reducing pollutant adsorption and deposition, preventing membrane pore blockage, ensuring separation accuracy and operational stability, and meeting the needs of industrial-scale production. It can be widely used in various complex separation and purification scenarios. Attached Figure Description

[0024] Figure 1 This is a scanning electron microscope image of the cross-section of the polyethersulfone ultrafiltration membrane of Example 1 of this application;

[0025] Figure 2 This is a scanning electron microscope (SEM) image of the cross-section of the polyethersulfone ultrafiltration membrane of Comparative Example 1 of this application. Detailed Implementation

[0026] To better understand the technical solution of the present invention, the following embodiments will further illustrate the method provided by the present invention. However, the present invention is not limited to the listed embodiments, but should also include any other well-known modifications within the scope of the claims of the present invention.

[0027] The present invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0028] Materials used in this invention: There are no special restrictions on the source of all raw materials in this invention and the following embodiments and comparative examples; they can be commercially available.

[0029] This application provides a pressure-resistant and dirt-resistant polyethersulfone ultrafiltration membrane based on in-situ crosslinking. The ultrafiltration membrane includes: a host substrate, a three-dimensional semi-interpenetrating network located inside the host substrate, and zwitterionic hydrophilic monomers.

[0030] in,

[0031] The main substrate is polyethersulfone;

[0032] The three-dimensional semi-interpenetrating network is formed by in-situ crosslinking of terminal amino polyetheramine with hydrophilic epoxy monomer.

[0033] In the embodiments described in this specification, the terminal amino polyetheramine is at least one of difunctional polypropylene oxide-type terminal amino polyetheramine and trifunctional polypropylene oxide-type terminal amino polyetheramine.

[0034] In the embodiments of this specification, the difunctional polypropylene oxide-terminated amino-terminated polyetheramine is one of D-230, D-400, D-2000 and D-4000, and the trifunctional polypropylene oxide-terminated amino-terminated polyetheramine is one of T-403, T-3000 and T-5000.

[0035] In the embodiments of this specification, the hydrophilic epoxy monomer is at least one of polyethylene glycol diglycidyl ether and ethylene glycol diglycidyl ether.

[0036] In the embodiments of this specification, the zwitterionic hydrophilic monomer is at least one of sulfonate betaine monomers and carboxylate betaine monomers.

[0037] In the embodiments of this specification, the sulfonate betaine monomer is at least one of methacrylic acid sulfonate betaine, acrylamidopropyl sulfonate betaine, and vinylpyridinepropyl sulfonate betaine; the carboxylic acid betaine monomer is at least one of methacrylic acid carboxylic acid betaine and acrylamido carboxylic acid betaine.

[0038] In the embodiments of this specification, the ultrafiltration membrane can withstand an operating pressure ≥1.0 MPa, and after operating at 1.0 MPa for 12 hours, the pure water flux decay rate is ≤10%, and the BSA flux recovery rate is ≥93%.

[0039] In the embodiments of this specification, the ultrafiltration membrane is used for industrial high-pressure wastewater treatment and high-salinity wastewater pretreatment.

[0040] This application also provides a method for preparing a pressure-resistant and dirt-resistant polyethersulfone ultrafiltration membrane based on in-situ crosslinking, the method comprising the following steps:

[0041] Preparation and pre-reaction of casting solution: By weight, 16-20 parts of polyethersulfone, 4-10 parts of pore-forming agent, and 1.0-2.5 parts of zwitterionic hydrophilic monomer are dissolved in 62.7-76.7 parts of polar aprotic solvent and stirred at 40-60°C until completely dissolved to obtain the basic casting solution; 1.5-3.0 parts of amino-terminated polyetheramine and 0.8-1.8 parts of hydrophilic epoxy monomer are added to the basic casting solution, and the mixture is stirred at 40-60°C for 30-60 min for pre-reaction to obtain the pre-crosslinked casting solution;

[0042] Dry-wet phase inversion film formation: After vacuum degassing the pre-crosslinked casting liquid for 6-8 h, it is scraped onto a clean support substrate to form a uniform liquid film. The liquid film is evaporated in the air section for 20-45 s and then quickly immersed in a pure water coagulation bath at 20-30℃ for 30-45 min to form a phase inversion film, thus obtaining the primary film.

[0043] Post-curing crosslinking and purification: The nascent membrane is heat-treated in hot water at 40-55°C for 1-2 hours to complete the in-situ crosslinking reaction and form a three-dimensional semi-interpenetrating network; it is then soaked and washed with deionized water until neutral to obtain a pressure-resistant and dirt-resistant polyethersulfone ultrafiltration membrane based on in-situ crosslinking.

[0044] In the embodiments of this specification, the polar aprotic solvent is: N,N-dimethylacetamide or N-methylpyrrolidone.

[0045] To further illustrate the present invention, the preparation method of the pressure-resistant and dirt-resistant polyethersulfone ultrafiltration membrane based on in-situ crosslinking provided by the present invention will be described in detail below with reference to the embodiments, but these should not be construed as limiting the scope of protection of the present invention.

[0046] Example 1

[0047] The method for preparing the pressure-resistant and dirt-resistant polyethersulfone ultrafiltration membrane based on in-situ crosslinking in this embodiment includes the following methods:

[0048] (1) Preparation and pre-reaction of casting solution: Weigh 18 g polyethersulfone, 5 g pore-forming agent PEG2000 (polyethylene glycol 2000) and 1.5 g SBMA (methacrylic acid sulfonate betaine), add them to 72.3 g DMAC (N,N-dimethylacetamide), place them in a 50℃ constant temperature oil bath, and stir at a constant speed until polyethersulfone and PEG2000 are completely dissolved to obtain a uniform and transparent basic casting solution; then add 1.0 g T-403, 1.0 g D-230 and 1.2 g PEGDE (polyethylene glycol diglycidyl ether) 200 in sequence, keep the temperature at 50℃ and stir for 45 min to carry out a pre-crosslinking reaction, so that T-403, D-230 and PEGDE200 undergo a preliminary ring-opening addition reaction to form a pre-crosslinking system.

[0049] (2) Degassing and film scraping of casting solution: The casting solution after the above pre-reaction was restored to room temperature and vacuum degassed for 6-8 h; using glass as the supporting substrate, a flat plate film scraping machine was used, the thickness of the scraper was adjusted to 250 μm, and a uniform liquid film was scraped at a uniform speed. After the film scraping was completed, the glass substrate was placed in the air (temperature 25℃, humidity 40%~60%) for 30 s to allow the solvent on the film surface to evaporate initially and form a preliminary film structure.

[0050] (3) Phase transformation to form a membrane: The glass substrate that has completed the air section evaporation is quickly immersed in a pure water coagulation bath at 25°C, kept at a constant temperature and left to stand, and a dry-wet phase transformation reaction is carried out for 30~45 min to form a primary ultrafiltration membrane with an asymmetric structure.

[0051] (4) Post-curing crosslinking and purification: The nascent membrane formed in the coagulation bath is peeled off from the glass substrate and transferred to a constant temperature water bath at 45°C for heat treatment for 1.5 h to allow the crosslinking reaction of T-403, D-230 and PEGDE200 to proceed completely and form a stable three-dimensional interpenetrating network structure. After the heat treatment, the membrane is repeatedly soaked and washed in pure water until the washing solution is neutral to remove unreacted monomers, solvents and impurities from the membrane surface and membrane pores, thus obtaining a pressure-resistant and dirt-resistant polyethersulfone ultrafiltration membrane based on in-situ crosslinking.

[0052] The prepared in-situ crosslinked, pressure-resistant, and fouling-resistant polyethersulfone ultrafiltration membrane was subjected to tensile strength, pure water flux stability, and fouling resistance tests. The tensile strength test conditions were as follows: the gauge length of the specimen was set to 100 mm, and the beam tensile speed was set to... The results of the room temperature test are shown in Table 1.

[0053] Hydrophilicity test: The hydrophilicity of the ultrafiltration membrane surface was tested using static contact angle, and the results are shown in Table 1.

[0054] Tensile strength test at break: The tensile strength and elongation at break of the membrane were tested using an electronic universal testing machine. The results are shown in Table 1.

[0055] Pure water flux stability test: The cross-flow diaphragm test station was used for testing. The operating pressure was 1.0 MPa, the temperature was 25℃, and the operation time was 12 h. The initial 0 h flux and 12 h flux results are shown in Table 1.

[0056] Fouling resistance test: The cross-flow membrane test station was used for testing. First, pure water was used for testing for 30 minutes to obtain the initial stable flux. Then, under the test conditions of 500 ppm BSA aqueous solution, 1.0 MPa operating pressure, 25℃ temperature and pH value of 6.5 to 7.5, the system was run for 8 hours. After rinsing with pure water for 10 minutes, the stable flux of pure water was tested. The results are shown in Table 1.

[0057] Example 2

[0058] A method for preparing a pressure-resistant and dirt-resistant polyethersulfone ultrafiltration membrane based on in-situ crosslinking includes the following steps:

[0059] (1) Preparation and pre-reaction of casting solution: Weigh 18 g polyethersulfone, 5 g pore-forming agent PEG2000 and 1.5 g SBMA, add them to 72.3 g DMAC, place them in a 50℃ constant temperature oil bath, and stir at a constant speed until polyethersulfone and PEG2000 are completely dissolved to obtain a uniform and transparent basic casting solution; then add 2.0 g T-403 and 1.2 g PEGDE200 in sequence, keep the temperature at 50℃ and stir for 45 min to carry out a pre-crosslinking reaction, so that T-403 and PEGDE200 undergo a preliminary ring-opening addition reaction to form a pre-crosslinking system.

[0060] (2) Degassing and film scraping of casting solution: The casting solution after the above pre-reaction was restored to room temperature and vacuum degassed for 6-8 h; using glass as the supporting substrate, a flat plate film scraping machine was used, the thickness of the scraper was adjusted to 250 μm, and a uniform liquid film was scraped at a uniform speed. After the film scraping was completed, the glass substrate was placed in the air (temperature 25℃, humidity 40%~60%) for 30 s to allow the solvent on the film surface to evaporate initially and form a preliminary film structure.

[0061] (3) Phase transformation to form a membrane: The glass substrate that has completed the air section evaporation is quickly immersed in a pure water coagulation bath at 25°C, kept at a constant temperature and left to stand, and a dry-wet phase transformation reaction is carried out for 30~45 min to form a primary ultrafiltration membrane with an asymmetric structure.

[0062] (4) Post-curing crosslinking and purification: The nascent membrane formed in the coagulation bath is peeled off from the glass substrate and transferred to a constant temperature water bath at 45°C for heat treatment for 1.5 h to allow the crosslinking reaction between T-403 and PEGDE200 to proceed completely and form a stable three-dimensional interpenetrating network structure. After the heat treatment, the membrane is repeatedly immersed and washed in pure water until the washing solution is neutral to remove unreacted monomers, solvents and impurities from the membrane surface and membrane pores, thus obtaining a pressure-resistant and dirt-resistant polyethersulfone ultrafiltration membrane based on in-situ crosslinking.

[0063] The ultrafiltration membrane was tested using the same method as in Example 1, and the test results are shown in Table 1.

[0064] Example 3

[0065] A method for preparing a pressure-resistant and dirt-resistant polyethersulfone ultrafiltration membrane based on in-situ crosslinking includes the following steps:

[0066] (1) Preparation and pre-reaction of casting solution: Weigh 18 g polyethersulfone, 5.3 g pore-forming agent PEG2000 and 1.5 g SBMA, add them to 72.3 g DMAC, place them in a 50℃ constant temperature oil bath, and stir at a constant speed until polyethersulfone and PEG2000 are completely dissolved to obtain a uniform and transparent basic casting solution; then add 2 g D-230 and 1.2 g PEGDE200 in sequence, keep the temperature at 50℃ and stir for 45 min to carry out a pre-crosslinking reaction, so that D-230 and PEGDE200 undergo a preliminary ring-opening addition reaction to form a pre-crosslinking system.

[0067] (2) Degassing and film scraping of casting solution: The casting solution after the above pre-reaction was restored to room temperature and vacuum degassed for 6-8 h; a clean glass substrate was used as the support substrate, and a flat plate film scraper was used to adjust the thickness of the scraper to 250 μm and scrape at a uniform speed to form a uniform liquid film. After the film scraping was completed, the glass substrate was placed in the air (temperature 25℃, humidity 40%~60%) for 30 s to allow the solvent on the film surface to evaporate initially and form a preliminary film structure.

[0068] (3) Phase transformation to form a membrane: The glass substrate that has completed the air section evaporation is quickly immersed in a pure water coagulation bath at 25°C, kept at a constant temperature and left to stand, and a dry-wet phase transformation reaction is carried out for 30~45 min to form a primary ultrafiltration membrane with an asymmetric structure.

[0069] (4) Post-curing crosslinking and purification: The nascent membrane formed in the coagulation bath is peeled off from the glass substrate and transferred to a constant temperature water bath at 45°C for heat treatment for 1.5 h to allow the crosslinking reaction between D-230 and PEGDE200 to proceed completely and form a stable three-dimensional interpenetrating network structure. After the heat treatment, the membrane is repeatedly immersed and washed in pure water until the washing solution is neutral to remove unreacted monomers, solvents and impurities from the membrane surface and membrane pores, thus obtaining a pressure-resistant and dirt-resistant polyethersulfone ultrafiltration membrane based on in-situ crosslinking.

[0070] The ultrafiltration membrane was tested using the same method as in Example 1, and the test results are shown in Table 1.

[0071] Example 4

[0072] A method for preparing a pressure-resistant and dirt-resistant polyethersulfone ultrafiltration membrane based on in-situ crosslinking includes the following steps:

[0073] (1) Preparation and pre-reaction of casting solution: Weigh 18 g polyethersulfone, 5 g pore-forming agent PEG2000 and 1.5 g CBAA (acrylamidocarboxylic acid betaine), add them to 72.3 g DMAC, place them in a 50℃ constant temperature oil bath, and stir at a constant speed until polyethersulfone and PEG2000 are completely dissolved to obtain a uniform and transparent basic casting solution; then add 1.0 g T-403, 1.0 g D-230 and 1.2 g PEGDE1000 in sequence, keep the temperature at 50℃ and stir for 45 min to carry out a pre-crosslinking reaction, so that T-403, D-230 and PEGDE1000 undergo a preliminary ring-opening addition reaction to form a pre-crosslinking system.

[0074] (2) Degassing and film scraping of casting solution: The casting solution after the above pre-reaction was restored to room temperature and vacuum degassed for 6-8 h; using glass as the supporting substrate, a flat plate film scraping machine was used, the thickness of the scraper was adjusted to 250 μm, and a uniform liquid film was scraped at a uniform speed. After the film scraping was completed, the glass substrate was placed in the air (temperature 25℃, humidity 40%~60%) for 30 s to allow the solvent on the film surface to evaporate initially and form a preliminary film structure.

[0075] (3) Phase transformation to form a membrane: The glass substrate that has completed the air section evaporation is quickly immersed in a pure water coagulation bath at 25°C, kept at a constant temperature and left to stand, and a dry-wet phase transformation reaction is carried out for 30~45 min to form a primary ultrafiltration membrane with an asymmetric structure.

[0076] (4) Post-curing crosslinking and purification: The nascent membrane formed in the coagulation bath is peeled off from the glass substrate and transferred to a constant temperature water bath at 45°C for heat treatment for 1.5 h to allow the crosslinking reaction of T-403, D-230 and PEGDE1000 to proceed completely and form a stable three-dimensional interpenetrating network structure. After the heat treatment, the membrane is repeatedly immersed and washed in pure water until the washing solution is neutral to remove unreacted monomers, solvents and impurities from the membrane surface and membrane pores, thus obtaining a pressure-resistant and dirt-resistant polyethersulfone ultrafiltration membrane based on in-situ crosslinking.

[0077] The ultrafiltration membrane was tested using the same method as in Example 1, and the test results are shown in Table 1.

[0078] Example 5

[0079] A method for preparing a pressure-resistant and dirt-resistant polyethersulfone ultrafiltration membrane based on in-situ crosslinking includes the following steps:

[0080] (1) Preparation and pre-reaction of casting solution: Weigh 18 g polyethersulfone, 5 g pore-forming agent PEG2000 and 2.0 g AMPPS (acrylamidopropyl betaine), add them to 71.8 g NMP (N-methylpyrrolidone), place them in a 50℃ constant temperature oil bath, and stir at a constant speed until polyethersulfone and PEG2000 are completely dissolved to obtain a uniform and transparent basic casting solution; then add 1.0 g T-403, 1.0 g D-230 and 1.2 g PEGDE1000 in sequence, keep the temperature at 50℃ and stir for 45 min to carry out a pre-crosslinking reaction, so that T-403, D-230 and PEGDE1000 undergo a preliminary ring-opening addition reaction to form a pre-crosslinking system.

[0081] (2) Degassing and film scraping of casting solution: The casting solution after the above pre-reaction was restored to room temperature and vacuum degassed for 6-8 h; using glass as the supporting substrate, a flat plate film scraping machine was used, the thickness of the scraper was adjusted to 250 μm, and a uniform liquid film was scraped at a uniform speed. After the film scraping was completed, the glass substrate was placed in the air (temperature 25℃, humidity 40%~60%) for 30 s to allow the solvent on the film surface to evaporate initially and form a preliminary film structure.

[0082] (3) Phase transformation to form a membrane: The glass substrate that has completed the air section evaporation is quickly immersed in a pure water coagulation bath at 25°C, kept at a constant temperature and left to stand, and a dry-wet phase transformation reaction is carried out for 30~45 min to form a primary ultrafiltration membrane with an asymmetric structure.

[0083] (4) Post-curing crosslinking and purification: The nascent membrane formed in the coagulation bath is peeled off from the glass substrate and transferred to a constant temperature water bath at 45°C for heat treatment for 1.5 h to allow the crosslinking reaction of T-403, D-230 and PEGDE1000 to proceed completely and form a stable three-dimensional interpenetrating network structure. After the heat treatment, the membrane is repeatedly immersed and washed in pure water until the washing solution is neutral to remove unreacted monomers, solvents and impurities from the membrane surface and membrane pores, thus obtaining a pressure-resistant and dirt-resistant polyethersulfone ultrafiltration membrane based on in-situ crosslinking.

[0084] The ultrafiltration membrane was tested using the same method as in Example 1, and the test results are shown in Table 1.

[0085] Comparative Example 1

[0086] A method for preparing a polyethersulfone ultrafiltration membrane includes the following steps:

[0087] (1) Preparation of casting solution: Weigh 18 g of polyethersulfone and 5 g of pore-forming agent PEG2000, add them to 77 g of DMAC, place them in a 50℃ constant temperature oil bath, and stir at a constant speed until the polyethersulfone and PEG2000 are completely dissolved to obtain a uniform and transparent basic casting solution.

[0088] (2) Degassing and film scraping of casting solution: The casting solution was restored to room temperature and vacuum degassed for 6-8 h. Using glass as the supporting substrate, a flat plate film scraping machine was used to adjust the thickness of the scraper to 250 μm and scrape at a uniform speed to form a uniform liquid film. After the film scraping was completed, the glass substrate was placed in the air (temperature 25℃, humidity 40%-60%) for 30 s to allow the solvent on the film surface to evaporate initially and form a preliminary film structure.

[0089] (3) Phase transformation to form a membrane: The glass substrate that has completed the air section evaporation is quickly immersed in a pure water coagulation bath at 25°C, kept at a constant temperature and left to stand, and a dry-wet phase transformation reaction is carried out for 30~45 min to form a primary ultrafiltration membrane with an asymmetric structure.

[0090] (4) Post-treatment: The nascent membrane formed in the coagulation bath is peeled off from the glass substrate and transferred to a constant temperature water bath at 45°C. After heat treatment for 1.5 h, the membrane is repeatedly soaked and washed in pure water to remove solvent and impurities from the membrane surface and membrane pores, thus obtaining a polyethersulfone ultrafiltration membrane.

[0091] The ultrafiltration membrane was tested using the same method as in Example 1, and the test results are shown in Table 1.

[0092] Comparative Example 2

[0093] A method for preparing a pressure-resistant polyethersulfone ultrafiltration membrane includes the following steps:

[0094] (1) Preparation and pre-reaction of casting solution: Weigh 18 g of polyethersulfone and 5 g of pore-forming agent PEG2000, add them to 73.8 g of DMAC, place them in a 50℃ constant temperature oil bath, and stir at a constant speed until polyethersulfone and PEG2000 are completely dissolved to obtain a uniform and transparent basic casting solution; then add 1.0 g of T-403, 1.0 g of D-230 and 1.2 g of PEGDE 200 in sequence, keep the temperature at 50℃ and stir for 45 min to carry out a pre-crosslinking reaction, so that T-403, D-230 and PEGDE200 undergo a preliminary ring-opening addition reaction to form a pre-crosslinking system.

[0095] (2) Degassing and film scraping of casting solution: The casting solution after the above pre-reaction was restored to room temperature and vacuum degassed for 6-8 h; using glass as the supporting substrate, a flat plate film scraping machine was used, the thickness of the scraper was adjusted to 250 μm, and a uniform liquid film was scraped at a uniform speed. After the film scraping was completed, the glass substrate was placed in the air (temperature 25℃, humidity 40%~60%) for 30 s to allow the solvent on the film surface to evaporate initially and form a preliminary film structure.

[0096] (3) Phase transformation to form a membrane: The glass substrate that has completed the air section evaporation is quickly immersed in a pure water coagulation bath at 25°C, kept at a constant temperature and left to stand, and a dry-wet phase transformation reaction is carried out for 30~45 min to form a primary ultrafiltration membrane with an asymmetric structure.

[0097] (4) Post-curing crosslinking and purification: The nascent membrane formed in the coagulation bath is peeled off from the glass substrate and transferred to a constant temperature water bath at 45°C for heat treatment for 1.5 h to allow the crosslinking reaction of T-403, D-230 and PEGDE200 to proceed completely and form a stable three-dimensional interpenetrating network structure. After the heat treatment, the membrane is repeatedly soaked and washed in pure water until the washing solution is neutral to remove unreacted monomers, solvents and impurities from the membrane surface and membrane pores, thus obtaining a pressure-resistant and dirt-resistant polyethersulfone ultrafiltration membrane based on in-situ crosslinking.

[0098] The ultrafiltration membrane was tested using the same method as in Example 1, and the test results are shown in Table 1.

[0099] Comparative Example 3

[0100] A method for preparing an antifouling polyethersulfone ultrafiltration membrane includes the following steps:

[0101] (1) Preparation and pre-reaction of casting solution: Weigh 18 g polyethersulfone, 5 g pore-forming agent PEG2000 and 1.5 g SBMA, add them to 75.5 g DMAC, place them in a constant temperature oil bath at 50℃, and stir at a constant speed until polyethersulfone and PEG2000 are completely dissolved to obtain a uniform and transparent basic casting solution.

[0102] (2) Degassing and film scraping of casting solution: The casting solution after the above pre-reaction was restored to room temperature and vacuum degassed for 6-8 h; using glass as the supporting substrate, a flat plate film scraping machine was used, the thickness of the scraper was adjusted to 250 μm, and a uniform liquid film was scraped at a uniform speed. After the film scraping was completed, the glass substrate was placed in the air (temperature 25℃, humidity 40%~60%) for 30 s to allow the solvent on the film surface to evaporate initially and form a preliminary film structure.

[0103] (3) Phase transformation to form a membrane: The glass substrate that has completed the air section evaporation is quickly immersed in a pure water coagulation bath at 25°C, kept at a constant temperature and left to stand, and a dry-wet phase transformation reaction is carried out for 30~45 min to form a primary ultrafiltration membrane with an asymmetric structure.

[0104] (4) Post-treatment: The nascent membrane formed in the coagulation bath is peeled off from the glass substrate and transferred to a constant temperature water bath at 45°C. After heat treatment for 1.5 h, the membrane is repeatedly soaked and washed in pure water until the washing solution is neutral to remove unreacted monomers, solvents and impurities from the membrane surface and membrane pores, thus obtaining a dirt-resistant polyethersulfone ultrafiltration membrane.

[0105] The ultrafiltration membrane was tested using the same method as in Example 1, and the test results are shown in Table 1.

[0106] Table 1

[0107]

[0108] The data in the table above show that the addition of terminal amino polyetheramine, hydrophilic epoxy monomer, and zwitterionic hydrophilic monomer significantly improves the tensile strength and elongation at break of the membrane, while reducing the pure water contact angle. In the examples, the ultrafiltration membrane exhibited a much higher pure water flux recovery rate after 8 hours of enhanced fouling with BSA solution (bovine serum albumin) compared to the membrane in the comparative example. These results indicate that the compressive strength and fouling resistance of the in-situ crosslinked, pressure-resistant, and fouling-resistant polyethersulfone ultrafiltration membrane described in this invention are significantly superior to the original ultrafiltration membrane after in-situ crosslinking and the introduction of zwitterionic hydrophilic monomers.

[0109] The pressure-resistant and fouling-resistant polyethersulfone ultrafiltration membrane based on in-situ crosslinking provided in this application constructs a rigid crosslinked network through the synergistic effect of terminal amino polyetheramines and epoxy monomers, significantly improving the structural stability and mechanical strength of the membrane and effectively avoiding structural deformation and performance degradation under high pressure. Compared with traditional polyethersulfone ultrafiltration membranes, the ultrafiltration membrane prepared in this application exhibits structural stability and no significant performance degradation under high pressure conditions, and possesses excellent antifouling capabilities, effectively reducing pollutant adsorption and deposition, preventing membrane pore blockage, ensuring separation accuracy and operational stability, and meeting the needs of industrial-scale production. It can be widely used in various complex separation and purification scenarios.

[0110] The above description is merely a preferred embodiment of the present invention and is not intended to limit the implementation. It should be noted that those skilled in the art can make other variations or modifications without departing from the principles of the present invention, and any obvious variations or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A pressure-resistant and dirt-resistant polyethersulfone ultrafiltration membrane based on in-situ crosslinking, characterized in that, The ultrafiltration membrane comprises: a host substrate, a three-dimensional semi-interpenetrating network located inside the host substrate, and zwitterionic hydrophilic monomers; in, The main substrate is polyethersulfone; The three-dimensional semi-interpenetrating network is formed by in-situ crosslinking of terminal amino polyetheramine with hydrophilic epoxy monomer; The zwitterionic hydrophilic monomer is at least one of sulfonate betaine monomers and carboxylate betaine monomers, wherein the sulfonate betaine monomer is at least one of methacrylic acid sulfonate betaine, acrylamidopropyl sulfonate betaine, and vinylpyridinylpropyl sulfonate betaine; and the carboxylate betaine monomer is at least one of methacrylic acid carboxylate betaine and acrylamido carboxylate betaine.

2. The ultrafiltration membrane as described in claim 1, characterized in that, The terminal amino polyetheramine is at least one of difunctional polypropylene oxide-type terminal amino polyetheramine and trifunctional polypropylene oxide-type terminal amino polyetheramine.

3. The ultrafiltration membrane as described in claim 2, characterized in that, The difunctional polypropylene oxide-terminated amino-terminated polyetheramine is one of D-230, D-400, D-2000 and D-4000, and the trifunctional polypropylene oxide-terminated amino-terminated polyetheramine is one of T-403, T-3000 and T-5000.

4. The ultrafiltration membrane as described in claim 1, characterized in that, The hydrophilic epoxy monomer is at least one of polyethylene glycol diglycidyl ether and ethylene glycol diglycidyl ether.

5. The ultrafiltration membrane as described in claim 1, characterized in that, The ultrafiltration membrane can withstand an operating pressure of ≥1.0 MPa. When operating at 1.0 MPa for 12 hours, the pure water flux decay rate is ≤10%, and the BSA flux recovery rate is ≥93%.

6. The ultrafiltration membrane as described in claim 1, characterized in that, The ultrafiltration membrane is used for industrial high-pressure wastewater treatment and high-salt wastewater pretreatment.

7. A method for preparing a pressure-resistant and dirt-resistant polyethersulfone ultrafiltration membrane based on in-situ crosslinking as described in any one of claims 1-6, characterized in that, The preparation method includes the following steps: Preparation and pre-reaction of casting solution: By weight, 16-20 parts of polyethersulfone, 4-10 parts of pore-forming agent, and 1.0-2.5 parts of zwitterionic hydrophilic monomer are dissolved in 65-72 parts of polar aprotic solvent and stirred at 40-60°C until completely dissolved to obtain the basic casting solution; 1.5-3.0 parts of amino-terminated polyetheramine and 0.8-1.8 parts of hydrophilic epoxy monomer are added to the basic casting solution, and the mixture is stirred at 40-60°C for 30-60 min for pre-reaction to obtain the pre-crosslinked casting solution; Dry-wet phase inversion film formation: After vacuum degassing the pre-crosslinked casting liquid for 6-8 h, it is scraped onto a clean support substrate to form a uniform liquid film. The liquid film is evaporated in the air section for 20-45 s and then quickly immersed in a pure water coagulation bath at 20-30℃ for 30-45 min to form a phase inversion film, thus obtaining the primary film. Post-curing crosslinking and purification: The nascent membrane is heat-treated in hot water at 40-55°C for 1-2 hours to complete the in-situ crosslinking reaction and form a three-dimensional semi-interpenetrating network; it is then soaked and washed with deionized water until neutral to obtain a pressure-resistant and dirt-resistant polyethersulfone ultrafiltration membrane based on in-situ crosslinking.

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