PES composite ultrafiltration membrane based on MXene material modification and preparation method thereof

Abstract

This invention belongs to the field of polymer materials technology, specifically relating to a PES composite ultrafiltration membrane modified with MXene material and its preparation method. The preparation method includes the following steps: (1) Weighing raw materials according to the following mass percentages: 16-20% modified PES powder, 0.08-0.13% SnO2, 0.01-0.03% MXene, 0.8-1.5% PVP, and the balance being DMAc; (2) Dispersing SnO2, MXene, and PVP in DMAc, and then subjecting them to ultrasonic treatment for 1-3 hours to obtain a mixture; (3) Preparing a casting solution; (4) Defoaming the casting solution, uniformly coating the casting solution onto a glass plate at room temperature, and then placing the glass plate in a deionized water condensation bath to obtain a PES composite ultrafiltration membrane modified with MXene material. The ultrafiltration membrane prepared by this invention has excellent anti-protein contamination performance.

Description

Technical Field

[0001] This invention belongs to the field of organic polymer materials technology, specifically relating to a PES composite ultrafiltration membrane based on MXene material modification and its preparation method. Background Technology

[0002] Membrane separation technology refers to the technique of separating a mixture of molecules with different particle sizes using a membrane in water treatment. It involves no phase change and produces no secondary pollution, making it of significant practical importance in water resource recycling. Ultrafiltration (UF) is one of the most popular wastewater treatment technologies among membrane technologies because of its potential advantages in separating macromolecules, bacteria, heavy metals, dyes, and specific compounds. However, in the process of treating polluted water sources, the deposition of contaminants on the membrane leads to severe membrane fouling, which affects membrane permeability and selectivity, shortens membrane life, and increases maintenance costs and design complexity. Therefore, how to prevent or mitigate membrane fouling has always been a key focus of research and industrial applications.

[0003] Polyethersulfone (PES) membranes are high-performance polymer membrane materials widely used in wastewater treatment, seawater desalination, food processing, and biomedicine. While PES exhibits good chemical stability, it has relatively low hydrophilicity compared to many other membrane materials and possesses strong hydrophobicity and pore size inhomogeneity. During membrane fabrication, it easily adsorbs hydrophobic substances such as colloids and proteins, leading to membrane fouling. Membrane fouling causes a series of problems, including decreased membrane flux, shortened lifespan, and increased production costs, hindering the practical application of PES ultrafiltration membranes in wastewater treatment and the further promotion and application of ultrafiltration technology.

[0004] Polyethersulfone (PES) polymers are widely used in the manufacture of ultrafiltration membranes due to their excellent acid and alkali resistance, physicochemical resistance, film-forming properties, and thermal stability. However, current PES ultrafiltration membrane preparation processes suffer from difficulties in controlling the membrane structure and low reproducibility of the preparation results. Furthermore, due to its strong hydrophobicity and pore size inhomogeneity, PES easily adsorbs hydrophobic substances such as colloids and proteins during membrane fabrication, which can easily lead to membrane fouling. Membrane fouling limits the service life, flux, and production cost of PES ultrafiltration membranes, hindering the application and development of ultrafiltration technology.

[0005] Therefore, there is an urgent need for a PES composite ultrafiltration membrane based on MXene material modification and its preparation method. Summary of the Invention

[0006] The purpose of this invention is to provide a PES composite ultrafiltration membrane based on MXene material modification and its preparation method.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] This invention provides a method for preparing a PES composite ultrafiltration membrane based on MXene material modification, comprising the following steps:

[0009] (1) Weigh the raw materials according to the following mass percentages: 16-20% modified PES powder, 0.08-0.13% SnO2, 0.01-0.03% MXene, 0.8-1.5% PVP and the balance being DMAc;

[0010] (2) Disperse SnO2, MXene and PVP in DMAc, and then sonicate for 1-3 hours to obtain a mixture;

[0011] (3) Add the modified PES powder to the mixture and stir at 60-90℃ for 4-8 hours until the PES powder is completely dissolved to obtain the casting liquid;

[0012] (4) Defoaming the casting solution: At room temperature, use a casting blade (200μm) to evenly coat the casting solution onto a smooth glass plate. Then, slowly place the glass plate into a deionized water condensation bath. As the phase change is completed, the membrane automatically separates from the glass plate. Keep the membrane in deionized water for 12-24 hours to fully remove excess solvent and obtain a PES composite ultrafiltration membrane modified with MXene material.

[0013] Furthermore, SnO2 comprises tin oxide A, tin oxide B, and tin oxide C in a mass ratio of 1:(1.2-1.5):(0.4-0.7); the average particle size of tin oxide A is 20-50 nm, and the specific surface area is 75-98 m². 2 / g; the average particle size of tin oxide B is 150-200nm, and the specific surface area is 34-51m². 2 / g; the average particle size of tin oxide B is 300-400nm, and the specific surface area is 9-16m². 2 / g; all ordered from Beijing Juguang Wintech Technology Co., Ltd.

[0014] This invention introduces two-dimensional transition metal carbides / nitrides (MXenes) into a polymer ultrafiltration membrane mixed with tin oxide. The two components work synergistically, improving both the antifouling and separation capabilities of the composite membrane. By adding a specific ratio of compounded tin oxide, this invention improves the flux and rejection rate of BSA solutions in PES composite ultrafiltration membranes modified with MXene materials. This is primarily because the different particle sizes of SnO2 particles after compounding allow for a more uniform and rational pore structure within the membrane, thereby increasing the rejection rate. Simultaneously, it increases the mechanical strength and stability of the membrane, making it less prone to deformation or breakage during filtration. This not only helps maintain the physical integrity of the membrane but also ensures stable performance under high-pressure operating conditions. Different SnO2 particle sizes and surface areas affect the hydrophilicity and charge properties of the membrane surface; appropriately adjusting these parameters can make the membrane surface more hydrophilic, reducing the adsorption of biomolecules such as proteins, lowering the risk of membrane fouling, and thus maintaining a high flux.

[0015] Furthermore, MXene is a Ti3C2Tx wafer with 1-5 layers and a radial dimension of 0.5-2 μm.

[0016] Furthermore, the viscosity-average molecular weight of PVP is 3000-7000. Purchased from Boai New Open Source Medical Technology Group Co., Ltd.

[0017] Furthermore, the preparation method of modified PES powder includes the following steps:

[0018] (1) Hydroquinone, 2,5-dihydroxyterephthalic acid, 4,4'-dichlorodiphenyl sulfone, dimethyl sulfoxide, toluene and anhydrous potassium carbonate are mixed and heated to 150-155℃ under nitrogen protection and stirring. After reacting at this temperature for 4-6 hours, the temperature is raised to 168-170℃ and the reaction continues for another 4-6 hours to obtain the polymer product. The polymer product is cooled and solidified, pulverized, washed 2-3 times with boiling deionized water, and then refluxed with 36-38wt% hydrochloric acid for 25-30 hours. After filtration, it is washed with deionized water, dried, and pulverized to a particle size of less than 9μm to obtain carboxylated modified polyethersulfone powder.

[0019] (2) Mix 3-isocyanate-propyltrimethoxysilane (CAS: 15396-00-6, purchased from Shanghai Ruichu Biotechnology Co., Ltd.) and carboxylated modified polyethersulfone powder, and sonicate for 20-30 min; then add toluene, heat to 105-100℃ and stir for 2-3 h, recover toluene by vacuum distillation, wash the solid product with ethanol 2-3 times, and freeze dry to obtain silane-modified polyethersulfone powder;

[0020] (3) Add 0.03 parts by weight of silane-modified polyethersulfone powder to 30-35 parts by weight of ethanol and sonicate for 20-30 min to prepare an alcohol solution; weigh 0.03 parts by weight of nano TiO2 and add it to 25-30 parts by weight of deionized water, sonicate for 20-30 min to prepare a TiO2 aqueous solution;

[0021] (4) Under stirring conditions, TiO2 aqueous solution is added dropwise to alcohol solution, heated to 60-65℃, stirred for 2-4 hours, centrifuged to remove supernatant, washed 3-4 times with deionized water, and freeze-dried to obtain modified PES powder.

[0022] Furthermore, the mass of hydroquinone, sodium 3-(4-(-2,6'-difluorophenylcarbonyl)phenyl)propanesulfonate, 4,4'-difluorodiphenyl sulfone, dimethyl sulfoxide, toluene and anhydrous potassium carbonate is (6-8):(13-15):(43-45):(290-300):120:(72-75).

[0023] Furthermore, the mass ratio of 3-isocyanate-propyltrimethoxysilane, carboxylated modified polyethersulfone powder, and toluene is (1-1.2):0.1:(60-70).

[0024] Furthermore, the mass ratio of silane-modified polyethersulfone powder to nano-TiO2 is 10:(1-3).

[0025] Furthermore, the nano-TiO2 includes nano-TiO2Ⅰ, nano-TiO2Ⅱ, and nano-TiO2Ⅲ with a mass ratio of (1.3-1.5):1:(0.5-0.7); the average primary particle size of TiO2Ⅰ is 15 nm, and the specific surface area is 30-100 m². 2 / g (model DK405); Nano TiO2Ⅱ has an average primary particle size of 60nm and a specific surface area of ​​20-60m². 2 The average primary particle size of / g(DK405-2) and nano-TiO2Ⅲ is 200nm, and the specific surface area is 15m². 2 / g(DK405-3). Purchased from Beijing Deco Island Gold Technology Co., Ltd.

[0026] Commercially available PES powder is highly hydrophobic, making it prone to adsorbing hydrophobic substances such as colloids and proteins during membrane fabrication, which can easily lead to membrane fouling. This invention addresses this by preparing modified PES powder and grafting carboxyl groups and titanium dioxide onto it. This facilitates the binding of more water molecules through hydrogen bonding. The nano-sized TiO2 particles provide more surface hydroxyl sites, which can form stronger interactions with water molecules, further enhancing the material's hydrophilicity and thus increasing its fouling resistance. Simultaneously, it also improves the long-term stability of MXene-modified PES composite ultrafiltration membranes.

[0027] The second aspect of the present invention provides a PES composite ultrafiltration membrane based on MXene material modification prepared by the preparation method described above.

[0028] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows:

[0029] 1. To address the aforementioned issues, photocatalytic materials can be combined with traditional polymer membranes. Utilizing the ability of photocatalytic materials to effectively degrade dye pollutants under light irradiation, the active antifouling capability of PES-based ultrafiltration membranes can be significantly improved, potentially providing a valuable solution for wastewater treatment applications. MXenes are a class of two-dimensional inorganic compounds in materials science. These materials consist of transition metal carbides, nitrides, or carbonitrides with a thickness of several atomic layers. In this study, two-dimensional transition metal carbides / nitrides (MXenes) with photocatalytic properties were loaded onto PES membranes via blending and phase inversion methods to prepare MXene / SnO2 / PES composite membranes with excellent anti-protein fouling properties.

[0030] 2. This invention prepares PES membranes with different SnO2 / MXene contents via a blend-phase inversion method. The unique surface function of MXene provides a broad platform for SnO2 nanoparticles, offering numerous active sites for loading them, thereby generating a large number of photogenerated electrons and improving the photodegradation effect of pollutants while maintaining high permeability. The resulting SnO2-MXene / PES membrane, possessing antifouling and self-cleaning properties, can be applied in wastewater treatment.

[0031] 3. This invention introduces a metal oxide (SnO2) with photocatalytic properties into a polymer ultrafiltration membrane (PES) to rapidly degrade pollutants using its photocatalytic properties, thereby obtaining a novel ultrafiltration membrane with antifouling activity. In order to improve the loading of photocatalyst on the polymer membrane, this invention introduces a two-dimensional transition metal carbon / nitride (MXene) into the polymer ultrafiltration membrane mixed with metal oxide. The two have a synergistic effect, which improves both the antifouling ability and the separation ability of the composite membrane.

[0032] 4. Polyethersulfone (PES) polymers have relatively few active sites, and their loading capacity for nano-metal oxides is far from achieving active antifouling performance. To improve the capacity of polymer membranes, it is necessary to introduce more active sites to enhance their catalytic performance. However, the increase in active sites leads to an increased load on the catalytic material by the polymer membrane, further promoting the aggregation of the catalytic material and the formation of non-selective voids in the polymer membrane, severely affecting the membrane's selectivity. Therefore, balancing membrane separation function and photodegradation capability is crucial for constructing high-performance ultrafiltration membranes. MXene, as an emerging two-dimensional (2D) transition metal carbide / nitride material, possesses excellent properties such as high specific surface area, hydrophilicity, and high carrier mobility, exhibiting excellent dye separation efficiency in catalytic membrane-based water treatment. As a two-dimensional material with a high specific surface area, MXene has abundant active sites, which can significantly enhance the loading capacity of metal oxide materials. Utilizing MXene nanosheets achieves solute retention while simultaneously creating electron transport channels for photocatalytic particles to reduce photogenerated electron-hole complexation and improve membrane photocatalytic efficiency. Furthermore, MXene, due to its abundant surface functional groups (-OH, -F, -O) and high adsorption capacity, significantly contributes to improving the hydrophilicity of polymer membranes and mitigating membrane fouling. Among wide-bandgap semiconductors, SnO2 possesses unique advantages in long-term stability, diverse microstructures, and excellent biocompatibility. Besides its catalytic effect, the introduction of SnO2 can also improve the mechanical properties of polymer membranes. Therefore, introducing MXene and SnO2 into polymer membranes is an effective strategy for addressing membrane fouling problems.

[0033] 5. By adding a specific proportion of compounded tin oxide, this invention can improve the flux and rejection rate of BSA solution for PES composite ultrafiltration membranes modified with MXene materials.

[0034] 6. This invention, by preparing modified PES powder, can improve the hydrophilicity of PES composite ultrafiltration membranes modified with MXene materials, thereby increasing their fouling resistance. It can also improve the long-term stability of PES composite ultrafiltration membranes modified with MXene materials. Attached Figure Description

[0035] Figure 1 This is a comparison diagram of the contact angles of Example 1 and Comparative Example 2;

[0036] Figure 2 This is a schematic diagram showing the PES flux and retention test results before and after modification in Example 1;

[0037] Figure 3 This is a schematic diagram showing the self-cleaning performance test results of the PES membrane in Example 2;

[0038] Figure 4 This is a schematic diagram showing the flux and retention test results of methylene blue before and after modification in Example 3. Detailed Implementation

[0039] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] The percentage content of raw materials used in Examples 1-3 and Comparative Examples 1-3 is shown in Table 1:

[0041] Table 1. Preparation parameters of composite films with different MXene / SnO2 / PES ratios

[0042]

[0043] Example 1

[0044] This embodiment provides a method for preparing a PES composite ultrafiltration membrane based on MXene material modification, including the following steps:

[0045] (1) Weigh the corresponding raw materials according to Table 1;

[0046] (2) Disperse SnO2, MXene and PVP in DMAc, and then sonicate for 1-3 hours to obtain a mixture;

[0047] (3) Add the modified PES powder to the mixture and stir at 80°C for 6 hours until the PES powder is completely dissolved to obtain the casting liquid;

[0048] (4) Defoaming the casting solution: At room temperature, use a casting blade (200μm) to evenly coat the casting solution onto a smooth glass plate. Then, slowly place the glass plate into a deionized water condensation bath. As the phase change is completed, the membrane automatically separates from the glass plate. Keep the membrane in deionized water for 20 hours to fully remove excess solvent and obtain a PES composite ultrafiltration membrane modified with MXene material.

[0049] SnO2 comprises tin oxide A, tin oxide B, and tin oxide C in a mass ratio of 1:1.3:0.5; the average particle size of tin oxide A is 20-50 nm, and the specific surface area is 75-98 m². 2 / g; the average particle size of tin oxide B is 150-200nm, and the specific surface area is 34-51m². 2 / g; the average particle size of tin oxide B is 300-400nm, and the specific surface area is 9-16m². 2 / g; all ordered from Beijing Juguang Wintech Technology Co., Ltd.

[0050] MXene is a Ti3C2Tx wafer with 1-5 layers and a radial dimension of 0.5-2 μm. It was purchased from Scientific Compass, catalog number FMO410206.

[0051] The viscosity-average molecular weight of PVP is 3000-7000. It was purchased from Boai New Open Source Medical Technology Group Co., Ltd.

[0052] The preparation method of modified PES powder includes the following steps:

[0053] (1) Hydroquinone, 2,5-dihydroxyterephthalic acid, 4,4'-dichlorodiphenyl sulfone, dimethyl sulfoxide, toluene, and anhydrous potassium carbonate were mixed. The mass ratio of hydroquinone, sodium 3-(4-(-2,6'-difluorophenylcarbonyl)phenyl)propanesulfonate, 4,4'-difluorodiphenyl sulfone, dimethyl sulfoxide, toluene, and anhydrous potassium carbonate was 7:14:44:295:120:73. The mixture was heated to 152°C under nitrogen protection and stirring, and kept at this temperature for 5 hours. Then, the temperature was increased to 169°C and the reaction continued for another 5 hours to obtain the polymer product. The polymer product was cooled and solidified, pulverized, washed three times with boiling deionized water, and then refluxed with 37wt% hydrochloric acid for 27 hours. The mixture was filtered, washed with deionized water, dried, and pulverized to a particle size of less than 9μm to obtain carboxylated modified polyethersulfone powder.

[0054] (2) 3-isocyanate-propyltrimethoxysilane (CAS: 15396-00-6, purchased from Shanghai Ruichu Biotechnology Co., Ltd.) and carboxylated modified polyethersulfone powder were mixed and sonicated for 25 min; then toluene was added, heated to 107℃ and stirred for 3 h, toluene was recovered by vacuum distillation, the solid product was washed twice with ethanol and then freeze-dried to obtain silane-modified polyethersulfone powder; the mass ratio of 3-isocyanate-propyltrimethoxysilane, carboxylated modified polyethersulfone powder and toluene was 1.1:0.1:65;

[0055] (3) Add 0.03 parts by weight of silane-modified polyethersulfone powder to 32 parts by weight of ethanol and sonicate for 25 min to prepare an alcohol solution; weigh 0.03 parts by weight of nano TiO2 and add it to 27 parts by weight of deionized water, sonicate for 25 min to prepare a TiO2 aqueous solution;

[0056] (4) Under stirring conditions, TiO2 aqueous solution was added dropwise to alcohol solution, and the mass ratio of silane modified polyethersulfone powder to nano TiO2 was 10:3; the mixture was heated to 60-65℃ and stirred for 3 hours. The supernatant was removed by centrifugation, and the mixture was washed 3-4 times with deionized water and freeze-dried to obtain modified PES powder.

[0057] Nano-TiO2 includes nano-TiO2Ⅰ, nano-TiO2Ⅱ, and nano-TiO2Ⅲ in a mass ratio of 1.4:1:0.6; the average primary particle size of TiO2Ⅰ is 15 nm, and the specific surface area is 30-100 m².2 / g (model DK405); Nano TiO2Ⅱ has an average primary particle size of 60nm and a specific surface area of ​​20-60m². 2 The average primary particle size of / g(DK405-2) and nano-TiO2Ⅲ is 200nm, and the specific surface area is 15m². 2 / g(DK405-3). Purchased from Beijing Deco Island Gold Technology Co., Ltd.

[0058] The surface hydrophilicity of the PES membrane obtained in Example 1 was tested. The sample was cut into strips and dried in a vacuum oven. During the test, the water droplet volume was controlled to 3 μl. After contacting the membrane surface for 3 seconds, an image was recorded and the contact angle was analyzed. To reduce error, each sample was tested at least three times, and the average value was taken as the contact angle of that sample. See details... Figure 1 .

[0059] The water flux and retention capacity of the PES composite ultrafiltration membrane modified with MXene material obtained in Example 1 were tested, and an effective area of ​​7.07 cm² was selected. 2 The membrane was tested for permeability and separation performance using cross-flow filtration. Test method: The membrane was initially compacted at a transmembrane pressure of 0.2 MPa for 30 min until a stable water flux was obtained. Then, the operating pressure was adjusted to 0.1 MPa, and the pure water flux of the membrane was measured. Pure water flux J (L·m³) -2 ·h -1 The calculation is as shown in equation (1):

[0060]

[0061] Where Q(L) is the effective membrane area A(m²) passing through the membrane during the operating time T(h). 2 The permeation volume of ).

[0062] To test the membrane's separation performance, the feed solution was changed to BSA (1 g·L⁻¹). -1 ) and MB (10 mg·L -1 The solution was then used. The permeate concentration of the resulting membrane was measured at wavelengths of 280 nm and 597 nm using a UV spectrophotometer. The membrane retention rate R (%) was estimated using equation (2):

[0063]

[0064] Where Cp and Cf represent the concentrations in the permeate and feed liquid, respectively.

[0065] The results are as follows Figure 2 As shown.

[0066] Example 2

[0067] This embodiment provides a method for preparing a PES composite ultrafiltration membrane based on MXene material modification, including the following steps:

[0068] (1) Weigh the corresponding raw materials according to Table 1;

[0069] (2) Disperse SnO2, MXene and PVP in DMAc, and then sonicate for 1-3 hours to obtain a mixture;

[0070] (3) Add the modified PES powder to the mixture and stir at 90°C for 4 hours until the PES powder is completely dissolved to obtain the casting liquid;

[0071] (4) Defoaming the casting solution: At room temperature, use a casting blade (200μm) to evenly coat the casting solution onto a smooth glass plate. Then, slowly place the glass plate into a deionized water condensation bath. As the phase change is completed, the membrane automatically separates from the glass plate. Keep the membrane in deionized water for 12 hours to fully remove excess solvent and obtain a PES composite ultrafiltration membrane modified with MXene material.

[0072] SnO2 comprises tin oxide A, tin oxide B, and tin oxide C in a mass ratio of 1:1.2:0.4; the average particle size of tin oxide A is 20-50 nm, and the specific surface area is 75-98 m². 2 / g; the average particle size of tin oxide B is 150-200nm, and the specific surface area is 34-51m². 2 / g; the average particle size of tin oxide B is 300-400nm, and the specific surface area is 9-16m². 2 / g; all ordered from Beijing Juguang Wintech Technology Co., Ltd.

[0073] MXene is a Ti3C2Tx wafer with 1-5 layers and a radial dimension of 0.5-2 μm.

[0074] The viscosity-average molecular weight of PVP is 3000-7000. It was purchased from Boai New Open Source Medical Technology Group Co., Ltd.

[0075] The preparation method of modified PES powder includes the following steps:

[0076] (1) Hydroquinone, 2,5-dihydroxyterephthalic acid, 4,4'-dichlorodiphenyl sulfone, dimethyl sulfoxide, toluene, and anhydrous potassium carbonate were mixed. The mass ratio of hydroquinone, sodium 3-(4-(-2,6'-difluorophenylcarbonyl)phenyl)propanesulfonate, 4,4'-difluorodiphenyl sulfone, dimethyl sulfoxide, toluene, and anhydrous potassium carbonate was 6:13:43:290:120:72. The mixture was heated to 150°C under nitrogen protection and stirring, and kept at this temperature for 4 hours. Then, the temperature was increased to 168°C and the reaction was continued for another 4 hours to obtain the polymer product. The polymer product was cooled and solidified, pulverized, washed twice with boiling deionized water, and then refluxed with 36wt% hydrochloric acid for 25 hours. The mixture was filtered, washed with deionized water, dried, and pulverized to a particle size of less than 9μm to obtain carboxylated modified polyethersulfone powder.

[0077] (2) 3-isocyanate-propyltrimethoxysilane (CAS: 15396-00-6, purchased from Shanghai Ruichu Biotechnology Co., Ltd.) and carboxylated modified polyethersulfone powder were mixed and sonicated for 30 min; then toluene was added, heated to 105℃ and stirred for 2-3 h, toluene was recovered by vacuum distillation, the solid product was washed twice with ethanol and then freeze-dried to obtain silane-modified polyethersulfone powder; the mass ratio of 3-isocyanate-propyltrimethoxysilane, carboxylated modified polyethersulfone powder and toluene was 1:0.1:60;

[0078] (3) Add 0.03 parts by weight of silane-modified polyethersulfone powder to 30 parts by weight of ethanol and sonicate for 20 min to prepare an alcohol solution; weigh 0.03 parts by weight of nano TiO2 and add it to 25 parts by weight of deionized water, sonicate for 20 min to prepare a TiO2 aqueous solution;

[0079] (4) Under stirring conditions, TiO2 aqueous solution was added dropwise to alcohol solution, and the mass ratio of silane modified polyethersulfone powder to nano TiO2 was 10:1; the mixture was heated to 60°C and stirred for 2 hours. The supernatant was removed by centrifugation, washed three times with deionized water, and freeze-dried to obtain modified PES powder.

[0080] Nano-TiO2 includes nano-TiO2Ⅰ, nano-TiO2Ⅱ, and nano-TiO2Ⅲ in a mass ratio of 1.3:1:0.5; the average primary particle size of TiO2Ⅰ is 15 nm, and the specific surface area is 30-100 m². 2 / g (model DK405); Nano TiO2Ⅱ has an average primary particle size of 60nm and a specific surface area of ​​20-60m². 2 The average primary particle size of / g(DK405-2) and nano-TiO2Ⅲ is 200nm, and the specific surface area is 15m². 2 / g(DK405-3). Purchased from Beijing Deco Island Gold Technology Co., Ltd.

[0081] The self-cleaning performance of the PES composite ultrafiltration membrane modified with MXene material obtained in Example 2 was tested. The self-cleaning performance of membrane M4 was evaluated by ultraviolet light irradiation (365nm, 36W). Test method: Unstable MB (10mg·L⁻¹) dye deposits on the membrane surface were first washed with deionized water. Then, the contaminated membrane was immersed in deionized water and placed under an ultraviolet lamp for photodegradation until the membrane surface was close to its original color before removal. The separation performance of the treated membrane was then tested again. The above steps were repeated for a total of three cycles.

[0082] Test results are as follows Figure 3 As shown, with increasing filtration time, the deposition of dye molecules on the membrane surface leads to pore blockage, increasing the retention of MB molecules and thus gradually reducing the permeation flux of water molecules through the membrane. Subsequently, under UV irradiation, SnO2 generates photogenerated electrons, promoting the decomposition of the dye and thus promoting the recovery of membrane flux. After three cycles of testing, the MB retention rate was still higher than 95%, proving that long-term light exposure and the effects of oxides do not damage the membrane structure.

[0083] Example 3

[0084] The difference between this embodiment and Embodiment 1 is that the percentage content of raw material mass in Table 1 is different.

[0085] The Methylene blue flux and retention capacity of the PES composite ultrafiltration membrane modified with MXene material obtained in Example 3 were tested, and the results are as follows: Figure 4 As shown.

[0086] Comparative Example 1

[0087] The difference between this comparative example and Example 1 is that the mass percentage of the raw materials in Table 1 is different.

[0088] Comparative Example 2

[0089] The difference between this comparative example and Example 1 is that the mass percentage of the raw materials in Table 1 is different.

[0090] Comparative Example 3

[0091] The difference between this comparative example and Example 1 is that the mass percentage of the raw materials in Table 1 is different.

[0092] Comparative Example 4

[0093] The difference between this comparative example and Example 1 is that the preparation method of the modified PES powder is different.

[0094] The preparation method of modified PES powder includes the following steps: hydroquinone, 2,5-dihydroxyterephthalic acid, 4,4'-dichlorodiphenyl sulfone, dimethyl sulfoxide, toluene, and anhydrous potassium carbonate are mixed, with the mass ratio of hydroquinone, sodium 3-(4-(-2,6'-difluorophenylcarbonyl)phenyl)propanesulfonate, 4,4'-difluorodiphenyl sulfone, dimethyl sulfoxide, toluene, and anhydrous potassium carbonate being 7:14:44:295:120:73; under nitrogen protection and stirring, the mixture is heated to 152°C and reacted for 5 hours, then the temperature is increased to 169°C and the reaction continues for another 5 hours to obtain a polymerization product; the polymerization product is cooled and solidified, pulverized, washed three times with boiling deionized water, and then refluxed with 37wt% hydrochloric acid for 27 hours, filtered, washed with deionized water, dried, and pulverized to a particle size of less than 9 μm to obtain modified polyethersulfone powder.

[0095] Comparative Example 5

[0096] The difference between this comparative example and Example 1 is that the SnO2 comprises tin oxide A, tin oxide B, and tin oxide C in a mass ratio of 1:1:1; the average particle size of tin oxide A is 20-50 nm, and the specific surface area is 75-98 m². 2 / g; the average particle size of tin oxide B is 150-200nm, and the specific surface area is 34-51m². 2 / g; the average particle size of tin oxide B is 300-400nm, and the specific surface area is 9-16m². 2 / g; all ordered from Beijing Juguang Wintech Technology Co., Ltd.

[0097] Comparative Example 6

[0098] The difference between this comparative example and Example 1 is that the modified PES powder was replaced with commercially available PES powder, which was purchased from Scientific Compass, catalog number FMO410206.

[0099] Comparative Example 7

[0100] The difference between this comparative example and Example 1 is that the nano-TiO2 includes nano-TiO2Ⅰ, nano-TiO2Ⅱ, and nano-TiO2Ⅲ in a mass ratio of 1:1:1; the average primary particle size of TiO2Ⅰ is 15nm, and the specific surface area is 30-100m². 2 / g (model DK405); Nano TiO2Ⅱ has an average primary particle size of 60nm and a specific surface area of ​​20-60m². 2 The average primary particle size of / g(DK405-2) and nano-TiO2Ⅲ is 200nm, and the specific surface area is 15m². 2 / g(DK405-3). Purchased from Beijing Deco Island Gold Technology Co., Ltd.

[0101] Performance testing

[0102] The MXene-modified PES composite ultrafiltration membranes prepared in Examples 1-3 and Comparative Examples 1-7 were cut into circular membrane sheets with a diameter of 5 cm, placed in a membrane tank, and pre-pressed at 0.15 MPa for 30 min. Then, under the conditions of 25 °C and 0.1 MPa, the flux of 3 wt% BSA (bovine serum albumin) solution in each group of MXene-modified PES composite ultrafiltration membranes was measured by cross-flow filtration. The volume of 3 wt% BSA solution permeating through the membrane was recorded at a certain time. The flux of 3 wt% BSA solution in the membrane was calculated by formula.

[0103]

[0104] In the formula: JW is the flux of the membrane with 3wt% BSA solution (L·m). -2 ·h -1 Vt is the volume (L) of 3wt% BSA solution that permeates through the membrane during time Δt; A is the effective area of ​​the membrane (m²). 2 ); △t is the sampling time (h). After the flux stabilizes, samples of permeate and feed solution are taken and their absorbance is measured by ultraviolet spectrophotometer at a wavelength of 280 nm. The membrane rejection rate is then calculated using Beer-Lambert's law.

[0105]

[0106] In the formula: R is the rejection rate (%) of the PES composite ultrafiltration membrane modified with MXene material to BSA solution; At is the absorbance value of the feed solution; A0 is the absorbance value of the permeate.

[0107] Each of the above groups of PES composite ultrafiltration membranes modified with MXene material was run in a 3% BSA solution with the same parameters for 96 hours. The flux was measured, and after washing with water, the flux was measured again. The changes in flux were observed and the data were recorded.

[0108] The results are shown in Table 1.

[0109] Table 1 Performance test results of PES composite ultrafiltration membrane modified with MXene material

[0110] flux Retention rate Flux after 96 hours Flux after washing unit <![CDATA[L·m -2 ·h -1 ]]> ％ <![CDATA[L·m -2 ·h -1 ]]> <![CDATA[L·m -2 ·h -1 ]]> Example 1 202.5 98.34 152.6 193.7 Example 2 200.8 97.87 147.1 190.2 Example 3 201.2 97.92 151.2 191.4 Comparative Example 1 170.8 96.24 104.55 147.6 Comparative Example 2 182.2 96.87 112.91 159.7 Comparative Example 3 184.7 96.91 115.46 157.9 Comparative Example 4 173.5 96.12 108.23 144.2 Comparative Example 5 181.3 94.79 118.08 158.4 Comparative Example 6 160.9 95.88 89.67 134.8 Comparative Example 7 192.6 97.24 145.37 175.4

[0111] The performance test results above show that Examples 1-2 have high throughput and rejection rate, and good stability.

[0112] The comparative examples, lacking the necessary technical solutions, showed significantly inferior performance compared to the exemplary examples. In Comparative Example 1, the absence of MXene and tin oxide resulted in a decrease in the overall performance of the MXene-modified PES composite ultrafiltration membrane. Comparative Example 2, which did not use MXene, and Comparative Example 3, which did not add tin oxide, both negatively impacted the performance of the MXene-modified PES composite ultrafiltration membrane, demonstrating the synergistic effect of their combination. In Comparative Example 4, the absence of nano-titanium oxide grafting, and in Comparative Example 7, the different proportions of nano-titanium oxide, led to a decrease in the flux and rejection rate of the MXene-modified PES composite ultrafiltration membrane. In Comparative Example 5, the different particle size distribution of tin oxide resulted in a decrease in both flux and rejection rate of the MXene-modified PES composite ultrafiltration membrane. In Comparative Example 6, replacing the modified PES powder with commercially available PES powder resulted in performance lower than that of Examples 1-3. These experimental results further demonstrate the importance of the technical solutions defined in this invention for its technical effectiveness.

[0113] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a PES composite ultrafiltration membrane based on MXene material modification, characterized in that, Includes the following steps: (1) Weigh the raw materials according to the following mass percentages: 16-20% modified PES powder, 0.08-0.13% SnO2, 0.01-0.03% MXene, 0.8-1.5% PVP and the balance is DMAc; (2) SnO2, MXene and PVP were dispersed in DMAc and then subjected to ultrasonic treatment for 1-3 hours to obtain a mixture; (3) Add the modified PES powder to the mixture and stir at 60-90℃ for 4-8 hours until the PES powder is completely dissolved to obtain the casting liquid; (4) Defoaming the casting liquid, uniformly coating the casting liquid onto the glass plate at room temperature, and then placing the glass plate in a deionized water condensation bath. As the phase change is completed, the membrane automatically separates from the glass plate. The membrane is kept in deionized water for 12-24 hours to obtain a PES composite ultrafiltration membrane modified with MXene material. SnO2 comprises tin oxide A, tin oxide B, and tin oxide C in a mass ratio of 1:(1.2-1.5):(0.4-0.7); the average particle size of tin oxide A is 20-50 nm, and the specific surface area is 75-98 m². 2 / g; the average particle size of tin oxide B is 150-200nm, and the specific surface area is 34-51m². 2 / g; the average particle size of tin oxide B is 300-400nm, and the specific surface area is 9-16m². 2 / g; The preparation method of modified PES powder includes the following steps: (1) Hydroquinone, 2,5-dihydroxyterephthalic acid, 4,4'-dichlorodiphenyl sulfone, dimethyl sulfoxide, toluene and anhydrous potassium carbonate are mixed and heated to 150-155°C under nitrogen protection and stirring. After reacting at this temperature for 4-6 hours, the temperature is raised to 168-170°C and the reaction continues for another 4-6 hours to obtain the polymer product. The polymer product was cooled and solidified, crushed, washed, refluxed and acidified, filtered, washed, dried and crushed to a particle size of less than 9 μm to obtain carboxylated modified polyethersulfone powder. (2) Mix 3-isocyanate-propyltrimethoxysilane and carboxylated modified polyethersulfone powder, sonicate for 20-30 min; then add toluene, heat to 105-100℃ and stir for 2-3 h, recover toluene by vacuum distillation, wash the solid product, freeze dry to obtain silane-modified polyethersulfone powder. (3) Add 0.03 parts by weight of silane-modified polyethersulfone powder to 30-35 parts by weight of ethanol and sonicate for 20-30 min to prepare an alcohol solution; weigh 0.03 parts by weight of nano TiO2 and add it to 25-30 parts by weight of deionized water, sonicate for 20-30 min to prepare a TiO2 aqueous solution; (4) Under stirring conditions, TiO2 aqueous solution was added dropwise to alcohol solution, heated to 60-65℃, stirred for 2-4 hours, centrifuged to remove supernatant, washed, and freeze-dried to obtain modified PES powder.

2. The method for preparing a PES composite ultrafiltration membrane based on MXene material modification according to claim 1, characterized in that, MXene is a Ti3C2Tx wafer with 1-5 layers and a radial dimension of 0.5-2 μm.

3. The method for preparing a PES composite ultrafiltration membrane based on MXene material modification according to claim 1, characterized in that, The viscosity-average molecular weight of PVP is 3000-7000.

4. The method for preparing a PES composite ultrafiltration membrane based on MXene material modification according to claim 1, characterized in that, The mass of hydroquinone, sodium 3-(4-(-2,6'-difluorophenylcarbonyl)phenyl)propanesulfonate, 4,4'-difluorodiphenyl sulfone, dimethyl sulfoxide, toluene and anhydrous potassium carbonate is (6-8):(13-15):(43-45):(290-300):120:(72-75).

5. The method for preparing a PES composite ultrafiltration membrane based on MXene material modification according to claim 1, characterized in that, The mass ratio of 3-isocyanate-propyltrimethoxysilane, carboxylated modified polyethersulfone powder and toluene is (1-1.2):0.1:(60-70).

6. The method for preparing a PES composite ultrafiltration membrane based on MXene material modification according to claim 1, characterized in that, The mass ratio of silane-modified polyethersulfone powder to nano-TiO2 is 10:(1-3).

7. The method for preparing a PES composite ultrafiltration membrane based on MXene material modification according to claim 1, characterized in that, Nano-TiO2 includes nano-TiO2Ⅰ, nano-TiO2Ⅱ and nano-TiO2Ⅲ with a mass ratio of (1.3-1.5):1:(0.5-0.7); The average primary particle size of TiO2Ⅰ is 15 nm, and the specific surface area is 30-100 m². 2 / g; the average primary particle size of nano-TiO2Ⅱ is 60nm, and the specific surface area is 20-60m². 2 / g and the average primary particle size of nano TiO2Ⅲ is 200nm, with a specific surface area of ​​15m². 2 / g.

8. A PES composite ultrafiltration membrane based on MXene material modification prepared by the preparation method according to any one of claims 1-7.

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