A preparation method of a polyether sulfone ultrafiltration membrane based on magnetic field-induced superparamagnetic ferroferric oxide nanoparticle blending doping modification

Abstract

The application relates to a preparation method of a polyether sulfone ultrafiltration membrane modified by blending and doping based on magnetic field induced superparamagnetic ferroferric oxide nanoparticles. The application belongs to the field of membrane material preparation and particularly relates to a preparation method of a polyether sulfone ultrafiltration membrane modified by blending and doping based on magnetic field induced superparamagnetic ferroferric oxide nanoparticles. The application aims to solve the problems that most additives are dispersed in the membrane matrix during the blending and doping modification process, the surface hydrophilicity modification efficiency of the membrane is low, the nanoparticles in the pore size distribution cause too large mass transfer resistance in the filtering process, and the energy consumption is increased. The method comprises the following steps: I, preparing magnetic Fe3O4 nanoparticles; II, preparing a membrane casting solution; III, coating the membrane; IV, performing a non-solvent induced phase separation reaction to obtain a polyether sulfone ultrafiltration membrane blended and doped with Fe3O4 nanoparticles. The application can be applied to the fields of municipal drinking water treatment, protein separation and purification, and reclaimed water, etc.

Description

Technical Field

[0001] This invention belongs to the field of membrane material preparation, specifically relating to a method for preparing a polyethersulfone ultrafiltration membrane based on magnetic field-induced superparamagnetic iron oxide nanoparticles co-doping modification. Background Technology

[0002] Ultrafiltration membrane technology, as a green and efficient technology, has been widely used in separation and purification in industries such as environment, medicine, and chemicals. Organic membrane materials are currently the most diverse and widely used membrane materials, including polyethersulfone, polysulfone, polyvinylidene fluoride, polytetrafluoroethylene, polyamide, and cellulose. Compared with inorganic membranes, organic membranes are simpler, faster to produce, and cheaper.

[0003] However, organic ultrafiltration membranes are easily fouled by hydrophobic organic matter and proteins during practical applications, which reduces ultrafiltration membrane flux, increases operating pressure, shortens membrane lifespan, and raises operating costs. Therefore, improving the hydrophilicity of ultrafiltration membranes remains a key focus of research. Currently, the main methods to improve hydrophilicity are modification techniques, including blending modification during membrane preparation and post-treatment surface modification of the prepared base membrane.

[0004] Some inorganic materials exhibit advanced catalytic and adsorption activities, and the preparation of organic-inorganic composite membranes by blending and modifying organic ultrafiltration membranes with inorganic materials has been widely used. However, during the treatment process, some nanoparticles are dispersed in the membrane matrix, resulting in fewer nanoparticles on the membrane surface and reduced effective utilization. Summary of the Invention

[0005] This invention aims to address the problems of low efficiency in hydrophilic modification of the membrane surface and excessive mass transfer resistance and energy consumption caused by nanoparticles distributed within the pore size during the blending and doping process, which are mostly dispersed in the membrane matrix during the blending and doping modification process. The invention provides a method for preparing polyethersulfone ultrafiltration membranes based on magnetic field-induced superparamagnetic iron oxide nanoparticles for blending and doping modification.

[0006] The present invention discloses a method for preparing a polyethersulfone ultrafiltration membrane based on magnetic field-induced superparamagnetic iron oxide nanoparticles co-doped and modified, which comprises the following steps:

[0007] I. Preparation of magnetic Fe3O4 nanoparticles: FeCl3·6H2O and FeCl2·4H2O were added to deionized water and ultrasonically dispersed at room temperature for 10–30 min to obtain a yellow solution; then, under nitrogen protection, the solution was heated in a water bath, and NH3·H2O was slowly added dropwise until the pH > 10 to obtain a precipitate; the precipitate was first washed with deionized water, then washed with anhydrous ethanol, and then vacuum dried at 60–90 °C for 5–12 h, and then ground to obtain superparamagnetic Fe3O4 nanoparticles;

[0008] 2. The superparamagnetic Fe3O4 nanoparticles are ultrasonically dispersed in a solvent, and then the pore-forming agent and polyethersulfone are added to the solvent in sequence and stirred for 8-20 hours to form a casting solution.

[0009] 3. After degassing the casting solution, place it on a support and coat it with a film. After coating, apply a magnetic field in a direction perpendicular to the support to place the film in the magnetic field and obtain a magnetically treated film.

[0010] IV. The magnetically treated membrane is immersed in deionized water at an angle of 45-90° to the liquid surface to carry out a non-solvent-induced phase separation reaction, thereby obtaining a polyethersulfone ultrafiltration membrane with Fe3O4 nanoparticles.

[0011] The beneficial effects of this invention are:

[0012] This invention prepares Fe3O4 nanoparticles via a chemical coprecipitation method. The preparation process is simple and low-cost. The nanoparticles migrate to the membrane surface under magnetic field drive, increasing the nanoparticle content on the membrane surface and maximizing the function of Fe3O4 nanoparticles, thus significantly improving the membrane performance.

[0013] The preparation method of this invention first adjusts the ratio of polymer and pore-forming agent in the casting solution, and then optimizes the addition content of nanoparticles. This allows for efficient control of membrane pure water flux, rejection rate, hydrophilicity and antifouling performance, and has industrial practical value in the fields of municipal water treatment, protein separation and purification and reclaimed water reuse. Attached Figure Description

[0014] Figure 1 TEM image of the superparamagnetic Fe3O4 nanoparticles in Example 1;

[0015] Figure 2 The graph shows the variation of pure water flux in blended membranes with different nanoparticle doping amounts.

[0016] Figure 3 The graph shows the variation of BSA retention performance in blend films with different nanoparticle doping amounts. Detailed Implementation

[0017] Specific Implementation Method 1: The preparation method of a polyethersulfone ultrafiltration membrane based on magnetic field-induced superparamagnetic iron oxide nanoparticles with co-doping modification is carried out according to the following steps:

[0018] I. Preparation of magnetic Fe3O4 nanoparticles: FeCl3·6H2O and FeCl2·4H2O were added to deionized water and ultrasonically dispersed at room temperature for 10–30 min to obtain a yellow solution; then, under nitrogen protection, the solution was heated in a water bath, and NH3·H2O was slowly added dropwise until the pH > 10 to obtain a precipitate; the precipitate was first washed with deionized water, then washed with anhydrous ethanol, and then vacuum dried at 60–90 °C for 5–12 h, and then ground to obtain superparamagnetic Fe3O4 nanoparticles;

[0019] 2. The superparamagnetic Fe3O4 nanoparticles are ultrasonically dispersed in a solvent, and then the pore-forming agent and polyethersulfone are added to the solvent in sequence and stirred for 8-20 hours to form a casting solution.

[0020] 3. After degassing the casting solution, place it on a support and coat it with a film. After coating, apply a magnetic field in a direction perpendicular to the support to place the film in the magnetic field and obtain a magnetically treated film.

[0021] IV. The magnetically treated membrane is immersed in deionized water at an angle of 45-90° to the liquid surface to carry out a non-solvent-induced phase separation reaction, thereby obtaining a polyethersulfone ultrafiltration membrane with Fe3O4 nanoparticles.

[0022] The polyethersulfone ultrafiltration membrane with Fe3O4 nanoparticles prepared in this embodiment has applications in municipal drinking water treatment, protein separation and purification, and reclaimed water; it greatly improves hydrophilicity, retention and antifouling performance, extends membrane life, and reduces operating costs.

[0023] The principle of preparing polyethersulfone ultrafiltration membranes using magnetic field-induced Fe3O4 nanoparticle co-doping modification is as follows:

[0024] Fe3O4 nanoparticles contain a large number of hydroxyl groups on their surface and exhibit superparamagnetism. Under the influence of a magnetic field, they migrate towards the membrane surface, accelerating solvent diffusion during phase transformation and forming micropores on the membrane surface. This improves membrane separation performance and surface porosity, thereby increasing water flux and retention capacity. The surface hydroxyl groups form hydrogen bonds with water molecules, creating a hydration layer on the membrane surface, effectively preventing membrane fouling. The blended modified ultrafiltration membrane was prepared using a solvent-inducing phase separation method. It was prepared by adding Fe3O4 nanoparticles to a traditional casting solution system.

[0025] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the mass ratio of FeCl3·6H2O and FeCl2·4H2O in step one is (1-3):1. Other steps and parameters are the same as in Specific Implementation Method One.

[0026] Specific Implementation Method Three: This implementation method differs from Specific Implementation Method One or Two in that the water bath heating temperature in step one is 70–90°C. Other steps and parameters are the same as in Specific Implementation Method One or Two.

[0027] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that, in step two, based on the total mass of the casting solution, the casting solution contains 0.05–10% superparamagnetic Fe3O4 nanoparticles, 13–20% polyethersulfone, 0.5–10% pore-forming agent, and the balance is solvent. Other steps and parameters are the same as in Specific Implementation Methods One to Three.

[0028] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that the polyethersulfone mentioned in step two is a polyethersulfone with a degree of polymerization of 5000 to 200000. Other steps and parameters are the same as in Specific Implementation Methods One to Four.

[0029] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that the pore-forming agent mentioned in step two is one or a combination of several of the following: polyvinylpyrrolidone, polyethylene glycol, oxalic acid, ethylene glycol, glycerin, propylene glycol, lithium chloride, and lithium perchlorate. Other steps and parameters are the same as in Specific Implementation Methods One to Five.

[0030] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that the polyvinylpyrrolidone mentioned in step two is a polyvinylpyrrolidone with an average molecular weight of 5,000 to 200,000. Other steps and parameters are the same as in Specific Implementation Methods One to Six.

[0031] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in that the solvent mentioned in step two is one or a combination of several of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, hexamethylphosphoramide, tetramethylurea, triethyl phosphate, and trimethyl phosphate. Other steps and parameters are the same as in Specific Implementation Methods One to Seven.

[0032] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One through Eight in that the coating speed in step three is 20–200 mm / s. -1 The coating thickness is 100–300 μm. Other steps and parameters are the same as in specific embodiments one through eight.

[0033] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods One to Nine in that the intensity of the magnetic field applied in step three is 0.01–0.5T, and the residence time of the membrane in the magnetic field is 15–120s. Other steps and parameters are the same as in Specific Implementation Methods One to Nine.

[0034] The beneficial effects of the present invention are verified using the following embodiments:

[0035] Example 1: A method for preparing a polyethersulfone ultrafiltration membrane based on magnetic field-induced superparamagnetic iron oxide nanoparticles co-doping modification is carried out according to the following steps:

[0036] I. Preparation of Magnetic Fe3O4 Nanoparticles: 11.68 g FeCl3·6H2O and 4.3 g FeCl2·4H2O were added to 200 mL of deionized water and ultrasonically dispersed for 10 min at room temperature to obtain a yellow solution. Then, under nitrogen protection, the solution was heated in a water bath, and NH3·H2O was slowly added dropwise until the pH > 10. The reaction was allowed to proceed for 30 min, followed by natural cooling to obtain a precipitate. The precipitate was washed three times with deionized water and then three times with anhydrous ethanol. It was then vacuum dried at 60–90 °C for 5 h and ground to obtain superparamagnetic Fe3O4 nanoparticles. The water bath heating temperature was 85 °C.

[0037] 2. Fe3O4 nanoparticles were added to N,N-dimethylacetamide and ultrasonically dispersed at a frequency of 70 kHz for 30 min. Then, polyethersulfone resin and polyvinylpyrrolidone with a purity of K30 were added to the ultrasonically dispersed solution. The solution was heated to 60 °C and stirred for 6 h to obtain a casting solution. Based on the total mass of the casting solution, the casting solution contained 1% superparamagnetic Fe3O4 nanoparticles, 15% polyethersulfone resin, 3% polyvinylpyrrolidone with a purity of K30, and the balance being solvent.

[0038] 3. After degassing the casting solution for 6 hours, the casting solution is coated onto a glass plate with a coating thickness of 200 μm and a coating speed of 20 mm / s. Then, a magnetic field with an intensity of 2000 e is applied in the direction perpendicular to the glass plate to pre-convert the film in the magnetic field for 30 seconds.

[0039] IV. The magnetically treated membrane is immersed in deionized water at a 45° angle to the liquid surface to carry out a non-solvent-induced phase separation reaction. After solvent exchange for 24 hours, a polyethersulfone ultrafiltration membrane with Fe3O4 nanoparticle co-doped by magnetic field is obtained.

[0040] Figure 1 The image shows a photograph of the nanoparticles prepared in Example 1. The nanoparticles in the image show only a small amount of agglomeration, indicating that the nanoparticles are well dispersed.

[0041] In this embodiment, the pure water flux and bovine serum albumin (BSA) rejection rate of the magnetic field-induced Fe3O4 nanoparticle co-doped polyethersulfone ultrafiltration membrane were measured using the dead-end filtration method according to the national standard ultrafiltration membrane testing method (GBT 32360-2015) on a Millipore UFSC40001 ultrafiltration cup. The pure water flux was 806.5 L / m³. 2 •h, BSA retention rate was 85.9%.

[0042] Example 2: A method for preparing a polyethersulfone ultrafiltration membrane based on magnetic field-induced superparamagnetic iron oxide nanoparticles co-doping modification is carried out according to the following steps:

[0043] I. Preparation of Magnetic Fe3O4 Nanoparticles: 11.68 g FeCl3·6H2O and 4.3 g FeCl2·4H2O were added to 200 mL of deionized water and ultrasonically dispersed for 10 min at room temperature to obtain a yellow solution. Then, under nitrogen protection, the solution was heated in a water bath, and NH3·H2O was slowly added dropwise until the pH > 10. The reaction was allowed to proceed for 30 min, followed by natural cooling to obtain a precipitate. The precipitate was washed three times with deionized water and then three times with anhydrous ethanol. It was then vacuum dried at 60–90 °C for 5 h and ground to obtain superparamagnetic Fe3O4 nanoparticles. The water bath heating temperature was 85 °C.

[0044] 2. Fe3O4 nanoparticles were added to N,N-dimethylacetamide and ultrasonically dispersed at a frequency of 70 kHz for 30 min. Then, polyethersulfone resin and polyvinylpyrrolidone with a purity of K30 were added to the ultrasonically dispersed solution. The solution was heated to 60 °C and stirred for 6 h to obtain a casting solution. Based on the total mass of the casting solution, the casting solution contained 3% superparamagnetic Fe3O4 nanoparticles, 15% polyethersulfone resin, 3% polyvinylpyrrolidone with a purity of K30, and the balance being solvent.

[0045] 3. After degassing the casting solution for 6 hours, the casting solution is coated onto a glass plate with a coating thickness of 200 μm and a coating speed of 20 mm / s. Then, a magnetic field with an intensity of 2000 e is applied in the direction perpendicular to the glass plate to pre-convert the film in the magnetic field for 30 seconds.

[0046] IV. The magnetically treated membrane is immersed in deionized water at a 60° angle to the liquid surface to carry out a non-solvent-induced phase separation reaction. After solvent exchange for 24 hours, a polyethersulfone ultrafiltration membrane with Fe3O4 nanoparticle co-doped by magnetic field is obtained.

[0047] In this embodiment, the pure water flux and bovine serum albumin (BSA) rejection rate of the magnetic field-induced Fe3O4 nanoparticle co-doped polyethersulfone ultrafiltration membrane were measured using the dead-end filtration method according to the national standard ultrafiltration membrane testing method (GBT 32360-2015) on a Millipore UFSC40001 ultrafiltration cup. The pure water flux was 876.7 L / m³. 2 •h, BSA retention rate was 88.9%.

[0048] Example 3: A method for preparing a polyethersulfone ultrafiltration membrane based on magnetic field-induced superparamagnetic iron oxide nanoparticles co-doping modification is carried out according to the following steps:

[0049] I. Preparation of Magnetic Fe3O4 Nanoparticles: 5.84 g FeCl3·6H2O and 2.15 g FeCl2·4H2O were added to 200 mL of deionized water and ultrasonically dispersed at room temperature for 10 min to obtain a yellow solution. Then, under nitrogen protection, the solution was heated in a water bath, and NH3·H2O was slowly added dropwise until the pH > 10. The reaction was allowed to proceed for 30 min, followed by natural cooling to obtain a precipitate. The precipitate was washed three times with deionized water and then three times with anhydrous ethanol. It was then vacuum dried at 60–90 °C for 5 h and ground to obtain superparamagnetic Fe3O4 nanoparticles. The water bath heating temperature was 85 °C.

[0050] 2. Fe3O4 nanoparticles were added to N,N-dimethylacetamide and ultrasonically dispersed at a frequency of 70 kHz for 30 min. Then, polyethersulfone resin and polyvinylpyrrolidone with a purity of K30 were added to the ultrasonically dispersed solution. The solution was heated to 60 °C and stirred for 6 h to obtain a casting solution. Based on the total mass of the casting solution, the casting solution contained 5% superparamagnetic Fe3O4 nanoparticles, 15% polyethersulfone resin, 3% polyvinylpyrrolidone with a purity of K30, and the balance being solvent.

[0051] 3. After degassing the casting solution for 6 hours, the casting solution is coated onto a glass plate with a coating thickness of 200 μm and a coating speed of 20 mm / s. Then, a magnetic field with an intensity of 2000 e is applied in the direction perpendicular to the glass plate to pre-convert the film in the magnetic field for 30 seconds.

[0052] IV. The magnetically treated membrane is immersed in deionized water at a 60° angle to the liquid surface to carry out a non-solvent-induced phase separation reaction. After solvent exchange for 24 hours, a polyethersulfone ultrafiltration membrane with Fe3O4 nanoparticle co-doped by magnetic field is obtained.

[0053] In this embodiment, the pure water flux and bovine serum albumin (BSA) rejection rate of the magnetic field-induced Fe3O4 nanoparticle co-doped polyethersulfone ultrafiltration membrane were measured using the dead-end filtration method according to the national standard ultrafiltration membrane testing method (GBT 32360-2015) on a Millipore UFSC40001 ultrafiltration cup. The pure water flux was 913.4 L / m³. 2 •h, BSA retention rate was 93.4%.

[0054] Figure 2 The graph shows the changes in pure water flux of blended membranes with different nanoparticle doping amounts. The control membrane is a pure PES ultrafiltration membrane without added nanoparticles. The comparison shows that the pure water flux of the ultrafiltration membrane is significantly improved after adding nanoparticles. Figure 3 The graph shows the variation in BSA retention performance of blended membranes with different nanoparticle doping concentrations. The control membrane is a pure PES ultrafiltration membrane without added nanoparticles. The comparison reveals that the addition of nanoparticles significantly improves the BSA retention performance of the ultrafiltration membrane. Figure 2 and Figure 3 It can be observed that the addition of nanoparticles improves both the pure water flux and retention performance of the composite membrane, breaking the "trade-off" effect between flux and retention, and providing a reference for the preparation of advanced ultrafiltration membranes.

Claims

1. A method for preparing a polyethersulfone ultrafiltration membrane based on magnetic field-induced superparamagnetic iron oxide nanoparticles co-doping modification, characterized in that... The preparation method of polyethersulfone ultrafiltration membrane based on magnetic field-induced superparamagnetic iron oxide nanoparticles co-doping modification is carried out according to the following steps: I. Preparation of magnetic Fe3O4 nanoparticles: FeCl3·6H2O and FeCl2·4H2O were added to deionized water and ultrasonically dispersed at room temperature for 10–30 min to obtain a yellow solution; then, under nitrogen protection, the solution was heated in a water bath, and NH3·H2O was slowly added dropwise until the pH > 10 to obtain a precipitate; the precipitate was first washed with deionized water, then washed with anhydrous ethanol, and then vacuum dried at 60–90 °C for 5–12 h, and then ground to obtain superparamagnetic Fe3O4 nanoparticles; 2. Superparamagnetic Fe3O4 nanoparticles are ultrasonically dispersed in a solvent, and then a pore-forming agent and polyethersulfone are added to the solvent in sequence. The mixture is stirred for 8–20 h to form a casting solution. The casting solution contains 0.05–10% superparamagnetic Fe3O4 nanoparticles, 13–20% polyethersulfone, 0.5–10% pore-forming agent, and the balance being solvent, based on the total mass of the casting solution.

3. After degassing the casting solution, place it on a support and coat it with a film. After coating, apply a magnetic field perpendicular to the support to place the film in the magnetic field, thus obtaining a magnetically treated film. The coating speed is 20–200 mm / s. -1 The coating thickness is 100–300 μm; the applied magnetic field strength is 0.01–0.5 T; and the residence time of the film in the magnetic field is 15–120 s. IV. The magnetically treated membrane is immersed in deionized water at an angle of 45-90° to the liquid surface to carry out a non-solvent-induced phase separation reaction, thereby obtaining a polyethersulfone ultrafiltration membrane with Fe3O4 nanoparticles.

2. The method for preparing a polyethersulfone ultrafiltration membrane based on magnetic field-induced superparamagnetic iron oxide nanoparticles co-doping modification according to claim 1, characterized in that... The mass ratio of FeCl3·6H2O and FeCl2·4H2O in step one is (1-3):

1.

3. The method for preparing a polyethersulfone ultrafiltration membrane based on magnetic field-induced superparamagnetic iron oxide nanoparticles co-doping modification according to claim 1, characterized in that... The water bath heating temperature in step one is 70-90℃.

4. The method for preparing a polyethersulfone ultrafiltration membrane based on magnetic field-induced superparamagnetic iron oxide nanoparticles co-doping modification according to claim 1, characterized in that... The polyethersulfone mentioned in step two is a polyethersulfone with a degree of polymerization of 5,000 to 200,000.

5. The method for preparing a polyethersulfone ultrafiltration membrane based on magnetic field-induced superparamagnetic iron oxide nanoparticles co-doping modification according to claim 1, characterized in that... The pore-forming agent mentioned in step two is one or a combination of several of the following: polyvinylpyrrolidone, polyethylene glycol, oxalic acid, ethylene glycol, glycerin, propylene glycol, lithium chloride, and lithium perchlorate.

6. The method for preparing a polyethersulfone ultrafiltration membrane based on magnetic field-induced superparamagnetic iron oxide nanoparticles co-doping modification according to claim 5, characterized in that... The polyvinylpyrrolidone mentioned in step two is a polyvinylpyrrolidone with an average molecular weight of 5,000 to 200,000.

7. The method for preparing a polyethersulfone ultrafiltration membrane based on magnetic field-induced superparamagnetic iron oxide nanoparticles co-doping modification according to claim 1, characterized in that... The solvent mentioned in step two is one or a combination of several of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide, hexamethylphosphoramide, tetramethylurea, triethyl phosphate, and trimethyl phosphate.

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