Preparation method of Ti-doped ferroferric oxide composite nanoparticles blended modified catalytic polyether sulfone ultrafiltration membrane

Abstract

The application relates to a preparation method of a Ti-doped ferroferric oxide composite nanoparticle blending modified catalytic polyether sulfone ultrafiltration membrane, and aims to solve the problem that in the preparation process of the blending membrane, the catalyst is easily dispersed in the membrane matrix, cannot effectively catalyze the degradation of the membrane surface pollutants, and thus influences the degradation efficiency. The semiconductor catalyst TiO2 is doped on the superparamagnetic Fe3O4 to form Ti-Fe3O4 composite nanoparticles with superparamagnetism. Before phase conversion, the directional driving action of the magnetic field on the composite nanoparticles is utilized to make the Ti-Fe3O4 composite nanoparticles directionally migrate in the casting solution. The catalyst can be enriched on the membrane surface to enhance the degradation efficiency of the membrane surface pollutants, and the catalyst can be fixed to prevent the difficulty in recycling. The application is applied to the water treatment field.

Description

Technical Field

[0001] This invention relates to a method for preparing a Ti-doped iron tetroxide composite nanoparticle blend modified catalytic polyethersulfone ultrafiltration membrane. Background Technology

[0002] In recent years, with the advancement of science and technology and rapid economic development, ultrafiltration technology has been applied to many fields, from chemical separation and recovery, dairy product preparation to drinking water treatment and reclaimed water reuse. However, membrane performance is often limited by membrane fouling: due to the deposition of organic, biological, and colloidal substances on the membrane surface and inside the membrane pores, the membrane flux gradually decreases and the transmembrane pressure gradually increases during operation, increasing operating energy consumption. Natural organic matter is mainly composed of hydrophobic humic substances, which are prone to membrane fouling themselves and can also bridge with other substances in the water, causing even more serious membrane fouling.

[0003] Persulfate oxidation is a typical advanced oxidation technology. Due to its advantages such as being environmentally friendly and safe, the catalytic degradation of pollutants in water using persulfate has received widespread attention in recent years. There are many ways to activate persulfate, including thermal activation, ultraviolet activation, and metal / transition metal activation. Among these activation techniques, metal / transition metal activation, which requires no external energy input, is widely used. Catalysts are the core of catalysis technology. Coupled nanocatalysts with polymer membranes to construct catalytic membrane systems has been developed; this method is environmentally friendly and extends the lifespan of both the catalyst and the membrane material. However, in the preparation of ordinary blended membranes, the catalyst is easily dispersed in the membrane matrix, which cannot effectively catalyze the degradation of pollutants on the membrane surface, thus limiting the degradation efficiency. Summary of the Invention

[0004] The purpose of this invention is to solve the problem that in the preparation process of blended membranes, the catalyst is easily dispersed in the membrane matrix and cannot effectively catalyze the degradation of pollutants on the membrane surface, thus affecting the degradation efficiency. This invention provides a method for preparing a Ti-doped iron tetroxide composite nanoparticle blend-modified catalytic polyethersulfone ultrafiltration membrane.

[0005] The preparation method of the Ti-doped iron oxide composite nanoparticle blend modified catalytic polyethersulfone ultrafiltration membrane according to the present invention is carried out according to the following steps:

[0006] I. Preparation of superparamagnetic Fe3O4 nanoparticles: FeCl3·6H2O and FeCl2·4H2O were added to deionized water and ultrasonically dispersed at room temperature for 10–30 min to obtain mixed solution A; then, under nitrogen protection, the mixture was heated in a water bath, and NH3·H2O was added dropwise to mixed solution A until pH > 10 to obtain precipitate A; precipitate A 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;

[0007] II. Preparation of Ti-Fe3O4 composite catalyst: Superparamagnetic Fe3O4 nanoparticles were dispersed in mixed solution B, then tetrabutyl titanate was added, followed by concentrated sulfuric acid. The mixture was stirred for 60 min to obtain precipitate B. Precipitate B was first washed with deionized water, then washed with anhydrous ethanol, then vacuum dried at 40–60 °C, then calcined at high temperature, and finally ground to obtain superparamagnetic Ti-Fe3O4 composite nanoparticles. Mixed solution B was composed of anhydrous ethanol and acetic acid.

[0008] 3. Ultrasonically disperse the superparamagnetic Ti-Fe3O4 composite nanoparticles in a solvent, then add the pore-forming agent and polymer to the dispersion in sequence, and stir for 8-20 hours to form a casting solution;

[0009] 4. The casting solution is placed under vacuum for degassing treatment, and then the casting solution is coated onto the support. A magnetic field is applied perpendicular to the support, and the mixture is left to stand in the magnetic field for 15-120 seconds. Then the support 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, and a Ti-Fe3O4 blend-modified polyethersulfone ultrafiltration membrane with catalytic function is obtained.

[0010] Fe3O4 nanoparticles exhibit superparamagnetism. Doping them with nano-TiO2 can prepare Ti-Fe3O4 composite nanoparticles. Under magnetic field induction, these Ti-Fe3O4 composite nanoparticles can migrate directionally to the ultrafiltration membrane surface. With the addition of an appropriate concentration of oxidant, the Ti-Fe3O4 nanoparticles on the membrane surface catalytically oxidize and decompose humic substances and proteins in the water, preventing pollutants from adhering to the membrane surface and causing membrane fouling. The surface of the Ti-Fe3O4 composite nanoparticles contains a large number of hydroxyl functional groups, which can significantly improve the hydrophilicity of the membrane surface and also play an antifouling role. The blended modified polyethersulfone ultrafiltration membrane with catalytic function was prepared using a magnetic field-assisted solvent-inducing phase separation method, mainly by co-doping Ti-Fe3O4 composite nanoparticles into a traditional casting solution using an external magnetic field.

[0011] The present invention has the following beneficial effects:

[0012] (1) By doping semiconductor material TiO2 with Fe3O4 nanoparticles to prepare Ti-Fe3O4 composite nanoparticles, persulfate oxidant can be activated to generate free radicals at room temperature without the need for external energy.

[0013] (2) Using a magnetic field-assisted method, superparamagnetic composite nanoparticles with catalytic function are directionally migrated to the surface of the ultrafiltration membrane to prevent the catalyst from being embedded in the polymer matrix and reducing the efficiency of the catalyst; at the same time, it can fix the catalyst and avoid the difficulty of catalyst recovery.

[0014] (3) The composite nanoparticles contain a large number of hydroxyl functional groups on their surface. These groups can migrate to the membrane surface, enhancing the hydrophilicity of the catalytic membrane and improving its antifouling performance. The addition of a catalyst can catalytically degrade pollutants on the membrane surface, reducing membrane fouling. Coupled with the membrane separation process, this can provide new insights into ultrafiltration membrane preparation technology. Attached Figure Description

[0015] Figure 1 Transmission electron microscopy analysis of Ti-Fe3O4 composite nanoparticles;

[0016] Figure 2 The degradation effect of different PDS oxidant concentrations on methylene blue pollutants;

[0017] Figure 3 EDS energy spectrum of the surface of the Ti-doped iron oxide composite nanoparticle blend modified catalytic polyethersulfone ultrafiltration membrane;

[0018] Figure 4 The pure water flux of the catalytic membrane after blending and modification with different contents of Ti-Fe3O4 nanoparticles;

[0019] Figure 5 Figure 1 shows the anti-fouling performance of catalytic membranes modified with different contents of nanoparticles under catalytic oxidation conditions over multiple cycles. Detailed Implementation

[0020] The technical solution of the present invention is not limited to the specific embodiments listed below, but also includes any combination of the specific embodiments.

[0021] Specific Implementation Method 1: This implementation method describes a method for preparing a Ti-doped iron tetroxide composite nanoparticle blend-modified catalytic polyethersulfone ultrafiltration membrane, which is carried out according to the following steps:

[0022] I. Preparation of superparamagnetic Fe3O4 nanoparticles: FeCl3·6H2O and FeCl2·4H2O were added to deionized water and ultrasonically dispersed at room temperature for 10–30 min to obtain mixed solution A; then, under nitrogen protection, the mixture was heated in a water bath, and NH3·H2O was added dropwise to mixed solution A until pH > 10 to obtain precipitate A; precipitate A 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;

[0023] II. Preparation of Ti-Fe3O4 composite catalyst: Superparamagnetic Fe3O4 nanoparticles were dispersed in mixed solution B, then tetrabutyl titanate was added, followed by concentrated sulfuric acid. The mixture was stirred for 60 min to obtain precipitate B. Precipitate B was first washed with deionized water, then washed with anhydrous ethanol, then vacuum dried at 40–60 °C, then calcined at high temperature, and finally ground to obtain superparamagnetic Ti-Fe3O4 composite nanoparticles. Mixed solution B was composed of anhydrous ethanol and acetic acid.

[0024] 3. Ultrasonically disperse the superparamagnetic Ti-Fe3O4 composite nanoparticles in a solvent, then add the pore-forming agent and polymer to the dispersion in sequence, and stir for 8-20 hours to form a casting solution;

[0025] 4. The casting solution is placed under vacuum for degassing treatment, and then the casting solution is coated onto the support. A magnetic field is applied perpendicular to the support, and the mixture is left to stand in the magnetic field for 15-120 seconds. Then the support 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, and a Ti-Fe3O4 blend-modified polyethersulfone ultrafiltration membrane with catalytic function is obtained.

[0026] The Ti-doped iron tetroxide composite nanoparticle blend modified catalytic polyethersulfone ultrafiltration membrane of this application is used to catalyze the degradation of dyes, humic substances or micro-pollutants by PDS.

[0027] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the mass ratio of FeCl3·6H2O and FeCl2·4H2O is 1:1 to 3:1. Everything else is the same as in Specific Implementation Method One.

[0028] Specific Implementation Method 3: This implementation method differs from Specific Implementation Method 1 or 2 in that the volume ratio of anhydrous ethanol to acetic acid in mixed solution B is 1:1 to 1:5. Everything else is the same as in Specific Implementation Method 1 or 2.

[0029] Specific Implementation Method Four: This implementation method differs from Specific Implementation Methods One to Three in that the molar ratio of Fe3O4 nanoparticles to tetrabutyl titanate is 1:1 to 1:20, and the molar ratio of tetrabutyl titanate to concentrated sulfuric acid is 1:1 to 1:10. Everything else is the same as in Specific Implementation Methods One to Three.

[0030] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that the calcination temperature is 300–900°C. Everything else is the same as in Specific Implementation Methods One to Four.

[0031] Specific Implementation Method Six: This implementation method differs from Specific Implementation Methods One to Five in that the solvent mentioned in step three refers to a mixture of one or more of N-methylpyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, and dimethyl sulfoxide in any proportion. Everything else is the same as in Specific Implementation Methods One to Five.

[0032] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that the polymer is polyvinylidene fluoride, polytetrafluoroethylene, polysulfone, or cellulose acetate. Everything else is the same as in Specific Implementation Methods One to Six.

[0033] Polyethersulfone refers to polyethersulfone resin or powder with a degree of polymerization of 10,000 to 200,000.

[0034] Specific Implementation Method Eight: This implementation method differs from Specific Implementation Methods One to Seven in that the pore-forming agent refers to a mixture of one or more of the following: polyvinylpyrrolidone, polyethylene glycol, oxalic acid, ethylene glycol, glycerin, lithium chloride, and lithium perchlorate, mixed in any proportion. Everything else is the same as in Specific Implementation Methods One to Seven.

[0035] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One through Eight in that the coating speed in step four is 20–200 mm / s. -1 The coating thickness is 100–300 μm. Other aspects are the same as in any of the specific embodiments one through eight.

[0036] Specific Implementation Method Ten: This implementation method differs from Specific Implementation Methods One to Nine in that the strength of the magnetic field applied in step four is 0.001 to 1 T. Everything else is the same as in Specific Implementation Methods One to Nine.

[0037] The beneficial effects of the present invention are verified using the following embodiments:

[0038] Example 1

[0039] The preparation method of Ti-doped iron(III) oxide composite nanoparticle blend modified catalytic polyethersulfone ultrafiltration membrane in this embodiment is carried out according to the following steps: (1) Preparation of superparamagnetic Fe3O4 nanoparticles: 11.68g FeCl3·6H2O and 4.3g FeCl2·4H2O were dissolved in 300ml deionized water, the solution was transferred to a three-necked flask, ultrasonically dispersed, stirred and heated to 85℃. NH3·H2O was added to the solvent to adjust the pH to 10, and the reaction was carried out for 0.5h. After cooling to room temperature, the product was washed three times with deionized water and anhydrous ethanol, respectively, and dried in a vacuum drying oven at 80℃. The product was then ground to obtain superparamagnetic Fe3O4 nanoparticles.

[0040] (2) Preparation of Ti-Fe3O4 composite catalyst: 5g of superparamagnetic Fe3O4 nanoparticles were dispersed in 500mL of a mixed solution and ultrasonically dispersed. Then, 50mL of tetrabutyl titanate and 24mL of concentrated sulfuric acid were added, and the mixture was stirred vigorously for 60min. The precipitate was washed three times with deionized water and three times with anhydrous ethanol. The product was dried in a vacuum drying oven at 40℃. Finally, the dried product was calcined in a muffle furnace at 450℃ for 5h and ground to obtain superparamagnetic Ti-Fe3O4 nanoparticles. The mixed solution was composed of 200mL of anhydrous ethanol and 300mL of acetic acid.

[0041] (3) Add Ti-Fe3O4 nanoparticles to N,N-dimethylacetamide, then add polyvinylpyrrolidone and polyethersulfone resin, stir for 8 hours to obtain casting solution, wherein Ti-Fe3O4 nanoparticles are 0.45wt%, N,N-dimethylacetamide is 81.55wt%, polyvinylpyrrolidone is 3wt%, and polyethersulfone resin is 15wt%.

[0042] (4) Place the casting solution in a vacuum for 4 hours to allow it to stand and degas. Then, take a glass plate as a support and apply the casting solution evenly to the glass plate.

[0043] (5) Place the glass plate perpendicular to the magnetic field and leave it in the magnetic field for 30 seconds. Then place it in deionized water at a 45° angle to the water surface and carry out a non-solvent-induced phase transformation process for 24 hours. After that, take it out to obtain a Ti-Fe3O4 blended modified polyethersulfone ultrafiltration membrane with catalytic function.

[0044] The transmission electron microscopy analysis of the Ti-Fe3O4 composite nanoparticles prepared in this embodiment is as follows: Figure 1 As shown, the lattice spacing of the nanoparticles is 0.2962 nm, which is larger than that of Fe3O4 nanoparticles (0.2747 nm). This indicates that Ti atoms have been successfully doped into the Fe3O4 lattice, and the Ti-Fe3O4 composite nanoparticles have been successfully prepared. The catalytic performance of the superparamagnetic Ti-Fe3O4 nanoparticles on sodium persulfate was tested according to the following steps:

[0045] (1) Take 200 ml of 20 mg / L methylene blue solution into an Erlenmeyer flask and test the initial absorbance;

[0046] (2) Add 0.2g of Ti-Fe3O4 nanoparticles to the conical flask to make the catalyst concentration 1g / L;

[0047] (3) Add 1 mL, 2 mL, 4 mL, 6 mL and 8 mL of 10 mM sodium persulfate solution to the conical flask to make the sodium persulfate concentrations 0.05 mM, 0.1 mM, 0.2 mM, 0.3 mM and 0.4 mM respectively.

[0048] (4) Samples were taken at 1 min, 2 min, 3 min, 5 min and 10 min, and then samples were taken every 10 min for a total reaction time of 1 hour to test the catalytic degradation effect.

[0049] The concentration of methylene blue was measured using a UV spectrophotometer, and the absorbance change at 664 nm was analyzed. The results are as follows: Figure 2 As shown, the removal rate of methylene blue gradually increased with the increase of sodium persulfate oxidant. When the concentration of sodium persulfate was 0.4 mM, the removal rate of methylene blue was 94%. Methylene blue could be degraded within 1 minute regardless of the concentration of oxidant added, indicating that the Ti-Fe3O4 nanocatalyst has good catalytic activity.

[0050] The surface EDS energy spectrum of the magnetic field-induced magnetic Ti-Fe3O4 blend-modified polyethersulfone ultrafiltration membrane in this embodiment is shown in the figure below. Figure 3 As shown, a large number of Fe and Ti elements were found on the membrane surface, indicating that the magnetic field induces the nanoparticles to migrate directionally and accumulate on the membrane surface.

[0051] The pure water flux and HA rejection rate of the magnetic field-induced magnetic Ti-Fe3O4 blend modified photoresponsive polyethersulfone ultrafiltration membrane in this embodiment were tested using a Millipore UFSC40001 ultrafiltration cup. Membrane flux and rejection performance were tested using dead-end filtration; the modified membrane's pure water flux was 608.03 L / m³. 2 •h, the retention rate of HA is 62.3%.

[0052] Example 2:

[0053] The preparation method of Ti-doped iron(III) oxide composite nanoparticle blend modified catalytic polyethersulfone ultrafiltration membrane in this embodiment is carried out according to the following steps: (1) Preparation of superparamagnetic Fe3O4 nanoparticles: 11.68g FeCl3·6H2O and 4.3g FeCl2·4H2O were dissolved in 300ml deionized water, the solution was transferred to a three-necked flask, ultrasonically dispersed, stirred and heated to 85℃. NH3·H2O was added to the solvent to adjust the pH to 10, and the reaction was carried out for 0.5h. After cooling to room temperature, the product was washed three times with deionized water and anhydrous ethanol, respectively, and dried in a vacuum drying oven at 80℃. The product was then ground to obtain superparamagnetic Fe3O4 nanoparticles.

[0054] (2) Preparation of Ti-Fe3O4 composite catalyst: 5g of superparamagnetic Fe3O4 nanoparticles were dispersed in 500mL of a mixed solution and ultrasonically dispersed. Then, 50mL of tetrabutyl titanate and 24mL of concentrated sulfuric acid were added, and the mixture was stirred vigorously for 60min. The precipitate was washed three times with deionized water and three times with anhydrous ethanol. The product was dried in a vacuum drying oven at 40℃. Finally, the dried product was calcined in a muffle furnace at 600℃ for 5h and ground to obtain superparamagnetic Ti-Fe3O4 nanoparticles. The mixed solution was composed of 200mL of anhydrous ethanol and 300mL of acetic acid.

[0055] (3) Add Ti-Fe3O4 nanoparticles to N,N-dimethylacetamide, then add polyvinylpyrrolidone and polyethersulfone resin, stir for 8 hours to obtain casting solution, wherein Ti-Fe3O4 nanoparticles are 0.45wt%, N,N-dimethylacetamide is 81.55wt%, polyvinylpyrrolidone is 3wt%, and polyethersulfone resin is 15wt%.

[0056] (4) Place the casting solution in a vacuum for 4 hours to allow it to stand and degas. Then, take a glass plate as a support and apply the casting solution evenly to the glass plate.

[0057] (5) Place the glass plate perpendicular to the magnetic field and leave it in the magnetic field for 30 seconds. Then place it in deionized water at a 45° angle to the water surface and carry out a non-solvent-induced phase transformation process for 24 hours. After that, take it out to obtain a Ti-Fe3O4 blended modified polyethersulfone ultrafiltration membrane with catalytic function.

[0058] The test method for pure water flux and retention performance in this embodiment is the same as in Embodiment 1. In this embodiment, the pure water flux is 651.244 L / m³. 2 •h, the retention rate of HA is 57.5%.

[0059] Example 3:

[0060] Unlike Example 1, the mass fraction of Ti-Fe3O4 nanoparticles added in step (3) is 0, 0.15wt%, 0.30wt%, 0.45wt%, 0.60wt%, and 0.75wt%, while the rest is the same as in Example 1.

[0061] The testing methods for pure water flux and retention performance in this embodiment are the same as in Embodiment 1. Figure 4 The pure water flux of the modified membrane is shown under different nanoparticle addition levels. Figure 4 It can be seen that the pure water flux of the membrane without nanoparticles is only 530.12 L / m. 2 •h, after adding nanoparticles, the pure water flux is 600L / m 2Above h, some can reach 700L / m 2 The result shows that adding a certain amount of nanoparticles can promote the pure water flux of the membrane. After adding nanoparticles, the pure water flux of the composite membrane increases, mainly because the membrane surface is more hydrophilic, which reduces the energy barrier for water to pass through the membrane.

[0062] Example 4:

[0063] Unlike Example 1, the nanoparticles added in step (3) were 0 wt%, 0.45 wt%, and 0.75 wt%, resulting in three membranes labeled M0, M3, and M5, respectively. The antifouling properties of the three membranes were tested in this example. The antifouling performance of the magnetically induced magnetic Ti-Fe3O4 blend-modified polyethersulfone ultrafiltration membrane in this example was tested using a Millipore UFSC40001 ultrafiltration cup. The specific steps are as follows:

[0064] (1) Driven by a constant pressure of 0.1 MPa, filter pure water for 30 min using cross-flow filtration mode, then filter a 20 mg / L BSA solution containing 0.1 mM PDS for 30 min. After filtration, backwash the membrane for 10 min. This is the first cycle.

[0065] (2) Filter pure water for 30 min, filter a 20 mg / L BSA solution containing 0.1 mM PDS for 30 min, and backwash the membrane for 10 min after filtration. This is the second cycle.

[0066] (3) Filter pure water for 30 min, filter a 20 mg / L BSA solution containing 0.1 mM PDS for 30 min, and backwash the membrane for 10 min after filtration. This is the third cycle.

[0067] The specific flux changes of the three types of membranes were examined at different time periods. Figure 5 The composite membrane with 0.75 wt% nanoparticles added exhibited good antifouling performance, with a specific flux of 0.69 after three cycles. The composite membrane without added nanoparticles showed weaker antifouling ability, with a specific flux of 0.41 after three cycles. This indicates that the composite membrane has a good catalytic oxidation effect during the filtration of pollutants, oxidizing and degrading pollutants during the filtration process, thereby reducing membrane fouling.

Claims

1. A method for preparing a Ti-doped iron oxide composite nanoparticle blend-modified catalytic polyethersulfone ultrafiltration membrane, characterized in that... This method is performed in the following steps: I. Preparation of superparamagnetic Fe3O4 nanoparticles: FeCl3·6H2O and FeCl2·4H2O were added to deionized water and ultrasonically dispersed at room temperature for 10-30 min to obtain mixed solution A; then, under nitrogen protection, the mixture was heated in a water bath, and NH3·H2O was added dropwise to mixed solution A until pH>10 to obtain precipitate A; precipitate A was first washed with deionized water, then washed with anhydrous ethanol, and then vacuum dried at 60-90℃ for 5-12 h, and then ground to obtain superparamagnetic Fe3O4 nanoparticles; II. Preparation of Ti-Fe3O4 composite catalyst: Superparamagnetic Fe3O4 nanoparticles were dispersed in mixed solution B, then tetrabutyl titanate was added, followed by concentrated sulfuric acid. The mixture was stirred for 60 min to obtain precipitate B. Precipitate B was first washed with deionized water, then washed with anhydrous ethanol, then vacuum dried at 40-60℃, and then calcined at 300-900℃. The mixture was then ground to obtain superparamagnetic Ti-Fe3O4 composite nanoparticles. Mixed solution B was composed of anhydrous ethanol and acetic acid. The molar ratio of Fe3O4 nanoparticles to tetrabutyl titanate was 1:1 to 1:20, and the molar ratio of tetrabutyl titanate to concentrated sulfuric acid was 1:1 to 1:

10.

3. Ultrasonically disperse the superparamagnetic Ti-Fe3O4 composite nanoparticles into a solvent, then add the pore-forming agent and polymer to the dispersion in sequence, and stir for 8-20 hours to form a casting solution; 4. The casting solution is placed under vacuum for degassing treatment, and then the casting solution is coated onto the support. A magnetic field is applied perpendicular to the support, and the mixture is left to stand in the magnetic field for 15~120s. Then the support 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, and a Ti-Fe3O4 blend-modified polyethersulfone ultrafiltration membrane with catalytic function is obtained.

2. The method for preparing a Ti-doped iron oxide composite nanoparticle blend-modified catalytic polyethersulfone ultrafiltration membrane according to claim 1, characterized in that, The mass ratio of FeCl3·6H2O to FeCl2·4H2O is 1:1 to 3:

1.

3. The method for preparing a Ti-doped iron oxide composite nanoparticle blend-modified catalytic polyethersulfone ultrafiltration membrane according to claim 1, characterized in that, The volume ratio of anhydrous ethanol to acetic acid in mixed solution B is 1:1 to 1:

5.

4. The method for preparing a Ti-doped iron tetroxide composite nanoparticle blend-modified catalytic polyethersulfone ultrafiltration membrane according to claim 1, characterized in that, The solvent mentioned in step three refers to a mixture of one or more of N-methylpyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, and dimethyl sulfoxide in any proportion.

5. The method for preparing a Ti-doped iron oxide composite nanoparticle blend-modified catalytic polyethersulfone ultrafiltration membrane according to claim 1, characterized in that, The polymer is polyvinylidene fluoride, polytetrafluoroethylene, polysulfone, or cellulose acetate.

6. The method for preparing a Ti-doped iron oxide composite nanoparticle blend-modified catalytic polyethersulfone ultrafiltration membrane according to claim 1, characterized in that, The pore-forming agent refers to a mixture of one or more of the following: polyvinylpyrrolidone, polyethylene glycol, oxalic acid, ethylene glycol, glycerin, lithium chloride, and lithium perchlorate, mixed in any proportion.

7. The method for preparing a Ti-doped iron oxide composite nanoparticle blend-modified catalytic polyethersulfone ultrafiltration membrane according to claim 1, characterized in that, In step four, the coating speed is 20~200 mm·s. -1 The coating thickness is 100~300μm.

8. The method for preparing a Ti-doped iron tetroxide composite nanoparticle blend-modified catalytic polyethersulfone ultrafiltration membrane according to claim 1, characterized in that, The strength of the magnetic field applied in step four is 0.001~1T.

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