A hydrophilic Fe-Vo-titania-PES self-cleaning composite membrane based on in-situ blending, a preparation method and application thereof

Abstract

This invention discloses a hydrophilic Fe-Vo-titanium dioxide-PES self-cleaning composite membrane based on in-situ blending, its preparation method, and its application, comprising the following steps: firstly, titanate nanotubes are prepared by hydrothermal method, and then anatase phase titanium dioxide (Vo-TiO2) containing bulk oxygen vacancies is obtained by high-temperature calcination. 2 Furthermore, Fe-modified titanium dioxide powder containing oxygen vacancies (Fe-Vo-TiO) was prepared using a simple impregnation method. 2 Hydrophilic Fe-Vo-TiO₂ was prepared using the phase inversion method. 2 -PES composite membrane. Tests on pure water flux, bovine serum albumin (BSA) rejection rate, and water contact angle demonstrated that the optimal membrane is Fe-Vo-TiO₂. 2 -PES-0.04 exhibits optimal hydrophilicity with a water flux of 222.6 L·m. ‑2 ·h ‑1 The BSA rejection rate reached 93%. Through photocatalytic-Fenton dynamic filtration degradation experiments of norfloxacin (NOR), the results showed that the prepared composite membrane achieved a NOR removal efficiency of 80%, and still maintained 75% after 8 cycles, demonstrating the excellent cycle stability of the composite membrane and solving the problems of difficult recovery of powdered catalysts and easy loss of active components.

Description

A hydrophilic Fe-Vo-titanium dioxide-PES self-cleaning composite membrane based on in-situ blending, its preparation method and application Technical Field

[0001] This invention belongs to the field of advanced oxidation technology, specifically relating to a hydrophilic Fe-Vo-titanium dioxide-PES self-cleaning composite membrane based on in-situ blending, its preparation method, and its application. Background Technology

[0002] With social development and advancements in medical technology, antibiotics are being produced and used on a large scale, entering natural aquatic environments through various pathways, posing a serious challenge to water resource security. Antibiotics have highly complex structures, and most cannot be naturally degraded; the long-term ecosystem risks caused by their accumulation cannot be ignored. Advanced oxidation processes (AOPs) are a promising method for removing organic pollutants from water. This technology is based on in-situ generation of highly reactive oxygen species (ROS), which can convert pollutants into smaller molecules or even completely mineralize them into water and carbon dioxide. Although AOPs exhibit excellent activity in antibiotic degradation, various limitations remain in practical applications. Currently, combining multiple advanced oxidation technologies to synergistically treat antibiotics in natural aquatic environments has become one of the effective strategies for addressing global antibiotic resistance and water purification. Among these, Fenton oxidation technology has advantages such as simple operation, mild conditions, and environmental friendliness, but... 2+ Slow regeneration is the rate-limiting step in the Fenton reaction. Combining photocatalysis with Fenton oxidation technology can, through synergistic effects, accelerate the Fe regeneration process in the Fenton reaction. 3+ / Fe 2+ The poor cycle stability and difficulty in separation and recovery of powdered catalysts are key problems faced in practical applications. Membrane separation technology has the characteristics of high efficiency, flexibility, and low energy consumption. Immobilizing the catalyst in a macroscopic membrane can reduce the loss of powdered catalyst. In addition, the catalytic material can effectively remove contaminants on the membrane surface, improve the flux recovery rate of the microporous membrane, and thus achieve a self-purification effect, reducing the amount of reagents used in traditional chemical cleaning processes and avoiding damage to the membrane structure. Therefore, designing a combined technology integrating multiple advanced oxidation technologies is of great significance for the current treatment of antibiotic wastewater. Summary of the Invention

[0003] To address the shortcomings of the existing technology, the present invention aims to provide a self-cleaning composite membrane based on in-situ blending of hydrophilic Fe-Vo-titanium dioxide-PES (hereinafter referred to as Fe-Vo-TiO2-PES), its preparation method, and its application.

[0004] This invention uses Fe-Vo-TiO2 powdered photocatalyst as the active component and PES porous membrane as the substrate to prepare an Fe-Vo-TiO2-PES membrane. By adding a small amount of hydrogen peroxide to the degradation reaction, a photocatalytic-Fenton system is constructed, generating a large number of reactive oxygen species such as hydroxyl radicals and superoxide radicals, achieving efficient oxidative degradation of norfloxacin antibiotics. Under optimized experimental conditions (catalyst concentration of 0.1 g / L, initial pH of 7, and H2O2 concentration of 5 mM), the photo-Fenton degradation method constructed in this invention can efficiently degrade organic pollutants. The composite membrane with the best performance shows an 82% removal rate of norfloxacin after 120 min of illumination. The prepared hydrophilic composite membrane exhibits excellent cycle stability and self-cleaning properties, with a flux recovery rate of 80%. This method broadens the applicable initial pH range of photo-Fenton technology, improves the iron species cycling process, and solves problems such as difficult recovery of powdered catalysts and easy loss of active components, thus having wider applicability to organic wastewater degradation.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for preparing a hydrophilic Fe-Vo-TiO2-PES self-cleaning composite membrane based on in-situ blending includes the following steps:

[0007] (1) Nanotube titanic acid was prepared by hydrothermal method; nanotube titanic acid was calcined to obtain anatase phase titanium dioxide containing bulk oxygen vacancies; anatase phase titanium dioxide was dispersed in deionized water, iron salt was added, pH was adjusted to acidic, stirred at 90-100℃ for 1-2 h, centrifuged, washed with solid water and dried to obtain Fe-Vo-TiO2;

[0008] (2) Add Fe-Vo-TiO2 to a polar solvent and disperse it evenly by ultrasonication at room temperature. Then add ground polyethersulfone (PES) powder and polyvinylpyrrolidone (PVP) powder and stir mechanically at 60-90℃ for 5-8 h to form a homogeneous casting solution. Then place it in an oven to stand. At room temperature, pour the casting solution after standing in the oven onto a flat, dry and clean glass plate. Adjust the thickness of the scraper and push the scraper at a uniform speed. After standing in the air for 10-30 s, immerse the glass plate in pure water to separate the phases and form a film. Thoroughly clean the film surface with ultrapure water to remove residual solvent and store it in ultrapure water for later use.

[0009] Further, in step (1), the iron salt is at least one of ferric nitrate and ferric chloride; the mass fraction of Fe is 0.1% to 7% based on the total amount of titanium dioxide and iron salt.

[0010] Furthermore, in step (1), adjusting the pH to acidic means adjusting the pH to 2-3.

[0011] Further, in step (2), the solvent added is N,N-dimethylacetamide (DMAC), the mass fraction of polyethersulfone in the solution is 15~20%, the mass ratio of Fe-Vo-TiO2 to polyethersulfone is 0.02~0.08, the mass ratio of polyethersulfone to polyvinylpyrrolidone is 2~5:1, the water bath temperature is 60-90℃, the oven settling temperature is 50-90℃, and the scraper thickness is 100-200μm.

[0012] This invention provides a hydrophilic Fe-Vo-TiO2-PES self-cleaning composite membrane based on in-situ blending prepared by the above method.

[0013] This invention also provides the application of the above-mentioned hydrophilic Fe-Vo-TiO2-PES self-cleaning composite membrane in the catalytic degradation of norfloxacin or methylene blue. The specific steps are as follows:

[0014] In a low-pressure flat-sheet membrane device, a composite membrane is installed and adsorbed in the dark for 30 minutes. Then, a 300 W xenon lamp is used as the light source for top irradiation. A photocatalytic-Fenton system is formed with or without added H2O2.

[0015] Specifically, in the above steps, the membrane thickness is 150 μm to 200 μm, the concentration of norfloxacin or methylene blue solution is 5-20 mg / L, the H2O2 concentration is 2.5-25 mM, the pH range of the reaction is 3-12, and the effective membrane area is 15.89 cm². 2 .

[0016] This invention utilizes Fe-Vo-TiO2 photocatalyst material as the active component and PES as the membrane matrix to construct a porous TiO2-based photocatalytic-Fenton composite membrane system for antibiotic degradation, optimizing degradation conditions and improving degradation efficiency and cycle stability. The Fe species in the photo-Fenton catalyst prepared in this invention provide a good photogenerated electron transport pathway, making it suitable for a wide pH range. Furthermore, catalyst immobilization achieves good reusability of the powder catalyst, significantly reducing recycling costs and extending the service life of the composite membrane.

[0017] The present invention has the following beneficial effects:

[0018] This invention utilizes a TiO2-based self-cleaning ultrafiltration membrane to degrade pollutants, addressing the low visible light utilization rate of TiO2 and the Fenton reaction of Fe. 2+To address the issues of slow regeneration and easy deactivation of active components in powdered catalysts, a hydrophilic composite ultrafiltration membrane is prepared by combining photocatalysis-Fenton reaction with membrane filtration technology to immobilize the catalyst. This effectively reduces iron loss during the photocatalysis-Fenton process, overcoming the application bottlenecks of traditional powdered catalysts, such as difficult separation and high recovery costs, and improving the material's cycle stability. Simultaneously, the catalyst and hydrogen peroxide can effectively form a photocatalysis-Fenton system. The reactive oxygen species such as hydroxyl radicals and superoxide radicals generated under light irradiation endow the composite membrane with a certain degree of self-cleaning ability. This technology has a simple preparation process and mild preparation conditions, making it widely applicable in the field of wastewater treatment. Attached Figure Description

[0019] Figure 1 is a flowchart of composite membrane preparation and a schematic diagram of a low-pressure flat sheet membrane device;

[0020] Figure 2 shows the experimental performance of photocatalytic Fenton degradation of norfloxacin in the samples obtained in Example 1 and Example 6;

[0021] Figure 3 shows a scanning electron microscope image of the sample obtained in Example 3;

[0022] Figure 4. Atomic force microscope image of the sample obtained in Example 3;

[0023] Figure 5 shows the X-ray powder diffraction pattern and infrared spectrum of the samples obtained in Examples 3 and 7;

[0024] Figure 6 shows the ultrafiltration performance results and contact angle test results of the composite membranes obtained in steps 3 and 7.

[0025] Figure 7 shows the experimental performance and cycle test results of the composite membranes obtained in steps 3 and 7 for photocatalytic Fenton degradation of norfloxacin.

[0026] Figure 8 shows the self-cleaning test results of the composite membrane obtained in Example 3. Detailed Implementation

[0027] The present invention will be further described in detail below with reference to specific examples, but the scope of protection of the present invention is not limited thereto.

[0028] Example 1

[0029] A method for preparing Fe-Vo-TiO2 powder photocatalyst, comprising the following steps:

[0030] (1) Weigh 3 g of commercial titanium dioxide P25 and add it to 300 mL of 10 mol / L sodium hydroxide aqueous solution. Stir magnetically for 2 h to disperse it evenly. Pour the mixture evenly into a 100 mL high-pressure reactor and keep it at 120℃ for 24 h. Wash with water until neutral, soak in 0.1 M hydrochloric acid for 12 h, and then wash away excess Cl with deionized water. -The nanotube titanate was dried under vacuum at 60℃ for 24 h to obtain a white powder, denoted as NTA. 1 g of NTA was weighed and placed in a crucible, then placed in a tubular furnace and heated at 10℃ for 1 min. -1 The anatase phase titanium dioxide containing bulk oxygen vacancies was calcined at 400℃ for 2 h to obtain a white powder, denoted as Vo-TiO2.

[0031] (2) Weigh 0.1 g of the product obtained in step (1) and disperse it in 10 mL of deionized water. Then weigh 0.0036 g of Fe(NO3)3・9H2O and add it to the suspension. Adjust the pH of the mixture to 2 with 8 mol / L nitric acid. After ultrasonic dispersion for 30 min, stir in an oil bath at 90℃ for 1 h, centrifuge, wash the solid three times with water to obtain a pale yellow product, dry at 60℃ for at least 12 h, grind to obtain a yellow powder, denoted as Fe-Vo-TiO2.

[0032] Example 2

[0033] A method for preparing Fe-Vo-TiO2 powder photocatalyst, comprising the following steps:

[0034] (1) Weigh 3 g of commercial titanium dioxide P25 and add it to 300 mL of 10 mol / L sodium hydroxide aqueous solution. Stir magnetically for 2 h to disperse it evenly. Pour the mixture evenly into a 100 mL high-pressure reactor and keep it at 120℃ for 24 h. Wash with water until neutral, soak in 0.1 M hydrochloric acid for 12 h, and then wash away excess Cl with deionized water. - The nanotube titanate was dried under vacuum at 60℃ for 24 h to obtain a white powder, denoted as NTA. 1 g of NTA was weighed and placed in a crucible, then placed in a tubular furnace and heated at 10℃ for 1 min. -1 The anatase phase titanium dioxide containing bulk oxygen vacancies was calcined at 400℃ for 2 h to obtain a white powder, denoted as Vo-TiO2.

[0035] (2) Weigh 0.1 g of the product obtained in step (1) and disperse it in 10 mL of deionized water. Then weigh 0.0036 g of FeCl3・6H2O and add it to the suspension. Adjust the pH of the mixture to 2 with 12 mol / L hydrochloric acid. After ultrasonic dispersion for 30 min, stir in an oil bath at 90℃ for 1 h, centrifuge, wash the solid three times with water to obtain a pale yellow product, dry at 60℃ for at least 12 h, grind to obtain a yellow powder, denoted as Fe-Vo-TiO2.

[0036] Example 3

[0037] A method for preparing a Fe-Vo-TiO2-PES self-cleaning composite membrane is shown in Figure 1(a), and the steps are as follows:

[0038] (1) Weigh 0.18 g of Fe-Vo-TiO2 and add it to 19 g of DMAc solvent. Disperse it by ultrasonication (ultrasonic power of 600W) at room temperature for 30 min to form a uniformly dispersed suspension and prevent the catalyst particles from precipitating and agglomerating.

[0039] (2) Weigh 4.5 g of PES (model E6020P, BASF, Germany, the same below) powder and 1.5 g of PVP (M W =10000 (the same below) powder is fully ground (manual grinding for 30 minutes) and added to the above suspension. The PES powder is mechanically stirred for 5 hours in a 60°C water bath to fully dissolve the PES powder and form a homogeneous casting solution. The casting solution is then placed in a 60°C oven and left to stand for 3 hours to mature and degas.

[0040] (3) At room temperature, slowly and evenly pour the casting solution in a long strip onto a flat, dry, and clean glass plate. Adjust the thickness of the scraper to 150 μm, push the scraper at a uniform speed, and let it stand in the air for 10 s. Then immerse the glass plate in pure water to allow it to separate into phases and form a film. Thoroughly wash the film surface with ultrapure water to remove residual solvent. Then store it in ultrapure water for later use.

[0041] The preparation process of the PES membrane for comparison is as follows:

[0042] (1) Weigh 4.5 g of PES powder and 1.5 g of PVP powder, grind them manually for 30 min, and add them to 19 g of DMAc solvent. Stir mechanically for 5 h in a 60℃ water bath to fully dissolve the PES powder and form a homogeneous casting solution. Then place the casting solution in a 60℃ oven and let it stand for 3 h to mature and degas.

[0043] (2) At room temperature, slowly and evenly pour the casting solution in a long strip onto a flat, dry, and clean glass plate. Adjust the thickness of the scraper to 150 μm, push the scraper at a uniform speed, and let it stand in the air for 10 s. Then immerse the glass plate in pure water to allow it to separate into phases and form a film. Thoroughly wash the film surface with ultrapure water to remove residual solvent. Then store it in ultrapure water for later use.

[0044] Example 4

[0045] (1) Weigh 0.18 g of Fe-Vo-TiO2 and add it to 19 g of DMAc solvent. Disperse it by ultrasonication (ultrasonic power of 600W) at room temperature for 30 min to form a uniformly dispersed suspension and prevent the catalyst particles from precipitating and agglomerating.

[0046] (2) Weigh 4.5 g of PES powder and 1.5 g of PVP powder, grind them manually for 30 min and add them to the above suspension. Stir mechanically for 5 h in an 80℃ water bath to fully dissolve the PES powder and form a homogeneous casting solution. Then place the casting solution in a 60℃ oven and let it stand for 3 h to mature and degas.

[0047] (3) At room temperature, slowly and evenly pour the casting solution in a long strip onto a flat, dry, and clean glass plate. Adjust the thickness of the scraper to 150 μm, push the scraper at a uniform speed, and let it stand in the air for 10 s. Then immerse the glass plate in pure water to allow it to separate into phases and form a film. Thoroughly wash the film surface with ultrapure water to remove residual solvent. Then store it in ultrapure water for later use.

[0048] Example 5

[0049] (1) Weigh 0.18 g of Fe-Vo-TiO2 and add it to 19 g of DMAc solvent. Disperse it by ultrasonication (ultrasonic power of 600W) at room temperature for 30 min to form a uniformly dispersed suspension and prevent the catalyst particles from precipitating and agglomerating.

[0050] (2) Weigh 4.5 g of PES powder and 1.5 g of PVP powder, grind them manually for 30 min and add them to the above suspension. Stir mechanically for 5 h in a 60℃ water bath to fully dissolve the PES powder and form a homogeneous casting solution. Then place the casting solution in a 60℃ oven and let it stand for 3 h to mature and degas.

[0051] (3) At room temperature, slowly and evenly pour the casting solution in a long strip onto a flat, dry, and clean glass plate. Adjust the thickness of the scraper to 200 μm, push the scraper at a uniform speed, and let it stand in the air for 10 s. Then immerse the glass plate in pure water to allow it to separate into phases and form a film. Thoroughly wash the film surface with ultrapure water to remove residual solvent. Then store it in ultrapure water for later use.

[0052] Example 6

[0053] The difference from Example 1 is that the amount of Fe(NO3)3・9H2O in step (2) was changed to 0.00072g, 0.0072g, and 0.0504g, and the resulting samples were named 0.1% Fe-Vo-TiO2, 1% Fe-Vo-TiO2, and 7% Fe-Vo-TiO2, respectively. The sample from Example 1 was recorded as 0.5% Fe-Vo-TiO2.

[0054] Figure 2 shows the photocatalytic-Fenton degradation performance of norfloxacin in the samples obtained in Examples 1 and 6. As can be seen from Figure 2, the degradation efficiency was improved after introducing Fe(NO3)3·9H2O. When the Fe content was greater than 0.5%, the degradation efficiency no longer increased. Furthermore, since excessive Fe may generate iron sludge during the reaction, leading to increased post-treatment costs, 0.5% was selected as the optimal Fe ratio for both high efficiency and environmental protection.

[0055] Example 7

[0056] The difference from Example 3 is that the amount of Fe-Vo-TiO2 in step (1) was changed to 0.09 g, 0.27 g, and 0.36 g. These were named Fe-Vo-TiO2-0.02, Fe-Vo-TiO2-0.06, and Fe-Vo-TiO2-0.08, respectively. The sample from Example 3 was designated Fe-Vo-TiO2-0.04.

[0057] The scanning electron microscope (SEM) image of the sample obtained in Example 3 is shown in Figure 3(ad). As can be seen from Figure 3(ab), the membrane surface has a uniformly distributed sponge-like pore structure. Due to the addition of the Fe-Vo-TiO2 nanocatalyst, the pore structure on the composite membrane surface gradually increases and enlarges, forming numerous uniform honeycomb-like macropores on the membrane surface. Figure 3(cd) is a cross-sectional SEM image of the membrane sample, showing that the composite membrane consists of a dense skin layer and finger-like macropore structures, exhibiting a typical asymmetric structure. Due to the addition of the catalyst, the top dense layer becomes thinner, which is more conducive to the membrane's permeability.

[0058] Figure 4 shows the atomic force microscopy image of the sample obtained in Example 3. The membrane surface has a large number of "valleys and peaks" structures. This rough surface structure can increase the effective area of ​​the membrane and improve the hydrophilicity and permeability of the membrane.

[0059] The X-ray powder diffraction patterns and infrared spectra of the samples obtained in Examples 3 and 7 are shown in Figure 5. As can be seen from Figure 5(a), the modified film with added Fe-Vo-TiO2 nanoparticles exhibits a new characteristic peak at 2θ = 25.3, corresponding to the (101) crystal plane of the anatase phase TiO2, confirming that the Fe-Vo-TiO2 nanoparticles have been successfully embedded into the PES film. From Figure 5(b), it can be observed that due to the addition of Fe-Vo-TiO2 nanoparticles, the composite film at 500 cm⁻¹... -1 New characteristic peaks appeared on both sides, consistent with the Ti-O-Ti characteristic peaks in the Fe-Vo-TiO2 powder sample, proving that the composite ultrafiltration membrane was successfully prepared in the experiment. The characteristic peaks observed in the figure are all characteristic peaks of functional groups in PES or Fe-Vo-TiO2 materials; no other new absorption peaks appeared, indicating that no other substances were introduced during the modification process.

[0060] Experimental Example 1

[0061] The smooth, bubble-free, and clean composite membranes obtained in Examples 3 and 7 were selected and placed in a low-pressure flat-panel membrane device, as shown in Figure 1(b). 500 mL of ultrapure water was poured into the material tank, the circulating solution volume was 1 L, and the effective membrane area was 15.89 cm². 2 The ultrafiltration performance of the membrane was tested, and the test data included: pure water flux and bovine serum albumin rejection rate. First, the membrane was pre-compacted with ultrapure water at a pressure of 0.1 MPa for 10 min to obtain a stable pure water flux; then, the volume of permeate was recorded, and the initial pure water flux (J0) of the ultrafiltration membrane was calculated by recording the volume V of permeate over 5 min.

[0062] J0=V / A·t

[0063] (J0 represents pure water flux, in L·m) -2 ·h -1 V represents the permeate volume in liters (L); A represents the effective filtration area of ​​the membrane in square meters (m²). 2 t represents the time required for the membrane to permeate through VL, in hours.

[0064] The membrane material was placed in the membrane tank, and the circulating solution was replaced with 500 mL of bovine serum albumin solution at a concentration of 10 mg / L. The solution was run at 0.1 MPa for 10 min. 3 mL of filtrate was collected at the outlet to test its absorbance. The concentration was then substituted into the standard curve, and the rejection rate was calculated using the following formula:

[0065] R = (1-C) p / C f ) × 100%

[0066] (R represents the rejection rate; C) p and C f (These represent the solute concentrations in the permeate and feed solutions, respectively.)

[0067] The ultrafiltration performance results of the composite membranes obtained in Examples 3 and 7 are shown in Figure 6(a). With Fe-V OAs the amount of TiO2 added increased, the pure water flux of the composite membrane showed a trend of first increasing and then decreasing. The contact angle test results of the composite membranes obtained in Examples 3 and 7 are shown in Figure 6(b). Generally, a water contact angle greater than 90° is considered hydrophobic, and less than 90° is considered hydrophilic; the smaller the contact angle, the better the hydrophilicity. The results show that all prepared composite membranes are hydrophilic ultrafiltration membranes, and the changes in contact angle are consistent with the ultrafiltration performance results. When the mass ratio of Fe-Vo-TiO2 to PES is 0.04, the composite membrane has the smallest contact angle, the best hydrophilicity, and the highest pure water flux of 222.6 L·m. -2 ·h -1 .

[0068] Experimental Example 2

[0069] The composite membranes obtained in Examples 3 and 7 were selected and placed in a low-pressure flat-sheet membrane device. 200 mL of the target pollutant norfloxacin (NOR) solution with a concentration of 10 mg / L was poured into the material tank. The system was operated at 0.1 MPa. After 30 min of dark adsorption, 20 μL of 30 wt% H₂O₂ was added, bringing the final H₂O₂ concentration in the system to 5 mM. The light source (a 300 W xenon lamp placed above the membrane tank, 10-20 cm from the reactor) was turned on, and timing began. Every 30 min, 3 mL of permeate was collected from the permeate outlet, and its absorbance was measured. The concentration was then calculated by substituting the absorbance into a standard curve.

[0070] The performance of the composite membranes obtained in Examples 3 and 7 in the photocatalytic-Fenton degradation system is shown in Figure 7. As shown in Figure 7(a), the composite membrane exhibits a higher degradation efficiency than the single PES membrane. Kinetic analysis of the degradation process is shown in Figure 7(b). The degradation process conforms to a first-order kinetic equation, where the degradation rate constant of the composite membrane obtained in Example 3 is 2.5 times that of the single PES membrane. Figure 7(c) demonstrates that the Fe-Vo-TiO2-PES-0.04 composite membrane has excellent reusability, reduces the loss of powdered catalyst, and has the advantage of low recycling cost.

[0071] Experimental Example 3

[0072] This invention designed an organic dye filtration experiment and a photocatalytic-Fenton catalytic oxidation experiment to dynamically describe the permeability changes of the composite membrane at different stages (pure water filtration, dye separation, photocatalytic-Fenton catalytic oxidation, and pure water filtration). The specific steps are as follows: The composite membrane is placed in a low-pressure flat-sheet membrane device, 500 mL of pure water is added, and the device is run at 0.1 MPa for 30 min, recording its pure water flux J0; then, the pure water is replaced with 500 mL of methylene blue solution (10 mg / L), and the device is run under the same conditions for 30 min; the fouled membrane is placed in 50 mL of water, and 5 μL of 30 wt% H2O2 is added, at which point the final concentration of H2O2 in the system is 5 mM. After irradiation for 30 min, its pure water flux is measured again, and the flux recovery rate is calculated.

[0073] Figure 8 shows the self-cleaning test results of the composite membrane obtained in Example 3. As shown in Figure 8(a), when filtering and separating a 10 mg / L methylene blue solution, the normalized permeability of the membrane decreased sharply. After placing the fouled composite membrane in 50 mL of pure water and adding 5 mM H2O2, and treating it under light irradiation for 30 min, its pure water flux was evaluated again, and its normalized permeability increased. After two cycles, the flux recovery rate of the composite membrane was 80%. Combined with the fact that the membrane after photocatalytic-Fenton cleaning still showed a clean surface in Figure 8(b), it indicates that the composite membrane has good antifouling performance.

[0074] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions conceived without any inventive effort should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A method for preparing a hydrophilic Fe-Vo-TiO2-PES self-cleaning composite membrane based on in-situ blending, characterized in that, The steps include: (1) preparing nanotube titanic acid by hydrothermal method; calcining nanotube titanic acid to obtain anatase phase titanium dioxide containing bulk oxygen vacancies; dispersing anatase phase titanium dioxide in deionized water, adding iron salt, adjusting pH to 2-3, stirring at 90-100℃ for 1-2 h, centrifuging, washing with solid water, and drying to obtain Fe-Vo-TiO2; the iron salt is at least one of ferric nitrate and ferric chloride; the mass fraction of Fe is 0.1%~7% based on the total amount of titanium dioxide and iron salt; (2) adding Fe-Vo-TiO2 to a polar solvent, ultrasonically dispersing it evenly at room temperature, adding ground polyethersulfone (PES) powder and polyvinylpyrrolidone (PVP) powder, and mechanically stirring at 60-90℃ for 5-8 hours. h, forming a homogeneous casting solution; then place it in an oven to stand at room temperature, pour the settled casting solution onto a flat, dry, and clean glass plate surface, adjust the doctor blade thickness, and push the doctor blade evenly. After standing in the air for 10-30 seconds, immerse the glass plate in pure water to allow it to separate into phases and form a film. Thoroughly wash the film surface with ultrapure water to remove residual solvent, and then store it in ultrapure water for later use. The polar solvent added is N,N-dimethylacetamide (DMAC), the mass fraction of polyethersulfone in the solution is 15-20%, the mass ratio of Fe-Vo-TiO2 to polyethersulfone is 0.02-0.08, and the mass ratio of polyethersulfone to polyvinylpyrrolidone is 2-5:

1.

2. The method for preparing the hydrophilic Fe-Vo-TiO2-PES self-cleaning composite membrane based on in-situ blending as described in claim 1, characterized in that: In step (2), the oven temperature is 50-90℃ and the scraper thickness is 100-200 μm.

3. The hydrophilic Fe-Vo-TiO2-PES self-cleaning composite membrane based on in-situ blending prepared by the preparation method of claim 1 or 2.

4. The application of the hydrophilic Fe-Vo-TiO2-PES self-cleaning composite membrane according to claim 3 in the catalytic degradation of norfloxacin or methylene blue.

5. The application according to claim 4, characterized in that, The thickness of the membrane is 150 μm to 200 μm, and the concentration of the norfloxacin or methylene blue solution is 5-20 mg / L.

6. The application according to claim 4, characterized in that, The experiment was conducted under one or more of the following conditions: (1) the concentration of added hydrogen peroxide was 0-25 mM; (2) the pH value was 3-12; and (3) a 300 W xenon lamp was used as the light source.

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