Preparation method and application of high-flux photocatalytic membrane constructed directionally through magnetic induction

Abstract

The invention relates to a preparation method and application of a high-flux photocatalytic membrane constructed directionally through magnetic induction, and the preparation method comprises the following steps: step 1, preparation of photocatalytic functional materials: respectively preparing Bi5O7I powder, Bi nano powder and Co3O4 nano powder; step 2, preparation of composite photocatalytic slurry: mixing Bi5O7I powder, Bi nanopowder and Co3O4 nanopowder according to a mass ratio of 5: 1: 2, adding ethanol and DMSO according to a volume ratio of 4: 1, and adding a film-forming carrier to form the catalytic slurry; step 3, magnetically induced migration and membrane construction: the catalytic slurry is placed in a vertical gradient magnetic field, the magnetic induction intensity gradient is 0.2 T / cm, and the magnetic Co3O4 particles and the composite clusters are migrated and gathered on the surface layer of the membrane; 4, directional freezing casting and film curing are conducted, directional freezing casting is conducted for 12 h at the temperature of-80 DEG C, and a longitudinal through hole channel is formed; and step 5, vacuum drying and film forming: drying at-60 DEG C under the vacuum pressure of less than or equal to 10Pa to obtain the complete flexible self-supporting film.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of photocatalytic membrane materials and membrane separation technology, in particular to a preparation method and application of a high-flux photocatalytic membrane constructed by magnetic induction and orientation, which is a high-porosity, low-resistance and high-flux Co3O4 / Bi5O7I / Bi composite photocatalytic membrane material constructed by magnetic induction and orientation freeze casting process, and is suitable for environmental protection fields such as wastewater treatment and water purification. BACKGROUND

[0002] The photocatalytic membrane technology has attracted wide attention due to its high efficiency in pollutant degradation and separation, but the traditional photocatalytic membrane has the following defects:

[0003] The catalyst is randomly distributed in the membrane matrix, which easily causes pore blockage;

[0004] The porosity is low and the water flux is small, which affects the treatment efficiency;

[0005] The membrane material structure is dense and the flow resistance is large, which is not conducive to large-scale application. In order to solve the above problems, it is urgent to develop a new type of photocatalytic membrane material with reasonable structure, synergistic function, excellent catalytic and separation performance. SUMMARY

[0006] In view of the defects of the prior art, the purpose of the present application is to provide a preparation method and application of a high-flux photocatalytic membrane constructed by magnetic induction and orientation, which combines magnetic response materials, directional freeze casting structure control technology and plasma synergistic photocatalytic mechanism, maintains the porosity and flux of the membrane, and improves the photocatalytic degradation performance, thereby breaking through the bottleneck problems of traditional photocatalytic membranes such as easy pore blockage and low flux.

[0007] The above invention purpose of the present application is realized by the following technical scheme:

[0008] A preparation method of a high-flux photocatalytic membrane constructed by magnetic induction and orientation, comprising the following steps:

[0009] Step 1, preparation of photocatalytic functional material, Bi5O7I powder, Bi nano powder and Co3O4 nano powder are prepared respectively;

[0010] Step 2, preparation of composite photocatalytic slurry, Bi5O7I powder, Bi nano powder and Co3O4 nano powder are mixed in a mass ratio of 5:1:2, ethanol and DMSO in a volume ratio of 4:1 are added, and a film forming carrier is added to form a catalytic slurry;

[0011] Step 3, magnetic induction migration and membrane construction, the catalytic slurry is placed in a vertical gradient magnetic field, the magnetic induction intensity gradient is 0.2T / cm, and the magnetic Co3O4 particles and composite clusters are migrated and aggregated on the surface layer of the membrane;

[0012] Step 4, directional freeze casting and film solidification, directional freeze casting at -80℃ for 12h to form longitudinal through channels;

[0013] Step 5, vacuum drying and film forming, drying treatment at -60℃ under vacuum pressure ≤10Pa to obtain a complete flexible self-supporting film.

[0014] As a further technical solution of the present application: in the step 1, the preparation method of the Bi5O7I powder comprises the following steps: weighing 10mmol Bi(NO3)3·5H2O and dissolving it in 40mL of 0.5M dilute nitric acid, after stirring completely, adding 5mmol KI, and continuously stirring for 30min;

[0015] The mixed solution is transferred to a 100mL polytetrafluoroethylene lined autoclave, and hydrothermal reaction is carried out at 180℃ for 24h. After cooling, centrifugation, alternating ethanol and water washing, and vacuum drying (60℃, 12h), yellow crystal Bi5O7I powder is obtained.

[0016] As a further technical solution of the present application: in the step 1, the preparation method of the Bi nano-powder comprises the following steps: weighing 1mmol Bi(NO3)3·5H2O and dissolving it in 30mL of ethylene glycol, adding 0.5g PVP, and stirring to form a transparent solution;

[0017] Drop 0.1M NaBH4 solution (15mL) into the above solution, and react at 80℃ for 4h to reduce metal Bi 0 Nanoparticles, centrifugation, washing, and vacuum drying at room temperature for 12h to obtain black Bi nano-powder.

[0018] As a further technical solution of the present application: in the step 1, the preparation method of the Co3O4 nano-powder comprises the following steps: weighing 2mmol Co(NO3)2·6H2O and dissolving it in 100mL of water, dropwise adding NaOH solution (1M) to adjust pH to 10, constant temperature stirring for 2h, and standing to mature to form cobalt hydroxide;

[0019] After centrifugation and washing, drying and calcining in air at 500℃ for 3h, Co3O4 nano-powder with excellent magnetic response is obtained.

[0020] As a further technical solution of the present application: in the step 2, the film forming carrier is polyvinyl alcohol or polyvinylidene fluoride, and the concentration is 6-8wt%.

[0021] As a further technical solution of the present application: in the step 3, the magnetic induction treatment time is 30min.

[0022] As a further technical solution of the application: the prepared photocatalytic membrane porosity is greater than or equal to 75%, the average pore size is 120nm, and the surface is rich in Co3O4 / Bi5O7I / Bi catalyst.

[0023] As a further technical solution of the application: the prepared photocatalytic membrane has a filtration flux of greater than or equal to 1300L·m -2 ·h -1 .

[0024] The application of the Co3O4 / Bi5O7I / Bi photocatalytic membrane prepared by the above-mentioned method of preparing a magnetic induction directional construction high-flux photocatalytic membrane in wastewater treatment.

[0025] In summary, the application has at least one of the following beneficial technical effects:

[0026] 1. The application discloses a method for preparing a magnetic induction directional construction high-flux photocatalytic membrane and application thereof, which comprises the following core content: composite material construction, using Co3O4 / Bi5O7I / Bi composite material as a photocatalytic component, wherein: Bi5O7I provides a wide spectrum response; metal Bi realizes surface plasmon resonance (SPR) enhancement; Co3O4 has magnetic response characteristics and serves as a cocatalyst. Magnetic induction directional migration, under the action of a magnetic field, directionally enriches the catalytic component containing magnetic Co3O4 on the surface of the membrane, avoids the catalyst from entering the interior of the membrane body, reduces the phenomenon of pore blockage, and improves the reaction interface efficiency. Directional freeze casting uses DMSO as a solvent and a pore-forming template, and adopts a directional freezing method to quickly generate large-size lattice-shaped pores, forms a highly ordered open pore structure, and greatly improves: porosity (up to 75%); water flux (up to 1350L / m 2 ·h, about 1.9 times that of a traditional ultrafiltration membrane); mass transfer rate and pollutant contact area. A high-activity region is formed on the surface of the catalytic membrane, and under visible light / near-infrared irradiation, the high-activity region realizes efficient degradation of organic pollutants in water through the synergistic effect of SPR and heterojunction.

[0027] 2. The application utilizes the synergistic strategy of magnetic induction directional migration and freeze template to realize precise regulation and functional integration of the photocatalytic membrane structure. The significant high flux, high catalysis, high stability and good recovery characteristics provide technical support for efficient treatment of high-concentration antibiotic wastewater and other refractory pollutants, and are suitable for constructing a photocatalytic membrane reactor, a flow photocatalytic system or a membrane coupling device and other engineering application scenarios, and have significant innovation and practical promotion value.

[0028] 3. The application discloses a preparation method and application of a Co3O4 / Bi5O7I / Bi photocatalytic film prepared through magnetic induction directional construction. -2 ·h -1 Under visible light / near-infrared irradiation for 2 hours, the degradation rate of tetracycline is greater than 99%, the performance degradation of 5 cycles is less than 2%, and the film can be magnetically separated and recovered. The film is suitable for high-concentration organic wastewater treatment. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 A flowchart of the method of the application.

[0030] Figure 2 An ultraviolet-visible diffuse reflectance spectrum of the Co3O4 / Bi5O7I / Bi photocatalyst in the application.

[0031] Figure 3 A flux performance comparison diagram of different catalyst films under constant pressure in the application.

[0032] Figure 4 A degradation performance comparison diagram of different catalyst films in the application.

[0033] Figure 5 A TC cycle performance test diagram of the Co3O4 / Bi5O7I / Bi film in the application.

[0034] Figure 6 A water flux cycle test diagram of the Co3O4 / Bi5O7I / Bi film in the application. DETAILED DESCRIPTION

[0035] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the drawings in the embodiments of the application; obviously, the described embodiments are only some of the embodiments of the application, rather than all the embodiments of the application, and all other embodiments obtained by a person of ordinary skill in the art without creative labor on the basis of the embodiments in the application belong to the protection scope of the application.

[0036] In the description of the application, it should be noted that the terms "upper", "lower", "inner", "outer", "top / bottom end" and the like indicate the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the application. In addition, the terms "first", "second" are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0037] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "provided with", "sleeved / connected", "connected" and the like should be understood broadly, for example, "connected" can be fixedly connected, or detachably connected, or integrally connected; can be mechanically connected, or electrically connected; can be directly connected, or indirectly connected through an intermediate medium, or can be connected inside two elements. For those skilled in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0038] Embodiment one:

[0039] Referring to Figure 1 A preparation method of a high-flux photocatalytic film prepared by magnetic induction directional construction is disclosed, comprising the following steps:

[0040] Step 1: Preparation of photocatalytic functional material:

[0041] Take 10 mmol Bi(NO3)3·5H2O (about 4.85 g) and dissolve it in 40 mL of 0.5M dilute nitric acid. After stirring completely, add 5 mmol KI (about 0.83 g) and continue stirring for 30 min. Transfer the mixed solution to a 100 mL polytetrafluoroethylene-lined autoclave, and hydrothermal reaction at 180℃ for 24 h. After cooling, centrifugation, alternating ethanol and water washing, and vacuum drying (60℃, 12 h), yellow crystal Bi5O7I powder is obtained.

[0042] Synthesis of Bi nanoparticles: Take 1 mmol Bi(NO3)3·5H2O (0.485 g) and dissolve it in 30 mL of ethylene glycol. Add 0.5 g of PVP and stir to form a transparent solution. Add 0.1M NaBH4 solution (15 mL) to the above solution and react at 80℃ for 4 h to reduce the metal Bi 0 nanoparticles. After centrifugation and washing, vacuum drying at room temperature for 12 h, black Bi nanopowder is obtained.

[0043] Synthesis of magnetic Co3O4 particles: Take 2 mmol Co(NO3)2·6H2O (0.582 g) and dissolve it in 100 mL of water. Add NaOH solution (1M) to adjust the pH to 10, and stir at constant temperature for 2 h. Let it stand and mature to form cobalt hydroxide. After centrifugation and washing of the precipitate, dry and calcine at 500℃ in air for 3 h to obtain Co3O4 nanopowder with excellent magnetic response.

[0044] Step 2: Preparation of composite photocatalytic slurry:

[0045] Bi5O7I, Bi nanoparticles and Co3O4 were mixed in a mass ratio of 5:1:2 (e.g., Bi5O7I 1.0 g, Bi 0.2 g, Co3O4 0.4 g), a mixed solvent of ethanol and DMSO (volume ratio 4:1, 10 mL) was added, an appropriate amount of polyvinyl alcohol (PVA) or polyvinylidene fluoride (PVDF) was added as a film carrier (concentration 6-8 wt%), and magnetic stirring was performed for 4 hours to obtain a stable dispersed Co3O4 / Bi5O7I / Bi composite catalytic slurry with moderate viscosity and good film coating suitability.

[0046] Step 3: magnetic induction migration and film construction process:

[0047] The above-mentioned catalytic slurry was slowly injected into a horizontal flat mold and placed in a self-made vertical gradient magnetic field environment (a permanent magnetic field with a lower intensity at the top and a higher intensity at the bottom, with a magnetic induction intensity gradient of 0.2 T / cm). Under the driving force of the magnetic field, the magnetic Co3O4 particles and composite clusters migrated and aggregated on the surface layer of the film, realizing the directional enrichment of particles. The entire magnetic field treatment lasted for 30 min, ensuring the formation of a structure-oriented surface enrichment region, which laid the foundation for subsequent freeze film formation.

[0048] Step 4: directional freeze casting and film solidification:

[0049] After the completion of magnetic induction, the slurry mold was quickly transferred to a low-temperature freezing plate (controlled at a temperature below -80℃), and directional freeze casting was performed using a bottom cooling method. Ice crystals grew in the vertical direction, inducing the directional formation of pores and driving the migration of solutes in the slurry to the ice crystal interface. After 12 h of freezing, the preliminary solidification structure was completed. This step helps to construct vertically penetrating open channel structures, greatly improving the water flux and mass transfer efficiency of the film.

[0050] Step 5: vacuum drying and film formation:

[0051] The frozen film block was subjected to sublimation drying treatment in a vacuum freeze dryer (-60℃, vacuum <10 Pa, 24 h) to remove the frozen solvent and retain the ice crystal-induced porous structure. Finally, a complete and flexible self-supporting film was obtained, with a thickness of about 200-300 μm, good mechanical strength, photocatalytic activity and liquid flux. The film can maintain structural stability in a water environment and is suitable for dynamic photocatalytic membrane reactor systems.

[0052] The present application proposes a magnetic induction directional construction photocatalytic membrane, which combines magnetic response materials, directional freeze casting structure control technology and plasma synergistic photocatalytic mechanism, while maintaining the porosity and flux of the membrane, it improves the photocatalytic degradation performance, and breaks through the bottleneck problems of traditional photocatalytic membranes such as easy plugging and low flux.

[0053] The application comprises the following core content: composite material construction, using Co3O4 / Bi5O7I / Bi composite material as a photocatalytic component, wherein: Bi5O7I provides a wide spectrum response; metal Bi realizes surface plasmon resonance (SPR) enhancement; Co3O4 has magnetic response characteristics and acts as a cocatalyst. Magnetic induction directional migration, under the action of a magnetic field, causes the catalytic component containing magnetic Co3O4 to be directionally enriched to the membrane surface region, avoids the catalyst from entering the membrane body, reduces the phenomenon of pore blockage, and improves the reaction interface efficiency. Directional freeze casting uses DMSO as a solvent and a pore-forming template, and uses a directional freezing method to quickly generate large-size lattice-shaped pores, forms a highly ordered open pore structure, and greatly improves: porosity (up to 75%); water flux (up to 1350 L / m 2 ·h, about 1.9 times that of a traditional ultrafiltration membrane); mass transfer rate and pollutant contact area. The catalytic membrane surface forms a high-activity region, and under visible / near-infrared irradiation, through the synergistic effect of SPR and heterojunction, efficient degradation of organic pollutants in water is realized.

[0054] Reference Figure 2 Compared with traditional photocatalysts that only respond to ultraviolet light or visible light, the ultraviolet-visible diffuse reflectance spectrum of the Co3O4 / Bi5O7I / Bi photocatalyst shows that the Co3O4 / Bi5O7I / Bi can respond to light in the near-infrared region.

[0055] Example Two

[0056] Application of the Co3O4 / Bi5O7I / Bi photocatalytic membrane prepared by the preparation method of a magnetic induction directional construction high-flux photocatalytic membrane in Example One in wastewater treatment.

[0057] Experimental Example

[0058] In order to verify the performance improvement of the magnetic induction freeze construction strategy in the application on the photocatalytic membrane, first, the membrane material structure performance test was carried out. The prepared Co3O4 / Bi5O7I / Bi composite catalytic material was mixed with DMSO to form a slurry, and a vertical gradient magnetic force was applied in a magnetic field to cause the magnetic Co3O4 nanoparticles to migrate to the membrane surface, then directional freeze casting and solidification of the membrane structure were carried out. The surface and cross-section structure of the membrane were analyzed using a scanning electron microscope (SEM), and the results showed that the photocatalytic membrane had a uniform porous network, the average pore size was about 120 nm, and the porosity was close to 78.5%, which was significantly better than that of the membrane without magnetic induction construction (pore size about 65 nm, porosity 52.1%). At the same time, the specific surface area of the membrane was measured by nitrogen adsorption-desorption BET method, which was 38.2 m 2 / g, which was significantly higher than that of the control group membrane material (24.7 m 2 / g), indicating that it had a larger active interface and mass transfer space.

[0059] As shown in the film flux performance, the composite film of the application reaches 1350 L·m Figure 3 ·h -2 under constant pressure (0.1 MPa) conditions for the filtration flux of simulated antibiotic wastewater (containing 20 mg / L tetracycline), which is 1.5-2 times of ordinary Bi5O7I / Bi film (880 L·m -1 ·h -2 ) and non-magnetic induction film (690 L·m -1 ·h -2 ·h -1 ), fully proving that the structure optimization effectively reduces the water flow resistance of the film and enhances the transmission efficiency, which is extremely suitable for treating large volume of water.

[0060] For catalytic performance, typical antibiotic pollutants such as tetracycline (TC) and sulfamethoxazole (SMX) are selected as target degradable substances, and degradation experiments are carried out under the conditions of light intensity of 100 mW / cm 2 , reaction time of 2 h. As shown in Figure 4 , the removal rates of the Co3O4 / Bi5O7I / Bi film prepared by the application for TC and SMX are 99.1% and 98.7% respectively, and the COD (chemical oxygen demand) removal rates are 96.4% and 95.6% respectively, which are much higher than those of the film material without composite Co3O4 component or without directional structure regulation (degradation rate is about 74%, and COD removal rate is less than 76%). This fully shows that the magnetic component and the structure synergistic effect play an important role in enhancing the visible light response ability and improving the electron-hole separation efficiency.

[0061] In terms of pollution resistance and reuse performance, the photocatalytic film of the application is continuously used for five times of antibiotic wastewater treatment, each time for 2 hours, and is reused after simple physical flushing. As shown in Figure 5 , after five times of continuous use, the degradation rate of the film only decreases by about 2%, the COD removal rate is stably maintained at more than 94%, and the water flux slightly decreases but is still higher than 1300 L·m -2 ·h -1 (see Figure 6 ), showing its excellent structural stability and regeneration ability. In addition, bovine serum albumin (BSA) is further used as an organic pollution model to test the pollution resistance of the film, and the results show that the flux attenuation rate is controlled within 6% after 12 hours of continuous operation, which is better than the conventional non-directional film (flux attenuation is more than 15%), further proving that the large pore structure and hydrophilic surface of the film effectively delay the adsorption and blockage of pollutants on the membrane surface.

[0062] In terms of membrane recovery, due to the introduction of the magnetic Co3O4 component, the prepared membrane can be quickly separated by a magnetic field of 0.3T in 30 seconds, facilitating the rapid removal, recovery and reuse of the membrane in practical applications, and having extremely high engineering potential and environmental friendliness.

[0063] The application utilizes the magnetic induction directional migration and the frozen template cooperative strategy to realize the precise regulation and function integration of the photocatalytic membrane structure.

[0064] Material characterization: SEM, XRD, VSM, BET, UV-Vis-NIR and other technologies are used to evaluate the membrane structure, component distribution, magnetism and photocatalytic performance; water flux and anti-pollution performance tests are used to evaluate the separation performance of the membrane body; simulated wastewater photocatalytic degradation experiments are used to verify the treatment efficiency.

[0065] Application prospect: The photocatalytic membrane of the application is suitable for high-concentration organic wastewater treatment in pharmaceutical, printing and dyeing, pesticide and other industries; upgrading and reconstruction of municipal sewage plants; integrated development of integrated water treatment membrane photocatalytic equipment.

[0066] The implementation principle of the application is: a preparation method and application of a Co3O4 / Bi5O7I / Bi photocatalytic membrane constructed by magnetic induction and direction are disclosed. -2 ·h -1 The flux of the prepared membrane reaches 1350L·m-1·h-1 under 0.1MPa, the degradation rate of tetracycline is more than 99% under visible light / near-infrared irradiation for 2h, the performance attenuation is less than 2% in 5 cycles, and the membrane can be magnetically separated and recovered.

[0067] The embodiments of the specific embodiment are preferred embodiments of the application, but do not limit the protection scope of the application, so that: any equivalent changes made according to the structure, shape, principle of the application should be covered within the protection scope of the application.

Claims

1. A method for preparing a high-flux photocatalytic film with magnetically induced directional construction, characterized in that: The following steps are involved: Step 1: Preparation of photocatalytic functional materials, namely, preparing Bi5O7I powder, Bi nanopowder and Co3O4 nanopowder; Step 2: Preparation of composite photocatalytic slurry: Bi5O7I powder, Bi nanopowder and Co3O4 nanopowder were mixed in a mass ratio of 5:1:2, ethanol and DMSO were added in a volume ratio of 4:1, and a film-forming carrier was added to form a catalytic slurry; Step 3: Magnetic induced migration and membrane construction: placing the above-mentioned catalytic slurry in a vertical gradient magnetic field with a magnetic induction intensity gradient of 0.2 T / cm, so that the magnetic Co3O4 particles and composite clusters migrate and gather on the membrane surface; Step 4: Directional freeze casting and film solidification: Directional freeze casting at -80°C for 12 hours to form longitudinal through-channels; Step 5: vacuum drying and film forming: drying at -60°C and vacuum pressure ≤10Pa to obtain a complete flexible self-supporting film.

2. The method for preparing a high-flux photocatalytic film with magnetically induced directional construction according to claim 1, characterized in that: In step 1, the preparation method of the Bi5O7I powder includes the following steps: weighing 10 mmol Bi(NO3)3·5H2O and dissolving it in 40 mL 0.5 M dilute nitric acid, stirring thoroughly, adding 5 mmol KI, and continuing stirring for 30 minutes; The mixture was transferred to a 100 mL polytetrafluoroethylene-lined autoclave, subjected to hydrothermal reaction at 180°C for 24 h, cooled, centrifuged, washed alternately with ethanol and water, and vacuum dried (60°C, 12 h) to obtain yellow crystalline Bi5O7I powder.

3. The method for preparing a high-flux photocatalytic film with magnetically induced directional construction according to claim 1, characterized in that: In step 1, the preparation method of the Bi nanopowder includes the following steps: weighing 1 mmol of Bi(NO3)3·5H2O, dissolving it in 30 mL of ethylene glycol, adding 0.5 g of PVP, and stirring to form a transparent solution; 0.1M NaBH4 solution (15 mL) was added dropwise to the above solution and reacted at 80°C for 4 h to reduce the metal Bi. 0 The nanoparticles were centrifuged, washed, and dried in vacuum at room temperature for 12 h to obtain black Bi nanopowder.

4. The method for preparing a high-flux photocatalytic film with magnetically induced directional construction according to claim 1, characterized in that: In step 1, the preparation method of the Co3O4 nanopowder The method comprises the following steps: weighing 2 mmol of Co(NO3)2·6H2O and dissolving it in 100 mL of water, adding a 1 M NaOH solution dropwise to adjust the pH to 10, stirring at a constant temperature for 2 hours, and allowing to stand and mature to form cobalt hydroxide; After centrifugal washing, the precipitate was dried and calcined at 500°C in air for 3 h to obtain Co3O4 nanopowder with excellent magnetic responsiveness.

5. The method for preparing a high-flux photocatalytic film with magnetically induced directional construction according to claim 1, characterized in that: In the step 2, the film-forming carrier is polyvinyl alcohol or polyvinylidene fluoride, with a concentration of 6 to 8 wt%.

6. The method for preparing a high-flux photocatalytic film with magnetically induced directional construction according to claim 1, characterized in that: In step 3, the magnetic induction treatment time is 30 minutes.

7. The method for preparing a high-flux photocatalytic film with magnetically induced directional construction according to claim 1, characterized in that: The prepared photocatalytic film has a porosity of ≥75%, an average pore diameter of 120 nm, and is surface-enriched with Co3O4 / Bi5O7I / Bi catalyst.

8. The method for preparing a high-flux photocatalytic film with magnetically induced directional construction according to claim 1, characterized in that: The prepared photocatalytic film has a filtration flux of ≥1300 L·m2 for wastewater containing 20 mg / L tetracycline at 0.1 MPa. -2 ·h -1 .

9. Use of the Co3O4 / Bi5O7I / Bi photocatalytic membrane prepared by the method for preparing a high-flux photocatalytic membrane with magnetically induced orientation as claimed in any one of claims 1 to 8 in wastewater treatment.

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