Preparation method of metal-doped carbon-nitrogen polymer-based self-cleaning film for in-situ oxidation pollution reduction and application device of metal-doped carbon-nitrogen polymer-based self-cleaning film

Abstract

The invention discloses a preparation method of a metal-doped carbon-nitrogen polymer, a preparation method of a self-cleaning membrane which takes the metal-doped carbon-nitrogen polymer as a substrate and can realize in-situ oxidation pollution reduction and an application device of the self-cleaning membrane, belongs to the technical field of water pollution treatment, and relates to the technical field of membrane materials. According to the preparation method, a hydrothermal calcining technology is adopted, the carbon-nitrogen polymer is subjected to structure substitution through metal element doping, free radicals and non-free radicals of the prepared metal-doped carbon-nitrogen polymer are subjected to synergistic reaction in the catalysis process, and the metal-doped carbon-nitrogen polymer has multifunctional oxidation activity of catalytic ozonation, photocatalysis and catalytic ozonation synergistic photocatalysis. The metal-doped carbon-nitrogen polymer-based self-cleaning membrane capable of realizing in-situ oxidation pollution reduction is prepared by loading a metal-doped polymer material into a pre-spinning solution composed of a high-molecular material, and the self-cleaning membrane can quickly respond to ozone and a lamp tube light source by virtue of the polymer material loaded on the membrane; and hydroxyl radicals, superoxide radicals, singlet oxygen and the like are generated to degrade pollutants attached to the surface of the self-cleaning membrane, so that efficient in-situ self-cleaning of membrane pollution is realized, and the problem of extra cost caused by shutdown due to the membrane pollution problem in the petrochemical wastewater industry can be effectively relieved.

Description

[0001] The present invention belongs to the technical field of water pollution control, mainly relates to the technical field of membrane materials, and specifically relates to a preparation and use device of a metal-doped carbon-nitrogen polymer-based self-cleaning membrane for in-situ oxidation and pollution reduction of biofilm technology used in water pollution control. Background Art

[0002] Membrane separation technology has attracted much attention in the field of water pollution control due to its advantages such as simple operation, environmental protection, and energy saving. However, during the long-term operation of the membrane, membrane pollution will reduce the permeability of the membrane, resulting in reduced flux and increased costs. This not only greatly weakens the separation efficiency of the membrane material for wastewater, but also causes irreversible damage to the membrane material. At present, most of the treatment methods for membrane pollution exist in static treatment of membrane materials, such as adding coatings to the surface of membrane materials. These methods can only alleviate membrane pollution. After long-term operation, there is still the problem of membrane pollution requiring replacement of materials, and it is difficult to fundamentally solve the problem of membrane pollution.

[0003] The prepared metal-doped carbon-nitrogen polymer reacts synergistically with free radicals and non-free radicals during the catalytic process, and has multifunctional oxidation activities of ozone catalytic oxidation, photocatalysis, and ozone catalytic oxidation synergistic photocatalysis. The metal-doped carbon-nitrogen polymer-based self-cleaning membrane continues the excellent performance of the powder polymer, and can quickly respond to ozone and light sources of lamps, produce hydroxyl radicals, superoxide radicals, and singlet oxygen, etc., to degrade pollutants attached to the surface of the self-cleaning membrane, thereby achieving efficient in-situ self-cleaning of membrane pollution. The research and development of in-situ oxidation and pollution reduction self-cleaning membrane materials can greatly reduce the attachment of pollutants to the membrane surface, extend the life of the membrane, reduce water treatment costs, and promote the application and development of membrane separation technology in the field of water pollution control. Summary of the invention

[0004] The purpose of the present invention is to solve the membrane pollution challenge faced by membrane separation technology in the field of water pollution control, and to provide a preparation method and application device of a self-cleaning membrane for in-situ oxidation and pollution reduction applied to membrane technology. The prepared metal-modified carbon-nitrogen polymer-based self-cleaning membrane has excellent hydrophobic properties, ozone catalytic oxidation ability, photocatalytic ability and ozone catalytic oxidation synergistic photocatalytic multifunctional oxidation ability. During the oxidation process, hydroxyl radicals, superoxide radicals and singlet oxygen can be generated, and pollutants attached to the surface of the self-cleaning membrane can be mineralized in situ.

[0005] To achieve the above object, the present invention first provides a metal-doped carbon-nitrogen polymer applied to water treatment technology and a method for preparing a metal-doped carbon-nitrogen polymer-based self-cleaning membrane for in-situ pollution reduction and oxidation, and the specific steps are as follows:

[0006] S1. Dissolve an appropriate amount of melamine and cyanuric acid in hot water quickly, and then slowly drip the cyanuric acid solution into the melamine solution, and stir for a period of time to obtain a white suspension;

[0007] S2, adding an appropriate amount of metal salt to the white suspension in step S1, stirring for a period of time under a certain temperature condition until the mixture is uniform, to obtain a mixed solution;

[0008] S3, centrifuging the mixed solution of step S2, washing with deionized water, transferring the white precipitate to the inner lining of a reactor, adding an appropriate amount of N,N-dimethylacetamide, stirring at room temperature until the mixture is uniformly mixed, and then transferring the mixture to a reactor to obtain a metal-doped carbon-nitrogen polymer precursor through a hydrothermal reaction;

[0009] S4, freeze-drying the polymer precursor in step S3 and transferring it to a tube furnace for calcination under a nitrogen atmosphere to obtain a metal-doped carbon-nitrogen polymer powder after calcination;

[0010] S5. Evenly mix the polymer materials polyacrylonitrile (PAN)\polyvinylpyrrole (PVP) and N,N-dimethylformamide (DMF), add a proper amount of the metal-doped carbon-nitrogen polymer powder described in step S4, stir at a certain temperature until there is no particle, and then pressurize and defoam to obtain a pre-spinning solution.

[0011] The pressure defoaming is characterized in that the non-granular mixed liquid is poured into a round-bottom flask, which is connected to a vacuum filter, and the purpose of defoaming is achieved by increasing the pressure in the flask to cause bubbles to float and burst.

[0012] S6. Add the pre-spinning solution of step S5 into a needle tube container, fix it in an electrospinning device, and prepare a nanofiber composite membrane.

[0013] S7. After hot pressing the metal-doped carbon-nitrogen polymer-based self-cleaning membrane for in-situ oxidation and fouling reduction, soak it in hot water for a period of time to remove PVP, and then naturally dry it to obtain an in-situ oxidation and fouling reduction self-cleaning membrane with excellent self-cleaning ability.

[0014] S8. placing the prepared metal-doped carbon-nitrogen polymer-based self-cleaning film in a transparent photocatalytic synergistic ozone catalytic device to test its pollutant degradation performance under the synergistic effect of ozone and light;

[0015] The photocatalytic synergistic ozone catalytic device is a transparent cup-shaped container, with a cooling circulating water system at the lower end to ensure constant temperature during the experiment, an air inlet and an air outlet at the upper end, connected to an ozone generator, and the top is sealed with a transparent quartz glass sheet, and a xenon lamp is located above the device.

[0016] Preferably, the mass ratio of melamine to cyanuric acid is 0.5 to 1:1 (mol:mol), the temperature of high-temperature water is 80 to 90° C., the stirring temperature of melamine and cyanuric acid is 60 to 80° C., and the stirring time is 1 to 3 hours;

[0017] Preferably, the metal salt (the required metal ions are provided by the following substances: manganese chloride, iron chloride, chromium chloride, nickel chloride) is added in an amount of 10 mg to 40 mg, the stirring temperature after adding the metal salt is 65 to 85° C., and the stirring time is 1 to 2 h;

[0018] Preferably, the deionized water washing times are 2 to 4 times, the reaction temperature of the hydrothermal reaction conditions is 160 to 200° C., and the reaction time is 7 to 9 hours;

[0019] Preferably, the tubular furnace calcination conditions are calcination at 520°C for 4 to 6 hours, and a heating rate of 2 to 2.5°C / min;

[0020] Preferably, the amount of the metal-doped carbon nitride nanotubes added is 0.8 to 1.5 g, the stirring temperature is 60 to 80° C., and the stirring time is 16 to 24 h;

[0021] Preferably, the temperature of the high-temperature water for soaking the self-cleaning membrane is 60-80° C., and the soaking time is 8-12 hours.

[0022] Preferably, the pollutant is one of the typical pollutants in petrochemical wastewater. The pollutant used in this experiment is p-nitrophenol, and the pollutant concentration is 10-50 mg / L.

[0023] The invention also provides a device and method for using an in-situ oxidation self-cleaning membrane, the specific contents of which are as follows:

[0024] An in-situ oxidation and pollution reduction self-cleaning membrane device, characterized in that it mainly comprises: (1) a box-type housing (2) a membrane slot (3) an air inlet (4) a sewage inlet (5) five groups of membranes (6) a mixed liquid channel (7) a clean water outlet (8) a ring-shaped light tube (9) and a central transparent pipe

[0025] Preferably, the main membrane material used in the five groups of (5) membrane sheets is the in-situ oxidation and pollution reduction self-cleaning membrane with oil-water separation performance and excellent self-cleaning ability as described in claim 1; (3) the air inlet is ozone; (8) the annular lamp tube can use one or more of ultraviolet lamps, mercury lamps, LED lamps, and xenon lamp tubes.

[0026] An in-situ oxidation pollution reduction self-cleaning membrane device with oil-water separation performance and excellent self-cleaning ability is characterized in that sewage enters (6) a mixed liquid channel through (4) a sewage inlet pipe, and ozone also enters a central pipeline through (3) an air inlet, the sewage and ozone are mixed for the first time, the annular light tube (8) is turned on, and under light conditions, the sewage passes through (5) a membrane to realize the ozone catalysis, photocatalysis and ozone catalytic oxidation synergistic photocatalytic performance of the self-cleaning membrane, the pollutants respond on the membrane surface, and free radicals and non-free radicals are generated to mineralize the pollutants in situ, and the attachment of pollutants to the membrane surface can be reduced; after being filtered by five groups of (5) membranes, the clean water flows out from the outlet.

[0027] Compared with the prior art, the advantages of this invention are:

[0028] 1. The present invention adopts hydrothermal calcination technology, and replaces the structure of carbon-nitrogen polymer by metal element doping and non-metallic amino modification. The prepared metal-doped carbon-nitrogen polymer has a synergistic reaction of free radicals and non-free radicals in the catalytic process, and has multifunctional oxidation activity of ozone catalytic oxidation, photocatalysis and ozone catalytic oxidation synergistic photocatalysis. At the same time, electrostatic spinning technology is used to realize the immobilization of powder materials, avoiding the disadvantage that powder catalytic materials are difficult to recycle in water pollution treatment technology, and enabling the membrane to produce surface stimulation response to ozone and light, promoting the generation of active oxygen on the membrane surface, and accelerating the mineralization rate of pollutants.

[0029] 2. Compared with the existing membrane pollution control process, the nanofiber structure in the in-situ oxidation self-cleaning membrane is compact and has good stability. It has excellent risk resistance in membrane separation technology. At the same time, the self-cleaning membrane can respond to ozone and light at the same time. It can adjust the treatment intensity by adjusting the ozone concentration, light intensity and other conditions during the pollution control process. It can also flexibly adjust the surface stimulus response source according to the influent water quality and the risk of membrane damage, thereby reducing the self-cleaning cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram of an in-situ oxidation and pollution reduction self-cleaning membrane device;

[0031] Figure 2 This is a surface scanning electron microscope image of the in-situ oxidation-reducing and self-cleaning membrane of Example 1;

[0032] Figure 3 This is a physical picture of the in-situ oxidation and pollution reduction self-cleaning membrane prepared in Example 1;

[0033] Figure 4 This is a performance diagram of the in-situ oxidation and fouling reduction self-cleaning membrane prepared in Example 1 for degrading 30 mg / L p-nitrophenol simulated wastewater. DETAILED DESCRIPTION

[0034] The present invention is further described below in conjunction with specific embodiments, which are only some embodiments of the present invention, not all embodiments. The following embodiments are used to illustrate the technical solutions of the present invention rather than to limit the scope of protection of the present invention. It should be understood by those skilled in the art that all other embodiments obtained without creative work are within the scope of protection of the present invention.

[0035] The technical solution of the embodiment of the present invention is to solve the above problems, and the specific ideas proposed are as follows:

[0036] The present invention provides a method for preparing a metal-modified carbon-nitrogen polymer and a metal-modified carbon-nitrogen polymer-based self-cleaning film. The present invention adopts hydrothermal calcination technology, and structurally replaces the carbon-nitrogen polymer through modification of metal elements and non-metallic amino groups. The prepared metal-doped carbon-nitrogen polymer reacts synergistically with free radicals and non-free radicals during the catalytic process, and has multifunctional oxidation activities of ozone catalytic oxidation, photocatalysis, and ozone catalytic oxidation synergistic photocatalysis. At the same time, electrostatic spinning technology is used to realize the immobilization of powder polymer materials, and the prepared self-cleaning film can produce surface stimulation responses to ozone and light, promote the generation of active oxygen on the membrane surface, and accelerate the mineralization rate of pollutants.

[0037] The present invention also provides an application device for an in-situ oxidation pollution reduction self-cleaning membrane. The sewage passing through the device can produce a response on the membrane surface, generating free radicals and non-free radicals to carry out in-situ mineralization of pollutants. At the same time, the treatment intensity can be adjusted by adjusting conditions such as ozone concentration and light intensity during the pollution control process, and the surface stimulus response source can be flexibly adjusted according to the influent water quality and the risk of membrane damage, thereby reducing the self-cleaning cost.

[0038] Example 1

[0039] An embodiment of the present application provides a method for preparing a metal-doped carbon-nitrogen polymer and a metal-doped carbon-nitrogen polymer-based in-situ oxidation self-cleaning film, and the preparation method is as follows:

[0040] An appropriate amount of melamine and cyanuric acid (1:1 moL) were quickly dissolved in hot water at 90°C. After dissolution, the cyanuric acid solution was slowly dripped into the melamine solution at 90°C. After stirring at 80°C for 1 hour, 25 mg of anhydrous manganese chloride was added to the uniformly mixed white suspension. Stirring was continued at 80°C for 1 hour until the mixture was uniform. The obtained suspension was centrifuged, washed with deionized water for the third time, and the white precipitate was transferred to the lining of the reactor. 2 mL of N, N-dimethylacetamide was added, and the mixture was transferred to the reactor after stirring. The metal-doped carbon nitrogen polymer powder precursor was obtained by hydrothermal reaction at 180°C for 8 hours. After freeze drying, it was calcined at 520°C for 4 hours (2°C / min) in a nitrogen atmosphere in a tubular furnace to obtain a modified carbon nitride powder. 1.2 g PAN, 0.8 g PVP, and 1 g of the prepared metal-doped carbon nitrogen polymer powder were uniformly dispersed in 10 g DMF solvent, stirred evenly, and then defoamed to obtain a pre-spinning solution.

[0041] The pre-spinning liquid is added into a needle tube container and fixed in an electrospinning device. The nanofiber membrane is obtained by electrospinning and then hot-pressed using a cold laminator. The membrane is then immersed in 80°C water for 8 hours to remove PVP to construct a porous structure. After natural drying, an in-situ oxidation-based fouling-reduction self-cleaning membrane is obtained.

[0042] Example 2

[0043] An embodiment of the present application provides a method for preparing a metal-doped carbon-nitrogen polymer and a metal-doped carbon-nitrogen polymer-based in-situ oxidation self-cleaning film, and the preparation method is as follows:

[0044] An appropriate amount of melamine and cyanuric acid (1:1 moL) were quickly dissolved in hot water at 90°C. After dissolution, the cyanuric acid solution was slowly dripped into the melamine solution at 90°C. After stirring at 80°C for 1 hour, 25 mg of anhydrous cobalt chloride was added to the uniformly mixed white suspension. The mixture was further stirred at 80°C for 1 hour until it was uniformly mixed. 2 mL of N,N-dimethylacetamide was added, and the mixture was transferred to a reactor after stirring. The metal-doped carbon-nitrogen polymer powder precursor was obtained by hydrothermal reaction at 180°C for 8 hours. After freeze-drying, the precursor was calcined at 520°C for 4 hours (2°C / min) in a nitrogen atmosphere in a tubular furnace to obtain a modified carbon nitride powder. 1.2 g of PAN, 0.8 g of PVP, and 1 g of the prepared metal-doped carbon-nitrogen polymer powder were uniformly dispersed in 10 g of DMF solvent. After stirring, the mixture was defoamed to obtain a pre-spinning solution.

[0045] The pre-spinning liquid is added into a needle tube container and fixed in an electrospinning device. The nanofiber membrane is obtained by electrospinning and then hot-pressed using a cold laminator. The membrane is then immersed in 80°C water for 8 hours to remove PVP to construct a porous structure. After natural drying, an in-situ oxidation-based fouling-reduction self-cleaning membrane is obtained.

[0046] Example 3

[0047] An embodiment of the present application provides a method for preparing a nanofiber membrane, and the preparation method is as follows:

[0048] 1.2g PAN and 0.8g PVP were evenly dispersed in 10g DMF solvent, stirred evenly and defoamed to obtain a pre-spinning solution.

[0049] The pre-spinning solution was added into a needle tube container and fixed in an electrospinning device. The nanofiber membrane was obtained by electrospinning and then hot-pressed using a cold laminator. The nanofiber membrane was then immersed in 80°C water for 8 hours to remove PVP to construct a porous structure. The nanofiber membrane was obtained after natural drying.

[0050] Example 4

[0051] An embodiment of the present application provides a method for preparing a metal-doped carbon-nitrogen polymer-based in-situ oxidation self-cleaning film, the preparation method being as follows:

[0052] 1g of metal-doped carbon-nitrogen polymer powder was ultrasonically dispersed in 10mL DMF, mixed with 0.9g of polyacrylonitrile (PAN), and stirred at 60°C for 12h to obtain a pre-spinning solution. The pre-spinning solution was added to a syringe container and fixed in an electrospinning device. After the nanofiber membrane was obtained by electrospinning, it was hot-pressed with a cold laminator, and then soaked in 80°C water for 8h to remove PVP to construct a porous structure. After natural drying, an in-situ oxidation-reducing self-cleaning membrane was obtained.

[0053] Example 5

[0054] This embodiment provides an application device of an in-situ oxidation and pollution reduction self-cleaning membrane, which specifically includes the following parts:

[0055] (1) Box-type housing (2) Diaphragm slot (3) Air inlet (4) Sewage inlet (5) Five groups of diaphragms (6) Mixed liquid channel (7) Clean water outlet (8) Ring-shaped light tube (9) Central transparent pipe; the five groups of diaphragms (5) use the main membrane material in-situ oxidation and pollution reduction self-cleaning membrane; (3) The air inlet is one or more of ozone, oxygen, and air; (8) The ring-shaped light tube can use one or more of ultraviolet lamps, mercury lamps, LED lamps, and xenon lamps.

[0056] Method of use: Sewage enters the (6) mixing liquid channel through the (4) sewage inlet pipe, and ozone also enters the central pipe through the (3) air inlet. The sewage and ozone are mixed for the first time. Turn on the (8) annular light tube. Under light conditions, the sewage passes through the (5) membrane to realize the ozone catalysis, photocatalysis and ozone catalytic oxidation synergistic photocatalytic performance of the self-cleaning membrane. The pollutants respond on the membrane surface, generating free radicals and non-free radicals to mineralize the pollutants in situ, and can reduce the attachment of pollutants on the membrane surface. After being filtered by five groups of (5) membranes, the clean water flows out from the outlet.

Claims

1. A method for preparing a metal-doped carbon-nitrogen polymer-based self-cleaning membrane for in-situ oxidation and pollution reduction, characterized in that: The following steps are involved: Step S1, quickly dissolving an appropriate amount of melamine and cyanuric acid in high-temperature water, and then slowly dripping the cyanuric acid solution into the melamine solution, and stirring for a period of time to obtain a white suspension; Step S2, adding an appropriate amount of metal salt to the white suspension of step S1, stirring for a period of time under a certain temperature condition until the mixture is uniform, to obtain a mixed solution; Step S3, centrifuging the mixed solution of step S2, washing with deionized water, transferring the white precipitate to the inner lining of a reactor, adding an appropriate amount of N,N-dimethylacetamide, stirring at room temperature until the mixture is uniformly mixed, and then transferring the mixture to a reactor to obtain a metal-doped carbon-nitrogen polymer precursor through a hydrothermal reaction; Step S4, freeze-drying the polymer precursor in step S3 and transferring it to a tube furnace for calcination under a nitrogen atmosphere to obtain a metal-doped carbon-nitrogen polymer powder after calcination; Step S5, mix the polymer materials polyacrylonitrile (PAN)\polyvinyl pyrrole (PVP) and N,N-dimethylformamide (DMF) evenly, add an appropriate amount of the metal-doped carbon nitrogen polymer powder described in step S4 thereto, stir at a certain temperature until there is no particle, and then pressurize and defoam to obtain a pre-spinning solution. The pressure defoaming is characterized in that the non-granular mixed liquid is poured into a round-bottom flask, which is connected to a vacuum filter, and the purpose of defoaming is achieved by increasing the pressure in the flask to cause bubbles to float and burst. Step S6, adding the pre-spinning solution of step S5 into the needle tube container, fixing it in the electrospinning device, and preparing the nanofiber composite membrane. Step S7, hot-pressing the metal-doped carbon-nitrogen polymer-based self-cleaning membrane for in-situ oxidation and fouling reduction, soaking it in hot water for a period of time to remove PVP, and naturally drying it to obtain an in-situ oxidation and fouling reduction self-cleaning membrane with excellent self-cleaning ability. Step S8, placing the prepared metal-doped carbon-nitrogen polymer-based self-cleaning film in a transparent photocatalytic synergistic ozone catalytic device, and testing its pollutant degradation performance under the synergistic effect of ozone and light; The photocatalytic synergistic ozone catalytic device is a transparent cup-shaped container, with a cooling circulating water system at the lower end to ensure constant temperature during the experiment, an air inlet and an air outlet at the upper end, connected to an ozone generator, and the top is sealed with a transparent quartz glass sheet, and a xenon lamp is located above the device.

2. The preparation method according to claim 1, characterized in that: In step S1, the mass ratio of melamine to cyanuric acid is 0.5 to 1:1 (mol:mol), the temperature of high-temperature water is 80 to 90° C., the stirring temperature of melamine and cyanuric acid is 60 to 80° C., and the stirring time is 1 to 3 hours; In step S2, the amount of metal salt (the required metal ions are provided by the following substances: manganese chloride, iron chloride, chromium chloride, nickel chloride) added is 10 mg to 40 mg, the stirring temperature after adding the metal salt is 65 to 85° C., and the stirring time is 1 to 2 hours; In step S3, the number of deionized water washing is 2 to 4 times, the reaction temperature of the hydrothermal reaction conditions is 160 to 200° C., and the reaction time is 7 to 9 hours; The calcination conditions in step S4 are calcination at 520° C. for 4 to 6 hours, and a heating rate of 2 to 2.5° C. / min; The amount of metal-doped carbon nitride nanotubes added in step S5 is 0.8-1.5 g, the stirring temperature is 60-80° C., and the stirring time is 16-24 h; In step S7, the temperature of the high temperature water is 60-80° C., and the soaking time is 8-12 hours. The pollutant in step S8 is one of the typical pollutants in petrochemical wastewater. The pollutant used in this experiment is p-nitrophenol, and the pollutant concentration is 10-50 mg / L.

3. A metal-doped carbon-nitrogen polymer-based self-cleaning membrane device for in-situ oxidation and pollution reduction according to the method of claim 1, characterized in that: Mainly include: (1) Box-type housing (2) Diaphragm slot (3) Air inlet (4) Sewage inlet (5) Five groups of diaphragms (6) Mixed liquid channel (7) Clean water outlet (8) Ring light tube (9) Central transparent pipe The main membrane material of the five groups of (5) membrane sheets is the metal-doped carbon-nitrogen polymer-based self-cleaning membrane capable of in-situ oxidation and pollution reduction as described in Claim 1; (3) the air inlet is ozone; (8) the annular lamp tube can use one or more of an ultraviolet lamp, a mercury lamp, an LED lamp, and a xenon lamp tube.

4. A metal-doped carbon-nitrogen polymer-based self-cleaning membrane device capable of in-situ oxidation and pollution reduction as claimed in claim 3, characterized in that Sewage enters the (6) mixing liquid channel through the (4) sewage inlet pipe, and ozone also enters the central pipe through the (3) air inlet. The sewage and ozone are mixed for the first time. The (8) annular light tube is turned on. Under light conditions, the sewage passes through the (5) membrane to realize the ozone catalysis, photocatalysis and ozone catalytic oxidation synergistic photocatalytic performance of the self-cleaning membrane. The pollutants respond on the membrane surface, generating free radicals and non-free radicals to mineralize the pollutants in situ, and can reduce the attachment of pollutants on the membrane surface. After being filtered by five groups of (5) membranes, the clean water flows out from the outlet.

5. A self-cleaning membrane device for in-situ oxidation and pollution reduction as described in claims 3-4, wherein the (5) membrane has multifunctional catalytic activities such as ozone catalytic oxidation, photocatalysis, and ozone catalytic oxidation synergistic photocatalysis; the (8) annular lamp tube can provide sufficient light source during the membrane action process, so that the photocatalytic activity of the membrane can mineralize pollutants under optimal conditions, thereby promoting the realization of online in-situ self-cleaning.

6. A metal-doped carbon-nitrogen polymer-based self-cleaning membrane for in-situ oxidation and pollution reduction prepared by the preparation method according to any one of claims 1 to 2.

7. Application of the metal-doped carbon-nitrogen polymer-based self-cleaning membrane device for in-situ oxidation and pollution reduction as described in claims 3-4 in the field of membrane technology.

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