Catalytic self-cleaning inner pressure type composite nanofiltration membrane, preparation method and application thereof

Abstract

The application discloses a catalytic self-cleaning inner pressure type composite nanofiltration membrane and a preparation method and application thereof. The composite nanofiltration membrane comprises a hollow fiber ultrafiltration base film, the outer surface of the hollow fiber ultrafiltration base film is compounded with a CuCo-MOFs / MXene composite material layer, and the outer surface of the CuCo-MOFs / MXene composite material layer is polymerized with a polyamide separation layer. Through the compounding of CuCo-MOFs / MXene and the polyamide membrane, the large pore structure of the bimetallic MOFs increases the permeability of the membrane, regulates the performance of the nanofiltration separation layer, improves the compactness and thickness, and realizes the improvement of the nanofiltration membrane flux. The CuCo-MOFs / MXene intermediate layer improves the antifouling property of the nanofiltration membrane, and in addition, can intercept the sulfate byproducts generated by the oxidation of persulfate. The flux recovery capacity is improved, and the self-cleaning effect of the membrane is realized. The composite nanofiltration membrane is suitable for the removal of various organic pollutants and the control of pollutants.

Description

Technical Field

[0001] This invention belongs to the field of catalytic membrane separation and wastewater treatment technology, specifically relating to a catalytic self-cleaning internal pressure composite nanofiltration membrane, its preparation method, and its application. Background Technology

[0002] Nanofiltration membrane technology plays a vital role in modern membrane separation technology and is widely used in industrial wastewater treatment, seawater desalination, and material separation. However, nanofiltration membrane technology currently faces two major technical challenges: first, the asymmetric membrane desalination layer is dense and its thickness is difficult to control, resulting in significant flux variations and a marked decrease in desalination efficiency after long-term operation; second, the functional layer structure formed through surface coating, interfacial polymerization, or self-assembly is unstable, making it difficult to precisely control the molecular weight cutoff.

[0003] Hollow fiber nanofiltration membranes possess a more stable component structure, better resistance to hydraulic shock, higher packing density, and higher water production efficiency, offering a wider range of applications compared to spiral wound nanofiltration membranes. For example, patent CN110152499A discloses a nanofiltration membrane and its preparation method, which solves the stability problem of the functional layer of the nanofiltration membrane through the assembly of a tannic acid layer and a polyetheramine layer. Patent CN111054219A proposes a method for preparing a hollow fiber nanofiltration membrane, which effectively suppresses defects during the growth process of the interfacial polymerization separation layer. Patent CN113578066A proposes a method for preparing a modified nanofiltration membrane based on MXene, which controls the thickness and density of the polyamide separation layer through an MXene intermediate layer to optimize the balance and selectivity of the membrane separation layer. However, in the above methods, the hydrophilic groups on the nanofiltration membrane surface are covered due to the cross-linking reaction, reducing its antifouling and hydrophilicity properties, and flux recovery can only be achieved through external chemical cleaning. Therefore, it is necessary to develop a novel nanofiltration composite membrane with high antifouling properties.

[0004] MXene, as a novel two-dimensional material, possesses excellent chemical properties and abundant functional groups, allowing for the modulation of polymer surface properties. Furthermore, the surface of MXene contains active functional groups and coordination unsaturation sites, resulting in superior catalytic performance. MXene composite bimetallic MOF nanomaterials can be used as a transition layer in nanofiltration composite membranes to adjust the hydrophilicity of the nanofiltration membrane, enhance catalytic performance, and improve the separation functional layer and the membrane's self-cleaning ability. Summary of the Invention

[0005] To achieve the above objectives, the present invention provides a method for preparing a catalytic self-cleaning internal pressure composite nanofiltration membrane and its application, so as to achieve the antifouling and self-cleaning properties of the nanofiltration membrane.

[0006] The technical solution of the present invention is as follows:

[0007] The first objective of this invention is to provide a catalytic self-cleaning internal pressure composite nanofiltration membrane, comprising a hollow fiber ultrafiltration base membrane, wherein the outer surface of the hollow fiber ultrafiltration base membrane is composited with a CuCo-MOFs / MXene composite material layer, and the outer surface of the CuCo-MOFs / MXene composite material layer is polymerized with a polyamide separation layer.

[0008] In a further embodiment, the CuCo-MOFs / MXene composite material layer is formed by growing CuCo-MOFs nanoparticles on the surface of MXene material.

[0009] Preferably, the thickness of the MXene material is 20-100 μm; and the thickness of the polyamide separation layer is 40-80 nm.

[0010] The second objective of this invention is to provide a method for preparing a catalytically self-cleaning internal pressure composite nanofiltration membrane, comprising the following steps:

[0011] S1. First, the hollow fiber ultrafiltration membrane is placed in a catalyst solution and ultrasonically treated to obtain a composite ultrafiltration membrane; the catalyst is CuCo-MOFs / MXene.

[0012] S2. The composite ultrafiltration membrane is subjected to interfacial polymerization reaction with a polyamide solution to generate a polyamide separation layer on the outer surface of the composite ultrafiltration membrane, thus obtaining a catalytic self-cleaning internal pressure hollow fiber nanofiltration membrane.

[0013] A further method for preparing the CuCo-MOFs / MXene is as follows:

[0014] S11. Disperse the multilayer MXene material in a solution, and then add a copper source and a cobalt source to mix it into a mixture A;

[0015] S12. Prepare organic ligands into a mixture B;

[0016] S13. Mix mixture A and mixture B and then stir to react, to obtain CuCo-MOFs / MXene.

[0017] The preferred embodiment is that the thickness of the multilayer MXene material in step S11 is 20–100 μm;

[0018] The multilayer MXene material is made by etching the MAX phase, with an etching time of 24–48 h and a temperature of 60–80 °C.

[0019] Specifically, the MAX phase is Ti3AlC2;

[0020] The etching is achieved using an etching solvent, which is a mixture of hydrofluoric acid, hydrochloric acid and sodium fluoride, hydrochloric acid and lithium fluoride, or hydrochloric acid and ammonium fluoride.

[0021] In a further embodiment, the molar ratio of the copper source and the cobalt source in step S11 is 0.5 to 1.0; the copper source is at least one of copper acetylacetonate, copper chloride, and copper sulfate, and the cobalt source is cobalt nitrate hexahydrate.

[0022] The copper source in mixture A has a mass concentration of 1.2–1.8 g / L, the MXene mass concentration is 100 mg / L, and the solvent is a mixture of DMF and isopropanol in a mass ratio of 1:1.

[0023] In a further embodiment, the organic ligand in step S12 is 2,3,6,7,10,11-hexahydroxytriphenyl, dimethylimidazolium, or terephthalic acid; the mass concentration of the mixture B is 1–1.5 g / L; and the solvent is a mixture of DMF and isopropanol in a mass ratio of 1:1.

[0024] In step S13, the stirring reaction is carried out at 150°C under aqueous conditions for 6–8 hours.

[0025] In a further embodiment, the mass concentration of the catalyst solution in step S1 is 0.5-5%, and the ultrasonic treatment temperature is 60-90℃ for 2-4 hours. The hollow fiber ultrafiltration membrane needs to be treated with an alkaline solution, that is, it is immersed in an alkaline solution.

[0026] In a further embodiment, the interfacial polymerization reaction in step S2 refers to immersing the composite ultrafiltration membrane in an aqueous polyamine solution, and then immersing it in an oil-phase polyacrylamide chloride solution, thereby generating a polyamide separation layer through interfacial polymerization. The thickness of the polyamide separation layer is 40-80 nm.

[0027] The preferred embodiment is that the solvent in the aqueous polyamine solution is anhydrous piperazine, the mass fraction of the aqueous polyamine solution is 0.5-0.8 wt%, and the composite ultrafiltration membrane is immersed in the aqueous polyamine solution for 2-10 min.

[0028] The oil-phase polyacrylamide chloride solution is formed by dissolving trimesoyl chloride in n-hexane solution, with a concentration of 0.2-0.5 wt%. The composite ultrafiltration membrane is immersed in the oil-phase polyacrylamide chloride solution for 1-3 minutes.

[0029] The third objective of this invention is to provide an application of the above-mentioned catalytic self-cleaning internal pressure composite nanofiltration membrane, which is used as an internal pressure membrane for salt separation or contaminant removal in an oxidation system.

[0030] Oxidation systems include persulfate oxidation systems, heterogeneous Fenton systems, or photoelectrocatalytic oxidation systems.

[0031] In a further embodiment, the pollutants include novel pollutants such as antibiotics and tetrabromobisphenol A flame retardants, or mixtures of conventional pollutants such as rhodamine B and bisphenol A with sulfates.

[0032] The pure water flux of the internal pressure membrane reaches 40-60 LMH bar. ～1 The operating cycle flux recovery rate is greater than 95%, the sulfate rejection rate reaches 95% to 99.2%, and the pollutant removal rate reaches 92% to 95%.

[0033] This application proposes a novel method for preparing an organic-inorganic catalytic self-cleaning internal pressure composite nanofiltration membrane. First, a hollow fiber ultrafiltration membrane base is prepared using a phase inversion method. Then, copper-cobalt MOF nanoparticles are grown on the surface of MXene material and immersed in the base membrane surface, forming the composite nanofiltration membrane through interfacial polymerization. Because a CuCo-MOF / MXene composite material layer exists between the base membrane and the separation layer, it can regulate the permeation and retention capacity of the selective separation layer, thus stabilizing its structure. Under internal pressure operation, in persulfate oxidation, heterogeneous Fenton, or photoelectrocatalytic oxidation systems, the membrane first passes through the inner base membrane, then the intermediate composite material layer, and finally reaches the selective separation layer. The copper-cobalt bimetallic MOFs (CuCo-MOFs) activate persulfate or hydrogen peroxide, generating reactive oxygen species such as sulfate radicals and hydroxyl radicals, which degrade organic pollutants on the membrane surface and within the pores, alleviating membrane fouling and improving membrane hydrophilicity, thereby achieving the self-cleaning property of the composite nanofiltration membrane. In addition, the sulfate ions generated by the persulfate oxidation system can be retained by the selective separation layer, reducing the back-end treatment of sulfate and lowering the load on the selective separation layer.

[0034] The present invention has the following beneficial effects:

[0035] (1) The present invention proposes a method for preparing a catalytic self-cleaning internal pressure composite nanofiltration membrane. By introducing a bimetallic CuCo-MOFs intermediate layer, the MXene material's sheet structure is utilized to enhance the dual electron transport capability and improve catalytic efficiency.

[0036] (2) Through the organic-inorganic hybridization of CuCo-MOFs / MXene, the macroporous structure of bimetallic MOFs increases the permeability of the membrane, which can regulate the performance of the separation layer, improve its compactness, and achieve the increase of flux and the ability to permeate monovalent salts.

[0037] (3) In the persulfate oxidation system, the CuCo-MOFs / MXene composite material layer in the middle position improves the antifouling properties of the nanofiltration membrane and can also retain the sulfate byproducts generated by persulfate oxidation.

[0038] (4) The composite nanofiltration membrane of the present invention is suitable for the removal of various organic pollutants and the control of pollutants. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the internal pressure composite nanofiltration membrane in this invention. Detailed Implementation

[0040] The present invention will be further described below with reference to specific embodiments, but the essence of the present invention is not limited to the embodiments described below. Unless otherwise specified, the methods described are conventional methods, and the materials described are available from publicly available commercial sources unless otherwise specified. Those skilled in the art should know that any simple modifications or substitutions based on the essence of the present invention fall within the scope of protection claimed by the present invention.

[0041] Example 1:

[0042] A schematic diagram of the structure of a catalytic self-cleaning internal pressure composite nanofiltration membrane in this invention is shown below. Figure 1 As shown, it includes a hollow fiber ultrafiltration base membrane 1, the outer surface of which is coated with a CuCo-MOFs / MXene composite material layer 2, and the outer surface of which is polymerized with a polyamide separation layer 3, the thickness of which is 40-80 nm.

[0043] The CuCo-MOFs / MXene composite layer 2 is formed by growing CuCo-MOFs nanoparticles on the surface of MXene material. In this embodiment, the thickness of the MXene material is 20–100 μm.

[0044] The hollow fiber ultrafiltration membrane used in this application is existing and can be prepared by the following methods:

[0045] Cellulose acetate, polymer C (polyethersulfone, polyvinylidene fluoride, or polytetrafluoroethylene), and polyvinylpyrrolidone are mixed in a mass ratio of 1:3-5:0.5-1, and then the surfactant Tween 80 is added. The mixture is then dissolved in DMAC (dimethylacetamide) or NMP (N-methylpyrrolidone), and the polymer is stirred to degas the spinning solution. After phase inversion, an asymmetric hollow fiber ultrafiltration membrane with a pore size of 0.05-0.1 μm is prepared.

[0046] Example 2:

[0047] 1. Mix 15g of cellulose acetate, 63g of polyvinylidene fluoride, 15g of polyvinylpyrrolidone, and 7g of Tween 80. Dissolve in 100ml of LDMAC. After stirring and degassing the polymer, use the resulting spinning solution for phase inversion to prepare a hollow fiber ultrafiltration membrane with a pore size of 0.05μm. Immerse the membrane in a 50% pure water-glycerol mixture for later use.

[0048] 2. Weigh out 1 g of Ti3AlC2 and place it in 50 mL of a 9 M mixed solution (HCl and LiF). Disperse the mixture ultrasonically for 30 min and react at 70 °C for 24 h at a rate of 500 rpm. Wash the precipitate with anhydrous ethanol until impurities are removed. The prepared multilayer MXene has a thickness of approximately 80 μm.

[0049] 3. Disperse 0.01g of the multilayer MXene prepared above in 100mL of a mixture of DMF and isopropanol (mass ratio 1:1), then weigh 0.15g of copper acetylacetonate and 0.2g of cobalt nitrate hexahydrate and dissolve them in the above dispersion to form mixture A.

[0050] Mixture B (0.15g) was prepared by adding 2,3,6,7,10,11-hexahydroxytriphenyl to a mixture of DMF and isopropanol at a mass ratio of 1:1.

[0051] Mixture A and mixture B were thoroughly mixed and transferred to a reaction vessel, where they were stirred and reacted in a water bath at 150°C for 6 hours. After washing and drying, the CuCo-MOFs / MXene catalyst was obtained.

[0052] 4. Before use, dry the hollow fiber ultrafiltration membrane and soak it in a 1M sodium hydroxide solution for 7 hours under heating conditions to obtain alkali treatment.

[0053] 5. Weigh 0.5g of the CuCo-MOFs / MXene catalyst prepared above and dissolve it in 100mL of deionized water. Place the hollow fiber ultrafiltration membrane after alkaline treatment in the solution and sonicate for 1 hour. An intermediate transition layer (CuCo-MOFs / MXene composite material layer) with a thickness of 0.5-1mm is formed on the outer surface of the hollow fiber ultrafiltration membrane to obtain the CuCo-MOFs / MXene composite ultrafiltration membrane.

[0054] The composite ultrafiltration membrane obtained above was first soaked in a 0.5 wt% anhydrous piperazine aqueous solution for 2 minutes to wash off surface impurities, and then immersed in a 0.3 wt% trimesoyl chloride solution for 2 minutes. A polyamide separation layer with a thickness of 50 nm was generated through interfacial polymerization. This yielded a catalytically self-cleaning internal pressure composite nanofiltration membrane with a three-layer structure from the inside out: an inner base membrane, a middle composite material layer, and an outer polyamide separation layer.

[0055] The catalytic self-cleaning internal pressure composite nanofiltration membrane prepared in this embodiment is an internal pressure membrane. It treats organic pollutants in a persulfate oxidation system with a persulfate concentration of 20 mg / L. The composite nanofiltration membrane achieves a pure water flux of 50 LMH bar. 1 The initial concentration of tetracycline in the organic pollutants was 20 mg / L. After filtration, the concentration of tetracycline in the effluent was 1.2 mg / L, and the tetracycline removal rate was 94%.

[0056] Comparative example:

[0057] Using an existing hollow fiber composite nanofiltration membrane as a comparative example, which consists of a base membrane and a polyamide separation layer, it does not have the intermediate CuCo-MOFs / MXene composite material layer compared to Example 1.

[0058] Under the same conditions as in Example 1, the initial concentration of tetracycline was 20 mg / L, and the concentration of tetracycline in the effluent after filtration was 13.5 mg / L. The flux recovery rate of the hollow fiber composite nanofiltration membrane was only about 75%.

[0059] Therefore, the catalytic self-cleaning internal pressure hollow fiber nanofiltration membrane prepared in Example 1 of this application has a CuCo-MOFs / MXene composite material layer, so the membrane's operating cycle flux recovery rate is rapidly increased to 95%, and the sulfate rejection rate after catalytic oxidation reaches 98%.

[0060] The method for determining the pure water flux is as follows:

[0061] The pure water flux of the membrane was measured using a cross-flow filtration device. The membrane was cast into a columnar module with an internal surface area of ​​0.15 m². 2 The pure water flux was measured at an inlet pressure of 2 bar. Jw1=V / (A*t), where V: liquid volume passing through, A: membrane area, and t: filtration time.

[0062] Flux recovery rate determination: The influent concentration and humic acid concentration were both 20 mg / L. After one cycle of operation, the membrane was removed, immersed in ultrapure water and rinsed for 60 min, then irradiated under a 300W UV lamp for 30 min. The pure water flux Jw2 and flux recovery rate were then measured.

[0063] The pollutant rejection rate was determined by setting the influent pollutant concentration and persulfate concentration to 20 mg / L at an influent membrane pressure of 2 bar. The concentrations and rejection rates after rejection were then measured. Cf: Influent pollutant concentration, Cp: Effluent pollutant concentration.

[0064] Example 3:

[0065] Mix 18g of cellulose acetate, 60g of polyethersulfone, 12g of polyvinylpyrrolidone, and 5g of Tween 80. Dissolve in 100mL of NMP (N-methylpyrrolidone). After heating and stirring to degas the polymer, the spinning solution is used to prepare a hollow fiber microfiltration membrane with a pore size of 0.1μm through phase inversion. The membrane is then immersed in a mixture of pure water and glycerol for later use. Before use, the membrane is dried and then immersed in a 1M sodium hydroxide solution under heating conditions for 6 hours.

[0066] Weigh out 1 g of Ti3AlC2 and place it in 50 mL of 50% ammonium fluoride solution. Disperse the mixture ultrasonically for 30 min and react at 500 rpm at 70 °C for 36 h. Wash the precipitate with anhydrous ethanol until surface impurities are completely removed. The precipitate yields a multilayer MXene with a thickness of approximately 60 μm.

[0067] The 0.01 g multilayer MXene prepared above was thoroughly dispersed in a 100 mL mixture of DMF and isopropanol (mass ratio 1:1). Then, 0.18 g of copper acetylacetonate and 0.24 g of cobalt nitrate hexahydrate were weighed and dissolved in the above dispersion to form mixture A. Next, 0.12 g of 2,3,6,7,10,11-hexahydroxytribenzene was added to a 1:1 mixture of DMF and isopropanol to prepare mixture B. Finally, mixture A and mixture B were thoroughly mixed and transferred to a reactor, where they were stirred and reacted in a 150 °C water bath for 8 h. After washing and drying, the CuCo-MOFs / MXene catalyst was obtained.

[0068] Weigh 0.2 g of the CuCo-MOFs / MXene catalyst prepared above and dissolve it in 100 mL of deionized water. Place the hollow fiber ultrafiltration membrane treated with alkali solution into the solution and sonicate for 1 h. An intermediate transition layer (CuCo-MOFs / MXene composite material layer) with a thickness of 0.2-0.5 mm is formed on the outer surface of the hollow fiber ultrafiltration membrane to obtain the CuCo-MOFs / MXene composite microfiltration membrane.

[0069] The composite ultrafiltration membrane obtained above was then immersed in a 0.5 wt% anhydrous piperazine aqueous solution for 2 min, and after washing away surface impurities, it was immersed in a 0.3 wt% trimesoyl chloride solution for 2 min. A polyamide separation layer with a thickness of 50 nm was generated through interfacial polymerization. This yielded a catalytically self-cleaning internal pressure composite nanofiltration membrane with a three-layer structure from the inside out: an inner base membrane, a middle composite material layer, and an outer polyamide separation layer.

[0070] The composite nanofiltration membrane prepared in this embodiment is an internal pressure membrane. It treats organic pollutants in an oxidation system (persulfate oxidation system, persulfate concentration of 20 mg / L) and is detected using the same method as in Example 1. The pure water flux of the composite nanofiltration membrane reaches 40 LMH bar. -1 The initial concentration of Rhodamine B in the organic pollutant was 20 mg / L. After filtration, the concentration of Rhodamine B in the effluent was 1.5 mg / L, and the removal rate of Rhodamine B reached 92.5%.

[0071] Compared to a simple hollow fiber composite nanofiltration membrane without an intermediate transition layer, the membrane in this embodiment exhibits a 95% flux recovery rate over its operating cycle, a sulfate concentration of 15 mg / L after catalytic oxidation, a sulfate concentration of 0.12 mg / L after filtration, and a rejection rate of 99.2%. Simultaneously, it enhances the membrane's antifouling performance and achieves catalytic self-cleaning.

[0072] Example 4:

[0073] Mix 15g cellulose acetate, 70g polyethersulfone, 10g polyvinylpyrrolidone, and 5g Tween 80. Dissolve in 100mL NMP (N-methylpyrrolidone). After heating and stirring to degas the polymer, spin the solution and prepare a hollow fiber microfiltration membrane with a pore size of 0.1μm through phase inversion. Soak the membrane in a pure water-glycerol mixture for later use. Before use, dry the base membrane and soak it in a 1M sodium hydroxide solution under heating conditions for 6 hours.

[0074] Weigh out 1 g of Ti3AlC2 and place it in 40 mL of hydrofluoric acid solution. Disperse the mixture by sonication for 30 min and react at 500 rpm at 60 °C for 24 h. Wash the precipitate with anhydrous ethanol until surface impurities are completely removed. The precipitate yields multilayer MXene with a thickness of approximately 80 μm.

[0075] The 0.01 g multilayer MXene prepared above was thoroughly dispersed in a 100 mL mixture of DMF and isopropanol (mass ratio 1:1). Then, 0.15 g of copper acetylacetonate and 0.2 g of cobalt nitrate hexahydrate were weighed and dissolved in the above dispersion to form mixture A. Next, 0.15 g of 2,3,6,7,10,11-hexahydroxytribenzene was added to a 1:1 mixture of DMF and isopropanol to prepare mixture B. Finally, mixture A and mixture B were thoroughly mixed and transferred to a reactor, where they were stirred and reacted in a 150 °C water bath for 7 h. After washing and drying, the CuCo-MOFs / MXene catalyst was obtained.

[0076] 0.2 g of the prepared CuCo-MOFs / MXene catalyst was dissolved in 100 mL of deionized water. The alkaline-treated base membrane was placed in the solution and sonicated for 1 h. An intermediate transition layer (CuCo-MOFs / MXene composite material layer) with a thickness of 0.2–0.5 mm was formed on the outer surface of the hollow fiber ultrafiltration base membrane, resulting in a CuCo-MOFs / MXene composite microfiltration membrane. The obtained composite ultrafiltration membrane was then immersed in 0.8 wt% anhydrous piperazine aqueous solution for 8 min to remove surface impurities, and then immersed in 0.5 wt% trimesoyl chloride solution for 3 min. A polyamide separation layer with a thickness of 80 nm was generated through interfacial polymerization. This yielded a catalytically self-cleaning internal pressure composite nanofiltration membrane with a three-layer structure from the inside out: an inner base membrane, an intermediate composite material layer, and an outer polyamide separation layer.

[0077] The composite nanofiltration membrane prepared in this embodiment is an internal pressure membrane. When treating organic pollutants in an oxidation system (persulfate oxidation system, where the persulfate concentration is 20 mg / L), the composite nanofiltration membrane achieves a pure water flux of 50 LMH bar. -1 The initial concentration of tetracycline in the organic pollutant was 20 mg / L. After filtration, the concentration of tetracycline in the effluent was 1.0 mg / L, and the tetracycline removal rate was 95%.

[0078] Compared with a simple hollow fiber composite nanofiltration membrane without an intermediate transition layer, the composite nanofiltration membrane prepared in this embodiment has an improved cycle flux recovery rate of 96%. The sulfate concentration after catalytic oxidation in the system is 18 mg / L, and the sulfate concentration after filtration is 0.15 mg / L, with a rejection rate of 99.16%. At the same time, the membrane's antifouling performance is improved, and the membrane's catalytic self-cleaning function is realized.

[0079] The above description of the embodiments is provided to enable those skilled in the art to understand and apply the present invention. It will be apparent to those skilled in the art that various modifications can be made to the embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the embodiments described herein, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A catalytic self-cleaning internally pressurized composite nanofiltration membrane, characterized by: The hollow fiber ultrafiltration base film is compounded with a CuCo-MOFs / MXene composite material layer on the outer surface of the hollow fiber ultrafiltration base film, and a polyamide separation layer is polymerized on the outer surface of the CuCo-MOFs / MXene composite material layer. The CuCo-MOFs / MXene composite material layer is formed by growing CuCo-MOFs nanoparticles on the surface of the MXene material.

2. The catalytic self-cleaning internal pressure composite nanofiltration membrane according to claim 1, characterized in that: The thickness of the MXene material is 20-100 microns, and the thickness of the polyamide separation layer is 40-80 nanometers.

3. The preparation method of the catalytic self-cleaning internal pressure composite nanofiltration membrane according to claim 1 or 2, characterized in that: The method comprises the following steps: S1, first, the hollow fiber ultrafiltration base film is treated with ultrasound in a catalyst solution to obtain a composite ultrafiltration membrane; the catalyst is CuCo-MOFs / MXene; S2, the composite ultrafiltration membrane is subjected to interfacial polymerization with a polyamide solution to form a polyamide separation layer on the outer surface of the composite ultrafiltration membrane, thereby obtaining a catalytic self-cleaning internal pressure type hollow fiber nanofiltration membrane.

4. The method of claim 3, wherein: The preparation method of the CuCo-MOFs / MXene is as follows: S11, the multi-layer MXene material is dispersed in a solution, and then a copper source and a cobalt source are mixed to form a mixed solution A; S12, an organic ligand is mixed to form a mixed solution B; S13, the mixed solution A and the mixed solution B are mixed and subjected to stirring reaction to obtain CuCo-MOFs / MXene.

5. The method of claim 4, wherein: The thickness of the multi-layer MXene material in step S11 is 20-100 microns. The multi-layer MXene material is prepared by etching a MAX phase, and the etching time is 24-48 hours and the temperature is 60-80 degrees Celsius. The MAX phase is Ti3AlC2. The etching is achieved by using an etching solvent, and the etching solvent is a mixed solution of hydrofluoric acid, hydrochloric acid and sodium fluoride, a mixed solution of hydrochloric acid and lithium fluoride, or a mixed solution of hydrochloric acid and ammonium fluoride.

6. The method of claim 4, wherein: The molar ratio of the copper source to the cobalt source in step S11 is 0.5-1.0; the copper source is at least one of copper acetylacetonate, copper chloride and copper sulfate, and the cobalt source is cobalt nitrate hexahydrate; In the mixed solution A, the mass concentration of the copper source is 1.2-1.8 g / L, the mass concentration of MXene is 100 mg / L, and the solvent is a mixed solution of DMF and isopropyl alcohol in a mass ratio of 1:

1.

7. The method of claim 4, wherein: In step S12, the organic ligand is 2,3,6,7,10,11-hexahydroxytriphenyl or dimethyl imidazole or terephthalic acid, the mass concentration of the mixed solution B is 1-1.5 g / L, and the solvent is a mixed solution of DMF and isopropyl alcohol in a mass ratio of 1:

1.

8. The method of claim 4, wherein: In step S13, the stirring reaction is carried out under the condition of 150 degrees Celsius water solution for 6-8 hours.

9. The method of claim 3, wherein: In step S1, the mass concentration of the catalyst solution is 0.5-5%, the temperature of the ultrasonic treatment is 60-90 degrees Celsius, and the time is 2-4 hours; The hollow fiber ultrafiltration base film needs to be treated with lye.

10. The method of claim 3, wherein: In step S2, the interfacial polymerization refers to immersing the composite ultrafiltration membrane in an aqueous polyamine solution, and then immersing it in an oil polyacyl chloride solution to form a polyamide separation layer by interfacial polymerization, and the thickness of the polyamide separation layer is 40-80 nanometers.

11. The method of claim 10, wherein: The solvent in the aqueous polyamine solution is anhydrous piperazine, the mass fraction of the aqueous polyamine solution is 0.5-0.8 wt%, and the time for immersing the composite ultrafiltration membrane in the aqueous polyamine solution is 2-10 min; The oil phase polyacyl chloride solution is formed by dissolving trimesoyl chloride in a n-hexane solution, and the concentration is 0.2-0.5 wt%, and the time for immersing the composite ultrafiltration membrane in the oil phase polyacyl chloride solution is 1-3 min.

12. Use of the catalytic self-cleaning internally pressurized composite nanofiltration membrane according to any one of claims 1-2, characterized in that: An internal pressure membrane used for salt separation or contaminant removal under an oxidation system.

13. Use according to claim 12, characterised in that: The contaminant includes a mixture of an antibiotic, tetrabromobisphenol A flame retardant, rhodamine B and sulfate or a mixture of bisphenol A and sulfate. The pure water flux of the internal pressure membrane reaches 40-60 LMH / bar, the flux recovery rate in a running cycle is greater than 95%, the rejection rate of sulfate reaches 95%-99.2%, and the removal rate of the contaminant reaches 92-95%.

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