Polysulfone composite oil-water separation membrane with surface modified by ZIF-7-OH as well as preparation method and application of polysulfone composite oil-water separation membrane

Abstract

The invention discloses a ZIF-7-OH surface modified polysulfone composite oil-water separation membrane as well as a preparation method and application thereof. Through simple blending and non-solvent induced phase inversion, the method comprises the following specific steps: firstly, synthesizing a hydrophobic polymer through free radical polymerization, and then blending the hydrophobic polymer with a polysulfone matrix to form a membrane casting solution; secondly, hydroxylated ZIF-7 (ZIF-7-OH) particles are fixed to the surface of the membrane through a non-solvent induced phase inversion method; wherein due to the introduction of hydroxyl, particles and hydrophobic polymers with siloxane groups can be coupled and fixed on the membrane, so that the stability of the particles on the surface of the membrane is improved, and finally, the super-hydrophobic polysulfone composite membrane for efficient oil-water emulsion separation is obtained. The ZIF-7 particles are creatively hydroxylated and fixed to the surface of the membrane through a coupling effect, and the micro-nano rough structure and the low-surface-energy substance have a synergistic effect, so that the membrane is endowed with super-hydrophobicity and excellent self-cleaning performance, and the composite membrane has efficient oil-water emulsion separation capacity.

Description

Technical Field

[0001] The invention belongs to the field of polymer materials and functional materials, and specifically relates to a polysulfone composite oil-water separation membrane with surface modified ZIF-7-OH and a preparation method and application thereof. Background Art

[0002] With the rapid development of social industrialization, environmental problems have become increasingly prominent. Frequent marine oil spills and oily waste discharges have not only caused huge waste of resources, but also led to serious ecological, environmental and human health problems. Therefore, it is urgent to develop an efficient oil-water separation technology and material. Traditional methods for separating oil-water mixtures include gravity separation, flotation separation, electropolymerization separation, flocculation, adsorption, etc. However, these methods have the disadvantages of high cost, low separation efficiency, and secondary pollution, which greatly limit their application. Therefore, it is of great significance to develop efficient, economical, and environmentally friendly oil recovery technology and new membrane materials for stable emulsion separation.

[0003] Inspired by the special wettability phenomenon in nature, the preparation of artificial superwetting materials has become increasingly popular. In recent years, the effect of special wettability on oil-water separation has aroused great interest. For example, Wang et al. [Wang Y, Yang S, Zhang J, et al. Nature Communications, 2023, 14 (1): 1108.] developed a new capillary-driven confined assembly membrane strategy inspired by the capillary phenomenon in nature, and constructed a switchable wettability smart membrane with CO2 responsiveness. The membrane can be applied to various oil-water systems, including immiscible oil-water mixtures, surfactant-stabilized emulsions, and multiphase emulsions. The separation efficiency is 99.9%, and it has recyclability and excellent self-cleaning properties. However, the membrane is easily damaged during use, the surface is easily contaminated, and there are some defects in mechanical properties, which in turn affect the performance of the membrane. Gao et al. [Gao S, Chen J, Zheng Y, et al. Advanced Functional Materials, 2022, 32(46): 2205990.] constructed the gradient distribution of protocatechuic acid and hydrated calcium alginate on the membrane from the inside to the outside, and proposed the structure of the hydrogel on the membrane. From the inside to the outside of the entire adhesive hydrogel, the content of protocatechuic acid decreased from 100% to 0%, while the content of hydrated calcium alginate increased from 0% to 100%. The innermost protocatechuic acid and the outermost water and calcium alginate were integrated through strong coordination interactions to form a superhydrophilic membrane. The membrane achieves efficient and ultra-stable separation of surfactant-stabilized emulsions with an efficiency of up to 99.9%. However, in the process of synthesizing the membrane, the production process is relatively complicated, and the durability of the membrane needs to be improved, which will affect its practical application in oil-water separation. Summary of the invention

[0004] The purpose of the present invention is to provide a polysulfone composite oil-water separation membrane with surface modified ZIF-7-OH and a preparation method and application thereof. The method is simple and feasible, the raw material source is wide, and the product has excellent durability.

[0005] The present invention adopts a simple method of blending and non-solvent induced phase transformation to hydroxylate ZIF-7 particles, wherein the introduction of hydroxyl groups can couple the particles with hydrophobic polymers with siloxane groups and fix them on the membrane, thereby improving the stability of the particles on the membrane surface, increasing the roughness of the membrane surface, and constructing a super-hydrophobic polysulfone composite membrane through the synergistic effect of micro-nano rough structure and low surface energy materials. The membrane can efficiently separate oil-water emulsions stabilized by surfactants, has excellent self-cleaning performance, recyclability, high separation efficiency and anti-pollution, and has good application prospects in the field of oil-water separation.

[0006] The present invention proposes a polysulfone composite oil-water separation membrane with surface modified ZIF-7-OH and a preparation method thereof, and the technical scheme adopted is as follows:

[0007] A polysulfone composite oil-water separation membrane with surface modified ZIF-7-OH and a preparation method thereof, wherein a hydrophobic polymer is synthesized by free radical polymerization, and the hydrophobic polymer is blended with a polysulfone matrix to obtain a casting solution. A solution containing ZIF-7-OH nanoparticles is used as a coagulation bath, and in the non-solvent induced phase transformation process, the ZIF-7-OH nanoparticles can be coupled with a hydrophobic polymer with a siloxane group and fixed on the membrane surface, and finally a super-hydrophobic polysulfone composite membrane for efficient emulsion separation is obtained. The present invention hydroxylates the ZIF-7 particles and fixes them to the membrane surface through coupling, and the synergistic effect of the micro-nano rough structure and the low surface energy material not only gives the membrane super-hydrophobicity and excellent self-cleaning performance, but also enables the composite membrane to have efficient oil-water emulsion separation ability. The preparation method of the present invention is simple and feasible, has a wide source of raw materials, and has good separation performance. The obtained membrane material exhibits super-hydrophobic characteristics in the air, and can efficiently separate the oil-in-water emulsion stabilized by the surfactant. The specific steps are as follows:

[0008] (1) Prepare a hydrophobic polymer by free radical copolymerization and mix it with polysulfone: Dissolve 5-10 parts of monomer A, 0.1-3 parts of monomer B and 10-50 parts of solvent C in a round-bottom flask, then add initiator D to the solution, and carry out polymerization reaction at 60-85°C under argon or nitrogen protection for 7-20 hours to obtain a hydrophobic polymer. Dissolve the polysulfone and the hydrophobic polymer in solvent E, the mass ratio of polysulfone to hydrophobic polymer is 0.2-1.5, and the mass ratio of polysulfone to solvent E is 0.1-0.3, and stir at 60-85°C for 1-5 hours to obtain a reaction solution;

[0009] (2) dissolving zinc nitrate hexahydrate in solvent F, and then quickly adding it to an equal volume of solvent G containing benzimidazole and 2-hydroxybenzimidazole, wherein the molar ratio of 2-hydroxybenzimidazole to benzimidazole is 1-3, the mixed solution is reacted at 20-40° C. for 4-10 h, centrifuged, washed, and dried to obtain ZIF-7-OH;

[0010] (3) uniformly dispersing 1-20 wt % ZIF-7-OH in H solution to obtain a coagulation bath;

[0011] (4) The reaction solution in (1) is allowed to stand for degassing, and the membrane is scraped with a scraper, and the membrane is placed in (3) for phase inversion, thereby finally obtaining a polysulfone composite oil-water separation membrane with surface modified ZIF-7-OH.

[0012] The monomer A is one or more of trifluoroethyl methacrylate, hexafluoroethyl methacrylate, tridecafluoroethyl methacrylate, and perfluoroalkylethyl acrylate;

[0013] The monomer B is one or more of vinyl triethoxysilane, vinyl trimethoxysilane, vinyl triisopropoxysilane, and vinyl tri(β-methoxyethoxysilane);

[0014] The solvent C is one or more of dimethyl sulfoxide, N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, and ethanol;

[0015] The initiator D is one or more of azobisisobutyronitrile, diacyl peroxide, potassium persulfate, and ammonium persulfate;

[0016] The solvent E is one or more of N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dichloromethane, and chloroform;

[0017] The solvent F is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, methanol, ethanol, and deionized water;

[0018] The solvent G is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, methanol, ethanol, and deionized water;

[0019] The solvent H is one or more of methanol, ethanol and propylene glycol.

[0020] The scraping film parameters in step (4) of the present invention are: an ambient temperature of 20-30° C., a humidity of 30-50%, and a scraping film thickness of 100-300 μm.

[0021] The polysulfone composite oil-water separation membrane with surface modified ZIF-7-OH prepared by the invention and the preparation method thereof are used in the selective separation of oil-water mixture.

[0022] The polysulfone composite oil-water separation membrane with surface modified ZIF-7-OH prepared by the present invention and the preparation method thereof are used in the selective separation of emulsified oil-water mixture.

[0023] The polysulfone composite oil-water separation membrane with surface modified ZIF-7-OH prepared by the present invention has the following positive effects:

[0024] a. ZIF-7-OH particles can be stably fixed on the membrane surface, increasing the roughness of the membrane surface and improving the hydrophobicity of the membrane surface;

[0025] b. The water contact angle of the membrane surface is 162.9°, showing super hydrophobicity in the air and excellent oil-water emulsion separation performance;

[0026] c. The polysulfone composite membrane separates the oil-water emulsion containing surfactant and has a high separation flux;

[0027] d. Excellent cyclic stability. After multiple separation cycles, the superhydrophobic polysulfone composite membrane still maintains high oil-water separation efficiency;

[0028] e. Excellent self-cleaning and anti-pollution performance. Pollutants on the membrane surface can be carried away by falling water droplets. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The following is a further detailed description of the implementation method of the present invention in conjunction with the accompanying drawings.

[0030] Figure 1 is a schematic diagram of the preparation of hydrophobic polymers by free radical polymerization;

[0031] Figure 2 It is a schematic diagram of the preparation of a polysulfone composite oil-water separation membrane with surface modified ZIF-7-OH and its process;

[0032] Figure 3 Scanning electron micrographs of the surfaces of pure polysulfone membranes (a)-(c), polysulfone membranes modified with only hydrophobic polymers (d)-(f), composite polysulfone membranes (g)-(i), and ZIF-7-OH particles (j)-(l);

[0033] Figure 4 is the contact angle of water in air for pure polysulfone membrane (a), and (b) the contact angle of water in air for polysulfone composite membrane;

[0034] Figure 5 It is the process of pulling water from the polysulfone composite membrane in the air;

[0035] Figure 6 is the EDX spectrum of the polysulfone composite membrane;

[0036] Figure 7 (a) Schematic diagram of polysulfone composite membrane separation of emulsion, (b) optical microscope photos of polysulfone composite membrane before and after separation of n-heptane water-in-water emulsion, (c) separation flux of polysulfone composite membrane for different types of oil-in-water emulsions at 0.001MPa, (d) separation efficiency diagram, and polysulfone composite membrane for n-heptane water-in-water emulsion, (e, f) separation flux and separation efficiency diagrams of ten cycle separations;

[0037] Figure 8 This is a schematic diagram of the self-cleaning performance of polysulfone composite membrane. DETAILED DESCRIPTION

[0038] The present invention is further described below by means of specific examples, but the protection scope of the present invention is not limited thereto.

[0039] Embodiment 1:

[0040] A polysulfone composite oil-water separation membrane with surface modified ZIF-7-OH and a preparation method thereof (the preparation process is shown in the following figure) Figure 2 As shown), comprising the following process steps:

[0041] (1) Free radical copolymerization to prepare a hydrophobic polymer, which was mixed with polysulfone: 7 g of monomer hexafluoroethyl methacrylate, 0.5 g of monomer vinyltrimethoxysilane and 20.5 g of solvent N-methylpyrrolidone were dissolved in a round-bottom flask, and then the initiator diacyl peroxide was added to the solution. The polymerization reaction was carried out at a temperature of 70° C. under nitrogen protection for 10 h to obtain a hydrophobic polymer (the reaction flow diagram is shown in FIG. 2 ). Figure 1 The polysulfone and the hydrophobic polymer were dissolved in N,N-dimethylformamide, the mass ratio of the polysulfone to the hydrophobic polymer was 0.5, the mass ratio of the polysulfone to the solvent N,N-dimethylformamide was 0.15, and the mixture was stirred at 70° C. for 2 h to obtain a reaction solution;

[0042] (2) Dissolve zinc nitrate hexahydrate in N,N-dimethylacetamide solvent, then quickly add it to an equal volume of N,N-dimethylacetamide solvent containing benzimidazole and 2-hydroxybenzimidazole, the molar ratio of 2-hydroxybenzimidazole to benzimidazole being 1.5, and the mixture is reacted at 25° C. for 7 h, centrifuged, washed, and dried to obtain ZIF-7-OH (such as Figure 3 (jl) shown);

[0043] (3) 7 wt % ZIF-7-OH was uniformly dispersed in a methanol solution to obtain a coagulation bath;

[0044] (4) The reaction solution in (1) is allowed to stand for degassing, and the membrane is scraped with a scraper, and the membrane is placed in (3) for phase inversion. The scraping parameters are an ambient temperature of 25° C., a humidity of 40%, and a scraping thickness of 200 μm, and finally a polysulfone composite oil-water separation membrane with surface modified ZIF-7-OH is obtained.

[0045] The scanning electron microscopy image of the prepared polysulfone composite oil-water separation membrane with surface modified ZIF-7-OH is shown in Figure 3 (gi) as shown;

[0046] The contact angle of the prepared polysulfone composite oil-water separation membrane with surface modified ZIF-7-OH to water in air is as follows Figure 4 (b)

[0047] The pulling process of water droplets in the air of the prepared polysulfone composite oil-water separation membrane modified with ZIF-7-OH is shown in Figure 5 As shown, the superhydrophobic effect of the polysulfone composite oil-water separation membrane with surface modified ZIF-7-OH is demonstrated;

[0048] The EDX spectrum of the prepared surface modified ZIF-7-OH polysulfone composite oil-water separation membrane is shown in Figure 6 As shown;

[0049] Schematic diagram of the separation of emulsion by the prepared surface-modified ZIF-7-OH polysulfone composite oil-water separation membrane Figure 7 As shown in (a), optical microscope photos of n-heptane water emulsion before and after separation are shown in Figure 7 As shown in (b), the separation flux and separation efficiency of five different types of oil-in-water emulsions at 0.001 MPa are as follows Figure 7 (c, d) and the separation flux and separation efficiency of ten cycles of separation of n-heptane water emulsion are shown in Figure 7 (e, f);

[0050] The prepared surface modified ZIF-7-OH polysulfone composite oil-water separation membrane has self-cleaning effect on Sudan red and carbon powder pollutants. Figure 8 As shown in (a, b).

[0051] Embodiment 2:

[0052] A polysulfone composite oil-water separation membrane with surface modified ZIF-7-OH and a preparation method thereof (the preparation process is shown in the following figure) Figure 2 As shown), comprising the following process steps:

[0053] (1) Prepare a hydrophobic polymer by free radical copolymerization and mix it with polysulfone: Dissolve 5g of trifluoroethyl methacrylate, 0.3g of vinyl triethoxysilane and 11g of dimethyl sulfoxide in a round-bottom flask, then add the initiator azobisisobutyronitrile to the solution, and carry out polymerization at 60°C under argon protection for 7 hours to obtain a hydrophobic polymer. Dissolve the polysulfone and the hydrophobic polymer in N-methylpyrrolidone, the mass ratio of polysulfone to the hydrophobic polymer is 0.2, and the mass ratio of polysulfone to the solvent N-methylpyrrolidone is 0.1, and stir at 60°C for 1 hour to obtain a reaction solution;

[0054] (2) dissolving zinc nitrate hexahydrate in a solvent N,N-dimethylformamide, and then quickly adding it to an equal volume of N,N-dimethylformamide containing benzimidazole and 2-hydroxybenzimidazole, wherein the molar ratio of 2-hydroxybenzimidazole to benzimidazole is 1, the mixed solution is reacted at 20° C. for 5 h, centrifuged, washed, and dried to obtain ZIF-7-OH;

[0055] (3) 1 wt % ZIF-7-OH was uniformly dispersed in an ethanol solution to obtain a coagulation bath;

[0056] (4) The reaction solution in (1) is allowed to stand for degassing, and the membrane is scraped with a scraper, and the membrane is placed in (3) for phase inversion. The scraping parameters are an ambient temperature of 20° C., a humidity of 30%, and a scraping thickness of 100 μm, and finally a polysulfone composite oil-water separation membrane with surface modified ZIF-7-OH is obtained.

[0057] Embodiment 3:

[0058] A polysulfone composite oil-water separation membrane with surface modified ZIF-7-OH and a preparation method thereof (the preparation process is shown in the following figure) Figure 2 As shown), comprising the following process steps:

[0059] (1) Prepare a hydrophobic polymer by free radical copolymerization and mix it with polysulfone: 8g of monomer tridecafluoroethyl methacrylate, 1g of monomer vinyl triisopropoxysilane and 40g of solvent N,N-dimethylformamide are dissolved in a round-bottom flask, and then the initiator potassium persulfate is added to the solution. Under the protection of argon, the polymerization reaction is carried out at a temperature of 80°C for 15 hours to obtain a hydrophobic polymer. The polysulfone and the hydrophobic polymer are dissolved in the solvent N,N-dimethylacetamide, the mass ratio of polysulfone to hydrophobic polymer is 1, and the mass ratio of polysulfone to solvent N,N-dimethylacetamide is 0.2, and the mixture is stirred at 80°C for 4 hours to obtain a reaction solution;

[0060] (2) dissolving zinc nitrate hexahydrate in methanol solvent, and then quickly adding it to N,N-dimethylformamide solvent containing an equal volume of benzimidazole and 2-hydroxybenzimidazole, wherein the molar ratio of 2-hydroxybenzimidazole to benzimidazole is 2, the mixed solution is reacted at 30° C. for 9 h, centrifuged, washed, and dried to obtain ZIF-7-OH;

[0061] (3) 10 wt % ZIF-7-OH was uniformly dispersed in a methanol solution to obtain a coagulation bath;

[0062] (4) The reaction solution in (1) was allowed to stand for degassing, and the membrane was scraped with a scraper, and the membrane was placed in (3) for phase inversion. The scraping parameters were an ambient temperature of 30° C., a humidity of 50%, and a scraping thickness of 250 μm, and finally a polysulfone composite oil-water separation membrane with surface modified ZIF-7-OH was obtained.

[0063] Embodiment 4:

[0064] A polysulfone composite oil-water separation membrane with surface modified ZIF-7-OH and a preparation method thereof (the preparation process is shown in the following figure) Figure 2 As shown), comprising the following process steps:

[0065] (1) Prepare a hydrophobic polymer by free radical copolymerization and mix it with polysulfone: Dissolve 10g of monomer perfluoroalkylethyl acrylate, 1.5g of monomer vinyl tri(β-methoxyethoxysilane) and 40g of solvent ethanol in a round-bottom flask, then add the initiator ammonium persulfate to the solution, and carry out polymerization reaction at 85°C under argon protection for 20 hours to obtain a hydrophobic polymer. The polysulfone and the hydrophobic polymer are dissolved in the solvent dichloromethane, the mass ratio of polysulfone to the hydrophobic polymer is 1.5, and the mass ratio of polysulfone to the solvent dichloromethane is 0.3, and stir at 85°C for 5 hours to obtain a reaction solution;

[0066] (2) dissolving zinc nitrate hexahydrate in a solvent of methanol, and then quickly adding it to an equal volume of a solvent of ethanol containing benzimidazole and 2-hydroxybenzimidazole, wherein the molar ratio of 2-hydroxybenzimidazole to benzimidazole is 3, the mixed solution is reacted at 40° C. for 9 h, centrifuged, washed, and dried to obtain ZIF-7-OH;

[0067] (3) 20 wt % ZIF-7-OH was uniformly dispersed in a methanol solution to obtain a coagulation bath;

[0068] (4) The reaction solution in (1) is allowed to stand for degassing, and the membrane is scraped with a scraper, and the membrane is placed in (3) for phase inversion. The scraping parameters are an ambient temperature of 30° C., a humidity of 50%, and a scraping thickness of 300 μm, and finally a polysulfone composite oil-water separation membrane with surface modified ZIF-7-OH is obtained.

[0069] Comparative Example 1:

[0070] (1) dissolving polysulfone in solvent N-methylpyrrolidone, with the mass ratio of polysulfone to solvent N-methylpyrrolidone being 0.2, and stirring at 60° C. for 4 h;

[0071] (2) The solution obtained in (1) is allowed to stand for a period of time to remove bubbles, and then the membrane is scraped with a scraper and phase-inverted in a methanol coagulation bath to obtain a pure polysulfone membrane.

[0072] The scanning electron microscopy image of the prepared pure polysulfone membrane is shown in Figure 3 (ac) as shown;

[0073] The water contact angle of the prepared pure polysulfone membrane in air is as follows Figure 4 (a) shown.

[0074] Comparative Example 2:

[0075] (1) mixing a hydrophobic polymer obtained by free radical copolymerization with polysulfone: dissolving the polysulfone and the hydrophobic polymer in a solvent N-methylpyrrolidone, wherein the mass ratio of the polysulfone to the hydrophobic polymer is 1, and the mass ratio of the polysulfone to the solvent N-methylpyrrolidone is 0.2, and stirring at 60° C. for 4 h;

[0076] (2) The solution obtained in (1) is allowed to stand for a period of time to remove bubbles, and the membrane is scraped with a scraper, and phase inversion is performed in a methanol coagulation bath to obtain a polysulfone membrane modified only by a hydrophobic polymer.

[0077] The scanning electron microscopy image of the prepared polysulfone membrane modified only by the hydrophobic polymer is shown in Figure 3 (df) shown.

[0078] The above embodiments are not limitations of the present invention, and the present invention is not limited to the above embodiments. As long as the requirements of the present invention are met, they belong to the protection scope of the present invention.

[0079] The present invention hydroxylates ZIF-7 and fixes it to the membrane surface, wherein ZIF-7-OH particles can be coupled with a hydrophobic polymer with a siloxane group and fixed on the membrane, and a super-hydrophobic polysulfone composite membrane for efficient oil-water emulsion separation is finally obtained through the synergistic effect of micro-nano rough structure and low surface energy material. The preparation method of the present invention is simple and feasible, and the raw material source is extensive, and the separation flux is high. The obtained membrane material shows super-hydrophobic characteristics in the air, and can efficiently separate the oil-in-water emulsion containing a surfactant, and has excellent self-cleaning performance, recyclability and anti-pollution performance.

Claims

1. A polysulfone composite oil-water separation membrane with surface modified ZIF-7-OH, characterized in that: The method comprises coupling ZIF-7-OH particles with a hydrophobic polymer having a siloxane group and fixing the particles on a membrane to form a polysulfone composite oil-water separation membrane with surface modified ZIF-7-OH.

2. The method for preparing the polysulfone composite oil-water separation membrane with surface modified ZIF-7-OH as claimed in claim 1, characterized in that: The following steps are involved: (1) obtaining a hydrophobic polymer by free radical copolymerization, and mixing the hydrophobic polymer with polysulfone to obtain a reaction solution; (2) dissolving zinc nitrate hexahydrate in solvent F, then adding the mixture to solvent G containing benzimidazole and 2-hydroxybenzimidazole for reaction, centrifuging, washing, and drying to obtain ZIF-7-OH; (3) uniformly dispersing ZIF-7-OH in solvent H to obtain a coagulation bath; (4) The reaction solution obtained in step (1) is allowed to stand for degassing, and the membrane is scraped with a scraper, and the membrane is placed in the coagulation bath in step (3) for phase inversion, thereby finally obtaining a polysulfone composite oil-water separation membrane with surface modified ZIF-7-OH.

3. The method for preparing the polysulfone composite oil-water separation membrane with surface modified ZIF-7-OH as claimed in claim 2, characterized in that: In step (1), a hydrophobic polymer is obtained by free radical copolymerization, and the hydrophobic polymer is mixed with polysulfone to obtain a reaction solution, which specifically comprises: Dissolve monomer A, monomer B and solvent C in a reactor, then add initiator D to the solution, perform polymerization at 60-85° C. under argon or nitrogen protection, and the reaction time is 7-20 hours to obtain a hydrophobic polymer, then dissolve the hydrophobic polymer and polysulfone in solvent E, and stir at 60-85° C. for 1-5 hours to obtain a reaction solution; Wherein, the monomer A is one or more of trifluoroethyl methacrylate, hexafluoroethyl methacrylate, tridecafluoroethyl methacrylate, and perfluoroalkylethyl acrylate; The monomer B is one or more of vinyl triethoxysilane, vinyl trimethoxysilane, vinyl triisopropoxysilane, and vinyl tri(β-methoxyethoxysilane); The solvent C is one or more of dimethyl sulfoxide, N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, and ethanol; The initiator D is one or more of azobisisobutyronitrile, diacyl peroxide, potassium persulfate, and ammonium persulfate; The solvent E is one or more of N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dichloromethane and chloroform.

4. The method for preparing the polysulfone composite oil-water separation membrane with surface modified ZIF-7-OH as claimed in claim 3, characterized in that: In step (1), the mass ratio of the polysulfone to the hydrophobic polymer is 0.2-2:1; the mass ratio of the polysulfone to the solvent E is 0.1-0.5:1 respectively; The mass ratio of monomer A:monomer B:solvent C is 5-10: 0.1-3：10-50。 5. The method for preparing the polysulfone composite oil-water separation membrane with surface modified ZIF-7-OH as claimed in claim 2, characterized in that: In step (2), the solvent F is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, methanol, ethanol, and deionized water; The solvent G is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, methanol, ethanol, and deionized water.

6. The method for preparing the polysulfone composite oil-water separation membrane with surface modified ZIF-7-OH as claimed in claim 2, characterized in that: In step (2), the molar ratio of 2-hydroxybenzimidazole to benzimidazole is 1-3:1; The reaction temperature is 20-40°C, and the reaction time is 4-10h.

7. The method for preparing the polysulfone composite oil-water separation membrane with surface modified ZIF-7-OH as claimed in claim 2, characterized in that: In step (3), the solvent H is one or more of methanol, ethanol, and propylene glycol; The content of ZIF-7-OH in the coagulation bath is 1-20 wt %.

8. The method for preparing the polysulfone composite oil-water separation membrane with surface modified ZIF-7-OH as claimed in claim 2, characterized in that: In step (4), the scraping parameters are as follows: an ambient temperature of 20-30° C., a humidity of 30-50%, and a scraping thickness of 100-300 μm.

9. Use of the polysulfone composite oil-water separation membrane with surface modified ZIF-7-OH as claimed in claim 1 in the selective separation of oil-water mixture.

10. Use of the polysulfone composite oil-water separation membrane with surface modified ZIF-7-OH as claimed in claim 1 in the selective separation of emulsified oil-water mixture.

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