An oil-water separation membrane, its preparation method and application

Abstract

This disclosure belongs to the field of water treatment technology, and provides an oil-water separation membrane, its preparation method, and its application. Preparation method: Prepare negatively charged COFs powder; dissolve the COFs powder and mix it with polyethersulfone and polyethylene glycol to form a casting solution; dissolve polyethyleneimine in water to prepare a coagulation bath; scrape the casting solution onto a glass plate to form a liquid film, and place it in the coagulation bath to solidify into a membrane. The oil-water separation membrane prepared according to the above method is also disclosed, as well as its application in oil-water separation. The polyethersulfone / COFs interface and COFs channels within the separation membrane provide a large amount of confined space, optimizing the mass transfer mechanism within the membrane. The positively charged PEI enhances the segregation of hydrophilic and negatively charged groups, assembling a selective separation layer in situ during phase transformation. The ionic groups enriched on the membrane surface generate strong hydration, endowing the membrane with superoleophobic and low-adhesion properties underwater, and strengthening the antifouling mechanism of the membrane surface.

Description

Technical Field

[0001] This disclosure relates to the field of water treatment technology, and in particular to an oil-water separation membrane, its preparation method, and its application. Background Art

[0002] Oily wastewater is widely present in industrial production processes such as oil extraction and refining. It is characterized by its wide range of sources, significant hazards, and complex composition, making it a relatively difficult type of wastewater to treat. Developing efficient oil-water separation technologies to achieve deep treatment and resource recovery of oily wastewater is of great significance for the development of a green petrochemical industry. Compared to traditional oil-water separation technologies (air flotation, flocculation, adsorption, etc.), membrane separation technology has low energy consumption and high separation efficiency, and has broad application prospects in the field of oily wastewater treatment. Research on high-performance oil-water separation membrane materials currently faces two common key problems: low membrane permeate flux and severe membrane fouling. Oil droplets easily adhere to and spread on the membrane surface, causing severe and difficult-to-clean fouling, leading to a sharp decrease in membrane flux, reduced separation efficiency, and shortened service life, while also increasing overall operating costs.

[0003] Therefore, it is necessary to provide a separation membrane with underwater superoleophobic and antifouling properties. Summary of the Invention

[0004] This disclosure provides an oil-water separation membrane, its preparation method, and its application, to at least solve the above-mentioned technical problems existing in the prior art.

[0005] According to a first aspect of this disclosure, a method for preparing an oil-water separation membrane is provided, comprising the following steps:

[0006] S1: Mix the amino monomer with a solution of brominated alkylpyridine to prepare solution A; mix the trialdehyde phloroglucinol with dichloromethane to prepare solution B; mix solution A and solution B, precipitate, and filter to obtain negatively charged COFs (covalent organic framework) powder;

[0007] S2: Dissolve the COFs powder prepared in step S1 and mix it with polyethersulfone and polyethylene glycol to form a casting solution; the mass ratio of the COFs powder to the polyethylene glycol is 0.1-3%;

[0008] S3: Polyethyleneimine is dissolved in water to prepare a coagulation bath; in the coagulation bath, the concentration of polyethyleneimine is 0-10 g / L;

[0009] S4: The casting liquid prepared in step S2 is scraped onto a glass plate to form a liquid film, and then placed into the coagulation bath prepared in step S3 to solidify into a film, thus obtaining the oil-water separation membrane.

[0010] In one embodiment, in the brominated alkylpyridine solution of step S1, the brominated alkylpyridine is selected from at least one of hexadecylpyridine bromide and dodecylpyridine bromide.

[0011] In a preferred embodiment, the brominated alkylpyridine is selected from hexadecylpyridine bromide.

[0012] In one embodiment, the brominated alkylpyridine solution in step S1 is prepared by dissolving brominated alkylpyridine in water, wherein the concentration of the brominated alkylpyridine is 1 to 1.5 mg / mL.

[0013] In a preferred embodiment, the concentration of the brominated alkylpyridine is 1 mg / mL.

[0014] In one embodiment, the amino monomer is selected from any one of Pa-PO3H2, Pa-SO3H, and Pa-CO2H.

[0015] In one embodiment, the concentration of the amino monomer is 1.5 to 2.0 mg / mL.

[0016] In a preferred embodiment, the concentration of the amino monomer is 1.6 mg / mL.

[0017] In one embodiment, step S1 involves mixing the amino monomer with the brominated alkylpyridine solution at 500–800 rpm to obtain solution A.

[0018] In a preferred embodiment, step S1 involves mixing the amino monomer with the brominated alkylpyridine solution at 500 rpm to obtain solution A.

[0019] In one embodiment, the concentration of the trialdehyde phloroglucinol is 8–10 mg / mL.

[0020] In a preferred embodiment, the concentration of the trialdehyde phloroglucinol is 9 mg / mL.

[0021] In one embodiment, step S1 involves mixing solution A and solution B at room temperature for 10-15 minutes, precipitating the solid with ethanol, filtering to obtain negatively charged COFs powder, and purifying with methanol.

[0022] In one embodiment, the specific steps of dissolving the COFs powder in step S2 include: dispersing the COFs powder in N,N-dimethylformamide solvent.

[0023] In one embodiment, the mass ratio of the polyethersulfone to the N,N-dimethylformamide in step S2 is 1:(3.5-10).

[0024] In one embodiment, the polyethyleneimine has an average molecular weight of 70,000 to 75,000 and a solid content of 45% to 55%.

[0025] In a preferred embodiment, the polyethyleneimine has an average molecular weight of 70,000 and a solid content of 50%.

[0026] In one embodiment, in step S3, when the concentration of the polyethyleneimine is 0, the coagulation bath is water.

[0027] In a preferred embodiment, the concentration of polyethyleneimine in step S3 is 1 to 10 g / L.

[0028] In a more preferred embodiment, the concentration of polyethyleneimine in step S3 is 5 g / L.

[0029] In one embodiment, the thickness of the liquid film in step S4 is 200–250 μm.

[0030] In a preferred embodiment, the thickness of the liquid film in step S4 is 200 μm.

[0031] In one embodiment, step S4 involves scraping the casting liquid onto the glass plate to form a liquid film, and then placing it in the coagulation bath for 5-10 minutes to solidify it into a film.

[0032] In one embodiment, after the solidified film is formed in step S4, the solid film is removed from the glass plate and then soaked in water for 12 to 24 hours to obtain the oil-water separation membrane.

[0033] According to a second aspect of this disclosure, an oil-water separation membrane prepared according to the above-described preparation method is provided.

[0034] According to a third aspect of this disclosure, the above-mentioned oil-water separation membrane is provided for oil-water separation in light oil-water mixtures, heavy oil-water mixtures, water-in-oil emulsions, and oil-in-water emulsions.

[0035] According to one possible implementation of this disclosure, at least the following beneficial effects are achieved:

[0036] To address existing technologies, constructing a super-strong hydration layer on the membrane surface is an effective antifouling strategy. This disclosure proposes a separation membrane with underwater superoleophobic and antifouling properties prepared using an electrostatically enhanced reactive surface segregation method. By introducing COFs materials as modifiers, the membrane surface and pore structure are modified, while simultaneously improving the membrane's mechanical strength and introducing additional pore structures.

[0037] This disclosure discloses a rapid synthesis of negatively charged COFs via emulsion polymerization, using polymers as the main membrane material and COFs as a modifier. The polyethersulfone / COF interface and COF channels within the membrane provide a large amount of confined space, optimizing the mass transfer mechanism within the membrane.

[0038] Furthermore, due to the strong electrostatic force, the positively charged polyethyleneimine (PEI) in the coagulation bath enhances the segregation of hydrophilic and negatively charged groups in the casting solution, facilitating the in-situ assembly of a selective separation layer during phase transformation. This process is characterized by its simple operation, excellent membrane performance, and ease of large-scale preparation. The ionic groups enriched on the membrane surface generate strong hydration, endowing the membrane with superoleophobic and low-adhesion properties underwater, and strengthening the antifouling mechanism of the membrane surface.

[0039] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present disclosure, nor are they intended to limit the scope of the present disclosure. Other features of the present disclosure will become readily understood through the following description. Attached Figure Description

[0040] The above and other objects, features and advantages of the exemplary embodiments of the present disclosure will become readily understood by reading the detailed description below with reference to the accompanying drawings, in which several embodiments of the present disclosure are shown by way of example and not limitation, wherein:

[0041] In the drawings, the same or corresponding reference numerals denote the same or corresponding parts.

[0042] Figure 1 The X-ray diffraction pattern of the TpPa-COOH powder in Example 1 of this disclosure is shown;

[0043] Figure 2 A cross-sectional scanning electron microscope image of the oil-water separation membrane 1 in Embodiment 1 of this disclosure is shown;

[0044] Figure 3 A cross-sectional scanning electron microscope image of the polyethersulfone film in the comparative example of this disclosure is shown;

[0045] Figure 4 The permeation flux statistics of the separation membranes prepared in Examples 1-7 and the comparative examples of this disclosure are shown;

[0046] Figure 5 The flux recovery rate of the separation membranes prepared in Examples 1-7 and the comparative examples of this disclosure is shown in the figure. Detailed Implementation

[0047] To make the purposes, features, and advantages of the present disclosure more apparent and understandable, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present disclosure, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present disclosure without creative work shall fall within the scope of protection of the present disclosure.

[0048] Currently, covalent organic frameworks (COFs) are developing rapidly, possessing characteristics such as large specific surface area, high-density functional groups, and high mechanical properties. They offer the following potential advantages in membrane separation: 1) COFs have high porosity, providing abundant transport pathways for intramembrane mass transfer and achieving high permeability; 2) COFs have uniform pore size, allowing for precise control of pore size through monomer structural design, achieving high selectivity; 3) COFs have a regular pore structure with high-density, uniformly distributed, designable functionalized sites on the walls, enabling the design of low-resistance walls and rapid molecular transport. These characteristics make COFs ideal candidate materials for preparing high-performance oil-water separation membranes; however, research on COFs in oil-water separation has been limited. Therefore, this disclosure provides a separation membrane with underwater superoleophobic and antifouling properties prepared using an electrostatically enhanced reactive surface segregation method. Specific examples are analyzed below.

[0049] Example 1

[0050] In this embodiment, an oil-water separation membrane 1 was prepared, and the specific process is as follows:

[0051] (1) Add 15 mL of 1 mg / mL hexadecylpyridine bromide aqueous solution to a round-bottom flask; add 24 mg of amino monomer (2,5-diaminobenzoic acid) to the above hexadecylpyridine bromide aqueous solution and stir at 500 rpm to dissolve to obtain solution A; dissolve 31.5 mg of trialdehyde phloroglucinol in 3.5 mL of dichloromethane by ultrasonication to obtain solution B; mix solution A and solution B, stir at room temperature for 10 min, precipitate the solid with ethanol after the reaction, filter to obtain solid powder, and purify with methanol to obtain a negatively charged covalent organic framework (COFs) modifier, denoted as TpPa-COOH.

[0052] (2) Add 10 mg of TpPa-COOH powder obtained in step (1) to 13.4 g of N,N-dimethylformamide solvent and disperse evenly. Then add 3.6 g of polyethersulfone (BASF 6020, industrial grade) and 3 g of polyethylene glycol (molecular weight 600) and stir to dissolve to form a casting solution.

[0053] (3) After cooling the casting solution prepared in step (2) to room temperature, pour it onto a glass plate and scrape it into a liquid film of about 200 μm thickness. Then place it in a coagulation bath of deionized water at 25°C and solidify it into a film for 5 minutes. After removing it from the glass plate, soak it in deionized water for 24 hours to obtain oil-water separation membrane 1.

[0054] The XRD pattern of the above TpPa-COOH powder is as follows: Figure 1 As shown, Figure 1 The results showed that the TpPa-COOH powder exhibited sharp diffraction peaks at 4.7°, 8.2°, 12.8° and 27.1°, confirming the successful synthesis of TpPa-COOH.

[0055] The cross-sectional scanning electron microscope image of oil-water separation membrane 1 is shown below. Figure 2 As shown, Figure 2 The membrane surface exhibits a porous structure, with a finger-like pore structure in cross-section. The membrane's pure water flux is 450 Lm³. -2 h -1 bar -1 In oil-water emulsion separation applications (0.1 wt% pump oil, 0.01 wt% Tween 80, 99.89 wt% water), membrane permeation flux data can be found in [reference needed]. Figure 4 Its value is 323Lm -2 h -1 bar -1 The retention rate was 99.5%. After rinsing with deionized water for 10 minutes, the antifouling index (FRR) was 89% (see...). Figure 5 The flux recovery rate (which represents the antifouling index) shows that the introduction of TpPa-COOH improves the membrane's antifouling performance.

[0056] Comparative Example

[0057] This comparative example prepared a polyethersulfone membrane. The difference from Example 1 is that COFs were not introduced into the casting solution in this comparative example. The specific process is as follows:

[0058] 3.6 g of polyethersulfone (BASF 6020, industrial grade), 3 g of polyethylene glycol (molecular weight 600), and 13.4 g of N,N-dimethylformamide were added to a round-bottom flask and heated and stirred in a 60°C water bath for 6 h. The mixture was then allowed to stand for 12 h to remove bubbles, yielding a casting solution. The casting solution was cooled to room temperature, poured onto a glass plate, and scraped to form a liquid film approximately 200 μm thick. This film was then placed in a 25°C deionized water coagulation bath and allowed to solidify for 5 min. After being removed from the glass plate, the film was soaked in deionized water for 24 h to obtain the polyethersulfone membrane.

[0059] The cross-sectional scanning electron microscope image of the polyethersulfone film is shown below. Figure 3 As shown, Figure 3The membrane exhibits a porous surface structure with an asymmetrical cross-section. The top surface has a dense skin layer, while the secondary layer contains finger-like pores that provide support. The membrane's pure water flux is 366 L / m³. -2 h -1 bar -1 In oil-water emulsion separation applications (0.1 wt% pump oil, 0.01 wt% Tween 80, 99.89 wt% water), membrane permeation flux data can be found in [reference needed]. Figure 4 Its value is 293Lm -2 h -1 bar -1 The retention rate was 99.2%. After rinsing with deionized water for 10 minutes, the antifouling index (FRR) was 76% (see...). Figure 5 The results show that the polyethersulfone membrane has weak antifouling properties.

[0060] Example 2

[0061] In this embodiment, an oil-water separation membrane 2 was prepared. The specific process was basically the same as in Example 1, except that the content of TpPa-COOH powder in step (2) was changed to 30mg.

[0062] The results showed that the surface of oil-water separation membrane 2 had a porous structure, and the cross-section exhibited a finger-like pore structure. The membrane's pure water flux was 528 Lm. -2 h -1 bar -1 For applications involving the separation of oil-water emulsions (0.1 wt% pump oil, 0.01 wt% Tween 80, 99.89 wt% water), membrane permeation flux data can be found in [reference needed]. Figure 4 Its value is 368Lm -2 h -1 bar -1 The retention rate was 99.5%. After rinsing with deionized water for 10 minutes, the antifouling index (FRR) was 91% (see...). Figure 5 The results show that the introduction of TpPa-COOH improves the membrane's antifouling performance.

[0063] Example 3

[0064] In this embodiment, an oil-water separation membrane 3 was prepared. The specific process was basically the same as in Example 1, except that the content of TpPa-COOH powder in step (2) was changed to 50 mg.

[0065] The results showed that the surface of the oil-water separation membrane 3 had a porous structure, and the cross-section exhibited a finger-like pore structure. The membrane's pure water flux was 412 Lm. -2 h -1 bar -1For applications involving the separation of oil-water emulsions (0.1 wt% pump oil, 0.01 wt% Tween 80, 99.89 wt% water), membrane permeation flux data can be found in [reference needed]. Figure 4 Its value is 210Lm -2 h -1 bar -1 The retention rate was 99.7%. After rinsing with deionized water for 10 minutes, the antifouling index (FRR) was 90% (see...). Figure 5 The results show that the introduction of TpPa-COOH improves the membrane's antifouling performance.

[0066] Example 4

[0067] In this embodiment, an oil-water separation membrane 4 was prepared. The specific process was basically the same as in Example 1, except that the content of TpPa-COOH powder in step (2) was changed to 70 mg.

[0068] The results showed that the surface of oil-water separation membrane 4 had a porous structure, and the cross-section exhibited a finger-like pore structure. The membrane's pure water flux was 266 Lm. -2 h -1 bar -1 For applications involving the separation of oil-water emulsions (0.1 wt% pump oil, 0.01 wt% Tween 80, 99.89 wt% water), membrane permeation flux data can be found in [reference needed]. Figure 4 Its value is 158Lm -2 h -1 bar -1 The retention rate was 99.6%. After rinsing with deionized water for 10 minutes, the antifouling index (FRR) was 90% (see...). Figure 5 The results show that the introduction of TpPa-COOH improves the membrane's antifouling performance.

[0069] Example 5

[0070] In this embodiment, an oil-water separation membrane 5 was prepared, and the specific process is as follows:

[0071] (1) Add 15 mL of 1 mg / mL hexadecylpyridine bromide aqueous solution to a round-bottom flask; add 24 mg of amino monomer (2,5-diaminobenzoic acid) to the above hexadecylpyridine bromide aqueous solution and stir at 500 rpm to dissolve to obtain solution A; dissolve 31.5 mg of trialdehyde phloroglucinol in 3.5 mL of dichloromethane by ultrasonication to obtain solution B; mix solution A and solution B, stir at room temperature for 10 min, precipitate the solid with ethanol after the reaction, filter to obtain solid powder, and purify with methanol to obtain a negatively charged covalent organic framework (COFs) modifier, denoted as TpPa-COOH.

[0072] (2) Add 30 mg of TpPa-COOH powder obtained in step (1) to 13.4 g of N,N-dimethylformamide solvent and disperse evenly. Then add 3.6 g of polyethersulfone (BASF 6020, industrial grade) and 3 g of polyethylene glycol (molecular weight 600) and stir to dissolve to form a casting solution.

[0073] (3) Add polyethyleneimine (PEI, with an average molecular weight of 70,000 and a solid content of 50%) to 1L of deionized water and stir until fully dissolved to obtain a 1g / L positively charged polyethyleneimine coagulation bath.

[0074] (4) After cooling the casting liquid prepared in step (2) to room temperature, pour it onto a glass plate and scrape it into a liquid film of about 200 μm thickness. At a constant temperature of 25°C, place it in the polyethyleneimine coagulation bath prepared in step (3) and solidify it into a film for 5 minutes. After removing the solid film from the glass plate, soak it in deionized water for 24 hours to obtain the oil-water separation membrane 5.

[0075] The results showed that the surface of oil-water separation membrane 5 had a porous structure, and the cross-section exhibited a finger-like pore structure. The membrane's pure water flux was 552 Lm. -2 h -1 bar -1 For applications involving the separation of oil-water emulsions (0.1 wt% pump oil, 0.01 wt% Tween 80, 99.89 wt% water), membrane permeation flux data can be found in [reference needed]. Figure 4 Its value is 393Lm -2 h -1 bar -1 The retention rate was 99.6%. After rinsing with deionized water for 10 minutes, the antifouling index (FRR) was 92% (see...). Figure 5 The results show that the introduction of TpPa-COOH and PEI improves the antifouling performance of the membrane.

[0076] Example 6

[0077] In this embodiment, an oil-water separation membrane 6 was prepared. The specific process was basically the same as in Example 5, except that the concentration of the positively charged polyethyleneimine coagulation bath in step (3) was changed to 5 g / L.

[0078] The results showed that the surface of oil-water separation membrane 6 had a porous structure, and the cross-section exhibited a finger-like pore structure. The membrane's pure water flux was 592 Lm³. -2 h -1 bar -1 For applications involving the separation of oil-water emulsions (0.1 wt% pump oil, 0.01 wt% Tween 80, 99.89 wt% water), membrane permeation flux data can be found in [reference needed]. Figure 4 Its value is 454Lm -2 h -1 bar-1 The retention rate was 100%. After rinsing with deionized water for 10 minutes, the antifouling index (FRR) was 95% (see...). Figure 5 The results show that the introduction of TpPa-COOH and PEI improves the antifouling performance of the membrane.

[0079] Example 7

[0080] In this embodiment, an oil-water separation membrane 7 was prepared. The specific process was basically the same as in Example 5, except that the concentration of the positively charged polyethyleneimine coagulation bath in step (3) was changed to 10 g / L.

[0081] The results showed that the surface of the oil-water separation membrane 7 had a porous structure, and the cross-section exhibited a finger-like pore structure. The membrane's pure water flux was 446 Lm. -2 h -1 bar -1 For applications involving the separation of oil-water emulsions (0.1 wt% pump oil, 0.01 wt% Tween 80, 99.89 wt% water), membrane permeation flux data can be found in [reference needed]. Figure 4 Its value is 348Lm -2 h -1 bar -1 The retention rate was 100%. After rinsing with deionized water for 10 minutes, the antifouling index (FRR) was 95% (see...). Figure 5 The results show that the introduction of TpPa-COOH and PEI improves the antifouling performance of the membrane.

[0082] In summary, the preparation method provided in this disclosure can form a membrane in one step. The antifouling structure layer on the membrane surface can be controlled by adjusting the amount of TpPa-COOH added to the casting solution and the concentration of polyethyleneimine in the coagulation bath. The addition of polyethyleneimine in the coagulation bath enhances the antifouling performance of the membrane surface. As the concentration of polyethyleneimine increases, the permeate flux of the oil-water separation membrane first increases and then decreases, while the rejection rate remains basically unchanged, indicating improved antifouling performance. The oil-water separation membrane 6 prepared in Example 6 achieves the optimal overall performance.

[0083] It should be understood that the various forms of processes shown above can be used to rearrange, add, or delete steps. For example, the steps described in this disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this disclosure can be achieved, and this is not limited herein.

[0084] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this disclosure, "a plurality of" means two or more, unless otherwise explicitly specified.

[0085] The above description is merely a specific embodiment of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A method for preparing an oil-water separation membrane, characterized in that, The following steps are involved: S1: Mix an amino monomer with a brominated alkylpyridine solution at 500-800 rpm to prepare solution A; mix trialdehyde phloroglucinol with dichloromethane to prepare solution B; mix solution A and solution B at room temperature for 10-15 min, precipitate the solid with ethanol, filter to obtain negatively charged COFs powder, and purify with methanol; the amino monomer is selected from any one of Pa-PO3H2, Pa-SO3H, and Pa-CO2H. S2: Dissolve the COFs powder prepared in step S1 and mix it with polyethersulfone and polyethylene glycol to form a casting solution; the mass ratio of the COFs powder to the polyethylene glycol is 0.1~3%; S3: Polyethyleneimine is dissolved in water to prepare a coagulation bath; in the coagulation bath, the concentration of polyethyleneimine is 1~10 g / L; S4: The casting liquid prepared in step S2 is scraped onto a glass plate to form a liquid film, and then placed into the coagulation bath prepared in step S3 to solidify into a film, thus obtaining the oil-water separation membrane.

2. The preparation method according to claim 1, characterized in that, In the brominated alkylpyridine solution described in step S1, the brominated alkylpyridine is selected from at least one of hexadecylpyridine bromide and dodecylpyridine bromide.

3. The preparation method according to claim 1, characterized in that, The specific steps of dissolving the COFs powder in step S2 include: dispersing the COFs powder in N,N-dimethylformamide solvent.

4. The preparation method according to claim 3, characterized in that, In step S2, the mass ratio of polyethersulfone to N,N-dimethylformamide is 1:(3.5~10).

5. The preparation method according to claim 1, characterized in that, The polyethyleneimine has an average molecular weight of 70,000 to 75,000 and a solid content of 45% to 55%.

6. The preparation method according to claim 1, characterized in that, The thickness of the liquid film in step S4 is 200~250μm.

7. The preparation method according to claim 1, characterized in that, Step S4 involves scraping the casting liquid onto the glass plate to form a liquid film, and then placing it in the coagulation bath for 5-10 minutes to solidify into a film.

8. The preparation method according to claim 1, characterized in that, In step S4, after the solidified film is formed, the solid film is removed from the glass plate and then soaked in water for 12-24 hours to obtain the oil-water separation membrane.

9. An oil-water separation membrane prepared by any one of claims 1 to 8.

10. The application of the oil-water separation membrane of claim 9 in the separation of oil and water in light oil-water mixtures, heavy oil-water mixtures, water-in-oil emulsions, and oil-in-water emulsions.

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