Two-dimensional porous f-ce nanosheet / pva hybrid matrix membrane and preparation method and application thereof

Abstract

The application discloses a two-dimensional porous F-Ce nanosheet / PVA mixed matrix membrane and a preparation method and application thereof, and belongs to the technical field of pervaporation membrane separation. The application adds a sodium fluoride aqueous solution into a cerium acetate aqueous solution, and after stirring reaction, centrifugal washing and freeze-drying treatment, a two-dimensional porous F-Ce nanosheet is obtained; the PVA is dissolved in deionized water at 80-95 DEG C, a crosslinking agent and a catalyst are added in sequence and uniformly mixed, and then the solution is reduced to room temperature; the two-dimensional porous F-Ce nanosheet is introduced into the PVA solution, and after standing and defoaming, the two-dimensional porous F-Ce nanosheet is coated on a porous support base, and after heat treatment, the target mixed matrix membrane is obtained. The application aims at introducing the uniformly dispersed two-dimensional porous F-Ce nanosheet into the PVA matrix, solving the problems of poor anti-swelling and poor separation performance of the PVA membrane, optimizing the PVA chain segment arrangement, strengthening the water molecule transmission in the membrane, and realizing the controllable preparation of the mixed matrix membrane with high permeability and high selectivity.

Description

Technical Field

[0001] This invention relates to a two-dimensional porous F-Ce nanosheet / PVA hybrid matrix membrane, its preparation method and application, belonging to the field of pervaporation membrane separation technology. Background Technology

[0002] ε-Caprolactam (CPL) is an important organic chemical raw material, mainly used in the production of high-quality polyamide fibers and nylon, which is crucial to the development of the national economy. Industrial production of CPL mainly includes the cyclohexanone-hydroxylamine process, the toluene oxidation process, and the cyclohexane photonitrosation process. The crude product contains 65-70 wt% CPL, with the remainder mainly consisting of ammonium salts and water. CPL is a heat-sensitive substance with a higher boiling point than water; the presence of water inhibits the growth of the CPL polymerization chain, severely affecting the quality of chemical fiber production. Therefore, efficient dehydration of CPL is a crucial step. Traditional CPL dehydration technologies, such as triple-effect evaporation, crystallization, and melt crystallization, suffer from drawbacks such as complex processes and low mass transfer efficiency. In contrast, pervaporation membrane separation technology offers advantages such as high separation efficiency, low energy consumption, simple operation, environmental friendliness, and cleanliness, and the process is not limited by vapor-liquid equilibrium. It is widely used in the field of organic matter dehydration, and high-performance separation membrane materials are key components of pervaporation technology.

[0003] Polyvinyl alcohol (PVA) is one of the most widely used membrane materials in the industrial application of pervaporation dehydration of organic matter due to its low cost, strong film-forming properties, and excellent stability. However, existing PVA membranes generally suffer from a "trade-off" problem of incompatibility between permeability and selectivity, which limits their industrial applications. To address this issue, researchers have introduced zeolites, molecular sieves, and other inorganic fillers into the PVA matrix to prepare mixed matrix membranes (MMMs) to improve membrane permeate flux and separation factor. Lin et al. (Desalination, 2012, 285, 39-45) introduced nano-silica into PVA membranes to prepare mixed matrix membranes with enhanced caprolactam dehydration performance. However, these traditional inorganic fillers, such as zeolites and molecular sieves, have poor interfacial compatibility with the polymer matrix, are prone to agglomeration, and easily form non-selective defects during membrane preparation, leading to membrane selectivity degradation. Therefore, there is an urgent need to develop novel mixed matrix membranes filled with inorganic porous materials to further improve membrane separation performance and stability. Summary of the Invention

[0004] The purpose of this invention is to provide a highly efficient and stable two-dimensional porous nanosheet / PVA hybrid matrix membrane and its preparation method, for pervaporation dehydration of caprolactam, thereby improving the permeability, selectivity and stability of the membrane material in pervaporation dehydration of caprolactam.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] This invention provides a two-dimensional porous F-Ce nanosheet / PVA hybrid matrix membrane. Two-dimensional porous F-Ce nanosheets are introduced into a polyvinyl alcohol (PVA) solution to obtain a casting solution, which is then coated onto a porous support substrate to prepare a thin and defect-free two-dimensional porous F-Ce nanosheet / PVA hybrid matrix membrane for pervaporation and dehydration of caprolactam.

[0007] The polyvinyl alcohol (PVA) is selected from one or more of PVA 105, PVA 117, PVA 124, PVA 1788, PVA 1792, PVA 1799, and PVA 2488;

[0008] The porous support substrate is made of any one of polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyacrylonitrile, polysulfone, polyethersulfone, or ceramic, and its shape is flat, tubular, or hollow fiber.

[0009] This invention provides a method for preparing a two-dimensional porous F-Ce nanosheet / PVA hybrid matrix membrane, the specific preparation steps of which include:

[0010] 1) Dissolve cerium acetate in deionized water treated with high-purity nitrogen to obtain solution 1, with a concentration of 1-5 g·L⁻¹. -1 ;

[0011] 2) Dissolve sodium fluoride in deionized water treated with high-purity nitrogen to obtain solution 2, with a concentration of 0.5–3 g·L⁻¹. -1 ;

[0012] 3) Add solution 2 dropwise to solution 1 and stir at room temperature for 1 to 12 hours to obtain a suspension; wherein the volume ratio of solution 1 to solution 2 is 2:1 to 5:1;

[0013] 4) The suspension obtained in step 3) is centrifuged, washed, and freeze-dried to obtain the two-dimensional porous F-Ce nanosheets;

[0014] 5) Dissolve PVA in deionized water at 80–95℃ to obtain solution 3 with a concentration of 20–50 g·L⁻¹. -1 ;

[0015] 6) Add a crosslinking agent to solution 3 and stir for 10-60 minutes to obtain solution 4;

[0016] The crosslinking agent is one or more selected from boric acid, glutaraldehyde, maleic acid, maleic acid, dimethylol urea, trimethylol melamine, sulfonated succinic acid, 4-sulfophthalic acid, and polyacrylic acid-2-acrylamide-2-methylpropane sulfonic acid copolymer; the mass ratio of the crosslinking agent to the PVA is 0.05:1 to 0.5:1.

[0017] 7) Take 0.1–2 mol L -1 The catalyst was added dropwise to solution 4, the pH was adjusted to 1-5, stirring was continued for 3-6 hours, and after heating was stopped, the solution was cooled to room temperature to obtain solution 5.

[0018] The catalyst is either sulfuric acid or hydrochloric acid.

[0019] 8) Add 0.1–1 mol L to solution 5 -1 Alkaline aqueous solution, adjust pH to 7-12, and continue stirring for 10 min-6 h to obtain solution 6;

[0020] The alkaline substance is one or more of the following: sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium amino acid, ammonia, ethanolamine, diethanolamine, and triethylamine.

[0021] 9) The two-dimensional porous F-Ce nanosheets obtained in step 4) are introduced into the solution 6, ultrasonically dispersed, and allowed to stand to remove bubbles to obtain casting solution 7;

[0022] The mass ratio of the two-dimensional porous F-Ce nanosheets to the PVA in solution 6 is 0.02:1 to 0.1:1.

[0023] 10) The casting solution 7 is coated onto a porous support substrate with a casting solution thickness of 50-500 μm, and dried at 80-120℃ for 10 min-6 h to obtain a two-dimensional porous F-Ce nanosheet / PVA hybrid matrix membrane.

[0024] The present invention also provides a two-dimensional porous F-Ce nanosheet prepared by the above preparation method.

[0025] / PVA hybrid matrix membrane.

[0026] This invention also provides an application of a two-dimensional porous F-Ce nanosheet / PVA hybrid matrix membrane in the pervaporation and dehydration of caprolactam.

[0027] Beneficial effects

[0028] Compared with the prior art, the advantages and positive effects of the present invention are as follows:

[0029] 1. Two-dimensional F-Ce nanosheets, with their large surface area, nanometer thickness and high aspect ratio, have a strong interaction with polymer PVA, and the two have good interfacial compatibility, which solves the problem of poor compatibility between inorganic fillers and polymer matrix in traditional mixed matrix membranes.

[0030] 2. Porous F-Ce two-dimensional nanosheets have efficient water molecule transport channels and excellent stability, and enhance the membrane's anti-swelling properties, solving the problems of poor permeation flux and separation factor and poor membrane stability in traditional pervaporation mixed matrix membranes during caprolactam dehydration.

[0031] 3. This invention is the first to introduce two-dimensional porous F-Ce nanosheets into polyvinyl alcohol to prepare a mixed matrix membrane for pervaporation dehydration of caprolactam. This membrane preparation method is simple to operate, has mild preparation conditions, and is easy to scale up for production, providing a much-needed pervaporation membrane material with high permeation flux, high selectivity, and high stability for the field of caprolactam dehydration. Attached Figure Description

[0032] Figure 1 The image shows the SEM image of the two-dimensional porous F-Ce nanosheets obtained in step 4) of Example 3.

[0033] Figure 2 The AFM image of the two-dimensional porous F-Ce nanosheets obtained in step 4) of Example 3;

[0034] Figure 3 The image shown is a low-magnification TEM image of the two-dimensional porous F-Ce nanosheets obtained in step 4) of Example 3.

[0035] Figure 4 This is a high-magnification TEM image of the two-dimensional porous F-Ce nanosheets obtained in step 4) of Example 3;

[0036] Figure 5 This is a high-magnification SEM image of the surface of the two-dimensional porous F-Ce nanosheet / PVA hybrid matrix film obtained in Example 3;

[0037] Figure 6 High-magnification SEM image of the cross-section of the two-dimensional porous F-Ce nanosheet / PVA hybrid matrix membrane obtained in Example 3;

[0038] Figure 7 The pervaporation caprolactam dehydration performance of the F-Ce / PVA mixed matrix membranes obtained in Examples 1-4 and the membrane materials prepared in Comparative Examples 1-2 are shown in the diagram.

[0039] Figure 8 The swelling properties of the F-Ce / PVA hybrid matrix membranes obtained in Examples 1-4 and the membrane material prepared in Comparative Example 1 are shown in the diagrams. Detailed Implementation

[0040] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0041] Example 1

[0042] 1) Dissolve 1.1 g of cerium acetate in 260 mL of deionized water that has been treated with high-purity nitrogen for 30 min to obtain solution 1;

[0043] 2) Dissolve 0.12g of sodium fluoride in 100mL of deionized water that has been treated with high-purity nitrogen for 30min to obtain solution 2;

[0044] 3) While stirring, add solution 2 dropwise to solution 1 and react at room temperature for 3 hours to obtain a suspension;

[0045] 4) The suspension obtained in step 3) is centrifuged, washed, and freeze-dried to obtain the two-dimensional porous F-Ce nanosheets;

[0046] 5) Dissolve 5g of PVA 1799 in 100mL of deionized water at 95℃ and stir for 3h to obtain solution 3;

[0047] 6) Add 2.14 g of polyacrylic acid-2-acrylamide-2-methylpropanesulfonic acid copolymer to solution 3, stir for 30 min to obtain solution 4;

[0048] 7) Take 1 mol L -1 Sulfuric acid aqueous solution was added dropwise to solution 4 to adjust the pH to 1. Stirring was continued for 6 hours. After heating was stopped, the solution was cooled to room temperature to obtain solution 5.

[0049] 8) Add 1 mol L to solution 5 -1 Sodium hydroxide aqueous solution, adjusted to pH 9, and stirred for 30 min to obtain solution 6;

[0050] 9) Introduce 0.1g of two-dimensional porous F-Ce nanosheets obtained in step 4) into solution 6, ultrasonically disperse for 30min, and allow to stand to remove bubbles to obtain casting solution 7;

[0051] 10) The casting solution 7 was coated onto a porous polyacrylonitrile plate substrate with a casting solution thickness of 150 μm. The film was dried at 100 °C for 30 min to obtain a two-dimensional porous F-Ce nanosheet / PVA hybrid matrix film, labeled as F-Ce / PVA-2.

[0052] Example 2

[0053] 1) Dissolve 1.1 g of cerium acetate in 260 mL of deionized water that has been treated with high-purity nitrogen for 30 min to obtain solution 1;

[0054] 2) Dissolve 0.12g of sodium fluoride in 100mL of deionized water that has been treated with high-purity nitrogen for 30min to obtain solution 2;

[0055] 3) While stirring, add solution 2 dropwise to solution 1 and react at room temperature for 3 hours to obtain a suspension;

[0056] 4) The suspension obtained in step 3) is centrifuged, washed, and freeze-dried to obtain the two-dimensional porous F-Ce nanosheets;

[0057] 5) Dissolve 5g of PVA 1799 in 100mL of deionized water at 95℃ and stir for 3h to obtain solution 3;

[0058] 6) Add 2.14 g of polyacrylic acid-2-acrylamide-2-methylpropanesulfonic acid copolymer to solution 3, stir for 30 min to obtain solution 4;

[0059] 7) Take 1 mol L -1 Sulfuric acid aqueous solution was added dropwise to solution 4 to adjust the pH to 1. Stirring was continued for 6 hours. After heating was stopped, the solution was cooled to room temperature to obtain solution 5.

[0060] 8) Add 1 mol L to solution 5 -1 Sodium hydroxide aqueous solution, adjusted to pH 9, and stirred for 30 min to obtain solution 6;

[0061] 9) Introduce 0.2g of two-dimensional porous F-Ce nanosheets obtained in step 4) into solution 6, ultrasonically disperse for 30min, and allow to stand to remove bubbles to obtain casting solution 7;

[0062] 10) The casting solution 7 was coated onto a porous polyacrylonitrile plate substrate with a casting solution thickness of 150 μm. The film was dried at 100 °C for 30 min to obtain a two-dimensional porous F-Ce nanosheet / PVA hybrid matrix film, labeled as F-Ce / PVA-4.

[0063] Example 3

[0064] 1) Dissolve 1.1 g of cerium acetate in 260 mL of deionized water that has been treated with high-purity nitrogen for 30 min to obtain solution 1;

[0065] 2) Dissolve 0.12g of sodium fluoride in 100mL of deionized water that has been treated with high-purity nitrogen for 30min to obtain solution 2;

[0066] 3) While stirring, add solution 2 dropwise to solution 1 and react at room temperature for 3 hours to obtain a suspension;

[0067] 4) The suspension obtained in step 3) is centrifuged, washed, and freeze-dried to obtain the two-dimensional porous F-Ce nanosheets; the SEM image of the two-dimensional porous F-Ce nanosheets is shown below. Figure 1 As shown, the AFM diagram is as follows Figure 2 As shown, the low-magnification TEM image is as follows: Figure 3 As shown, the high-magnification TEM image is as follows: Figure 4 As shown;

[0068] 5) Dissolve 5g of PVA 1799 in 100mL of deionized water at 95℃ and stir for 3h to obtain solution 3;

[0069] 6) Add 2.14 g of polyacrylic acid-2-acrylamide-2-methylpropanesulfonic acid copolymer to solution 3, stir for 30 min to obtain solution 4;

[0070] 7) Take 1 mol L -1 Sulfuric acid aqueous solution was added dropwise to solution 4 to adjust the pH to 1. Stirring was continued for 6 hours. After heating was stopped, the solution was cooled to room temperature to obtain solution 5.

[0071] 8) Add 1 mol L to solution 5 -1 Sodium hydroxide aqueous solution, adjusted to pH 9, and stirred for 30 min to obtain solution 6;

[0072] 9) Introduce 0.3g of two-dimensional porous F-Ce nanosheets obtained in step 4) into solution 6, ultrasonically disperse for 30min, and allow to stand to remove bubbles to obtain casting solution 7;

[0073] 10) Casting solution 7 was coated onto a porous polyacrylonitrile plate substrate to a thickness of 150 μm. The mixture was dried at 100 °C for 30 min to obtain a two-dimensional porous F-Ce nanosheet / PVA hybrid matrix membrane, labeled F-Ce / PVA-6. A high-magnification SEM image of the surface of F-Ce / PVA-6 is shown below. Figure 5 As shown, the high-magnification SEM image of the cross-section of F-Ce / PVA-6 is as follows. Figure 6 As shown.

[0074] Example 4

[0075] 1) Dissolve 1.1 g of cerium acetate in 260 mL of deionized water that has been treated with high-purity nitrogen for 30 min to obtain solution 1;

[0076] 2) Dissolve 0.12g of sodium fluoride in 100mL of deionized water that has been treated with high-purity nitrogen for 30min to obtain solution 2;

[0077] 3) While stirring, add solution 2 dropwise to solution 1 and react at room temperature for 3 hours to obtain a suspension;

[0078] 4) The suspension obtained in step 3) is centrifuged, washed, and freeze-dried to obtain the two-dimensional porous F-Ce nanosheets;

[0079] 5) Dissolve 5g of PVA 1799 in 100mL of deionized water at 95℃ and stir for 3h to obtain solution 3;

[0080] 6) Add 2.14 g of polyacrylic acid-2-acrylamide-2-methylpropanesulfonic acid copolymer to solution 3, stir for 30 min to obtain solution 4;

[0081] 7) Take 1 mol L -1 Sulfuric acid aqueous solution was added dropwise to solution 4 to adjust the pH to 1. Stirring was continued for 6 hours. After heating was stopped, the solution was cooled to room temperature to obtain solution 5.

[0082] 8) Add 1 mol L to solution 5 -1 Sodium hydroxide aqueous solution, adjusted to pH 9, and stirred for 30 min to obtain solution 6;

[0083] 9) Introduce 0.4g of two-dimensional porous F-Ce nanosheets obtained in step 4) into solution 6, ultrasonically disperse for 30min, and allow to stand to remove bubbles to obtain casting solution 7;

[0084] 10) The casting solution 7 was coated onto a porous polyacrylonitrile plate substrate with a casting solution thickness of 150 μm. The film was dried at 100 °C for 30 min to obtain a two-dimensional porous F-Ce nanosheet / PVA hybrid matrix film, labeled as F-Ce / PVA-8.

[0085] Comparative Example 1

[0086] 1) Dissolve 5g of PVA 1799 in 100mL of deionized water at 95℃ and stir for 3h to obtain solution 1;

[0087] 2) Add 2.14 g of polyacrylic acid-2-acrylamide-2-methylpropanesulfonic acid copolymer to solution 1, stir for 30 min to obtain solution 2;

[0088] 3) Take 1 mol L -1 Sulfuric acid aqueous solution was added dropwise to solution 2 to adjust the pH to 1. Stirring was continued for 6 hours. After heating was stopped, the solution was cooled to room temperature to obtain solution 3.

[0089] 4) Add 1 mol L to solution 3 -1 Sodium hydroxide aqueous solution was used to adjust the pH to 9, and the mixture was stirred for 30 minutes. After standing to remove bubbles, casting solution 4 was obtained.

[0090] 5) Coat the casting solution 4 onto a polyacrylonitrile porous plate substrate with a casting solution thickness of 150 μm, and dry at 100 °C for 30 min to obtain a PVA composite membrane, labeled as PVA / PAN.

[0091] Comparative Example 2

[0092] 1) Dissolve 5g of PVA 1799 in 100mL of deionized water at 95℃ and stir for 3h to obtain solution 1;

[0093] 2) Add 2.14 g of polyacrylic acid-2-acrylamide-2-methylpropanesulfonic acid copolymer to solution 3, stir for 30 min to obtain solution 2;

[0094] 3) Take 1 mol L -1 Sulfuric acid aqueous solution was added dropwise to solution 2 to adjust the pH to 1. Stirring was continued for 6 hours. After heating was stopped, the solution was cooled to room temperature to obtain solution 3.

[0095] 4) Add 1 mol L to solution 3 -1 Sodium hydroxide aqueous solution, adjusted to pH 9, and stirred for 30 min to obtain solution 4;

[0096] 5) Introduce 0.3g of nano-silica particles (10-20nm in diameter) into solution 4, disperse them by ultrasonication for 30min, and after standing to remove bubbles, obtain casting solution 5;

[0097] 6) The casting solution 5 was coated onto a porous polyacrylonitrile plate substrate with a casting solution thickness of 150 μm. The mixture was dried at 100 °C for 30 min to obtain a nano-silica particle / PVA mixed matrix membrane, labeled as Silica / PVA-6.

[0098] The membrane materials prepared in Examples 1-4 and Comparative Examples 1-2 were tested for caprolactam dehydration performance using a pervaporation device. The results are as follows: Figure 7 As shown. The specific testing standards are as follows:

[0099] The effective area of ​​the membrane used in the test was 12 cm². 2 The feed solution is a 70 wt% caprolactam aqueous solution, and the feed solution circulation rate is 40 L / h. -1 The test system temperature was maintained at 40℃. A vacuum pump was used to maintain the permeate-side pressure below 300 Pa, and the collector was immersed in liquid nitrogen to collect the permeate-side components. The components of the feed solution and permeate were tested using a UV-6100 ultraviolet spectrophotometer (Shanghai Meipuda Instrument Co., Ltd.). Each membrane was measured at least three times, and the average value was taken. The total permeate flux (J, gm³) was calculated according to the following equation. -2 h -1 ) and separation factor (β):

[0100]

[0101] Where W(g) is the total mass of the permeate, and A(m) is the total mass of the permeate. 2 ) represents the effective area of ​​the membrane, and t(h) represents the test time. i and y i These represent the mass concentration (wt%) of caprolactam in the feed solution and the permeate, respectively.

[0102] To test the swelling degree of membrane materials, the membrane sample must first be dried in a 60℃ oven for 24 hours, and then fully immersed in water for 72 hours. The swollen membrane sample is then wiped dry with filter paper, and its mass is recorded. By measuring the mass of the dry membrane and the swollen membrane, the swelling degree (DS) of the fabricated membrane in water can be determined. The calculation method is as follows:

[0103]

[0104] Where Wd(g) is the dry film mass and Ww(g) is the mass of the film after swelling.

[0105] Depend on Figure 7 It can be seen that in Examples 1-4, high-performance hybrid matrix membranes were prepared by introducing two-dimensional porous F-Ce nanosheets into the PVA matrix, with permeation flux and separation factor significantly higher than those of the membrane materials prepared in Comparative Examples 1-2. The hybrid matrix membrane prepared in Example 3 achieved a permeation flux and separation factor of 1363 g m³. -2 h -1 The concentration of 1554 g / m² was significantly higher than that of the PVA / PAN film prepared in Comparative Example 1 (700 g / m²). -2 h -1 The concentration was 750, significantly higher than the 820 g / m² of the conventional inorganic silica-filled Silica / PVA-6 film prepared in Comparative Example 2. -2 h -1 and 906. Depend on Figure 8 It can be seen that as the amount of two-dimensional porous F-Ce nanosheets increases, the swelling degree of the prepared F-Ce nanosheet / PVA hybrid matrix membrane in water gradually decreases, and is lower than that of the PVA membrane in water. These results indicate that the two-dimensional porous F-Ce nanosheet-filled PVA hybrid matrix membrane used in this invention exhibits excellent separation performance in caprolactam dehydration applications, with significantly improved permeation flux, separation factor, and anti-swelling properties. Furthermore, the process is simple and easy to scale up.

[0106] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. The application of a two-dimensional porous F-Ce nanosheet / PVA hybrid matrix membrane in the pervaporation and dehydration of caprolactam, characterized in that: Two-dimensional porous F-Ce nanosheets were introduced into a polyvinyl alcohol (PVA) solution to obtain a casting solution, wherein the mass ratio of two-dimensional porous F-Ce nanosheets to PVA was 0.02:1 to 0.1:1; then the casting solution was coated onto a porous support substrate to prepare a thin and defect-free two-dimensional porous F-Ce nanosheet / PVA hybrid matrix film.

2. The application according to claim 1, characterized in that: The polyvinyl alcohol (PVA) is selected from one or more of PVA 105, PVA 117, PVA 124, PVA 1788, PVA 1792, PVA 1799, and PVA 2488.

3. The application according to claim 1, characterized in that: The porous support substrate is an organic porous material or an inorganic porous material, and its shape is flat, tubular or hollow fiber.

4. The application according to claim 1, characterized in that: The porous support substrate is made of any one of the following materials: polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyacrylonitrile, polysulfone, polyethersulfone, and ceramic.

5. The application according to claim 1, characterized in that: The specific preparation steps of the two-dimensional porous F-Ce nanosheet / PVA hybrid matrix film include: 1) Dissolve cerium acetate in deionized water treated with high-purity nitrogen to obtain solution 1, with a concentration of 1-5 g·L⁻¹. -1 ; 2) Dissolve sodium fluoride in deionized water treated with high-purity nitrogen to obtain solution 2, with a concentration of 0.5–3 g·L⁻¹. -1 ; 3) Add solution 2 dropwise to solution 1 and stir at room temperature for 1 to 12 hours to obtain a suspension; wherein the volume ratio of solution 1 to solution 2 is 2:1 to 5:

1. 4) The suspension obtained in step 3) is centrifuged, washed, and freeze-dried to obtain the two-dimensional porous F-Ce nanosheets; 5) Dissolve PVA in deionized water at 80–95℃ to obtain solution 3 with a concentration of 20–50 g·L⁻¹. -1 ; 6) Add cross-linking agent to solution 3 and stir for 10-60 min to obtain solution 4; The mass ratio of crosslinking agent to PVA is 0.05:1 to 0.5:1; the crosslinking agent is one or more of boric acid, glutaraldehyde, maleic acid, maleic acid, dimethylol urea, trimethylol melamine, sulfonated succinic acid, 4-sulfophthalic acid, and polyacrylic acid-2-acrylamide-2-methylpropane sulfonic acid copolymer. 7) Take 0.1–2 mol·L⁻¹ -1 The catalyst was added dropwise to solution 4, the pH was adjusted to 1-5, stirring was continued for 3-6 hours, and after heating was stopped, the solution was cooled to room temperature to obtain solution 5. The catalyst is either sulfuric acid or hydrochloric acid. 8) Add 0.1–1 mol·L⁻¹ to solution 5. -1 An alkaline aqueous solution is prepared, and the pH is adjusted to 7–12. The solution is stirred for 10 min–6 h to obtain solution 6. The alkaline substance is one or more of sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium amide, ammonia, ethanolamine, diethanolamine, and triethylamine. 9) The two-dimensional porous F-Ce nanosheets obtained in step 4) are introduced into the solution 6, ultrasonically dispersed, and allowed to stand to remove bubbles to obtain casting solution 7; 10) Coat the casting solution 7 onto the porous support substrate with a casting solution thickness of 50-500 μm, and dry at 80-120℃ for 10 min-6 h to obtain a two-dimensional porous F-Ce nanosheet / PVA hybrid matrix membrane.

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