A method for preparing a maf / zif crystal film for organic enrichment

Abstract

The application discloses a preparation method of MAF / ZIF crystal film for organic matter enrichment. The preparation method comprises the following steps: placing a porous gamma-Al2O3 carrier in an acetic acid aqueous solution, carrying out a solvothermal reaction to obtain a gamma-AlOOH precursor layer, and then sequentially immersing the carrier modified with the precursor layer in solutions of imidazole ligands and metal salts to obtain the MAF / ZIF crystal film through liquid phase epitaxy self-assembly. The carrier is modified by using a hydrothermal method, a layer of gamma-AlOOH precursor is pre-grown on the surface of the porous gamma-Al2O3 carrier, and then the MAF / ZIF crystal film is obtained through a layer-by-layer immersion method. The prepared MAF / ZIF film material has excellent stability and separation performance for an organic matter / water system, and is an ideal organic matter enrichment material.

Description

Technical Field

[0001] This invention relates to a method for preparing a MAF / ZIF crystal membrane for separating organic matter / water systems, belonging to the field of membrane separation materials. Background Technology

[0002] Pervaporation (PV) is currently a hot research topic in the field of organic matter separation. PV offers advantages such as ease of operation, low energy consumption, and no secondary pollution. Furthermore, it overcomes the limitations of traditional distillation methods in separating near-boiling and azeotropic organic mixtures, demonstrating significant advantages in energy conservation, emission reduction, cost savings, and improved separation stability.

[0003] Enrichment and purification of low-concentration organic chemicals through pervaporation is a key technology in the chemical industry. Membrane materials are the core components, and their structure and performance determine the separation efficiency of the entire pervaporation process. Compared with traditional separation materials, metal-organic frameworks (MOFs) offer numerous advantages, including large specific surface area, diverse topologies, and tunable pore structures, making them promising candidates for liquid separation (V. Cristina, EJ Mater Chem.A. 2020). Zeolite imidazole frameworks (ZIFs) are an important subclass of MOFs, composed of transition metals (Zn / Co) coordinated with imidazole ligands. They possess ultraporous structures and high thermal and chemical stability, making them ideal membrane separation materials. However, reports on the preparation of pure ZIF membranes are limited. The high nucleation rate of metal polyazole frameworks (MAFs) / zeolite imidazole frameworks (ZIFs) results in a high and uniform nucleation rate in the synthesis solution, which is unfavorable for forming a continuous and complete pure ZIF membrane layer on porous substrates, significantly limiting the large-scale application of MOF membranes. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing a MAF / ZIF crystal film with stable structure and excellent enrichment performance of organic matter (including alcohols and ketones).

[0005] A method for preparing MAF / ZIF crystalline membranes for enriching low-concentration organic matter involves a hydrothermal modification of a support. A porous γ-Al₂O₃ support is used as an inorganic aluminum source and reacts hydrothermally with an acetic acid solution to obtain a γ-AlOOH precursor membrane (layer). The precursor-modified support is then sequentially immersed in solutions of imidazole ligands and metal salts, followed by liquid-phase epitaxial self-assembly to obtain the MAF / ZIF crystalline membrane.

[0006] (1) Preparation of γ-AlOOH precursor layer (film)

[0007] A porous γ-Al₂O₃ support was placed in an aqueous acetic acid solution and subjected to a solvothermal reaction under sealed conditions to pre-seed a nanosheet-like γ-AlOOH precursor layer on the support surface, resulting in a γ-AlOOH precursor film, i.e., a precursor-modified support. The reaction temperature was 130–220 °C, and the reaction time was 2–48 h.

[0008] After the reaction was completed, the membrane was cooled to room temperature and then washed and dried. Specifically, after the reaction was completed, the membrane was allowed to cool naturally to room temperature. The membrane was then placed in a beaker filled with water and sonicated at 50-400 W for 5-30 seconds. After that, it was washed with deionized water or anhydrous ethanol for 5-120 minutes. The washed product was then dried overnight in an oven at 50-80°C.

[0009] Preferably, the porous Al2O3 support is placed horizontally in the mother liquor (reaction solution) and reacted at 180-200°C for 4-12 hours.

[0010] Preferably, the pH of the acetic acid aqueous solution is 2 to 4.

[0011] Preferably, the ultrasonic treatment time of the γ-AlOOH precursor membrane is 10-30 seconds.

[0012] Preferably, the porous γ-Al2O3 support has a diameter of 18 mm and a pore size of 5 nm.

[0013] (2) Preparation of MAF / ZIF crystal film

[0014] Hydrated nitrate and imidazole ligands were dissolved separately in methanol, and the molar ratio of hydrated nitrate to solvent was adjusted to 1:400–6000. ， The molar ratio of imidazole ligands to solvent is 1:400–6000. The solution is thoroughly stirred at room temperature (generally 25°C) to completely dissolve the imidazole ligands, resulting in metal salt solutions and imidazole ligand solutions. The γ-AlOOH precursor membrane is then sequentially immersed in the imidazole ligand solutions and metal salt solutions, and reacted at 0–40°C for 5–300 min. Through a layer-by-layer impregnation method, MAF / ZIF crystal membranes are obtained.

[0015] After the reaction is complete, the membrane is washed and dried. Specifically, the membrane is placed in a beaker containing deionized water and sonicated at 50-400W for 5-30 seconds. After washing with N,N-dimethylformamide or anhydrous ethanol for 5-120 minutes, it is placed in an oven to dry at 50-100℃ overnight.

[0016] Preferably, the molar ratio of the hydrated nitrate to the solvent is 1:600 ​​to 2000. ，The molar ratio of imidazole ligands to solvents is 1:600 ​​to 2000.

[0017] Preferably, the γ-AlOOH precursor membrane is sequentially immersed in an imidazole ligand solution and a metal salt solution, and reacted at 10–30°C for 6–72 h.

[0018] Preferably, the γ-AlOOH precursor membrane is immersed in the imidazole ligand solution and the metal salt solution for the same amount of time each time.

[0019] Preferably, the immersion operation can be repeated multiple times; the number of immersions is 2 to 6, and the immersion time for each immersion is 20 to 60 minutes.

[0020] Preferably, the membrane immersion and washing step includes immersion and washing in N,N-dimethylformamide or anhydrous ethanol at room temperature for 30 to 60 minutes.

[0021] Preferably, the concentration of organic matter in the low-concentration organic matter is 0.1 wt.% to 5 wt.%.

[0022] Another object of the present invention is to provide a MAF / ZIF crystal film prepared by the above method.

[0023] Another object of the present invention is to provide the application of the above-described MAF / ZIF crystal membrane in the enrichment of organic matter (i.e., separation of organic matter / water systems), wherein the organic matter includes at least one of methanol, ethanol, n-propanol, isopropanol, n-butanol, and acetone. The concentration of organic matter in the organic matter / water system is 0.1 wt.% to 5 wt.%.

[0024] Compared with the prior art, the advantages of the present invention are:

[0025] (1) The preparation process is rapid and simple, and it is a green chemical synthesis method;

[0026] (2) The experimental strategy is ingenious. By using the γ-AlOOH modified support method, a layer of γ-AlOOH precursor was pre-seeded on the surface of the porous γ-Al2O3 support as an inorganic Al source to prepare the γ-AlOOH precursor layer. Then, using γ-AlOOH as the precursor template, a high-performance and stable MAF / ZIF crystal membrane was prepared by layer-by-layer impregnation method. It has excellent separation performance for organic matter / water system separation and is an ideal material for organic matter enrichment and purification. Attached Figure Description

[0027] This invention appendix Figure 8 Size:

[0028] Figure 1These are X-ray diffraction patterns of γ-AlOOH precursor films at different reaction temperatures in Examples 1-4.

[0029] Figure 2 These are scanning electron microscope (SEM) images of the γ-AlOOH precursor films obtained at different reaction temperatures in Examples 1-4.

[0030] Figure 3 These are scanning electron microscope (SEM) images of MAF-6 films obtained from different immersion times in Examples 5-8.

[0031] Figure 4 This is a graph showing the separation selectivity and permeability of the MAF-6 crystal membrane in the butanol / water system as a function of the number of immersions in Example 7.

[0032] Figure 5 This describes the separation performance of the MAF-6 crystal membrane in Example 7 for different concentrations of n-butanol / water systems.

[0033] Figure 6 This refers to the separation performance of the MAF-6 crystal membrane in Example 7 for other organic / water systems.

[0034] Figure 7 The results are from the stability test of the MAF-6 crystal membrane for the separation of n-butanol / water system in Example 7.

[0035] Figure 8 This refers to the separation performance of the ZIF crystal membrane in Examples 9-11 for the n-butanol / water system. Detailed Implementation

[0036] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0037] Example 1. Preparation of γ-AlOOH-1 precursor membrane

[0038] Measure 20 ml of acetic acid aqueous solution (pH=3) and transfer it to a 25 ml polytetrafluoroethylene-lined reactor. Place a circular porous γ-Al2O3 support with a diameter of 18 mm and a pore size of 5 nm horizontally in the above aqueous solution. Then, seal the reactor in a stainless steel autoclave and place it in an oven to heat to 135 °C, maintaining the temperature for 4 hours for reaction.

[0039] After the reaction was completed, the mixture was allowed to cool naturally to room temperature. The inner liner of the reactor was opened and the supernatant was poured off. The γ-AlOOH precursor membrane was first placed in water and ultrasonically treated at 300W for 20s. Then it was immersed and washed with deionized water for 60min. After that, it was placed in a 60℃ oven to dry overnight to obtain the γ-AlOOH-1 precursor membrane.

[0040] Example 2. Preparation of γ-AlOOH-2 precursor membrane

[0041] Measure 20 ml of acetic acid aqueous solution (pH=3) and transfer it to a 25 ml polytetrafluoroethylene-lined reactor. Place a circular porous γ-Al2O3 support with a diameter of 18 mm and a pore size of 5 nm horizontally in the above aqueous solution. Then, seal the reactor in a stainless steel autoclave and place it in an oven to heat to 150 °C, maintaining the temperature for 4 hours for reaction.

[0042] After the reaction was completed, the mixture was allowed to cool naturally to room temperature. The inner liner of the reactor was opened and the supernatant was poured off. The γ-AlOOH precursor membrane was first placed in water and ultrasonically treated at 300W for 20s. Then it was immersed and washed with deionized water for 60min. After that, it was placed in a 60℃ oven to dry overnight to obtain the γ-AlOOH-2 precursor membrane.

[0043] Example 3. Preparation of γ-AlOOH-3 precursor membrane

[0044] Measure 20 ml of acetic acid aqueous solution (pH=3) and transfer it to a 25 ml polytetrafluoroethylene-lined reactor. Place a circular porous γ-Al2O3 support with a diameter of 18 mm and a pore size of 5 nm horizontally in the above aqueous solution. Then, seal the reactor in a stainless steel autoclave and place it in an oven to heat to 180 °C, maintaining the temperature for 4 hours.

[0045] After the reaction was completed, the mixture was allowed to cool naturally to room temperature. The inner liner of the reactor was opened and the supernatant was poured off. The γ-AlOOH precursor membrane was first placed in water and ultrasonically treated at 300W for 20s. Then it was immersed and washed with deionized water for 60min and dried in a 60℃ oven overnight to obtain the γ-AlOOH-3 precursor membrane.

[0046] Example 4. Preparation of γ-AlOOH-4 precursor membrane

[0047] Measure 20 ml of acetic acid aqueous solution (pH=3) and transfer it to a 25 ml polytetrafluoroethylene-lined reactor. Place a circular porous γ-Al2O3 support with a diameter of 18 mm and a pore size of 5 nm horizontally in the above aqueous solution. Then, seal the reactor in a stainless steel autoclave and place it in an oven to heat to 220 °C, maintaining the temperature for 4 hours for reaction.

[0048] After the reaction was completed, the mixture was allowed to cool naturally to room temperature. The inner liner of the reactor was opened and the supernatant was poured off. The γ-AlOOH precursor membrane was first placed in water and ultrasonically treated at 300W for 20s. Then it was immersed and washed with deionized water for 60min. After that, it was placed in a 60℃ oven to dry overnight to obtain the γ-AlOOH-4 precursor membrane.

[0049] Example 5. Preparation of MAF-6-1 crystal film

[0050] The γ-AlOOH precursor membrane (i.e., the γ-AlOOH-3 precursor membrane) was prepared using the method described in Example 3.

[0051] 0.297 g of zinc nitrate hexahydrate and 0.190 g of 2-ethylimidazole were weighed and dissolved in 25 ml of methanol, respectively. The solutions were stirred thoroughly at room temperature until completely dissolved, yielding metal salt solution and ligand solution, respectively. The γ-AlOOH precursor membrane was sequentially immersed in the ligand-metal solution (immersion was performed twice, first in the ligand solution and then in the metal salt solution), with each immersion being carried out at room temperature for 30 min.

[0052] After the reaction was completed, the membrane was transferred to a beaker containing deionized water, ultrasonically treated for 15 seconds using a 200W ultrasonic cleaner, washed with DMF for 30 minutes, and then dried overnight in a 60℃ oven to obtain the MAF-6-1 crystal membrane.

[0053] Example 6. Preparation of MAF-6-2 crystal film

[0054] The γ-AlOOH precursor membrane (i.e., the γ-AlOOH-3 precursor membrane) was prepared using the method described in Example 3.

[0055] 0.297 g of zinc nitrate hexahydrate and 0.190 g of 2-ethylimidazole were weighed and dissolved in 25 ml of methanol, respectively. The solutions were stirred thoroughly at room temperature to obtain metal salt solutions and ligand solutions, respectively. The γ-AlOOH precursor membrane was sequentially immersed in the ligand-metal-ligand solution (immersion was performed 3 times: first in the ligand solution, then in the metal salt solution, and finally in the ligand solution). Each immersion was carried out at room temperature for 30 min.

[0056] After the reaction was completed, the membrane was transferred to a beaker containing deionized water, ultrasonically treated for 15 seconds using a 200W ultrasonic cleaner, washed with DMF for 30 minutes, and then dried overnight in a 60℃ oven to obtain the MAF-6-2 crystal membrane.

[0057] Example 7. Preparation of MAF-6-3 crystal film

[0058] The γ-AlOOH precursor membrane (i.e., the γ-AlOOH-3 precursor membrane) was prepared using the method described in Example 3. 0.297 g of zinc nitrate hexahydrate and 0.190 g of 2-ethylimidazole were weighed and dissolved in 25 ml of methanol, respectively. The solutions were stirred thoroughly at room temperature until completely dissolved, yielding metal salt solutions and ligand solutions, respectively. The γ-AlOOH precursor membrane was sequentially immersed in a ligand-metal-ligand-metal solution (immersion was performed four times: first in the ligand solution, then in the metal salt solution, then in the ligand solution again, and finally in the metal salt solution again). Each immersion was carried out at room temperature for 30 min.

[0059] After the reaction was completed, the membrane was transferred to a beaker containing deionized water, ultrasonically treated for 15 seconds using a 200W ultrasonic cleaner, washed with DMF for 30 minutes, and then dried overnight in a 60℃ oven to obtain the MAF-6-3 crystal membrane.

[0060] Example 8. Preparation of MAF-6-4 crystal film

[0061] The γ-AlOOH precursor membrane (i.e., the γ-AlOOH-3 precursor membrane) was prepared using the method described in Example 3. 0.297 g of zinc nitrate hexahydrate and 0.190 g of 2-ethylimidazole were weighed and dissolved in 25 ml of methanol, respectively. The solutions were stirred thoroughly at room temperature until completely dissolved, yielding metal salt solutions and ligand solutions, respectively. The γ-AlOOH precursor membrane was sequentially immersed in a ligand-metal-ligand-metal-ligand solution (immersion was performed 5 times: first in the ligand solution, then in the metal salt solution, then in the ligand solution again, then in the metal salt solution again, and finally in the ligand solution). Each immersion was carried out at room temperature for 30 min.

[0062] After the reaction was completed, the membrane was transferred to a beaker containing deionized water, ultrasonically treated for 15 seconds using a 200W ultrasonic cleaner, washed with DMF for 30 minutes, and then dried overnight in a 60℃ oven to obtain the MAF-6-4 crystal membrane.

[0063] Example 9. Preparation of ZIF-8 crystal film

[0064] The γ-AlOOH precursor membrane (i.e., the γ-AlOOH-3 precursor membrane) was prepared using the method described in Example 3. 0.149 g of zinc nitrate hexahydrate and 2.87 g of 2-methylimidazole were weighed and dissolved in 25 ml of methanol, respectively. The solutions were stirred thoroughly at room temperature until completely dissolved, yielding metal salt solutions and ligand solutions, respectively. The γ-AlOOH precursor membrane was sequentially immersed in a ligand-metal-ligand-metal solution (immersion was performed four times: first in the ligand solution, then in the metal salt solution, then in the ligand solution again, and finally in the metal salt solution again). Each immersion was carried out at room temperature for 30 min.

[0065] After the reaction was completed, the membrane was transferred to a beaker containing deionized water, ultrasonically treated for 15 seconds using a 200W ultrasonic cleaner, washed with DMF for 30 minutes, and then dried overnight in a 60℃ oven to obtain the ZIF-8 crystal membrane.

[0066] Example 10. Preparation of ZIF-67 crystal film

[0067] The γ-AlOOH precursor membrane (i.e., the γ-AlOOH-3 precursor membrane) was prepared using the method described in Example 3.

[0068] 0.146 g of cobalt nitrate hexahydrate and 2.87 g of 2-methylimidazole were weighed and dissolved in 25 ml of methanol, respectively. The solutions were stirred thoroughly at room temperature until completely dissolved, yielding metal salt solutions and ligand solutions, respectively. The γ-AlOOH precursor membrane was sequentially immersed in the ligand-metal-ligand-metal solution (immersion was performed 4 times: first in the ligand solution, then in the metal salt solution, then in the ligand solution again, and finally in the metal salt solution). Each immersion was carried out at room temperature for 30 min.

[0069] After the reaction was completed, the membrane was transferred to a beaker containing deionized water, ultrasonically treated for 15 seconds using a 200W ultrasonic cleaner, washed with DMF for 30 minutes, and then dried overnight in a 60℃ oven to obtain the ZIF-67 crystal membrane.

[0070] Example 11. Preparation of ZIF-71 crystal film

[0071] The γ-AlOOH precursor membrane (i.e., the γ-AlOOH-3 precursor membrane) was prepared using the method described in Example 3.

[0072] 0.149 g of zinc nitrate hexahydrate and 0.274 g of dichloroimidazole were weighed and dissolved in 25 ml of methanol, respectively. The solutions were stirred thoroughly at room temperature until completely dissolved, yielding metal salt solutions and ligand solutions, respectively. The γ-AlOOH precursor membrane was sequentially immersed in the ligand-metal-ligand-metal solution (immersion was performed 4 times: first in the ligand solution, then in the metal salt solution, then in the ligand solution again, and finally in the metal salt solution). Each immersion was carried out at room temperature for 30 min.

[0073] After the reaction was completed, the membrane was transferred to a beaker containing deionized water, ultrasonically treated for 15 seconds using a 200W ultrasonic cleaner, washed with DMF for 30 minutes, and then dried overnight in a 60℃ oven to obtain the ZIF-71 crystal membrane.

[0074] The structure of the MIL-160 crystal membrane was characterized using X-ray diffraction (XRD) and scanning electron microscopy (SEM), and its separation performance for organic / water systems was tested using a pervaporation apparatus. The morphology, structure, and organic / water separation performance of the crystal membrane prepared in this invention are as follows:

[0075] Figure 1 X-ray diffraction patterns of γ-AlOOH precursor films at different reaction temperatures in Examples 1-4 are given. The characteristic peak of the γ-AlOOH layer can be observed at 14.4°, and the intensity of the characteristic peak is stronger at higher reaction temperatures, indicating that the γ-Al2O3 surface is transformed into the γ-AlOOH precursor layer.

[0076] Figure 2 The images are scanning electron microscope (SEM) images of γ-AlOOH precursor films obtained at different reaction temperatures in Examples 1-4, showing that after reaction at 135-220℃, nanosheet-like γ-AlOOH precursor layers are formed on the surface of the support.

[0077] Figure 3 The images shown are scanning electron microscope (SEM) images of MAF-6 films obtained by different immersion times in Examples 5-8, indicating that as the number of immersion times increases to 5, the MAF-6 film obtained on the carrier surface becomes uniform and dense.

[0078] Figure 4 The graphs show the changes in separation selectivity and permeability of the MAF-6 crystal membrane in Examples 5-8 with the number of impregnations for a 1 wt.% n-butanol aqueous solution. As the number of impregnations increases, the membrane selectivity gradually increases, indicating that the membrane has excellent n-butanol / water separation performance.

[0079] Figure 5 The separation performance of the MAF-6 crystal membrane in Example 7 for the 0.1wt.%-5wt.% n-butanol / water system shows that the MAF-6 membrane can achieve efficient enrichment of n-butanol / water solutions with different compositions.

[0080] Figure 6 The separation performance of the MAF-6 crystal membrane in Example 7 for a 1 wt.% organic matter (ethanol, n-propanol, isopropanol, n-butanol) / water system demonstrates that the MAF-6 crystal membrane can achieve efficient separation of various alcohol / water systems.

[0081] Figure 7 The results show the separation stability test of the MAF-6 crystal membrane in Example 7 for a 1 wt.% n-butanol / water system. During a 120-h pervaporation test, the total permeate flow and separation factor of the crystal membrane remained stable, indicating that the crystal membrane possesses excellent stability.

[0082] Figure 8 The diagrams show the separation selectivity and permeability of the ZIF crystal membranes in Examples 9-11 with 1 wt.% n-butanol aqueous solution, indicating that the prepared ZIF membranes all have excellent butanol / water enrichment performance.

Claims

1. A method for preparing a MAF / ZIF crystalline film, characterized in that, Includes the following steps: (1) Preparation of γ-AlOOH precursor membrane A porous γ-Al2O3 support was placed in an aqueous solution of deacetic acid and subjected to a solvothermal reaction under closed conditions to obtain a nanosheet-like γ-AlOOH precursor film. The reaction temperature is 130–220°C, and the reaction time is 2–48 h. (2) Preparation of MAF / ZIF crystal film Hydrated nitrate and imidazole ligands were dissolved in methanol to obtain metal salt solutions and imidazole ligand solutions, respectively. The γ-AlOOH precursor membrane was sequentially immersed in the imidazole ligand solution and the metal salt solution, and reacted at 0–40 °C for 5–300 min. The MAF / ZIF crystal membrane was obtained by layer-by-layer impregnation. The molar ratio of hydrated nitrate to solvent is 1:400–6000. ， The molar ratio of imidazole ligands to solvents is 1:400–6000; The hydrated nitrate is one or two of zinc nitrate hexahydrate, copper nitrate trihydrate, and cobalt nitrate hexahydrate; the imidazole ligand is one or more of 2-methylimidazole, 2,5-dichloroimidazole, benzimidazole, and 2-ethylimidazole.

2. The method for preparing MOF crystal films according to claim 1, characterized in that, In step (1), the pH of the acetic acid aqueous solution is 2 to 4.

3. The method for preparing MOF crystal films according to claim 1, characterized in that, In step (2), the γ-AlOOH precursor membrane is immersed in the imidazole ligand solution and the metal salt solution for the same amount of time each time.

4. The method for preparing MOF crystal films according to claim 1, characterized in that, In step (2), the number of times the layers are impregnated is 2 to 6, and the time for each impregnation is 20 to 60 minutes.

5. The method for preparing the MAF / ZIF crystal film according to claim 1, characterized in that, In step (1), after the reaction is complete, the γ-AlOOH precursor membrane is washed and dried; The washing process involves first placing the γ-AlOOH precursor membrane in water, then ultrasonically treating it at 50-400W for 5-30 seconds, followed by immersion in deionized water or anhydrous ethanol for 5-120 minutes. The drying temperature is 50-80℃, and the membrane is dried overnight.

6. The method for preparing the MAF / ZIF crystal film according to claim 1, characterized in that, In step (2), the γ-AlOOH precursor membrane is placed vertically in a solution of imidazole ligands and a solution of metal salt.

7. The method for preparing the MAF / ZIF crystal film according to claim 1, characterized in that, In step (2), after the reaction is completed, the crystal membrane is washed and dried. The washing process is as follows: first, the crystal membrane is placed in water and ultrasonically treated with 50-400w for 5-30s, and then immersed and washed with N,N-dimethylformamide or anhydrous ethanol for 5-120min. The drying temperature is 50-100℃, and the membrane is dried overnight.

8. The MAF / ZIF crystal film prepared by the method according to any one of claims 1-7.

9. The application of the MOF crystal membrane according to claim 8 in the separation of organic matter / water systems.

10. The application according to claim 9, characterized in that, The organic compound is methanol, ethanol, n-propanol, isopropanol, n-butanol, or acetone.

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