Preparation and application of MOF (Metal Organic Framework) gel assembled covalent organic framework nanosheet composite membrane

Abstract

According to the invention, metal organic framework (MOF) gel and covalent organic framework (COF) nanosheets are combined, so that a novel high-performance composite membrane is successfully developed. The three-dimensional network structure, high mechanical strength and excellent chemical stability of the MOF gel and the ultrathin characteristic, high specific surface area and adjustable and controllable functional groups of the COF nanosheets are ingeniously fused, and breakthrough progress is achieved in the aspects of material design and function integration. The composite membrane shows excellent separation performance in the antibiotic desalination process, can efficiently intercept antibiotic molecules and accurately remove salt ions, and meanwhile, keeps high water flux. In addition, the membrane material also has excellent anti-pollution capacity, can prolong the service life and reduce the operation cost, and shows wide application prospects in the fields of antibiotic wastewater treatment, industrial wastewater reuse and the like.

Description

Technical Field

[0001] The present invention relates to the preparation and application of a composite membrane of MOF gel assembled with covalent organic framework nanosheets, belonging to the field of antibiotic desalination. Background Art

[0002] Antibiotics are widely used in the fields of medicine, agriculture and animal husbandry. However, a large amount of antibiotic-containing wastewater generated during their production and use has become a major challenge in global water environment treatment. Such wastewater not only contains high concentrations of antibiotic molecules but also is mixed with a large number of salt ions. Traditional separation technologies, such as biodegradation and physical adsorption, have certain limitations in efficiently removing antibiotics or salt ions. Although reverse osmosis and nanofiltration membranes can achieve partial separation, it is difficult to meet the actual needs due to membrane fouling, high energy consumption and limited separation efficiency. Therefore, the development of new membrane materials with high water flux, excellent separation performance and anti-fouling ability has become an important hot spot and difficulty in the current research of membrane separation technology.

[0003] Metal-organic frameworks (MOFs) and covalent organic frameworks (COFs), as two types of emerging porous materials, have tunable pore sizes, high specific surface areas and excellent chemical stabilities, showing great potential in the fields of separation and desalination. The advantage of MOFs lies in the diversity of their metal nodes and organic ligands, enabling rich functionalization options and excellent mechanical strength; while COFs, due to their pure organic structures and two-dimensional or three-dimensional skeletons connected by strong covalent bonds, exhibit higher thermal stabilities and low-density material characteristics. However, in the application of antibiotic desalination, these two types of materials still face many challenges: First, antibiotic molecules usually have complex structures and large sizes, making selective separation more difficult; second, the high concentration of salt ions and the complex solution environment may have an adverse impact on the chemical stability and separation efficiency of the materials; finally, how to achieve excellent selective separation while ensuring high water flux still requires further optimization of material design.

[0004] In view of the limitations of the current technology, the present invention proposes a composite membrane of MOF gel assembled with covalent organic framework (COF) nanosheets for antibiotic desalination. The MOF gel has flexibility and dynamic regulation ability, providing efficient ion transport channels and selective separation of antibiotic molecules through its three-dimensional network structure, while overcoming the brittleness problem of traditional MOF materials. The COF nanosheets, with their regular two-dimensional structures and highly tunable pore sizes, further enhance the molecular sieving ability and improve the compatibility and stability with the MOF gel interface through functionalization modification. The synergistic effect of the MOF gel and the COF nanosheets not only enhances the mechanical strength of the composite membrane through the flexible matrix but also achieves efficient separation by precisely regulating the pore size, forming a stable interface to improve the water flux and anti-fouling ability, thus providing an efficient solution for antibiotic desalination.

[0005] The present invention is achieved through the following technical solutions: A MOF gel-assembled covalent organic framework nanosheet composite membrane is used for antibiotic desalination. This membrane material is composed of MOF gel and COF nanosheets, and stacking is achieved by vacuum-assisted self-assembly. The entire preparation process is simple and easy to control.

[0006] The MOF gel-assembled covalent organic framework nanosheet composite membrane described in the present invention specifically includes various MOF gels, such as ZIF-8 gel, ZIF-67 gel, ZIF-7 gel, UiO-66 gel, etc. These gels are all prepared by solution self-assembly; at the same time, COF nanosheets include TpPa-SO3H, TpBd-SO3H, NABAPa-SO3H, etc. Among them, ZIF-8 gel and TpPa-SO3H nanosheets are preferred.

[0007] Step 1) Preparation of MOF gel: Dissolve zinc nitrate hexahydrate in a methanol solution according to a certain mass, add a certain amount of triethylamine, dissolve dimethylimidazole in a methanol solution according to a certain mass, and finally mix and stir the two solutions for 1 hour, then centrifuge and collect to obtain ZIF-8 gel. Preparation of COF nanosheets: Dissolve 2,4,6-trihydroxy-1,3,5-benzenetricarboxaldehyde in a dimethyl sulfoxide solution according to a certain ratio and ultrasonically disperse it, denoted as the aldehyde monomer solution; dissolve 2,5-benzenedisulfonic acid in dimethyl sulfoxide according to a certain ratio and ultrasonically disperse it, denoted as the amine monomer solution. Subsequently, mix the two solutions and react for 24 hours to obtain a dark brown solution, and dialyze it with a 30000Da dialysis bag for 2 days to obtain a uniformly dispersed orange-yellow solution, that is, the TpPa-SO3H nanosheet dispersion.

[0008] Step 2) Dilution of a MOF gel-assembled covalent organic framework nanosheet: Dilute the dispersion obtained in Step 1) to deionized water to obtain a dispersion of MOF gel and COF nanosheets with a concentration of 0.05 mg mL -1 -1.

[0009] Step 3) Preparation of a MOF gel-assembled covalent organic framework nanosheet composite membrane: Filter the dispersion obtained in Step 2) onto the surface of a polyacrylonitrile porous polymer membrane by vacuum-assisted self-assembly, and then dry it at 30 °C for 24 hours to obtain a MOF gel-assembled covalent organic framework nanosheet composite membrane.

[0010] Using the above-mentioned MOF gel-assembled covalent organic framework nanosheet composite membrane for antibiotic desalination separation, under the conditions of an operating temperature of 30 °C and a pressure of 2 bar, the water flux is 123 - 77.8 L m -2 -1 h-1 bar -1 -1, and the antibiotic desalination separation factor is 1.8 - 24.7.

[0011] Compared with the prior art, the advantages of the present invention are as follows:

[0012] The present invention provides a covalent organic framework nanosheet composite membrane based on MOF gel assembly for antibiotic desalination. With its flexibility and dynamic regulation ability, MOF gel provides efficient ion transport channels through a three-dimensional network structure, and shows excellent performance in the separation selectivity of antibiotic molecules, while overcoming the brittleness of traditional MOF materials. COF nanosheets, with their regular two-dimensional structure and adjustable pore size, further enhance the molecular sieving ability. The synergistic effect of MOF gel and COF nanosheets not only improves the mechanical strength of the composite membrane through a flexible matrix, but also achieves efficient separation by precisely controlling the pore size, and the stable interface helps to improve the water flux and anti-pollution ability, providing an efficient solution for antibiotic desalination.

[0013] The membrane preparation process of the present invention is simple and controllable, the membrane structure is stable, and it has good applicability, and can be extended to other similar structural materials. When the composite membrane prepared by the present invention is applied to the antibiotic desalination separation system, it shows excellent high permeability and high separation factor. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is the transmission electron microscope image of the MOF gel and COF nanosheets prepared in Example 1 of the present invention;

[0015] Figure 2 is the surface electron microscope image of Membrane 1 prepared in Example 1 of the present invention;

[0016] Figure 3 is the cross-sectional electron microscope image of Membrane 1 prepared in Example 1 of the present invention;

[0017] Figure 4 is the surface electron microscope image of Membrane 2 prepared in Example 2 of the present invention;

[0018] Figure 5 is the cross-sectional electron microscope image of Membrane 2 prepared in Example 2 of the present invention;

[0019] Figure 6 is the surface electron microscope image of Membrane 3 prepared in Example 3 of the present invention;

[0020] Figure 7 is the cross-sectional electron microscope image of Membrane 3 prepared in Example 3 of the present invention;

[0021] Figure 8 is the surface electron microscope image of Membrane 4 prepared in Example 4 of the present invention;

[0022] Figure 9 is the cross-sectional electron microscope image of Membrane 4 prepared in Example 4 of the present invention;

[0023] Figure 10 It is the surface electron microscope image of membrane 5 prepared in Example 5 of the present invention;

[0024] Figure 11 It is the cross-sectional electron microscope image of membrane 5 prepared in Example 5 of the present invention;

[0025] Figure 12 It is the surface electron microscope image of membrane 6 prepared in Comparative Example 1 of the present invention;

[0026] Figure 13 It is the cross-sectional electron microscope image of membrane 6 prepared in Comparative Example 1 of the present invention;

[0027] Figure 14 It is the surface electron microscope image of membrane 7 prepared in Comparative Example 2 of the present invention;

[0028] Figure 15 It is the cross-sectional electron microscope image of membrane 7 prepared in Comparative Example 2 of the present invention;

[0029] Figure 16 It is the comparison of the antibiotic desalination performance between membranes 1-5 of the present invention and comparative membranes 6 and 7;

[0030] Figure 17 It is the schematic diagram of the covalent organic framework nanosheet composite membrane assembled by MOF gel of the present invention. Detailed implementation manners

[0031] The present invention provides a covalent organic framework nanosheet composite membrane assembled by MOF gel for antibiotic desalination separation. The following is a further detailed description of the present invention in conjunction with the accompanying drawings and specific embodiments.

[0032] A covalent organic framework nanosheet composite membrane assembled by MOF gel described in the present invention specifically includes a variety of MOF gels, such as ZIF-8 gel, ZIF-67 gel, ZIF-7 gel, UiO-66 gel, etc. These gels are all prepared by solution self-assembly method; at the same time, COF nanosheets, including TpPa-SO3H, TpBd-SO3H, NABAPa-SO3H, etc. Among them, ZIF-8 gel and TpPa-SO3H nanosheets are preferred.

[0033] Example 1. Preparation of a covalent organic framework nanosheet composite membrane assembled by MOF gel, the steps are as follows:

[0034] Step 1) Preparation of MOF gel: Dissolve zinc nitrate hexahydrate (0.5 g) in methanol solution (20 mL), add a certain amount of triethylamine (0.2 mL), dissolve dimethylimidazole (1.1 g) in methanol (20 mL) solution, and finally mix the two solutions and stir for 1 hour, then collect by centrifugation to obtain ZIF-8 gel. Preparation of COF nanosheets: Dissolve 2,4,6-trihydroxy-1,3,5-benzenetricarboxaldehyde (21 mg) in dimethyl sulfoxide (5 mL) solution and disperse it by ultrasonic, denoted as aldehyde monomer solution; dissolve 2,5-benzenedisulfonic acid (28 mg) in dimethyl sulfoxide (5 mL) and disperse it by ultrasonic, denoted as amine monomer solution. Subsequently, mix the two solutions and react for 24 hours to obtain a dark brown solution, and dialyze it with a 30000 Da dialysis bag for 2 days to obtain a uniformly dispersed orange-yellow solution, namely TpPa-SO3H nanosheet dispersion.

[0035] Step 2) Dilution of a MOF gel-assembled covalent organic framework nanosheet: Dilute the dispersion prepared in Step 1) with deionized water to obtain a dispersion of MOF gel and COF nanosheets with a concentration of 0.05 mg mL-1. The transmission electron microscope images of the MOF gel and COF nanosheets are as Figure 1 shown.

[0036] Step 3) Preparation of a MOF gel-assembled covalent organic framework nanosheet composite membrane: Take 200 μL of ZIF-8 gel and 1 mL of COF nanosheets from the dispersion prepared in Step 2), and filter them onto the surface of a polyacrylonitrile porous polymer membrane by vacuum-assisted self-assembly method, and then dry at 30 °C for 24 hours to obtain a MOF gel-assembled covalent organic framework nanosheet composite membrane. Denote it as Membrane 1. Figure 2 Show the surface morphology of Membrane 1, Figure 3 which is the cross-sectional scanning electron microscope image of Membrane 1.

[0037] Use the above-mentioned MOF gel-assembled covalent organic framework nanosheet composite membrane for antibiotic desalination separation. Under the conditions of an operating temperature of 30 °C and a pressure of 2 bar, the water flux is 97.3 L m -2 h -1 bar -1 , and the antibiotic desalination separation factor is 16.5.

[0038] Example 2. Preparation of a MOF gel-assembled covalent organic framework nanosheet composite membrane. The steps are as follows:

[0039] Step 1) Prepare MOF gel and COF nanosheets. The preparation process is basically the same as that in Example 1.

[0040] Step 2) Preparation of a MOF gel-assembled covalent organic framework nanosheet composite membrane: The preparation process is basically the same as that in Example 1.

[0041] Step 3) Preparation of a MOF gel-assembled covalent organic framework nanosheet composite membrane: Take 400 μL of ZIF-8 gel and 1 mL of COF nanosheets from the dispersion obtained in Step 2), and filter them onto the surface of a polyacrylonitrile porous polymer membrane by vacuum-assisted self-assembly, and then dry at 30 °C for 24 hours to obtain a MOF gel-assembled covalent organic framework nanosheet composite membrane. Denote it as Membrane 2. Figure 4 Show the surface morphology of Membrane 2, Figure 5 which is the cross-sectional scanning electron micrograph of Membrane 2.

[0042] The above-mentioned MOF gel-assembled covalent organic framework nanosheet composite membrane is used for antibiotic desalination separation. Under the conditions of an operating temperature of 30 °C and a pressure of 2 bar, the water flux is 89.4 L m -2 h -1 bar -1 , and the antibiotic desalination separation factor is 16.6.

[0043] Example 3. Preparation of a MOF gel-assembled covalent organic framework nanosheet composite membrane, the steps are as follows:

[0044] Step 1) Preparation of MOF gel and COF nanosheets, the preparation process is basically the same as that in Example 1.

[0045] Step 2) Preparation of a MOF gel-assembled covalent organic framework nanosheet composite membrane: The preparation process is basically the same as that in Example 1.

[0046] Step 3) Preparation of a MOF gel-assembled covalent organic framework nanosheet composite membrane: Take 600 μL of ZIF-8 gel and 1 mL of COF nanosheets from the dispersion obtained in Step 2), and filter them onto the surface of a polyacrylonitrile porous polymer membrane by vacuum-assisted self-assembly, and then dry at 30 °C for 24 hours to obtain a MOF gel-assembled covalent organic framework nanosheet composite membrane. Denote it as Membrane 3. Figure 6 Show the surface morphology of Membrane 3, Figure 7 which is the cross-sectional scanning electron micrograph of Membrane 3.

[0047] The above-mentioned MOF gel-assembled covalent organic framework nanosheet composite membrane is used for antibiotic desalination separation. Under the conditions of an operating temperature of 30 °C and a pressure of 2 bar, the water flux is 84.9 L m -2 h -1 bar -1 , and the antibiotic desalination separation factor is 17.1.

[0048] Example 4. Preparation of a MOF gel-assembled covalent organic framework nanosheet composite membrane, the steps are as follows:

[0049] Step 1) Prepare MOF gel and COF nanosheets. The preparation process is basically the same as that in Example 1.

[0050] Step 2) Preparation of a composite membrane of MOF gel assembled with covalent organic framework nanosheets: The preparation process is basically the same as that in Example 1.

[0051] Step 3) Preparation of a composite membrane of MOF gel assembled with covalent organic framework nanosheets: Take 800 μL of ZIF-8 gel and 1 mL of COF nanosheets from the dispersion obtained in Step 2, and filter them onto the surface of a polyacrylonitrile porous polymer membrane by vacuum-assisted self-assembly method, and then dry at 30 °C for 24 hours to obtain a composite membrane of MOF gel assembled with covalent organic framework nanosheets. Denote it as Membrane 4. Figure 8 Show the surface morphology of Membrane 4, Figure 9 which is the cross-sectional scanning electron micrograph of Membrane 4.

[0052] Apply the above-mentioned composite membrane of MOF gel assembled with covalent organic framework nanosheets to antibiotic desalination separation. Under the conditions of an operating temperature of 30 °C and a pressure of 2 bar, the water flux is 77.8 L m -2 h -1 bar -1 , and the antibiotic desalination separation factor is 24.7.

[0053] Example 5. Preparation of a composite membrane of MOF gel assembled with covalent organic framework nanosheets. The steps are as follows:

[0054] Step 1) Prepare MOF gel and COF nanosheets. The preparation process is basically the same as that in Example 1.

[0055] Step 2) Preparation of a composite membrane of MOF gel assembled with covalent organic framework nanosheets: The preparation process is basically the same as that in Example 1.

[0056] Step 3) Preparation of a composite membrane of MOF gel assembled with covalent organic framework nanosheets: Take 800 μL of ZIF-8 gel and 1 mL of COF nanosheets from the dispersion obtained in Step 2, and filter them onto the surface of a polyacrylonitrile porous polymer membrane by vacuum-assisted self-assembly method, and then dry at 30 °C for 24 hours to obtain a composite membrane of MOF gel assembled with covalent organic framework nanosheets. Denote it as Membrane 5. Figure 10 Show the surface morphology of Membrane 5, Figure 11 which is the cross-sectional scanning electron micrograph of Membrane 5.

[0057] Apply the above-mentioned composite membrane of MOF gel assembled with covalent organic framework nanosheets to antibiotic desalination separation. Under the conditions of an operating temperature of 30 °C and a pressure of 2 bar, the water flux is 56.8 L m -2 h -1 bar -1, the desalination separation factor of the antibiotic is 14.7.

[0058] Comparative Example 1. Preparation of a MOF gel composite membrane, the steps are as follows:

[0059] Step 1) Preparation of MOF gel: Dissolve zinc nitrate hexahydrate (0.5 g) in methanol solution (20 mL), add a certain amount of triethylamine (0.2 mL), dissolve dimethylimidazole (1.1 g) in methanol (20 mL) solution, and finally mix the two solutions and stir for 1 hour, centrifuge and collect to obtain ZIF-8 gel.

[0060] Step 2) Preparation of a MOF gel dispersion: Dilution of a MOF gel assembled with covalent organic framework nanosheets: Dilute the dispersion obtained in Step 1) to deionized water to obtain a MOF gel dispersion with a concentration of 0.05 mg mL -1 .

[0061] Step 3) Preparation of a MOF gel composite membrane: Take 800 μL of the dispersion obtained in Step 2) and filter it onto the surface of a polyacrylonitrile porous polymer membrane by vacuum-assisted self-assembly method, and then dry it at 30 °C for 24 hours to obtain a MOF gel composite membrane. Denote it as Membrane 6. Figure 12 Show the surface morphology of Membrane 6, Figure 13 is the cross-sectional scanning electron micrograph of Membrane 6.

[0062] Use the above-mentioned MOF gel assembled with covalent organic framework nanosheet composite membrane for antibiotic desalination separation. Under the conditions of an operating temperature of 30 °C and a pressure of 2 bar, the water flux is 123 L m -2 h -1 bar -1 , and the desalination separation factor of the antibiotic is 1.8.

[0063] Comparative Example 2. Preparation of a COF composite membrane, the steps are as follows:

[0064] Step 1) Preparation of COF nanosheets: Dissolve 2,4,6-trihydroxy-1,3,5-benzenetricarboxaldehyde (21 mg) in dimethyl sulfoxide (5 mL) solution and ultrasonically disperse it, denoted as the aldehyde monomer solution; dissolve 2,5-benzenedisulfonic acid (28 mg) in dimethyl sulfoxide (5 mL) and ultrasonically disperse it, denoted as the amine monomer solution. Subsequently, mix the two solutions and react for 24 hours to obtain a dark brown solution, and dialyze it with a 30000 Da dialysis bag for 2 days to obtain a uniformly dispersed orange-yellow solution, that is, the TpPa-SO3H nanosheet dispersion.

[0065] Step 2) Preparation of a COF nanosheet dispersion: Dilute the dispersion obtained in Step 1) to deionized water to obtain a COF nanosheet dispersion with a concentration of 0.05 mg mL-1.

[0066] Step 3) Preparation of a COF nanosheet composite membrane: Take 1 mL of the dispersion obtained in Step 2) and filter it by vacuum-assisted self-assembly onto the surface of a polyacrylonitrile porous polymer membrane, and then dry it at 30 °C for 24 hours to obtain a COF nanosheet composite membrane. Denote it as Membrane 7. Figure 14 Show the surface morphology of Membrane 7, Figure 15 which is the cross-sectional scanning electron micrograph of Membrane 7.

[0067] When the above MOF gel-assembled covalent organic framework nanosheet composite membrane is used for antibiotic desalination separation, at an operating temperature of 30 °C and a pressure of 2 bar, the water flux is 119 L m -2 h -1 bar -1 , and the antibiotic desalination separation factor is 2.1.

[0068] By comparing the examples and comparative examples, the present invention provides a MOF gel-assembled COF nanosheet composite membrane and its preparation method, which is specifically used for antibiotic desalination separation. The composite membrane forms a dense membrane structure with high water flux and excellent selective separation performance by orderly stacking MOF gel and COF nanosheets. The three-dimensional network structure of the MOF gel provides an efficient ion transport channel and endows the membrane with good flexibility; while the COF nanosheets, due to their highly regular two-dimensional structure and adjustable pore size, significantly enhance the sieving ability for antibiotic molecules and effectively reduce the possibility of salt ion leakage. The synergistic effect of the two not only improves the mechanical strength of the membrane, but also significantly enhances the anti-fouling ability of the membrane, ensuring long-term stable separation performance. The preparation method of the present invention is simple and controllable, can be flexibly adapted to different combinations of MOF and COF materials, and has strong application and promotion potential. Especially in the field of antibiotic wastewater treatment, this composite membrane shows remarkable separation efficiency and excellent performance, indicating great application prospects in environmental protection and water resource recovery. Figure 16 Show the comparison data of Membranes 1-5 and the control membrane in terms of antibiotic removal efficiency and salt removal rate. Figure 17 This is the schematic diagram of the MOF gel-assembled COF nanosheet composite membrane of the present invention. By comparing the examples and comparative examples,

[0069] Although the present invention has been described in detail above with reference to the accompanying drawings, the present invention is not limited to the above specific embodiments. These embodiments are only illustrative and not restrictive definitions. Those of ordinary skill in the art, under the inspiration of the present invention and without departing from the core idea of the present invention, can still make various deformations or improvements, and these deformations and improvements all fall within the protection scope of the present invention.

Claims

1. A preparation and application of a MOF gel-assembled covalent organic framework nanosheet composite membrane, characterized in that: The steps include: (1) The composite membrane is composed of a metal organic framework (MOF) gel and a covalent organic framework (COF) nanosheet, wherein: the MOF gel is synthesized by a solution self-assembly method of metal ions and organic ligands, has a three-dimensional network structure, and can provide a supporting skeleton for the membrane; the COF nanosheet is prepared by a single-phase method, has a high specific surface area and selective separation performance, and acts as a selective separation layer of the membrane; (2) After the prepared MOF gel and COF nanosheet dispersion are mixed in proportion, they are evenly poured into a vacuum filtration device, and the solvent in the dispersion is gradually extracted under negative pressure conditions, and the MOF gel and COF nanosheets are evenly deposited on the porous polymer filter membrane to form a composite membrane; (3) MOF gel-assembled covalent organic framework composite membranes are used for antibiotic desalination and separation.

2. According to the technology described in claim 1, by preparing MOF gel and COF nanosheets and optimizing the mixing ratio, the antibiotic desalination mass transfer channel is optimized, and the antibiotic desalination separation factor and water flux are improved.

3. The technology according to claims 1 and 2, wherein the MOF gel and the COF nanosheet adopt a solution self-assembly method and a single-phase method, respectively. Specifically, the preparation method of the MOF gel is to weigh a certain mass of zinc nitrate hexahydrate and disperse it in a methanol solution, and add a certain amount of triethylamine to disperse it evenly; weigh a certain mass of dimethylimidazole and disperse it in a methanol solution, then stir the two mixed solutions for a certain time, centrifuge to obtain a ZIF-8 gel solution; the preparation method of the COF nanosheet is to dissolve a certain mass of aldehyde monomer and amine monomer in a certain amount of dimethyl sulfoxide, respectively, then slowly add the solution of the amine monomer dropwise to the solution of the aldehyde monomer, react at room temperature for 24 hours, and obtain a covalent organic framework nanosheet.

4. The method for preparing MOF gel and COF nanosheet according to claim 3, characterized in that: MOF gel and COF nanosheet colloidal solution were dispersed in a certain volume of deionized water, and the final concentration was 0.05 mg mL -1 .

5. The method for preparing a covalent organic framework composite membrane assembled by MOF gel according to claim 4, characterized in that: The MOF gel and COF nanosheet colloidal solution are deposited on the surface of a porous support polymer by a vacuum-assisted self-assembly method. The porous support membrane is any one of a variety of commercial ultrafiltration membranes such as polyacrylonitrile, polyethersulfone, polypropylene and polytetrafluoroethylene, preferably polyacrylonitrile.

6. Application of the MOF gel-assembled covalent organic framework composite membrane according to claims 1-5 in antibiotic desalination, wherein the water flux of the prepared composite membrane is 123-77.8 L m at room temperature and a pressure of 2 bar. -2 h-1bar -1 The antibiotic desalination separation factor is 1.8-24.7.

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