A desalination membrane, its preparation method and use
By constructing superhydrophilic channels on the surface of the desalination membrane, the balance between high flux and high antifouling properties of existing desalination membranes is solved, improving the membrane's hydrophilicity and antifouling performance and extending its service life.
Patent Information
- Application Number
- CN202511234171.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-01
- Publication Date
- 2025-12-16
- Estimated Expiration
- 2045-09-01
AI Technical Summary
Existing desalination membranes struggle to balance high flux and high antifouling properties, and their insufficient hydrophilicity leads to frequent membrane fouling, affecting their lifespan and energy consumption.
By forming a functional layer on the surface of a porous ultrafiltration membrane, and using interfacial polymerization reactions of polyamine monomers, zwitterionic polyhydroxy monomers, and acyl chloride monomers, superhydrophilic channels are constructed to form ester and amide bonds, thereby improving the membrane's hydrophilicity and antifouling properties.
This approach achieves improved membrane water flux and antifouling performance without reducing the desalination rate, and enhances membrane stability and service life.
Smart Images
Figure CN120714464B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of membrane separation technology, in particular to a desalination membrane and a preparation method and application thereof. BACKGROUND
[0002] Desalination membrane is the core component of seawater desalination. At present, the desalination membrane is mainly a thin layer composite (TFC) membrane composed of a polysulfone ultrafiltration base membrane supporting a polyamide (PA) active separation layer. The polyamide layer is formed by the interfacial polymerization reaction of amine monomers (m-phenylenediamine or piperazine) and trimesoyl chloride (TMC). Although such membranes have high desalination rate, there are still two major bottleneck problems: "flux-selectivity trade-off" limitation and pollution sensitivity caused by insufficient hydrophilicity. The hydrophobic surface of the polyamide layer easily adsorbs organic matter, microorganisms and inorganic salts, causing membrane pollution, flux decay and energy consumption, and frequent chemical cleaning, which shortens the service life of the membrane.
[0003] To break through the above limitations, current technologies attempt to modify through hydrophilic monomer copolymerization, zwitterionic material surface grafting and nano-channel construction. Although the introduction of hydroxyl monomers (such as tannic acid and gallic acid) in the interfacial polymerization aqueous phase can improve hydrophilicity, such monomers have low reactivity and are difficult to effectively embed in the polyamide network, and excessive introduction will damage the crosslinking degree and cause the desalination rate to decrease. Although the surface coating or grafting of zwitterionic polymers such as sulfobetaine can improve the anti-pollution property, the coating is easy to fall off, has poor stability, and the additional process step increases the manufacturing cost. In recent years, research has proposed to construct hydrophilic nano-channels in the separation layer to improve the selective transmission of water molecules, but the current method (such as nanoparticle doping) has interface defects, particle agglomeration and long-term operation dissolution risks. Therefore, it is urgent to develop a new type of TFC desalination membrane that can simultaneously achieve high flux and high anti-pollution property without sacrificing desalination rate, and the process needs to be compatible with industrial production. SUMMARY
[0004] The present application aims at the deficiencies of the prior art, and provides a desalination membrane and a preparation method and application thereof.
[0005] The purpose of the present application is achieved by the following technical solutions: In a first aspect, a desalination membrane is provided, comprising a porous ultrafiltration base membrane and a functional layer formed on the surface of the porous ultrafiltration base membrane; the functional layer is formed by the interfacial polymerization copolymerization and crosslinking of polyamine monomers, zwitterionic polyhydroxy monomers and acyl chloride monomers.
[0006] Specifically, the desalination membrane is prepared by increasing the zwitterionic polyhydroxyl monomer in the polyamine monomer and acyl chloride monomer for copolymerization, while forming ester bond and amide bond, the ester bond introduces increased chain segment freedom, which is conducive to the construction of more regular nanochannel; the introduction of zwitterionic group endows the membrane with superhydration characteristics, and constructs superhydrophilic channel which is conducive to water molecule transmission and salt rejection, thereby showing good desalination performance.
[0007] In an embodiment, the porous ultrafiltration base membrane is selected from at least one of polysulfone membrane, polyethersulfone membrane, polyimide membrane, polyacrylonitrile membrane, polyethylene membrane, and polypropylene membrane.
[0008] In an embodiment, the polyamine monomer is selected from at least one of m-phenylenediamine, p-phenylenediamine, o-phenylenediamine, piperazine, ethylenediamine, diethylenetriamine, triethylenetetramine, and polyethylenimine.
[0009] In an embodiment, the zwitterionic polyhydroxyl monomer is selected from at least one of polyhydroxyl compounds containing sulfobetaine group, carboxybetaine group, phosphobetaine group, sulfobetaine group, and trimethylamine N-oxide.
[0010] In a preferred embodiment, the zwitterionic polyhydroxyl monomer is selected from polyhydroxyl compounds containing trimethylamine N-oxide.
[0011] In a preferred embodiment, the zwitterionic polyhydroxyl monomer is selected from at least one of N-methyldiethanolamine N-oxide, N-benzyldiethanolamine N-oxide, di(hydroxyethyl)laurylamine oxide, and 1-[bis(2-hydroxyethyl)amino]hexadecan-2-ol N-oxide.
[0012] In an embodiment, the acyl chloride monomer is selected from at least one of trimesoyl chloride, isophthaloyl chloride, terephthaloyl chloride, phthaloyl chloride, 1,3,5-cyclohexane trimesoyl chloride, and biphenyl tetracarboxylic acid chloride.
[0013] In a second aspect, a preparation method of the desalination membrane is provided, comprising the following steps:
[0014] S1: providing a porous ultrafiltration base membrane;
[0015] S2: coating an alkaline aqueous solution containing polyamine monomer and zwitterionic polyhydroxyl monomer on the surface of the porous ultrafiltration base membrane to form an aqueous solution layer;
[0016] S3: coating an oil phase solution containing acyl chloride monomer on the surface of the aqueous solution layer, and performing interfacial polymerization reaction with the monomers in the aqueous solution layer to form a functional layer; after heat treatment, the desalination membrane is obtained.
[0017] In an embodiment, the basic reagent in the basic aqueous solution in step S2 is selected from at least one of triethylamine and sodium hydroxide.
[0018] In an embodiment, the pH of the basic aqueous solution in step S2 is 11.0-14.0.
[0019] In an embodiment, in the basic aqueous solution, the weight ratio of the polyamine monomer to the zwitterionic polyhydroxyl monomer is (9-1):(1-9), and the total concentration of the polyamine monomer and the zwitterionic polyhydroxyl monomer is 0.1-5.0 wt.%.
[0020] In an embodiment, after the formation of the aqueous solution layer in step S2, the method further comprises a step of removing excess basic aqueous solution.
[0021] In an embodiment, the solvent of the oil phase solution is selected from at least one of n-hexane, cyclohexane, Isopar G, Isopar E, n-heptane, and toluene.
[0022] In an embodiment, the concentration of the acyl chloride monomer in the oil phase solution is 0.01-1.0 wt.%.
[0023] In an embodiment, the time of the interfacial polymerization in step S3 is 10-300 s.
[0024] In an embodiment, after the formation of the functional layer in step S3, the method further comprises a step of removing excess oil phase solution.
[0025] In an embodiment, the temperature of the heat treatment in step S3 is 60-90℃, and the time is 5-15 min.
[0026] In a third aspect, the application provides use of the desalination membrane in any one of seawater desalination, brackish water desalination, wastewater treatment, material separation and concentration.
[0027] Specifically, the desalination membrane is used in a solution, and its application fields include but are not limited to seawater desalination, brackish water desalination, drinking water treatment, wastewater desalination treatment, industrial water desalination, agricultural water desalination, desalination in drilling or mining processes, etc.
[0028] The application has the advantages that the application efficiently and quickly prepares an amphoteric ion-based polyester amide desalination membrane by an interfacial polymerization method, the amphoteric ion-based polyester amide desalination membrane has good desalination performance, and the introduction of the super-hydrophilic amphoteric ion is expected to realize more excellent anti-pollution performance. BRIEF DESCRIPTION OF DRAWINGS
[0029] Figure 1 FIG. 1 is a graph showing the results of water flux and sodium chloride rejection rate tests of the desalination membrane prepared in Example 1 and Examples 6-9 of the present application. DETAILED DESCRIPTION
[0030] The exemplary embodiments will be described in detail herein with reference to the attached drawings. The description of the embodiments is merely representative of all embodiments consistent with the present application. Rather, they are merely examples of apparatus and methods consistent with some aspects of the present application as detailed in the appended claims.
[0031] The terminology used in the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. As used in the present application and the appended claims, the singular forms "a," "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will also be understood that the term "and / or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.
[0032] It will be understood that, although the terms first, second, third, etc. can be used herein to describe various information, the information should not be limited by these terms. These terms are used only to distinguish one piece of information from another. For example, a first information could be termed a second information, and, similarly, a second information could be termed a first information without departing from the scope of the present application. As used herein, the word "if' can be construed to mean "when" or "upon" or "in response to determining" depending on the context.
[0033] The present application will now be described in detail below with reference to the drawings. The features of the embodiments and implementation described below can be combined with each other as long as there is no conflict.
[0034] Example 1
[0035] In this example, a desalination membrane was prepared as follows:
[0036] (1) A porous polysulfone ultrafiltration base membrane was provided.
[0037] (2) A pH=13 sodium hydroxide aqueous phase solution containing 2.5 g of m-phenylenediamine and 2.5 g of N-methyldiethanolamine N-oxide (weight ratio of the two was 1:1) (total monomer concentration in the aqueous phase solution was 2.0 wt.%) was coated on the surface of the porous polysulfone ultrafiltration base membrane to form an aqueous phase solution layer. The excess aqueous phase solution was removed.
[0038] (3) A solution of trimesoyl chloride (0.1 wt.%) in n-hexane was coated on the surface of the aqueous solution layer treated in step (2) to react with the monomers in the aqueous solution layer by interfacial polymerization for 60 s to form a zwitterionic-based polyester amide functional layer on the surface of the base membrane. The excess oil phase solution was removed.
[0039] (4) The membrane prepared in step (3) was placed in a blast drying oven at 80 °C for heat treatment for 5 min to obtain a desalination membrane.
[0040] Example 2
[0041] A desalination membrane was prepared in this example as follows:
[0042] (1) A porous polysulfone ultrafiltration base membrane was provided.
[0043] (2) An aqueous solution of sodium hydroxide (pH = 13) containing 4.0 g of piperazine and 1.0 g of N-benzyldiethanolamine N-oxide (weight ratio of 4:1) (total monomer concentration in the aqueous solution was 5.0 wt.%) was coated on the surface of the porous polysulfone ultrafiltration base membrane to form an aqueous solution layer. The excess aqueous solution was removed.
[0044] (3) A solution of trimesoyl chloride (0.5 wt.%) in n-hexane was coated on the surface of the aqueous solution layer treated in step (2) to react with the monomers in the aqueous solution layer by interfacial polymerization for 30 s to form a zwitterionic-based polyester amide functional layer on the surface of the base membrane. The excess oil phase solution was removed.
[0045] (4) The membrane prepared in step (3) was placed in a blast drying oven at 80 °C for heat treatment for 10 min to obtain a desalination membrane.
[0046] Example 3
[0047] A desalination membrane was prepared in this example as follows:
[0048] (1) A porous polyethersulfone ultrafiltration base membrane was provided.
[0049] (2) An aqueous solution of triethylamine (pH = 13) containing 3.0 g of ethylenediamine and 2.0 g of di(hydroxyethyl)laurylamine oxide (weight ratio of 3:2) (total monomer concentration in the aqueous solution was 1.0 wt.%) was coated on the surface of the porous polyethersulfone ultrafiltration base membrane to form an aqueous solution layer. The excess aqueous solution was removed.
[0050] (3) Isopar G solution containing 1,3,5-cyclohexane tricarboxylic acid chloride (concentration of 0.05 wt.%) is coated on the surface of the water phase solution layer treated in step (2) to react with the monomers in the water phase solution layer by interfacial polymerization, and the reaction time is 120 s, thereby forming a zwitterionic polyester amide functional layer on the surface of the base membrane. Remove the excess oil phase solution.
[0051] (4) The membrane prepared in step (3) is placed in a blast drying oven at 80°C for heat treatment for 5 min, thereby obtaining a desalination membrane.
[0052] Example 4
[0053] A desalination membrane is prepared in this example as follows:
[0054] (1) A porous polyimide ultrafiltration base membrane is provided.
[0055] (2) A pH=14 triethylamine water phase solution containing 1.0 g of polyethyleneimine and 4.0 g of 1-[bis(2-hydroxyethyl)amino]hexadecan-2-ol N-oxide (weight ratio of the two is 1:4) (total monomer concentration in the water phase solution is 3.0 wt.%) is coated on the surface of the porous polyimide ultrafiltration base membrane to form a water phase solution layer. Remove the excess water phase solution.
[0056] (3) Isopar G solution containing 1,3,5-cyclohexane tricarboxylic acid chloride (concentration of 0.05 wt.%) is coated on the surface of the water phase solution layer treated in step (2) to react with the monomers in the water phase solution layer by interfacial polymerization, and the reaction time is 120 s, thereby forming a zwitterionic polyester amide functional layer on the surface of the base membrane. Remove the excess oil phase solution.
[0057] (4) The membrane prepared in step (3) is placed in a blast drying oven at 80°C for heat treatment for 5 min, thereby obtaining a desalination membrane.
[0058] Example 5
[0059] A desalination membrane is prepared in this example as follows:
[0060] (1) A porous polyacrylonitrile ultrafiltration base membrane is provided.
[0061] (2) A pH=11 triethylamine water phase solution containing 4.5 g of m-phenylenediamine and 0.5 g of N-benzyldiethanolamine N-oxide (weight ratio of the two is 9:1) (total monomer concentration in the water phase solution is 2.0 wt.%) is coated on the surface of the porous polyacrylonitrile ultrafiltration base membrane to form a water phase solution layer. Remove the excess water phase solution.
[0062] (3) Isomerized alkane Isopar G solution containing trimesoyl chloride (concentration of 0.1 wt.%) is coated on the surface of the water phase solution layer treated in step (2) to perform interfacial polymerization reaction with the monomers in the water phase solution layer, and the reaction time is 180 s, thereby forming a zwitterionic polyester amide functional layer on the surface of the base membrane. The excess oil phase solution is removed.
[0063] (4) The membrane prepared in step (3) is placed in a blast drying oven at 80 °C for heat treatment for 10 min, thereby obtaining a desalination membrane.
[0064] Example 6
[0065] A desalination membrane is prepared in this example, and in step (2), a pH = 13 sodium hydroxide water phase solution (total monomer concentration in the water phase solution is 2.0 wt.%) containing 4.0 g of m-phenylenediamine and 1.0 g of N-methyldiethanolamine N-oxide (weight ratio of the two is 4:1) is coated on the surface of the porous polysulfone ultrafiltration base membrane, and the rest of the preparation steps are the same as those of Example 1.
[0066] Example 7
[0067] A desalination membrane is prepared in this example, and in step (2), a pH = 13 sodium hydroxide water phase solution (total monomer concentration in the water phase solution is 2.0 wt.%) containing 3.0 g of m-phenylenediamine and 2.0 g of N-methyldiethanolamine N-oxide (weight ratio of the two is 3:2) is coated on the surface of the porous polysulfone ultrafiltration base membrane, and the rest of the preparation steps are the same as those of Example 1.
[0068] Example 8
[0069] A desalination membrane is prepared in this example, and in step (2), a pH = 13 sodium hydroxide water phase solution (total monomer concentration in the water phase solution is 2.0 wt.%) containing 2.0 g of m-phenylenediamine and 3.0 g of N-methyldiethanolamine N-oxide (weight ratio of the two is 2:3) is coated on the surface of the porous polysulfone ultrafiltration base membrane, and the rest of the preparation steps are the same as those of Example 1.
[0070] Example 9
[0071] A desalination membrane is prepared in this example, and in step (2), a pH = 13 sodium hydroxide water phase solution (total monomer concentration in the water phase solution is 2.0 wt.%) containing 1.0 g of m-phenylenediamine and 4.0 g of N-methyldiethanolamine N-oxide (weight ratio of the two is 1:4) is coated on the surface of the porous polysulfone ultrafiltration base membrane, and the rest of the preparation steps are the same as those of Example 1.
[0072] Comparative Example 1
[0073] A desalination membrane was prepared in this comparative example, which is different from Example 1 in that no zwitterionic polyhydroxy monomer was added in this comparative example. The preparation procedure is as follows:
[0074] (1) A porous polysulfone ultrafiltration base membrane was provided.
[0075] (2) A pH=13 sodium hydroxide aqueous solution containing 5.0 g of m-phenylenediamine (the total monomer concentration in the aqueous solution was 2.0 wt.%) was coated on the surface of the porous polysulfone ultrafiltration base membrane to form an aqueous solution layer. The excess aqueous solution was removed.
[0076] (3) A n-hexane solution containing trimesoyl chloride (the concentration was 0.1 wt.%) was coated on the surface of the aqueous solution layer after step (2) to perform interfacial polymerization reaction with the monomers in the aqueous solution layer, the reaction time was 60 s, and a polyamide functional layer was formed on the surface of the base membrane. The excess oil phase solution was removed.
[0077] (4) The membrane prepared in step (3) was placed in a blast drying oven at 80°C for heat treatment for 5 min to obtain a desalination membrane.
[0078] Comparative Example 2
[0079] A desalination membrane was prepared in this comparative example, which is different from Example 1 in that the non-zwitterionic polyesteramide desalination membrane was prepared in this comparative example, i.e., no zwitterionic polyhydroxy monomer was added. The preparation procedure is as follows:
[0080] (1) A porous polysulfone ultrafiltration base membrane was provided.
[0081] (2) A pH=13 sodium hydroxide aqueous solution containing 2.5 g of m-phenylenediamine and 2.5 g of m-dihydroxybenzene (the total monomer concentration in the aqueous solution was 2.0 wt.%) was coated on the surface of the porous polysulfone ultrafiltration base membrane to form an aqueous solution layer. The excess aqueous solution was removed.
[0082] (3) A n-hexane solution containing trimesoyl chloride (the concentration was 0.1 wt.%) was coated on the surface of the aqueous solution layer after step (2) to perform interfacial polymerization reaction with the monomers in the aqueous solution layer, the reaction time was 60 s, and a polyesteramide functional layer was formed on the surface of the base membrane. The excess oil phase solution was removed.
[0083] (4) The membrane prepared in step (3) was placed in a blast drying oven at 80°C for heat treatment for 5 min to obtain a desalination membrane.
[0084] Test Example
[0085] 1. Water flux and sodium chloride rejection test: Water flux and rejection are two important parameters for evaluating the performance of desalination membranes. The desalination membranes prepared in Examples 1-5 and Comparative Examples 1-2 were evaluated for performance by a cross-flow filtration device. Among them, the water flux (J) is defined as the volume of water permeating through a unit area per unit time under certain operating conditions, with the unit being L m -2 h -1 (LMH). The rejection (R) is defined as the difference between the salt concentration of the feed liquid and the salt concentration of the permeate divided by the salt concentration of the feed liquid under certain operating conditions.
[0086] The separation performance of the desalination membranes prepared in Examples 1-5 and Comparative Examples 1-2 was tested using the following operating conditions: the feed liquid was a 2000 ppm sodium chloride aqueous solution, the operating pressure was 1.5 MPa, the operating temperature was 25°C, and the pressure stabilization time was 60 min. The test results are shown in Table 1.
[0087] Table 1: Water flux and sodium chloride rejection of the desalination membranes of Examples 1-5 and Comparative Examples 1-2
[0088]
[0089] Table 1 lists the water flux and sodium chloride rejection of the desalination membranes of Examples 1-5 and Comparative Examples 1-2. As can be seen from the results, the zwitterionic-based polyester amide desalination membranes prepared in the present application have excellent desalination performance, with significantly improved water flux and sodium chloride rejection compared to polyamide membranes (Comparative Example 1) and non-zwitterionic-based polyester amide membranes (Comparative Example 2).
[0090] 2. The water flux and sodium chloride rejection of the desalination membranes prepared in Example 1 and Examples 6-9 (which differ in the mass ratio of m-phenylenediamine (MPD) and N-methyldiethanolamine N-oxide (MDEAO) in the water phase monomer) were also tested, and the results are shown in Figure 1 . Figure 1 As shown, when the mass ratio of the two is 1:1 (Example 1), the prepared desalination membrane has more excellent desalination performance.
[0091] It should be understood that the various forms of the flow shown above can be reordered, added to, or deleted from. For example, each step described in the present application can be performed in parallel, in sequence, or in a different order, as long as the desired results of the technical solutions of the present application can be achieved, and the present application is not limited herein.
[0092] In addition, the terms "first", "second", etc. are used only for the purpose of description, and should not be understood as indicating or implying relative importance or implying the number of the technical features indicated. Therefore, the features defined as "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "a plurality of" is two or more, unless otherwise specifically limited.
[0093] The above description is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.
Claims
1. A desalination membrane, characterized in that, The desalination membrane includes a porous ultrafiltration base membrane and a functional layer formed on the surface of the porous ultrafiltration base membrane; the functional layer is formed by copolymerization and crosslinking of polyamine monomers, zwitterionic polyhydroxy monomers and acyl chloride monomers through interfacial polymerization reaction; wherein, zwitterionic polyhydroxy monomers are added to the polyamine monomers and acyl chloride monomers used for copolymerization, and ester bonds and amide bonds are formed at the same time, and the introduction of ester bonds increases the degree of freedom of chain segments.
2. The desalination membrane according to claim 1, characterized in that, The porous ultrafiltration membrane is selected from at least one of polysulfone membrane, polyethersulfone membrane, polyimide membrane, polyacrylonitrile membrane, polyethylene membrane, and polypropylene membrane.
3. The desalination membrane according to claim 1, characterized in that, In the functional layer, the polyamine is selected from at least one of m-phenylenediamine, p-phenylenediamine, o-phenylenediamine, piperazine, ethylenediamine, diethylenetriamine, triethylenetetramine, and polyethyleneimine; The zwitterionic polyhydroxy monomer is selected from at least one of polyhydroxy compounds containing sulfonic acid betaine groups, carboxylic acid betaine groups, phosphate betaine groups, sulfonic acid betaine groups, and trimethylamine N-oxide. The acyl chloride monomer is selected from at least one of pyromellitic tricarboxylic acid chloride, isophthalic acid chloride, terephthalic acid chloride, orthophthalic acid chloride, 1,3,5-cyclohexanetricarboxylic acid chloride, and biphenyltetracarboxylic acid chloride.
4. A method for preparing a desalination membrane according to any one of claims 1-3, characterized in that, Includes the following steps: S1: Provides a porous ultrafiltration membrane base; S2: An alkaline aqueous solution containing polyamine monomers and zwitterionic polyhydroxy monomers is coated onto the surface of the porous ultrafiltration membrane to form an aqueous solution layer; S3: An oil phase solution containing acyl chloride monomer is coated onto the surface of the aqueous phase solution layer, and an interfacial polymerization reaction is carried out with the monomer in the aqueous phase solution layer to form a functional layer; after heat treatment, the desalination membrane is obtained.
5. The preparation method according to claim 4, characterized in that, The alkaline reagent in the alkaline aqueous solution in step S2 is selected from at least one of triethylamine and sodium hydroxide; the pH of the alkaline aqueous solution is 11.0~14.
0.
6. The preparation method according to claim 4, characterized in that, In the alkaline aqueous solution, the weight ratio of polyamine monomers to zwitterionic polyhydroxy monomers is (9~1):(1~9); the total concentration of polyamine monomers and zwitterionic polyhydroxy monomers is 0.1~5.0 wt.%.
7. The preparation method according to claim 4, characterized in that, The solvent of the oil phase solution is selected from at least one of n-hexane, cyclohexane, isoparaffin Isopar G, isoparaffin Isopar E, n-heptane, and toluene; the concentration of the acyl chloride monomer in the oil phase solution is 0.01~1.0 wt.%.
8. The preparation method according to claim 4, characterized in that, The time for the interfacial polymerization reaction in step S3 is 10~300 s.
9. The preparation method according to claim 4, characterized in that, The heat treatment in step S3 is performed at a temperature of 60~90℃ for 5~15 min.
10. The application of any one of the desalination membranes according to claims 1-3 in any one of seawater desalination, brackish water desalination, wastewater treatment, and material separation and concentration.