A synergistically enhanced desalination membrane and its preparation method and application

Abstract

The application provides a synergistically enhanced desalination membrane and a preparation method and application thereof, and relates to the field of membrane separation technology. The desalination membrane comprises 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 blending fluorine-containing polyhydroxy monomers, zwitterionic polyhydroxy monomers and polyamine monomers into an aqueous monomer system, and then copolymerizing and cross-linking the aqueous monomer system with an oil phase system containing acyl chloride monomers at an interface. The fluorine-containing monomers construct low-energy nanochannels in the membrane, improving the water molecule transmission efficiency. The zwitterionic monomers form a super-hydrophilic layer, significantly improving the anti-fouling performance of the membrane. The polyamine monomers participate in the cross-linking reaction, enhancing the compactness of the separation layer and effectively reducing the pore size, so as to realize the balance between high flux and high salt rejection rate. The obtained membrane has high flux, high selectivity and excellent anti-fouling performance, and is suitable for seawater desalination, brackish water desalination, saline-alkali water desalination, wastewater treatment and material separation and concentration.

Description

A synergistically enhanced desalination membrane, its preparation method and application Technical Field

[0001] This disclosure relates to the field of membrane separation technology, and in particular to a synergistically enhanced desalination membrane, its preparation method, and its application. Background Technology

[0002] Currently, polyamide (PA) thin-film composite (TFC) membranes are widely used in water treatment fields such as reverse osmosis and nanofiltration. A typical preparation method involves using polyamine monomers and acyl chloride monomers as reactants, which are polymerized at the interface to form an ultrathin separation layer on the surface of a porous membrane. Although these membranes possess high mechanical strength and desalination performance, a significant flux-selectivity trade-off remains: increasing the water flux often leads to a decrease in salt rejection. Furthermore, traditional polyamide membranes have a strong hydrophobic surface, easily adsorbing organic pollutants and microorganisms, resulting in flux decay and fouling accumulation during operation, severely impacting long-term stability.

[0003] To address these shortcomings, researchers have attempted to regulate membrane structure and performance by introducing functionalized monomers into interfacial polymerization. Polyesteramide (PEA) membranes constructed using monomers containing both amine and hydroxyl groups not only exhibit superior chemical stability and chlorine resistance compared to traditional polyamide (PA) membranes, but also enhance hydrophilicity and antifouling properties through intermolecular hydrogen bonding, thus achieving a performance balance between dense polyamide and loose polyester membranes. For example, introducing fluorinated monomers can form low-surface-energy transport channels within the membrane, thereby improving water molecule migration efficiency; introducing zwitterionic monomers can impart superhydrophilicity and antifouling properties to the membrane surface. However, single-type functional monomers are insufficient to simultaneously achieve high flux, salt rejection, and stability, and post-modification processes often lead to insufficient membrane adhesion or delamination. Therefore, there is an urgent need to develop a novel strategy that can synergistically construct fluorinated channels, a zwitterionic superhydrophilic layer, and a highly cross-linked dense structure in a one-step interfacial polymerization process, thereby simultaneously improving membrane separation efficiency and antifouling performance. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by providing a synergistically enhanced desalination membrane, its preparation method, and its application.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] In a first aspect, a synergistically enhanced 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 copolymerization and crosslinking of a fluorinated polyhydroxy monomer, a zwitterionic polyhydroxy monomer, and m-phenylenediamine with an acyl chloride monomer through an interfacial polymerization reaction.

[0007] Specifically, this synergistically enhanced desalination membrane introduces fluorinated polyhydroxy monomers and zwitterionic polyhydroxy monomers into a traditional polyamine monomer system, enabling the three to work synergistically during interfacial polymerization. The fluorinated monomers construct low-surface-energy nanochannels within the membrane, enhancing the migration rate of water molecules; the zwitterionic monomers form a superhydrophilic hydration layer, effectively inhibiting organic and biological contamination; the hydrophilic-hydrophobic interactions between the two promote microphase separation within the membrane layer, forming a regular and interconnected multi-scale channel structure. Simultaneously, m-phenylenediamine participates in the cross-linking reaction to form a dense polyamide framework, effectively reducing the pore size while improving the mechanical strength of the membrane layer, thus achieving a balance between high flux and high salt rejection rate.

[0008] In one embodiment, the porous ultrafiltration membrane is selected from at least one of polysulfone membrane, polyethersulfone membrane, polyimide membrane, polyacrylonitrile membrane, polyvinylidene fluoride membrane, polyethylene membrane, and polypropylene membrane.

[0009] In one embodiment, the fluorinated polyhydroxy monomer is selected from at least one of 4-fluororesorcinol, 5-fluororesorcinol, 5-trifluoromethyl-1,3-benzenediol, 2,3,5,6-tetrafluorohydroquinone, 3,6-dihydroxy-9-trifluoromethyl-9-phenyloxanthracene, 9-(trifluoromethyl)-9-(3-(trifluoromethyl)phenyl)-9H-oxanthracene-3,6-diol, 9-(3,5-bis(trifluoromethyl)phenyl)-9-(trifluoromethyl)-9H-xanthan-3,6-diol, and 4,4'-(2,2,2-trifluoro-1-phenylethane-1,1-diyl)bis(phenyl-1,2-diol).

[0010] In one embodiment, the zwitterionic polyhydroxy monomer is selected from at least one of polyhydroxy compounds consisting of sulfonate betaine groups, carboxybetaine groups, phosphate betaine groups, sulfonate betaine groups, and trimethylamine N-oxide.

[0011] In a preferred embodiment, the zwitterionic polyhydroxy monomer is selected from polyhydroxy compounds of trimethylamine N-oxide.

[0012] In a preferred embodiment, the zwitterionic polyhydroxy 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]hexadecane-2-ol N-oxide.

[0013] In one embodiment, the polyamine monomer is selected from at least one of m-phenylenediamine, piperazine, ethylenediamine, and polyethyleneimine, preferably m-phenylenediamine.

[0014] In one embodiment, 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, preferably pyromellitic tricarboxylic acid chloride.

[0015] Secondly, a method for preparing the aforementioned synergistically enhanced desalination membrane is provided, comprising the following steps:

[0016] S1: Provides a porous ultrafiltration membrane base;

[0017] S2: Dissolve fluorinated polyhydroxy monomers, zwitterionic polyhydroxy monomers and polyamine monomers in an alkaline aqueous phase to form an alkaline aqueous solution, and coat it on the surface of the porous ultrafiltration membrane to form an aqueous solution layer;

[0018] 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;

[0019] S4: After heat treatment, the synergistically enhanced desalination membrane is obtained.

[0020] In one embodiment, the alkaline reagent in the alkaline aqueous solution of step S2 is selected from at least one of triethylamine and sodium hydroxide.

[0021] In one embodiment, the pH of the alkaline aqueous solution in step S2 is 10.0 to 14.0, preferably 13.0.

[0022] In one embodiment, in the alkaline aqueous solution, the weight ratio of the fluorinated polyhydroxy monomer, the zwitterionic polyhydroxy monomer and the m-phenylenediamine in the aqueous phase is (1-3):(1-3):(4-8), and the total concentration of the three is 0.1~5.0 wt.%.

[0023] In one embodiment, after forming the aqueous solution layer, step S2 further includes the step of removing excess alkaline aqueous solution.

[0024] In one embodiment, the solvent of the oil phase solution is selected from at least one of n-hexane, cyclohexane, isoalkanes Isopar G, isoalkanes Isopar E, n-heptane, and toluene, preferably n-hexane or isoalkanes Isopar G.

[0025] In one embodiment, the concentration of acyl chloride monomer in the oil phase solution is 0.01~1.0 wt.%.

[0026] In one embodiment, the time for the interfacial polymerization reaction in step S3 is 10~300s.

[0027] In one embodiment, step S3, after forming the functional layer, further includes the step of removing excess oil phase solution.

[0028] In one embodiment, the heat treatment in step S3 is performed at a temperature of 60-90°C for 5-15 minutes.

[0029] Thirdly, the application of the aforementioned synergistically enhanced desalination membrane in any one of the following: seawater desalination, brackish water desalination, saline-alkali water desalination, wastewater treatment, and material separation and concentration.

[0030] Specifically, the aforementioned synergistically enhanced desalination membranes can be applied to processes such as seawater desalination, brackish water treatment, saline-alkali water desalination, drinking water purification, industrial wastewater reuse, and agricultural irrigation water desalination. They exhibit high throughput, high salt rejection rate, and excellent antifouling performance in solution separation.

[0031] According to one possible embodiment of the present invention, at least the following beneficial effects are achieved:

[0032] This invention prepares a synergistically enhanced desalination membrane through the synergistic interfacial polymerization of fluorinated polyhydroxy monomers, zwitterionic polyhydroxy monomers, and m-phenylenediamine, achieving the synergistic construction of fluorinated nanochannels and a zwitterionic superhydrophilic layer. The fluorinated monomers increase the water molecule transport rate within the membrane; the zwitterionic monomers form a stable hydration layer, significantly enhancing antifouling ability; the hydrophilic-hydrophobic interaction between the two promotes microphase separation in the membrane layer, constructing a regular channel structure; the zwitterionic monomers also act as surfactants, regulating monomer diffusion rate and interfacial polymerization behavior; m-phenylenediamine forms a highly cross-linked and dense framework, effectively reducing pore size and increasing salt rejection rate. Therefore, the membrane obtained by this invention possesses high flux, high selectivity, and excellent antifouling performance. The preparation process is simple and highly controllable, showing promising prospects for industrial application. Attached Figure Description

[0033] Figure 1 is a schematic diagram of the surface morphology and cross-sectional morphology of the synergistically enhanced desalination membrane prepared in Example 7 of the present invention. Detailed Implementation

[0034] To make the objectives, features, and advantages of this disclosure more apparent and understandable, the technical solutions in the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this disclosure, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this disclosure.

[0035] Example 1

[0036] This embodiment prepares a synergistically enhanced desalination membrane, as detailed below:

[0037] (1) Provide a porous polysulfone ultrafiltration membrane.

[0038] (2) Dissolve 2.5 g of 3,6-dihydroxy-9-trifluoromethyl-9-phenyloxanthracene, 2.5 g of N-methyldiethanolamine N-oxide, and 5.0 g of m-phenylenediamine in a sodium hydroxide solution with pH=13 to form an alkaline aqueous solution with a total concentration of 2.0 wt.%. Coat the surface of the porous polysulfone ultrafiltration membrane to form an aqueous solution layer. Remove excess aqueous solution.

[0039] (3) A hexane solution containing 0.1 wt.% trimesoyl chloride is coated onto the surface of the aqueous solution layer after step (2) and subjected to interfacial polymerization with the monomers in the aqueous solution layer for 60 s. Excess oil phase solution is removed.

[0040] (4) The membrane obtained in step (3) is placed in a forced-air drying oven at 80°C for 5 minutes for heat treatment to obtain a synergistically enhanced desalination membrane.

[0041] Example 2

[0042] This embodiment prepares a synergistically enhanced desalination membrane, as detailed below:

[0043] (1) Provide a porous polyethersulfone ultrafiltration base membrane.

[0044] (2) Dissolve 2.0 g of 4-fluororesorcinol, 3.0 g of N-benzyldiethanolamine N-oxide and 5.0 g of m-phenylenediamine in a triethylamine aqueous solution with pH=13 to form an alkaline aqueous solution with a total concentration of 2.0 wt.%, and coat it onto the surface of a porous polyethersulfone ultrafiltration membrane to form an aqueous solution layer. Remove excess aqueous solution.

[0045] (3) A cyclohexane solution containing 0.05 wt.% 1,3,5-cyclohexanetricarboxylic acid chloride is coated onto the surface of the aqueous solution layer after step (2) and subjected to interfacial polymerization with the monomers in the aqueous solution layer for 90 s. Excess oil phase solution is removed.

[0046] (4) The membrane obtained in step (3) is placed in a 70°C drying oven for 8 minutes of heat treatment to obtain a synergistically enhanced desalination membrane.

[0047] Example 3

[0048] This embodiment prepares a synergistically enhanced desalination membrane, as detailed below:

[0049] (1) Provide a porous polyimide ultrafiltration membrane.

[0050] (2) Dissolve 3.0 g of 5-trifluoromethyl-1,3-benzenediol, 2.0 g of di(hydroxyethyl)laurylamine oxide and 5.0 g of m-phenylenediamine in a sodium hydroxide solution with pH=13 to form an alkaline aqueous solution with a total concentration of 2.5 wt.%. Coat the surface of the porous polyimide ultrafiltration membrane to form an aqueous solution layer. Remove excess aqueous solution.

[0051] (3) Coat the surface of the aqueous solution layer treated in step (2) with an isoparaffinic alkane Isopar G solution containing 0.1 wt.% trimesoyl chloride, and perform interfacial polymerization reaction with the monomers in the aqueous solution layer for 100 s. Remove excess oil phase solution.

[0052] (4) The membrane obtained in step (3) is placed in a forced-air drying oven at 85°C for 10 min of heat treatment to obtain a synergistically enhanced desalination membrane.

[0053] Example 4

[0054] This embodiment prepares a synergistically enhanced desalination membrane, as detailed below:

[0055] (1) Provide a porous polyvinylidene fluoride (PVDF) ultrafiltration base membrane.

[0056] (2) Dissolve 2.5g of 5-fluororesorcinol, 2.5g of 1-[bis(2-hydroxyethyl)amino]hexadecane-2-ol N-oxide, and 5.0g of m-phenylenediamine in a triethylamine aqueous solution with pH=12 to form an alkaline aqueous solution with a total concentration of 2.0wt.%. Coat the solution onto the surface of a porous polyvinylidene fluoride ultrafiltration membrane to form an aqueous solution layer. Remove excess aqueous solution.

[0057] (3) A heptane solution containing 0.1 wt.% biphenyltetramethylchlorohydrin is coated onto the surface of the aqueous solution layer after step (2) and subjected to interfacial polymerization with the monomers in the aqueous solution layer for 120 s. Excess oil solution is removed.

[0058] (4) The membrane obtained in step (3) is placed in a forced-air drying oven at 80°C for 10 min of heat treatment to obtain a synergistically enhanced desalination membrane.

[0059] Example 5

[0060] This embodiment prepares a synergistically enhanced desalination membrane, as detailed below:

[0061] (1) Provide a porous polyethersulfone ultrafiltration base membrane.

[0062] (2) Dissolve 3.0 g of 2,3,5,6-tetrafluorohydroquinone, 2.0 g of N-methyldiethanolamine N-oxide, and 5.0 g of m-phenylenediamine in a sodium hydroxide solution with pH=13 to form an alkaline aqueous solution with a total concentration of 3.0 wt.%. Coat the solution onto the surface of a porous polyethersulfone ultrafiltration membrane to form an aqueous solution layer. Remove excess aqueous solution.

[0063] (3) A hexane solution containing 0.1 wt.% trimesoyl chloride is coated onto the surface of the aqueous solution layer after step (2) and subjected to interfacial polymerization with the monomers in the aqueous solution layer for 90 s. Excess oil phase solution is removed.

[0064] (4) The membrane obtained in step (3) is placed in a forced-air drying oven at 85°C for 5 minutes for heat treatment to obtain a synergistically enhanced desalination membrane.

[0065] Example 6

[0066] In this embodiment, a synergistically enhanced desalination membrane was prepared. In step (2), a sodium hydroxide aqueous solution with pH=13 containing 3.0 g of 3,6-dihydroxy-9-trifluoromethyl-9-phenyloxanthracene, 1.0 g of N-methyldiethanolamine N-oxide and 6.0 g of m-phenylenediamine (the weight ratio of the three is 3:1:6) (the total monomer concentration in the aqueous solution is 2.0 wt.%) was coated on the surface of the porous polysulfone ultrafiltration membrane. The rest of the preparation steps were the same as those in Example 1.

[0067] Example 7

[0068] In this embodiment, a synergistically enhanced desalination membrane was prepared. In step (2), a sodium hydroxide aqueous solution with pH=13 containing 2.0 g of 3,6-dihydroxy-9-trifluoromethyl-9-phenyloxanthracene, 2.0 g of N-methyldiethanolamine N-oxide and 6.0 g of m-phenylenediamine (the weight ratio of the three is 2:2:6) (the total monomer concentration in the aqueous solution is 2.0 wt.%) was coated on the surface of the porous polysulfone ultrafiltration membrane. The rest of the preparation steps were the same as those in Example 1.

[0069] Example 8

[0070] In this embodiment, a synergistically enhanced desalination membrane was prepared. In step (2), a sodium hydroxide aqueous solution with pH=13 containing 1.0 g of 3,6-dihydroxy-9-trifluoromethyl-9-phenyloxanthracene, 3.0 g of N-methyldiethanolamine N-oxide and 6.0 g of m-phenylenediamine (the weight ratio of the three is 1:3:6) (the total monomer concentration in the aqueous solution is 2.0 wt.%) was coated on the surface of the porous polysulfone ultrafiltration membrane. The rest of the preparation steps were the same as those in Example 1.

[0071] Example 9

[0072] In this embodiment, a synergistically enhanced desalination membrane was prepared. In step (2), a sodium hydroxide aqueous solution with pH=13 containing 1.0 g of 3,6-dihydroxy-9-trifluoromethyl-9-phenyloxanthracene, 1.0 g of N-methyldiethanolamine N-oxide and 8.0 g of m-phenylenediamine (the weight ratio of the three is 1:1:8) (the total monomer concentration in the aqueous solution is 2.0 wt.%) was coated on the surface of the porous polysulfone ultrafiltration membrane. The rest of the preparation steps were the same as those in Example 1.

[0073] Comparative Example 1

[0074] This comparative example prepared a synergistically enhanced desalination membrane. The difference from Example 1 is that this comparative example did not include fluorine-containing monomers or zwitterionic monomers. Details are as follows:

[0075] (1) Provide a porous polysulfone ultrafiltration membrane.

[0076] (2) A sodium hydroxide aqueous solution containing 10.0 g m-phenylenediamine at pH=13 (total monomer concentration in the aqueous solution is 2.0 wt.%) was coated onto the surface of a porous polysulfone ultrafiltration membrane to form an aqueous solution layer. Excess aqueous solution was removed.

[0077] (3) A hexane solution containing trimesoyl chloride (concentration of 0.1 wt.%) is coated onto the surface of the aqueous solution layer after step (2) and subjected to interfacial polymerization reaction with the monomers in the aqueous solution layer for 60 s to form a polyamide functional layer on the base film surface. Excess oil phase solution is removed.

[0078] (4) The membrane obtained in step (3) is placed in a forced-air drying oven at 80°C for 5 minutes for heat treatment to obtain a synergistically enhanced desalination membrane.

[0079] Comparative Example 2

[0080] This comparative example prepared a synergistically enhanced desalination membrane. The difference from Example 1 is that this comparative example added a fluorine-containing monomer but did not add a zwitterionic monomer. Details are as follows:

[0081] (1) Provide a porous polysulfone ultrafiltration membrane.

[0082] (2) Dissolve 2.5g of 3,6-dihydroxy-9-trifluoromethyl-9-phenyloxanthracene and 7.5g of m-phenylenediamine in a sodium hydroxide solution with pH=13 to form an alkaline aqueous solution with a total concentration of 2.0wt.%, which is then coated onto the surface of a porous polysulfone ultrafiltration membrane to form an aqueous solution layer. Remove excess aqueous solution.

[0083] (3) A hexane solution containing 0.1 wt.% trimesoyl chloride is coated onto the surface of the aqueous solution layer after step (2) and subjected to interfacial polymerization with the monomers in the aqueous solution layer for 60 s. Excess oil phase solution is removed.

[0084] (4) The membrane obtained in step (3) is placed in a forced-air drying oven at 80°C for 5 minutes for heat treatment to obtain a synergistically enhanced desalination membrane.

[0085] Test case

[0086] 1. Water flux and sodium chloride rejection rate test: Water flux and rejection rate are two important parameters for evaluating the performance of synergistically enhanced desalination membranes. The performance of the synergistically enhanced desalination membranes prepared in Examples 1-5 and Comparative Examples 1-2 was evaluated using a cross-flow filtration device. Water flux (J) is defined as the volume of water that permeates through a unit area per unit time under certain operating conditions, expressed in mL / m³. -2 h -1 Rejection (R) is defined as the difference between the feed solution salt concentration and the permeate salt concentration under certain operating conditions, divided by the feed solution salt concentration.

[0087] The separation performance of the synergistically enhanced desalination membranes prepared in Examples 1-5 and Comparative Examples 1-2 was tested under the following operating conditions: feed solution was 2000 ppm sodium chloride aqueous solution, operating pressure was 1.55 MPa, operating temperature was 25 °C, and pressure stabilization time was 60 min. The test results are shown in Table 1.

[0088] Table 1: Water flux and sodium chloride rejection of the synergistically enhanced desalination membranes in Examples 1-5 and Comparative Examples 1-2

[0089]

[0090] Table 1 lists the water flux and sodium chloride rejection rate of the desalination membranes in Examples 1-5 and Comparative Examples 1-2. The results show that the zwitterionic polyesteramide desalination membrane prepared in this application has excellent desalination performance, exhibiting significantly improved water flux and sodium chloride rejection rate compared to the polyamide membrane (Comparative Example 1) and the non-zwitterionic polyesteramide membrane (Comparative Example 2).

[0091] 2. The water flux and sodium chloride rejection of the synergistically enhanced desalination membranes prepared in Examples 1 and 6-9 (the mass ratios of 3,6-dihydroxy-9-trifluoromethyl-9-phenyloxanthracene (3FR), N-methyldiethanolamine N-oxide (MDEAO), and m-phenylenediamine (MPD) in the aqueous phase monomers of these examples were also tested. The results are shown in Table 2. Table 2 shows that when the mass ratio of the two components is 2:2:6 (Example 7), the prepared synergistically enhanced desalination membrane exhibits superior desalination performance. The morphology of Example 7 is shown in Figure 1. The left image in Figure 1 shows the surface morphology of Example 7, and the inset in the upper left corner of the left image is a photograph of the sample after testing in Example 7. The right image in Figure 1 shows the cross-sectional morphology of Example 7; it demonstrates that the membrane surface still retains the typical "ridge-valley" structure of polyamide, and the abundant specific surface area is beneficial for water permeation.

[0092] Table 2: Water flux and sodium chloride rejection rate of the synergistically enhanced desalination membranes in Examples 1 and 6-9

[0093]

[0094] It should be understood that the various forms of processes shown above can be used to rearrange, add, or delete steps. For example, the steps described in this disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this disclosure can be achieved, and this is not limited herein.

[0095] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this disclosure, "a plurality of" means two or more, unless otherwise explicitly specified.

[0096] The above description is merely a specific embodiment of this disclosure, but the scope of protection of this disclosure is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope of the claims.

Claims

1. A synergistically enhanced desalination membrane, characterized in that, The synergistically enhanced desalination membrane includes a porous ultrafiltration base membrane and a functional layer formed on its surface; the functional layer is formed by copolymerization and crosslinking of fluorinated polyhydroxy monomers, zwitterionic polyhydroxy monomers, and polyamine monomers with acyl chloride monomers in the same aqueous system via a one-step interfacial polymerization reaction.

2. The synergistically enhanced 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, polyvinylidene fluoride membrane, polyethylene membrane, and polypropylene membrane.

3. The synergistically enhanced desalination membrane according to claim 1, characterized in that, In the functional layer, the fluorinated polyhydroxy monomer is selected from 4-fluororesorcinol, 5-fluororesorcinol, 5-trifluoromethyl-1,3-benzenediol, 2,3,5,6-tetrafluorohydroquinone, 3,6-dihydroxy-9-trifluoromethyl-9-phenyloxanthracene, 9-(trifluoromethyl)-9-(3-(trifluoromethyl)phenyl)-9H-oxanthracene-3,6-diol, 9-(3,5-bis(trifluoromethyl)phenyl)-9-(trifluoromethyl)-9H-xanthan-3,6-diol, 4,4'-(2,2,2-trifluoro -1-phenylethane-1,1-diyl)bis(phenyl-1,2-diol); the zwitterionic polyhydroxy monomer is selected from at least one of polyhydroxy compounds containing sulfonate betaine groups, carboxybetaine groups, phosphate betaine groups, sulfobetaine groups, and trimethylamine N-oxide; the polyamine monomer is selected from at least one of m-phenylenediamine, piperazine, ethylenediamine, and polyethyleneimine; the acyl chloride monomer is selected from at least one of pyromellitic tricarboxylic acid chloride, 1,3,5-cyclohexanetricarboxylic acid chloride, and biphenyltetracarboxylic acid chloride.

4. A method for preparing the synergistically enhanced desalination membrane according to any one of claims 1 to 3, characterized in that, Includes the following steps: S1: Provides a porous ultrafiltration membrane base; S2: Dissolve fluorinated polyhydroxy monomers, zwitterionic polyhydroxy monomers and polyamine monomers in an alkaline aqueous phase to form an alkaline aqueous solution, and coat it on the surface of the porous ultrafiltration membrane to form an aqueous solution layer; S3: Coat the surface of the aqueous solution layer with an oil phase solution containing acyl chloride monomers, and perform a one-step interfacial polymerization reaction with the monomers in the aqueous solution layer to form a functional layer; S4: After heat treatment, the synergistically enhanced 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 10.0~14.

0.

6. The preparation method according to claim 4, characterized in that, In the alkaline aqueous solution, the mass ratio of fluorinated monomer, zwitterionic monomer and polyamine monomer is (1-3):(1-3):(4-8); the total concentration of aqueous monomer 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 10~300s.

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 minutes.

10. The application of the synergistic enhancement desalination membrane according to any one of claims 1 to 3 in any one of seawater desalination, brackish water desalination, saline-alkali water desalination, wastewater treatment, and material separation and concentration.

Images