High-flux high-boron-removal reverse osmosis membrane and preparation method thereof

Abstract

The invention discloses a high-flux high-boron-removal reverse osmosis membrane and a preparation method thereof. The reverse osmosis membrane is prepared from the following raw materials: a solvent, a solute and a base membrane material, the solvent comprises a dipolar aprotic solvent / water mixed solvent and normal hexane; the solute comprises an aromatic acyl chloride monomer, an aromatic diamine monomer and an amino-modified natural polyhydroxy polymer; and the base membrane material is a polysulfone ultrafiltration membrane. The preparation method comprises the following steps: dissolving an aromatic acyl chloride monomer in n-hexane to obtain a solution A, dissolving an amino-modified natural polyhydroxy polymer in a dipolar aprotic solvent to obtain a solution B, then dissolving an aromatic diamine monomer in the solution B, then adding water to obtain a solution C, then immersing the base membrane in the solution C, and carrying out vacuum drying to obtain the composite membrane. After standing, removing the residual solution C on the surface of the base membrane, and immersing the base membrane into the solution A to carry out interfacial polymerization reaction; and carrying out post-treatment on the reacted membrane to obtain the reverse osmosis membrane. By adopting an organic-organic interface, the technical problem that the boron removal rate and flux of the existing polyamide reverse osmosis membrane are balanced is solved.

Description

Technical Field

[0001] The invention relates to a permeation membrane and a preparation method thereof, in particular to a high-flux high-boron removal reverse osmosis membrane and a preparation method thereof. Background Art

[0002] During the use of ultrapure water, there are strict requirements on the boron content in the water. In the preparation stage of ultrapure water, the raw water needs to be deborated. Ultrapure water systems usually use ion exchange resins and reverse osmosis membrane components to remove boron. However, when using anion exchange resins to remove boron, the selectivity of anion resins for boron is extremely low, and boron is easily replaced by other ions, which greatly reduces the efficiency of ion exchange resins in removing boron.

[0003] At present, the boron removal rate of reverse osmosis membrane under neutral conditions is low, at about 60%-85%, which is mainly limited by the existence form of boron. Boron usually exists in acidic and neutral water in the form of boric acid. Boric acid molecules are not charged, and reverse osmosis membranes cannot remove boric acid through the charge repulsion mechanism; boric acid in water has a molecular diameter of only 2.75 angstroms, which is smaller than the aggregation pore radius (3.5-4.5 angstroms) and is within the separation range of network pores (1-3 angstroms). The use of pore size screening mechanism to remove boron has high requirements for the pore size distribution and density of reverse osmosis membranes. The patent for deboronized reverse osmosis membrane "CN115608172A-"A seawater deboronized reverse osmosis membrane and its preparation method and application"" involves the preparation method of deboronized seawater desalination membrane. Its interfacial polymerization process occurs at the water-organic interface, and the aqueous phase monomer diffuses into the organic phase to form a separation layer. Its diffusion rate is uncontrollable, and the density of the separation layer and the pore size distribution of the membrane are difficult to regulate. The improvement of the deboronization rate and flux depends on the deboronization additive. There are compatibility issues between the additive and the separation layer, and the industrial value is not high. In addition, the transmission mode of boric acid in the membrane is similar to that of water, and it has a strong binding force with water and can easily pass through the reverse osmosis membrane.

[0004] The low boron removal rate of ordinary pure water series reverse osmosis membranes will lead to high-load operation of the back-end treatment system. In order to make the boron concentration meet the usage requirements, an additional boron removal resin process will be added, which will increase the operating cost of the ultrapure water system. A better preparation method is urgently needed to obtain reverse osmosis membrane products with high flux and high boron removal performance. Summary of the invention

[0005] Purpose of the invention: The purpose of the present invention is to provide a high-flux and high-boron removal reverse osmosis membrane to solve the technical problem that there is a balance between the boron removal rate and the flux of the existing polyamide reverse osmosis membrane;

[0006] The second object of the present invention is to provide a method for preparing the above-mentioned high-flux and high-boron removal reverse osmosis membrane.

[0007] Technical solution: The high-flux and high-boron removal reverse osmosis membrane described in the present invention is prepared from raw materials including solvent, solute and base membrane material; the solvent includes a dipolar aprotic solvent / water mixed solvent and n-hexane; the solute includes aromatic acyl chloride monomers, aromatic diamine monomers, and amino-modified natural polyhydroxy polymers; and the base membrane material is a polysulfone ultrafiltration membrane.

[0008] The amino-modified natural polyhydroxy polymer is a polysaccharide amino-modified polymer, and the amino-modified natural polyhydroxy polymer has an amino group and multiple hydroxyl functional groups; specifically, it is at least one of aminodextran, aminocellulose or aminostarch.

[0009] As the core component in the formula of the present invention, the amino-modified natural polyhydroxy polymer is regarded as an additive with good compatibility. This type of additive has a large polarity. According to the principle of similar dissolving, it can be dissolved in polar solvents and slightly soluble in low-polarity solvent n-hexane. Therefore, in the process of polymerization reaction between diamine monomer and acyl chloride monomer, the diffusion tendency of this type of additive to the n-hexane interface is weak and the diffusion rate is low. When the interfacial polymerization reaction occurs, a small part of the polymer located at the interface participates in the polymerization reaction by means of active ammonia, and most of it stays in the polar solvent. When the polymerization reaction is completed, the formed polyamide layer is subjected to heat treatment, and the n-hexane solvent and the dipolar aprotic solvent evaporate and leave the inside of the membrane, and the polyamide network shrinks. The amino-modified natural polyhydroxy polymer will be embedded in the polyamide layer as an additive.

[0010] Among them, after the dipolar aprotic solvent and deionized water are mutually soluble in a certain proportion, the diffusion of TMC into the dipolar aprotic solvent will be hindered without affecting the solubility of the amino-modified natural polyhydroxy polymer, and the interfacial polymerization reaction will be controlled to proceed at the organic-organic interface, which is conducive to the formation of a complete separation layer at the interface; secondly, the reverse diffusion of TMC into the amine solution will still occur, and the nanobubbles generated by the reaction will cause more free volume in the separation layer, providing a higher permeation flux. The dipolar aprotic solvent is at least one of the polar solvents dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), and N-methylpyrrolidone (NMP); the aromatic acyl chloride monomer is trimesoyl chloride (TMC) monomer; the aromatic diamine monomer is a phenylenediamine monomer, and the phenylenediamine monomer is at least one of o-phenylenediamine, m-phenylenediamine (MPD), and p-phenylenediamine.

[0011] The solvent for dissolving the acyl chloride monomer is n-hexane; the mass fraction of the aromatic acyl chloride monomer in n-hexane is 0.1-0.4 wt %.

[0012] The aromatic diamine monomer and the amino-modified natural polyhydroxy polymer are dissolved together in a dipole aprotic solvent / water mixed solvent, wherein the mass fraction of the aromatic diamine monomer in the dipole aprotic solvent / water mixed solvent is 0.5-4wt%, and the mass fraction of the amino-modified natural polyhydroxy polymer in the dipole aprotic solvent / water mixed solvent is 0.1-2wt%; and the volume proportion of water in the dipole aprotic solvent / water mixed solvent is 20-50%.

[0013] Among them, the amino-modified natural polyhydroxy polymer has strong hydrophilicity brought by polyhydroxy groups and has amino groups with high reactivity. The polymer at the interface can react with acyl chloride monomers to regulate the polymerization reaction process at the interface; the polymer in the solution forms nano-scale particles, which can adjust the pore size inside the separation layer, realize the regulation of the membrane surface structure and the pore size inside the membrane, and improve the deboronization performance of the reverse osmosis membrane.

[0014] Taking aminodextran as an example, when it is used as an additive, the possible reactions during the interfacial polymerization process are as follows:

[0015] (1) A polymerization reaction between a diamine monomer and an acyl chloride monomer to form a polyamide layer. The diamine monomer is exemplified by m-phenylenediamine.

[0016]

[0017] (2) The reaction of aminodextran with an acyl chloride monomer, wherein the acyl chloride monomer can be in the form of a trichloride, or a monochloride or dichloride polymer after an incomplete reaction with a diamine monomer.

[0018]

[0019] Among them, (1) is the main reaction during the interfacial polymerization process. During this reaction process, the three acyl chloride groups on most acyl chloride monomers are fully cross-linked with the amino group to form a dense polyamide separation layer, but there may still be some incompletely reacted acyl chloride groups; (2) is the condensation reaction between the terminal amino group in aminodextran and the acyl chloride group. The acyl chloride in this process can be a monomer in the form of triacyl chloride or a monoacyl chloride or diacyl chloride polymer. The amino group participating in the reaction in this process is the terminal amino group. This reaction can disrupt the polymerization process at the interface, thereby adjusting the morphology of the surface of the separation layer. Most of the aminodextran will be embedded in the separation layer as an additive to adjust the internal pore size of the polyamide separation layer, form more network pores, and improve the interception effect of boron. Among them, Dex-NH2 is formed when a hydroxyl group in dextran is replaced by an amino group. When ethylenediamine is used as a replacement, its structural formula is:

[0020]

[0021] Furthermore, the amino-modified natural polyhydroxy polymer embedded in the separation layer has polyhydroxy functional groups and amino groups, wherein the polyhydroxy functional groups have a specific adsorption effect on boric acid, the resistance of boron passing through the membrane is increased, and the reverse osmosis membrane has a better removal effect on boron.

[0022] The method for preparing the high-flux high-boron removal reverse osmosis membrane comprises the following steps:

[0023] (1) dissolving an aromatic acyl chloride monomer in n-hexane to obtain a solution A;

[0024] (2) dissolving the amino-modified natural polyhydroxy polymer in a dipolar aprotic solvent to obtain a solution B;

[0025] (3) dissolving an aromatic diamine monomer into solution B, and then adding water to obtain solution C;

[0026] (4) Immerse the basement membrane in solution C and let it stand;

[0027] (5) After removing the residual solution C on the surface of the basement membrane, the basement membrane is immersed in solution A to allow interfacial polymerization to react for a period of time;

[0028] (6) The membrane after the reaction is post-treated to obtain a reverse osmosis membrane.

[0029] Preferably, in step (1), the proportion of aromatic acyl chloride monomer is 0.1wt%-0.4wt%, the stirring time is 20-60min, and the ultrasonic time is 15min.

[0030] Preferably, the amino-modified natural polyhydroxy polymer in step (2) uses one or more of aminodextran, aminocellulose and aminostarch; the stirring time during dissolution is 2-4 hours, and the ultrasonic time is 30 minutes.

[0031] Preferably, the aromatic diamine monomer in step (3) is p-phenylenediamine, the stirring time during dissolution is 30-60 min, and the ultrasonic time is 10 min; the ultrasonic stage should be selected before step (4), and step (4) should be performed immediately after completion.

[0032] Preferably, in the solution C obtained in step (3), the amino-modified natural polyhydroxy polymer accounts for 0.1wt%-2wt%, the aromatic diamine monomer accounts for 0.5wt%-4wt%; and the percentage of water in the dipolar aprotic solvent / water mixed solvent is 20-50% (v / v).

[0033] Preferably, the base membrane in step (4) is a polysulfone ultrafiltration membrane with a molecular weight cutoff of 30-150 kDa. Before immersion, an air knife is used to remove residual water droplets on the surface of the base membrane. The residence time of the base membrane in solution C is 1-20 min.

[0034] Preferably, in step (5), residual solution C on the surface of the base film is blown away by an air knife, and the reaction time of immersion in solution A is 0.5-2 min.

[0035] Preferably, the post-treatment step in step (6) is divided into two steps. The first step is to use n-hexane to clean the membrane surface for 10-60 seconds; the second step is a heat treatment method with a heat treatment temperature of 60-100°C and a heat treatment time of 1-3 minutes.

[0036] Principle of the invention: The present invention provides a high-flux, high-boron removal reverse osmosis membrane suitable for ultrapure water systems, which is a polyamide composite membrane. The core of the membrane is that through interfacial polymerization at the organic-organic interface, acyl chloride monomers can reversibly diffuse into an amine monomer solution, and the diffusion rate of the acyl chloride monomers will be controlled by the water component in the amine solution. Therefore, the density and pore size distribution of the separation layer can be controlled, and a separation layer that meets the deboronization conditions can be obtained to meet the boron removal requirements of the ultrapure water system.

[0037] Another innovative point of the present invention is the modified polysaccharide added to the amine solution. In addition to retaining the polyhydroxy structure, the modified polysaccharide has an additional amino structure, which can be embedded in the separation layer to provide good hydrophilicity; the modified polysaccharide has a certain volume, and the membrane pore size can be reduced by utilizing steric hindrance, and at the same time, it can provide specific adsorption of boron, and the prepared reverse osmosis membrane has a good boron removal rate. The key to the present invention lies in the selection of core components and the embedding method in the organic-organic interface. The components can be embedded quickly and stably without destroying the integrity of the separation layer, while improving the flux of the reverse osmosis membrane and maintaining a good desalination rate, thereby improving the boron removal rate of the reverse osmosis membrane.

[0038] Beneficial effects: Compared with the prior art, the present invention achieves the following significant effects:

[0039] (1) Compared with the preparation process of the traditional reverse osmosis membrane, the present invention adopts an organic-organic interface, and a dipole aprotic solvent promotes the dissolution of the amino-modified natural polyhydroxy polymer; a certain volume ratio of water is added to the dipole aprotic solvent to hinder the reverse diffusion rate of the acyl chloride monomer to a certain extent, and the nanobubbles generated by the reverse diffusion of the acyl chloride monomer help to increase the permeation flux of the separation layer; and the nanometer-scale particle size of the polymer in the solution is used to adjust the pore size generated by the nanobubbles, so as to achieve the regulation of the pore size inside the membrane, have more mesh pore structures, and improve the deboronization performance of the reverse osmosis membrane; therefore, the technical problem of the existing polyamide reverse osmosis membrane having a balance between the deboronization rate and the flux is solved;

[0040] (2) The amino-modified natural polyhydroxy polymer of the present invention has an amino group, which partially participates in interfacial polymerization at the organic-organic interface, regulates the polymerization reaction at the interface, and realizes the regulation of the membrane surface structure;

[0041] (3) The amino-modified natural polyhydroxy polymer embedded in the separation layer has polyhydroxy functional groups, which have a specific adsorption effect on boric acid, increase the resistance of boron passing through the membrane, and improve the removal effect of boron by the reverse osmosis membrane;

[0042] (4) The amino-modified natural polyhydroxy polymer embedded in the separation layer has amino functional groups, which can neutralize the acid formed by the complexation reaction between boric acid and hydroxyl groups without destroying the structure of the separation layer;

[0043] (5) The core component raw materials used in the present invention are natural polysaccharides, which have a wide range of sources, strong biocompatibility, and low modification difficulty. DETAILED DESCRIPTION

[0044] The present invention is described in further detail below.

[0045] Example 1

[0046] (1) dissolving aminoglucan in DMF, then adding and dissolving m-phenylenediamine, and then adding deionized water; controlling the mass fraction of aminoglucan in the formed solution to be 1wt%, the mass fraction of m-phenylenediamine to be 2wt%, and the volume percentage of water in the mixed solvent to be 40% (v / v). Immersing the polysulfone porous base membrane in the solution, taking out the base membrane after standing for 10 minutes, and removing the unbound aqueous monomers on the membrane surface by using an air knife;

[0047] (2) a n-hexane solution containing 0.15 wt% of trimesoyl chloride was evenly distributed on the surface of the membrane obtained in step (1), and the membrane was taken out after reacting for 1 min. It was found that no obvious gel appeared on the membrane surface;

[0048] (3) The membrane surface prepared in step (2) was cleaned with n-hexane for 30 seconds, and then dried at 80° C. for 2 minutes to obtain a reverse osmosis membrane with both flux and boron removal rate, which was stored in deionized water.

[0049] After the reverse osmosis membrane prepared in Example 1 was taken out, the membrane separation capacity was tested at 25°C and 2MPa using a high-pressure flat membrane device. The raw liquid 1 was a 2000ppm NaCl solution. The reverse osmosis membrane prepared in this example had a sodium chloride rejection rate of more than 98% and a flux of 30.3Lm -2 h -1 Raw material 2 is to add boric acid to raw material 1 to adjust the boron concentration to 5 mg / L. The boron concentration in the produced water is detected by ICP-OES analyzer, and the calculated boron removal rate can reach 91%.

[0050] Example 2

[0051] (1) dissolving aminocellulose in DMF, then adding m-phenylenediamine and dissolving it, and then adding deionized water; controlling the mass fraction of aminodextran in the formed solution to be 2wt%, the mass fraction of m-phenylenediamine to be 4wt%, and the volume percentage of water in the mixed solvent to be 50% (v / v). Immersing the polysulfone porous base membrane in the solution, taking out the base membrane after standing for 20 minutes, and removing the unbound aqueous monomers on the membrane surface by using an air knife;

[0052] (2) a n-hexane solution containing 0.4 wt% of trimesoyl chloride was evenly distributed on the surface of the membrane obtained in step (1), and the membrane was taken out after reacting for 2 minutes. It was found that no obvious gel appeared on the membrane surface;

[0053] (3) The membrane surface prepared in step (2) was cleaned with n-hexane for 60 seconds, and then dried at 100° C. for 3 minutes to obtain a reverse osmosis membrane with both flux and boron removal rate, which was stored in deionized water.

[0054] After the reverse osmosis membrane prepared in Example 2 was taken out, the membrane separation capacity was tested at 25°C and 2MPa using a high-pressure flat membrane device. The raw liquid 1 was a 2000ppm NaCl solution. The rejection rate of the reverse osmosis membrane prepared in this example for sodium chloride exceeded 98.3%, and the flux was 26.8Lm -2 h -1 Raw material 2 is to add boric acid to raw material 1 to adjust the boron concentration to 5 mg / L. The boron concentration in the produced water is detected by ICP-OES analyzer, and the calculated boron removal rate can reach 93%.

[0055] Example 3

[0056] (1) dissolving amino starch in DMF, then adding m-phenylenediamine and dissolving it, and then adding deionized water; controlling the mass fraction of aminoglucan in the formed solution to be 0.1wt%, the mass fraction of m-phenylenediamine to be 0.5wt%, and the volume percentage of water in the mixed solvent to be 20% (v / v). Immersing the polysulfone porous base membrane in the solution, taking out the base membrane after standing for 1 min, and removing the unbound aqueous monomers on the membrane surface by using an air knife;

[0057] (2) a n-hexane solution containing 0.1 wt% of trimesoyl chloride was evenly distributed on the surface of the membrane obtained in step (1), and the membrane was taken out after reacting for 30 seconds. It was found that no obvious gel appeared on the membrane surface;

[0058] (3) The membrane surface prepared in step (2) was cleaned with n-hexane for 10 seconds, and then dried at 60° C. for 1 minute to obtain a reverse osmosis membrane with both flux and boron removal rate, which was stored in deionized water.

[0059] After the reverse osmosis membrane prepared in Example 3 was taken out, the membrane separation capacity was tested at 25°C and 2MPa using a high-pressure flat membrane device. The raw liquid 1 was a 2000ppm NaCl solution. The rejection rate of the reverse osmosis membrane prepared in this example for sodium chloride exceeded 97.4%, and the flux was 34.9Lm -2 h -1 Raw material 2 is to add boric acid to raw material 1 to adjust the boron concentration to 5 mg / L. The boron concentration in the produced water is detected by ICP-OES analyzer, and the calculated boron removal rate can reach 86%.

[0060] Comparative Example 1

[0061] (1) dissolving aminoglucan in DMF, then adding and dissolving m-phenylenediamine; controlling the mass fraction of aminoglucan in the formed solution to be 1wt% and the mass fraction of m-phenylenediamine to be 2wt%. The polysulfone porous base membrane is immersed in the solution, and after standing for 10 minutes, the base membrane is taken out, and the unbound aqueous monomers on the membrane surface are removed by using an air knife;

[0062] (2) A n-hexane solution containing 0.15 wt% of trimesoyl chloride was uniformly distributed on the surface of the membrane obtained in step (1). However, after the interfacial polymerization reaction was completed, no obvious polyamide separation layer film structure could be observed on the membrane surface, and a reverse osmosis membrane could not be obtained.

[0063] This example mainly illustrates that TMC has a good diffusion coefficient in polar solvents and a pure organic-organic system is not conducive to the formation of a polyamide separation layer.

[0064] Comparative Example 2

[0065] (1) Dissolve m-phenylenediamine in DMF, and then add deionized water; control the mass fraction of m-phenylenediamine in the solution to be 2 wt%, and the volume percentage of water in the mixed solvent to be 40% (v / v). Immerse the polysulfone porous base membrane in the solution, let it stand for 10 minutes, then take out the base membrane, and use an air knife to remove the unbound aqueous monomers on the membrane surface;

[0066] (2) a n-hexane solution containing 0.15 wt% of trimesoyl chloride was evenly distributed on the surface of the membrane obtained in step (1), and the membrane was taken out after reacting for 1 min. It was found that no obvious gel appeared on the membrane surface;

[0067] (3) The membrane surface prepared in step (2) was cleaned with n-hexane for 30 seconds, then dried at 80° C. for 2 minutes, and stored in deionized water.

[0068] The membrane prepared in Comparative Example 2 is a blank control group. The membrane separation capacity test was carried out using a high-pressure flat membrane device at 25°C and 2MPa. The raw material liquid 1 was a 2000ppm NaCl solution. The reverse osmosis membrane prepared in this example had a sodium chloride rejection rate of 96.3% and a flux of only 18Lm -2 h -1 Raw material 2 is to add boric acid to raw material 1 to adjust the boron concentration to 5 mg / L. The boron concentration in the produced water is detected by ICP-OES analyzer, and the calculated boron removal rate is only 55%.

[0069] It can be seen that the flux and boron removal rate of the reverse osmosis membrane prepared based on this method have been significantly improved.

Claims

1. A high-flux high-boron removal reverse osmosis membrane, characterized in that: The preparation raw materials include solvent, solute and base membrane material; the solvent includes dipole aprotic solvent / water mixed solvent and n-hexane; the solute includes aromatic acyl chloride monomer, aromatic diamine monomer and amino-modified natural polyhydroxy polymer; the base membrane material is polysulfone ultrafiltration membrane.

2. The high-flux high-boron removal reverse osmosis membrane according to claim 1, characterized in that: The amino-modified natural polyhydroxy polymer is a polysaccharide amino-modified polymer, and the amino-modified natural polyhydroxy polymer has an amino group and a plurality of hydroxyl functional groups.

3. The high-flux high-boron removal reverse osmosis membrane according to claim 1, characterized in that: The amino-modified natural polyhydroxy polymer is at least one of aminodextran, aminocellulose or aminostarch.

4. The high-flux high-boron removal reverse osmosis membrane according to claim 1, characterized in that: The solvent for dissolving the aromatic acyl chloride monomer is n-hexane, and the mass fraction of the aromatic acyl chloride monomer in the n-hexane is 0.1-0.4 wt %.

5. The high-flux high-boron removal reverse osmosis membrane according to claim 1, characterized in that: The aromatic diamine monomer and the amino-modified natural polyhydroxy polymer are dissolved together in a dipolar aprotic solvent / water mixed solvent, wherein the mass fraction of the aromatic diamine monomer in the dipolar aprotic solvent / water mixed solvent is 0.5-4wt%, and the mass fraction of the amino-modified natural polyhydroxy polymer in the dipolar aprotic solvent / water mixed solvent is 0.1-2wt%.

6. The high-flux high-boron removal reverse osmosis membrane according to claim 1, characterized in that: The volume proportion of water in the dipolar aprotic solvent / water mixed solvent is 20-50%.

7. The high-flux high-boron removal reverse osmosis membrane according to claim 1, characterized in that: The dipolar aprotic solvent is at least one of dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide and N-methylpyrrolidone.

8. The high-flux high-boron removal reverse osmosis membrane according to claim 1, characterized in that: The aromatic diamine monomer is a phenylenediamine monomer, and the phenylenediamine monomer is at least one of o-phenylenediamine, m-phenylenediamine and p-phenylenediamine.

9. A method for preparing a high-flux high-boron removal reverse osmosis membrane according to claim 1, characterized in that: The following steps are involved: (1) dissolving an aromatic acyl chloride monomer in n-hexane to obtain a solution A; (2) dissolving the amino-modified natural polyhydroxy polymer in a dipolar aprotic solvent to obtain a solution B; (3) dissolving an aromatic diamine monomer into solution B, and then adding water to obtain solution C; (4) Immerse the basement membrane in solution C and let it stand; (5) After removing the residual solution C on the surface of the basement membrane, the basement membrane is immersed in solution A to allow interfacial polymerization to react for a period of time; (6) The membrane after the reaction is post-treated to obtain a reverse osmosis membrane.

10. The method for preparing a high-flux high-boron removal reverse osmosis membrane according to claim 9, characterized in that: The post-treatment step in step (6) is divided into two steps. The first step is to use n-hexane to clean the membrane surface for 10-60 seconds; the second step is heat treatment at a temperature of 60-100°C for 1-3 minutes.

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