Polyamide composite reverse osmosis membrane and preparation method thereof

Abstract

The invention relates to a polyamide composite reverse osmosis membrane and a preparation method thereof. The polyamide composite reverse osmosis membrane comprises a base membrane, the separation layer covers the base membrane and is prepared by carrying out interfacial polymerization reaction on a water phase solution and an oil phase solution; the separating layer is covered with the functional layer, the functional layer is a reaction product of end-capping reagents and carboxyl-terminated groups of the separating layer, and the end-capping reagents are respectively a single-functional-group end-capping reagent and a multi-functional-group modifier. The preparation method of the polyamide composite reverse osmosis membrane comprises the step of soaking the base membrane which is sequentially soaked in a water phase solution and an oil phase solution in a solution containing an end-capping reagent. According to the polyamide composite reverse osmosis membrane prepared by the preparation method provided by the invention, the surface carboxyl content is reduced, the surface potential is improved, and the adsorption of pollutants is reduced, so that the water efficiency and the desalination rate are improved.

Description

Technical Field

[0001] The invention relates to the field of reverse osmosis membrane manufacturing, and in particular to a polyamide composite reverse osmosis membrane and a preparation method thereof. Background Art

[0002] Reverse osmosis technology plays an important role in water treatment, such as desalination and sewage treatment. However, as the scope of application expands, the complexity of water quality increases, which makes it easy for pollutants to deposit on the membrane surface and form biofilms, affecting membrane performance and life. Positively charged substances in wastewater and sewage (such as surfactants, suspended solids, metal hydroxide colloidal particles and microbial metabolites) are easily adsorbed on traditional reverse osmosis membranes, causing membrane fouling, which not only reduces the water production and desalination rate of the system, but also increases the cleaning frequency and shortens the service life of the reverse osmosis membrane. Therefore, the ideal reverse osmosis membrane should not only have efficient desalination capacity, but also have good tolerance and anti-fouling properties.

[0003] At present, polyamide reverse osmosis membranes are mainly composed of a non-woven fabric layer, a porous support layer and a polyamide functional layer. There are many steps in the preparation of polyamide reverse osmosis membranes. First, the non-woven fabric and the porous support membrane form a base membrane, which first contacts the aqueous solution, and then is squeezed by a roller and a common air knife to remove excess aqueous solution. At this time, an aqueous monomer layer is formed on the surface of the base membrane, and then it is contacted with an oil phase solution. In this process, the aqueous monomer and the oil phase monomer on the surface of the base membrane are fully contacted to cause an interfacial polymerization reaction, and then a series of post-treatments such as drying are performed to obtain the final polyamide reverse osmosis membrane.

[0004] During the interfacial polymerization process, the aromatic amine compound in the aqueous solution and the acyl halide compound in the oil phase solution react on the base membrane to form a long-chain polyamide. If the polymerization reaction is incomplete or the reaction conditions are not precisely controlled, the end of the polymer chain may retain the original functional group. The acyl halide reacts with water to generate the corresponding carboxylic acid and hydrogen halide, so the terminal functional group of the acyl halide reacts to form a carboxyl group. Under neutral or slightly alkaline conditions, the carboxyl group exists in the form of a carboxylate ion with a negative charge, which causes the surface potential of the formed polyamide reverse osmosis membrane to decrease, and it is very easy to adsorb positively charged pollutants, causing membrane pollution, and reducing the water flux and desalination rate of the polyamide reverse osmosis membrane. Therefore, it is urgent to optimize the preparation method of the polyamide reverse osmosis membrane to improve the anti-pollution property of the membrane and thus improve the water flux and desalination rate. Summary of the invention

[0005] Based on this, the purpose of the present invention is to overcome the defects or shortcomings of the prior art and provide a polyamide composite reverse osmosis membrane and a preparation method thereof.

[0006] A method for preparing a polyamide composite reverse osmosis membrane comprises the following steps:

[0007] S1: first immersing the base membrane in an aqueous solution, and then contacting the base membrane with an oil solution, at which time the aqueous and oil monomers undergo interfacial polymerization on the surface of the base membrane to obtain an initial polyamide reverse osmosis membrane;

[0008] S2: soaking the obtained initial polyamide reverse osmosis membrane in a solution containing a capping agent to obtain a polyamide composite reverse osmosis membrane.

[0009] The end-capping agent is a single functional group end-capping agent, which includes any one or more of aliphatic amines such as methylamine, ethylamine, cyclohexylamine, hexamethylenediamine, and aromatic anilines such as m-phenylenediamine and o-phenylenediamine.

[0010] In addition, the end-capping agent is a multi-functional group modifier, including compounds containing amino and any one or several functional groups of quaternary ammonium group, aldehyde group, etc., and flavonoid compounds containing amino and any one or several functional groups of phenolic hydroxyl group, ortho-methoxy group, etc.

[0011] The aqueous phase solution is an aqueous solution of an aromatic amine compound having at least two functional groups; and the oil phase solution is an organic solution of an acyl halide compound having at least two functional groups.

[0012] Compared with the prior art, the present invention proposes a new method, which uses a single functional group capping agent to react with the amide terminal carboxyl group to reduce the surface carboxyl content, increase the surface Zeta potential, and thus reduce the adsorption of pollutants; further, multiple functional group modifiers are used for capping and modification, which can more significantly improve the anti-pollution property while increasing the Zeta potential of the membrane surface.

[0013] In addition, the present invention also provides a polyamide composite reverse osmosis membrane, comprising a base membrane; a separation layer, the separation layer is covered on the base membrane, and is prepared by an interfacial polymerization reaction between an aqueous phase solution and an oil phase solution; and a functional layer, the functional layer is covered on the separation layer, and is a reaction product of a capping agent and a terminal carboxyl group of the separation layer.

[0014] The end-capping agent is a single functional group end-capping agent, which includes any one or more of aliphatic amines such as methylamine, ethylamine, cyclohexylamine, hexamethylenediamine, and aromatic anilines such as m-phenylenediamine and o-phenylenediamine.

[0015] In addition, the end-capping agent is a multi-functional group modifier, including compounds containing amino and any one or several functional groups of quaternary ammonium group, aldehyde group, etc., and flavonoid compounds containing amino and any one or several functional groups of phenolic hydroxyl group, ortho-methoxy group, etc.

[0016] The aqueous phase solution is an aqueous solution of an aromatic amine compound having at least two functional groups; and the oil phase solution is an organic solution of an acyl halide compound having at least two functional groups.

[0017] The base film comprises a non-woven fabric and a porous support body, wherein the porous support body is covered on the non-woven fabric and is made of polysulfone.

[0018] Compared with the prior art, the present invention proposes a new composite reverse osmosis membrane, which has a lower surface carboxyl content and a higher surface potential, thereby reducing the adsorption of pollutants and improving water efficiency and desalination rate.

[0019] For better understanding and implementation, the present invention is described in detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a flow chart of the method of Examples 1-6 of the present invention;

[0021] Figure 2 This is a diagram showing the changes in membrane flux ratio during contaminated operation of Example 1 and Comparative Example 1. DETAILED DESCRIPTION

[0022] Amino groups can react with the terminal carboxyl groups on the polyamide reverse osmosis membrane to increase the surface Zeta potential of the polyamide reverse osmosis membrane and improve the anti-fouling performance of the membrane; at the same time, the introduction of functional groups can further improve the comprehensive performance of the membrane, for example, the quaternary ammonium group carries a positive charge, which can reduce the adsorption of negatively charged pollutants by the membrane, thereby reducing the pollution rate of the membrane and improving the anti-fouling performance of the membrane. At the same time, the quaternary amine group can increase the hydrophilicity of the membrane surface and improve the water flux of the membrane; the aldehyde group affects the pore structure and surface characteristics of the membrane surface, thereby improving the separation performance of the membrane, such as increasing the desalination rate; phenolic hydroxyl and methoxy are both hydrophilic functional groups, which can increase the hydrophilicity of the membrane surface and reduce the adsorption of oil droplets and organic matter in water, thereby improving the water flux and anti-fouling performance of the membrane. Therefore, the amino group is used to cap the terminal carboxyl group of the polyamide reverse osmosis membrane, reduce the surface carboxyl content, and increase the surface potential. Further, the use of compounds with amino groups and other functional groups to react chemically with the polyamide reverse osmosis membrane can have the function of modifying the membrane on the basis of improving the surface potential of the membrane.

[0023] Based on the above-mentioned preparation design ideas, a polyamide composite reverse osmosis membrane and a preparation method thereof of the present invention are described in detail below. Figure 1 The flow chart shown:

[0024] (I) Preparation of initial polyamide reverse osmosis membrane

[0025] The base membrane is immersed in the aqueous solution for full immersion, and then the excess aqueous solution on the surface of the base membrane is removed by roller treatment or air knife treatment. The base membrane with the aqueous solution evenly distributed is contacted with the oil solution, and this contact process can be carried out by double-sided immersion or single-sided coating. During the contact process, the aqueous phase and oil phase monomers undergo interfacial polymerization on the surface of the base membrane. Finally, the base membrane after the interfacial polymerization reaction is placed in an oven for drying, thereby obtaining an initial polyamide reverse osmosis membrane.

[0026] Specifically, the base film includes a non-woven fabric and a porous support, the porous support is obtained by forming a polymer material coating on the non-woven fabric, and the porous support can be made of a variety of polymer materials, including but not limited to polysulfone, polyethersulfone, polycarbonate, polyethylene oxide, polyimide, polyetherimide, polyetheretherketone, polypropylene, polymethylpentene, polymethyl chloride or polyvinylidene fluoride, etc. Preferably, in the embodiments of the present invention and the comparative examples, the polymer material is polysulfone.

[0027] Specifically, the aqueous phase solution is an aqueous solution of an aromatic amine compound having at least two functional groups; and the oil phase solution is an organic solution of an acyl halide compound having at least two functional groups.

[0028] Preferably, in the embodiments and comparative examples of the present invention, the aromatic amine compound having at least two functional groups is m-phenylenediamine; the acyl halide compound having at least two functional groups is trimesoyl chloride, wherein, in order to reasonably regulate the interfacial polymerization reaction rate of the aqueous phase monomer and the oil phase monomer, tributyl phosphate is additionally added to the oil phase solution as an additive in this comparative example 2 and embodiments 5 and 6.

[0029] (II) Surface end-capping treatment

[0030] The obtained initial polyamide reverse osmosis membrane is immersed in a blocking agent solution to obtain a polyamide composite reverse osmosis membrane.

[0031] Specifically, the end-capping agent is a single functional group end-capping agent, which includes any one or more of aliphatic amines such as methylamine, ethylamine, cyclohexylamine, hexamethylenediamine, and aromatic anilines such as m-phenylenediamine and o-phenylenediamine.

[0032] In addition, the end-capping agent is a multi-functional group modifier, including compounds containing amino and any one or several functional groups of quaternary ammonium group, aldehyde group, etc., and flavonoid compounds containing amino and any one or several functional groups of phenolic hydroxyl group, ortho-methoxy group, etc.

[0033] Preferably, in an embodiment of the present invention, the single functional group capping agent is selected from m-phenylenediamine and hexamethylenediamine, and the multiple functional group modifiers are selected from 2-amino-3,4',5-trihydroxy-3',7-dimethoxyflavonoid compounds.

[0034] Based on the above-mentioned polyamide composite reverse osmosis membrane and its preparation method, the present invention further carried out experimental operation and verification of various parameters, which will be described in detail below.

[0035] Comparative Example 1

[0036] This comparative example is a method for preparing an initial polyamide reverse osmosis membrane without subsequent surface end-capping treatment, specifically, comprising the following steps: completely immersing the base membrane in an aqueous solution containing 3wt% m-phenylenediamine for 1 min, then removing excess water phase on the surface of the base membrane by roller and air knife treatment, and then completely immersing it in an organic solution containing 0.15wt% trimesoyl chloride for 10 s to complete the interfacial polymerization reaction and obtain a polyamide reverse osmosis membrane.

[0037] Example 1

[0038] This embodiment uses a solution containing 5 wt % of m-phenylenediamine as the single functional group capping agent solution.

[0039] The preparation method is as follows:

[0040] S11: the base membrane is completely immersed in an aqueous solution containing 3 wt% of m-phenylenediamine for 1 min, and then the excess water phase on the surface of the base membrane is removed by roller and air knife treatment, and then the base membrane is completely immersed in an organic solution containing 0.15 wt% of trimesoyl chloride for 10 s to complete the first interfacial polymerization and obtain an initial polyamide reverse osmosis membrane;

[0041] S12: Soaking the prepared initial polyamide reverse osmosis membrane in a solution containing 5 wt% of m-phenylenediamine for 2 minutes to allow the membrane to fully contact the solution and undergo a chemical reaction, followed by rinsing with pure water for 1 minute to obtain a polyamide composite reverse osmosis membrane.

[0042] Example 2

[0043] This embodiment uses a solution containing 0.02 wt % of 2-amino-3,4',5-trihydroxy-3',7-dimethoxyflavonoid compound as the multi-functional group modifier solution.

[0044] The preparation method of this embodiment is basically the same as that of embodiment 1, except that in step S21, the solution in which the initial polyamide reverse osmosis membrane is immersed is different, specifically:

[0045] S22: The prepared initial polyamide reverse osmosis membrane is immersed in a solution containing 0.02wt% 2-amino-3,4',5-trihydroxy-3',7-dimethoxyflavonoid compound for 2 minutes to allow the membrane to fully contact the solution and undergo a chemical reaction, and then rinsed with pure water for 1 minute to obtain a polyamide composite reverse osmosis membrane.

[0046] Example 3

[0047] This embodiment uses a solution containing 0.5 wt % of 2-amino-3,4',5-trihydroxy-3',7-dimethoxyflavonoid compound as the multi-functional group modifier solution.

[0048] The preparation method of this embodiment is basically the same as that of embodiment 1, except that in step S21, the solution in which the initial polyamide reverse osmosis membrane is immersed is different, specifically:

[0049] S32: The prepared initial polyamide reverse osmosis membrane is immersed in a solution containing 0.5wt% 2-amino-3,4',5-trihydroxy-3',7-dimethoxyflavonoid compound for 2 minutes to allow the membrane to fully contact the solution and undergo a chemical reaction, and then rinsed with pure water for 1 minute to obtain a polyamide composite reverse osmosis membrane.

[0050] Example 4

[0051] This embodiment uses a solution containing 1 wt % of 2-amino-3,4',5-trihydroxy-3',7-dimethoxyflavone compound as the multi-functional group modifier solution.

[0052] The preparation method of this embodiment is basically the same as that of embodiment 1, except that in step S21, the solution in which the initial polyamide reverse osmosis membrane is immersed is different, specifically:

[0053] S42: The prepared initial polyamide reverse osmosis membrane is immersed in a solution containing 1wt% 2-amino-3,4',5-trihydroxy-3',7-dimethoxyflavonoid compound for 2 minutes to allow the membrane to fully contact the solution and undergo a chemical reaction, and then rinsed with pure water for 1 minute to obtain a polyamide composite reverse osmosis membrane.

[0054] Comparative Example 2

[0055] This comparative example is a method for preparing a polyamide reverse osmosis membrane without subsequent end-capping treatment, specifically, comprising the following steps: completely immersing the base membrane in a 2.5wt% m-phenylenediamine solution for 1 minute, then removing excess water phase on the surface of the base membrane by roller and air knife treatment, and then completely immersing it in an organic solution containing 0.12wt% trimesoyl chloride and 0.12wt% tributyl phosphate added as an additive for 10 seconds to complete the interfacial polymerization reaction and obtain a polyamide reverse osmosis membrane.

[0056] Example 5

[0057] This embodiment uses a solution containing 2 wt % of hexamethylenediamine as the multi-functional group modifier solution.

[0058] The preparation method is as follows:

[0059] S51: The base membrane is completely immersed in an aqueous solution containing 2.5 wt% of m-phenylenediamine for 1 min, and then the excess water phase on the surface of the base membrane is removed by roller pressing and air knife treatment, and then the base membrane is completely immersed in an organic solution containing 0.12 wt% of trimesoyl chloride and 0.12 wt% of tributyl phosphate added as an additive for 10 s to complete the first interfacial polymerization and obtain an initial polyamide reverse osmosis membrane;

[0060] S52: Soak the prepared initial polyamide reverse osmosis membrane in a solution containing 2 wt% hexamethylenediamine for 2 minutes to allow the membrane to fully contact the solution and undergo a chemical reaction, and then rinse with pure water for 1 minute to obtain a polyamide composite reverse osmosis membrane.

[0061] Example 6

[0062] This embodiment uses a solution containing 5 wt % of hexamethylenediamine as the multi-functional group modifier solution.

[0063] The preparation method of this embodiment is basically the same as that of embodiment 5, except that in step S21, the initial polyamide reverse osmosis membrane soaking solution prepared is different, specifically:

[0064] S62: Soak the prepared initial polyamide reverse osmosis membrane in a solution containing 5 wt% hexamethylenediamine for 2 minutes to allow the membrane to fully contact the solution and undergo a chemical reaction, and then rinse with pure water for 1 minute to obtain a polyamide composite reverse osmosis membrane.

[0065] Parameter statistics

[0066] Parameter statistics of Examples 1-6 and Comparative Examples 1 and 2 are shown in Table 1. At the same time, for the sake of simplicity and clarity, the structural formulas of the reagents used in the above examples are as follows: m-phenylenediamine (MPD), trimesoyl chloride (TMC), tributyl phosphate (TBP) and hexamethylenediamine (HMDA).

[0067] Table 1

[0068]

[0069] Test Method

[0070] The performance test and analysis were performed on the polyamide composite reverse osmosis membranes prepared in Examples 1 to 6 and the polyamide reverse osmosis membrane prepared in the comparative example. Specifically, the following are the performance parameters that need to be tested and their testing methods.

[0071] 1. Membrane surface potential

[0072] The Zeta potential of each membrane surface was detected using the GB / T 37617-2019 nanofiltration membrane surface Zeta potential test method.

[0073] 2. Desalination rate and water flux

[0074] Initial test conditions: test pressure is 0.4MPa; inlet water temperature is controlled at 25.0°C; feed liquid is an aqueous solution containing 250ppm sodium chloride.

[0075] Water efficiency water test conditions: This condition simulates the actual water treatment conditions, the pressure and temperature are the same as the test condition 1, and the feed liquid is different. Specifically, the feed liquid is an aqueous solution composed of 250ppm sodium chloride, 190ppm calcium chloride, 103ppm magnesium sulfate, and 255ppm sodium bicarbonate.

[0076] The water flux and desalination rate of the membrane element were tested and calculated under the initial performance test conditions and water efficiency and water performance test conditions respectively.

[0077] (1) The salt rejection rate indicates the ability of the membrane to remove soluble salts in water. The calculation formula is as follows:

[0078]

[0079] Among them, C p is the salt content of the permeate, in mg / L; C f It is the salt content of the feed liquid, in mg / L.

[0080] (2) Water flux refers to the amount of water that passes through a unit membrane area per unit time. The calculation formula is as follows:

[0081]

[0082] Where V is the volume of the permeate, in L; t is the running time, in h; S is the effective membrane area, in m 2 .

[0083] 3. Membrane specific flux

[0084] Membrane specific flux is used to describe the performance of reverse osmosis membrane under specific conditions, especially when considering the anti-fouling ability of reverse osmosis membrane. The calculation formula is as follows:

[0085]

[0086] Wherein, Q is the membrane flux during the fouling period, in LMH / MPa; J is the water flux of the membrane, in LMH; P is the operating pressure, in MPa.

[0087] 4. Anti-pollution performance

[0088] S1 membrane element was operated at constant flux under the test conditions of operating pressure of 225 psi, inlet water temperature controlled at 25°C, pH value maintained at 7.5±0.5, feed liquid being an aqueous solution containing 2000 ppm sodium chloride and 10 ppm aluminum chloride, and membrane recovery rate of 15%;

[0089] S2 When the membrane flux Q of the membrane element drops to 85% of the initial value, the membrane is cleaned by first using a 0.1% sodium hydroxide solution for pressure-free circulation cleaning, and then using a hydrochloric acid solution with a pH value of 2 for acid washing;

[0090] After S3 cleaning was completed, under the test conditions of an operating pressure of 1.0 MPa and a membrane recovery rate of 15%, an aqueous solution containing 2000 ppm sodium chloride was used to perform subsequent water flux and desalination rate testing and calculation on the membrane element to evaluate the cleaning effect and membrane recovery.

[0091] 5. Microbial contamination assessment

[0092] S1 was tested under the following test conditions: operating pressure of 1.0MPa, inlet water temperature controlled at 25℃, pH value maintained at 7.0±0.5, feed liquid containing 2000ppm sodium chloride aqueous solution, and membrane recovery rate of 15%, and the initial water flux J0 and desalination rate R0 of the membrane element were obtained;

[0093] S2 adds Escherichia coli culture solution (CFU=100 / mL) to the feed solution, runs for 12 hours, stops for 2 hours, and then continues to run for 2 hours. The water flux and desalination rate at this time are tested, and the number of bacteria is tested;

[0094] S3 was cleaned with an aqueous solution containing 0.1 wt% sodium hydroxide and then shut down for 1 hour to test the permeate flux J of the membrane element after cleaning. f and the salt rejection rate R f ;

[0095] S4 Based on the water flux calculated at different stages, the flux reduction rate after membrane element contamination and the flux recovery rate after cleaning are evaluated using the following specific formula.

[0096]

[0097] Test Results

[0098] 1. Characterization of Zeta potential of membrane surface in Examples 1, 5, 6 and Comparative Examples 1 and 2

[0099] Table 2

[0100]

[0101] Table 1 shows the surface Zeta potential of the initial polyamide reverse osmosis membrane and the polyamide composite reverse osmosis membrane. The results show that the surface potential of the polyamide composite reverse osmosis membrane is improved regardless of whether a single functional group capping agent is used for capping or multiple functional group modifiers are used for capping and modification.

[0102] 2. Calculation results of initial water flux and desalination rate of Examples 1-6 and Comparative Examples 1 and 2

[0103] Table 3

[0104]

[0105] The results shown in Table 2 indicate that the salt rejection rate of the polyamide composite reverse osmosis obtained is improved to a certain extent regardless of whether a single functional group capping agent is used for capping or multiple functional group modifiers are used for capping and modification.

[0106] 3. Water flux and desalination rate under initial and water-efficient water test conditions of Example 5 and Comparative Example 2

[0107] Table 4

[0108]

[0109] As shown in Table 3, the polyamide composite reverse osmosis membrane that is carboxyl terminated with hexamethylenediamine in a single functional group capping agent has a higher water efficiency water desalination rate, which is due to the increased membrane surface potential.

[0110] 4. Changes in membrane flux during fouling operation of Example 1 and Comparative Example 1

[0111] like Figure 2 As shown, the membrane specific flux attenuation rates of both membranes show a downward trend, and the membrane attenuation rate of Example 1 is slower than that of the membrane of Comparative Example 1, which indicates that the polyamide composite reverse osmosis membrane has a higher flux recovery rate.

[0112] 5. Pollution evaluation results of Examples 1, 3 and Comparative Example 1

[0113] Table 5

[0114]

[0115] Combining Table 1 and Table 4, it can be seen that the use of m-phenylenediamine to carboxyl-terminate the polyamide separation layer improves the Zeta potential of the membrane surface, and the use of 2-amino-3,4',5-trihydroxy-3',7-dimethoxyflavone compound to carboxyl-terminate the polyamide separation layer and introduce functional groups can obtain a composite reverse osmosis membrane with both improved membrane surface Zeta potential and improved anti-fouling properties.

[0116] The above data show that: the present invention uses a single functional group capping agent to perform carboxyl capping on the polyamide separation layer, while maintaining or improving the original water flux and desalination rate, the Zeta potential of the membrane surface is improved, the adsorption of positively charged pollutants is reduced, and the anti-pollution ability of the membrane is improved; further, multiple functional group modifiers are used to perform carboxyl capping and modification on the polyamide separation layer, which not only improves the Zeta potential of the membrane surface, but also significantly improves its anti-pollution ability, which will reduce the frequency of membrane cleaning and improve the efficiency of water treatment.

[0117] The present invention is not limited to the above-mentioned embodiments. If various changes or modifications to the present invention do not depart from the spirit and scope of the present invention, and if these changes and modifications fall within the scope of the claims and equivalent technologies of the present invention, the present invention is also intended to include these changes and modifications.

Claims

1. A method for preparing a polyamide composite reverse osmosis membrane, characterized in that: The base membrane soaked in the aqueous solution and the oily solution in sequence is soaked in a solution containing a capping agent to obtain a polyamide composite reverse osmosis membrane.

2. The method for preparing a polyamide composite reverse osmosis membrane according to claim 1, wherein: The end-capping agent is a single functional group end-capping agent, which includes any one or more of aliphatic amines such as methylamine, ethylamine, cyclohexylamine, hexamethylenediamine, and aromatic anilines such as m-phenylenediamine and o-phenylenediamine.

3. The method for preparing a polyamide composite reverse osmosis membrane according to claim 1, wherein: The end-capping agent is a multi-functional group modifier, including compounds containing amino, quaternary ammonium, aldehyde, etc., and flavonoid compounds containing amino, phenolic hydroxyl, ortho-methoxy, etc., or several functional groups.

4. The method for preparing a polyamide composite reverse osmosis membrane according to claims 2 and 3, characterized in that: The aqueous phase solution is an aqueous solution of an aromatic amine compound having at least two functional groups; and the oil phase solution is an organic solution of an acyl halide compound having at least two functional groups.

5. A polyamide composite reverse osmosis membrane, characterized in that: include: Basement membrane; A separation layer, which covers the base film and is prepared by interfacial polymerization of an aqueous solution and an oily solution; The functional layer covers the separation layer and is a reaction product of the end-capping agent and the terminal carboxyl group of the separation layer.

6. The polyamide composite reverse osmosis membrane according to claim 5, characterized in that: The end-capping agent is a single functional group end-capping agent, which includes any one or more of aliphatic amines such as methylamine, ethylamine, cyclohexylamine, hexamethylenediamine, and aromatic anilines such as m-phenylenediamine and o-phenylenediamine.

7. The polyamide composite reverse osmosis membrane according to claim 5, characterized in that: The end-capping agent is a multi-functional group modifier, including compounds containing amino, quaternary ammonium, aldehyde, etc., and flavonoid compounds containing amino, phenolic hydroxyl, ortho-methoxy, etc., or several functional groups.

8. The polyamide composite reverse osmosis membrane according to claim 6 or 7, characterized in that: The aqueous phase solution is an aqueous solution of an aromatic amine compound having at least two functional groups; and the oil phase solution is an organic solution of an acyl halide compound having at least two functional groups.

9. The polyamide composite reverse osmosis membrane according to claim 8, characterized in that: The base film comprises a non-woven fabric and a porous support body, wherein the porous support body is covered on the non-woven fabric and is made of polysulfone.

10. The polyamide composite reverse osmosis membrane according to any one of claims 5 to 9, which is made into a reverse osmosis membrane element and used in water treatment.

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