A composite reverse osmosis membrane and preparation method thereof

Abstract

The present invention relates to the field of water treatment technology, and in particular to a composite reverse osmosis membrane and a preparation method thereof. The preparation method comprises: A) pouring an aqueous phase solution from a corner of a base membrane fixed in the middle of a double-layer frame, so that the aqueous phase solution evenly and completely covers the surface of the base membrane, and then pouring out the excess aqueous phase solution; B) pouring an oil phase solution uniformly into the base membrane treated in step B) for reaction, pouring out the excess oil phase solution, and drying; C) soaking the composite membrane obtained in step B) in a modifier solution to obtain a composite reverse osmosis membrane; the modifier is selected from at least one of 4-amino-N-(5-chloro-2-quinoxaline) benzenesulfonamide and p-carboxylbenzenesulfonamide. The preparation method provided by the present invention improves the flux of the membrane while solving the problem of easy contamination of polyamide membranes.

Description

Technical Field

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

[0002] Membrane technology has been widely used in seawater desalination and sewage treatment. In recent years, reverse osmosis membranes represented by polyamide have been widely favored due to their excellent performance. However, membrane fouling has always been an important factor hindering its development. Therefore, it is particularly important to develop a reverse osmosis membrane that is resistant to fouling.

[0003] The separation mechanism of reverse osmosis membrane mainly includes: dissolution-diffusion model, hydrogen bond theory, etc. The generation of membrane fouling mainly includes the following two situations: (1) deposition and adsorption of substances with different physical and chemical properties; (2) chemical reaction with the membrane surface during the filtration process. If membrane fouling is not controlled, it will lead to reduced separation efficiency and increased energy consumption.

[0004] At present, the main mechanisms to prevent membrane fouling are: fouling removal mechanism, anti-fouling mechanism, contact anti-fouling mechanism, and release anti-fouling mechanism. The current polyamide reverse osmosis membrane modification methods include: post-membrane molding adjustment, surface coating, surface grafting, bionic bonding, in-situ adjustment, etc.

[0005] However, there are often many impurities in the aqueous phase of the existing synthesis process, which are accumulated on the surface of the membrane under the hydrophobic effect and electrostatic interaction, thereby causing membrane pollution and reducing membrane performance. Furthermore, while the existing technology improves the anti-fouling ability, it also reduces the flux of the membrane, thereby reducing the performance of the membrane. Summary of the invention

[0006] In view of this, the technical problem to be solved by the present invention is to provide a composite reverse osmosis membrane and a preparation method thereof, which can improve the flux of the membrane while solving the problem that the polyamide membrane is easy to be contaminated.

[0007] The present invention provides a method for preparing a composite reverse osmosis membrane, comprising the following steps:

[0008] A) pouring the aqueous solution from one corner of the base film fixed in the middle of the double-layer frame, so that the aqueous solution evenly and completely covers the surface of the base film, and then pouring out the excess aqueous solution;

[0009] B) pouring the oil phase solution uniformly onto the base film treated in step B) to react, pouring out the excess oil phase solution, and drying;

[0010] C) immersing the composite membrane obtained in step B) into a modifier solution to obtain a composite reverse osmosis membrane;

[0011] The modifier is selected from at least one of 4-amino-N-(5-chloro-2-quinoxaline)benzenesulfonamide and p-carboxybenzenesulfonamide.

[0012] Preferably, in step C), the mass concentration of the modifier solution is 0.3% to 0.8%.

[0013] Preferably, in step C), the soaking temperature is 50-60° C. and the soaking time is 3-8 min.

[0014] Preferably, in step A), the aqueous phase solution is composed of a multifunctional amine monomer, a surfactant, a polar organic solvent and water;

[0015] In the aqueous phase solution, the mass content of the multifunctional amine monomer is 0.5% to 5%, the mass content of the surfactant is 0.05% to 2%, and the mass content of the polar organic solvent is 3% to 10%.

[0016] Preferably, the multifunctional amine monomer is sulfonylsulfonamide, m-phenylenediamine, dicyclohexylamine or nicotinamide; the surfactant is 2-dodecylbenzenesulfonate, sodium dodecyl sulfate, dodecylbenzenesulfonic acid or boric acid alkyl alcohol amide; the polar organic solvent is isopropanol, acetonitrile, dimethyl sulfoxide or N,N-dimethylformamide.

[0017] Preferably, in step A), the basement membrane comprises:

[0018] substrate;

[0019] A coating layer formed on a surface of a substrate;

[0020] The coating layer is prepared from raw materials including N,N-dimethylformamide and sulfonated polysulfone.

[0021] Preferably, in step B), the oil phase solution consists of a multifunctional acyl halide and an oil phase solvent;

[0022] In the oil phase solution, the mass content of the multifunctional acyl halide is 0.05% to 0.3%.

[0023] Preferably, the multifunctional acyl halide is trimesoyl chloride, monomethyl adipate chloride, thiopheneacetyl chloride or diphenylacetyl chloride;

[0024] The oil phase solvent is selected from at least one of n-hexane, Isopar G and Isopar L.

[0025] Preferably, in step B), the reaction temperature is 50-65°C and the reaction time is 0.2-0.6 h;

[0026] After the drying, the method further comprises: rinsing with n-hexane;

[0027] The rinsing temperature is 20-25°C and the rinsing time is 4-8 s.

[0028] The present invention also provides a composite reverse osmosis membrane prepared by the preparation method described above.

[0029] The present invention provides a method for preparing a composite reverse osmosis membrane, comprising the following steps: A) pouring an aqueous phase solution from a corner of a base membrane fixed in the middle of a double-layer frame, so that the aqueous phase solution evenly and completely covers the surface of the base membrane, and then pouring out the excess aqueous phase solution; B) pouring an oil phase solution uniformly onto the base membrane treated in step B) for reaction, and then pouring out the excess oil phase solution and drying; C) soaking the composite membrane obtained in step B) in a modifier solution to obtain a composite reverse osmosis membrane; the modifier is selected from at least one of 4-amino-N-(5-chloro-2-quinoxaline)benzenesulfonamide and p-carboxylbenzenesulfonamide. In the present invention, a specific sulfonamide group is grafted onto a polyamide layer as a carrier, and has good hydrophilicity. The specific sulfonamide group not only improves the anti-fouling ability of the polyamide membrane, but also improves the membrane flux, and has a higher desalination rate. In addition, the sulfonamide group reacts with the acyl chloride group and is covalently bonded to the surface of the polyamide layer, which greatly improves its stability. At the same time, the preparation method provided by the present invention is simple to operate and takes a short time. DETAILED DESCRIPTION

[0030] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] The present invention provides a method for preparing a composite reverse osmosis membrane, comprising the following steps:

[0032] A) pouring the aqueous solution from one corner of the base film fixed in the middle of the double-layer frame, so that the aqueous solution evenly and completely covers the surface of the base film, and then pouring out the excess aqueous solution;

[0033] B) pouring the oil phase solution uniformly onto the base film treated in step B) to react, pouring out the excess oil phase solution, and drying;

[0034] C) immersing the composite membrane obtained in step B) into a modifier solution to obtain a composite reverse osmosis membrane;

[0035] The modifier is selected from at least one of 4-amino-N-(5-chloro-2-quinoxaline)benzenesulfonamide and p-carboxybenzenesulfonamide.

[0036] Regarding step A):

[0037] The aqueous phase solution is poured from one corner of the base film fixed in the middle of the double-layer frame, so that the aqueous phase solution evenly and completely covers the surface of the base film, and then the excess aqueous phase solution is poured out.

[0038] In some embodiments of the present invention, the basement membrane comprises:

[0039] substrate;

[0040] A coating layer formed on a surface of a substrate;

[0041] The coating layer is prepared from raw materials including N,N-dimethylformamide and sulfonated polysulfone.

[0042] The substrate is non-woven fabric.

[0043] The mass ratio of the N,N-dimethylformamide to the sulfonated polysulfone is 80-90:10-20, such as 86:14.

[0044] In some embodiments of the present invention, the basement membrane fixed in the middle of the double-layer frame is prepared according to the following method:

[0045] The substrate is fixed vertically in the middle of the double-layer frame, and the casting liquid is poured from one corner of the substrate so that the casting liquid evenly and completely covers the surface of the substrate, and then the excess casting liquid is poured out to obtain a base film fixed in the middle of the double-layer frame.

[0046] The double-layer frame is made of acrylic.

[0047] In the present invention, the substrate can be cut to fit the size of the double-layer frame, and then the cut substrate is fixed in the middle of the double-layer frame.

[0048] The casting solution comprises N,N-dimethylformamide and sulfonated polysulfone; the mass ratio of the N,N-dimethylformamide to the sulfonated polysulfone is 80-90:10-20, such as 86:14.

[0049] The casting solution can be obtained by mixing N,N-dimethylformamide and sulfonated polysulfone; the mixing is stirring; the mixing temperature is 65-75° C., such as 70° C.; and the mixing time is 3-5 h, such as 4 h.

[0050] The casting solution is poured in at a rate of 10-12 L / h, such as 12 L / h.

[0051] After pouring out the excess casting liquid, the method further includes: soaking in water for a period of time and drying. Phase transformation occurs after soaking in water, and the film is solidified, and the residual casting liquid can be washed away at the same time. The water is deionized water. The soaking time is 3 to 5 minutes, such as 5 minutes.

[0052] The present invention pours the aqueous solution from one corner of the base film fixed in the middle of the double-layer frame, so that the aqueous solution evenly and completely covers the surface of the base film, and then pours out the excess aqueous solution.

[0053] In some embodiments of the present invention, the aqueous phase solution is composed of a multifunctional amine monomer, a surfactant, a polar organic solvent and water. In the aqueous phase solution, the mass content of the multifunctional amine monomer is 0.5% to 5%, the mass content of the surfactant is 0.05% to 2%, and the mass content of the polar organic solvent is 3% to 10%. The multifunctional amine monomer is sulfonyl sulfonamide, m-phenylenediamine, dicyclohexylamine or nicotinamide; the surfactant is 2-dodecylbenzene sulfonate, sodium dodecyl sulfate, dodecylbenzene sulfonic acid or boric acid alkyl alcohol amide; the polar organic solvent is isopropanol, acetonitrile, dimethyl sulfoxide or N,N-dimethylformamide.

[0054] In some embodiments of the present invention, the rate of pouring the aqueous solution is 8 to 15 L / h, such as 15 L / h.

[0055] In some embodiments of the present invention, one corner of the base film may be the upper right corner or the upper left corner.

[0056] Regarding step B):

[0057] The oil phase solution is uniformly poured onto the base film treated in step B) to react, and then the excess oil phase solution is poured out and dried.

[0058] In some embodiments of the present invention, the oil phase solution is composed of a multifunctional acyl halide and an oil phase solvent. In the oil phase solution, the mass content of the multifunctional acyl halide is 0.05% to 0.3%. The multifunctional acyl halide is trimesoyl chloride, adipic acid monomethyl ester chloride, thiophene acetyl chloride or diphenylacetyl chloride.

[0059] In some embodiments of the present invention, the oil phase solvent is selected from at least one of n-hexane, Isopar G and Isopar L.

[0060] In some embodiments of the present invention, the pouring rate of the oil phase solution is 12-20 L / h, such as 20 L / h. The oil phase solution is poured at a uniform speed from one corner of the base film treated in step B), so that the oil phase solution evenly and completely covers the surface of the base film treated in step B). The one corner of the base film can be the upper right corner or the upper left corner.

[0061] In some embodiments of the present invention, the reaction temperature is 50-65° C., such as 60° C., and the reaction time is 0.2-0.6 h, such as 0.4 h.

[0062] In some embodiments of the present invention, the drying temperature is 55-65° C., such as 60° C., and the drying time is 5-15 min, such as 10 min. The drying is performed in an air drying oven.

[0063] In some embodiments of the present invention, after drying, the method further comprises: rinsing with n-hexane. Specifically, the method comprises:

[0064] Pour n-hexane onto the dried composite membrane for rinsing. After rinsing, pour out the n-hexane and dry.

[0065] Rinse with n-hexane to remove the residual polyamide layer before curing and optimize the membrane structure.

[0066] The rinsing temperature is 20-25° C., such as 25° C., and the rinsing time is 4-8 s, such as 6 s.

[0067] In some embodiments of the present invention, the drying temperature is 55-65° C., such as 60° C., and the drying time is 5-15 min, such as 10 min. The drying is performed in an air drying oven.

[0068] Regarding step C):

[0069] The composite membrane obtained in step B) is immersed in a modifier solution to obtain a composite reverse osmosis membrane.

[0070] The modifier solution consists of a modifier and a solvent. The modifier solution does not contain 2-(2,3-epoxypropylthio)thiophene and diglycidyl ether.

[0071] The modifier is selected from at least one of 4-amino-N-(5-chloro-2-quinoxaline)benzenesulfonamide and p-carboxybenzenesulfonamide.

[0072] In some embodiments of the present invention, the mass concentration of the modifier solution is 0.3% to 0.8%, such as 0.5%. The solvent of the modifier solution is one or more of water, acetonitrile, isopropanol, methanol and dimethyl sulfoxide.

[0073] In some embodiments of the present invention, the immersion temperature is 50-60° C., such as 55° C., and the immersion time is 3-8 min, such as 5 min.

[0074] The present invention also provides a composite reverse osmosis membrane prepared by the preparation method described above. The composite reverse osmosis membrane comprises:

[0075] Basement membrane;

[0076] a polyamide layer formed on the surface of the base film;

[0077] a sulfonamide monomer layer formed on the surface of the polyamide layer;

[0078] The component of the sulfonamide monomer layer is selected from at least one of 4-amino-N-(5-chloro-2-quinoxaline)benzenesulfonamide and p-carboxybenzenesulfonamide.

[0079] The modification process of the invention is simple and saves time.

[0080] The present invention has no particular limitation on the sources of the raw materials used above, and they can be generally commercially available.

[0081] In order to further illustrate the present invention, a composite reverse osmosis membrane and a preparation method thereof provided by the present invention are described in detail below in conjunction with embodiments, but it should not be construed as limiting the scope of protection of the present invention.

[0082] In the embodiments and comparative examples,

[0083] Preparation of casting solution: Take 86 parts by mass of N,N-dimethylformamide and 14 parts by mass of sulfonated polysulfone (BASF, Germany, S2010G6), stir at high speed at 70°C for 4 hours to obtain a uniform transparent solution.

[0084] Example 1

[0085] 1) Cut the non-woven fabric to fit the size of the acrylic frame, and fix the cut non-woven fabric (15cm×15cm) vertically between the two acrylic frames;

[0086] Measure 30 mL of casting solution and slowly pour it from the upper right corner of the non-woven fabric (12L / h) until the casting solution evenly and completely covers the surface of the non-woven fabric, and then pour the excess casting solution into a waste container. Soak the non-woven fabric coated with the casting solution in a container filled with deionized water for 5 minutes to solidify into a film to obtain a base film.

[0087] 2) The aqueous phase solution is a multifunctional amine monomer (sulfonyl sulfonamide), a surfactant (2-dodecylbenzene sulfonate), a polar organic solvent (isopropanol) and water; in the aqueous phase solution, the mass content of the multifunctional amine monomer is 2%, the mass content of the surfactant is 1%, and the mass content of the polar organic solvent is 6%.

[0088] Measure 30 mL of the aqueous solution and slowly pour it from the upper right corner of the basement membrane (15 L / h) until the aqueous solution evenly and completely covers the surface of the basement membrane. Pour out the excess aqueous solution into a container for later use.

[0089] 3) The oil phase solution is a multifunctional acyl halide (trimethylenediamine chloride) and an oil phase solvent (n-hexane); the mass content of the multifunctional acyl halide in the oil phase solution is 0.15%.

[0090] 30 mL of the oil phase solution was measured and poured uniformly (20 L / h) from one corner of the base film treated in step 2). After reacting at 60°C for 0.4 h, the excess oil phase solution was poured out and kept in an air drying oven at 60°C for 10 min. N-hexane was poured onto the dried composite membrane, and after rinsing at 25°C for 6 s, the n-hexane was poured out and kept in an air drying oven at 60°C for 10 min.

[0091] 4) The modifier is 4-amino-N-(5-chloro-2-quinoxaline)benzenesulfonamide, and the solvent of the modifier solution is dimethyl sulfoxide; the mass concentration of the modifier solution is 0.5%.

[0092] The composite membrane obtained in step 3) is immersed in a 55° C. modifier solution for 5 min to obtain a composite reverse osmosis membrane.

[0093] Example 2

[0094] The difference from Example 1 is:

[0095] In step 4), the modifier is p-carboxybenzenesulfonamide.

[0096] The remaining steps and parameters are the same as those in Example 1 to obtain a composite reverse osmosis membrane.

[0097] Example 3

[0098] The difference from Example 1 is:

[0099] In step 4), the mass concentration of the modifier solution is 0.4%.

[0100] The remaining steps and parameters are the same as those in Example 1 to obtain a composite reverse osmosis membrane.

[0101] Example 4

[0102] The difference from Example 1 is:

[0103] In step 4), the mass concentration of the modifier solution is 0.6%.

[0104] The remaining steps and parameters are the same as those in Example 1 to obtain a composite reverse osmosis membrane.

[0105] Comparative Example 1

[0106] The difference from Example 1 is:

[0107] In step 4), the modifier is 3,4-dimethoxybenzenesulfonamide.

[0108] The remaining steps and parameters are the same as those in Example 1 to obtain a composite reverse osmosis membrane.

[0109] Comparative Example 2

[0110] The difference from Example 1 is:

[0111] In step 4), the modifier is 4-butylbenzenesulfonamide.

[0112] The remaining steps and parameters are the same as those in Example 1 to obtain a composite reverse osmosis membrane.

[0113] Comparative Example 3

[0114] The difference from Example 1 is:

[0115] In step 4), the modifier is N,N-dimethyl-4-iodobenzenesulfonamide.

[0116] The remaining steps and parameters are the same as those in Example 1 to obtain a composite reverse osmosis membrane.

[0117] Comparative Example 4

[0118] The difference from Example 1 is:

[0119] In step 4), the modifier is 4-(2-formyl-1H-pyrrol-1-yl)benzenesulfonamide.

[0120] The remaining steps and parameters are the same as those in Example 1 to obtain a composite reverse osmosis membrane.

[0121] Comparative Example 5

[0122] The difference from Example 1 is:

[0123] In step 4), the modifier is 3,4-diamino-n-(3-trifluoromethyl-phenyl)-benzenesulfonamide.

[0124] The remaining steps and parameters are the same as those in Example 1 to obtain a composite reverse osmosis membrane.

[0125] Comparative Example 6

[0126] The difference from Example 1 is:

[0127] In step 4), the modifier is 3-aminobenzenesulfonamide.

[0128] The remaining steps and parameters are the same as those in Example 1 to obtain a composite reverse osmosis membrane.

[0129] Comparative Example 7

[0130] The difference from Example 1 is:

[0131] Step 2) is:

[0132] The aqueous phase solution is a multifunctional amine monomer (sulfonyl sulfonamide), a surfactant (2-dodecylbenzene sulfonate), a polar organic solvent (isopropanol) and water; in the aqueous phase solution, the mass content of the multifunctional amine monomer is 2%, the mass content of the surfactant is 1%, and the mass content of the polar organic solvent is 6%.

[0133] Measure 30 mL of the aqueous solution and pour it directly on the surface of the basement membrane. Use an air gun to spread it until it completely covers the surface of the basement membrane.

[0134] The remaining steps and parameters are the same as those in Example 1 to obtain a composite reverse osmosis membrane.

[0135] Comparative Example 8

[0136] The difference from Example 1 is:

[0137] Step 4) is:

[0138] Prepare an ethanol solution of 0.1 wt% 2-(2,3-epoxypropylthio)thiophene and 0.1 wt% polyethylene glycol diglycidyl ether, stir at room temperature for 2 h until uniform, to obtain solution A; then prepare an ethanol solution of 0.3 wt% 3,4-diamino-n-(3-trifluoromethyl-phenyl)-benzenesulfonamide, stir at room temperature for 2 h until uniform, to obtain solution B; mix solution A and solution B in a mass ratio of 1:1 to obtain a mixed solution; soak the composite membrane obtained in step 3) in the mixed solution for 5 min to obtain a composite reverse osmosis membrane.

[0139] Diaphragm performance evaluation:

[0140] The composite reverse osmosis membranes obtained in the above examples and comparative examples were tested for performance on a standard membrane test bench:

[0141] The calculation formula of flux F is shown in formula (1):

[0142] Formula (1);

[0143] In formula (1), V is the volume of permeate, gallons;

[0144] S is the effective membrane area, square feet ft;

[0145] t is time, h.

[0146] The calculation formula of desalination rate R is shown in formula (2):

[0147] Formula (2);

[0148] In formula (2), C f is the NaCl concentration in the stock solution, ppm;

[0149] C p is the NaCl concentration in the permeate, ppm.

[0150] Specific:

[0151] The test was conducted with a 2000 mg / L NaCl aqueous solution at 15.5 bar pressure, pH = 7.5, and 25 ± 0.4 °C. The results are shown in Table 1.

[0152] Table 1 Performance test results of composite reverse osmosis membrane

[0153]

[0154] The test was conducted with a 2000 mg / L NaCl aqueous solution at 15.5 bar pressure, pH = 4, and 25 ± 0.4 °C. The results are shown in Table 2.

[0155] Table 2 Performance test results of composite reverse osmosis membrane

[0156]

[0157] From the above experiments, it can be concluded that the performance of the membrane after soaking in the specific sulfonamide modifier solution is significantly improved. Examples 1, 3, and 4 prove that the optimal concentration of the modifying solution is 0.5 wt%.

[0158] Evaluation of antifouling ability: Tested with 2000 mg / L NaCl aqueous solution and 400 mg / L pollutant aqueous solution (bovine serum albumin, humic acid, etc.) at 15.5 bar pressure and 25±0.4℃:

[0159] First, the flux was measured under the condition of 1h 2000 mg / L NaCl aqueous solution as the test solution, which is recorded as J 0 ; Then the pollutant was added to a 2000 mg / L NaCl aqueous solution; the concentration of the pollutant in the NaCl aqueous solution was 400 mg / L, and the flux was measured for 8 hours under this test solution condition, recorded as J t ; Then wash with RO water for 15min 3 times, test its recovery flux, recorded as J wc .

[0160] Calculate the permeability decline rate FRD of the sewage solution after continuous filtration, as shown in formula (3);

[0161] Formula (3);

[0162] Calculate the corresponding permeate recovery rate PRR after physical washing, as shown in formula (4);

[0163] Formula (4).

[0164] The FRD and PPR of the composite reverse osmosis membranes of the embodiments and comparative examples are shown in Table 3.

[0165] Table 3 FRD and PPR of composite reverse osmosis membrane

[0166]

[0167] As can be seen from Table 3, as pollutants gradually accumulate, the transport resistance of the leachate gradually increases. The permeation decline rate of the embodiment is lower than that of the comparative example, indicating that the specific sulfonamide group can effectively reduce the adsorption and accumulation of pollutants on the polyamide layer. The recovery rate of Example 1 after physical water washing is the largest, indicating that the membrane recovery rate after being soaked in a specific sulfonamide reagent has increased.

[0168] The description of the above embodiments is only used to help understand the method of the present invention and its core idea. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a composite reverse osmosis membrane, characterized in that: The following steps are involved: A) pouring the aqueous solution from one corner of the base film fixed in the middle of the double-layer frame, so that the aqueous solution evenly and completely covers the surface of the base film, and then pouring out the excess aqueous solution; B) pouring the oil phase solution uniformly onto the base film treated in step B) to react, pouring out the excess oil phase solution, and drying; C) immersing the composite membrane obtained in step B) into a modifier solution to obtain a composite reverse osmosis membrane; The modifier solution consists of a modifier and a solvent; the modifier is selected from at least one of 4-amino-N-(5-chloro-2-quinoxaline)benzenesulfonamide and p-carboxylbenzenesulfonamide; and the solvent is one or more of water, acetonitrile, isopropanol, methanol and dimethyl sulfoxide.

2. The preparation method according to claim 1, characterized in that: In step C), the mass concentration of the modifier solution is 0.3% to 0.8%.

3. The preparation method according to claim 1, characterized in that: In step C), the soaking temperature is 50-60° C. and the soaking time is 3-8 min.

4. The preparation method according to claim 1, characterized in that: In step A), the aqueous phase solution is composed of a multifunctional amine monomer, a surfactant, a polar organic solvent and water; In the aqueous phase solution, the mass content of the multifunctional amine monomer is 0.5% to 5%, the mass content of the surfactant is 0.05% to 2%, and the mass content of the polar organic solvent is 3% to 10%.

5. The preparation method according to claim 4, characterized in that: The multifunctional amine monomer is sulfonylsulfonamide, m-phenylenediamine, dicyclohexylamine or nicotinamide; the surfactant is 2-dodecylbenzenesulfonate, sodium dodecyl sulfate, dodecylbenzenesulfonic acid or boric acid alkyl alcohol amide; the polar organic solvent is isopropanol, acetonitrile, dimethyl sulfoxide or N,N-dimethylformamide.

6. The preparation method according to claim 1, characterized in that: In step A), the base film comprises: substrate; A coating layer formed on a surface of a substrate; The coating layer is prepared from raw materials including N,N-dimethylformamide and sulfonated polysulfone.

7. The preparation method according to claim 1, characterized in that: In step B), the oil phase solution is composed of a multifunctional acyl halide and an oil phase solvent; In the oil phase solution, the mass content of the multifunctional acyl halide is 0.05% to 0.3%.

8. The preparation method according to claim 7, characterized in that: The multifunctional acyl halide is trimesoyl chloride, monomethyl adipate chloride, thiopheneacetyl chloride or diphenylacetyl chloride; The oil phase solvent is selected from at least one of n-hexane, Isopar G and Isopar L.

9. The preparation method according to claim 1, characterized in that: In step B), the reaction temperature is 50-65°C and the reaction time is 0.2-0.6 h; After the drying, the method further comprises: rinsing with n-hexane; The rinsing temperature is 20-25°C and the rinsing time is 4-8 s.

10. The composite reverse osmosis membrane obtained by the preparation method according to any one of claims 1 to 9.

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