Preparation method of nanofiltration membrane with high chlorine resistance and pollution resistance

Abstract

The application discloses a preparation method of a nanofiltration membrane with high chlorine resistance and pollution resistance. The nanofiltration membrane is prepared by the following steps: on the basis of an activated polytetrafluoroethylene microporous membrane, sequentially performing impregnation of an amine monomer and an acyl chloride monomer, then performing heat treatment, then grafting an amine group containing cyclic substance, and finally introducing a quaternary ammonium modification. The nanofiltration membrane prepared by the method has a magnesium sulfate retention rate of 98.0% after exposure to 24000 ppm.h of active chlorine, and the water flux recovery rate of bovine serum albumin is 95.0%, which is almost unchanged compared with that before exposure. It is shown that the nanofiltration membrane has excellent chlorine resistance and good pollution resistance.

Description

Technical Field

[0001] This invention relates to a method for preparing composite membranes, specifically a method for preparing a nanofiltration membrane with high chlorine resistance and antifouling properties. Background Technology

[0002] Membrane separation technology plays a crucial role in water treatment. Nanofiltration membranes, situated between osmosis and reverse osmosis, offer significant advantages such as low operating pressure and high flux. They exhibit good retention rates for substances with molecular weights between 200 and 1000 Da and are widely used in drinking water softening, heavy metal ion removal from wastewater, concentration and purification in the biopharmaceutical industry, and the treatment of concentrated brine. In practical water treatment applications, large amounts of active chlorine are often added to the feed solution. Even after pretreatment with activated carbon, residual active chlorine can attack the nanofiltration membrane surface during long-term operation, leading to a sharp decline or even failure of membrane performance. The chlorine resistance of membranes has become one of the technical bottlenecks limiting the widespread application of membrane separation technology. Furthermore, the antifouling performance of membranes remains another technical bottleneck restricting the widespread application of membrane separation technology.

[0003] Patent CN103331110A describes the preparation of a fouling-resistant and chlorine-resistant composite membrane by immersing a polyamide reverse osmosis composite membrane in a solution of an antifouling, chlorine-resistant, hydrophilic terpolymer. Patent CN102284252A improves the chlorine resistance of the reverse osmosis composite membrane by adding an epoxy-group binder to the casting solution. Patent CN104023830A prepares a fluorinated polyamide layer using an aqueous solution of an epoxy-terminated fluorine compound, resulting in a chlorine-resistant water treatment membrane. Regarding chlorine resistance in nanofiltration membranes, patents CN105771700A and CN107754617A both use mixed diamines via interfacial polymerization to prepare chlorine-resistant nanofiltration membranes. Summary of the Invention

[0004] In order to solve the problems existing in the background art, the purpose of this invention is to provide a method for preparing a nanofiltration membrane with high chlorine resistance and antifouling properties.

[0005] The steps of the technical solution adopted in this invention are as follows:

[0006] (1) Activation: The polytetrafluoroethylene microporous membrane was treated with an aqueous solution of sodium dodecylbenzenesulfonate to obtain an active base membrane;

[0007] (2) Aqueous phase impregnation: The active base membrane described in step (1) is immersed in an aqueous solution of amine monomers and left to stand. It is then taken out and placed in the air to dry, thus obtaining the first intermediate membrane.

[0008] (3) Oil phase impregnation: The first intermediate film described in step (2) is immersed in an organic solvent solution of acyl chloride monomer and left to stand, and then placed in the air to dry to obtain the second intermediate film;

[0009] (4) Post-processing: Rinse the second intermediate membrane with deionized water and then place it in a drying oven to obtain the third intermediate membrane;

[0010] (5) The nanofiltration membrane is obtained by grafting and quaternizing the third intermediate membrane in sequence.

[0011] The polytetrafluoroethylene microporous membrane is a polytetrafluoroethylene flat sheet membrane or a polytetrafluoroethylene hollow fiber membrane.

[0012] The specific step (1) is as follows: immerse the polytetrafluoroethylene microporous membrane in a sodium dodecylbenzenesulfonate aqueous solution with a mass concentration of 0.1% to 4.0%, leave it for 5 min to 12 h, and then take it out and air dry it to obtain an active base membrane.

[0013] The specific step (2) involves immersing the active base film in an aqueous solution of amine monomers with a mass concentration of 0.1% to 5.0% for 5 seconds to 30 minutes.

[0014] The amine monomer in step (2) is any one of piperazine, p-phenylenediamine, m-phenylenediamine, o-phenylenediamine, ethylenediamine, hexamethylenediamine, triethylamine, o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, and methyldiethanolamine, or a mixture of both in any proportion.

[0015] The specific step (3) involves immersing the first intermediate membrane in an organic solvent solution of acyl chloride monomers with a mass concentration of 0.1% to 5.0% for 5 seconds to 30 minutes.

[0016] The acyl chloride monomer in step (3) is any one of pyromellitic chloride, isophthalic chloride, terephthalic chloride and phthalic chloride or a mixture of the two in any proportion.

[0017] The organic solvent in step (3) is any one of n-hexane, toluene, n-octane, ethyl acetate, isooctane, and n-heptane.

[0018] The specific step (4) involves placing the item in a drying oven at 30~100℃ for 1~30 minutes.

[0019] Step (5) specifically involves:

[0020] (5.1) Grafting modification: The third intermediate membrane was immersed in an aqueous solution containing an amino cyclic compound at a mass concentration of 0.01% to 5.0% at 20~70 ℃ for 10 min to 3 h, then removed and dried to obtain the fourth intermediate membrane;

[0021] (5.2) Quaternization modification: The fourth intermediate membrane is immersed in an aqueous solution of 3-bromopropionic acid or 1,3-propanesulfonic acid lactone at a mass concentration of 0.01% to 5.0% at 20~70 ℃ for 0.5 h to 12 h, then removed and dried to obtain a nanofiltration membrane with high chlorine resistance and antifouling properties.

[0022] The amine-containing cyclic compound in step (5.1) is any one of triaminopyrimidine, melamine, etc., or a mixture of both in any proportion.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] This invention involves simple activation of a polytetrafluoroethylene membrane, followed by impregnation with amine monomers and acyl chloride monomers, then heat treatment, grafting with amine-containing cyclic compounds, and finally introducing quaternization modification to obtain a nanofiltration membrane with high chlorine resistance and antifouling properties.

[0025] The nanofiltration membrane prepared in this invention exhibits a magnesium sulfate rejection rate of 98.0% after exposure to 24,000 ppm·h of active chlorine (immersion in 2,000 ppm NaClO solution for 12 h), which is almost unchanged compared to before exposure.

[0026] Furthermore, the nanofiltration membrane prepared by this invention achieves a water flux recovery rate of 95.0% for bovine serum albumin, indicating that the nanofiltration membrane possesses excellent chlorine resistance and good antifouling properties. This invention effectively solves the technical bottlenecks of existing nanofiltration membranes' inability to withstand active chlorine corrosion and their susceptibility to fouling, greatly promoting the widespread application of nanofiltration membranes. Detailed Implementation

[0027] The present invention will be further described below with reference to specific embodiments, but the present invention is not limited to the following embodiments.

[0028] The embodiments of the present invention are as follows: Example

[0029] (1) Activation: Immerse the polytetrafluoroethylene flat sheet membrane in a 0.1% (w / w) sodium dodecylbenzenesulfonate aqueous solution for 12 hours; remove it and air dry it to obtain the active base membrane;

[0030] (2) Aqueous phase impregnation: The active base membrane described in step (1) is immersed in an aqueous solution of piperazine with a mass concentration of 5.0% for 30 minutes, then removed and air-dried to obtain the first intermediate membrane;

[0031] (3) Oil phase impregnation: The first intermediate membrane described in step (2) is immersed in a hexane solution of 5.0% mass concentration of trimesoyl chloride for 5 seconds, and then placed in the air to dry to obtain the second intermediate membrane;

[0032] (4) Post-treatment: Rinse the second intermediate membrane with deionized water, then place it in a drying oven at 100°C for 1 minute, and take it out to obtain the third intermediate membrane;

[0033] (5) Grafting modification: Immerse the third intermediate membrane described in step (4) in a 5.0% mass concentration triaminopyrimidine aqueous solution at 20°C for 10 min, remove and air dry to obtain the fourth intermediate membrane;

[0034] (6) Quaternization modification: The fourth intermediate membrane described in step (5) is immersed in a 3-bromopropionic acid aqueous solution with a mass concentration of 5.0% at 70 °C for 12 h, then removed and dried to obtain a nanofiltration membrane with high chlorine resistance and antifouling properties.

[0035] The prepared chlorine-resistant composite nanofiltration membrane was subjected to cross-flow filtration testing at 25°C and 0.2 MPa, showing a MgSO4 rejection rate of 98.2%. Then, it was immersed in 2000 ppm NaClO solution for 12 hours and then subjected to cross-flow filtration testing at 25°C and 0.2 MPa, showing a MgSO4 rejection rate of 98.0%. The nanofiltration membrane prepared in this invention showed a 95.0% recovery rate of bovine serum albumin water flux. Example

[0036] (1) Activation: Immerse the polytetrafluoroethylene hollow fiber membrane in a 4.0% (w / w) sodium dodecylbenzenesulfonate aqueous solution for 5 min; remove it and air dry it to obtain the active base membrane;

[0037] (2) Aqueous phase impregnation: Immerse the active base membrane described in step (1) in an aqueous solution of p-phenylenediamine with a mass concentration of 0.1% for 5 seconds, remove it and air dry it to obtain the first intermediate membrane;

[0038] (3) Oil phase impregnation: The first intermediate membrane described in step (2) is immersed in a toluene solution of isophthaloyl chloride with a mass concentration of 0.1% for 30 minutes, and then placed in the air to dry to obtain the second intermediate membrane;

[0039] (4) Post-treatment: Rinse the second intermediate membrane with deionized water, then place it in a drying oven at 30°C for 30 min, and take it out to obtain the third intermediate membrane;

[0040] (5) Grafting modification: The third intermediate membrane described in step (4) is immersed in an aqueous solution of a mixture of triaminopyrimidine and melamine (mass ratio of the two is 1:2) at 70 °C and 0.01% by mass, and left for 3 h. Then it is taken out and dried to obtain the fourth intermediate membrane.

[0041] (6) Quaternization modification: The fourth intermediate membrane described in step (5) is immersed in an aqueous solution of 1,3-propanesulfonic acid lactone with a mass concentration of 0.01% at 20°C for 0.5 h, then removed and dried to obtain a nanofiltration membrane with high chlorine resistance and antifouling properties.

[0042] The prepared chlorine-resistant composite nanofiltration membrane was subjected to cross-flow filtration testing at 25°C and 0.2 MPa, showing a MgSO4 rejection rate of 98.3%. Then, it was immersed in 2000 ppm NaClO solution for 12 hours and then subjected to cross-flow filtration testing at 25°C and 0.2 MPa, showing a MgSO4 rejection rate of 98.0%. The nanofiltration membrane prepared in this invention showed a 94.9% recovery rate of bovine serum albumin water flux. Example

[0043] (1) Activation: Immerse the polytetrafluoroethylene flat sheet membrane in a 2.0% (w / w) sodium dodecylbenzenesulfonate aqueous solution for 8 hours; remove it and air dry it to obtain the active base membrane;

[0044] (2) Aqueous phase immersion: Immerse the active base membrane described in step (1) in an aqueous solution of m-phenylenediamine with a mass concentration of 3.0% for 20 minutes, remove it and air dry it to obtain the first intermediate membrane;

[0045] (3) Oil phase impregnation: The first intermediate membrane described in step (2) is immersed in a 3.0% mass concentration of terephthaloyl chloride in n-octane solution, left for 15 minutes, and then placed in the air to dry to obtain the second intermediate membrane;

[0046] (4) Post-treatment: Rinse the second intermediate membrane with deionized water, then place it in a drying oven at 60°C for 10 min, and take it out to obtain the third intermediate membrane;

[0047] (5) Grafting modification: The third intermediate membrane described in step (4) is immersed in a melamine solution with a mass concentration of 3.0% at 50 °C for 2 h, then removed and dried to obtain the fourth intermediate membrane;

[0048] (6) Quaternization modification: The fourth intermediate membrane described in step (5) is immersed in a 4.0% mass concentration of 3-bromopropionic acid aqueous solution at 60 °C for 8 h, then removed and dried to obtain a nanofiltration membrane with high chlorine resistance and antifouling properties.

[0049] The prepared chlorine-resistant composite nanofiltration membrane was subjected to cross-flow filtration testing at 25°C and 0.2 MPa, showing a MgSO4 rejection rate of 98.1%. Then, it was immersed in 2000 ppm NaClO solution for 12 hours and then subjected to cross-flow filtration testing at 25°C and 0.2 MPa, showing a MgSO4 rejection rate of 98.0%. The nanofiltration membrane prepared in this invention showed a 94.8% recovery rate of bovine serum albumin water flux. Example

[0050] (1) Activation: Immerse the polytetrafluoroethylene flat sheet membrane in a 1.0% (w / w) sodium dodecylbenzenesulfonate aqueous solution for 2 hours; remove it and air dry it to obtain the active base membrane;

[0051] (2) Aqueous phase immersion: Immerse the active base membrane described in step (1) in an aqueous solution of 1.0% by mass of phthalic acid, leave for 10 minutes, take it out and air dry to obtain the first intermediate membrane;

[0052] (3) Oil phase impregnation: The first intermediate membrane described in step (2) is immersed in an ethyl acetate solution of a mixture of 1.0% mass concentration of trimesoyl chloride and isophthaloyl chloride (mass ratio of the two is 1:3), left for 10 min, and then placed in the air to dry to obtain the second intermediate membrane;

[0053] (4) Post-treatment: Rinse the second intermediate membrane with deionized water, then place it in a drying oven at 50°C for 5 min, and take it out to obtain the third intermediate membrane;

[0054] (5) Grafting modification: The third intermediate membrane described in step (4) is immersed in an aqueous solution of a mixture of triaminopyrimidine and melamine (mass ratio of the two is 3:1) at 60 °C for 1 h, then removed and dried to obtain the fourth intermediate membrane;

[0055] (6) Quaternization modification: The fourth intermediate membrane described in step (5) is immersed in an aqueous solution of 1,3-propanesulfonic acid lactone at 40 °C and 1.0% by mass for 1 h, then removed and dried to obtain a nanofiltration membrane with high chlorine resistance and antifouling properties.

[0056] The prepared chlorine-resistant composite nanofiltration membrane was subjected to cross-flow filtration testing at 25°C and 0.2 MPa, showing a MgSO4 rejection rate of 98.0%. Then, it was immersed in 2000 ppm NaClO solution for 12 hours and then subjected to cross-flow filtration testing at 25°C and 0.2 MPa, again showing a MgSO4 rejection rate of 98.0%. The nanofiltration membrane prepared in this invention exhibits a 95.0% recovery rate of bovine serum albumin water flux. Example

[0057] (1) Activation: Immerse the polytetrafluoroethylene hollow fiber membrane in a 3.0% (w / w) sodium dodecylbenzenesulfonate aqueous solution for 6 hours; remove it and air dry it to obtain the active base membrane;

[0058] (2) Aqueous phase impregnation: The active base membrane described in step (1) is immersed in a mixed aqueous solution of piperazine and m-phenylenediamine with a mass concentration of 2.0% (piperazine / m-phenylenediamine mass ratio of 1:1) for 15 minutes, then removed and air-dried to obtain the first intermediate membrane;

[0059] (3) Oil phase impregnation: The first intermediate membrane described in step (2) is immersed in a n-heptane solution containing a mixture of isophthaloyl chloride and phthaloyl chloride (mass ratio of the two is 2:3) with a mass concentration of 2.0%, and left for 20 minutes. Then it is placed in the air to dry to obtain the second intermediate membrane.

[0060] (4) Post-treatment: Rinse the second intermediate membrane with deionized water, then place it in a drying oven at 70°C for 15 minutes, and take it out to obtain the third intermediate membrane;

[0061] (5) Grafting modification: The third intermediate membrane described in step (4) is immersed in a 40 °C solution of a mixture of triaminopyrimidine and melamine (mass ratio of the two is 5:3) with a mass concentration of 4.0%, left for 1.5 h, taken out and dried to obtain the fourth intermediate membrane;

[0062] (6) Quaternization modification: The fourth intermediate membrane described in step (5) is immersed in an aqueous solution of 1,3-propanesulfonic acid lactone with a mass concentration of 3.0% at 50 °C for 3 h, then removed and dried to obtain a nanofiltration membrane with high chlorine resistance and antifouling properties.

[0063] The prepared chlorine-resistant composite nanofiltration membrane was subjected to cross-flow filtration testing at 25°C and 0.2 MPa, showing a MgSO4 rejection rate of 98.3%. Then, it was immersed in 2000 ppm NaClO solution for 12 hours and subsequently subjected to cross-flow filtration testing at 25°C and 0.2 MPa, showing a MgSO4 rejection rate of 98.0%. The nanofiltration membrane prepared in this invention exhibits a 94.8% water flux recovery rate for bovine serum albumin. Example

[0064] (1) Activation: Immerse the polytetrafluoroethylene flat sheet membrane in a 1.5% (w / w) sodium dodecylbenzenesulfonate aqueous solution for 3 hours; remove it and air dry it to obtain the active base membrane;

[0065] (2) Aqueous phase immersion: Immerse the active base membrane described in step (1) in a mixed aqueous solution of o-phenylenediamine and m-phenylenediamine (mass ratio of o-phenylenediamine / m-phenylenediamine is 2:1) with a mass concentration of 4.0% and leave it for 5 minutes. Then take it out and air dry it to obtain the first intermediate membrane.

[0066] (3) Oil phase impregnation: The first intermediate membrane described in step (2) is immersed in a hexane solution containing a mixture of phthaloyl chloride and trimesoyl chloride (mass ratio of 1:4) with a mass concentration of 4.0% for 5 minutes, and then placed in the air to dry to obtain the second intermediate membrane.

[0067] (4) Post-treatment: Rinse the second intermediate membrane with deionized water, then place it in a drying oven at 70°C for 20 min, and take it out to obtain the third intermediate membrane;

[0068] (5) Grafting modification: Immerse the third intermediate membrane described in step (4) in a 2.5% mass concentration triaminopyrimidine aqueous solution at 55 °C for 30 min, remove and air dry to obtain the fourth intermediate membrane;

[0069] (6) Quaternization modification: The fourth intermediate membrane described in step (5) is immersed in a 2.5% mass concentration of 3-bromopropionic acid aqueous solution at 55 °C for 6 h, then removed and dried to obtain a nanofiltration membrane with high chlorine resistance and antifouling properties.

[0070] The prepared chlorine-resistant composite nanofiltration membrane was subjected to cross-flow filtration testing at 25°C and 0.2 MPa, showing a MgSO4 rejection rate of 98.1%. Then, it was immersed in 2000 ppm NaClO solution for 12 hours and then subjected to cross-flow filtration testing at 25°C and 0.2 MPa, showing a MgSO4 rejection rate of 98.0%. The nanofiltration membrane prepared in this invention showed a 95.0% recovery rate of bovine serum albumin water flux.

[0071] Comparative Example 1

[0072] The solution in Chinese patent 202110489309.1:

[0073] (1) Activation: Immerse the polytetrafluoroethylene microporous membrane in a 50% ethanol aqueous solution for 4 min. After draining, the active base membrane is obtained.

[0074] (2) Aqueous phase impregnation: Immerse the active base membrane described in step (1) in an aqueous solution of 0.5% by mass concentration of amine monomers, leave for 4 min, take it out and air dry to obtain the first intermediate membrane;

[0075] (3) Oil phase impregnation: The first intermediate membrane described in step (2) is immersed in a solution of 1.0% by mass of an organic solvent containing acyl chloride monomers, left for 4 min, and then placed in the air to dry to obtain the second intermediate membrane;

[0076] (4) Post-treatment: Rinse the second intermediate membrane with deionized water, then place it in a drying oven at 70 °C for 40 min, and take it out to obtain the third intermediate membrane.

[0077] (5) Crosslinking agent impregnation: The third intermediate membrane described in step (4) is immersed in a 0.05% mass concentration glutaraldehyde aqueous solution, left for 1.0 h, taken out and dried to obtain the fourth intermediate membrane.

[0078] (6) Grafting monomer impregnation: The fourth intermediate membrane described in step (5) is immersed in a 2.0% mass concentration aqueous solution of m-aminoacetanilide for 2.0 h, then removed and dried to obtain the fifth intermediate membrane.

[0079] (7) Post-treatment: Rinse the fifth intermediate membrane described in step (6) with deionized water, then place it in a drying oven at 60°C for 20 min, and take it out to obtain a chlorine-resistant composite nanofiltration membrane.

[0080] The prepared chlorine-resistant composite nanofiltration membrane was subjected to cross-flow filtration tests at 25℃ and 0.2 MPa, showing a MgSO4 rejection rate of 94.4%. Then, it was immersed in a 500 mg / L active chlorine solution for 2 hours, and then subjected to cross-flow filtration tests at 25℃ and 0.2 MPa, showing a MgSO4 rejection rate of 91.0%. The rejection rate of the chlorine-resistant composite nanofiltration membrane decreased by 3.6% before and after chlorination.

[0081] Comparative Example 2

[0082] The solution in Chinese patent 202210502139.0:

[0083] (1) Preparation of amphoteric complex:

[0084] 5g of polyethyleneimine and 1g of heptafluorobutyric acid were dissolved in 100ml of deionized water and reacted at 60℃ for 0.5 h to generate an amine compound. 3ml of hydroxyethyl acrylate and 3ml of 2-bromo-2-methylpropionyl bromide were dissolved in 20ml of tetrahydrofuran aqueous solution (tetrahydrofuran to water volume ratio 1:1) and reacted at 60℃ for 12 h. After filtration, the product was washed with deionized water and dried to obtain intermediate 1. 10g of the amine compound and 2g of intermediate 1 were dissolved in 50ml of methanol aqueous solution (methanol to water volume ratio 2:1) and reacted at 60℃ for 12 h. After filtration, the product was washed with deionized water and dried to obtain intermediate 2. 10g of intermediate 2, 1.5g of octadecyl dimethyl sulfopropyl betaine, 0.5g of methacrylate sulfopropyl betaine, and 0.06g of cuprous iodide were dissolved in 60ml of methanol aqueous solution (methanol to water volume ratio of 3:1). The reaction was carried out at 60℃ for 48 h. The amphoteric complex was obtained by methanol precipitation, filtration, washing, and drying.

[0085] (2) Activation and aqueous phase impregnation:

[0086] The hydrophobic polytetrafluoroethylene hollow fiber membrane was first immersed in a 5.0% sodium dodecylbenzenesulfonate aqueous solution for 10 minutes, and then removed and air-dried.

[0087] Then, the dried polytetrafluoroethylene hollow fiber membrane was immersed in an aqueous solution of 0.1% amphoteric compound for 30 min, and then removed and dried to obtain the first intermediate membrane.

[0088] (3) Oil phase impregnation: The first intermediate membrane is immersed in a cyclohexane solution of isobenzoic acid chloride with a mass concentration of 5.0% for 30 s, and then taken out and dried to obtain the second intermediate membrane;

[0089] (4) Post-treatment: Rinse the second intermediate membrane with deionized water, place it in a drying oven at 100°C for a period of time, leave it for 1 minute, and take it out to obtain a composite nanofiltration membrane with improved antifouling performance.

[0090] The prepared composite nanofiltration membrane was subjected to cross-flow filtration tests at 25℃ and 0.4 MPa, and the rejection rate of MgSO4 was 86.5%. The flux recovery rate (FRR) of the prepared composite nanofiltration membrane for washing 0.2 g / L bovine serum albumin solution was 97.3% at 25℃ and 0.4 MPa.

Claims

1. A method for preparing a nanofiltration membrane with high chlorine resistance and antifouling properties, characterized in that, The steps are as follows: (1) Activation: The polytetrafluoroethylene microporous membrane was treated with an aqueous solution of sodium dodecylbenzenesulfonate to obtain an active base membrane; (2) Aqueous phase impregnation: The active base membrane described in step (1) is immersed in an aqueous solution of amine monomers and left to stand. It is then taken out and placed in the air to dry, thus obtaining the first intermediate membrane. (3) Oil phase impregnation: The first intermediate film described in step (2) is immersed in an organic solvent solution of acyl chloride monomer and left to stand, and then placed in the air to dry to obtain the second intermediate film; (4) Post-processing: Rinse the second intermediate membrane with deionized water and then place it in a drying oven to obtain the third intermediate membrane; (5) The nanofiltration membrane is obtained by sequentially grafting and quaternizing the third intermediate membrane; Step (5) specifically involves: (5.1) Grafting modification: The third intermediate membrane was immersed in an aqueous solution containing an amino cyclic compound at a mass concentration of 0.01% to 5.0% at 20~70 ℃ for 10 min to 3 h, then removed and dried to obtain the fourth intermediate membrane; The amine-containing cyclic compound in step (5.1) is any one of triaminopyrimidine and melamine or a mixture of the two in any proportion; (5.2) Quaternization modification: The fourth intermediate membrane is immersed in an aqueous solution of 3-bromopropionic acid or 1,3-propanesulfonic acid lactone at a mass concentration of 0.01% to 5.0% at 20~70 ℃ for 0.5 h to 12 h, then removed and dried to obtain a nanofiltration membrane with high chlorine resistance and antifouling properties.

2. The method for preparing a nanofiltration membrane with high chlorine resistance and antifouling properties according to claim 1, characterized in that: The specific step (1) is as follows: immerse the polytetrafluoroethylene microporous membrane in a sodium dodecylbenzenesulfonate aqueous solution with a mass concentration of 0.1% to 4.0%, leave it for 5 min to 12 h, and then take it out and air dry it to obtain an active base membrane.

3. The method for preparing a nanofiltration membrane with high chlorine resistance and antifouling properties according to claim 1, characterized in that: The specific step (2) involves immersing the active base film in an aqueous solution of amine monomers with a mass concentration of 0.1% to 5.0% for 5 seconds to 30 minutes.

4. The method for preparing a nanofiltration membrane with high chlorine resistance and antifouling properties according to claim 1, characterized in that: The amine monomer in step (2) is any one of piperazine, p-phenylenediamine, m-phenylenediamine, o-phenylenediamine, ethylenediamine, hexamethylenediamine, triethylamine, o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, and methyldiethanolamine, or a mixture of both in any proportion.

5. The method for preparing a nanofiltration membrane with high chlorine resistance and antifouling properties according to claim 1, characterized in that: The specific step (3) involves immersing the first intermediate membrane in an organic solvent solution of acyl chloride monomers with a mass concentration of 0.1% to 5.0% for 5 seconds to 30 minutes.

6. The method for preparing a nanofiltration membrane with high chlorine resistance and antifouling properties according to claim 1, characterized in that: The acyl chloride monomer in step (3) is any one of pyromellitic chloride, isophthalic chloride, terephthalic chloride and phthalic chloride or a mixture of the two in any proportion.

7. The method for preparing a nanofiltration membrane with high chlorine resistance and antifouling properties according to claim 1, characterized in that: The organic solvent in step (3) is any one of n-hexane, toluene, n-octane, ethyl acetate, isooctane, and n-heptane.

8. The method for preparing a nanofiltration membrane with high chlorine resistance and antifouling properties according to claim 1, characterized in that: The specific step (4) involves placing the item in a drying oven at 30~100℃ for 1~30 minutes.