High-flux renewable chlorine-resistant reverse osmosis composite membrane and preparation method thereof

Abstract

The invention belongs to the technical field of reverse osmosis membranes, and particularly relates to a high-flux reproducible chlorine-resistant reverse osmosis composite membrane and a preparation method thereof.Monomer 3, 5-diamino-1, 2, 4-triazole is added into a water-phase solution, functional amino and imino groups of the monomer react with acyl chloride groups, and the high-flux reproducible chlorine-resistant reverse osmosis composite membrane is prepared by adjusting the structure of a polyamide layer; the separation performance of the membrane can be improved while the water flux of the membrane is not obviously reduced. According to the reverse osmosis composite membrane preliminarily obtained through interfacial polymerization reaction, aniline dimer diaminodiphenylamine is adopted as a modification material, and chemical grafting modification of the membrane surface is carried out on a polyamide composite membrane. The characteristic that the redox potential of a secondary amine group on diaminodiphenylamine is lower than that of an amide group on a polyamide polymer is utilized, the secondary amine group can serve as a sacrificial group to react with active chlorine preferentially, protection of a polyamide separation layer is achieved, and therefore the chlorine resistance of the composite membrane is improved. In addition, diaminodiphenylamine has the same reversible redox characteristic as aniline, and reversible regeneration of chlorine resistance of the grafted membrane can be realized through Na2S2O3 reduction; therefore, the high-flux reproducible chlorine-resistant reverse osmosis composite membrane disclosed by the invention is a reverse osmosis composite membrane based on aniline dimer surface modification, and has the characteristics of high flux, reproducibility, excellent chlorine resistance, good water separation performance, better hydrophilicity and salt rejection rate.

Description

Technical Field

[0001] The invention belongs to the technical field of reverse osmosis membranes, and in particular relates to a high-flux regenerable chlorine-resistant reverse osmosis composite membrane and a preparation method thereof. Background Art

[0002] As an advanced membrane separation technology, reverse osmosis membrane technology has been widely used in seawater and brackish water desalination, pure and ultrapure water production, drinking water purification, industrial water and wastewater reuse, and achieving standard or zero (near-zero) emissions. Its contribution to sustainable economic and social development is becoming increasingly significant. However, the membranes have also exposed many problems during use, including suboptimal permeate flux, susceptibility to contamination, and poor chlorine resistance. To make reverse osmosis membrane technology a more effective separation method, two further issues need to be addressed: first, improving the anti-fouling and chlorine tolerance of reverse osmosis membranes; second, while ensuring high salt rejection rates, developing high-flux polyamide composite reverse osmosis membranes and achieving industrial production through simple and efficient processes, thereby further promoting reverse osmosis membrane technology.

[0003] In industrial applications, membrane fouling is typically effectively controlled by pre-treating the composite membrane feed prior to filtration and cleaning the membrane after filtration. However, whether cleaning is done physically or chemically, polyamide membranes are highly susceptible to attack by active chlorine, leading to performance degradation. Therefore, achieving high membrane flux while also addressing the composite membrane's chlorine resistance presents a significant technical challenge.

[0004] The prior art mentions that regulating the structural morphology of polyamide composite membranes by introducing new amine monomers and coating or grafting a polymer sacrificial layer onto the polyamide layer are effective means of increasing the water flux of the composite membrane, optimizing the water separation performance of the membrane, and improving the chlorine resistance of the composite membrane. For example, patent publication number CN114307683A discloses a method for modifying a regenerable chlorine-resistant high-flux polyamide composite membrane. This invention loads ABTS onto the polyamide layer through chemical bonding, effectively preventing active chlorine from diffusing into the polyamide layer, and forming a polyamide composite membrane with chlorine resistance. However, this solution does not significantly improve the desalination rate and cannot guarantee water flux and retention rate while taking into account chlorine resistance.

[0005] For example, patent publication number CN110201563A discloses a method for preparing a chlorine-resistant and pollution-resistant polyamide reverse osmosis membrane. The beneficial effects are: 1. By introducing silver nitrate electronic groups on the acyl chloride benzene ring, the chlorine resistance of the polyamide reverse osmosis membrane is greatly enhanced without affecting the permeability of the polyamide reverse osmosis membrane; 2. By modifying the surface of the polyamide reverse osmosis membrane and introducing organic nanofiber dispersion and MOFs aqueous dispersion onto the surface of the polyamide reverse osmosis membrane, a polyamide reverse osmosis membrane with chlorine resistance and pollution resistance and excellent separation performance is constructed. However, this solution requires repeated assembly during the preparation of the reverse osmosis membrane, which is time-consuming and labor-intensive, and cannot achieve regenerative chlorine resistance of the reverse osmosis membrane.

[0006] Therefore, it is of great significance to improve the chlorine resistance of reverse osmosis membranes, especially to achieve the regeneration of chlorine resistance. Summary of the Invention

[0007] In view of the deficiencies in the prior art, the present invention provides a high-flux regenerable chlorine-resistant reverse osmosis composite membrane and a preparation method thereof.

[0008] This is achieved specifically through the following technical solutions:

[0009] A method for preparing a high-flux, regenerable, chlorine-resistant reverse osmosis composite membrane, wherein the high-flux, regenerable, chlorine-resistant reverse osmosis composite membrane is a diaminodiphenylamine-grafted reverse osmosis polyamide composite membrane, and the preparation method comprises the following steps:

[0010] Step 1: Preparation of reverse osmosis polyamide composite membrane

[0011] 1.1 Prepare a polymer solution with a mass concentration of 18% as a casting solution, apply the casting solution on a non-woven fabric, and immerse it in a coagulation bath to form a support layer to prepare a polymer base membrane;

[0012] 1.2 Soak the polymer base film in a 0.3% sodium bisulfite solution for 30 minutes, then remove the polymer base film and rinse it with deionized water, then soak it in a 30% isopropyl alcohol solution for 30 minutes, and finally rinse it thoroughly with deionized water;

[0013] 1.3 Immerse the polymer base film in the aqueous solution for 1-5 minutes, then remove the base film and remove excess water droplets on its surface with an air knife. Then, immerse it in the polyacyl chloride oil solution at room temperature for 1-5 minutes.

[0014] 1.4 The polymer membrane obtained in step 1.3 is heat-treated at 35-75°C for 1-10 minutes, then washed with citric acid solution to remove residual substances on the membrane surface, then rinsed with deionized water for 1-10 minutes, and then immersed in a 5.0% glycerol aqueous solution for 1-10 minutes for moisturizing treatment;

[0015] 1.5 The membrane obtained in step 4) is heat-treated in an oven at 70° C. for 1-20 min to obtain a reverse osmosis polyamide composite membrane;

[0016] Step 2 Preparation of diaminodiphenylamine grafted reverse osmosis polyamide composite membrane

[0017] 2.1 Weigh diaminodiphenylamine, grind it thoroughly in a mortar and pestle, and dissolve it in ethanol to prepare a diaminodiphenylamine ethanol solution with a mass concentration of 1-10%. Ultrasonicate it for 5 minutes to fully dissolve it.

[0018] 2.2 Weigh glutaraldehyde and fully dissolve it in pure water to prepare a glutaraldehyde aqueous solution with a mass concentration of 1-40%;

[0019] 2.3 Pour the diaminodiphenylamine ethanol solution onto the surface of the reverse osmosis polyamide composite membrane, allowing the membrane surface to contact with the ethanol solution for 2 minutes at room temperature, then rinse the modified membrane surface with ethanol solution and deionized water several times, and soak it in deionized water to remove the residual modification solvent and ungrafted dimer on the membrane surface, and then store it in deionized water for later use;

[0020] 2.4 Immerse the modified membrane in step 2.3 in a glutaraldehyde crosslinker solution for 1-20 minutes, then place it in an oven at 60-80°C for heat treatment for 1-20 minutes;

[0021] 2.5 The membrane prepared in step 2.4 is subjected to chlorination reaction and chlorination reduction post-treatment in sequence to obtain a diaminodiphenylamine grafted reverse osmosis polyamide composite membrane.

[0022] The polymer is at least one of polyethersulfone, polyacrylonitrile, bisphenol A polysulfone, polyvinylidene fluoride, and polyvinyl chloride.

[0023] The aqueous phase solution is composed of the following substances by mass fraction: 1.0-8.0 wt% of m-phenylenediamine, 0.05-2.0 wt% of 3,5-diamino-1,2,4-triazole, 1.0-7.0 wt% of camphorsulfonic acid, 1.0-4 wt% of triethylamine, 0.05-0.2 wt% of sodium hydroxide, and the balance is water.

[0024] The pH of the aqueous solution is 9-11.

[0025] The mass concentration of the polyacyl chloride in the polyacyl chloride oil phase solution is 0.05-0.5%, and the balance is organic solvent.

[0026] The polybasic acid chloride is one or more of trimesoyl chloride, terephthaloyl chloride, oxalyl chloride, etc.; the organic solvent is one or more of dichloromethane, n-hexane, ethylcyclohexane, toluene, xylene, m-xylene, mesitylene, isopar E, isopar G, isopar H, isopar M, etc.

[0027] The mass concentration of the citric acid solution is 12%, the washing time is 1-20 minutes, and the temperature is 50°C.

[0028] The chlorination reaction is to wash the membrane with deionized water and sodium hypochlorite solution in sequence, then immerse the membrane surface in sodium hypochlorite solution for chlorination, and then use deionized water to remove the active chlorine remaining on the membrane surface.

[0029] The chlorination reduction post-treatment is to first place the membrane in an active chlorine solution for treatment, and then place it in a Na2S2O3 solution for constant temperature oscillation reduction.

[0030] A high-flux regenerable chlorine-resistant reverse osmosis composite membrane is prepared by the method.

[0031] The present invention adds the monomer 3,5-diamino-1,2,4-triazole to the aqueous solution, and its functional amino and imino groups react with the acyl chloride groups. By adjusting the structure of the polyamide layer, the separation performance of the membrane can be improved without significantly reducing the water flux of the membrane. The reverse osmosis composite membrane initially obtained by the interfacial polymerization reaction uses the aniline dimer diaminodiphenylamine as a modification material to chemically graft the surface of the polyamide composite membrane. Taking advantage of the fact that the redox potential of the secondary amine group on diaminodiphenylamine is lower than that of the amide group on the polyamide polymer, it can act as a sacrificial group to preferentially react with active chlorine, thereby protecting the polyamide separation layer and improving the chlorine resistance of the composite membrane. In addition, diaminodiphenylamine has the same reversible redox characteristics as aniline, and can achieve reversible regeneration of the chlorine resistance of the grafted membrane through Na2S2O3 reduction.

[0032] This method utilizes the electrostatic interaction between aniline cations and the membrane surface, and the spontaneous oxidative polymerization of aniline on the polyamide membrane surface, to construct a high-density intrinsic polyaniline modified layer on the reverse osmosis membrane surface. Long-chain polyaniline has more reversible redox functional groups than short-chain dimers, which helps improve the membrane's regenerative chlorine resistance.

[0033] Furthermore, while the grafted macromolecular benzene rings reduce the hydrophilicity of the polyamide membrane surface to a certain extent, the grafting reaction also introduces more -NH groups onto the membrane surface, compensating for the negative impact of the benzene rings on membrane hydrophilicity. The combined effect of these two factors improves the membrane's salt rejection rate without significantly reducing membrane flux.

[0034] Beneficial effects:

[0035] The high-flux regenerable chlorine-resistant reverse osmosis composite membrane of the present invention is a reverse osmosis composite membrane based on surface modification of aniline dimer, which has the characteristics of high flux, regeneration, excellent chlorine resistance, good water separation performance, good hydrophilicity and desalination rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The SEM images of the membrane surfaces obtained in Examples 1-4 are shown; the upper left image is Example 1, the upper right image is Example 2, the lower left image is Example 3, and the lower right image is Example 4;

[0037] Figure 2 This is the SEM image of the membrane surface obtained in Comparative Example 1;

[0038] Figure 3 This is an SEM image of the membrane surface obtained in Comparative Example 2;

[0039] Figure 4 The diagram is a schematic diagram of the redox reaction of grafted diaminodiphenylamine in the high-flux regenerable chlorine-resistant reverse osmosis composite membrane of the present invention. DETAILED DESCRIPTION

[0040] The specific embodiments of the present invention are further described in detail below, but the present invention is not limited to these embodiments. Any improvement or replacement based on the basic spirit of the present embodiment still falls within the scope of protection required by the claims of the present invention.

[0041] Example 1

[0042] A method for preparing a high-flux, regenerable, chlorine-resistant reverse osmosis composite membrane, wherein the high-flux, regenerable, chlorine-resistant reverse osmosis composite membrane is a diaminodiphenylamine-grafted reverse osmosis polyamide composite membrane, and the preparation method comprises the following steps:

[0043] Step 1: Preparation of reverse osmosis polyamide composite membrane

[0044] 1.1 Prepare a polymer solution with a mass concentration of 18% as a casting solution, apply the casting solution on a non-woven fabric, and then immerse it in a coagulation water bath at 12°C, 20°C, and 60°C in sequence to allow the casting solution to solidify to form a polymer support layer, thereby preparing a polymer base membrane;

[0045] 1.2 Soak the polymer base film in a 0.3% sodium bisulfite solution for 30 minutes, then remove the polymer base film and rinse it with deionized water, then soak it in a 30% isopropyl alcohol solution for 30 minutes, and finally rinse it thoroughly with deionized water and dry it.

[0046] 1.3 The polymer base film was first immersed in an aqueous solution for full contact for 3 minutes, after which the base film was removed and excess water droplets on its surface were removed with an air knife. The base film was then immersed in a polyacyl chloride oil phase solution at room temperature for full contact for 3 minutes. The remaining acyl chloride oil phase solution was then poured off from above the membrane. The aqueous solution was formulated by mass as follows: 5% camphorsulfonic acid, 2% triethylamine, 0.03% sodium hydroxide, 6.0% m-phenylenediamine, 1.0% 3,5-diamino-1,2,4-triazole, and the balance was water. The mass concentration of the polyacyl chloride in the polyacyl chloride oil phase solution was 0.3%.

[0047] 1.4 The polymer membrane obtained in step 1.3 was heat-treated at 70°C for 5 minutes, then washed with citric acid solution to remove residual substances on the membrane surface, rinsed with deionized water for 10 minutes, and then immersed in a 5.0% glycerol aqueous solution for 5 minutes for moisturizing treatment;

[0048] 1.5 The membrane obtained in step 4) was heat-treated in an oven at 70° C. for 15 min to obtain a reverse osmosis polyamide composite membrane;

[0049] Step 2 Preparation of diaminodiphenylamine grafted reverse osmosis polyamide composite membrane

[0050] 2.1 Weigh diaminodiphenylamine, grind it thoroughly in a mortar and pestle, and dissolve it in ethanol to prepare a 0.5% diaminodiphenylamine ethanol solution. Ultrasonicate it for 5 minutes to fully dissolve it.

[0051] 2.2 Weigh glutaraldehyde and fully dissolve it in pure water to prepare a 5.0% glutaraldehyde aqueous solution;

[0052] 2.3 Pour the diaminodiphenylamine ethanol solution onto the surface of the reverse osmosis polyamide composite membrane, allowing the membrane surface to contact with the ethanol solution for 2 minutes at room temperature, then rinse the modified membrane surface with ethanol solution and deionized water several times, and soak it in deionized water to remove the residual modification solvent and ungrafted dimer on the membrane surface, and then store it in deionized water for later use;

[0053] 2.4 The modified membrane obtained in step 2.3 was immersed in a glutaraldehyde crosslinker solution for 15 minutes, and then placed in an oven at 70°C for heat treatment for 15 minutes to obtain a diaminodiphenylamine grafted reverse osmosis polyamide composite membrane;

[0054] 2.5 Take sodium hypochlorite containing 10% effective chlorine and dilute it with deionized water to a concentration of 1000ppm active chlorine solution, and adjust the pH value of the solution to 3-4 with hydrochloric acid and sodium hydroxide;

[0055] 2.6 Chlorination reaction: The membrane prepared in step 2.4 is subjected to chlorination reaction in sequence. The membrane is washed with deionized water and sodium hypochlorite aqueous solution in sequence, and then the membrane surface is immersed in the sodium hypochlorite aqueous solution prepared in step 2.5. The chlorinated membrane is thoroughly washed and immersed in deionized water to remove the active chlorine remaining on the surface;

[0056] 2.7 “Chlorination-reduction” treatment: first place the membrane in step 2.6 in a 1000ppm active chlorine solution for treatment for 3 hours. After the chlorinated composite membrane is thoroughly rinsed with deionized water, it is placed in a 1.0mol / LNa2S2O3 solution for constant temperature oscillation reduction for 3 hours, and then thoroughly rinsed with deionized water to obtain the diaminodiphenylamine grafted reverse osmosis polyamide composite membrane after “chlorination reaction” and “chlorination-reduction” treatment.

[0057] The polymer is bisphenol A type polysulfone.

[0058] The polybasic acid chloride is trimesoyl chloride; the organic solvent is a mixed solvent consisting of 3.0 wt% xylene, 17.0 wt% mesitylene, and 80.0 wt% isopar G.

[0059] Example 2

[0060] The difference from Example 1 is that a diaminodiphenylamine ethanol solution with a mass concentration of 1.0% is poured onto the surface of the preliminarily obtained polyamide composite membrane, and the other process steps and conditions are the same as those in Example 1.

[0061] Example 3

[0062] The difference from Example 1 is that a diaminodiphenylamine ethanol solution with a mass concentration of 1.5% is poured onto the surface of the preliminarily obtained polyamide composite membrane, and the other process steps and conditions are the same as those in Example 1.

[0063] Example 4

[0064] The difference from Example 1 is that a diaminodiphenylamine ethanol solution with a mass concentration of 2.0% is poured onto the surface of the preliminarily obtained polyamide composite membrane, and the other process steps and conditions are the same as those in Example 1.

[0065] Comparative Example 1

[0066] A method for preparing a reverse osmosis polyamide composite membrane comprises the following steps:

[0067] (1) preparing an 18 wt % polymer solution as a casting solution, coating the casting solution on a non-woven fabric by a doctor blade method, and then immersing the non-woven fabric in coagulation water baths at 12° C., 20° C., and 60° C. in sequence to allow the casting solution to coagulate to form a polymer support layer;

[0068] (2) Soak the prepared polymer base membrane in a 0.3wt% sodium bisulfite aqueous solution for 30 minutes, remove the base membrane, rinse it with deionized water, and soak it in a 30wt% isopropyl alcohol solution for 30 minutes, then rinse it thoroughly with deionized water and air dry it; immerse it in a mixed aqueous phase solution containing 5wt% camphorsulfonic acid, 2wt% triethylamine, 0.03wt% sodium hydroxide, 6.0wt% m-phenylenediamine, and 1.0wt% 3,5-diamino-1,2,4-triazole, and fully contact it for 3 minutes, remove the base membrane and remove excess water droplets on its surface. Then immerse it in an oil phase solution containing 0.30wt% polyacyl chloride, and fully contact it for 3 minutes to perform interfacial polymerization reaction to form a polyamide desalting layer, and pour the remaining acyl chloride oil phase solution from above the membrane;

[0069] (3) The membrane obtained in step (2) was thermally crosslinked at 70°C for 5 minutes. The membrane was then washed with a citric acid solution for 10 minutes, then rinsed with deionized water for 5 minutes, and then immersed in a 5.0 wt% glycerol aqueous solution for 3 minutes for moisturizing. Finally, the membrane was heat-treated in a 70°C oven for 10 minutes, cooled, and stored in deionized water. The remaining post-treatment processes and conditions were the same as those in 2.5, 2.6, and 2.7 of Example 1.

[0070] Comparative Example 2

[0071] The experimental conditions in Example 2 were selected as a comparative example for reference. The difference from Example 2 is that deionized water was used instead of Na2S2O3 for oscillation cleaning for 3 hours during the post-treatment "chlorination-reduction" treatment, and finally deionized water was used for thorough cleaning.

[0072] Ion removal performance

[0073] (1) The separation performance of Examples 1-4 and Comparative Example 1 was tested. Water-effect solution: The water flux and salt rejection of the membrane were tested under the conditions of an operating pressure of 100 psi and a temperature of 25°C. The water-effect solution was prepared by mixing 500 L of pure water, 39.5 g of NaCl, 94.5 g of CaCl2, 137.2 g of NaHCO3, 105.3 g of MgSO4·7H2O, and 2-3 mL of 10% effective chlorine of sodium hypochlorite in a certain proportion.

[0074] Table 1

[0075]

[0076]

[0077] (2) Regenerative chlorine resistance of the membrane: First, the surface of the polyamide reverse osmosis composite membrane was immersed in a 1000ppm active chlorine solution for 3 hours, then thoroughly rinsed with deionized water and placed in a 1.0mol / L Na2S2O3 solution for 3 hours of constant temperature oscillation reduction. Finally, it was thoroughly rinsed with deionized water. The above process was one cycle, and a total of three cycles were performed. Finally, the membrane performance was tested. The test results are shown in Table 2.

[0078] Table 2

[0079]

[0080] As shown in Table 1, in Examples 1-4, as the diaminodiphenylamine content increases from 0.5wt% to 2.0wt%, the membrane water flux gradually decreases. This is because: as the diaminodiphenylamine grafting concentration increases, the amount of diaminodiphenylamine grafted or adsorbed on the membrane surface also increases, and the permeation resistance to the reverse osmosis membrane will gradually increase, resulting in a continuous decrease in membrane flux. After 60 hours of chlorination reaction, the separation performance of the example membrane did not decrease significantly, while the comparative example after 60 hours of chlorination reaction, the water flux increased to 63.2GFD, and the salt rejection rate decreased to 92.5%. The reverse osmosis membrane prepared using the present invention can effectively improve the antioxidant performance against active chlorine and has a stronger tolerance to chlorine.

[0081] Table 2 shows the changes in membrane performance before and after chlorination reduction of the reverse osmosis membrane. In terms of membrane rejection, the salt rejection rates of Examples 1-4 and the comparative example all declined, but the degree of decline in the permeate flux of Comparative Examples 1 and 2 was much greater than that of the examples. After three cycles, the salt rejection rates of Examples 1-4 did not change much, and the salt rejection rates of the membranes could be restored through the reduction reaction. The salt rejection rates of Comparative Examples 1 and 2 dropped from 98.5% and 98.8% to 97.3% and 97.6%, respectively. This shows that the chlorine resistance of the membranes of Examples 1-4 can be restored through reduction treatment. This is because the secondary amine group of diaminodiphenylamine has a low redox potential and can preferentially react with active chlorine, thereby protecting the polyamide molecules, reducing the reversible N-Cl substitution of the amide bond, and weakening the degree of oxidation of the separation layer. On the other hand, after the grafted group undergoes reduction treatment, the quinone structure is reduced back to the benzene structure, restoring the reducing properties of diaminodiphenylamine. Therefore, in the subsequent chlorination process, diaminodiphenylamine can continue to react with active chlorine, thereby improving the chlorine resistance of the membrane, thereby achieving regenerable chlorine resistance of the reverse osmosis membrane.

[0082] The above describes in detail the method for preparing a high-throughput, regenerable, chlorine-resistant reverse osmosis composite membrane based on the surface modification of an aniline dimer provided by the present invention. The principles and implementation methods of the present invention are described herein. The examples described are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the basic principles of the present invention and in accordance with the technical essence of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for preparing a high-flux, regenerable, chlorine-resistant reverse osmosis composite membrane, characterized in that the high-flux, regenerable, chlorine-resistant reverse osmosis composite membrane is a diaminodiphenylamine-grafted reverse osmosis polyamide composite membrane, and the preparation method comprises the following steps: Step 1: Preparation of reverse osmosis polyamide composite membrane 1.1 Use polymer solution as casting solution, apply the casting solution on non-woven fabric, immerse it in a coagulation bath to form a support layer, and prepare a polymer base membrane; 1.2 Soak the polymer base film in sodium bisulfite solution for 30 minutes, then remove the polymer base film and rinse it with deionized water, then soak it in isopropyl alcohol solution for 30 minutes, and finally rinse it thoroughly with deionized water; 1.3 Immerse the polymer base film in the aqueous solution for 1-5 minutes, then remove the base film and remove excess water droplets on its surface with an air knife. Then, immerse it in the polyacyl chloride oil solution at room temperature for 1-5 minutes. 1.4 The polymer membrane obtained in step 1.3 is heat-treated at 35-75°C for 1-10 minutes, then washed with citric acid solution to remove residual substances on the membrane surface, then rinsed with deionized water for 1-10 minutes, and then immersed in a glycerol aqueous solution for 1-10 minutes for moisturizing treatment; 1.5 The membrane obtained in step 4) is heat-treated in an oven for 1-20 min to obtain a reverse osmosis polyamide composite membrane; Step 2 Preparation of diaminodiphenylamine grafted reverse osmosis polyamide composite membrane 2.1 Weigh diaminodiphenylamine, grind it thoroughly in a mortar and pestle, and dissolve it in ethanol to prepare a diaminodiphenylamine ethanol solution with a mass concentration of 1-10%. Ultrasonicate it for 5 minutes to fully dissolve it. 2.2 Weigh glutaraldehyde and fully dissolve it in pure water to prepare a glutaraldehyde aqueous solution with a mass concentration of 1-40%; 2.3 Pour the diaminodiphenylamine ethanol solution onto the surface of the reverse osmosis polyamide composite membrane, allowing the membrane surface to contact with the ethanol solution for 2 minutes at room temperature, then rinse the modified membrane surface with ethanol solution and deionized water several times, and soak it in deionized water to remove the residual modification solvent and ungrafted dimer on the membrane surface, and then store it in deionized water for later use; 2.4 Immerse the modified membrane in step 2.3 in a glutaraldehyde crosslinker solution for 1-20 minutes, and then heat-treat it in an oven at 60-80°C for 1-20 minutes; 2.5 The membrane prepared in step 2.4 is subjected to chlorination reaction and chlorination reduction post-treatment in sequence to obtain a diaminodiphenylamine grafted reverse osmosis polyamide composite membrane.

2. The method for preparing a high-flux regenerable chlorine-resistant reverse osmosis composite membrane according to claim 1, wherein: The polymer is at least one of polyethersulfone, polyacrylonitrile, bisphenol A polysulfone, polyvinylidene fluoride, and polyvinyl chloride.

3. The method for preparing a high-flux regenerable chlorine-resistant reverse osmosis composite membrane according to claim 1, wherein: The aqueous phase solution is composed of the following substances by mass fraction: 1.0-8.0 wt% of m-phenylenediamine, 0.05-2.0 wt% of 3,5-diamino-1,2,4-triazole, 1.0-7.0 wt% of camphorsulfonic acid, 1.0-4 wt% of triethylamine, 0.05-0.2 wt% of sodium hydroxide, and the balance is water.

4. The method for preparing a high-flux regenerable chlorine-resistant reverse osmosis composite membrane according to claim 1, wherein: The pH of the aqueous solution is 9-11.

5. The method for preparing a high-flux regenerable chlorine-resistant reverse osmosis composite membrane according to claim 1, wherein: The mass concentration of the polyacyl chloride in the polyacyl chloride oil phase solution is 0.05-0.5%, and the balance is organic solvent.

6. The method for preparing a high-flux regenerable chlorine-resistant reverse osmosis composite membrane according to claim 1, wherein: The polybasic acid chloride is one or more of trimesoyl chloride, terephthaloyl chloride, oxalyl chloride, etc.; the organic solvent is one or more of dichloromethane, n-hexane, ethylcyclohexane, toluene, xylene, m-xylene, mesitylene, isoparE, isoparG, isoparH, isoparM, etc.

7. The method for preparing a high-flux regenerable chlorine-resistant reverse osmosis composite membrane according to claim 1, characterized in that: The mass concentration of the citric acid solution is 12%, the washing time is 1-20 minutes, and the temperature is 50°C.

8. The method for preparing a high-flux regenerable chlorine-resistant reverse osmosis composite membrane according to claim 1, wherein: The chlorination reaction is to wash the membrane with deionized water and sodium hypochlorite solution in sequence, then immerse the membrane surface in sodium hypochlorite solution for chlorination, and then use deionized water to remove the active chlorine remaining on the membrane surface.

9. The method for preparing a high-flux regenerable chlorine-resistant reverse osmosis composite membrane according to claim 1, wherein: The chlorination reduction post-treatment is to first place the membrane in an active chlorine solution for treatment, and then place it in a Na2S2O3 solution for constant temperature oscillation reduction.

10. A high-flux, regenerable, chlorine-resistant reverse osmosis composite membrane prepared by the method for preparing a high-flux, regenerable, chlorine-resistant reverse osmosis composite membrane according to any one of claims 1 to 9.

Images