A reverse osmosis membrane and its preparation method

Abstract

The application relates to a reverse osmosis membrane and a preparation method thereof, which comprises the following steps: oscillating a polysulfone-based membrane in a mixed solution containing dopamine at a constant temperature to form a dopamine pretreatment layer, thereby obtaining a modified base membrane; dissolving rosmarinic acid ester modified m-phenylenediamine, piperazine, a surfactant, an additive, and a pH regulator in water, stirring and dissolving to obtain an aqueous phase solution; dissolving an acyl chloride monomer in an organic solvent, stirring and dissolving, then adding modified titanium dioxide and ultrasonic dispersing to obtain an oil phase solution; immersing the modified base membrane in the aqueous phase solution, taking out, then immersing in the oil phase solution, and taking out and drying to obtain a pre-composite reverse osmosis membrane; and post-treating the pre-composite reverse osmosis membrane to obtain the reverse osmosis membrane. The reverse osmosis membrane in the application has a high desalination rate and long-term improved oxidation resistance of the reverse osmosis membrane under the condition of ensuring water production.

Description

Technical Field

[0001] This application relates to the field of membrane separation technology, and in particular to a reverse osmosis membrane and a method for preparing the same. Background Technology

[0002] The core principle of reverse osmosis desalination technology is to utilize the selective retention of solutes in aqueous solutions by a reverse osmosis membrane. Driven by an external pressure difference higher than the osmotic pressure of the solution, water molecules permeate against the concentration gradient from the high-salt side to the low-salt side, thus achieving efficient separation of salt and water. The key to this technology lies in the separation performance of the reverse osmosis membrane. Its dense surface structure effectively blocks impurities such as inorganic salts, organic matter, and microorganisms while ensuring the smooth permeation of water molecules, giving it an irreplaceable position in the field of water treatment.

[0003] In practical applications, the stability of reverse osmosis membranes directly determines the economic efficiency and reliability of the technology. In industrial wastewater treatment, oxidants such as ozone and hydrogen peroxide, as well as active chlorine species generated during seawater desalination electrolysis, pose potential threats to the structure of reverse osmosis membranes. If the membrane material lacks sufficient oxidation resistance, its surface polymer chains are easily attacked by oxidants, leading to chemical bond breakage and cross-linking structure destruction. This results in a sharp decline in membrane retention performance, an abnormal increase in water flux, severely shortening the membrane's lifespan and increasing operating costs. Currently, most industrially widely used composite reverse osmosis membranes use polysulfone or polyethersulfone as the support layer, forming a polyamide desalination layer on its surface through interfacial polymerization. Polyamide materials have become the mainstream choice due to their high cross-linking density and excellent desalination performance; however, the amide bonds abundant in their molecular chains are sensitive to oxidants. Free chlorine can destroy the stability of the amide bonds through N-chloroation, leading to membrane structure degradation. To improve oxidation resistance, researchers enhanced molecular chain stability through the conjugation effect of aromatic heterocycles, which significantly improved oxidation resistance. However, due to the large steric hindrance of the heterocycle structure, it is difficult to form a dense cross-linked network, resulting in a generally low desalination rate, which cannot meet the requirements of scenarios with high desalination precision, such as seawater desalination.

[0004] Furthermore, while existing technologies that introduce antioxidant additives can delay membrane oxidative degradation to some extent, the interfacial bonding between the coating and the membrane substrate is weak, making it prone to erosion and detachment by water flow over long-term operation. The migration and loss of these additives also lead to a gradual decline in oxidation resistance. Simultaneously, these modification methods often increase membrane mass transfer resistance, resulting in a decrease in water flux. Therefore, developing a composite reverse osmosis membrane that can maintain a high desalination rate while tolerating long-term oxidative environments has become a critical issue that urgently needs to be addressed in the field of membrane separation technology. Summary of the Invention

[0005] In order to effectively improve the desalination performance and oxidation resistance of reverse osmosis membranes, this application provides a reverse osmosis membrane and a method for preparing the same.

[0006] The reverse osmosis membrane and its preparation method provided in this application adopt the following technical solution: A reverse osmosis membrane and its preparation method include the following steps: S1: Immersing a polysulfone-based membrane in a mixed solution containing dopamine and oscillating at a constant temperature to form a dopamine pretreatment layer, thereby obtaining a modified base membrane;

[0007] S2: Dissolve 2-5 wt% rosmarinic acid ester modified m-phenylenediamine, 1-3 wt% piperazine, 0.1-0.5 wt% surfactant, 5-8 wt% auxiliaries, and 1.5-3 wt% pH adjuster in the remaining water, stir to dissolve, and obtain an aqueous solution;

[0008] S3: Dissolve 0.1-0.4 wt% acyl chloride monomers in 98.3-99.1 wt% organic solvent, stir to dissolve, then add 0.8-1.5 wt% modified titanium dioxide, and ultrasonically disperse to obtain an oil phase solution;

[0009] S4: Immerse the modified base membrane in the aqueous solution, remove it, then immerse it in the oil solution, remove it and dry it to obtain a pre-composite reverse osmosis membrane;

[0010] S5: The pre-composite reverse osmosis membrane is post-processed to obtain the reverse osmosis membrane.

[0011] By employing the above technical solution, a polysulfone-based membrane is used as the supporting substrate and immersed in a mixed solution containing dopamine. Dopamine self-polymerizes to form a pretreatment layer rich in catechol groups. Catechol forms strong hydrogen bonds with the surface of the polysulfone-based membrane, which not only strengthens the bonding force between the polysulfone layer and the polyamide layer to resist interlayer delamination under high pressure, but also uniformly adsorbs aqueous monomers through active sites, forming the basis for interfacial polymerization. The aqueous solution uses rosmarinic acid ester modified m-phenylenediamine as the core. Its active amino groups can react with oil phase acyl chloride monomers to construct a polyamide skeleton. The introduced rosmarinic acid ester groups contain ortho-phenolic hydroxyl groups and conjugated esterified acrylic acid segments. The phenolic hydroxyl groups can capture oxidant free radicals (•OH, ClO•, etc.) through proton transfer, while the conjugated esterified acrylic acid segments add active oxygen through double bonds. These active groups are more likely to react preferentially with free chlorine on the surface of the polyamide layer, thereby protecting the amide bonds of the polyamide layer from oxidation by free chlorine and other substances, thus achieving the oxidation resistance of the reverse osmosis membrane and forming a long-term antioxidant basis.

[0012] Then, the diamino structure of piperazine synergistically participates in polymerization with modified m-phenylenediamine, increasing the crosslinking density of polyamide chains to reduce intermolecular gaps and enhance the retention capacity of salt ions. Surfactants and auxiliaries ensure sufficient interfacial polymerization between acyl chloride monomers and aqueous amines, constructing a dense separation layer structure. Modified titanium dioxide, after interfacial modification, is uniformly dispersed in the oil phase, enhancing the mechanical strength of the separation layer. Through modification, it can synergistically work with the rosmarinic acid ester groups in the aqueous phase to further scavenge reactive oxygen species and prevent microbial oxidation, strengthening the antioxidant network. This allows the aqueous and oil phases to cooperate in this process. The amine monomers in the aqueous phase and the acyl chloride monomers in the oil phase directionally polymerize on the surface of the pretreated layer, forming a uniform and dense polyamide separation layer. The rosmarinic acid ester groups and modified titanium dioxide have the function of chemically capturing and physically scavenging oxidant free radicals. The synergistic crosslinking of piperazine and acyl chloride can also improve the density of the polyamide layer to enhance the desalination rate. The pretreated layer ensures the overall structural stability. The reverse osmosis membrane of this application maintains high desalination performance while possessing excellent oxidation resistance, thus extending the service life of the reverse osmosis membrane and meeting practical application requirements.

[0013] In one specific feasible implementation, the method for preparing the modified titanium dioxide includes: dispersing titanium dioxide and graphene quantum dots in water, adding KH-570, stirring and reacting at 55-65℃ for 2-3 hours, centrifuging, washing, and drying to obtain modified titanium dioxide.

[0014] The mass ratio of titanium dioxide to graphene quantum dots is (7-10):1.

[0015] By employing the above technical solution, the siloxane groups of the silane coupling agent condense and bond with the hydroxyl groups on the surface of titanium dioxide, while the double bonds at the other end form π-π stacking with the conjugated structure of graphene quantum dots, thus firmly bonding titanium dioxide and graphene quantum dots. Through the chemical stability of titanium dioxide and the electron transfer capability of graphene quantum dots, reactive oxygen species are scavenged, jointly improving antioxidant performance, thereby reducing the oxidant content of the membrane and preventing degradation. In addition, titanium dioxide can also enhance the mechanical strength of the polyamide layer. The graphene quantum dots in graphene-modified titanium dioxide exhibit quantum size effects, and their surfaces are rich in hydroxyl and carboxyl groups. Through electron transfer, they can reduce reactive oxygen species (such as •OH, ClO•) to harmless water molecules or chloride ions, accelerating the electron transfer and quenching of reactive oxygen species. Furthermore, they achieve antioxidant interaction with the strong antioxidant phenolic hydroxyl groups of the aqueous rosmarinic acid ester group, extending the antioxidant lifespan of the membrane.

[0016] Therefore, excessively high graphene quantum dot content can lead to the aggregation of modified silica, which in turn forms localized dense areas in the oil phase. This disrupts the uniformity of the membrane structure, resulting in a decrease in desalination rate. Furthermore, the aggregation of quantum dots reduces electron transfer capacity, weakening the effective antioxidant interaction with rosmarinic acid ester groups and thus reducing antioxidant performance.

[0017] In one specific implementation scheme, the aqueous solution of rosmarinic acid ester-modified m-phenylenediamine is prepared by adding m-phenylenediamine and ethyl rosmarinic acid to ethanol, then adding concentrated sulfuric acid dropwise, refluxing at 60-65°C for 3-5 hours, cooling, and then distilling under reduced pressure to obtain rosmarinic acid ester-modified m-phenylenediamine.

[0018] Preferably, the mass ratio of m-phenylenediamine to ethyl rosmarinic acid is 1:(1.2-1.5).

[0019] By adopting the above technical solution, the introduction of rosmarinic acid ester antioxidant groups allows these groups to attach to the m-phenylenediamine molecular chain, thereby increasing the number of active groups such as phenolic hydroxyl groups and conjugated double bonds. During membrane use, these groups can continuously capture oxidant free radicals, increasing their stability after gaining electrons and protons, terminating their oxidation chain reaction, and thus inactivating oxidant free radicals. Because the benzene ring on the phenolic hydroxyl group, having lost its protons, has high conjugated stability, it will not cause degradation, thus greatly enhancing the membrane's antioxidant capacity and extending its oxidation resistance lifespan. Furthermore, the carbon atoms at both ends of the double bonds in the olefin segment combine with the oxygen atoms of active oxygen to form stable oxygen-containing heterocycles or chain compounds, thereby inactivating active oxygen. This can synergize with the phenolic hydroxyl groups, significantly improving the membrane's tolerance to chlorinated and oxygenated water bodies and enhancing the overall antioxidant performance of the reverse osmosis membrane. Therefore, if the content of ethyl rosmarinic acid is too high, the excessive ester groups will weaken the cross-linking density of the polyamide separation layer, making the separation layer structure loose, the water flux will increase accordingly, and the salt ion retention performance will decrease. If the content of rosmarinic acid ester groups is too low, the antioxidant sites will be scarce, and the membrane will be unable to effectively capture oxidant free radicals. The membrane's oxidation resistance will decrease, and the desalination rate will easily drop sharply in a short time in chlorinated water.

[0020] In the aqueous solution, the surfactant is one of sodium dodecyl sulfonate, sodium dodecylbenzene sulfonate, sodium lauryl sulfonate, and sodium glycocholate; the auxiliary agent is N-methylpyrrolidone; and the pH adjuster is sodium hydroxide.

[0021] In the oil phase solution, the acyl chloride monomer is one or both of pyromellitic tricarboxylic acid chloride and trifluoromethylbenzoyl chloride; the organic solvent is a methyl-substituted hydrocarbon with 5-12 carbon atoms.

[0022] Preferably, the mass ratio of pyromellitic trimethylbenzyl chloride to trifluoromethylbenzoyl chloride is 3:1.

[0023] By adopting the above technical solution, the fluorine atoms introduced by trifluoromethylbenzoyl chloride have strong electronegativity, which can reduce the intermolecular gaps through the inductive effect and enhance the chemical stability and oxidation resistance of the membrane. Sufficient crosslinking density is ensured by pyromellitic trichloromethylbenzoyl chloride, while an appropriate amount of fluorine atoms are introduced by trifluoromethylbenzoyl chloride to balance density and oxidation resistance. If the content of pyromellitic trichloromethylbenzoyl chloride is too high, excessive crosslinking reaction will make the separation layer too dense, drastically increasing the resistance to water molecule transport, significantly reducing water flux, and rendering it impractical. Conversely, if the content of trifluoromethylbenzoyl chloride is too high, the crosslinking network of the separation layer will be loose, weakening the salt ion retention capacity and reducing the desalination rate.

[0024] The post-treatment in S5 involves sequentially immersing the sample in a mixed aqueous solution of zirconium chloride (0.5-1% by mass), chitosan, and glutaraldehyde, followed by drying.

[0025] Preferably, in the chitosan and glutaraldehyde mixed aqueous solution, chitosan and glutaraldehyde account for 2-5% of the mixed aqueous solution; the mass ratio of chitosan to glutaraldehyde is 10:1.

[0026] By adopting the above technical solution, the post-treatment further enhances membrane performance. The pre-composite membrane is first immersed in a zirconium chloride aqueous solution. Zr4+, as a polyvalent metal ion, undergoes a coordination reaction with the nitrogen atoms of the amide bond and the phenolic hydroxyl groups of the rosmarinic acid ester group in the polyamide separation layer, forming a stable six-membered ring coordination structure. This further reduces intermolecular porosity to improve desalination rate and enhances the stability of the separation layer, extending the service life of the reverse osmosis membrane. Then, it is immersed in a mixture of chitosan and glutaraldehyde. The amino groups of chitosan react with the aldehyde groups of glutaraldehyde to construct a protective layer on the membrane surface, enhancing hydrophilicity while preventing pollutants and oxidants from directly contacting the separation layer. The chitosan and glutaraldehyde are mixed in the mass ratio specified in this application, ensuring that the glutaraldehyde fully crosslinks with the chitosan to form a stable protective layer. This layer, together with the antioxidant groups and dense structure of the polyamide layer, achieves long-term stability in desalination rate and oxidation resistance. Excessive glutaraldehyde content increases the density of the protective layer and reduces water flux; insufficient glutaraldehyde content results in inadequate cross-linking of the protective layer, a loose protective layer structure, easy adhesion of pollutants to the membrane surface, and easy penetration of oxidants into the separation layer, leading to aggravated membrane fouling and decreased oxidation resistance.

[0027] Secondly, this application provides a reverse osmosis membrane.

[0028] In summary, this application includes at least one of the following beneficial technical effects:

[0029] 1. This application ensures a stable bond between the base membrane and the functional layer through a dopamine pretreatment layer. The rosmarinic acid ester-modified m-phenylenediamine and modified titanium dioxide work together to greatly enhance the antioxidant performance of the reverse osmosis membrane. Piperazine and modified m-phenylenediamine increase the crosslinking density, and the dense structure formed by the acyl chloride monomer significantly improves the desalination rate. The post-treatment further fixes the configuration and pore size distribution of the functional groups, extending the performance stability. The reverse osmosis membrane of this application maintains high desalination performance while possessing excellent oxidation resistance, thereby extending the service life of the reverse osmosis membrane and meeting the needs of practical applications.

[0030] 2. Post-treatment further enhances membrane performance. The pre-composite membrane is first immersed in a zirconium chloride aqueous solution. Zr⁴⁺, as a polyvalent metal ion, undergoes a coordination reaction with the nitrogen atoms of the amide bonds and the phenolic hydroxyl groups of the rosmarinic acid ester groups in the polyamide separation layer, forming a stable six-membered ring coordination structure. This further reduces intermolecular porosity to improve desalination rate and enhances the stability of the separation layer, extending the service life of the reverse osmosis membrane. Next, it is immersed in a mixture of chitosan and glutaraldehyde. The amino groups of chitosan react with the aldehyde groups of glutaraldehyde to construct a protective layer on the membrane surface, enhancing hydrophilicity while preventing pollutants and oxidants from directly contacting the separation layer. The chitosan and glutaraldehyde are mixed in the mass ratio specified in this application, ensuring that glutaraldehyde fully crosslinks with chitosan to form a stable protective layer. This layer, together with the antioxidant groups and dense structure of the separation layer, achieves long-term stability in desalination rate and oxidation resistance. Detailed Implementation

[0031] Unless otherwise specified, all raw materials used in this application are from commercially available brands or obtained through conventional preparation processes. Specifically, the concentrated sulfuric acid is 98% concentrated sulfuric acid; rosmarinic acid ester is ethyl rosmarinic acid purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; graphene quantum dots, model XF237, are purchased from Xianfeng Nano; titanium dioxide is purchased from Aladdin, item number T301758; trifluoromethylbenzoyl chloride is p-trifluoromethylbenzoyl chloride purchased from Guangdong Yuanfeng Chemical Reagent Co., Ltd.; zirconium chloride aqueous solution: prepared as a 0.8% zirconium chloride aqueous solution; chitosan is purchased from Shanghai Yuanye.

[0032] Preparation of a mixed aqueous solution of chitosan and glutaraldehyde: Take a mixture of chitosan and glutaraldehyde and add water to prepare a 3% (w / w) mixed aqueous solution of chitosan and glutaraldehyde; wherein the mass ratio of chitosan to glutaraldehyde is 10:1.

[0033] Preparation of a mixed solution containing dopamine: A 2% (w / w) mixed solution of dopamine and triethylamine, wherein the mass ratio of dopamine to triethylamine is 5:1.

[0034] Preparation Example 1

[0035] Preparation of modified titanium dioxide: 10g of titanium dioxide and 1g of graphene quantum dots were dispersed in 200ml of water and magnetically stirred for 30min until uniformly dispersed. 0.22g of KH-570 was added and stirred at 65℃ for 3h. After centrifugation at 8000r / min for 10min, the precipitate was washed 3 times with water and 1 time with anhydrous ethanol. The precipitate was then vacuum dried at 60℃ for 12h to obtain modified titanium dioxide.

[0036] Preparation Example 2

[0037] Preparation of modified titanium dioxide: 8g of titanium dioxide and 3g of graphene quantum dots were dispersed in 200ml of water and magnetically stirred for 30min until uniformly dispersed. 0.22g of KH-570 was added and stirred at 65℃ for 3h. After centrifugation at 8000r / min for 10min, the precipitate was washed 3 times with water and 1 time with anhydrous ethanol. The precipitate was then vacuum dried at 60℃ for 12h to obtain modified titanium dioxide.

[0038] Preparation Example 3

[0039] Preparation of rosmarinic acid ester modified m-phenylenediamine: 3.24 g m-phenylenediamine and 3.96 g ethyl rosmarinic acid were added to 100 ml ethanol and magnetically stirred until completely dissolved. Then 0.08 g concentrated sulfuric acid was added dropwise, and the mixture was refluxed at 65 °C for 5 h. After natural cooling, the mixture was distilled under reduced pressure at 60 °C and -0.09 MPa, and dried under vacuum at 40 °C for 8 h to obtain rosmarinic acid ester modified m-phenylenediamine.

[0040] Preparation Example 4

[0041] Preparation of rosmarinic acid ester modified m-phenylenediamine: 2.7 g m-phenylenediamine and 4.5 g ethyl rosmarinic acid were added to 100 ml ethanol and magnetically stirred until completely dissolved. Then 0.08 g concentrated sulfuric acid was added dropwise, and the mixture was refluxed at 65 °C for 5 h. After natural cooling, the mixture was distilled under reduced pressure at 60 °C and -0.09 MPa, and dried under vacuum at 40 °C for 8 h to obtain rosmarinic acid ester modified m-phenylenediamine.

[0042] Preparation Example 5

[0043] Preparation of rosmarinic acid ester modified m-phenylenediamine: 3.6 g m-phenylenediamine and 3.6 g ethyl rosmarinic acid were added to 100 ml ethanol and magnetically stirred until completely dissolved. Then 0.08 g concentrated sulfuric acid was added dropwise, and the mixture was refluxed at 65 °C for 5 h. After natural cooling, the mixture was distilled under reduced pressure at 60 °C and -0.09 MPa, and dried under vacuum at 40 °C for 8 h to obtain rosmarinic acid ester modified m-phenylenediamine.

[0044] Example 1

[0045] A reverse osmosis membrane and its preparation method, comprising the following steps:

[0046] S1: Mix 17g polysulfone, 78g N,N-dimethylformamide and 4g polyoxyethylene ether, let stand, degas and filter to obtain casting solution; spray the casting solution evenly onto nonwoven fabric (100μm thickness, air permeability 2.5cc / cm2 / s) through a slit coating head and let stand for 10s, place in 15℃ water coagulation solution to obtain polysulfone-based membrane; immerse the polysulfone-based membrane in 2% dopamine and triethylamine mixed solution, and oscillate at 35℃ for 2h to form dopamine pretreatment layer to obtain modified base membrane;

[0047] S2: Dissolve 5g of rosmarinic acid ester modified m-phenylenediamine obtained in Preparation Example 3, 1g of piperazine, 0.5g of surfactant, 1.5g of sodium hydroxide and 5g of auxiliary agent in 87g of water, stir to dissolve, and obtain an aqueous solution;

[0048] S3: Dissolve 0.4g of acyl chloride monomer in 98.8g of isohexane, stir to dissolve, then add 0.8g of the modified titanium dioxide prepared in Example 1, and disperse by ultrasonication to obtain an oil phase solution; the acyl chloride monomer is pyromellitic trimethylbenzoyl chloride and trifluoromethylbenzoyl chloride in a mass ratio of 3:1;

[0049] S4: Immerse the modified base membrane in an aqueous solution for 6 seconds, remove it, then immerse it in an oil solution for 10 seconds, remove it and dry it at 60°C for 5 hours to obtain a pre-composite reverse osmosis membrane;

[0050] S5: The pre-composite reverse osmosis membrane is immersed in zirconium chloride aqueous solution for 30 min, rinsed with water, and then immersed in chitosan and glutaraldehyde mixed aqueous solution for 20 min. It is then dried at 60℃ for 2 h to obtain the reverse osmosis membrane.

[0051] Example 2

[0052] A reverse osmosis membrane and its preparation method, comprising the following steps:

[0053] S1: Mix 17g polysulfone, 78g N,N-dimethylformamide and 4g polyoxyethylene ether, let stand, degas and filter to obtain casting solution; spray the casting solution evenly onto nonwoven fabric (100μm thickness, air permeability 2.5cc / cm2 / s) through a slit coating head and let stand for 10s, place in 15℃ water coagulation solution to obtain polysulfone-based membrane; immerse the polysulfone-based membrane in 2% dopamine and triethylamine mixed solution, and oscillate at 35℃ for 2h to form dopamine pretreatment layer to obtain modified base membrane;

[0054] S2: Dissolve 3g of rosmarinic acid ester modified m-phenylenediamine obtained in Preparation Example 3, 3g of piperazine, 0.5g of surfactant, 1.5g of sodium hydroxide and 5g of additive in 87g of water, stir to dissolve, and obtain an aqueous solution;

[0055] S3: Dissolve 0.4g of acyl chloride monomer in 98.8g of isohexane, stir to dissolve, then add 0.8g of the modified titanium dioxide prepared in Example 1, and disperse by ultrasonication to obtain an oil phase solution; the acyl chloride monomer is pyromellitic trimethylbenzoyl chloride and trifluoromethylbenzoyl chloride in a mass ratio of 3:1;

[0056] S4: Immerse the modified base membrane in an aqueous solution for 6 seconds, remove it, then immerse it in an oil solution for 10 seconds, remove it and dry it at 60°C for 5 hours to obtain a pre-composite reverse osmosis membrane;

[0057] S5: The pre-composite reverse osmosis membrane is immersed in zirconium chloride aqueous solution for 30 min, rinsed with water, and then immersed in chitosan and glutaraldehyde mixed aqueous solution for 20 min. It is then dried at 60℃ for 2 h to obtain the reverse osmosis membrane.

[0058] Example 3

[0059] A reverse osmosis membrane and its preparation method, comprising the following steps:

[0060] S1: Mix 17g polysulfone, 78g N,N-dimethylformamide and 4g polyoxyethylene ether, let stand, degas and filter to obtain casting solution; spray the casting solution evenly onto nonwoven fabric (100μm thickness, air permeability 2.5cc / cm2 / s) through a slit coating head and let stand for 10s, place in 15℃ water coagulation solution to obtain polysulfone-based membrane; immerse the polysulfone-based membrane in 2% dopamine and triethylamine mixed solution, and oscillate at 35℃ for 2h to form dopamine pretreatment layer to obtain modified base membrane;

[0061] S2: Dissolve 5g of rosmarinic acid ester modified m-phenylenediamine obtained in Preparation Example 3, 1g of piperazine, 0.5g of surfactant, 1.5g of sodium hydroxide and 5g of auxiliary agent in 87g of water, stir to dissolve, and obtain an aqueous solution;

[0062] S3: Dissolve 0.4g of acyl chloride monomer in 98.8g of isohexane, stir to dissolve, then add 0.8g of modified titanium dioxide prepared in Example 2, and disperse by ultrasonication to obtain an oil phase solution; the acyl chloride monomer is pyromellitic trimethylbenzoyl chloride and trifluoromethylbenzoyl chloride in a mass ratio of 3:1.

[0063] S4: Immerse the modified base membrane in an aqueous solution for 6 seconds, remove it, then immerse it in an oil solution for 10 seconds, remove it and dry it at 60°C for 5 hours to obtain a pre-composite reverse osmosis membrane;

[0064] S5: The pre-composite reverse osmosis membrane is immersed in zirconium chloride aqueous solution for 30 min, rinsed with water, and then immersed in chitosan and glutaraldehyde mixed aqueous solution for 20 min. It is then dried at 60℃ for 2 h to obtain the reverse osmosis membrane.

[0065] Example 4

[0066] A reverse osmosis membrane and its preparation method, comprising the following steps:

[0067] S1: Mix 17g polysulfone, 78g N,N-dimethylformamide and 4g polyoxyethylene ether, let stand, degas and filter to obtain casting solution; spray the casting solution evenly onto nonwoven fabric (100μm thickness, air permeability 2.5cc / cm2 / s) through a slit coating head and let stand for 10s, place in 15℃ water coagulation solution to obtain polysulfone-based membrane; immerse the polysulfone-based membrane in 2% dopamine and triethylamine mixed solution, and oscillate at 35℃ for 2h to form dopamine pretreatment layer to obtain modified base membrane;

[0068] S2: Dissolve 5g of rosmarinic acid ester modified m-phenylenediamine obtained in Preparation Example 4, 1g of piperazine, 0.5g of surfactant, 1.5g of sodium hydroxide and 5g of auxiliary agent in 87g of water, stir to dissolve, and obtain an aqueous solution;

[0069] S3: Dissolve 0.4g of acyl chloride monomer in 98.8g of isohexane, stir to dissolve, then add 0.8g of the modified titanium dioxide prepared in Example 1, and disperse by ultrasonication to obtain an oil phase solution; the acyl chloride monomer is pyromellitic trimethylbenzoyl chloride and trifluoromethylbenzoyl chloride in a mass ratio of 3:1;

[0070] S4: Immerse the modified base membrane in an aqueous solution for 6 seconds, remove it, then immerse it in an oil solution for 10 seconds, remove it and dry it at 60°C for 5 hours to obtain a pre-composite reverse osmosis membrane;

[0071] S5: The pre-composite reverse osmosis membrane is immersed in zirconium chloride aqueous solution for 30 min, rinsed with water, and then immersed in chitosan and glutaraldehyde mixed aqueous solution for 20 min. It is then dried at 60℃ for 2 h to obtain the reverse osmosis membrane.

[0072] Example 5

[0073] A reverse osmosis membrane and its preparation method, comprising the following steps:

[0074] S1: Mix 17g polysulfone, 78g N,N-dimethylformamide and 4g polyoxyethylene ether, let stand, degas and filter to obtain casting solution; spray the casting solution evenly onto nonwoven fabric (100μm thickness, air permeability 2.5cc / cm2 / s) through a slit coating head and let stand for 10s, place in 15℃ water coagulation solution to obtain polysulfone-based membrane; immerse the polysulfone-based membrane in 2% dopamine and triethylamine mixed solution, and oscillate at 35℃ for 2h to form dopamine pretreatment layer to obtain modified base membrane;

[0075] S2: Dissolve 5g of rosmarinic acid ester modified m-phenylenediamine obtained in Preparation Example 5, 1g of piperazine, 0.5g of surfactant, 1.5g of sodium hydroxide and 5g of auxiliary agent in 87g of water, stir to dissolve, and obtain an aqueous solution;

[0076] S3: Dissolve 0.4g of acyl chloride monomer in 98.8g of isohexane, stir to dissolve, then add 0.8g of the modified titanium dioxide prepared in Example 1, and disperse by ultrasonication to obtain an oil phase solution; the acyl chloride monomer is pyromellitic trimethylbenzoyl chloride and trifluoromethylbenzoyl chloride in a mass ratio of 3:1;

[0077] S4: Immerse the modified base membrane in an aqueous solution for 6 seconds, remove it, then immerse it in an oil solution for 10 seconds, remove it and dry it at 60°C for 5 hours to obtain a pre-composite reverse osmosis membrane;

[0078] S5: The pre-composite reverse osmosis membrane is immersed in zirconium chloride aqueous solution for 30 min, rinsed with water, and then immersed in chitosan and glutaraldehyde mixed aqueous solution for 20 min. It is then dried at 60℃ for 2 h to obtain the reverse osmosis membrane.

[0079] Example 6

[0080] A reverse osmosis membrane and its preparation method, comprising the following steps:

[0081] S1: Mix 17g polysulfone, 78g N,N-dimethylformamide and 4g polyoxyethylene ether, let stand, degas and filter to obtain casting solution; spray the casting solution evenly onto nonwoven fabric (100μm thickness, air permeability 2.5cc / cm2 / s) through a slit coating head and let stand for 10s, place in 15℃ water coagulation solution to obtain polysulfone-based membrane; immerse the polysulfone-based membrane in 2% dopamine and triethylamine mixed solution, and oscillate at 35℃ for 2h to form dopamine pretreatment layer to obtain modified base membrane;

[0082] S2: Dissolve 5g of rosmarinic acid ester modified m-phenylenediamine obtained in Preparation Example 3, 1g of piperazine, 0.5g of surfactant, 1.5g of sodium hydroxide and 5g of auxiliary agent in 87g of water, stir to dissolve, and obtain an aqueous solution;

[0083] S3: Dissolve 0.4g of acyl chloride monomer in 98.8g of isohexane, stir to dissolve, then add 0.8g of modified titanium dioxide prepared in Example 1, and disperse by ultrasonication to obtain an oil phase solution; the acyl chloride monomer is pyromellitic trimethylbenzoyl chloride and trifluoromethylbenzoyl chloride in a mass ratio of 1:1;

[0084] S4: Immerse the modified base membrane in an aqueous solution for 6 seconds, remove it, then immerse it in an oil solution for 10 seconds, remove it and dry it at 60°C for 5 hours to obtain a pre-composite reverse osmosis membrane;

[0085] S5: The pre-composite reverse osmosis membrane is immersed in zirconium chloride aqueous solution for 30 min, rinsed with water, and then immersed in chitosan and glutaraldehyde mixed aqueous solution for 20 min. It is then dried at 60℃ for 2 h to obtain the reverse osmosis membrane.

[0086] Example 7

[0087] A reverse osmosis membrane and its preparation method, comprising the following steps:

[0088] S1: Mix 17g polysulfone, 78g N,N-dimethylformamide and 4g polyoxyethylene ether, let stand, degas and filter to obtain casting solution; spray the casting solution evenly onto nonwoven fabric (100μm thickness, air permeability 2.5cc / cm2 / s) through a slit coating head and let stand for 10s, place in 15℃ water coagulation solution to obtain polysulfone-based membrane; immerse the polysulfone-based membrane in 2% dopamine and triethylamine mixed solution, and oscillate at 35℃ for 2h to form dopamine pretreatment layer to obtain modified base membrane;

[0089] S2: Dissolve 5g of rosmarinic acid ester modified m-phenylenediamine obtained in Preparation Example 3, 1g of piperazine, 0.5g of surfactant, 1.5g of sodium hydroxide and 5g of auxiliary agent in 87g of water, stir to dissolve, and obtain an aqueous solution;

[0090] S3: Dissolve 0.4g of acyl chloride monomer in 98.8g of isohexane, stir to dissolve, then add 0.8g of modified titanium dioxide prepared in Example 1, and disperse by ultrasonication to obtain an oil phase solution; the acyl chloride monomer is trimesoyl chloride;

[0091] S4: Immerse the modified base membrane in an aqueous solution for 6 seconds, remove it, then immerse it in an oil solution for 10 seconds, remove it and dry it at 60°C for 5 hours to obtain a pre-composite reverse osmosis membrane;

[0092] S5: The pre-composite reverse osmosis membrane is immersed in zirconium chloride aqueous solution for 30 min, rinsed with water, and then immersed in chitosan and glutaraldehyde mixed aqueous solution for 20 min. It is then dried at 60℃ for 2 h to obtain the reverse osmosis membrane.

[0093] Example 8

[0094] A reverse osmosis membrane and its preparation method, comprising the following steps:

[0095] S1: Mix 17g polysulfone, 78g N,N-dimethylformamide and 4g polyoxyethylene ether, let stand, degas and filter to obtain casting solution; spray the casting solution evenly onto nonwoven fabric (100μm thickness, air permeability 2.5cc / cm2 / s) through a slit coating head and let stand for 10s, place in 15℃ water coagulation solution to obtain polysulfone-based membrane; immerse the polysulfone-based membrane in 2% dopamine and triethylamine mixed solution, and oscillate at 35℃ for 2h to form dopamine pretreatment layer to obtain modified base membrane;

[0096] S2: Dissolve 5g of rosmarinic acid ester modified m-phenylenediamine obtained in Preparation Example 3, 1g of piperazine, 0.5g of surfactant, 1.5g of sodium hydroxide and 5g of auxiliary agent in 87g of water, stir to dissolve, and obtain an aqueous solution;

[0097] S3: Dissolve 0.4g of acyl chloride monomer in 98.8g of isohexane, stir to dissolve, then add 0.8g of the modified titanium dioxide prepared in Example 1, and disperse by ultrasonication to obtain an oil phase solution; the acyl chloride monomer is pyromellitic trimethylbenzoyl chloride and trifluoromethylbenzoyl chloride in a mass ratio of 3:1;

[0098] S4: Immerse the modified base membrane in an aqueous solution for 6 seconds, remove it, then immerse it in an oil solution for 10 seconds, remove it and dry it at 60°C for 5 hours to obtain a pre-composite reverse osmosis membrane;

[0099] S5: Immerse the pre-composite reverse osmosis membrane sequentially in a zirconium chloride aqueous solution for 30 min, rinse with water, and then immerse it in a 3% (by mass) chitosan and glutaraldehyde mixed aqueous solution for 20 min (the mass ratio of chitosan to glutaraldehyde is 7:4). Dry it at 60℃ for 2 h to obtain the reverse osmosis membrane.

[0100] Example 9

[0101] A reverse osmosis membrane and its preparation method, comprising the following steps:

[0102] S1: Mix 17g polysulfone, 78g N,N-dimethylformamide and 4g polyoxyethylene ether, let stand, degas and filter to obtain casting solution; spray the casting solution evenly onto nonwoven fabric (100μm thickness, air permeability 2.5cc / cm2 / s) through a slit coating head and let stand for 10s, place in 15℃ water coagulation solution to obtain polysulfone-based membrane; immerse the polysulfone-based membrane in 2% dopamine and triethylamine mixed solution, and oscillate at 35℃ for 2h to form dopamine pretreatment layer to obtain modified base membrane;

[0103] S2: Dissolve 5g of rosmarinic acid ester modified m-phenylenediamine obtained in Preparation Example 3, 1g of piperazine, 0.5g of surfactant, 1.5g of sodium hydroxide and 5g of auxiliary agent in 87g of water, stir to dissolve, and obtain an aqueous solution;

[0104] S3: Dissolve 0.4g of acyl chloride monomer in 98.8g of isohexane, stir to dissolve, then add 0.8g of the modified titanium dioxide prepared in Example 1, and disperse by ultrasonication to obtain an oil phase solution; the acyl chloride monomer is pyromellitic trimethylbenzoyl chloride and trifluoromethylbenzoyl chloride in a mass ratio of 3:1;

[0105] S4: Immerse the modified base membrane in an aqueous solution for 6 seconds, remove it, then immerse it in an oil solution for 10 seconds, remove it and dry it at 60°C for 5 hours to obtain a pre-composite reverse osmosis membrane;

[0106] S5: Immerse the pre-composite reverse osmosis membrane sequentially in a zirconium chloride aqueous solution for 30 min, rinse with water, and dry at 60°C for 2 h to obtain the reverse osmosis membrane.

[0107] Example 10

[0108] A reverse osmosis membrane and its preparation method, comprising the following steps:

[0109] S1: Mix 17g polysulfone, 78g N,N-dimethylformamide and 4g polyoxyethylene ether, let stand, degas and filter to obtain casting solution; spray the casting solution evenly onto nonwoven fabric (100μm thickness, air permeability 2.5cc / cm2 / s) through a slit coating head and let stand for 10s, place in 15℃ water coagulation solution to obtain polysulfone-based membrane; immerse the polysulfone-based membrane in 2% dopamine and triethylamine mixed solution, and oscillate at 35℃ for 2h to form dopamine pretreatment layer to obtain modified base membrane;

[0110] S2: Dissolve 5g of rosmarinic acid ester modified m-phenylenediamine obtained in Preparation Example 3, 1g of piperazine, 0.5g of surfactant, 1.5g of sodium hydroxide and 5g of auxiliary agent in 87g of water, stir to dissolve, and obtain an aqueous solution;

[0111] S3: Dissolve 0.4g of acyl chloride monomer in 98.8g of isohexane, stir to dissolve, then add 0.8g of the modified titanium dioxide prepared in Example 1, and disperse by ultrasonication to obtain an oil phase solution; the acyl chloride monomer is pyromellitic trimethylbenzoyl chloride and trifluoromethylbenzoyl chloride in a mass ratio of 3:1;

[0112] S4: Immerse the modified base membrane in an aqueous solution for 6 seconds, remove it, then immerse it in an oil solution for 10 seconds, remove it and dry it at 60°C for 5 hours to obtain a pre-composite reverse osmosis membrane;

[0113] S5: Immerse the pre-composite reverse osmosis membrane sequentially in a mixed aqueous solution of chitosan and glutaraldehyde for 20 min, and dry it at 60℃ for 2 h to obtain the reverse osmosis membrane.

[0114] Comparative Example 1

[0115] A reverse osmosis membrane and its preparation method, comprising the following steps:

[0116] S1: Mix 17g polysulfone, 78g N,N-dimethylformamide and 4g polyoxyethylene ether, let stand, degas and filter to obtain casting solution; spray the casting solution evenly onto nonwoven fabric (100μm thickness, air permeability 2.5cc / cm2 / s) through a slit coating head and let stand for 10s, place in 15℃ water coagulation solution to obtain polysulfone-based membrane; immerse the polysulfone-based membrane in 2% dopamine and triethylamine mixed solution, and oscillate at 35℃ for 2h to form dopamine pretreatment layer to obtain modified base membrane;

[0117] S2: Dissolve 5g m-phenylenediamine, 1g piperazine, 0.5g surfactant, 1.5g sodium hydroxide and 5g additive in 87g water, stir to dissolve, and obtain an aqueous solution;

[0118] S3: Dissolve 0.4g of acyl chloride monomer in 98.8g of isohexane, stir to dissolve, then add 0.8g of the modified titanium dioxide prepared in Example 1, and disperse by ultrasonication to obtain an oil phase solution; the acyl chloride monomer is pyromellitic trimethylbenzoyl chloride and trifluoromethylbenzoyl chloride in a mass ratio of 3:1;

[0119] S4: Immerse the modified base membrane in an aqueous solution for 6 seconds, remove it, then immerse it in an oil solution for 10 seconds, remove it and dry it at 60°C for 5 hours to obtain a pre-composite reverse osmosis membrane;

[0120] S5: The pre-composite reverse osmosis membrane is immersed in zirconium chloride aqueous solution for 30 min, rinsed with water, and then immersed in chitosan and glutaraldehyde mixed aqueous solution for 20 min. It is then dried at 60℃ for 2 h to obtain the reverse osmosis membrane.

[0121] Comparative Example 2

[0122] A reverse osmosis membrane and its preparation method, comprising the following steps:

[0123] S1: Mix 17g polysulfone, 78g N,N-dimethylformamide and 4g polyoxyethylene ether, let stand, degas and filter to obtain casting solution; spray the casting solution evenly onto nonwoven fabric (100μm thickness, air permeability 2.5cc / cm2 / s) through a slit coating head and let stand for 10s, then place in a 15℃ water coagulation solution to obtain polysulfone-based film.

[0124] S2: Dissolve 5g of rosmarinic acid ester modified m-phenylenediamine obtained in Preparation Example 3, 1g of piperazine, 0.5g of surfactant, 1.5g of sodium hydroxide and 5g of auxiliary agent in 87g of water, stir to dissolve, and obtain an aqueous solution;

[0125] S3: Dissolve 0.4g of acyl chloride monomer in 98.8g of isohexane, stir to dissolve, then add 0.8g of the modified titanium dioxide prepared in Example 1, and disperse by ultrasonication to obtain an oil phase solution; the acyl chloride monomer is pyromellitic trimethylbenzoyl chloride and trifluoromethylbenzoyl chloride in a mass ratio of 3:1;

[0126] S4: Immerse the modified base membrane in an aqueous solution for 6 seconds, remove it, then immerse it in an oil solution for 10 seconds, remove it and dry it at 60°C for 5 hours to obtain a pre-composite reverse osmosis membrane;

[0127] S5: The pre-composite reverse osmosis membrane is immersed in zirconium chloride aqueous solution for 30 min, rinsed with water, and then immersed in chitosan and glutaraldehyde mixed aqueous solution for 20 min. It is then dried at 60℃ for 2 h to obtain the reverse osmosis membrane.

[0128] Comparative Example 3

[0129] A reverse osmosis membrane and its preparation method, comprising the following steps:

[0130] S1: Mix 17g polysulfone, 78g N,N-dimethylformamide and 4g polyoxyethylene ether, let stand, degas and filter to obtain casting solution; spray the casting solution evenly onto nonwoven fabric (100μm thickness, air permeability 2.5cc / cm2 / s) through a slit coating head and let stand for 10s, place in 15℃ water coagulation solution to obtain polysulfone-based membrane; immerse the polysulfone-based membrane in 2% dopamine and triethylamine mixed solution, and oscillate at 35℃ for 2h to form dopamine pretreatment layer to obtain modified base membrane;

[0131] S2: Dissolve 6g of rosmarinic acid ester modified m-phenylenediamine obtained in Preparation Example 3, 0.5g of surfactant, 1.5g of sodium hydroxide and 5g of auxiliary agent in 87g of water, stir to dissolve, and obtain an aqueous solution;

[0132] S3: Dissolve 0.4g of acyl chloride monomer in 98.8g of isohexane, stir to dissolve, then add 0.8g of the modified titanium dioxide prepared in Example 1, and disperse by ultrasonication to obtain an oil phase solution; the acyl chloride monomer is pyromellitic trimethylbenzoyl chloride and trifluoromethylbenzoyl chloride in a mass ratio of 3:1;

[0133] S4: Immerse the modified base membrane in an aqueous solution for 6 seconds, remove it, then immerse it in an oil solution for 10 seconds, remove it and dry it at 60°C for 5 hours to obtain a pre-composite reverse osmosis membrane;

[0134] S5: The pre-composite reverse osmosis membrane is immersed in zirconium chloride aqueous solution for 30 min, rinsed with water, and then immersed in chitosan and glutaraldehyde mixed aqueous solution for 20 min. It is then dried at 60℃ for 2 h to obtain the reverse osmosis membrane.

[0135] Comparative Example 4

[0136] A reverse osmosis membrane and its preparation method, comprising the following steps:

[0137] S1: Mix 17g polysulfone, 78g N,N-dimethylformamide and 4g polyoxyethylene ether, let stand, degas and filter to obtain casting solution; spray the casting solution evenly onto nonwoven fabric (100μm thickness, air permeability 2.5cc / cm2 / s) through a slit coating head and let stand for 10s, place in 15℃ water coagulation solution to obtain polysulfone-based membrane; immerse the polysulfone-based membrane in 2% dopamine and triethylamine mixed solution, and oscillate at 35℃ for 2h to form dopamine pretreatment layer to obtain modified base membrane;

[0138] S2: Dissolve 5g of rosmarinic acid ester modified m-phenylenediamine obtained in Preparation Example 3, 1g of piperazine, 0.5g of surfactant, 1.5g of sodium hydroxide and 5g of auxiliary agent in 87g of water, stir to dissolve, and obtain an aqueous solution;

[0139] S3: Dissolve 0.4g of acyl chloride monomer in 98.8g of isohexane, stir to dissolve, then add 0.8g of titanium dioxide, and disperse by ultrasonication to obtain an oil phase solution; the acyl chloride monomer is pyromellitic trimethylbenzoyl chloride and trifluoromethylbenzoyl chloride in a mass ratio of 3:1;

[0140] S4: Immerse the modified base membrane in an aqueous solution for 6 seconds, remove it, then immerse it in an oil solution for 10 seconds, remove it and dry it at 60°C for 5 hours to obtain a pre-composite reverse osmosis membrane;

[0141] S5: The pre-composite reverse osmosis membrane is immersed in zirconium chloride aqueous solution for 30 min, rinsed with water, and then immersed in chitosan and glutaraldehyde mixed aqueous solution for 20 min. It is then dried at 60℃ for 2 h to obtain the reverse osmosis membrane.

[0142] Comparative Example 5

[0143] A reverse osmosis membrane and its preparation method, comprising the following steps:

[0144] S1: Mix 17g polysulfone, 78g N,N-dimethylformamide and 4g polyoxyethylene ether, let stand, degas and filter to obtain casting solution; spray the casting solution evenly onto nonwoven fabric (100μm thickness, air permeability 2.5cc / cm2 / s) through a slit coating head and let stand for 10s, place in 15℃ water coagulation solution to obtain polysulfone-based membrane; immerse the polysulfone-based membrane in 2% dopamine and triethylamine mixed solution, and oscillate at 35℃ for 2h to form dopamine pretreatment layer to obtain modified base membrane;

[0145] S2: Dissolve 5g of rosmarinic acid ester modified m-phenylenediamine obtained in Preparation Example 3, 1g of piperazine, 0.5g of surfactant, 1.5g of sodium hydroxide and 5g of auxiliary agent in 87g of water, stir to dissolve, and obtain an aqueous solution;

[0146] S3: Dissolve 0.4g of acyl chloride monomer in 98.8g of isohexane, stir to dissolve, then add 0.8g of the modified titanium dioxide prepared in Example 1, and disperse by ultrasonication to obtain an oil phase solution; the acyl chloride monomer is pyromellitic trimethylbenzoyl chloride and trifluoromethylbenzoyl chloride in a mass ratio of 3:1;

[0147] S4: Immerse the modified base membrane in the aqueous phase solution for 6 seconds, remove it, then immerse it in the oil phase solution for 10 seconds, remove it and dry it at 60°C for 5 hours to obtain the reverse osmosis membrane.

[0148] Performance testing

[0149] Chlorine oxidation performance tests were conducted on the reverse osmosis membranes prepared in Examples 1-10 and Comparative Examples 1-5:

[0150] Test solution: 2000 ppm NaCl solution, pH 7.5, temperature 25℃, pressure 1.55 MPa;

[0151] Prepare a 1000ppm sodium hypochlorite solution with a pH of 5 as the oxidizing solution for the detection experiment;

[0152] The reverse osmosis membrane was soaked for 60 minutes. After removal, it was rinsed with pure water for 30 minutes to remove the protective solution, and then soaked in pure water for 24 hours to equilibrate. The water flux and salt rejection performance of the reverse osmosis membrane were measured initially and after soaking in the oxidation solution. The results are shown in Table 1.

[0153] Table 1 Performance Test Results

[0154]

[0155] As can be seen from Examples 1-10 of the present invention, the water flux and rejection rate of the high-flux reverse osmosis membrane obtained by the present invention before and after chlorination, compared with Comparative Examples 1-5, have high rejection rate and oxidation resistance while maintaining water flux.

[0156] As can be seen from Examples 1-5 and Comparative Examples 1-4 of this application, the present invention introduces rosmarinic acid ester groups into the polyamide molecular chain of the separation layer by modifying m-phenylenediamine with rosmarinic acid ester. The ester groups in the molecule form hydrogen bonds with the phenolic hydroxyl groups of the dopamine pretreated layer, enhancing the bonding force between the substrate and the separation layer. The multi-coordinate structure formed by zirconium ions and the phenolic hydroxyl and carboxyl groups of rosmarinic acid ester not only strengthens the stability of the antioxidant groups but also improves the mechanical strength of the membrane, achieving a synergistic enhancement of oxidation resistance, desalination rate, and mechanical properties. Rosmarinic acid ester can efficiently capture free radicals generated by oxidants such as free chlorine through multi-site proton transfer, forming a stable conjugated structure, thereby blocking the attack of oxidation reactions on the polyamide backbone and effectively protecting the separation performance of the polyamide layer. At the same time, rosmarinic acid ester has antibacterial properties, preventing microbial oxidation and degradation of the reverse osmosis membrane in water, and can reduce the probability of contact between oxidants and polyamide molecules. It forms a dual antioxidant system with graphene quantum dot modified titanium dioxide, significantly improving the oxidation resistance life of the membrane.

[0157] Comparative Examples 8-10 and Comparative Example 5 show that Zr⁴⁺, as a polyvalent metal ion, undergoes coordination reactions with the nitrogen atoms of the amide bonds and the phenolic hydroxyl groups of the rosmarinic acid ester groups in the polyamide separation layer, forming a stable six-membered ring coordination structure. This further reduces intermolecular porosity to improve desalination rate, enhances the stability of the separation layer, and extends the service life of the reverse osmosis membrane. Upon re-immersion in a mixture of chitosan and glutaraldehyde, the amino groups of chitosan react with the aldehyde groups of glutaraldehyde, constructing a protective layer on the membrane surface. This enhances hydrophilicity while preventing contaminants and oxidants from directly contacting the separation layer.

[0158] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A method for producing a reverse osmosis membrane, characterized by, The method comprises the following steps: S1: immerse a polysulfone-based membrane into a mixed solution containing dopamine, and oscillate at a constant temperature to form a dopamine pretreatment layer, thereby obtaining a modified base membrane; S2: dissolve 2-5 wt% rosmarinic acid ester-modified m-phenylenediamine, 1-3 wt% piperazine, 0.1-0.5 wt% surfactant, and 5-8 wt% auxiliary agent, and 1.5-3 wt% pH regulator in the remaining amount of water, and stir to dissolve, thereby obtaining an aqueous phase solution; S3: dissolve 0.1-0.4 wt% acyl chloride monomer in 98.3-99.1 wt% organic solvent, stir to dissolve, then add 0.8-1.5 wt% modified titanium dioxide, and ultrasonically disperse, thereby obtaining an oil phase solution; S4: immerse the modified base membrane into the aqueous phase solution, take it out, immerse it into the oil phase solution again, and then dry after taking it out, thereby obtaining a pre-composite reverse osmosis membrane; S5: perform post-treatment on the pre-composite reverse osmosis membrane, thereby obtaining the reverse osmosis membrane; In the aqueous phase solution, the preparation method of the rosmarinic acid ester-modified m-phenylenediamine comprises the following steps: taking m-phenylenediamine and rosmarinic acid ethyl ester, adding them into ethanol, then adding concentrated sulfuric acid dropwise, refluxing at 60-65 ℃ for 3-5 h, and then cooling and distilling under reduced pressure, thereby obtaining the rosmarinic acid ester-modified m-phenylenediamine.

2. The method of claim 1, wherein the reverse osmosis membrane is prepared by the steps of: The preparation method of the modified titanium dioxide comprises the following steps: taking titanium dioxide and graphene quantum dots, dispersing them in water, adding KH-570, stirring at 55-65 ℃ for 2-3 h, centrifuging, washing, and drying, thereby obtaining the modified titanium dioxide.

3. The method of claim 2, wherein the polyamide is prepared by the reaction of a diamine and a diacid. The mass ratio of the titanium dioxide to the graphene quantum dots is (7-10):

1.

4. The method of claim 1, wherein the reverse osmosis membrane is prepared by the steps of: In the aqueous phase solution, the surfactant is one of sodium dodecyl sulfonate, sodium dodecyl benzene sulfonate, sodium lauryl sulfonate, and sodium glycocholate; the auxiliary agent is N-methyl pyrrolidone; and the pH regulator is sodium hydroxide.

5. The method of claim 1, wherein the reverse osmosis membrane is prepared by the steps of: In the oil phase solution, the acyl chloride monomer is one or both of trimesoyl chloride and trifluoromethyl benzoyl chloride; and the organic solvent is a methyl-substituted hydrocarbon with 5-12 carbon atoms.

6. The method of claim 1, wherein the reverse osmosis membrane is prepared by the steps of: The post-treatment in S5 is to sequentially immerse into a 0.5-1% zirconium chloride aqueous solution, a chitosan and glutaraldehyde mixed aqueous solution, and then dry.

7. A reverse osmosis membrane, characterized by, The reverse osmosis membrane is prepared according to the method of any one of claims 1-6.

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