Seawater desalination reverse osmosis membrane and preparation method thereof

Abstract

The invention relates to the technical field of water treatment, and particularly discloses a seawater desalination reverse osmosis membrane and a preparation method thereof. The sea water desalination reverse osmosis membrane comprises a base membrane layer and a separation layer, the base membrane layer comprises a base layer and a porous support layer, and the sea water desalination reverse osmosis membrane is characterized in that the separation layer comprises the following raw materials in parts by weight: 15-20 parts of bis-2-6-N, N-dimethyl formamide, 1-5 parts of sodium hydroxide and 1-5 parts of sodium hydroxide; the environment-friendly anti-corrosion coating is prepared from the following components in parts by weight: 20 to 30 parts of N, N-(2-ethoxyl) diaminotoluene, 10 to 15 parts of triethylamine, 20 to 30 parts of camphorsulfonic acid, 10 to 15 parts of trifluoroacetic anhydride, 0.5 to 1.5 parts of sodium dodecyl sulfate, 10.5 to 20.5 parts of modified microcapsules, 0.5 to 1.5 parts of trimesoyl chloride and 150 to 180 parts of isoparaffin solvent. The reverse osmosis membrane for seawater desalination can be used in the field of seawater desalination, and has the advantages of high chemical stability, large water flux and excellent durability.

Description

Technical Field

[0001] The present application relates to the field of water treatment technology, and more specifically, to a seawater desalination reverse osmosis membrane and a preparation method thereof. Background Art

[0002] Desalination and recycling of seawater is an effective way to increase freshwater resources. Currently, the development of reverse osmosis membrane separation technology has become an important breakthrough in solving water shortages. The core component of reverse osmosis separation technology is the reverse osmosis membrane, which is one of the most widely used and best-performing separation membranes in the separation membrane field.

[0003] Reverse osmosis (RO) is often referred to as a pressure-driven water purification membrane process. It is one of the most advanced water treatment technologies today. The reverse osmosis membrane is the core component of the reverse osmosis process. It is a technology that uses a semipermeable membrane to separate solvents and solutes in a solution under pressure. The quality of its performance directly affects the overall efficiency and effluent quality of the water treatment system. The basic principle of the reverse osmosis membrane is that under a pressure higher than the osmotic pressure, water molecules in seawater pass through the semipermeable membrane, while most solutes such as ions and organic matter are retained on one side of the membrane. The filtration performance of the reverse osmosis membrane mainly depends on the chemical properties and physical structure of the membrane material. An ideal reverse osmosis membrane should have high water flux, high desalination rate, good mechanical strength and chemical stability.

[0004] At present, most of the reverse osmosis membranes on the market are polyamide composite membranes (TFC-PA), which are favored for their high water flux and salt rejection rate. In view of the above-mentioned related technologies, the inventors found that conventional reverse osmosis membranes contain a large number of amide groups, which have poor oxidation resistance and are prone to irreversible chemical changes and degradation when in contact with oxidants, resulting in the degradation of the reverse osmosis membrane. When used in special scenarios, there are problems such as short service life, and membrane performance such as water flux and desalination rate are easily affected, which in turn increases the cost of seawater desalination and reuse, affecting the final reverse osmosis effect.

[0005] Therefore, developing a seawater desalination reverse osmosis membrane with good oxidation resistance and durability is of great significance to improving the stability and economy of the reverse osmosis system. Summary of the invention

[0006] In order to improve the oxidation resistance of a reverse osmosis membrane and extend the service life of the reverse osmosis membrane, the present application provides a seawater desalination reverse osmosis membrane and a preparation method thereof.

[0007] In the first aspect, the present application provides a seawater desalination reverse osmosis membrane, which adopts the following technical solution: A seawater desalination reverse osmosis membrane comprises a base membrane layer and a separation layer, wherein the base membrane layer comprises a substrate layer and a porous support layer, and is characterized in that the raw materials of the separation layer comprise bis-2-6-N,N-(2-hydroxyethyl)diaminotoluene, triethylamine, camphorsulfonic acid, trifluoroacetic anhydride, sodium dodecylsulfonate, modified microcapsules, trimesoyl chloride and isoparaffin solvents.

[0008] By adopting the above technical solution, using bis-2-6-N, N-(2-hydroxyethyl) diaminotoluene to replace the raw materials such as m-phenylenediamine and triethylamine to prepare a polyamide composite membrane, it is helpful to form a more uniform and dense separation layer, which can improve the filtration efficiency and chemical stability of the reverse osmosis membrane and extend the durability of the reverse osmosis membrane. Since one hydrogen atom on the amino group of bis-2-6-N, N-(2-hydroxyethyl) diaminotoluene is replaced by a hydroxyethyl group, an amino group with two 2-hydroxyethyl substitutions is formed, and the activity is reduced, which greatly reduces the possibility of amide bond oxidation degradation, and plays a role in protecting the amide bond. Furthermore, the methyl group on the benzene ring of bis-2-6-N, N-(2-hydroxyethyl) diaminotoluene will increase the steric hindrance, hinder the oxidizing substance from approaching the reaction center, and can also reduce the possibility of amide bond oxidation degradation, and play a role in protecting the amide bond. In addition, the hydroxyethyl side chain of bis-2-6-N, N-(2-hydroxyethyl)diaminotoluene can enhance the hydrogen bonding between molecules, improve the interaction between polyamide chains, help reduce defects in the polymer chain, and improve the overall chemical stability of the polyamide membrane. The hydroxyl groups on the amine monomers can also undergo esterification reactions with acyl chloride groups to increase the cross-linking degree of the reverse osmosis membrane, effectively improve the oxidation resistance of the composite membrane, and extend the service life of the reverse osmosis membrane.

[0009] The use of trifluoroacetic anhydride introduces a strong electron-withdrawing group -CF3 as a protective group in the separation layer. The electron-withdrawing effect of -CF3 can reduce the electron cloud density on the amide bond and the aromatic ring, thereby reducing the reactivity of the amide bond. Active chlorine will first react with the protective group, effectively preventing the chlorination of the amide bond. In addition, due to the large size of the fluorine-containing group, the steric hindrance of the aromatic polyamide is increased, thereby improving the antioxidant properties of the polyamide composite membrane.

[0010] Optionally, the raw materials of the separation layer include, by weight, 15-20 parts of bis-2-6-N,N-(2-hydroxyethyl)diaminotoluene, 10-15 parts of triethylamine, 20-30 parts of camphorsulfonic acid, 10-15 parts of trifluoroacetic anhydride, 0.5-1.5 parts of sodium dodecyl sulfate, 10.5-20.5 parts of modified microcapsules, 0.5-1.5 parts of trimesoyl chloride and 150-180 parts of isoparaffin solvent.

[0011] By adopting the above technical solution, the raw materials in this ratio can maximize the overall chemical stability of the polyamide membrane and extend the service life of the reverse osmosis membrane.

[0012] Optionally, the raw materials of the modified microcapsules include 3-9 parts of carbon quantum dots, 30-40 parts of glyceryl monostearate, 5-10 parts of soybean lecithin, 30-50 parts of polystyrene, 2.5-7.5 parts of graphene oxide and 5-10 parts of Cross-linking agent.

[0013] By adopting the above technical scheme, the modified microcapsules can be used as fillers in the separation layer, changing the stress distribution inside the membrane, reducing local stress concentration, and helping to improve the pore structure of the membrane. On the one hand, it can improve the filtration efficiency and selectivity of the membrane, and on the other hand, it can prevent the pores from deforming or collapsing under pressure, thereby improving the mechanical strength of the membrane and making it more durable in the high-pressure seawater desalination process; it can also serve as an obstacle in the crack expansion process, preventing or slowing down the propagation of cracks in the membrane and improving the crack resistance of the membrane.

[0014] In addition, the addition of modified microcapsules can increase the porosity of the membrane, change the dynamics of water flow through the membrane, reduce the resistance to water flow, and increase the water flux during reverse osmosis membrane desalination.

[0015] Optionally, the cross-linking agent is selected from any one or more of diethylenetriamine, triethylenetetramine, m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, melamine, thiourea, and polyethyleneimine.

[0016] Optionally, the base layer is polyester non-woven fabric.

[0017] By adopting the above technical solution, the polyester non-woven fabric has good mechanical strength and can be used as a base layer to provide additional support.

[0018] Optionally, the porous supporting layer is any one of a polysulfone porous supporting layer and a polyethersulfone porous supporting layer.

[0019] By adopting the above technical solution, the porous structure of polysulfone and polyethersulfone helps to improve the filtration efficiency of the membrane and increase the water flux of the reverse osmosis membrane during seawater desalination.

[0020] In a second aspect, the present application provides a method for preparing a seawater desalination reverse osmosis membrane, using the following technical solution: A method for preparing a seawater desalination reverse osmosis membrane, comprising the following steps: S1: forming a base film by hot pressing the base layer and the porous support layer, and washing the base film to obtain a pretreated base film; S2: Dissolve bis-2-6-N,N-(2-hydroxyethyl)diaminotoluene, triethylamine, camphorsulfonic acid and sodium dodecylsulfonate in water at a solid-liquid ratio of 1:(2.5-3.5), and ultrasonically disperse for 30-40 minutes to obtain an aqueous solution; S3: dissolving trifluoroacetic anhydride, modified microcapsules and trimesoyl chloride in an isoparaffin solvent, and ultrasonically dispersing for 30-40 minutes to obtain an oil phase solution; S4: immersing the upper surface of the pretreated basement membrane in an aqueous solution for 60-90 seconds, removing the residual aqueous solution on the surface of the pretreated basement membrane with a rubber roller, and then immersing the upper surface of the pretreated basement membrane in an oil solution for 40-70 seconds, and taking it out to obtain a reverse osmosis membrane A; S5: The reverse osmosis membrane A is subjected to vacuum heat treatment at 80-85° C. for 15-20 min to obtain the membrane.

[0021] By adopting the above technical scheme, the water phase and oil phase solutions form a uniform and dense separation membrane on the surface of the base membrane through interfacial polymerization reaction, which effectively improves the chemical stability and filtration performance of the reverse osmosis membrane, can effectively prevent the passage of salt and other impurities in seawater, and improve the penetration efficiency and water flux of the reverse osmosis membrane.

[0022] The addition of modified microcapsules effectively enhances the mechanical strength and anti-fouling properties of the membrane and reduces the cleaning frequency of the reverse osmosis membrane. In addition, it can also improve the mechanical properties of the reverse osmosis membrane, enhance its durability in the high-pressure seawater desalination process, and extend its service life.

[0023] The use of environmentally friendly solvents such as isopropyl alcohol and isoparaffin reduces the emission of harmful substances and pollution to the environment. At the same time, these solvents are also easy to volatilize and remove during the subsequent heat treatment process, further reducing environmental risks and meeting the requirements of sustainable development.

[0024] Optionally, the method for preparing the modified microcapsules comprises the following steps: S1: adding glyceryl monostearate to a solvent to dissolve, then adding soybean lecithin and carbon quantum dots, stirring evenly to obtain a core material solution; S2: adding polystyrene to a solvent to dissolve it, then adding graphene oxide, stirring evenly, to obtain a wall material solution; S3: adding the core material solution to the wall material solution, stirring ultrasonically for 30-60 min, then adding a crosslinking agent, and continuing ultrasonic treatment for 30-60 min to obtain a homogeneous emulsion; S4: spray-drying and agglomerating the homogeneous emulsion to form microcapsule structure particles, and then heating the particles to solidify the microcapsule structure particles to obtain modified microcapsules.

[0025] By adopting the above technical scheme, carbon quantum dots are used as one of the core material raw materials in the modified microcapsules. On the one hand, the mechanical strength of the modified microcapsules can be improved to prevent damage during the cleaning process. On the other hand, carbon quantum dots have high chemical inertness, which helps to improve the chemical stability of the membrane, improve chlorine resistance, and can remain stable during the chemical cleaning process to prevent chemical degradation of the membrane.

[0026] Adding graphene oxide to the wall material can not only provide additional mechanical support, enhance the overall rigidity and toughness of the membrane, and prevent damage during high-pressure seawater desalination, but also enhance the hydrophilicity of the membrane, reduce the adsorption of hydrophobic pollutants, and improve the anti-pollution performance of the reverse osmosis membrane, thereby reducing the frequency of chemical or physical cleaning, extending the membrane cleaning cycle, and thus extending the service life of the membrane.

[0027] The synergistic preparation of modified microcapsules using carbon quantum dots and graphene oxide to fill the reverse osmosis membrane can effectively improve the mechanical properties of the reverse osmosis membrane and improve the durability of the reverse osmosis membrane; it can also enhance the anti-pollution ability of the reverse osmosis membrane, reduce the frequency of membrane cleaning, and extend the service life of the membrane; microcapsules can form additional water transmission channels in the separation layer, providing a shorter transmission path for water filtration, which helps to increase water flux.

[0028] Optionally, the reverse osmosis membrane A is pretreated as follows before performing step S5: The pretreatment liquid is evenly applied to the upper surface of the reverse osmosis membrane A and irradiated with ultraviolet light for 30-60 minutes; the pretreatment liquid includes 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl) ammonium hydroxide and water in a mass ratio of 1:(20-50):(500-700).

[0029] By adopting the above technical scheme, 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone is used as a photoinitiator, and under the action of ultraviolet light, a zwitterionic compound [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl) ammonium hydroxide is grafted on the surface of a polyamide membrane for modification to form a protective layer, thereby preparing a polyamide reverse osmosis membrane with zwitterionic groups on the surface. The molecular structure of the zwitterionic polymer contains both anions and cations, and can bind water molecules through hydrogen bonding and solvation of terminal groups, thereby forming a bound hydration layer, which can effectively resist the adsorption of organic pollutants, reduce the cleaning frequency of the reverse osmosis membrane, and extend the service life of the reverse osmosis membrane.

[0030] Optionally, the wavelength of the ultraviolet lamp is 300-400 nm, and the distance between the ultraviolet lamp light source and the upper surface of the reverse osmosis membrane A is 10-20 cm.

[0031] By adopting the above technical solution, the chemical reaction caused by ultraviolet irradiation can be accurately controlled through specific wavelengths and light source distances, so that the efficiency of the cross-linking reaction on the membrane surface is maximized, thereby enhancing the durability and anti-pollution ability of the membrane.

[0032] In summary, this application has the following beneficial effects: 1. Since the present application adopts bis-2-6-N, N-(2-hydroxyethyl)diaminotoluene to replace m-phenylenediamine in combination with triethylamine and trifluoroacetic anhydride to prepare the separation layer of the polyamide composite membrane, the reaction activity of the amide bond can be effectively reduced, the amide bond can be protected, the antioxidant performance and chlorine resistance of the reverse osmosis membrane can be effectively improved, and the service life of the reverse osmosis membrane can be extended.

[0033] 2. In the present application, modified microcapsules are prepared using carbon quantum dots as core material and graphene oxide as wall material and filled in the separation layer of the reverse osmosis membrane, which can effectively improve the mechanical properties of the reverse osmosis membrane and make it more durable in the high-pressure seawater desalination process; at the same time, it can improve the hydrophilicity of the reverse osmosis membrane, thereby improving the anti-pollution ability of the membrane, helping to reduce the cleaning frequency of the reverse osmosis membrane and thus extending the service life of the membrane.

[0034] 3. In the preparation method of the present application, the separation layer is modified by ultraviolet light irradiation, and the zwitterionic compound is grafted onto the surface of the separation layer to form a protective layer, thereby improving the oxidation resistance of the reverse osmosis membrane and extending the service life of the reverse osmosis membrane. DETAILED DESCRIPTION

[0035] The following examples further illustrate the present application in detail.

[0036] raw material Unless otherwise specified, the raw materials used in the preparation examples, embodiments and comparative examples in this application are all commercially available products, specifically: Bis-2-6-N,N-(2-hydroxyethyl)diaminotoluene, selected from Hubei Fangde New Materials Co., Ltd., CAS number is 149330-25-6; Triethylamine, selected from Beijing Inokai Technology Co., Ltd., G00019; Camphorsulfonic acid, selected from Beijing Inokai Technology Co., Ltd., A71674; Trifluoroacetic anhydride, selected from Shanghai Myrel Biochemical Technology Co., Ltd., N07715; Sodium dodecyl sulfate, selected from Beijing Inokai Technology Co., Ltd., A20415; Trimesoyl chloride, selected from Kandis Chemical, 1,3,5-trimesoyl chloride; The isoparaffin solvent is isododecane, selected from Zhengzhou Petrochemical, IPC12; Carbon quantum dots, selected from Xianfeng Nano, XF253; Glyceryl monostearate, selected from Beijing Inokai Technology Co., Ltd., T36454; Soy lecithin, selected from Beijing Inokai Technology Co., Ltd., 69014981; Polystyrene, A41119A84978; Graphene oxide, selected from Xianfeng Nano, XF002-2; Diethylenetriamine, selected from Beijing Inokai Technology Co., Ltd., A41119; Triethylenetetramine, selected from Beijing Inokai Technology Co., Ltd., A56756; p-phenylenediamine, selected from Beijing Inokai Technology Co., Ltd., A66404; m-phenylenediamine, selected from Beijing Inokai Technology Co., Ltd., A61672; 2-Hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone, selected from Beijing Inokai Technology Co., Ltd., A89077; [2-(Methacryloyloxy)ethyl]dimethyl-(3-sulfonatepropyl)ammonium hydroxide, selected from Beijing Inokai Technology Co., Ltd., A03802.

[0037] Preparation example of modified microcapsules Preparation Example 1 The modified microcapsules, the raw materials and the amounts of the raw materials are shown in Table 1, wherein the crosslinking agent is diethylenetriamine.

[0038] Table 1 Components Preparation Example 1 Preparation Example 2 Preparation Example 3 Preparation Example 4 Carbon quantum dots / g 5 3 6 9 Glyceryl monostearate / g 36 30 40 34 Soy lecithin / g 6 5 8 10 Polystyrene / g 38 30 50 43 Graphene oxide / g 5 7.5 2.5 4.5 Crosslinking agent / g 7 5 10 8 The preparation method of the modified microcapsules comprises the following steps: S1: Dissolve glyceryl monostearate in 60% ethanol solution at a solid-liquid ratio of 1:5, then add soybean lecithin and carbon quantum dots, stir evenly, and obtain a core material solution; S2: adding polystyrene to a 60% ethanol solution at a solid-liquid ratio of 1:5 to dissolve the polystyrene, then adding graphene oxide and stirring evenly to obtain a wall material solution; S3: adding the core material solution to the wall material solution, adding a crosslinking agent after ultrasonic stirring for 40 min, and continuing ultrasonic treatment for 40 min to obtain a homogeneous emulsion; S4: spray-drying and agglomerating the homogeneous emulsion to form microcapsule structure particles, and then heating the particles to solidify the microcapsule structure particles to obtain modified microcapsules.

[0039] Preparation Example 2 The modified microcapsules, the raw materials and materials are shown in Table 1, wherein the crosslinking agent is triethylenetetramine, and the preparation method thereof comprises the following steps: S1: Dissolve glyceryl monostearate in 60% ethanol solution at a solid-liquid ratio of 1:5, then add soybean lecithin and carbon quantum dots, stir evenly, and obtain a core material solution; S2: adding polystyrene to a 60% ethanol solution at a solid-liquid ratio of 1:5 to dissolve the polystyrene, then adding graphene oxide and stirring evenly to obtain a wall material solution; S3: adding the core material solution to the wall material solution, adding a crosslinking agent after ultrasonic stirring for 30 min, and continuing ultrasonic treatment for 60 min to obtain a homogeneous emulsion; S4: spray-drying and agglomerating the homogeneous emulsion to form microcapsule structure particles, and then heating the particles to solidify the microcapsule structure particles to obtain modified microcapsules.

[0040] Preparation Example 3 The modified microcapsules, the raw materials and materials are shown in Table 1, wherein the crosslinking agent is p-phenylenediamine, and the preparation method thereof comprises the following steps: S1: Dissolve glyceryl monostearate in 60% ethanol solution at a solid-liquid ratio of 1:5, then add soybean lecithin and carbon quantum dots, stir evenly, and obtain a core material solution; S2: adding polystyrene to a 60% ethanol solution at a solid-liquid ratio of 1:5 to dissolve the polystyrene, then adding graphene oxide and stirring evenly to obtain a wall material solution; S3: adding the core material solution to the wall material solution, adding the crosslinking agent after ultrasonic stirring for 60 minutes, and continuing the ultrasonic treatment for 30 minutes to obtain a homogeneous emulsion; S4: spray-drying and agglomerating the homogeneous emulsion to form microcapsule structure particles, and then heating the particles to solidify the microcapsule structure particles to obtain modified microcapsules.

[0041] Preparation Example 4 The difference between the modified microcapsules and Preparation Example 1 is that the raw materials and materials used are as shown in Table 1, and the other steps are the same as Preparation Example 1.

[0042] Preparation Example 5 The modified microcapsules are different from those in Preparation Example 1 in that no carbon quantum dots are added, the carbon quantum dots in the raw materials are replaced with an equal mass of graphene oxide, and the other steps are the same as those in Preparation Example 1.

[0043] Preparation Example 6 The modified microcapsules are different from those in Preparation Example 1 in that graphene oxide is not added, the graphene oxide in the raw material is replaced by carbon quantum dots of equal mass, and the other steps are the same as those in Preparation Example 1. Example

[0044] Example 1 A seawater desalination reverse osmosis membrane comprises a base membrane layer and a separation layer, wherein the base membrane layer comprises a substrate layer and a porous support layer, and the raw materials and the materials used for the raw materials are shown in Table 2, wherein the substrate layer is a polyester non-woven fabric, the porous support layer is a polysulfone porous support layer, and the modified microcapsules are obtained by Preparation Example 1.

[0045] Table 2 The method for preparing the above-mentioned seawater desalination reverse osmosis membrane comprises the following steps: S1: forming a base membrane by hot pressing a polyester non-woven fabric and a polysulfone porous support layer, soaking the base membrane in a 25% isopropanol solution for 10 minutes, taking it out, washing the isopropanol solution on the surface with water and setting it aside to obtain a pretreated base membrane; S2: Dissolve bis-2-6-N,N-(2-hydroxyethyl)diaminotoluene, triethylamine, camphorsulfonic acid and sodium dodecylsulfonate in water at a solid-liquid ratio of 1:3, and ultrasonically disperse for 30 minutes to obtain an aqueous solution; S3: dissolving trifluoroacetic anhydride, modified microcapsules and trimesoyl chloride in an isoparaffin solvent, and ultrasonically dispersing for 40 min to obtain an oil phase solution; S4: immersing the upper surface of the pretreated basement membrane in an aqueous solution for 60 seconds, removing the residual aqueous solution on the surface of the pretreated basement membrane with a rubber roller, and then immersing the upper surface of the pretreated basement membrane in an oil solution for 40 seconds, and taking it out to obtain a reverse osmosis membrane A; S5: evenly apply the pretreatment liquid to the upper surface of the reverse osmosis membrane A, and irradiate with ultraviolet light for 30 minutes to obtain the reverse osmosis membrane B; the pretreatment liquid is prepared by mixing 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl) ammonium hydroxide and water in a mass ratio of 1:50:700; the wavelength of the ultraviolet lamp is 300-400nm, and the distance between the ultraviolet light source and the upper surface of the reverse osmosis membrane A is 10-20cm; S6: The reverse osmosis membrane B is subjected to vacuum heat treatment at 85° C. for 15 min to obtain.

[0046] Example 2 A seawater desalination reverse osmosis membrane comprises a base membrane layer and a separation layer, wherein the base membrane layer comprises a substrate layer and a porous support layer, and the raw materials and the materials used for the raw materials are shown in Table 2, wherein the substrate layer is a polyester non-woven fabric, the porous support layer is a polyethersulfone porous support layer, and the modified microcapsules are obtained by Preparation Example 2.

[0047] The method for preparing the above-mentioned seawater desalination reverse osmosis membrane comprises the following steps: S1: forming a base membrane by hot pressing a polyester non-woven fabric and a polyethersulfone porous support layer, soaking the base membrane in a 25% isopropanol solution for 10 minutes, taking it out, washing the isopropanol solution on the surface with water and setting it aside to obtain a pretreated base membrane; S2: Dissolve bis-2-6-N,N-(2-hydroxyethyl)diaminotoluene, triethylamine, camphorsulfonic acid and sodium dodecylsulfonate in water at a solid-liquid ratio of 1:2.5, and ultrasonically disperse for 40 minutes to obtain an aqueous solution; S3: dissolving trifluoroacetic anhydride, modified microcapsules and trimesoyl chloride in an isoparaffin solvent, and ultrasonically dispersing for 30 minutes to obtain an oil phase solution; S4: immerse the upper surface of the pretreated base membrane in an aqueous solution for 90 seconds, remove the residual aqueous solution on the surface of the pretreated base membrane with a rubber roller, and then immerse the upper surface of the pretreated base membrane in an oil solution for 70 seconds, and obtain reverse osmosis membrane A after taking it out; S5: evenly apply the pretreatment liquid to the upper surface of reverse osmosis membrane A, and irradiate with ultraviolet light for 60 minutes to obtain reverse osmosis membrane B; the pretreatment liquid is a mixture of 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl) ammonium hydroxide and water in a mass ratio of 1:20:500; the wavelength of the ultraviolet lamp is 300-400nm, and the distance between the ultraviolet light source and the upper surface of the reverse osmosis membrane A is 10-20cm; S6: The reverse osmosis membrane B is subjected to vacuum heat treatment at 80° C. for 20 min to obtain.

[0048] Example 3 A seawater desalination reverse osmosis membrane, which is different from Example 1 in that the raw materials and the materials used are shown in Table 2, wherein the modified microcapsules are obtained from Preparation Example 3.

[0049] The method for preparing the above-mentioned seawater desalination reverse osmosis membrane comprises the following steps: S1: forming a base membrane by hot pressing a polyester non-woven fabric and a polyethersulfone porous support layer, soaking the base membrane in a 25% isopropanol solution for 10 minutes, taking it out, washing the isopropanol solution on the surface with water and setting it aside to obtain a pretreated base membrane; S2: Dissolve bis-2-6-N,N-(2-hydroxyethyl)diaminotoluene, triethylamine, camphorsulfonic acid and sodium dodecylsulfonate in water at a solid-liquid ratio of 1:3.5, and ultrasonically disperse for 35 minutes to obtain an aqueous solution; S3: dissolving trifluoroacetic anhydride, modified microcapsules and trimesoyl chloride in an isoparaffin solvent, and ultrasonically dispersing for 30 minutes to obtain an oil phase solution; S4: immerse the upper surface of the pretreated base membrane in an aqueous solution for 70 seconds, remove the residual aqueous solution on the surface of the pretreated base membrane with a rubber roller, and then immerse the upper surface of the pretreated base membrane in an oil solution for 50 seconds, and obtain reverse osmosis membrane A after taking it out; S5: evenly apply the pretreatment liquid to the upper surface of reverse osmosis membrane A, and irradiate with ultraviolet light for 60 minutes to obtain reverse osmosis membrane B; the pretreatment liquid is prepared by mixing 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl) ammonium hydroxide and water in a mass ratio of 1:40:600; the wavelength of the ultraviolet lamp is 300-400nm, and the distance between the ultraviolet light source and the upper surface of reverse osmosis membrane A is 10-20cm; S6: The reverse osmosis membrane B is subjected to vacuum heat treatment at 85° C. for 15 min to obtain.

[0050] Example 4 A seawater desalination reverse osmosis membrane, which is different from Example 1 in that the raw materials and the materials used are shown in Table 2, wherein the modified microcapsules are obtained by Preparation Example 4, and the other steps are the same as Example 1.

[0051] Example 5 A seawater desalination reverse osmosis membrane is different from Example 1 in that the modified microcapsules are obtained from Preparation Example 5, and the other steps are the same as those of Example 1.

[0052] Example 6 A seawater desalination reverse osmosis membrane is different from Example 1 in that the modified microcapsules are obtained from Preparation Example 6, and the other steps are the same as those of Example 1.

[0053] Example 7 A seawater desalination reverse osmosis membrane is different from Example 1 in that the ultraviolet light irradiation modification treatment of step S5 is not performed. Step S5 specifically comprises: performing vacuum heat treatment on the reverse osmosis membrane A at 100° C. for 15 minutes. The other steps are the same as those of Example 1.

[0054] Comparative Example Comparative Example 1 A seawater desalination reverse osmosis membrane, which differs from Example 1 in that bis-2-6-N,N-(2-hydroxyethyl)diaminotoluene in the raw material is replaced by an equal mass of m-phenylenediamine, and the other steps are the same as those in Example 1.

[0055] Comparative Example 2 A seawater desalination reverse osmosis membrane, which differs from Example 1 in that trifluoroacetic anhydride is not used, the trifluoroacetic anhydride in the raw material is replaced by an isomeric alkane solvent of equal mass, and the other steps are the same as those in Example 1.

[0056] Comparative Example 3 A seawater desalination reverse osmosis membrane is different from Example 1 in that modified microcapsules are not used, the modified microcapsules in the raw materials are replaced by an isoparaffin solvent of equal mass, and the other steps are the same as those in Example 1.

[0057] Performance testing The seawater desalination reverse osmosis membranes prepared in Examples 1-7 and Comparative Examples 1-3 were subjected to initial performance tests, and separation performance tests were performed on the water flux, salt rejection rate and tensile strength of the reverse osmosis membranes according to GB / T32373-2015 "Test Method for Reverse Osmosis Membrane".

[0058] Antioxidant test: The tested membrane was immersed in a NaClO solution with an effective chlorine content of 1000 ppm at 5°C for 24 hours, and the pH was adjusted to 7.0. The membrane was then taken out and washed with deionized water, and then immersed in a 1% sodium sulfite solution for reduction for 10 minutes. After washing again with deionized water, the membrane performance was retested.

[0059] Each group of performance test experiments before and after antioxidant were conducted three times, and the average values ​​of the three groups of tests were recorded in Table 3.

[0060] Table 3 According to the performance test data in Table 3, it can be seen that the seawater desalination reverse osmosis membrane of the present application has high water flux, good osmotic separation effect and durability, less desalination rate loss after oxidation treatment, shows excellent antioxidant performance, and has good application prospects.

[0061] According to the performance test results of Examples 1-4, Examples 5-6 and Comparative Example 3, it can be seen that the use of modified microcapsules can significantly improve the oxidation resistance of seawater desalination reverse osmosis membranes, improve the mechanical properties of reverse osmosis membranes, prevent damage during use, enhance durability during high-pressure seawater desalination, and form additional water transmission channels in the separation layer to provide a shorter transmission path for water filtration, thereby increasing water flux. Carbon quantum dots as core materials and graphene oxide as wall materials are used to prepare modified microcapsules to fill reverse osmosis membranes. Compared with using only carbon quantum dots or graphene oxide as functional raw materials to prepare modified microcapsules to fill reverse osmosis membranes, it can more significantly and effectively improve the oxidation resistance and mechanical properties of reverse osmosis membranes, which helps to improve the durability of reverse osmosis membranes.

[0062] According to the performance test results of Examples 1-4 and Comparative Examples 1-2, it can be seen that the use of bis-2-6-N,N-(2-hydroxyethyl)diaminotoluene instead of m-phenylenediamine as a raw material to prepare a reverse osmosis membrane can significantly improve the oxidation resistance of the reverse osmosis membrane. Trifluoroacetic anhydride introduces a -CF3 strong electron-withdrawing group as a protecting group, which can effectively protect the amide bond from oxidative degradation, thereby improving the oxidation resistance of the reverse osmosis membrane and maintaining the excellent application performance of the reverse osmosis membrane.

[0063] According to the performance test results of Examples 1-4 and Example 7, it can be seen that under the action of ultraviolet light, the zwitterionic compound [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl)ammonium hydroxide is grafted onto the surface of the polyamide membrane for modification to form a protective layer, which can further enhance the oxidation resistance of the reverse osmosis membrane, prevent the reverse osmosis membrane from being oxidized and degraded during long-term use, and help maintain the excellent performance of the reverse osmosis membrane.

[0064] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed. However, as long as it is within the scope of the claims of the present application, it shall be protected by the patent law.

Claims

1. A seawater desalination reverse osmosis membrane, comprising a base membrane layer and a separation layer, wherein the base membrane layer comprises a substrate layer and a porous support layer, characterized in that: The raw materials of the separation layer include bis-2-6-N, N-(2-hydroxyethyl) diaminotoluene, triethylamine, camphorsulfonic acid, trifluoroacetic anhydride, sodium dodecylsulfonate, modified microcapsules, trimesoyl chloride and isoparaffin solvent.

2. The seawater desalination reverse osmosis membrane according to claim 1, characterized in that: In parts by weight, the raw materials of the separation layer include 15-20 parts of bis-2-6-N,N-(2-hydroxyethyl)diaminotoluene, 10-15 parts of triethylamine, 20-30 parts of camphorsulfonic acid, 10-15 parts of trifluoroacetic anhydride, 0.5-1.5 parts of sodium dodecyl sulfate, 10.5-20.5 parts of modified microcapsules, 0.5-1.5 parts of trimesoyl chloride and 150-180 parts of isoparaffin solvent.

3. The seawater desalination reverse osmosis membrane according to claim 2, characterized in that: In parts by weight, the raw materials of the modified microcapsules include 3-9 parts of carbon quantum dots, 30-40 parts of glyceryl monostearate, 5-10 parts of soybean lecithin, 30-50 parts of polystyrene, 2.5-7.5 parts of graphene oxide and 5-10 parts of a cross-linking agent.

4. The seawater desalination reverse osmosis membrane according to claim 3, characterized in that: The crosslinking agent is selected from any one or more of diethylenetriamine, triethylenetetramine, m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, melamine, thiourea and polyethyleneimine.

5. The seawater desalination reverse osmosis membrane according to claim 1, characterized in that: The base layer is polyester non-woven fabric.

6. The seawater desalination reverse osmosis membrane according to claim 1, characterized in that: The porous support layer is any one of a polysulfone porous support layer and a polyethersulfone porous support layer.

7. The method for preparing a seawater desalination reverse osmosis membrane according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1: forming a base film by hot pressing the base layer and the porous support layer, and washing the base film to obtain a pretreated base film; S2: Dissolve bis-2-6-N,N-(2-hydroxyethyl)diaminotoluene, triethylamine, camphorsulfonic acid and sodium dodecylsulfonate in water at a solid-liquid ratio of 1:(2.5-3.5), and ultrasonically disperse for 30-40 minutes to obtain an aqueous solution; S3: dissolving trifluoroacetic anhydride, modified microcapsules and trimesoyl chloride in an isoparaffin solvent, and ultrasonically dispersing for 30-40 minutes to obtain an oil phase solution; S4: immersing the upper surface of the pretreated basement membrane in an aqueous solution for 60-90 seconds, removing the residual aqueous solution on the surface of the pretreated basement membrane with a rubber roller, and then immersing the upper surface of the pretreated basement membrane in an oil solution for 40-70 seconds, and taking it out to obtain a reverse osmosis membrane A; S5: The reverse osmosis membrane A is subjected to vacuum heat treatment at 80-85° C. for 15-20 min to obtain the membrane.

8. The method for preparing a seawater desalination reverse osmosis membrane according to claim 7, characterized in that: The preparation method of the modified microcapsule comprises the following steps: S1: adding glyceryl monostearate to a solvent to dissolve, then adding soybean lecithin and carbon quantum dots, stirring evenly to obtain a core material solution; S2: adding polystyrene to a solvent to dissolve it, then adding graphene oxide, stirring evenly, to obtain a wall material solution; S3: adding the core material solution to the wall material solution, stirring ultrasonically for 30-60 min, then adding the crosslinking agent, and continuing ultrasonic treatment for 30-60 min to obtain a homogeneous emulsion; S4: spray-drying and agglomerating the homogeneous emulsion to form microcapsule structure particles, and then heating the particles to solidify the microcapsule structure particles to obtain modified microcapsules.

9. The method for preparing a seawater desalination reverse osmosis membrane according to claim 7, characterized in that: The reverse osmosis membrane A is pretreated as follows before performing step S5: The pretreatment liquid is evenly applied to the upper surface of the reverse osmosis membrane A and irradiated with ultraviolet light for 30-60 minutes; the pretreatment liquid comprises 2-hydroxy-4′-(2-hydroxyethoxy)-2-methylpropiophenone, [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfonic acid propyl) ammonium hydroxide and water in a mass ratio of 1:(20-50):(500-700).

10. The method for preparing a seawater desalination reverse osmosis membrane according to claim 9, characterized in that: The wavelength of the ultraviolet lamp is 300-400nm, and the distance between the ultraviolet lamp source and the upper surface of the reverse osmosis membrane A is 10-20cm.

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