High-performance reverse osmosis membrane and preparation method thereof

Abstract

The invention relates to the technical field of water treatment, in particular to a high-performance reverse osmosis membrane and a preparation method thereof. The high-performance reverse osmosis membrane comprises a polysulfone support layer and a polyamide separation layer, the polyamide separation layer is prepared from the following raw materials in parts by weight: 1.5 to 3 parts of m-phenylenediamine, 0.5 to 1.5 parts of boric acid modified diethylenetriamine, 1.5 to 3 parts of hyperbranched modified titanium dioxide nanotubes, 2.5 to 3 parts of a pH regulator, 0.18 to 0.5 part of a surfactant, 0.5 to 1.5 parts of an acid acceptor, 0.5 to 1.5 parts of acyl chloride monomers and 99 to 108 parts of an alkane solvent. The technical problems of insufficient TOC interception, poor pollution resistance and the like are solved; the reverse osmosis membrane has better retention rate and water flux, the removal rate of carbon-containing organic matters is improved, and membrane pollution is effectively prevented.

Description

Technical Field

[0001] This application relates to the field of water treatment technology, and in particular to a high-performance reverse osmosis membrane and its preparation method. Background Technology

[0002] Organic matter in water is a general term for all kinds of compounds with carbon as their core. Total organic carbon (TOC) is a key indicator for quantifying its total amount and directly reflects the degree of water pollution. These substances come from natural organic matter from the decomposition of animal and plant residues, as well as anthropogenic pollutants such as industrial wastewater, pesticides, and emerging pollutants. They not only react with disinfectants to produce carcinogenic byproducts but also affect the quality of products in industries such as electronics and pharmaceuticals, and contaminate water treatment equipment. Traditional processes such as coagulation and adsorption have limited effectiveness in removing small-molecule organic matter. Reverse osmosis technology, due to its ability to effectively retain organic matter for TOC removal, has broad application prospects. Mainstream products consist of a polysulfone support layer and a polyamide functional layer; the formation of the polyamide layer through interfacial polymerization is key to retaining organic matter.

[0003] Existing reverse osmosis membranes suffer from two main problems. First, the active layer has a wide pore size distribution, resulting in poor retention of small-molecule organic pollutants. In practical applications, the TOC rejection rate is generally low, making it difficult to meet the requirements of high-purity water treatment. Second, traditional polyamide membranes have a highly hydrophobic surface, making them prone to adsorbing hydrophobic organic pollutants and causing membrane fouling. Although existing technologies have improved their antifouling properties and removal rates through the doping of hydrophilic substances and optimization of polymerization conditions, they still face challenges such as limited removal of small-molecule organic matter, uneven dispersion and poor stability of nanomaterials, and complex processes that hinder mass production. Summary of the Invention

[0004] To effectively construct a reverse osmosis membrane with high organic matter retention and long-term stability, this application provides a high-performance reverse osmosis membrane and its preparation method.

[0005] This application provides a high-performance reverse osmosis membrane and its preparation method, which adopts the following technical solution: A high-performance reverse osmosis membrane includes a polysulfone support layer and a polyamide separation layer; by weight, the raw materials of the polyamide separation layer include: 1.5-3 parts m-phenylenediamine, 0.5-1.5 parts borate-modified diethylenetriamine, 1.5-3 parts hyperbranched modified titanium dioxide nanotubes, 2.5-3 parts pH adjuster, 0.18-0.5 parts surfactant, 0.5-1.5 parts acid acceptor, 0.5-1.5 parts acyl chloride monomer, and 99-108 parts alkane solvent.

[0006] This application uses a polysulfone support layer as a substrate and introduces hyperbranched modified titanium dioxide nanotubes, m-phenylenediamine, and borate-modified diethylenetriamine as raw materials in the preparation of the polyamide separation layer. Through the hollow tubular structure and hyperbranched dense structure of the hyperbranched modified titanium dioxide nanotubes, it can efficiently conduct current and reduce the TOC removal rate decay caused by adsorbed organic matter on the membrane surface. Through the cross-linking reaction between m-phenylenediamine and borate-modified diethylenetriamine and acyl chloride monomer, the weak coordination adsorption of borate groups is introduced to enhance TOC retention and improve the small molecule TOC retention efficiency.

[0007] Specifically, titanium dioxide nanotubes are first selected. Their hollow tubular structure can construct a continuous water molecule transport pathway, while the excellent antibacterial properties of titanium dioxide, combined with the steric hindrance effect of the tubular structure, effectively reduce the aggregation and adhesion of organic matter on the surface layer, minimizing the TOC removal rate decline caused by membrane fouling. Hyperbranching modification of the titanium dioxide nanotubes further prevents nanotube aggregation, ensuring sufficient exposure of adsorption sites and further improving the TOC removal rate. The introduction of a hyperbranched structure with a three-dimensional spatial configuration and abundant terminal sites allows its active groups to bind small-molecule hydrophilic TOCs such as methanol and acetic acid in water through hydrogen bonding, preventing the polyamide backbone from being oxidized and destroyed. Simultaneously, the borate groups in borate-based diethylenetriamine can act as Lewis acid sites, forming stable and reversible coordination bonds with the hydroxyl, carboxyl, and amide groups of small-molecule TOCs, enhancing the capture capacity of organic matter in water and further improving the overall TOC retention rate. This, in turn, achieves the removal of a large amount of low-molecular-weight, highly hydrophilic substances from water. The combined effect of these two methods effectively improves the TOC removal rate. Furthermore, the bonding between borate-modified diethylenetriamine and hyperbranched nanotubes, and the polymerization of borate-modified diethylenetriamine and acyl chloride monomers, facilitate the anchoring of borate groups and nanotubes within the polyamide framework, preventing filler loss due to water erosion and fully leveraging their synergistic effect in capturing organic matter and improving TOC removal. Building upon this, this application, through the selection of aromatic ring structure diamines, endows the polyamide framework with good rigidity and stability. The amino groups in the molecule undergo amidation reactions with acyl chloride monomers, constructing a dense cross-linked structure that achieves secondary retention of unadsorbed small-molecule TOCs and effectively improves the desalination rate of the reverse osmosis membrane. The flexible alkyl chain of borate-modified diethylenetriamine, combined with the rigid aromatic ring of m-phenylenediamine, ensures both the density and improved toughness of the separation layer, reduces the adsorption and deposition of large-molecule organic matter such as humic acid, retains sufficient amino groups to participate in the amidation reaction, increases the cross-linking density, and optimizes the sieve pore size. Therefore, the components of this application work together to form a highly efficient TOC retention system, ensuring that water flux is not affected. Their interaction ensures long-term stability of the membrane structure, extends membrane lifespan, and systematically improves technical problems such as insufficient small molecule TOC retention and poor antifouling.

[0008] Preferably, the preparation method of hyperbranched modified titanium dioxide nanotubes includes: (1) taking trimethylolpropane, mercaptopropionic acid and stannous octoate, heating to 80-90℃ under nitrogen protection, and reacting for 3-5h; then adding adipic dihydrazide and p-toluenesulfonic acid, and reacting at 100-110℃ for 3-5h to obtain hyperbranched polymer; (2) taking hydroxylated titanium dioxide nanotubes and dispersing them in N,N-dimethylformamide for 10-15min, then adding the hyperbranched polymer, reacting at 100-115℃ for 4-5h, cooling to room temperature, centrifuging, washing and drying to obtain hyperbranched modified titanium dioxide nanotubes.

[0009] More preferably, the mass ratio of hydroxylated titanium dioxide nanotubes to hyperbranched polymers is 1:(0.5-0.7).

[0010] Preferably, the preparation method of borate-modified diethylenetriamine includes: adding diethylenetriamine to ethanol and heating to 40-50°C; adding to an ethanol solution containing 3-carboxyphenylboronic acid and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide and stirring for 5-6 hours to obtain borate-modified diethylenetriamine.

[0011] Hyperbranched titanium dioxide nanotubes introduce a large number of hydrazide and mercapto groups onto their surface. The hyperbranched structure, with its high specific surface area and abundant terminal sites, along with its three-dimensional branched configuration, allows the hydrazide groups to be evenly distributed and fully exposed, significantly increasing the probability of contact with small-molecule TOCs. The hydrazide groups can form targeted adsorption with the hydroxyl and carboxyl groups of small-molecule hydrophilic TOCs in water through hydrogen bonds, improving the TOC removal rate. The mercapto groups, acting as antioxidant sites, preferentially react with oxidizing ions in the water, protecting the polyamide framework from damage. Hyperbranched titanium dioxide nanotubes further improve the density and integrity of the separation layer, further preventing the shedding of inorganic matter and the dissolution of organic matter. Simultaneously, the hollow tubular structure within the nanotubes... The construction of interconnected water molecule channels ensures membrane performance. Boric acid-modified diethylenetriamine introduces boric acid groups as Lewis acid sites, which can coordinate with oxygen-containing carbonaceous organic compounds to form coordination bonds. These coordination bonds mutually promote hydrogen bond adsorption with hydrazide groups, achieving efficient capture of low-polarity TOCs (carbonaceous organic compounds). After capture, TOC desorption can be achieved under relatively mild conditions during membrane cleaning, regenerating the adsorption sites and improving the rapid performance degradation of traditional adsorption-type membranes after adsorption saturation. Furthermore, the thiol groups of the hyperbranched polymer and the hydroxyl groups of the boric acid-modified diethylenetriamine enhance the hydrophilicity of the separation layer surface, reducing the physical adsorption and deposition of large molecular weight organic compounds and lowering the risk of membrane fouling. Therefore, the hydrogen bond adsorption of hydrazide groups and the coordination adsorption of boric acid groups mutually promote each other, significantly improving the removal rate of carbonaceous organic compounds, ultimately achieving the high-performance characteristics of the reverse osmosis membrane described in this application.

[0012] Preferably, the raw materials for the polysulfone support layer include: 20-25 parts of quaternary ammonium salt modified polysulfone, 4-6 parts of polyvinylpyrrolidone, and 60-75 parts of N,N-dimethylformamide.

[0013] More preferably, the preparation method of quaternary ammonium salt modified polysulfone includes: taking polysulfone and adding N,N-dimethylformamide, heating to 50-60℃ and stirring for 18-24h under nitrogen protection, adding anhydrous K2CO3 and stirring for 10-15min, adding glycidyltrimethylammonium chloride dropwise, stirring and reacting for 4-6h, washing and drying to obtain quaternary ammonium salt modified polysulfone.

[0014] Quaternary ammonium salt groups, acting as cationic active sites, can adsorb negatively charged total organic carbon components in water, such as humic acids and sulfonic acids, through electrostatic attraction, thus achieving TOC retention. The electrostatic adsorption of quaternary ammonium salt groups in the support layer can pre-retain some large-molecule TOCs, reducing the retention burden on the polyamide separation layer. This synergistic effect with the separation layer's focus on capturing small-molecule TOCs enhances the overall TOC removal efficiency. The hydrophilicity of the modified quaternary ammonium salt groups improves the water wettability of the support layer, reduces water molecule mass transfer resistance, and, along with the hydrophilic groups such as borate and hydroxyl groups in the polyamide layer, further optimizes the overall water flux. Furthermore, the antibacterial properties of the quaternary ammonium salt groups in the support layer and the antibacterial properties of the titanium dioxide nanotubes in the separation layer work together to decompose microorganisms and improve the operational stability of the membrane. The polarity of the quaternary ammonium salt groups can strengthen the interfacial bonding between the support layer and the separation layer, preventing membrane peeling during operation. The rigid framework of the modified polysulfone provides stable support for the polyamide layer, ensuring that the separation layer maintains a dense structure under high pressure. Through the collaboration of multiple parties, the overall operational stability and TOC removal capacity of the reverse osmosis membrane are improved.

[0015] Preferably, the pH adjuster is one of camphor sulfonic acid and citric acid; the surfactant is one of sodium dodecyl sulfonate, sodium dodecyl sulfate, and sodium dodecylbenzene sulfonate; and the acid acceptor is one of sodium hydroxide, sodium carbonate, and trisodium phosphate.

[0016] Preferably, the acyl chloride monomers include one or more of phthaloyl chloride, benzenesulfonyl chloride, 2,5-dichlorobenzenesulfonyl chloride, 2,5-dibromobenzenesulfonyl chloride, 3,4-dibromobenzenesulfonyl chloride, 1,3-benzenedisulfonyl chloride, and pyromellitic acid chloride.

[0017] Preferably, the alkane solvent is one or more selected from n-hexane, cyclohexane, ethylcyclohexane, and n-heptane.

[0018] Secondly, this application provides a high-performance reverse osmosis membrane and its preparation method, which adopts the following technical solution: A high-performance reverse osmosis membrane and its preparation method include the following steps: S1, taking quaternary ammonium salt modified polysulfone, N,N-dimethylformamide and polyvinylpyrrolidone, mixing and standing, degassing and filtering to obtain casting solution, spraying the casting solution onto non-woven fabric, placing it in water coagulation solution to form a membrane, obtaining a polysulfone support layer; S2, taking m-phenylenediamine, borate-modified diethylenetriamine, hyperbranched modified titanium dioxide nanotubes, pH adjuster, surfactant and acid acceptor added to water to obtain an aqueous phase solution, coating the aqueous phase solution onto the polysulfone support layer, and drying; S3, taking acyl chloride monomer and alkane solvent, mixing to obtain an oil phase solution, coating the oil phase solution onto the membrane in step S2 for reaction, drying, to obtain a high-performance reverse osmosis membrane.

[0019] In summary, this application includes at least one of the following beneficial technical effects: 1. This application uses a polysulfone support layer as a substrate and introduces hyperbranched modified titanium dioxide nanotubes into the polyamide separation layer to interact with m-phenylenediamine and borate-modified diethylenetriamine. Through the hollow tubular structure and hyperbranched dense structure of the hyperbranched modified titanium dioxide nanotubes, it can efficiently conduct water and reduce the TOC removal rate decay caused by organic pollution. Through the cross-linking reaction of m-phenylenediamine and diethylenetriamine with acyl chloride monomers, the weak coordination adsorption of borate groups is introduced to enhance TOC retention, improve the small molecule TOC retention efficiency, and avoid problems such as filler loss and membrane fouling.

[0020] 2. After hyperbranching modification, titanium dioxide nanotubes have a large number of hydrazide groups and mercapto groups introduced on their surface. The hydrazide groups can form targeted adsorption with the hydroxyl and carboxyl groups of hydrophilic TOC in water through hydrogen bonds. The high specific surface area and abundant terminal sites of the hyperbranched structure, along with its three-dimensional branched configuration, enable the hydrazide groups to be evenly distributed and fully exposed, greatly increasing the contact probability with TOC and significantly improving the removal rate of carbon-containing organic matter. Detailed Implementation

[0021] The raw materials used in this application include titanium dioxide nanotubes purchased from Degussa P25; acyl chloride monomers, namely trimesoyl pyromellitic chloride; and alkane solvents, namely n-heptane. The molecular sieve was purchased from Aladdin, catalog number M103739; the others were from conventional commercial brands or obtained through conventional preparation processes.

[0022] Preparation Example 1 Preparation of hyperbranched modified titanium dioxide nanotubes: (1) Take 5g of trimethylolpropane, 12g of mercaptopropionic acid and 0.15g of stannous octoate, and react at 90℃ for 4h under nitrogen protection; then add 8.5g of adipate dihydrazide and 0.1g of p-toluenesulfonic acid, heat to 110℃ and stir at 300rpm / min for 5h, and dry at 90℃ under vacuum of -0.095MPa for 2h to obtain hyperbranched polymer; (2) Take 10g of titanium dioxide nanotubes and add 150mL of water, sonicate for 20min and add 1.5g of hydroxide. Sodium hydroxide was stirred and placed in a constant temperature water bath at 60℃. It was magnetically stirred for 1 hour, washed with water until neutral, and vacuum dried at 80℃ for 4 hours to obtain hydroxylated titanium dioxide nanotubes; (3) 5g of hydroxylated titanium dioxide nanotubes were added to 60mL of N,N-dimethylformamide and dispersed for 15min. Then 3g of hyperbranched polymer was added and reacted at 105℃ for 5 hours. 20mL of water was added and stirred for 30min. The mixture was cooled to room temperature, centrifuged at 8000rpm for 15min, washed with water, and vacuum dried at 60℃ for 12 hours to obtain hyperbranched modified titanium dioxide nanotubes.

[0023] Preparation Example 2 Preparation of hyperbranched modified titanium dioxide nanotubes: (1) Take 5g of trimethylolpropane, 12g of mercaptopropionic acid and 0.15g of stannous octoate, and react at 90℃ for 4h under nitrogen protection; then add 8.5g of adipate dihydrazide and 0.1g of p-toluenesulfonic acid, heat to 110℃ and stir at 300rpm / min for 5h, and dry at 90℃ under vacuum of -0.095MPa for 2h to obtain hyperbranched polymer; (2) Take 10g of titanium dioxide nanotubes and add 150mL of water, sonicate for 20min and add 1.5g of sodium hydroxide. Stir, place in a 60℃ constant temperature water bath, stir magnetically for 1h, wash with water until neutral, and vacuum dry at 80℃ for 4h to obtain hydroxylated titanium dioxide nanotubes; (3) Take 6.8g of hydroxylated titanium dioxide nanotubes and add 60mL of N,N-dimethylformamide to disperse for 15min, then add 1.2g of hyperbranched polymer, react at 105℃ for 5h, add 20mL of water and stir for 30min, cool to room temperature, centrifuge at 8000rpm for 15min, wash with water, and vacuum dry at 60℃ for 12h to obtain hyperbranched modified titanium dioxide nanotubes.

[0024] Preparation Example 3 Preparation of hyperbranched modified titanium dioxide nanotubes: (1) Take 5g of trimethylolpropane, 12g of mercaptopropionic acid and 0.15g of stannous octoate, and react at 90℃ for 4h under nitrogen protection; then add 8.5g of adipate dihydrazide and 0.1g of p-toluenesulfonic acid, heat to 110℃ and stir at 300rpm / min for 5h, and dry at 90℃ under vacuum of -0.095MPa for 2h to obtain hyperbranched polymer; (2) Take 10g of titanium dioxide nanotubes and add 150mL of water, sonicate for 20min and add 1.5g of sodium hydroxide. Stir, place in a 60℃ constant temperature water bath, magnetically stir for 1h, wash with water until neutral, vacuum dry at 80℃ for 4h to obtain hydroxylated titanium dioxide nanotubes; (3) Take 4.2g of hydroxylated titanium dioxide nanotubes and add 60mL of N,N-dimethylformamide to disperse for 15min, then add 3.8g of hyperbranched polymer, react at 105℃ for 5h, add 20mL of water and stir for 30min, cool to room temperature, centrifuge at 8000rpm for 15min, wash with water, vacuum dry at 60℃ for 12h to obtain hyperbranched modified titanium dioxide nanotubes.

[0025] Preparation Example 4 Preparation of modified titanium dioxide nanotubes: 10g of titanium dioxide nanotubes were added to 150mL of water, sonicated for 20min, 1.5g of sodium hydroxide was added and stirred, and placed in a constant temperature water bath at 60℃. The mixture was magnetically stirred for 1h, washed with water until neutral, and vacuum dried at 80℃ for 4h to obtain hydroxylated titanium dioxide nanotubes.

[0026] Preparation Example 5 Preparation of borate-modified diethylenetriamine: 1.03 g of diethylenetriamine was added to 50 mL of ethanol and heated to 45 °C; 30 mL of ethanol containing 0.28 g of 3-carboxyphenylboronic acid and 0.4 g of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide was added, followed by 10 mL of 0.1 M MES buffer (pH 6.0), and the mixture was stirred for 6 h. The mixture was then distilled under reduced pressure, centrifuged, washed with water, and dried under vacuum at 60 °C for 8 h to obtain borate-modified diethylenetriamine.

[0027] Preparation Example 6 Preparation of quaternary ammonium salt modified polysulfone: Take 18g of polysulfone and add it to 80ml of... N,N-dimethylformamide, dehydrated by molecular sieve for 24 h, was heated to 60 °C and stirred at 200 rpm for 24 h under nitrogen protection. The mixture was then cooled to 45 °C, and 1 g of anhydrous K2CO3 was added and stirred for 10 min. 3.5 g of glycidyltrimethylammonium chloride was added dropwise, and the mixture was heated to 60 °C and stirred for 6 h. The mixture was then washed with water and dried under vacuum at 60 °C for 12 h to obtain quaternary ammonium salt modified polysulfone.

[0028] Example 1 A high-performance reverse osmosis membrane comprises the following steps: S1, weighing 15g of quaternary ammonium salt modified polysulfone, 75g of N,N-dimethylformamide, and 10g of polyvinylpyrrolidone obtained in Preparation Example 6, mixing the above raw materials, allowing them to stand, and then degassing and filtering to obtain a casting solution for later use; S2, using a pressure pump, uniformly spraying the casting solution onto a nonwoven fabric through a slit-type coating head, allowing it to stand for 3 seconds after coating, and then placing it in a water coagulation solution at a temperature of 10°C to allow the casting solution to form a membrane, obtaining a polysulfone support layer; S3, accurately weighing 2g of m-phenylenediamine and 0.5g of borate-modified diethylenetriamine obtained in Preparation Example 5, and adding 92.52g of... In water, after stirring, 1.5g of the hyperbranched modified titanium dioxide nanotubes prepared in Preparation Example 1 were added, followed by 2.8g of camphor sulfonic acid, 0.18g of sodium dodecyl sulfonate, and 0.5g of sodium hydroxide to obtain an aqueous solution. The aqueous solution was coated onto the polysulfone support layer obtained in step S2 through a slit coating head and dried. In step S4, 0.1g of trimesoyl chloride and 99.9g of n-heptane were accurately weighed and mixed to obtain an oil solution. The oil solution was coated onto the membrane in step S3 through a slit coating head for reaction, and then placed in an oven and dried at 80°C for 10min to obtain a high-performance reverse osmosis membrane.

[0029] Example 2 A high-performance reverse osmosis membrane comprises the following steps: S1, weighing 15g of quaternary ammonium salt modified polysulfone, 75g of N,N-dimethylformamide, and 10g of polyvinylpyrrolidone obtained in Preparation Example 6, mixing the above raw materials, allowing them to stand, and then degassing and filtering to obtain a casting solution for later use; S2, using a pressure pump, uniformly spraying the casting solution onto a nonwoven fabric through a slit-type coating head, allowing it to stand for 3 seconds after coating, and then placing it in a water coagulation solution at a temperature of 10°C to allow the casting solution to form a membrane, obtaining a polysulfone support layer; S3, accurately weighing 2g of m-phenylenediamine and 0.5g of borate-modified diethylenetriamine obtained in Preparation Example 5, and adding 92.52g of... In water, after stirring, add 1.5g of the hyperbranched modified titanium dioxide nanotubes prepared in Preparation Example 2, and then add 2.8g of camphor sulfonic acid, 0.18g of sodium dodecyl sulfonate, and 0.5g of sodium hydroxide in sequence to obtain an aqueous solution. Coat the aqueous solution onto the polysulfone support layer obtained in step S2 through a slit coating head and dry it. In step S4, accurately weigh 0.1g of trimesoyl chloride and 99.9g of n-heptane, mix them to obtain an oil phase solution, and coat the oil phase solution onto the membrane in step S3 through a slit coating head to react. Then place it in an oven and dry it at 80°C for 10min to obtain a high-performance reverse osmosis membrane.

[0030] Example 3 A high-performance reverse osmosis membrane comprises the following steps: S1, weighing 15g of quaternary ammonium salt modified polysulfone, 75g of N,N-dimethylformamide, and 10g of polyvinylpyrrolidone obtained in Preparation Example 6, mixing the above raw materials, allowing them to stand, and then degassing and filtering to obtain a casting solution for later use; S2, using a pressure pump, uniformly spraying the casting solution onto a nonwoven fabric through a slit-type coating head, allowing it to stand for 3 seconds after coating, and then placing it in a water coagulation solution at a temperature of 10°C to allow the casting solution to form a membrane, obtaining a polysulfone support layer; S3, accurately weighing 2g of m-phenylenediamine and 0.5g of borate-modified diethylenetriamine obtained in Preparation Example 5, and adding 92.52g of... In water, after stirring, 1.5g of the hyperbranched modified titanium dioxide nanotubes prepared in Preparation Example 3 were added, followed by 2.8g of camphor sulfonic acid, 0.18g of sodium dodecyl sulfonate, and 0.5g of sodium hydroxide to obtain an aqueous solution. The aqueous solution was coated onto the polysulfone support layer obtained in step S2 through a slit coating head and dried. In step S4, 0.1g of trimesoyl chloride and 99.9g of n-heptane were accurately weighed and mixed to obtain an oil solution. The oil solution was coated onto the membrane in step S3 through a slit coating head for reaction, and then placed in an oven and dried at 80°C for 10min to obtain a high-performance reverse osmosis membrane.

[0031] Example 4 A high-performance reverse osmosis membrane includes the following steps: S1, Weigh 15g of polysulfone, 75g of N,N-dimethylformamide, and 10g of polyvinylpyrrolidone, mix the above raw materials evenly and let stand, then degas and filter to obtain a casting solution for later use; S2, Using a pressure pump, uniformly spray the casting solution onto a non-woven fabric through a slit-type coating head, let stand for 3 seconds after coating, and place it in a water coagulation solution at a temperature of 10°C to allow the casting solution to form a membrane, obtaining a polysulfone support layer; S3, Accurately weigh 2g of m-phenylenediamine and 0.5g of borate-modified diethylenetriamine obtained in Preparation Example 5, add them to 92.52g of water, stir, and then... Add 1.5g of the hyperbranched modified titanium dioxide nanotubes prepared in Preparation Example 1, and then add 2.8g of camphor sulfonic acid, 0.18g of sodium dodecyl sulfonate and 0.5g of sodium hydroxide in sequence to obtain an aqueous solution. Coat the aqueous solution onto the polysulfone support layer obtained in step S2 through a slit coating head and dry it. In step S4, accurately weigh 0.1g of trimesoyl chloride and 99.9g of n-heptane, mix them to obtain an oil phase solution, and coat the oil phase solution onto the membrane in step S3 through a slit coating head to react. Then place it in an oven and dry it at 80°C for 10min to obtain a high-performance reverse osmosis membrane.

[0032] Comparative Example 1 A high-performance reverse osmosis membrane comprises the following steps: S1, weighing 15g of quaternary ammonium salt modified polysulfone, 75g of N,N-dimethylformamide, and 10g of polyvinylpyrrolidone obtained in Preparation Example 6, mixing the above raw materials, allowing them to stand, and then degassing and filtering to obtain a casting solution for later use; S2, using a pressure pump, uniformly spraying the casting solution onto a nonwoven fabric through a slit-type coating head, allowing it to stand for 3 seconds after coating, and then placing it in a water coagulation solution at a temperature of 10°C to allow the casting solution to form a membrane, obtaining a polysulfone support layer; S3, accurately weighing 2g of m-phenylenediamine and 0.5g of borate-modified diethylenetriamine obtained in Preparation Example 5, adding 92.5 Add 1.5g of the modified titanium dioxide nanotubes prepared in Preparation Example 4 to 2g of water, stir, and then add 2.8g of camphor sulfonic acid, 0.18g of sodium dodecyl sulfonate, and 0.5g of sodium hydroxide to obtain an aqueous solution. Coat the aqueous solution onto the polysulfone support layer obtained in step S2 through a slit coating head and dry it. In step S4, accurately weigh 0.1g of trimesoyl chloride and 99.9g of n-heptane, mix them to obtain an oil phase solution, and coat the oil phase solution onto the membrane in step S3 through a slit coating head to react. Then place it in an oven and dry it at 80°C for 10min to obtain a high-performance reverse osmosis membrane.

[0033] Comparative Example 2 A high-performance reverse osmosis membrane comprises the following steps: S1, weighing 15g of quaternary ammonium salt modified polysulfone, 75g of N,N-dimethylformamide, and 10g of polyvinylpyrrolidone obtained in Preparation Example 6, mixing the above raw materials, allowing them to stand, and then degassing and filtering to obtain a casting solution for later use; S2, using a pressure pump, uniformly spraying the casting solution onto a nonwoven fabric through a slit-type coating head, allowing it to stand for 3 seconds after coating, and then placing it in a water coagulation solution at a temperature of 10°C to allow the casting solution to form a membrane, obtaining a polysulfone support layer; S3, accurately weighing 2g of m-phenylenediamine and 0.5g of borate-modified diethylenetriamine obtained in Preparation Example 5, and adding... Add 1.5g of titanium dioxide nanotubes to 92.52g of water, stir, and then add 2.8g of camphor sulfonic acid, 0.18g of sodium dodecyl sulfonate, and 0.5g of sodium hydroxide in sequence to obtain an aqueous solution. Coat the aqueous solution onto the polysulfone support layer obtained in step S2 through a slit coating head and dry it. In step S4, accurately weigh 0.1g of trimesoyl chloride and 99.9g of n-heptane, mix them to obtain an oil phase solution, and coat the oil phase solution onto the membrane in step S3 through a slit coating head to react. Then place it in an oven and dry it at 80℃ for 10min to obtain a high-performance reverse osmosis membrane.

[0034] Comparative Example 3 A high-performance reverse osmosis membrane includes the following steps: S1, Weigh 15g of quaternary ammonium salt modified polysulfone, 75g of N,N-dimethylformamide, and 10g of polyvinylpyrrolidone obtained in Preparation Example 6, mix the above raw materials evenly and let stand, then degas and filter to obtain a casting solution for later use; S2, Using a pressure pump, uniformly spray the casting solution onto a nonwoven fabric through a slit-type coating head, let stand for 3 seconds after coating, and place it in a water coagulation solution at a temperature of 10°C to allow the casting solution to form a film, obtaining a polysulfone support layer; S3, Accurately weigh 2g of m-phenylenediamine and 0.5g of diethylenetriamine, add them to 92.52g of water, stir, and then... Add 1.5g of the hyperbranched modified titanium dioxide nanotubes prepared in Preparation Example 1, and then add 2.8g of camphor sulfonic acid, 0.18g of sodium dodecyl sulfonate and 0.5g of sodium hydroxide in sequence to obtain an aqueous solution. Coat the aqueous solution onto the polysulfone support layer obtained in step S2 through a slit coating head and dry it. In step S4, accurately weigh 0.1g of trimesoyl chloride and 99.9g of n-heptane, mix them to obtain an oil phase solution, and coat the oil phase solution onto the membrane in step S3 through a slit coating head to react. Then place it in an oven and dry it at 80°C for 10min to obtain a high-performance reverse osmosis membrane.

[0035] Comparative Example 4 A high-performance reverse osmosis membrane comprises the following steps: S1, weighing 15g of quaternary ammonium salt modified polysulfone, 75g of N,N-dimethylformamide, and 10g of polyvinylpyrrolidone obtained in Preparation Example 6, mixing the above raw materials, allowing them to stand, and then degassing and filtering to obtain a casting solution for later use; S2, using a pressure pump, uniformly spraying the casting solution onto a nonwoven fabric through a slit-type coating head, allowing it to stand for 3 seconds after coating, and then placing it in a water coagulation solution at a temperature of 10°C to allow the casting solution to form a membrane, obtaining a polysulfone support layer; S3, accurately weighing 2g of m-phenylenediamine and borate-modified diethylene obtained in Preparation Example 5. 2g of triamine was added to 92.52g of water and stirred. Then, 2.8g of camphor sulfonic acid, 0.18g of sodium dodecyl sulfonate, and 0.5g of sodium hydroxide were added sequentially to obtain an aqueous solution. The aqueous solution was coated onto the polysulfone support layer obtained in step S2 through a slit coating head and dried. In step S4, 0.1g of trimesoyl chloride and 99.9g of n-heptane were accurately weighed and mixed to obtain an oil solution. The oil solution was coated onto the membrane in step S3 through a slit coating head for reaction. Then, it was placed in an oven and dried at 80°C for 10 minutes to obtain a high-performance reverse osmosis membrane.

[0036] Comparative Example 5 A high-performance reverse osmosis membrane comprises the following steps: S1, weighing 15g of quaternary ammonium salt modified polysulfone, 75g of N,N-dimethylformamide, and 10g of polyvinylpyrrolidone obtained in Preparation Example 6, mixing the above raw materials, allowing them to stand, and then degassing and filtering to obtain a casting solution for later use; S2, using a pressure pump, uniformly spraying the casting solution onto a nonwoven fabric through a slit-type coating head, allowing it to stand for 3 seconds after coating, and then placing it in a water coagulation solution at a temperature of 10°C to allow the casting solution to form a membrane, obtaining a polysulfone support layer; S3, accurately weighing 2g of m-phenylenediamine and adding it to 92.52g of water, stirring, and then adding 2g of... The hyperbranched modified titanium dioxide nanotubes prepared in Example 1 were then sequentially supplemented with 2.8 g of camphor sulfonic acid, 0.18 g of sodium dodecyl sulfonate, and 0.5 g of sodium hydroxide to obtain an aqueous solution. The aqueous solution was then coated onto the polysulfone support layer obtained in step S2 using a slit coating head and dried. In step S4, 0.1 g of trimesoyl chloride and 99.9 g of n-heptane were accurately weighed and mixed to obtain an oil solution. The oil solution was then coated onto the membrane from step S3 using a slit coating head to carry out the reaction. The membrane was then placed in an oven and dried at 80 °C for 10 min to obtain a high-performance reverse osmosis membrane.

[0037] Performance testing Performance testing of high-performance reverse osmosis membranes in terms of water flux and desalination rate: The performance of reverse osmosis membranes prepared in the examples and comparative examples was tested at room temperature using a cross-flow flat sheet membrane performance evaluation device. The separation performance of the reverse osmosis membranes was evaluated according to GB / T32373 "Test Methods for Reverse Osmosis Membranes". The test solution was a 2000 ppm sodium chloride aqueous solution, the test pressure was 1.55 MPa, the pH was 7.0, and the test temperature was 25℃. After running under constant temperature and pressure for 30 minutes, a certain volume of permeate was taken, and the volume of permeate was measured over a certain time using a stopwatch and graduated cylinder. The conductivity of the permeate and feed water was also tested, and the water flux and desalination rate were calculated. The results are shown in Table 1. Water flux = permeate volume / (effective membrane area * test time), unit: L / (m²). 2 ﹒ h); Desalination rate = (1 - product water conductivity / influent water conductivity) * 100%; TOC removal rate test of high-performance reverse osmosis membrane: The TOC in the solution was prepared with 500 ppm isopropanol. After the membrane was run for 30 minutes, the permeate and feed water were collected and their TOC content was tested respectively. The membrane under test was installed in the test cell of the membrane performance evaluation instrument. The test temperature was 25℃ and the test pressure was 1.55 MPa. TOC removal rate = (feed water TOC value - permeate TOC value) / feed water TOC value * 100%. The results are shown in Table 1.

[0038] Table 1. Test results of separation performance of high-performance reverse osmosis membranes Referring to Table 1, and in conjunction with Examples 1-4 and Comparative Examples 1-6, the reverse osmosis membrane exhibits a high organic matter rejection rate and avoids problems such as filler loss and membrane fouling. In conjunction with Examples 1-3 and Comparative Examples 1-2, it can be seen that hyperbranching modification of titanium dioxide nanotubes introduces a hyperbranched structure with a three-dimensional spatial configuration and abundant terminal sites. Its active groups can bind small-molecule hydrophilic TOCs such as methanol and acetic acid in water through hydrogen bonding. Simultaneously, the borate groups can act as Lewis acid sites, forming stable and reversible coordination bonds with the hydroxyl, carboxyl, and amide groups of small-molecule TOCs, significantly enhancing the capture capacity of organic matter in water and further improving the overall TOC rejection rate.

[0039] As can be seen from Examples 1 and 4, in quaternary ammonium salt modified polysulfone, the hydrophilicity of the quaternary ammonium salt groups can improve the water wettability of the support layer and reduce the mass transfer resistance of water molecules. Together with the hydrophilic groups such as boric acid groups and hydroxyl groups in the polyamide layer, it can further optimize the overall water flux. The electrostatic adsorption of the support layer can pre-detain some large molecular TOC, reduce the retention burden of the polyamide separation layer, and promote the capture of small molecular TOC by the separation layer, thereby improving the total TOC removal efficiency.

[0040] As can be seen from Example 1 and Comparative Examples 4-5, the combined action of borate-based diethylenetriamine and hyperbranched titanium dioxide nanotubes in the preparation of reverse osmosis membranes synergistically improves membrane flux and TOC removal rate.

[0041] 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 high performance reverse osmosis membrane, characterized by: The polyamide separation layer comprises 1.5-3 parts of m-phenylenediamine, 0.5-1.5 parts of boronic acid group modified diethylene triamine, 1.5-3 parts of hyperbranched modified titanium dioxide nanotubes, 2.5-3 parts of pH adjuster, 0.18-0.5 parts of surfactant, 0.5-1.5 parts of acid acceptor, 0.5-1.5 parts of acyl chloride monomer and 99-108 parts of alkane solvent. The preparation method of the hyperbranched modified titanium dioxide nanotubes comprises: (1) taking trimethylolpropane, mercaptopropionic acid and stannous octoate, under nitrogen protection, heating to 80-90 DEG C, reacting for 3-5 h; then adding adipic acid dihydrazide and p-toluenesulfonic acid, reacting at 100-110 DEG C for 3-5 h to obtain a hyperbranched polymer; (2) taking hydroxylated titanium dioxide nanotubes, adding N,N-dimethylformamide and dispersing for 10-15 min, then adding the hyperbranched polymer, reacting at 100-115 DEG C for 4-5 h, cooling to room temperature, centrifuging, washing and drying to obtain the hyperbranched modified titanium dioxide nanotubes.

2. The high performance reverse osmosis membrane of claim 1, wherein: The mass ratio of the hyperbranched polymer to the hydroxylated titanium dioxide nanotubes is 1: (0.5-0.7).

3. The high performance reverse osmosis membrane of claim 2, wherein: The raw materials of the polyamide separation layer comprise 1.5-3 parts of m-phenylenediamine, 0.5-1.5 parts of boronic acid group modified diethylene triamine, 1.5-3 parts of hyperbranched modified titanium dioxide nanotubes, 2.5-3 parts of pH adjuster, 0.18-0.5 parts of surfactant, 0.5-1.5 parts of acid acceptor, 0.5-1.5 parts of acyl chloride monomer and 99-108 parts of alkane solvent.

4. The high performance reverse osmosis membrane of claim 1, wherein: The pH adjuster is one of camphorsulfonic acid and citric acid; the surfactant is one of sodium dodecyl sulfonate, sodium dodecyl sulfate and sodium dodecyl benzene sulfonate; and the acid acceptor is one of sodium hydroxide, sodium carbonate and trisodium phosphate.

5. The high performance reverse osmosis membrane of claim 1, wherein: The acyl chloride monomer comprises one or more of phthaloyl chloride, benzenesulfonyl chloride, 2,5-dichlorobenzenesulfonyl chloride, 2,5-dibromobenzenesulfonyl chloride, 3,4-dibromobenzenesulfonyl chloride, 1,3-benzenedisulfonyl chloride and trimesoyl chloride.

6. The high performance reverse osmosis membrane of claim 1, wherein: The alkane solvent is one or more of n-hexane, cyclohexane, ethylcyclohexane and n-heptane.

7. The high performance reverse osmosis membrane of claim 1, wherein: The preparation method comprises the following steps: S1, taking quaternary ammonium salt modified polysulfone, N,N-dimethylformamide and polyvinylpyrrolidone, uniformly mixing, standing, defoaming and filtering to obtain a casting solution, spraying the casting solution on non-woven fabric, placing in water coagulation liquid to form a film, and obtaining a polysulfone support layer; S2, taking m-phenylenediamine, boronic acid group modified diethylene triamine, hyperbranched modified titanium dioxide nanotubes, pH adjuster, surfactant and acid acceptor, adding them into water to obtain an aqueous solution, coating the aqueous solution on the polysulfone support layer, and drying; S3, taking acyl chloride monomer and alkane solvent, uniformly mixing to obtain an oil solution, coating the oil solution on the film in step S2, reacting, and drying to obtain a high-performance reverse osmosis membrane.

8. The high performance reverse osmosis membrane according to any one of claims 1 to 7, wherein: ​

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