Efficient anti-pollution polyamide reverse osmosis membrane as well as preparation method and application thereof

Abstract

The invention discloses an efficient anti-pollution polyamide reverse osmosis membrane as well as a preparation method and application thereof. The polyamide reverse osmosis membrane comprises a substrate layer, a porous support layer, a polyamide separation layer and a cross-linked polymer anti-pollution layer. Wherein the cross-linked polymer anti-pollution layer is an N-hydroxyethyl acrylamide-co-epoxy polymer / aldehyde cross-linked polymer, and the cross-linked polymer anti-pollution layer is connected with the polyamide separation layer through a chemical bond. According to the reverse osmosis membrane provided by the invention, the anti-pollution performance and the cleaning stability of the reverse osmosis membrane can be effectively improved, meanwhile, the scratch resistance of the membrane is also improved, and the reverse osmosis membrane plays a positive role in industrial stable production and element rolling of the reverse osmosis membrane.

Description

Technical Field

[0001] This invention relates to the field of reverse osmosis technology, and in particular to a high-efficiency anti-fouling polyamide reverse osmosis membrane, its preparation method, and its application. Background Technology

[0002] Currently, polyamide reverse osmosis membrane technology, as a highly efficient, affordable, and mainstream separation technology, is widely used in seawater desalination, brackish water desalination, industrial wastewater treatment, municipal sewage treatment, household water purification, and industrial pure water production. During the use of reverse osmosis membranes, membrane fouling occurs due to the deposition and adsorption of organic matter, as well as chemical interactions with the membrane surface during mechanical, physical, or filtration processes, leading to a reduction in membrane permeate flow. In certain industries, such as electronics, pharmaceuticals, and food, reverse osmosis membranes cannot be cleaned with acids and alkalis as regularly as those used in wastewater treatment or seawater desalination to remove residual contaminants and restore permeate flow. Therefore, developing a reverse osmosis membrane with low flux decline during operation, low frequency of acid and alkali cleaning, high permeate flow recovery rate after acid and alkali cleaning, and long service life is of great significance.

[0003] Poly(N-hydroxyethylacrylamide) is a novel hydrophilic antifouling polymer. Compared with traditional hydrophilic polymers such as polyethylene glycol, polyvinylpyrrolidone, and polyvinyl alcohol, it has the characteristics of strong hydration ability and good biocompatibility. It has shown great application potential in fields such as biofouling prevention and controlled drug release, and is considered to be one of the most promising antifouling materials.

[0004] Currently, there is relatively little research on the application of poly(N-hydroxyethylacrylamide) in the field of separation membranes. The research mainly focuses on the hydrophilic modification of ultrafiltration or microfiltration membranes. For example, Chinese invention patent CN115350603A discloses a method for first preparing a polyvinylidene fluoride support membrane with hydrophilic poly(N-hydroxyethylacrylamide) surface functionalization by immersion precipitation phase inversion method, and then preparing a polyamide composite nanofiltration membrane by interfacial polymerization.

[0005] Therefore, there is a need in the art to develop a method that can efficiently and conveniently bond poly(N-hydroxyethylacrylamide) to the surface of a reverse osmosis membrane with strong chemical bonds to form an antifouling layer. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention provides a simple and efficient antifouling polyamide reverse osmosis membrane suitable for continuous industrial production and its preparation method. This improves the antifouling performance and cleaning recovery performance of existing reverse osmosis membranes, while also enhancing the scratch resistance of the membrane. This has a positive effect on the stable industrial production of reverse osmosis membranes and the winding of components.

[0007] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a high-efficiency antifouling polyamide reverse osmosis membrane, comprising, in sequence, a substrate layer, a porous support layer, a polyamide separation layer, and a cross-linked polymer antifouling layer;

[0009] The polyamide separation layer is a cross-linked polymer formed by the interfacial polycondensation reaction of polyamines and polyacrylamide chlorides;

[0010] The cross-linked polymer antifouling layer is a polymer formed by the cross-linking reaction of N-hydroxyethylacrylamide-co-epoxy polymer and aldehyde (i.e., N-hydroxyethylacrylamide-co-epoxy polymer / aldehyde cross-linked polymer).

[0011] The applicant has discovered that during the reverse osmosis membrane element winding process, scratches can occur on the membrane surface due to compression or misalignment between the membrane and the feed water separator, resulting in a significant loss in the final desalination rate of the membrane element. Poly(N-hydroxyethylacrylamide) possesses good self-crosslinking properties, giving it excellent scratch resistance. Therefore, using poly(N-hydroxyethylacrylamide) as an antifouling layer in reverse osmosis membranes provides good protection and mitigation against membrane winding scratches. This application achieves this by strongly bonding poly(N-hydroxyethylacrylamide) to the reverse osmosis membrane surface with strong chemical bonds, maintaining its excellent antifouling and cleaning recovery properties, while also improving the membrane's scratch resistance, thus facilitating stable industrial production of reverse osmosis membranes and element winding.

[0012] In some embodiments, the substrate layer is made of materials including, but not limited to, one or a mixture of several of polyethylene terephthalate, propylene terephthalate, and butylene terephthalate.

[0013] More preferably, the base layer is polyethylene terephthalate nonwoven fabric.

[0014] In some embodiments, the porous support layer is a porous ultrafiltration membrane formed by coating polysulfone on a substrate layer, with a pore size ranging from 1 to 100 nm, preferably from 1 to 50 nm, and a thickness ranging from 20 to 150 μm, preferably from 30 to 80 μm.

[0015] In some embodiments, the polyamine of the polyamide separation layer is an aromatic amine or an aliphatic amine containing at least two primary amine groups; preferably, the aromatic amine includes, but is not limited to, any one or a mixture of several of phenylenediamine or phenylenediamine, 1,3,5-triaminobenzene bonded to the benzene ring at the ortho, meta, or para positions, and the aliphatic amine includes, but is not limited to, any one or a mixture of several of ethylenediamine, propylenediamine, and piperazine;

[0016] More preferably, the polyfunctional amine is m-phenylenediamine.

[0017] In some embodiments, the polyacrylamide separation layer contains polyacrylamide chlorides selected from aromatic and / or aliphatic polyacrylamide chlorides; preferably, the aromatic polyacrylamide chlorides include, but are not limited to, any one or a mixture of several of pyromellitic tricarboxylic acid chloride, terephthaloyl chloride, isophthaloyl chloride, and naphthiadicarboxylic acid chloride, and the aliphatic polyacrylamide chlorides include, but are not limited to, any one or a mixture of several of malonyl chloride, succinyl chloride, adipic acid chloride, and 1,4-cyclohexamethylenedicarboxylic acid chloride;

[0018] More preferably, the polyacrylamide chloride is pyromellitic trimethylolpropionate chloride.

[0019] In one embodiment, after the polyamide separation layer is constructed in situ on the membrane surface of the porous support layer, it is first moisturized with a glycerol solution, and then N-hydroxyethylacrylamide-co-epoxy polymer, aldehyde and catalyst are blended and coated on the moisturized polyamide separation layer surface to form an N-hydroxyethylacrylamide-co-epoxy polymer / aldehyde cross-linked polymer at high temperature, i.e., a cross-linked polymer antifouling layer.

[0020] In the research on polyamide reverse osmosis membranes, the inventors of this application unexpectedly discovered that by coating the moisturized polyamide separation layer with N-hydroxyethylacrylamide-co-epoxy polymer / aldehyde crosslinking polymer, the initial properties of the membrane, such as flux and desalination rate, did not decrease significantly, and it had more stable and long-lasting antifouling properties. At the same time, the scratch resistance of the membrane was improved.

[0021] The possible mechanism of action of the technical solution of this invention is analyzed as follows: Under the action of a catalyst, the N-hydroxyethylacrylamide-co-epoxy polymer and aldehyde form a hemiacetal cross-linked network antifouling layer structure. Simultaneously, the residual amino groups of the N-hydroxyethylacrylamide-co-epoxy polymer and the polyamide separation layer react under the action of a catalyst (mainly phenolic hydroxyl groups, carboxyl groups, or acids) to form β-hydroxyl structural connections. Because the N-hydroxyethylacrylamide-co-epoxy polymer / aldehyde cross-linked polymer antifouling layer contains a large number of hydrophilic groups, it avoids the significant reduction in initial flux that occurs with ordinary antifouling layers. More importantly, the antifouling layer is chemically bonded, and because it is a cross-linked structure, it is not easily detached and maintains high antifouling performance even after multiple acid and alkali cleanings. In addition, due to the good self-crosslinking properties of the N-hydroxyethylacrylamide polymer, the N-hydroxyethylacrylamide-co-epoxy polymer / aldehyde cross-linked polymer antifouling layer has good scratch resistance.

[0022] In some embodiments, the N-hydroxyethylacrylamide-co-epoxy polymer has a weight-average molecular weight range of 20,000 to 150,000 Da, preferably 30,000 to 80,000 Da.

[0023] In some embodiments, the N-hydroxyethylacrylamide-co-epoxy polymer is a copolymer synthesized by free radical copolymerization, wherein the monomers include N-hydroxyethylacrylamide and epoxy-containing monomers;

[0024] Preferably, the epoxy-containing monomer includes, but is not limited to, glycidyl methacrylate, ethyl methacrylate, 2-propionic acid-2-methyl-2-[2-(2-oxybenzoxy)ethoxy]ethyl ester, allyl glycidyl ether, and active allyl epoxy polyether, more preferably, any one or a mixture of allyl glycidyl ether and active allyl epoxy polyether;

[0025] In actual operation, the N-hydroxyethyl acrylamide and the epoxy-containing monomer can be fed in any positive ratio. Preferably, the mass ratio of the N-hydroxyethyl acrylamide and the epoxy-containing monomer is 95:5 to 75:25.

[0026] In some embodiments, the N-hydroxyethylacrylamide-co-epoxy polymer contains a chemical crosslinking agent, which includes any one or a mixture of several of trimethylolpropane trimethacrylate, ethylene glycol dimethacrylate, trimethylolpropane diallyl ether, triallyl isocyanate, and N,N'-methylenebisacrylamide, preferably N,N'-methylenebisacrylamide;

[0027] The amount of the chemical crosslinking agent is 0.01 to 1.0% of the total mass of N-hydroxyethyl acrylamide and epoxy-containing monomers, preferably 0.05 to 0.3%.

[0028] The free radical copolymerization method described above further includes the reaction synthesis of N-hydroxyethylacrylamide-co-epoxy polymer in the presence of an initiator, wherein the initiator includes any one or a mixture of several of the following: azobisisobutyramidine hydrochloride, azobisisobutyramidine imidazoline hydrochloride, azobisisobutyramidine imidazoline sulfate, azobisisobutyramidal acid, azobis(hydroxyethylimidazoline)propane hydrochloride, azobisisobutyramidine, azobis(1-imino-1-pyrrolidinyl-2-ethylpropyl) hydrochloride, azobis(N-2-carboxyethyl-2-methylpropanediamine) hydrate, azobis[2-methyl-N-(1,1-dihydroxymethyl-2-hydroxyethyl)propionamide], and azobis[2-methyl-N-(2-hydroxyethyl)propionamide], preferably azobisisobutyramidine hydrochloride and / or azobisisobutyramidine hydrochloride;

[0029] The amount of the initiator is 0.01 to 5.0% of the total mass of N-hydroxyethyl acrylamide and epoxy-containing monomers, preferably 0.5 to 2.0%.

[0030] The free radical copolymerization method described above also includes the reaction synthesis of N-hydroxyethylacrylamide-co-epoxy polymer in a solvent environment, wherein the solvent is selected from any one or a mixture of several of water, methanol, ethanol, isopropanol, N-methylpyrrolidone, N,N-dimethylformamide, dimethylacetamide, and dimethyl sulfoxide, preferably water;

[0031] The amount of solvent used accounts for 20-99% of the total mass of the reaction system, more preferably 50-90%, and the present invention does not make any special limitation thereto.

[0032] The free radical copolymerization method described above is a known process in the prior art. The relevant operations and process conditions in the preparation method of this invention, as well as the apparatus used, can all be carried out using conventional methods in the art, and there are no particular restrictions. Those skilled in the art can optimize the process based on existing known processes according to actual needs, for example:

[0033] The free radical copolymerization method described herein has a reaction temperature of 20–80°C, preferably 40–70°C, a reaction time of 0.5–24 hours, preferably 4–8 hours, and a reaction pH controlled at 5–9, preferably 5–7.

[0034] In some embodiments, the aldehyde raw material of the N-hydroxyethylacrylamide-co-epoxy polymer / aldehyde crosslinking polymer includes any one or a mixture of several of the following: glyoxal, glutaraldehyde, adipaldehyde, isophthalaldehyde, 5-hydroxyisophthalaldehyde, 2,5-dihydroxyisophthalaldehyde, 2,4-dihydroxyisophthalaldehyde, 2,4-dicarboxymethylpyrogallol, terephthalaldehyde, 2,6-dihydroxy-1,4-phenylenedialdehyde, pyromellitic acid, 2-hydroxy-1,3,5-phenylenedialdehyde, 2,4-dihydroxy-1,3,5-pyromellitic acid, and 2,4,6-tricarboxymethylpyrogallol, preferably any one or a mixture of several of the following: glutaraldehyde, isophthalaldehyde, terephthalaldehyde, and pyromellitic acid.

[0035] In some embodiments, the N-hydroxyethylacrylamide-co-epoxy polymer / aldehyde crosslinking polymer needs to be reacted under catalytic conditions. The catalyst is selected from any one or a mixture of several of hydrochloric acid, sulfuric acid, phosphoric acid, 2,4,6-tris(dimethylaminomethyl)phenol, phenol, resorcinol, pyrogallol, acetic acid, and polyacrylic acid, preferably any one or a mixture of several of 2,4,6-tris(dimethylaminomethyl)phenol and polyacrylic acid.

[0036] Secondly, the present invention provides a method for preparing the above-mentioned high-efficiency antifouling polyamide reverse osmosis membrane, which can be prepared by combining and screening raw materials and conditions based on conventional processes in the field, according to the actual required structure.

[0037] Specifically, a method for preparing a high-efficiency anti-fouling polyamide reverse osmosis membrane includes the following steps:

[0038] S1: Obtain a polysulfone porous support layer on the surface of the polyester substrate;

[0039] S2: Immerse the polysulfone porous support layer in an aqueous solution containing polyamine and additives, leave it for a period of time, and then remove the residual aqueous solution from the surface.

[0040] S3: The surface of the polysulfone porous support layer is brought into contact with an organic phase solution containing polyacrylamide chloride to carry out an interfacial polymerization reaction. After reacting for a period of time, the residual organic phase solution on the surface is removed, followed by heat treatment, and then water washing until the membrane surface is hydrophilic and free of droplet aggregation, forming a polyamide separation layer.

[0041] S4: Soak the above membrane in a glycerol solution for a period of time, then remove the excess glycerol solution. If compressed air or nitrogen air knife is used to blow the front and back of the membrane, a moisturized polyamide separation layer is formed.

[0042] S5: After moisturizing, coat the surface of the polyamide separation layer with a mixed solution of N-hydroxyethylacrylamide-co-epoxy polymer, aldehyde and catalyst, remove the excess mixed solution, such as by rolling it off with a pressure roller, and then heat treat it for a period of time (such as oven treatment) to obtain the high-efficiency anti-fouling polyamide reverse osmosis membrane.

[0043] In the preparation method of this invention, the raw material selection listed above can be referred to. For other related operations and process conditions, as well as the equipment used, conventional selections in the art can be adopted, and there are no particular restrictions. Those skilled in the art can optimize the process based on existing technology and known processes according to actual needs. Specifically, for example, the conditions listed in the following embodiments of this invention can be used:

[0044] In some implementations, the preparation of the substrate layer and the porous support layer in step S1 can be carried out with reference to existing technologies. In a specific embodiment, for example, if the substrate is made of polyethylene terephthalate nonwoven fabric, the pore size of the porous support layer is in the range of 1–100 nm, preferably 1–50 nm; and its thickness is in the range of 20–150 μm, preferably 30–80 μm.

[0045] In some embodiments, the concentration of the polyamine in the aqueous solution described in step S2 is 0.5 to 10.0 wt%, preferably 1.0 to 5.0 wt%.

[0046] Preferably, the concentration of the additive in the aqueous solution is 1.0 to 20.0 wt%.

[0047] In some preferred embodiments, the pH of the aqueous solution is 9.0 to 12.0.

[0048] In one specific embodiment, the aqueous solution contains an additive, which is an acid receiver. The acid receiver includes a weak base, or a buffer pair composed of a weak base and an acid, or any one or a mixture of several of the following: alkali metal hydroxides, carbonates and bicarbonates, quaternary ammonium base organic compounds, etc.

[0049] Preferably, the weak base is selected from triethylamine and sodium phosphate, or a mixture of several of these; the buffer pair formed by the weak base and acid is selected from triethylamine hydrochloride and triethylamine camphor sulfonate, or a mixture of several of these; the alkali metal hydroxide, carbonate, and bicarbonate are selected from sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate, or a mixture of several of these; and the quaternary ammonium base organic compound is selected from tetramethylammonium hydroxide and tetraethylammonium hydroxide, or a mixture of several of these.

[0050] More preferably, the acid receiver is a buffer pair composed of a weak base and an acid, and more preferably triethylamine camphor sulfonate.

[0051] In a preferred embodiment, the aqueous solution contains 1.1–3.5 wt% triethylamine and 2.3–6.5 wt% camphorsulfonic acid, which together form an acid receiver.

[0052] In some implementations, the dwell time described in step S2 is 10 to 120 seconds.

[0053] In some embodiments, the concentration of polyacrylamide chloride in the organic phase solution described in step S3 is 0.01–1.0 wt%, preferably 0.05–0.5 wt%.

[0054] In some embodiments, the solvent in the organic phase solution described in step S3 is selected from any one or a mixture of several of n-hexane, cyclohexane, n-heptane, n-decane, isoalkanes Isopar G, and isoalkanes Isopar L, preferably any one or a mixture of several of n-hexane, cyclohexane, and isoalkanes Isopar G.

[0055] In some embodiments, the interfacial polymerization reaction described in step S3 is carried out at a temperature of 10–50°C, preferably 15–35°C, for a time of 10–60 seconds, preferably 30–60 seconds.

[0056] In some embodiments, the heat treatment in step S3 is performed at a temperature of 50–120°C, preferably 60–100°C, for a time of 3–10 minutes, preferably 3–5 minutes.

[0057] In some embodiments, the glycerol solution soaking in step S4 has a concentration of 1-20 wt%, preferably 2-10 wt%, a temperature of 40-100°C, preferably 50-70°C, and a time of 10-60 seconds, preferably 15-45 seconds.

[0058] Steps S1, S2, S3, and S4 described in this invention can all be obtained by using existing technology or by adjusting existing technology, and this invention does not impose any special limitations.

[0059] In some embodiments, the solvent for the N-hydroxyethylacrylamide-co-epoxy polymer, aldehyde, and catalyst mixture solution described in step S5 is water.

[0060] In some embodiments, the concentration of N-hydroxyethylacrylamide-co-epoxy polymer in the mixed solution described in step S5 is 0.01 to 5 wt%, more preferably 0.1 to 1 wt%.

[0061] In some embodiments, the concentration of aldehyde in the mixed solution described in step S5 is 0.01 to 1 wt%, more preferably 0.05 to 0.5 wt%.

[0062] In some embodiments, the concentration of the catalyst in the mixed solution described in step S5 is 0.005 to 0.5 wt%, more preferably 0.01 to 0.1 wt%.

[0063] In some embodiments, the heat treatment described in step S5 is performed at a temperature of 40–100°C, more preferably 60–80°C, for a time of 1–10 minutes, preferably 3–5 minutes.

[0064] The antifouling polyamide reverse osmosis membrane prepared by the method described in this invention has advantages such as low flux loss, high desalination rate, and antifouling. Specifically, the flux loss is less than 20%, the desalination rate can be as high as 99.0% or more, the acid and alkali cleaning recovery rate is high (it can be recovered to more than 95%, or even more than 99%), and the scratch resistance is improved.

[0065] Thirdly, the present invention also provides the use of the above-mentioned high-efficiency anti-fouling polyamide reverse osmosis membrane.

[0066] The use of a high-efficiency antifouling polyamide reverse osmosis membrane, wherein the reverse osmosis membrane is prepared by the method described above, or is the reverse osmosis membrane described above, and the reverse osmosis membrane is used in a water treatment assembly or water treatment method.

[0067] The water treatment component can be any component or device that can be applied to a water treatment process and is equipped with the reverse osmosis membrane of the present invention, including components or devices used in the preparation of such components or devices; the component can be, for example, a spiral wound membrane component and a disc tube flat sheet membrane component, or a household / commercial reverse osmosis water purifier, an industrial boiler feedwater reverse osmosis pure water device, an industrial wastewater reuse reverse osmosis device, etc.; the water treatment method can be, for example, brackish water wastewater reuse, drinking water production, pure water production, etc.

[0068] Compared with the prior art, the beneficial effects of the present invention are reflected in:

[0069] 1) This invention provides a high-efficiency antifouling polyamide reverse osmosis membrane with low flux loss and high desalination rate, while also maintaining stable and long-lasting antifouling performance.

[0070] 2) The antifouling layer of the polyamide reverse osmosis membrane of the present invention has a chemical cross-linked structure and is connected to the polyamide layer by chemical bonds, making its structure more stable. At the same time, the cross-linked polymer has a hydrophilic structure, which can maintain high antifouling performance after repeated acid and alkali washing. In addition, the chemical cross-linked structure improves the scratch resistance of the reverse osmosis membrane.

[0071] 3) The hydrophilic polymer in the polyamide reverse osmosis membrane of this invention is synthesized using a free radical copolymerization reaction with water as the solvent. The synthesis process is mild and pollution-free, requiring no separation or purification process, making it simple to operate and low in production cost. Furthermore, the antifouling layer coating process of this cross-linked polymer requires no modification to the existing process, facilitating industrial production. Attached Figure Description

[0072] Figure 1 This is a schematic diagram of the equipment used for scratch resistance testing according to the present invention. Detailed Implementation

[0073] To better understand the technical solution of the present invention, the following embodiments will further illustrate the method provided by the present invention. However, the present invention is not limited to the listed embodiments, but should also include any other known modifications within the scope of the claims of the present invention.

[0074] A high-efficiency antifouling polyamide reverse osmosis membrane, comprising, in sequence, a polyester substrate layer, a polysulfone porous support layer, a polyamide separation layer, and a cross-linked polymer antifouling layer.

[0075] The high-efficiency antifouling polyamide reverse osmosis membrane of the present invention comprises a polysulfone porous support layer formed on the surface of a polyester substrate layer as a polysulfone ultrafiltration membrane layer. The preparation of the polysulfone ultrafiltration support layer can be carried out using techniques known in the art, and no limitation is made thereto.

[0076] In a preferred embodiment, the pore size of the polysulfone porous support layer ranges from 1 to 100 nm, preferably from 1 to 50 nm; its thickness ranges from 20 to 150 μm, preferably from 30 to 80 μm; specifically, the pore size can be 1 nm, 10 nm, 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, or any combination thereof; the thickness can be 20 μm, 40 μm, 60 μm, 80 μm, 100 μm, 120 μm, 140 μm, 150 μm, or any combination thereof.

[0077] In a preferred embodiment, the polymer solution for preparing the polysulfone porous support layer may contain 15.0–20.0 wt% polysulfone. These components are dissolved in a polar solvent to obtain a polysulfone casting solution. Specifically, the concentration of polysulfone resin in the polymer solution may be 15.0 wt%, 15.4 wt%, 16.0 wt%, 16.5 wt%, 17.0 wt%, 17.5 wt%, 18.0 wt%, 18.5 wt%, 19.0 wt%, 19.5 wt%, 20.0 wt%, or any range thereof. The filtered and degassed polysulfone casting solution is then coated onto the surface of a polyester substrate (e.g., polyethylene terephthalate nonwoven fabric). The substrate is then placed in a gel bath for phase inversion to form a membrane. After washing, a polysulfone ultrafiltration support layer is obtained. The polar solvent preferably includes one or more of N,N-dimethylformamide, N,N-dimethylacetamide, or N-methylpyrrolidone.

[0078] The polyamide separation layer of the present invention can be prepared using existing well-known techniques in the art, and is not particularly limited thereto. In a preferred embodiment, the polyamide separation layer is a cross-linked aromatic polyamide primary layer with a three-dimensional network structure formed by interfacial polycondensation of a polyamine (e.g., m-phenylenediamine) and a polyacrylamide chloride (e.g., trimesoyl pyromellitic chloride).

[0079] The cross-linked polymer antifouling layer of the present invention is prepared by a co-coating method, wherein N-hydroxyethylacrylamide-co-epoxy polymer, aldehyde and catalyst are co-coated onto the surface of a moisturized polyamide separation layer, and after heat treatment, a high-efficiency antifouling polyamide reverse osmosis membrane is obtained.

[0080] A method for preparing a high-efficiency anti-fouling polyamide reverse osmosis membrane includes the following steps:

[0081] S1: Obtain a polysulfone porous support layer on the surface of the polyester substrate;

[0082] S2: Immerse the polysulfone porous support layer in an aqueous solution containing polyamine and additives, leave it for a period of time, and then remove the residual aqueous solution from the surface.

[0083] S3: The surface of the polysulfone porous support layer is brought into contact with an organic phase solution containing polyacrylamide chloride to carry out an interfacial polymerization reaction. After reacting for a period of time, the residual organic phase solution on the surface is removed, followed by heat treatment, and then water washing until the membrane surface is hydrophilic and free of droplet aggregation, forming a polyamide separation layer.

[0084] S4: Soak the above membrane in a glycerol solution for a period of time, and then use compressed air or nitrogen air knife to blow the front and back of the membrane to remove excess glycerol solution and form a moisturized polyamide separation layer.

[0085] S5: After moisturizing, the surface of the polyamide separation layer is coated with a mixed solution of N-hydroxyethylacrylamide-co-epoxy polymer, aldehyde and catalyst. The excess mixed solution is removed by using a pressure roller, and then the membrane is placed in an oven for heat treatment for a period of time to obtain the high-efficiency anti-fouling polyamide reverse osmosis membrane.

[0086] In the preparation method of the present invention, the substrate layer with a surface covered by a polysulfone porous support layer in step S1 can be prepared by referring to the methods listed above. For other raw material selection, related operations and process conditions, and the equipment used, the corresponding conventional selections in the field can be adopted. There are no special restrictions. Those skilled in the art can optimize the process based on existing technology and known processes according to actual needs. The present invention will not elaborate further here.

[0087] The polyamide separation layer of the present invention is a cross-linked polymer formed by interfacial polyamine and polyacryl chloride through interfacial polycondensation.

[0088] In a preferred embodiment, the polyamine in step S2 is an aromatic amine or an aliphatic amine containing at least two primary amine groups; preferably, the aromatic amine includes, but is not limited to, any one or a mixture of several of phenylenediamine or phenylenediamine, and 1,3,5-triaminobenzene bonded to the benzene ring at the ortho, meta, and para positions; the aliphatic amine includes, but is not limited to, any one or a mixture of several of ethylenediamine, propylenediamine, and piperazine; more preferably, the polyfunctional amine is m-phenylenediamine;

[0089] In the aqueous solution, the concentration of the polyamine is 0.5 to 10.0 wt%, preferably 1.0 to 5.0 wt%; specifically, the concentration of the polyamine can be 0.5 wt%, 1.0 wt%, 2.0 wt%, 3.0 wt%, 4.0 wt%, 5.0 wt%, 6.0 wt%, 7.0 wt%, 8.0 wt%, 9.0 wt%, 10.0 wt%, or a range consisting of any two of these.

[0090] In a preferred embodiment, the aqueous solution in step S2 contains an additive, which is an acid receiver. The acid receiver is selected from a weak base, a buffer pair composed of a weak base and an acid, or any one or a mixture of several of alkali metal hydroxides, carbonates and bicarbonates, and quaternary ammonium base organic compounds. Preferably, the weak base is selected from any one or a mixture of several of triethylamine and sodium phosphate; the buffer pair composed of the weak base and the acid is selected from any one or a mixture of several of triethylamine hydrochloride and triethylamine camphor sulfonate; the alkali metal hydroxides, carbonates and bicarbonates are selected from any one or a mixture of several of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, and potassium bicarbonate; the quaternary ammonium base organic compounds are selected from any one or a mixture of several of tetramethylammonium hydroxide and tetraethylammonium hydroxide; more preferably, the acid receiver is triethylamine camphor sulfonate.

[0091] In the aqueous solution, the concentration of the additive is 1.0 to 20.0 wt%, including but not limited to 1.0 wt%, 3.0 wt%, 5.0 wt%, 7.0 wt%, 9.0 wt%, 10.0 wt%, 12.0 wt%, 14.0 wt%, 16.0 wt%, 18.0 wt%, 20.0 wt%, or any combination thereof, and the pH of the aqueous solution is controlled to be 9.0 to 12.0, including but not limited to 9.0, 9.5, 10.0, 10.5, 11.0, 11.5, 12.0, or any combination thereof. Preferably, the aqueous solution contains 1.1–3.5 wt% triethylamine and 2.3–6.5 wt% camphor sulfonic acid, which form a buffer for triethylamine camphor sulfonate. Specifically, the concentration of triethylamine can be 1.1 wt%, 1.3 wt%, 1.5 wt%, 1.7 wt%, 2.0 wt%, 2.3 wt%, 2.5 wt%, 2.8 wt%, 3.0 wt%, 3.2 wt%, 3.5 wt%, or any two of these concentrations. The concentration of camphor sulfonic acid can be 2.3 wt%, 2.5 wt%, 2.8 wt%, 3.0 wt%, 3.3 wt%, 3.5 wt%, 3.8 wt%, 4.0 wt%, 4.3 wt%, 4.5 wt%, 4.8 wt%, 5.0 wt%, 5.3 wt%, 5.5 wt%, 5.8 wt%, 6.0 wt%, 6.3 wt%, 6.5 wt%, or any combination thereof.

[0092] In a preferred embodiment, the polysulfone porous support layer described in step S2 is in contact with the aqueous solution and remains there for a period of time, which is 10 to 120 seconds, preferably 30 to 60 seconds; the residence temperature can be room temperature, for example, 10 to 50°C, preferably 15 to 35°C; specifically, the residence time can be 10 seconds, 20 seconds, 30 seconds, 40 seconds, 50 seconds, 60 seconds, 70 seconds, 80 seconds, 90 seconds, 100 seconds, 110 seconds, 120 seconds or any combination thereof, and the residence temperature can be 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C or any combination thereof.

[0093] In a preferred embodiment, the polyacryl chloride in step S3 is selected from aromatic and / or aliphatic polyacryl chlorides; preferably, the aromatic polyacryl chloride includes, but is not limited to, any one or a mixture of several of pyromellitic tricarboxylic acid chloride, terephthaloyl chloride, isophthaloyl chloride, and naphthiadicarboxylic acid chloride, and the aliphatic polyacryl chloride includes, but is not limited to, any one or a mixture of several of malonyl chloride, succinyl chloride, adipyl chloride, and 1,4-cyclohexanediol chloride; more preferably, the polyacryl chloride is pyromellitic tricarboxylic acid chloride;

[0094] In the organic phase solution, the concentration of polyacrylamide chloride is 0.01 to 1.0 wt%, including but not limited to 0.01 wt%, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1.0 wt%, or any combination thereof, preferably 0.05 to 0.5 wt%.

[0095] In a preferred embodiment, the solvent in the organic phase solution described in step S3 is selected from any one or a mixture of several of n-hexane, cyclohexane, n-heptane, n-decane, isoalkanes Isopar G, and isoalkanes Isopar L, preferably any one or a mixture of several of n-hexane, cyclohexane, and isoalkanes Isopar G.

[0096] In a preferred embodiment, step S3 involves contacting the polysulfone porous support layer with an organic phase solution to perform an interfacial polymerization reaction. The reaction temperature is 10–50°C, preferably 15–35°C, and the reaction time is 10–60 seconds, preferably 30–60 seconds. Specifically, the temperature can be 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, or any combination thereof, and the time can be 10 seconds, 15 seconds, 20 seconds, 25 seconds, 30 seconds, 35 seconds, 40 seconds, 45 seconds, 50 seconds, 55 seconds, 60 seconds, or any combination thereof.

[0097] In a preferred embodiment, the heat treatment in step S3 is performed at a temperature of 50–120°C, preferably 60–100°C, for a time of 3–10 minutes, preferably 3–5 minutes. Specifically, the temperature can be 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, or any combination thereof, and the time can be 3 minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes, or any combination thereof.

[0098] The crosslinked polymer of the present invention is a crosslinked polymer formed by N-hydroxyethylacrylamide-co-epoxy polymer and aldehyde under the action of a catalyst and at high temperature.

[0099] In a preferred embodiment, the N-hydroxyethylacrylamide-co-epoxy polymer described in step S5 has a weight-average molecular weight range of 20,000 to 150,000 Da, preferably 30,000 to 80,000 Da; specifically, the weight-average molecular weight can be 20,000 Da, 30,000 Da, 40,000 Da, 50,000 Da, 60,000 Da, 70,000 Da, 80,000 Da, 90,000 Da, 100,000 Da, 110,000 Da, 120,000 Da, 130,000 Da, 140,000 Da, 150,000 Da, or a range consisting of any two of these.

[0100] In a preferred embodiment, the N-hydroxyethylacrylamide-co-epoxy polymer in step S5 is a copolymer synthesized by free radical copolymerization, and the monomers include N-hydroxyethylacrylamide and epoxy-containing monomers.

[0101] Preferably, the epoxy-containing monomer includes, but is not limited to, glycidyl methacrylate, ethyl methacrylate, 2-propionic acid-2-methyl-2-[2-(2-oxybenzoxy)ethoxy]ethyl ester, allyl glycidyl ether, and active allyl epoxy polyether, more preferably, any one or a mixture of allyl glycidyl ether and active allyl epoxy polyether;

[0102] In actual operation, the N-hydroxyethyl acrylamide and the epoxy-containing monomer can be fed in any positive ratio. Preferably, the mass ratio of the N-hydroxyethyl acrylamide and the epoxy-containing monomer is 95:5 to 75:25, including but not limited to 95:5, 90:10, 85:15, 80:20, 75:25 or any range thereof.

[0103] In actual operation, the N-hydroxyethylacrylamide-co-epoxy polymer contains a chemical crosslinking agent selected from any one or a mixture of several of trimethylolpropane trimethacrylate, ethylene glycol dimethacrylate, trimethylolpropane diallyl ether, triallyl isocyanate, and N,N'-methylenebisacrylamide, preferably N,N'-methylenebisacrylamide; the amount of chemical crosslinking agent is 0.01 to 1.0 wt% of the total mass of N-hydroxyethylacrylamide and epoxy-containing monomers, including but not limited to 0.01 wt%, 0.05 wt%, 0.1 wt%, 0.2 wt%, 0.5 wt%, 0.7 wt%, 1.0 wt%, or any combination thereof, preferably 0.05 to 0.3 wt%.

[0104] The free radical copolymerization method described above involves reacting in the presence of an initiator to synthesize N-hydroxyethylacrylamide-co-epoxy polymer. The initiator is selected from any one or a mixture of several of the following: azobisisobutyramidine hydrochloride, azobisisobutyramidine imidazoline hydrochloride, azobisisobutyramidine imidazoline sulfate, azobiscyanopentanoic acid, azobis(hydroxyethyl)imidazoline, azobis(1-imino-1-pyrrolidinyl-2-ethylpropyl) hydrochloride, azobis(N-2-carboxyethyl-2-methylpropanediamine) hydrate, azobis[2-methyl-N-(1,1-dihydroxymethyl-2-hydroxyethyl)propionamide], and azobis[2-methyl-N-(2-hydroxyethyl)propionamide]. Preferably, azobisisobutyramidine hydrochloride or azobisisobutyramidine imidazoline hydrochloride is selected.

[0105] The initiator is used in an amount of 0.01 to 5.0% of the total mass of N-hydroxyethyl acrylamide and epoxy-containing monomers, including but not limited to 0.01 wt%, 0.1 wt%, 1.0 wt%, 1.5 wt%, 2.0 wt%, 2.5 wt%, 3.0 wt%, 3.5 wt%, 4.0 wt%, 4.5 wt%, 5.0 wt%, or any combination thereof, preferably 0.5 to 2.0%.

[0106] The free radical copolymerization method involves reacting and synthesizing N-hydroxyethylacrylamide-co-epoxy polymer in a solvent environment. The solvent is selected from any one or a mixture of several of water, methanol, ethanol, isopropanol, N-methylpyrrolidone, N,N-dimethylformamide, dimethylacetamide, and dimethyl sulfoxide, preferably water.

[0107] The amount of solvent used accounts for 20-99% of the total mass of the reaction system, including but not limited to 20wt%, 30wt%, 40wt%, 50wt%, 60wt%, 70wt%, 80wt%, 90wt%, 99wt%, or any combination thereof, preferably 50-90%.

[0108] In a preferred embodiment, the glycerol solution soaking in step S4 has a concentration of 1-20 wt%, preferably 2-10 wt%, a temperature of 40-100°C, preferably 50-70°C, and a time of 10-60 seconds, preferably 15-45 seconds. Specifically, the concentration can be 1 wt%, 2 wt%, 5 wt%, 10 wt%, 15 wt%, 20 wt%, or any combination thereof; the temperature can be 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, or any combination thereof; and the time can be 10 seconds, 20 seconds, 30 seconds, 40 seconds, 50 seconds, 60 seconds, or any combination thereof.

[0109] The free radical copolymerization method described above is a known process in the prior art. The relevant operations and process conditions in the preparation method of this invention, as well as the apparatus used, can all be carried out using conventional methods in the art, and there are no particular restrictions. Those skilled in the art can optimize the process based on existing known processes according to actual needs, for example:

[0110] The free radical copolymerization method described herein has a reaction temperature of 20–80°C, preferably 40–70°C, a reaction time of 0.5–24 hours, preferably 4–8 hours, and a reaction pH controlled at 5–9, preferably 5–7. Specifically, the reaction temperature can be 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, or any combination thereof; the reaction time can be 0.5 hours, 1 hour, 2 hours, 4 hours, 8 hours, 16 hours, 24 hours, or any combination thereof; and the reaction pH can be 5, 6, 7, 8, 9, or any combination thereof.

[0111] In a preferred embodiment, the solvent of the N-hydroxyethylacrylamide-co-epoxy polymer / aldehyde / catalyst mixed solution in step S5 is water, and the concentration of the N-hydroxyethylacrylamide-co-epoxy polymer is 0.01 to 5 wt%, including but not limited to 0.01 wt%, 0.1 wt%, 1.0 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, or any combination thereof, preferably 0.1 to 1 wt%.

[0112] In a preferred embodiment, the aldehyde in step S5 is selected from any one or a mixture of several of glyoxal, glutaraldehyde, adipaldehyde, isophthalaldehyde, 5-hydroxyisophthalaldehyde, 2,5-dihydroxyisophthalaldehyde, 2,4-dihydroxyisophthalaldehyde, 2,4-dicarboxymethylpyrogallol, terephthalaldehyde, 2,6-dihydroxy-1,4-phenylenedialdehyde, pyromellitic acid, 2-hydroxy-1,3,5-phenylenedialdehyde, 2,4-dihydroxy-1,3,5-pyromellitic acid, and 2,4,6-tricarboxymethylpyromellitic acid, preferably any one or a mixture of several of glutaraldehyde, isophthalaldehyde, terephthalaldehyde, and pyromellitic acid.

[0113] The aldehyde concentration is 0.01 to 1 wt%, including but not limited to 0.01 wt%, 0.05 wt%, 0.1 wt%, 0.3 wt%, 0.5 wt%, 1 wt%, or any combination thereof, preferably 0.05 to 0.5 wt%.

[0114] In a preferred embodiment, the catalyst in step S5 is selected from any one or a mixture of several of hydrochloric acid, sulfuric acid, phosphoric acid, 2,4,6-tris(dimethylaminomethyl)phenol, phenol, resorcinol, pyrogallol, acetic acid, and polyacrylic acid, preferably any one or a mixture of several of 2,4,6-tris(dimethylaminomethyl)phenol and polyacrylic acid, wherein the weight-average molecular weight of the polyacrylic acid is in the range of 1,000 to 1,250,000 Da, preferably 2,000 to 100,000 Da.

[0115] The catalyst concentration is 0.005 to 0.5 wt%, including but not limited to 0.005 wt%, 0.01 wt%, 0.05 wt%, 0.1 wt%, 0.2 wt%, 0.5 wt%, or any combination thereof, preferably 0.01 to 0.1 wt%.

[0116] In some embodiments, the heat treatment described in step S5 involves a reaction temperature of 40–100°C, preferably 60–80°C, and a reaction time of 1–10 minutes, preferably 3–5 minutes. Specifically, the reaction temperature can be 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, or a range thereof, and the reaction time can be 1 minute, 3 minutes, 5 minutes, 7 minutes, 10 minutes, or a range thereof.

[0117] Main raw material sources

[0118] Unless otherwise specified, the raw materials used in the following examples or comparative examples are all commercially available conventional raw materials. The main raw material information is shown in Table 1 below.

[0119] Table 1: Information on Main Raw Materials

[0120]

[0121]

[0122] Main testing methods

[0123] The analytical methods used or potentially used in the embodiments or comparative examples of this invention are described below:

[0124] 1. Evaluation of desalination rate and permeability

[0125] Desalination rate and permeate flux are two important parameters for evaluating the separation performance of reverse osmosis membranes. This invention evaluates the separation performance of reverse osmosis membranes according to GB / T32373-2015 "Test Methods for Reverse Osmosis Membranes".

[0126] Desalination rate (R) is defined as: under certain operating conditions, the salt concentration (C) of the feed solution... f ) and the salt concentration in the permeate (C p The difference between the two is then divided by the feed solution salt concentration (C). f ), as in formula (1).

[0127]

[0128] Permeation flux is defined as the volume of water that permeates through a unit membrane area per unit time under certain operating conditions, and its unit is L·m. -2 ·h -1 .

[0129] The operating conditions used for measuring the reverse osmosis membrane performance in this invention are as follows: feed solution 2000 mg·L⁻¹ -1 The solution is an aqueous sodium chloride solution with a pH of 7.0 ± 0.5, an operating pressure of 225 psi (1.55 MPa), and an operating temperature of 25 ± 1 °C.

[0130] 2. Dynamic anti-pollution performance evaluation

[0131] The permeation flux decay rate (FDR) is defined as the rate of decay of the membrane's test permeation flux (F2) compared to the initial permeation flux (F1) after a period of operation following the addition of contaminants to the test system. It is 1-F2 / F1.

[0132] Flux recovery rate (FRR) is defined as the ratio of the tested flux (F3) of the membrane after fouling and alkaline cleaning to the initial flux (F1) before fouling, which is F3 / F1.

[0133] The dynamic antifouling test conditions for the reverse osmosis membrane in this invention are as follows:

[0134] F1 refers to the process of applying pressure of 1.55 MPa to a membrane at 25°C, pH 7.0 ± 0.5, and sodium chloride concentration of 2000 mg·L⁻¹. -1 Flux of aqueous solution after cross-flow filtration for 1 hour;

[0135] F2 is the flux obtained after adding 100 ppm of the pollutant polyoxyethylene 20 oil ether to the above sodium chloride aqueous solution and continuing to run for 2 hours after measuring F1.

[0136] F3 was performed after measuring F1 and F2 above. The membrane was washed with a NaOH solution at pH 12.0 ± 0.5 for 12 hours, and then subjected to a test at 1.55 MPa pressure at 25 ± 1 °C, pH 7.0 ± 0.5, and a sodium chloride concentration of 2000 mg / L. -1 Flux of aqueous solution after cross-flow filtration for 1 hour.

[0137] 3. Membrane water contact angle test

[0138] The water contact angle was measured using a Krüss DSA (water contact angle meter). The reverse osmosis membranes were dried in a vacuum oven at 80°C for one day. The test method involved dropping 1–4 μL of deionized water onto the membrane surface and calculating the water contact angle 10 seconds after the pure water droplet landed. Five measurements were taken at appropriate test locations, and the average value was calculated.

[0139] 4. Molecular weight test of N-hydroxyethylacrylamide-co-epoxy polymer

[0140] The analysis was performed using permeation gel chromatography (Shimadzu CTO-20A). A Shim-pack GPC-80M column and a Shim-pack GPC 800p guard column were used. The mobile phase consisted of an aqueous solution of 0.2 M NaNO3 and 0.01 M NaH2PO4 (pH = 9.0). The flow rate was set to 0.5 mL / min, the column temperature to 30 °C, and the injection volume to 50 μL. A differential refractive index detector (RID-10A) was used. Four polyethylene glycols with different molecular weights (PEG 5000, PEG 10000, PEG 35000, and PEG 100000) were selected as standards. A standard curve was plotted, and the molecular weight of the N-hydroxyethylacrylamide-co-epoxy polymer was determined.

[0141] 5. Diaphragm scratch resistance test

[0142] This test primarily simulates the effects of compression and scratching between the front side of the reverse osmosis membrane and the feed water separator during the membrane element rolling process. The prepared reverse osmosis membrane is cut into 12cm × 15cm rectangles for later use. A 20cm × 20cm feed water separator is placed on the test platform, and then the prepared rectangular reverse osmosis membrane is placed on the feed water separator with the membrane front side facing the separator. A 2kg cube metal block (12cm × 12cm × 12cm) is then placed on the reverse osmosis membrane. Figure 1 As shown. One end of the metal rope is fixed to the metal block, and the other end is connected to a tensile testing machine (Guangdong Zhongye Precision Technology HTS-LLY2500R). Tension is applied towards the tensile testing machine at a speed of 10 cm / min. -1 The stretching distance was 15cm, and the measurement temperature was 25±1℃. Each membrane was tested for scratch resistance three times, and then the desalination rate after the membrane was scratched was tested.

[0143] Example 1

[0144] The preparation process of antifouling polyamide reverse osmosis membrane is as follows:

[0145] Step 1: Prepare a polysulfone porous support layer on the surface of polyethylene terephthalate nonwoven fabric. Specifically, prepare a polysulfone casting solution containing 16.5 wt% polysulfone resin in N,N-dimethylformamide; then apply the filtered and degassed polysulfone casting solution onto the polyethylene terephthalate nonwoven fabric; immediately immerse it in deionized water in a coagulation bath to form a membrane through phase inversion, and then wash it with water to obtain a polysulfone porous support layer with a pore size of 45 nm and a thickness of 50 μm, and then cut it into a 16 cm × 12 cm membrane sheet.

[0146] Step 2: Dissolve m-phenylenediamine, camphor sulfonic acid, and triethylamine in deionized water, stir and mix evenly to prepare an aqueous solution containing 2.5 wt% m-phenylenediamine, 3.2 wt% camphor sulfonic acid, and 1.6 wt% triethylamine. Camphor sulfonic acid and triethylamine form a buffer, p-triethylamine camphor sulfonate. The pH of the aqueous solution is about 11.5.

[0147] Step 3: Dissolve pyromellitic chloride in isopar G isoalkane, stir and mix evenly to prepare an organic phase solution containing 0.12 wt% pyromellitic chloride;

[0148] Step 4: Attach the polysulfone porous support layer membrane prepared in Step 1, surface-up, to the plate frame. Immerse it in the aqueous solution prepared in Step 2 at 25°C for 60 seconds. Then remove the plate frame and place it on a paper towel on top of the plastic plate. Gently squeeze with a pressure roller to remove excess aqueous solution remaining on the surface. Then, contact it with the organic solution containing trimesoyl chloride from Step 3 and perform an interfacial polymerization reaction at 25°C for 30 seconds. Discard the excess organic solution. Then, use an air knife to evenly blow away the solvent until there is no residual solvent on the membrane surface. Finally, place it in an 80°C oven for heat treatment for 5 minutes. After removing it from the oven, rinse the membrane surface with pure water until it becomes hydrophilic.

[0149] Step 5: Place the membrane obtained in Step 4 into a 6 wt% glycerol aqueous solution at 60°C for 30 seconds. Then, use an air knife to evenly blow the membrane until there is no residual glycerol solution on the membrane surface and back. Finally, coat the membrane surface with a mixed aqueous solution of 1.0 wt% N-hydroxyethylacrylamide-co-epoxy polymer 1, 0.25 wt% glutaraldehyde, 0.05 wt% 2,4,6-tris(dimethylaminomethyl)phenol and 0.1 wt% polyacrylic acid. Use a pressure roller to roll off the excess mixed solution, and then place it in an 80°C oven for heat treatment for 5 minutes to obtain the high-efficiency antifouling polyamide reverse osmosis membrane of Example 1.

[0150] Synthesis method of N-hydroxyethylacrylamide-co-epoxy polymer 1: N-hydroxyethylacrylamide monomer and active allyl epoxy polyether KL-11 monomer were synthesized by free radical at a mass ratio of 90:10, with a solid content of 30% by mass. The chemical crosslinking agent was N,N'-methylenebisacrylamide, and the amount used was 0.1wt% of the total mass of monomers (the total mass of N-hydroxyethylacrylamide monomer and epoxy-containing monomers, the same below). The solvent was water, the reaction temperature was 50℃, the initiator was azobisisobutyrazoline hydrochloride, and the amount used was 0.5wt% of the total mass of monomers. The reaction time was 4 hours, and the pH was controlled at 5.0 to obtain N-hydroxyethylacrylamide-co-epoxy polymer 1. The final polymer weight average molecular weight was 68,000.

[0151] Example 2

[0152] The difference from Example 1 is that in step five, N-hydroxyethylacrylamide-co-epoxy polymer 1 is replaced with N-hydroxyethylacrylamide-co-epoxy polymer 2. The difference between it and N-hydroxyethylacrylamide-co-epoxy polymer 1 is that the epoxy monomer is replaced with allyl glycidyl ether. At the same time, N-hydroxyethylacrylamide monomer and allyl glycidyl ether are subjected to free radical polymerization at a mass ratio of 85:15, the reaction temperature is 60°C, the reaction time is 6 hours, and other operations and conditions remain unchanged. The weight average molecular weight of N-hydroxyethylacrylamide-co-epoxy polymer 2 is 45,000, thus obtaining the high-efficiency antifouling polyamide reverse osmosis membrane of Example 2.

[0153] Example 3

[0154] The difference from Example 1 is that in step five, N-hydroxyethylacrylamide-co-epoxy polymer 1 is replaced with N-hydroxyethylacrylamide-co-epoxy polymer 3. The difference between N-hydroxyethylacrylamide-co-epoxy polymer 3 and N-hydroxyethylacrylamide-co-epoxy polymer 1 is that the initiator is replaced with azobisisobutyramidine hydrochloride. At the same time, the amount of initiator added is adjusted to 1% of the total mass of monomers, the amount of chemical crosslinking agent added is adjusted to 0.2%, the reaction temperature is 70°C, and other operations and conditions remain unchanged. The weight average molecular weight of N-hydroxyethylacrylamide-co-epoxy polymer 3 is 59,000, and the high-efficiency antifouling polyamide reverse osmosis membrane of Example 3 is obtained.

[0155] Example 4

[0156] The difference from Example 1 is that in step five, a mixed aqueous solution of 1.2 wt% N-hydroxyethylacrylamide-co-epoxy polymer 4, 0.5 wt% trimesin, 0.1 wt% 2,4,6-tris(dimethylaminomethyl)phenol, and 0.1 wt% polyacrylic acid is used. The difference between N-hydroxyethylacrylamide-co-epoxy polymer 4 and N-hydroxyethylacrylamide-co-epoxy polymer 1 is that N-hydroxyethylacrylamide monomer and active allyl epoxy polyether KL-11 monomer are subjected to free radical polymerization at a mass ratio of 80:20. All other operations and conditions remain unchanged. The weight-average molecular weight of N-hydroxyethylacrylamide-co-epoxy polymer 4 is 62,000. In step five, the oven heat treatment temperature is 60°C, and the heat treatment time is 8 minutes. All other operations and conditions remain unchanged, resulting in the high-efficiency antifouling polyamide reverse osmosis membrane of Example 4.

[0157] Example 5

[0158] The difference from Example 1 is that in step five, a mixed aqueous solution of 0.8 wt% N-hydroxyethylacrylamide-co-epoxy polymer 1, 0.4 wt% glutaraldehyde and 0.05 wt% 2,4,6-tris(dimethylaminomethyl)phenol is used. The heat treatment temperature in step five is 70°C and the heat treatment time is 6 minutes. All other operations and conditions remain unchanged, resulting in the high-efficiency antifouling polyamide reverse osmosis membrane of Example 5.

[0159] Example 6

[0160] The difference from Example 1 is that in step five, a mixed aqueous solution of 1.0 wt% N-hydroxyethylacrylamide-co-epoxy polymer 2, 0.25 wt% glutaraldehyde and 0.1 wt% polyacrylic acid is used. The amount of chemical crosslinking agent is 0.3% of the total mass of monomers, and the amount of initiator is 2% of the total mass of monomers. All other operations and conditions remain unchanged, and the high-efficiency antifouling polyamide reverse osmosis membrane of Example 6 is obtained.

[0161] Comparative Example 1

[0162] The difference from Example 1 is that step five, coating the mixed aqueous solution, is omitted, while other operations and conditions remain unchanged, resulting in the reverse osmosis membrane of Comparative Example 1.

[0163] Comparative Example 2

[0164] The difference from Example 1 is that 2,4,6-tris(dimethylaminomethyl)phenol and polyacrylic acid are not added in step five, while other operations and conditions remain unchanged, resulting in the reverse osmosis membrane of Comparative Example 2.

[0165] Comparative Example 3

[0166] The difference from Example 1 is that glutaraldehyde, 2,4,6-tris(dimethylaminomethyl)phenol and polyacrylic acid are not added in step five, while other operations and conditions remain unchanged, resulting in the reverse osmosis membrane of Comparative Example 3.

[0167] Comparative Example 4

[0168] The difference from Example 1 is that in step five, the mixed aqueous solution of 1.0 wt% N-hydroxyethylacrylamide-co-epoxy polymer 1, 0.25 wt% glutaraldehyde, 0.05 wt% 2,4,6-tris(dimethylaminomethyl)phenol and 0.1 wt% polyacrylic acid was replaced with an aqueous solution of 1.0 wt% polyvinyl alcohol 1799. All other operations and conditions remained unchanged, and the reverse osmosis membrane of Comparative Example 4 was obtained.

[0169] The performance indicators and test data of the reverse osmosis membranes prepared in the embodiments and comparative examples of the present invention are listed in Table 2.

[0170] Table 2. Performance data of the antifouling layer of the reverse osmosis membrane.

[0171]

[0172] The above embodiments are merely illustrative examples and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A high-efficiency anti-fouling polyamide reverse osmosis membrane, characterized in that, The polyamide reverse osmosis membrane includes a base layer, a porous support layer, a polyamide separation layer, and a cross-linked polymer antifouling layer; wherein the cross-linked polymer antifouling layer is an N-hydroxyethylacrylamide-co-epoxy polymer / aldehyde cross-linked polymer.

2. The high-efficiency anti-fouling polyamide reverse osmosis membrane according to claim 1, characterized in that, The cross-linked polymer antifouling layer is obtained by coating a mixed solution of N-hydroxyethylacrylamide-co-epoxy polymer, aldehyde and catalyst onto the surface of a polyamide separation layer and then heat-treating it.

3. The high-efficiency anti-fouling polyamide reverse osmosis membrane according to claim 2, characterized in that, The N-hydroxyethylacrylamide-co-epoxy polymer was synthesized by free radical copolymerization, and the monomers included N-hydroxyethylacrylamide and epoxy-containing monomers.

4. The high-efficiency anti-fouling polyamide reverse osmosis membrane according to claim 3, characterized in that, N-hydroxyethylacrylamide-co-epoxy polymers satisfy at least one of the following conditions: (1) The weight-average molecular weight of the N-hydroxyethylacrylamide-co-epoxy polymer is in the range of 20,000 to 150,000 Da, preferably 30,000 to 80,000 Da; (2) The epoxy-containing monomers include one or more of glycidyl methacrylate, glycidyl methacrylate, 2-propionic-2-methyl-2-[2-(2-oxybenzoxy)ethoxy]ethyl 2-propionic acid, allyl glycidyl ether, and active allyl epoxy polyether; (3) The mass ratio of the N-hydroxyethyl acrylamide to the epoxy-containing monomer is 95:5 to 75:25; (4) The free radical copolymerization reaction further includes a chemical crosslinking agent, which includes one or more of trimethylolpropane trimethacrylate, ethylene glycol dimethacrylate, trimethylolpropane diallyl ether, triallyl isocyanate, and N,N'-methylenebisacrylamide; preferably, the amount of the chemical crosslinking agent is 0.01 to 1.0 wt% of the total mass of N-hydroxyethylacrylamide and epoxy-containing monomers, preferably 0.05 to 0.3 wt%; (5) The free radical copolymerization reaction further includes an initiator, which includes one or more of the following: azobisisobutyramidine hydrochloride, azobisisobutyramidine imidazoline hydrochloride, azobisisobutyramidine imidazoline sulfate, azobiscyanopentanoic acid, azobis(hydroxyethyl)imidazoline propane hydrochloride, azobisisobutyramidine, azobis(1-imino-1-pyrrolidinyl-2-ethylpropyl) hydrochloride, azobis(N-2-carboxyethyl-2-methylpropanediamine) hydrate, azobis[2-methyl-N-(1,1-dihydroxymethyl-2-hydroxyethyl)propionamide], and azobis[2-methyl-N-(2-hydroxyethyl)propionamide]. Preferably, the amount of the initiator is 0.01 to 5.0 wt% of the total mass of N-hydroxyethylacrylamide and epoxy-containing monomers, and more preferably 0.5 to 2.0 wt%. (6) The free radical copolymerization reaction is carried out in a solvent environment, and the solvent includes one or more of water, methanol, ethanol, isopropanol, N-methylpyrrolidone, N,N-dimethylformamide, dimethylacetamide, and dimethyl sulfoxide; (7) The reaction temperature of the free radical copolymerization reaction is 20-80℃, preferably 40-70℃, and the reaction time is 0.5-24 hours, preferably 4-8 hours.

5. The high-efficiency anti-fouling polyamide reverse osmosis membrane according to claim 2, characterized in that, The N-hydroxyethylacrylamide-co-epoxy polymer / aldehyde crosslinking polymer satisfies at least one of the following conditions: (1) The aldehydes include one or more of the following: glyoxal, glutaraldehyde, adipaldehyde, isophthalaldehyde, 5-hydroxyisophthalaldehyde, 2,5-dihydroxyisophthalaldehyde, 2,4-dihydroxyisophthalaldehyde, 2,4-dicarboxymethylpyrogallol, terephthalaldehyde, 2,6-dihydroxy-1,4-phenylenedialdehyde, pyromellitic pyromellitic aldehyde, 2-hydroxy-1,3,5-phenylenedialdehyde, 2,4-dihydroxy-1,3,5-pyromellitic pyromellitic aldehyde, and 2,4,6-tricarboxymethylpyromellitic pyromellitic aldehyde; (2) The catalyst includes one or more of hydrochloric acid, sulfuric acid, phosphoric acid, 2,4,6-tris(dimethylaminomethyl)phenol, phenol, resorcinol, pyrogallol, acetic acid, and polyacrylic acid; (3) The solvent of the mixed solution is water; (4) In the mixed solution, the concentration of N-hydroxyethylacrylamide-co-epoxy polymer is 0.01-5 wt%, preferably 0.1-1 wt%; (5) In the mixed solution, the concentration of aldehyde is 0.01 to 1 wt%, preferably 0.05 to 0.5 wt%; (6) In the mixed solution, the concentration of the catalyst is 0.005 to 0.5 wt%, preferably 0.01 to 0.1 wt%; (7) The heat treatment temperature is 40 to 100°C, preferably 60 to 80°C; the time is 1 to 10 minutes, preferably 3 to 5 minutes.

6. A method for preparing a high-efficiency antifouling polyamide reverse osmosis membrane according to any one of claims 1-5, characterized in that, Includes the following steps: S1: Obtain a porous support layer on the substrate surface; S2: The porous support layer is immersed in an aqueous solution containing polyamine to remove the residual aqueous solution on the surface. Then it is contacted with an organic solution containing polyacrylamide chloride to carry out an interfacial polymerization reaction to remove the residual organic solution on the surface. After heat treatment, it is washed with water. The membrane is then immersed in a glycerol solution to remove excess glycerol solution and form a moisturizing polyamide separation layer. S3: After moisturizing, the surface of the polyamide separation layer is coated with a mixed solution of N-hydroxyethylacrylamide-co-epoxy polymer, aldehyde and catalyst. The excess mixed solution is removed, and heat treatment is performed to obtain a high-efficiency anti-fouling polyamide reverse osmosis membrane.

7. Use of a high-efficiency antifouling polyamide reverse osmosis membrane, wherein the reverse osmosis membrane is the reverse osmosis membrane according to claims 1-5, and the reverse osmosis membrane is used in a water treatment assembly or water treatment method.

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