An anti-microbial contaminated reverse osmosis membrane and a production process thereof

Abstract

The application relates to the field of water treatment and membrane separation technology, and particularly discloses an anti-microbial contamination reverse osmosis membrane and a production process thereof. The production process of the anti-microbial contamination reverse osmosis membrane comprises the following steps: taking a base film, immersing the base film in a water-phase solution containing a polyamine monomer for treatment, immersing the base film in an oil-phase solution containing trimesoyl chloride for treatment, then immersing the obtained film piece after activation treatment in a mixed aqueous solution containing citric acid and ferrous sulfate, then immersing the film piece in an aqueous solution containing an anti-microbial functional monomer without cleaning, adding hydrogen peroxide, making the concentration of the hydrogen peroxide 50-200 mg / L, treating the film piece at 50-60 DEG C for 50-80 min under nitrogen protection, obtaining a functionalized film piece, and finally immersing the functionalized film piece in an aqueous solution containing vitamin C, rinsing with deionized water, immersing the functionalized film piece in a glycerol aqueous solution, and drying to obtain the anti-microbial contamination reverse osmosis membrane. The application can realize firm combination of a functional layer and a polyamide separation layer on the reverse osmosis membrane, avoid peeling of the coating, and ensure long-term anti-microbial stability.

Description

Technical Field

[0001] This application relates to the field of water treatment and membrane separation technology, and more specifically, it relates to an antimicrobial fouling reverse osmosis membrane and its manufacturing process. Background Technology

[0002] Reverse osmosis membrane technology, with its high efficiency in desalination, removal of trace organic matter and pathogens, has become a core process in fields such as seawater desalination, municipal wastewater treatment and reuse, industrial pure water production, and household drinking water purification. Among them, thin-film composite (TFC) reverse osmosis membranes dominate the global reverse osmosis membrane market due to their excellent separation performance and mechanical strength. A typical TFC membrane usually consists of a polysulfone porous support layer and a polyamide ultrathin separation layer formed by interfacial polymerization.

[0003] However, in practical engineering applications, reverse osmosis membranes face a severe and widespread problem—membrane fouling. Membrane fouling is mainly classified into three categories: inorganic scaling, organic fouling, and microbial fouling. Among them, microbial fouling (biofouling) is considered the most difficult to control and the most harmful type of fouling. Its formation process is roughly as follows: microorganisms in the water (such as bacteria, fungi, and algae) first reversibly adsorb onto the membrane surface, and then secrete extracellular polymeric substances (EPS), forming a viscous biofilm. Once formed, the biofilm rapidly proliferates and captures more microorganisms and organic matter, leading to a series of serious consequences: a sharp decline in flux, deterioration of membrane separation performance, and shortened membrane element lifespan.

[0004] To address the problem of biofouling, researchers both domestically and internationally have conducted extensive research and developed various antimicrobial contamination modification technologies, mainly including (1) physical blending, which involves incorporating antibacterial agents (such as nano-silver, zinc oxide, etc.) into the casting solution during membrane fabrication; (2) surface coating, which involves coating the surface of the finished membrane with a layer of hydrophilic polymer containing antibacterial agents; and (3) surface grafting, which uses chemical bonds to graft antibacterial functional groups (such as quaternary ammonium salts, zwitterionic polymers, etc.) onto the membrane surface. Among these, the surface coating method is favored due to its intuitive operation, low equipment investment, and good compatibility with existing production lines. However, the coating layer and the membrane surface are mainly bound by weak interactions such as hydrogen bonds, electrostatic adsorption, or van der Waals forces, resulting in weak bonding. Under the shear force of cross-flow filtration, the coating is prone to peeling or dissolving, leading to a lack of long-lasting antibacterial effect and making it difficult to meet the requirements for long-term stable operation of reverse osmosis membranes. Therefore, it is currently urgent to propose a solution to address the above-mentioned technical problems. Summary of the Invention

[0005] In order to achieve a strong bond between the functional layer and the polyamide separation layer on the reverse osmosis membrane, prevent coating peeling, and ensure long-term antimicrobial stability, this application provides an antimicrobial fouling reverse osmosis membrane and its manufacturing process.

[0006] In a first aspect, this application provides a manufacturing process for an antimicrobial fouling reverse osmosis membrane, employing the following technical solution: A manufacturing process for an antimicrobial fouling reverse osmosis membrane includes the following steps: (1) Immerse the base film in an aqueous solution containing polyamine monomers for treatment, and remove it to remove any residual liquid from the surface; (2) Immerse the base film obtained in step (1) in an oil phase solution containing pyromellitic chloride, and remove it to remove the residual liquid on the surface; (3) Dry the base film obtained in step (2) at 40-55℃ for 3-5 min, and then immerse it in a mixed aqueous solution containing citric acid and ferrous sulfate at 45-60℃ for 15-20 min to obtain the activated film. (4) The activated membrane obtained in step (3) is directly immersed in an aqueous solution containing antimicrobial functional monomers without being washed, and hydrogen peroxide is added to make the hydrogen peroxide concentration 50-200 mg / L. Under nitrogen protection, it is treated at 50-60℃ for 50-80 min to obtain a functionalized membrane. (5) The functionalized membrane obtained in step (4) is first soaked in an aqueous solution containing vitamin C, then rinsed with deionized water, then immersed in an aqueous solution of glycerol for treatment, and finally dried to obtain an antimicrobial fouling reverse osmosis membrane. In step (4) above, the antimicrobial functional monomer is composed of carboxybetaine methacrylate, [2-(methacryloyloxy)ethyl]trimethylammonium chloride, methacrylated chitosan and 3-allyl-5,5-dimethylhydantoin in a weight ratio of (6-8):(2.5-3.5):(1-1.5):1.

[0007] By adopting the above technical solution, steps (1) and (2) achieve aqueous phase treatment of the base membrane followed by alternating oil phase interfacial polymerization, generating a dense polyamide (PA) ultrathin separation layer in situ, thus forming a classic TFC reverse osmosis membrane structure. In step (3), citric acid (CA), as a tricarboxylic acid, reacts with Fe in ferrous sulfate. 2+ A stable citric acid-ferrous complex is formed, and through hydrogen bonding and coordination between the carboxyl group of CA and the carboxyl / amide group on the PA surface, Fe... 2+The material is loaded onto the PA surface and subjected to a weak Fenton reaction under heating at 40-60℃, resulting in the controlled generation of hydroxyl radicals on the PA surface. This slightly oxidizes the PA surface and generates free radical active sites, providing "anchoring points" for subsequent antimicrobial functional monomers. In step (4), without rinsing, a high concentration of CA-e remains on the membrane surface. 2+ The complex and surface-active free radical environment prevent the active sites from being quenched by water or oxygen, maintaining continuous initiation ability; while the addition of hydrogen peroxide and Fe loaded on the membrane surface... 2+ A surface-confined Fenton system is constructed, which continuously and controllably generates hydroxyl radicals on the PA surface, significantly improving the initiation efficiency. Then, treatment at 50-60℃ for 50-80 min provides suitable thermal driving force, causing the antimicrobial functional monomers to undergo surface-initiated free radical copolymerization on the PA surface, forming a cross-linked network functional layer. In step (5), the strong reducing properties of VC are used to quench the free radicals remaining on the membrane surface, terminate the graft polymerization reaction, and glycerol is subsequently used to prevent the membrane from drying and shrinking, finally obtaining an antimicrobial fouling reverse osmosis membrane.

[0008] The combination of antimicrobial functional monomers includes: the zwitterionic structure of carboxybetaine methacrylate, which forms a strongly bound water layer through electrostatic hydration to resist initial protein / bacterial adhesion; [2-(methacryloyloxy)ethyl]trimethylammonium chloride, which can destroy microbial cell membranes, achieving contact sterilization and compensating for the lack of passive antifouling properties of betaine; methacrylylated chitosan, which provides long-lasting antibacterial and film-forming toughness with glucosamine units, and whose multi-hydroxyl structure enhances hydrophilicity and coating mechanical strength, reducing shearing peeling; and 3-allyl-5,5-dimethylhydantoin, which imparts chlorine-resistant cleaning and antibacterial regeneration capabilities. Thus, the combination of these four monomers achieves synergistic antimicrobial protection for long-lasting effects. Furthermore, the aforementioned antimicrobial functional monomers form functional polymer chains that "grow" from the PA surface, forming a chemically bonded interpenetrating / grafted structure with the substrate, rather than a physical superposition of later coatings. This greatly enhances the interfacial bonding strength, making it less prone to cracking, curling, or peeling under the high-velocity cross-flow shearing of reverse osmosis operation, and cleverly combines surface activation (CA-Fe). 2+ The combination of surface-limited Fenton initiation (adding H2O2) and in-situ covalent graft copolymerization (quaternary monomers) transforms the traditional "easily peelable physical coating layer" into a "functional layer that grows integrally with the polyamide separation layer." Without sacrificing the separation performance of the TFC membrane, a strong bond is achieved between the functional layer and the polyamide separation layer on the reverse osmosis membrane, preventing coating peeling and ensuring long-term antimicrobial stability.

[0009] Preferably, the antimicrobial functional monomer is composed of carboxybetaine methacrylate, [2-(methacryloyloxy)ethyl]trimethylammonium chloride, methacrylated chitosan, and 3-allyl-5,5-dimethylhydantoin in a weight ratio of 55:25:12:8.

[0010] By adopting the above technical solution, the whole is in CA-Fe 2+ Under the surface initiation of H2O2, a uniform interpenetrating network is easily formed, which has good polymerization compatibility and structural stability. It can achieve mutual restraint and excellent functional complementarity, jointly supporting the goal of firm bonding and long-term stable operation of the antimicrobial functional layer and the PA separation layer.

[0011] Preferably, in step (3), the ferrous ion concentration in the mixed aqueous solution containing citric acid and ferrous sulfate is 0.001%-0.01% (w / v).

[0012] By adopting the above technical solution, the maximum covalent grafting can be achieved with minimal surface activation, while maximizing the protection of the intrinsic properties of the polyamide separation layer. The "activation-grafting" process is controllable and stable, thereby ensuring that the antimicrobial functional monomers achieve an appropriate grafting density and crosslinking degree on the PA surface. This ensures that the antifouling / bactericidal groups are fully exposed, while avoiding surface embrittlement or excessive flux reduction due to excessive grafting, thus achieving excellent synergy between separation performance and antifouling performance.

[0013] Preferably, in step (4), the concentration of the antimicrobial functional monomer in the aqueous solution containing the antimicrobial functional monomer is 0.8%-1.0% (w / v).

[0014] By adopting the above technical solution, at this concentration, a continuous, uniform, appropriately thick, and synergistic antimicrobial functional layer can be constructed in a mild and controllable surface grafting (grafting) manner. This provides sufficient bactericidal sites without excessively increasing mass transfer resistance, maintaining the original water permeability and desalination rate of the reverse osmosis membrane, achieving a balance between separation performance and antimicrobial performance, and thus ensuring excellent performance of strong bonding, long-lasting antibacterial effect, and high-flux desalination.

[0015] Preferably, step (5) is specifically set as follows: the functionalized membrane obtained in step (4) is first soaked in an aqueous solution containing vitamin C, then rinsed with deionized water, then immersed in an ethanol / water mixed solution containing 3-(4-vinylbenzyl)-5,5-dimethylhydantoin and glutaraldehyde, soaked at 35-40°C for 50-60 minutes, then rinsed with deionized water, then immersed in an aqueous glycerol solution for treatment, and finally dried to obtain an antimicrobial fouling reverse osmosis membrane; In an ethanol / water mixed solution containing 3-(4-vinylbenzyl)-5,5-dimethylhydantoin and glutaraldehyde, the concentration of 3-(4-vinylbenzyl)-5,5-dimethylhydantoin is 1.8%-2.4% (w / v), and the concentration of glutaraldehyde is 0.4%-0.6% (w / v).

[0016] By employing the above technical solution, glutaraldehyde, as a bifunctional crosslinking agent, can construct additional covalent crosslinking bridges between the grafted polymer chains, significantly improving the mechanical strength, wear resistance, and anti-swelling ability of the functional layer, making it less prone to microcracks or overall peeling under high-pressure cross-flow shearing of reverse osmosis; 3-(4-vinylbenzyl)-5,5-dimethylhydantoin can penetrate into the network voids of the functional layer through hydrogen bonds and van der Waals forces, forming a more rigid aromatic ring-aldehyde crosslinking network with glutaraldehyde, filling network defects, making the surface of the functional layer more dense and uniform, reducing local erosion caused by structural looseness, significantly improving the impact resistance under high-pressure cross-flow, and can slowly release... The active chlorine is used to kill microorganisms and can be regenerated in chlorine-containing solutions after consumption, achieving "long-lasting and regenerable antibacterial properties". The combination of 3-(4-vinylbenzyl)-5,5-dimethylhydantoin and glutaraldehyde enables post-treatment structural densification and functional enhancement based on free radical grafting. The two work synergistically to upgrade the functional layer from a single grafted polymer to a covalently cross-linked, structurally dense, and regenerable antibacterial composite protective barrier. This provides multi-dimensional enhancements to the functional layer's firm bonding, prevention of shedding, and long-lasting antibacterial effect, further systematically supporting the long-term stability of the reverse osmosis membrane against microbial fouling, resulting in a higher-quality antimicrobial fouling reverse osmosis membrane. Simultaneously, a 3-(4-vinylbenzyl)-5,5-dimethylhydantoin concentration of 1.8%-2.4% (w / v) and a glutaraldehyde concentration of 0.4%-0.6% (w / v) facilitates process compatibility and structural balance, leading to better enhancement effects.

[0017] Preferably, in the ethanol / water mixed solution containing 3-(4-vinylbenzyl)-5,5-dimethylhydantoin and glutaraldehyde, the concentration of 3-(4-vinylbenzyl)-5,5-dimethylhydantoin is 2% (w / v) and the concentration of glutaraldehyde is 0.55% (w / v).

[0018] By adopting the above technical solution, the maximum interfacial bonding strength and long-lasting halogen amine antibacterial reserve can be obtained with the minimum cross-linking strength, while maintaining the precise parameter combination of water flux and desalination rate. This upgrades the functional layer from a "simple grafting layer" to a composite protective barrier of "cross-linking and locking + antibacterial regenerability", with better overall performance.

[0019] Preferably, in step (1), a low molecular weight branched polyethyleneimine is added to the aqueous solution containing the polyamine monomer. The amount of low molecular weight branched polyethyleneimine added is 5%-10% of the mass of the polyamine monomer, and the Mw of the low molecular weight branched polyethyleneimine is 600-1800 Da.

[0020] By employing the above technical solution, low molecular weight branched polyethyleneimine (PEI) is covalently embedded into the forming polyamide network. PEI molecular segments are uniformly distributed on the surface and shallow layer of the polyamide separation layer, and these PEI segments still retain a large number of unreacted free amine groups. Subsequently, glutaraldehyde is used to establish multiple covalent bonds between the amine groups of PEI and the active groups of 3-(4-vinylbenzyl)-5,5-dimethylhydantoin, further strengthening the interfacial bonding between the functional layer and the PA separation layer, ultimately improving the long-term stability of the resulting antimicrobial fouling reverse osmosis membrane. Simultaneously, the Mw of the low molecular weight branched polyethyleneimine, ranging from 600 to 1800 Da, is carefully selected, achieving an optimal balance between "providing sufficient anchor points" and "not damaging the polyamide structure."

[0021] Preferably, in step (1), the polyamine monomer is m-phenylenediamine, and its concentration in the aqueous solution is 2-5 wt%.

[0022] By adopting the above technical solution, selecting m-phenylenediamine (MPD) at a concentration of 2-5 wt% represents the optimal process window based on the compatibility of classic TFC reverse osmosis membrane preparation and subsequent antimicrobial modification: it ensures that the polyamide separation layer itself possesses high desalination, moderate flux, good mechanical strength, and abundant surface active sites, while also providing a suitable environment for the copolymerization and regulation of low molecular weight branched PEI and CAFe. 2+ Anchoring activation, surface grafting, and post-GAADMH crosslinking provide a structurally stable and chemically compatible substrate, which is a prerequisite for the entire process to achieve "firm bonding, no shedding, and long-lasting antibacterial effect".

[0023] Preferably, in step (2), the concentration of pyromellitic chloride in the oil phase solution is 0.05-0.3 wt%.

[0024] By adopting the above technical solution, the concentration of trimesoyl chloride (TMC) of 0.05-0.3wt% is selected as a key parameter that works synergistically with the entire process of aqueous phase, PEI addition, and subsequent activation-grafting-post-treatment. It ensures that the polyamide separation layer has high desalination, moderate throughput, good mechanical strength, and suitable surface functional groups and morphology, providing a structurally stable and chemically compatible substrate for the firm bonding, anti-detachment, and long-term stability of the antimicrobial functional layer.

[0025] Secondly, this application provides an antimicrobial fouling reverse osmosis membrane, characterized in that it is manufactured using the above-mentioned antimicrobial fouling reverse osmosis membrane production process.

[0026] In summary, this application has the following beneficial effects: 1. This application ingeniously combines surface activation (CA-Fe) 2+ The process of surface-limited Fenton initiation (adding H2O2) and in-situ covalent graft copolymerization (four special combination monomers) transforms the traditional "easily peelable physical coating layer" into a "functional layer that grows integrally with the polyamide separation layer". This achieves a strong bond between the functional layer and the polyamide separation layer on the reverse osmosis membrane and exhibits excellent long-term antimicrobial stability, resulting in a high-quality antimicrobial fouling reverse osmosis membrane. 2. This application uses 3-(4-vinylbenzyl)-5,5-dimethylhydantoin and glutaraldehyde in combination, enabling post-treatment of structural densification and functional enhancement based on free radical grafting. The two work synergistically to upgrade the functional layer from a single grafted polymer to a covalently cross-linked, structurally dense, antibacterial, and regenerable composite protective barrier, further systematically supporting the long-term stability of the reverse osmosis membrane against microbial fouling. At the same time, based on this, the use of low molecular weight branched polyethyleneimine to covalently embed into the forming polyamide network, combined with glutaraldehyde and 3-(4-vinylbenzyl)-5,5-dimethylhydantoin, further strengthens the interfacial bonding between the functional layer and the PA separation layer, thereby further improving the long-term stability of the resulting antimicrobial fouling reverse osmosis membrane. Detailed Implementation

[0027] The present application will be further described in detail below with reference to embodiments and comparative examples.

[0028] Unless otherwise specified, all raw materials used in the preparation examples, embodiments and comparative examples of this application are commercially available.

[0029] P-3500LCD MB7 polysulfone, polyethylene glycol with an average molecular weight of 6000, and N,N-dimethylformamide were mixed in a mass ratio of 14g:2.5g:83g. The mixture was heated and stirred at 85°C for 7 hours, then allowed to stand at room temperature for 12 hours to remove bubbles. The degassed mixture was then poured into the solution tank of a film-coating machine, and nonwoven fabric (100g / m²) was installed. 2 The mixture (with a thickness of 120 μm) was uniformly coated onto the nonwoven fabric using a scraper, then added to cold water at 15°C for 60 seconds to solidify, then immersed in room temperature water at 25°C for 60 seconds to displace it, and finally washed in hot water at 65°C for 120 seconds to obtain a base film with a polysulfone support layer thickness of 100 μm.

[0030] Example Example 1

[0031] A manufacturing process for an antimicrobial fouling reverse osmosis membrane includes the following steps: (1) Immerse the base film in an aqueous solution containing polyamine monomers for 120s, then remove it and remove any residual liquid from the surface; (2) Immerse the base film obtained in step (1) in an oil phase solution containing trimesoyl chloride for 40 seconds, and remove it to remove the residual liquid on the surface; (3) The base film obtained in step (2) is dried at 47.5°C for 4 min and then immersed in a mixed aqueous solution containing citric acid and ferrous sulfate at 52.5°C for 17.5 min to obtain the activated film. (4) The activated membrane obtained in step (3) was directly immersed in an aqueous solution containing antimicrobial functional monomers without being washed, and hydrogen peroxide was added to make the hydrogen peroxide concentration 125 mg / L. Under nitrogen protection, it was treated at 55°C for 65 min to obtain the functionalized membrane. (5) The functionalized membrane obtained in step (4) is first soaked in an aqueous solution containing 0.2% (w / v) vitamin C for 5 minutes, then rinsed with deionized water, then soaked in an aqueous solution of 20% glycerol for 5 minutes, and finally dried to obtain an antimicrobial fouling reverse osmosis membrane. Note: In the above operation, the aqueous phase solution consists of a polyamine monomer, sodium dodecyl sulfate, and pure water; wherein the polyamine monomer is m-phenylenediamine, with a concentration of 3.5 wt% in the aqueous phase solution, and the concentration of sodium dodecyl sulfate in the aqueous phase solution is 0.02 wt%. The oil phase solution consists of trimesoyl chloride and n-hexane; wherein the concentration of trimesoyl chloride in the oil phase solution is 0.175 wt%.

[0032] Step (3) In a mixed aqueous solution containing citric acid and ferrous sulfate, the ferrous ion concentration is 0.005% (w / v).

[0033] In step (4), the concentration of the antimicrobial functional monomer in the aqueous solution containing the antimicrobial functional monomer is 0.9% (w / v). Simultaneously, in step (4), the antimicrobial functional monomer is composed of carboxybetaine methacrylate, [2-(methacryloyloxy)ethyl]trimethylammonium chloride, methacrylated chitosan, and 3-allyl-5,5-dimethylhydantoin in a weight ratio of 55:25:12:8.

[0034] Example 2

[0035] A production process for an antimicrobial fouling reverse osmosis membrane differs from that in Example 1 in that... (3) The base film obtained in step (2) is dried at 40°C for 5 min and then immersed in a mixed aqueous solution containing citric acid and ferrous sulfate at 45°C for 20 min to obtain the activated film. (4) The activated membrane obtained in step (3) is directly immersed in an aqueous solution containing antimicrobial functional monomers without being washed, and hydrogen peroxide is added to make the hydrogen peroxide concentration 50 mg / L. Under nitrogen protection, it is treated at 50°C for 80 min to obtain a functionalized membrane.

[0036] Example 3

[0037] A production process for an antimicrobial fouling reverse osmosis membrane differs from that in Example 1 in that... (3) The base film obtained in step (2) is dried at 55°C for 3 min and then immersed in a mixed aqueous solution containing citric acid and ferrous sulfate at 60°C for 15 min to obtain the activated film. (4) The activated membrane obtained in step (3) is directly immersed in an aqueous solution containing antimicrobial functional monomers without being washed, and hydrogen peroxide is added to make the hydrogen peroxide concentration 200 mg / L. Under nitrogen protection, it is treated at 60°C for 50 min to obtain a functionalized membrane.

[0038] Example 4

[0039] A production process for an antimicrobial fouling reverse osmosis membrane differs from Example 1 in that the polyamine monomer is m-phenylenediamine, and its concentration in the aqueous solution is 2 wt%.

[0040] Example 5

[0041] A production process for an antimicrobial fouling reverse osmosis membrane differs from Example 1 in that the polyamine monomer is m-phenylenediamine, and its concentration in the aqueous solution is 5 wt%.

[0042] Example 6

[0043] A production process for an antimicrobial fouling reverse osmosis membrane, which differs from Example 1 in that the concentration of pyromellitic trimethylol chloride in the oil phase solution is 0.05 wt%.

[0044] Example 7

[0045] A production process for an antimicrobial fouling reverse osmosis membrane differs from Example 1 in that the concentration of pyromellitic trimethylol chloride in the oil phase solution is 0.3 wt%.

[0046] Example 8

[0047] A production process for an antimicrobial fouling reverse osmosis membrane differs from that in Example 1 in that, in step (3), the ferrous ion concentration in a mixed aqueous solution containing citric acid and ferrous sulfate is 0.001% (w / v).

[0048] Example 9

[0049] A production process for an antimicrobial fouling reverse osmosis membrane differs from Example 1 in that, in step (3), the ferrous ion concentration in a mixed aqueous solution containing citric acid and ferrous sulfate is 0.01% (w / v).

[0050] Example 10

[0051] A production process for an antimicrobial fouling reverse osmosis membrane differs from Example 1 in that, in step (4), the concentration of the antimicrobial functional monomer in the aqueous solution containing the antimicrobial functional monomer is 1.0% (w / v).

[0052] Example 11

[0053] A production process for an antimicrobial fouling reverse osmosis membrane differs from Example 1 in that, in step (4), the concentration of the antimicrobial functional monomer in the aqueous solution containing the antimicrobial functional monomer is 0.8% (w / v).

[0054] Example 12

[0055] A production process for an antimicrobial fouling reverse osmosis membrane differs from Example 1 in that the antimicrobial functional monomer is composed of carboxybetaine methacrylate, [2-(methacryloyloxy)ethyl]trimethylammonium chloride, methacrylated chitosan, and 3-allyl-5,5-dimethylhydantoin in a weight ratio of 7:3:1.25:1.

[0056] Example 13

[0057] A production process for an antimicrobial fouling reverse osmosis membrane differs from Example 1 in that the antimicrobial functional monomer is composed of carboxybetaine methacrylate, [2-(methacryloyloxy)ethyl]trimethylammonium chloride, methacrylated chitosan, and 3-allyl-5,5-dimethylhydantoin in a weight ratio of 6:2.5:1:1.

[0058] Example 14

[0059] A production process for an antimicrobial fouling reverse osmosis membrane differs from Example 1 in that the antimicrobial functional monomer is composed of carboxybetaine methacrylate, [2-(methacryloyloxy)ethyl]trimethylammonium chloride, methacrylated chitosan, and 3-allyl-5,5-dimethylhydantoin in a weight ratio of 8:3.5:1.5:1.

[0060] Example 15

[0061] A production process for an antimicrobial fouling reverse osmosis membrane differs from that in Example 1 in that step (5) is specifically set as follows: the functionalized membrane obtained in step (4) is first soaked in an aqueous solution containing vitamin C, then rinsed with deionized water, then immersed in an ethanol / water mixed solution containing 3-(4-vinylbenzyl)-5,5-dimethylhydantoin and glutaraldehyde, soaked at 37.5°C for 55 min, then rinsed with deionized water, then immersed in an aqueous glycerol solution for treatment, and finally dried to obtain an antimicrobial fouling reverse osmosis membrane; In an ethanol / water mixed solution containing 3-(4-vinylbenzyl)-5,5-dimethylhydantoin and glutaraldehyde, the concentration of 3-(4-vinylbenzyl)-5,5-dimethylhydantoin is 2% (w / v) and the concentration of glutaraldehyde is 0.55% (w / v).

[0062] Example 16

[0063] A production process for an antimicrobial fouling reverse osmosis membrane differs from that in Example 15 in that the membrane is immersed in an ethanol / water mixture containing 3-(4-vinylbenzyl)-5,5-dimethylhydantoin and glutaraldehyde for 60 minutes at 35°C.

[0064] Example 17

[0065] A production process for an antimicrobial fouling reverse osmosis membrane differs from that in Example 15 in that the membrane is immersed in an ethanol / water mixture containing 3-(4-vinylbenzyl)-5,5-dimethylhydantoin and glutaraldehyde for 50 minutes at 40°C.

[0066] Example 18

[0067] A production process for an antimicrobial fouling reverse osmosis membrane differs from Example 15 in that, in an ethanol / water mixed solution containing 3-(4-vinylbenzyl)-5,5-dimethylhydantoin and glutaraldehyde, the concentration of 3-(4-vinylbenzyl)-5,5-dimethylhydantoin is 2.1% (w / v) and the concentration of glutaraldehyde is 0.55% (w / v).

[0068] Example 19

[0069] A production process for an antimicrobial fouling reverse osmosis membrane differs from Example 15 in that, in an ethanol / water mixed solution containing 3-(4-vinylbenzyl)-5,5-dimethylhydantoin and glutaraldehyde, the concentration of 3-(4-vinylbenzyl)-5,5-dimethylhydantoin is 1.8% (w / v) and the concentration of glutaraldehyde is 0.4% (w / v).

[0070] Example 20

[0071] A production process for an antimicrobial fouling reverse osmosis membrane differs from Example 15 in that, in an ethanol / water mixed solution containing 3-(4-vinylbenzyl)-5,5-dimethylhydantoin and glutaraldehyde, the concentration of 3-(4-vinylbenzyl)-5,5-dimethylhydantoin is 2.4% (w / v) and the concentration of glutaraldehyde is 0.6% (w / v).

[0072] Example 21

[0073] A manufacturing process for an antimicrobial fouling reverse osmosis membrane, which differs from Example 15 in that 3-(4-vinylbenzyl)-5,5-dimethylhydantoin is not used.

[0074] Example 22

[0075] A manufacturing process for an antimicrobial fouling reverse osmosis membrane, which differs from Example 15 in that glutaraldehyde is not used.

[0076] Example 23

[0077] A production process for an antimicrobial fouling reverse osmosis membrane differs from that in Example 15 in that, in step (1), low molecular weight branched polyethyleneimine is added to the aqueous solution containing polyamine monomers. The amount of low molecular weight branched polyethyleneimine added is 7.5% of the mass of the polyamine monomers, and the Mw of the low molecular weight branched polyethyleneimine is 1200 Da.

[0078] Example 24

[0079] A production process for an antimicrobial fouling reverse osmosis membrane differs from that in Example 23 in that the amount of molecular weight branched polyethyleneimine added is 5% of the mass of the polyamine monomer.

[0080] Example 25

[0081] A production process for an antimicrobial fouling reverse osmosis membrane, which differs from Example 23 in that the amount of molecular weight branched polyethyleneimine added is 10% of the mass of the polyamine monomer.

[0082] Example 26

[0083] A production process for an antimicrobial fouling reverse osmosis membrane, which differs from Example 23 in that the Mw of the low molecular weight branched polyethyleneimine is 600 Da.

[0084] Example 27

[0085] A production process for an antimicrobial fouling reverse osmosis membrane, differing from Example 23, involves a low molecular weight branched polyethyleneimine with a molecular weight (Mw) of 1800 Da. Example 28

[0086] A production process for an antimicrobial fouling reverse osmosis membrane differs from Example 1 in that, in step (1), low molecular weight branched polyethyleneimine is added to the aqueous solution containing polyamine monomers. The amount of low molecular weight branched polyethyleneimine added is 7.5% of the mass of the polyamine monomers, and the Mw of the low molecular weight branched polyethyleneimine is 1200 Da.

[0087] Comparative Example Comparative Example 1 A manufacturing process for an antimicrobial fouling reverse osmosis membrane, which differs from Example 1, includes the following steps: (1) Immerse the base film in an aqueous solution containing polyamine monomers for 120s, then remove it and remove any residual liquid from the surface; (2) Immerse the base film obtained in step (1) in an oil phase solution containing trimesoyl chloride for 40 seconds, and remove it to remove the residual liquid on the surface; (3) The base membrane obtained in step (2) is dried at 47.5°C for 4 min, then immersed in a 20% glycerol aqueous solution for 5 min, and finally dried to obtain an antimicrobial fouling reverse osmosis membrane.

[0088] Comparative Example 2 A production process for an antimicrobial fouling reverse osmosis membrane differs from Example 1 in that only carboxybetaine methacrylate is used in the antimicrobial functional monomer.

[0089] Comparative Example 3 A production process for an antimicrobial fouling reverse osmosis membrane differs from Example 1 in that only [2-(methacryloyloxy)ethyl]trimethylammonium chloride is used in the antimicrobial functional monomer.

[0090] Comparative Example 4 A production process for an antimicrobial fouling reverse osmosis membrane differs from Example 1 in that only methacrylated chitosan is used in the antimicrobial functional monomer.

[0091] Comparative Example 5 A production process for an antimicrobial fouling reverse osmosis membrane differs from Example 1 in that only 3-allyl-5,5-dimethylhydantoin is used in the antimicrobial functional monomer.

[0092] Performance testing Test samples: Antimicrobial fouling reverse osmosis membranes obtained using the production process of antimicrobial fouling reverse osmosis membranes in Examples 1-28 were used as test samples 1-28, and antimicrobial fouling reverse osmosis membranes obtained using the production process of antimicrobial fouling reverse osmosis membranes in Comparative Examples 1-5 were used as control samples 1-5.

[0093] Test method: The permeation flux and desalination rate of the antimicrobial fouling reverse osmosis membrane were tested according to the operation in GB / T 32373-2025 "Test Method for Reverse Osmosis Membranes". The test operation conditions were: feed solution was 2000 ppm sodium chloride aqueous solution, solution pH was 7.5±0.5, operating pressure was 225 psi, and operating temperature was 25±1℃.

[0094] Then, the antimicrobial contamination reverse osmosis membrane was immersed in E. coli culture medium (CFU = 1 × 10⁻⁶). 6 The membrane was incubated at 37°C for 24 hours in a solution of 2000 ppm sodium chloride and 1000 ppm bovine serum albumin. The membrane was then gently washed with physiological saline to remove any unadhered bacteria. The feed solution was then used as the feed water solution. The membrane was continuously run at an operating pressure of 1.55 MPa and a temperature of 25 ± 1°C for 24 hours to obtain the antimicrobial fouling reverse osmosis membrane.

[0095] The permeation flux and desalination rate of the antimicrobial fouling reverse osmosis membrane after fouling were tested using the same method as described above, and the flux decline rate and desalination rate decline rate after fouling were calculated. After completing the above tests on test samples 1-28 and control samples 1-5, the test results were recorded in Table 1.

[0096] Table 1. Test results of test samples 1-28 and control samples 1-5

[0097] As can be seen from Examples 1-14 and Comparative Examples 1-5, and in conjunction with Table 1, this application ingeniously combines surface activation (CA-Fe) 2+ The combination of surface-limited Fenton initiation (with H2O2) and in-situ covalent graft copolymerization (four special monomer combinations) transforms the traditional "easily peelable physical coating layer" into a "functional layer integrated with the polyamide separation layer." This results in an antimicrobial fouling reverse osmosis membrane that, after the aforementioned tests, shows a significant reduction in both flux and desalination rate decline after fouling. Simultaneously, it was found that while individual use of any one of carboxybetaine methacrylate, [2-(methacryloyloxy)ethyl]trimethylammonium chloride, methacrylamide chitosan, and 3-allyl-5,5-dimethylhydantoin can improve flux and desalination rate decline after fouling compared to reverse osmosis membranes without antimicrobial functional monomers, the combined effect of their individual use is far less superior than that of their combined use.

[0098] As can be seen from Examples 1 and 15-22 and Table 1, this application uses 3-(4-vinylbenzyl)-5,5-dimethylhydantoin and glutaraldehyde in combination, which can achieve post-structural densification and functional enhancement treatment based on free radical grafting, thereby further reducing the flux decay rate and desalination rate decay rate after fouling obtained in the test. At the same time, it was found that 3-(4-vinylbenzyl)-5,5-dimethylhydantoin and glutaraldehyde can have a significant effect of 1+1>2, exerting excellent long-term antimicrobial stability and obtaining a high-quality antimicrobial fouling reverse osmosis membrane.

[0099] Combining Examples 15 and 23-27 with Table 1, it can be seen that by using low molecular weight branched polyethyleneimine to covalently embed into the forming polyamide network, and further strengthening the interfacial bonding between the functional layer and the PA separation layer with glutaraldehyde and 3-(4-vinylbenzyl)-5,5-dimethylhydantoin, the measured flux and desalination rate reduction rates after fouling are further reduced. Furthermore, combining Example 28 with Table 1, it can be seen that without the use of glutaraldehyde and 3-(4-vinylbenzyl)-5,5-dimethylhydantoin, the corresponding effects of using low molecular weight branched polyethyleneimine to covalently embed into the forming polyamide network are significantly diminished. Therefore, the synergy between these two ingredients can bring about significant improvements, significantly enhancing the long-term stability of the resulting antimicrobial fouling reverse osmosis membrane.

[0100] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A manufacturing process for an antimicrobial fouling reverse osmosis membrane, characterized in that, Includes the following steps: (1) Immerse the base film in an aqueous solution containing polyamine monomers for treatment, and remove it to remove any residual liquid from the surface; (2) Immerse the base film obtained in step (1) in an oil phase solution containing pyromellitic chloride, and remove it to remove the residual liquid on the surface; (3) Dry the base film obtained in step (2) at 40-55℃ for 3-5 min, and then immerse it in a mixed aqueous solution containing citric acid and ferrous sulfate at 45-60℃ for 15-20 min to obtain the activated film. (4) The activated membrane obtained in step (3) is directly immersed in an aqueous solution containing antimicrobial functional monomers without being washed, and hydrogen peroxide is added to make the hydrogen peroxide concentration 50-200 mg / L. Under nitrogen protection, it is treated at 50-60℃ for 50-80 min to obtain a functionalized membrane. (5) The functionalized membrane obtained in step (4) is first soaked in an aqueous solution containing vitamin C, then rinsed with deionized water, then immersed in an aqueous solution of glycerol for treatment, and finally dried to obtain an antimicrobial fouling reverse osmosis membrane. In step (4) above, the antimicrobial functional monomer is composed of carboxybetaine methacrylate, [2-(methacryloyloxy)ethyl]trimethylammonium chloride, methacrylated chitosan and 3-allyl-5,5-dimethylhydantoin in a weight ratio of (6-8):(2.5-3.5):(1-1.5):

1.

2. The production process of the antimicrobial fouling reverse osmosis membrane according to claim 1, characterized in that: The antimicrobial functional monomer is composed of carboxybetaine methacrylate, [2-(methacryloyloxy)ethyl]trimethylammonium chloride, methacrylated chitosan, and 3-allyl-5,5-dimethylhydantoin in a weight ratio of 55:25:12:

8.

3. The production process of the antimicrobial fouling reverse osmosis membrane according to claim 1, characterized in that: Step (3) In a mixed aqueous solution containing citric acid and ferrous sulfate, the ferrous ion concentration is 0.001%-0.01% (w / v).

4. The production process of the antimicrobial fouling reverse osmosis membrane according to claim 1, characterized in that: Step (4) In an aqueous solution containing antimicrobial functional monomers, the concentration of the antimicrobial functional monomers is 0.8%-1.0% (w / v).

5. The production process of the antimicrobial fouling reverse osmosis membrane according to claim 1, characterized in that: Step (5) is specifically set as follows: the functionalized membrane obtained in step (4) is first soaked in an aqueous solution containing vitamin C, then rinsed with deionized water, then immersed in an ethanol / water mixed solution containing 3-(4-vinylbenzyl)-5,5-dimethylhydantoin and glutaraldehyde, soaked at 35-40℃ for 50-60 min, then rinsed with deionized water, then immersed in an aqueous glycerol solution for treatment, and finally dried to obtain an antimicrobial fouling reverse osmosis membrane; In an ethanol / water mixed solution containing 3-(4-vinylbenzyl)-5,5-dimethylhydantoin and glutaraldehyde, the concentration of 3-(4-vinylbenzyl)-5,5-dimethylhydantoin is 1.8%-2.4% (w / v), and the concentration of glutaraldehyde is 0.4%-0.6% (w / v).

6. The production process of the antimicrobial fouling reverse osmosis membrane according to claim 5, characterized in that: In an ethanol / water mixed solution containing 3-(4-vinylbenzyl)-5,5-dimethylhydantoin and glutaraldehyde, the concentration of 3-(4-vinylbenzyl)-5,5-dimethylhydantoin is 2% (w / v) and the concentration of glutaraldehyde is 0.55% (w / v).

7. The production process of the antimicrobial fouling reverse osmosis membrane according to claim 5, characterized in that: Step (1) Low molecular weight branched polyethyleneimine is added to the aqueous solution containing polyamine monomers. The amount of low molecular weight branched polyethyleneimine added is 5%-10% of the mass of polyamine monomers, and the Mw of low molecular weight branched polyethyleneimine is 600-1800 Da.

8. The production process of the antimicrobial fouling reverse osmosis membrane according to claim 1, characterized in that: In step (1), the polyamine monomer is m-phenylenediamine, and its concentration in the aqueous solution is 2-5 wt%.

9. The production process of the antimicrobial fouling reverse osmosis membrane according to claim 1, characterized in that: In step (2), the concentration of pyromellitic chloride in the oil phase solution is 0.05-0.3wt%.

10. A reverse osmosis membrane resistant to microbial fouling, characterized in that: It is prepared using the production process of the antimicrobial fouling reverse osmosis membrane as described in any one of claims 1-9.

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