Preparation method of high-performance nanofiltration membrane by photo-initiated polymerization assisted interfacial polymerization

Abstract

This invention provides a method for preparing a high-performance nanofiltration membrane using photoinitiated polymerization-assisted interfacial polymerization, relating to the field of nanofiltration membrane preparation technology. The method includes the following steps: Step S1: Dissolving the acyl chloride monomer for the interfacial polymerization organic phase reaction in a non-polar organic solvent and then wetting the surface of a base membrane; Step S2: Under dark conditions, dissolving the functional monomer crosslinking agent, co-crosslinking agent, photoinitiator, and co-initiator separately in water, and then mixing them uniformly with the diamine monomer for the interfacial polymerization aqueous phase reaction to obtain a photoinitiated aqueous solution; Step S3: Spreading the photoinitiated aqueous solution evenly on the surface of the carrier membrane, and irradiating the photoinitiated aqueous solution on the carrier membrane with ultraviolet light and / or visible light; Step S4: Performing heat treatment on the composite membrane, and after sufficient coupling, allowing it to stand in water and then drying it to obtain a high-performance nanofiltration membrane using photoinitiated polymerization-assisted interfacial polymerization. This invention couples photoinitiated polymerization with interfacial polymerization, providing mild preparation conditions and simple reaction operations.

Description

Technical Field

[0001] This invention relates to the field of nanofiltration membrane preparation technology, and more specifically, to a method for preparing a high-performance nanofiltration membrane by photoinitiated polymerization-assisted interfacial polymerization. Background Technology

[0002] Nanofiltration, as a highly efficient membrane separation technology for water treatment, can effectively remove colloidal particles, bacteria, viruses, macromolecular organic matter, and inorganic salts, and has attracted much attention in seawater desalination, wastewater reuse, and drinking water production. Currently, the most widely used membrane composite polyamide nanofiltration membrane boasts high separation efficiency and low energy consumption. Its water flux is higher than reverse osmosis but still lower than ultrafiltration, and it suffers from issues such as an upper limit to the trade-off between permeability and selectivity, susceptibility to fouling, and poor stability. Modification methods such as surface coating, grafting, constructing intermediate layers, and adding nanomaterials are commonly used to improve the physicochemical properties of the polyamide separation layer, including hydrophilicity, surface electronegativity, pore size distribution, effective filtration area, and membrane thickness. This enhances the nanofiltration membrane's precise ion separation performance, strengthens the membrane surface's resistance to fouling, and improves the membrane's long-term operational stability. However, these modification methods typically require post-processing procedures outside of the membrane preparation process, making the modification process complex and demanding. For example, Zhang et al. (Separation and Purification Technology, 2022, 288:120710) showed that grafting methyl 2-aminobenzoate onto the membrane surface after interfacial polymerization enhances the membrane's resistance to biofouling, but significantly reduces its ability to remove inorganic salts. Wang et al. (Journal of Membrane Science, 2022, 650:120451) found that adding COF materials to the membrane preparation process can enhance the negative charge on the membrane surface and improve the removal of divalent anions; however, the raw materials for preparing COF materials are expensive, and the preparation process is complex. Therefore, finding simple, low-cost, and environmentally friendly membrane preparation and modification methods will be a major breakthrough for water treatment processes. Summary of the Invention

[0003] The problem solved by this invention is that the existing nanofiltration membrane preparation and modification process is complex, has high requirements for conditions, and uses expensive materials, resulting in high costs.

[0004] To address the above problems, this invention provides a method for preparing a high-performance nanofiltration membrane using photoinitiated polymerization-assisted interfacial polymerization, comprising the following steps:

[0005] Step S1: After dissolving the interfacial polymerization organic phase reaction acyl chloride monomer in a non-polar organic solvent, it is uniformly wetted onto the surface of the base film until the non-polar organic solvent is completely evaporated and the organic phase reaction acyl chloride monomer is uniformly distributed on the surface of the base film to obtain a carrier film.

[0006] Step S2: Under dark conditions, the functional monomer crosslinking agent, co-crosslinking agent, photoinitiator, and co-initiator are dissolved in water respectively, and then mixed evenly with the diamine monomer of the interfacial polymerization aqueous phase reaction to obtain a photoinitiated aqueous phase solution; the functional monomer crosslinking agent contains specific functional groups and unsaturated bonds, wherein the specific functional groups include one or more of sulfonyl, amide, carbonyl, ester, quaternary ammonium, hydroxyl, epoxy, and carbon-fluorine (CF) bonds;

[0007] Step S3: Spread the photoinitiated aqueous solution evenly on the surface of the carrier membrane after the treatment in step S1, irradiate the photoinitiated aqueous solution on the carrier membrane with ultraviolet light and / or visible light to induce interfacial polymerization and photoinitiated polymerization, then remove the liquid on the surface of the carrier membrane, turn off the light source, and obtain the composite membrane;

[0008] Step S4: The composite membrane from step S3 is heat-treated to fully couple the interfacial polymerization reaction and the photo-initiated polymerization reaction. The composite membrane is then left to stand in ultrapure water and dried at room temperature to obtain a high-performance nanofiltration membrane with photo-initiated polymerization-assisted interfacial polymerization.

[0009] Further, in step S1, the concentration of the acyl chloride monomer in the interfacial polymerization organic phase reaction is 0.1-1 wt%; the nonpolar organic solvent includes one or more of n-pentane, n-hexane, cyclohexane, n-heptane, and n-octane.

[0010] Further, in step S2, the photoinitiator includes aromatic alkyl ketones or aromatic ketones, wherein the aromatic alkyl ketones include one or more of benzoin, benzoyl, acetophenone and its derivatives, α-hydroxy ketones, α-amino ketones and acylphosphine oxides; and the aromatic ketones include one or more of benzophenone, thioxanthone, anthraquinone, coumarin and camphorquinone.

[0011] Further, in step S2, the co-initiator is a tertiary amine compound containing active hydrogen, including one or more of aliphatic tertiary amines, tertiary amine benzoates, ethanolamine tertiary amines, and active amines.

[0012] Further, in step S2, the functional monomer crosslinking agent includes one or more of 2-acrylamido-2-methyl-1-propanesulfonic acid, N,N-methylenebisacrylamide, 3-allyl-5,5-dimethylhydantoin, 2,2,3,4,4,4-hexafluorobutyl methacrylate, acrylamide, 2-hydroxyethyl acrylate, [2-(methacryloyloxy)ethyl]trimethylammonium chloride, vinyl sulfonic acid, glycidyl methacrylate, and trimethylolpropane acrylate.

[0013] Further, in step S2, the interfacial polymerization aqueous phase reaction diamine monomer includes one or more of N,N-diaminopiperazine, N-(2-aminoethyl)-piperazine, 3,5-diaminobenzoylpiperazine, 4-aminobenzoylpiperazine, and 3-aminobenzoylpiperazine.

[0014] Further, in step S3, the ultraviolet light and / or visible light comes from a xenon lamp, and the irradiance is 75-600 mW / cm². 2 The irradiation time is 0.5-8 minutes.

[0015] Furthermore, in step S4, the temperature of the heat treatment includes 40-70°C, and the time of the heat treatment includes 5-10 minutes.

[0016] Furthermore, in step S4, the composite membrane is left to stand in ultrapure water for 0.5-2 minutes.

[0017] Further, in step S1, the base film includes one or more of polysulfone, polyethersulfone, polyvinylidene fluoride, or polyvinyl chloride, and the molecular weight cutoff of the base film is 50kDa-150kDa.

[0018] The advantages of the photo-initiated polymerization-assisted interfacial polymerization high-performance nanofiltration membrane preparation method described in this invention compared to existing technologies lie in the fact that this invention mixes a functional monomer crosslinking agent with specific functional groups and unsaturated bonds with diamine monomers for interfacial polymerization in the aqueous phase and acyl chloride monomers for organic phase reaction at the reaction interface. The photo-initiated aqueous solution on the carrier membrane is irradiated with ultraviolet and / or visible light, causing interfacial polymerization and photo-initiated polymerization reactions. During the synergistic reaction of interfacial polymerization and photo-initiated polymerization, the functional monomer crosslinking agent crosslinks with the polyamide network structure to form a photo-initiated polymerization-assisted interfacial polymerization high-performance nanofiltration membrane. Specific functional groups achieve specific chemical modification of the nanofiltration membrane, altering the hydrophilicity and electrophilicity of the membrane surface and pore interior, while simultaneously improving the uniformity of pore distribution and the crosslinking density within the membrane, enhancing the permeability and selective separation performance of the nanofiltration membrane, improving the membrane's removal of pollutants and its anti-fouling ability, and simultaneously improving chlorine resistance. The preparation process of this invention is simplified, coupling photo-initiated polymerization and interfacial polymerization without additional steps, with mild preparation conditions and simple reaction operation. Attached Figure Description

[0019] Figure 1 In the figures, a and b are scanning electron microscope images of the photo-initiated polymerization-assisted interfacial polymerization high-performance nanofiltration membrane of Example 1 and the nanofiltration membrane of Control Example 1, respectively.

[0020] Figure 2 a and b in the figure are atomic force microscopy images of the high-performance nanofiltration membrane of photoinitiated polymerization-assisted interfacial polymerization in Example 1 and the nanofiltration membrane of control Example 2, respectively.

[0021] Figure 3 Fourier transform infrared spectra of a control nanofiltration membrane and a high-performance nanofiltration membrane produced by photoinitiated polymerization-assisted interfacial polymerization are shown in the comparison diagram.

[0022] Figure 4 This is a comparison diagram of the water permeability of a nanofiltration membrane and a high-performance nanofiltration membrane produced by photoinitiated polymerization-assisted interfacial polymerization.

[0023] Figure 5 A comparison chart of salt removal rates between a control nanofiltration membrane and a photoinitiated polymerization-assisted interfacial polymerization high-performance nanofiltration membrane;

[0024] Figure 6 This is a comparison chart of pollutant removal rates between a nanofiltration membrane and a high-performance nanofiltration membrane with photoinitiated polymerization-assisted interfacial polymerization. Detailed Implementation

[0025] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0026] This invention provides a method for preparing a high-performance nanofiltration membrane using photoinitiated polymerization-assisted interfacial polymerization, comprising the following steps:

[0027] Step S1: After dissolving the interfacial polymerization organic phase reaction acyl chloride monomer in a non-polar organic solvent, it is uniformly wetted onto the surface of the base film until the non-polar organic solvent is completely evaporated and the organic phase reaction acyl chloride monomer is uniformly distributed on the surface of the base film to obtain a carrier film.

[0028] Step S2: Under dark conditions, the functional monomer crosslinking agent, co-crosslinking agent, photoinitiator, and co-initiator are dissolved in water respectively, and then mixed evenly with the diamine monomer of the interfacial polymerization aqueous phase reaction to obtain a photoinitiated aqueous phase solution; the functional monomer crosslinking agent contains specific functional groups and unsaturated bonds, wherein the specific functional groups include one or more of sulfonyl, amide, carbonyl, ester, quaternary ammonium, hydroxyl, epoxy, and carbon-fluorine bond (CF);

[0029] Step S3: Spread the photoinitiated aqueous solution evenly on the surface of the carrier membrane after the treatment in step S1, irradiate the photoinitiated aqueous solution on the carrier membrane with ultraviolet light and / or visible light to induce interfacial polymerization and photoinitiated polymerization, then remove the liquid on the surface of the carrier membrane, turn off the light source, and obtain the composite membrane;

[0030] Step S4: The composite membrane from step S3 is heat-treated to fully couple the interfacial polymerization reaction and the photo-initiated polymerization reaction. The composite membrane is then left to stand in ultrapure water and dried at room temperature to obtain a high-performance nanofiltration membrane with photo-initiated polymerization-assisted interfacial polymerization.

[0031] This invention mixes a functional monomer crosslinking agent with specific functional groups and unsaturated bonds with diamine monomers for interfacial polymerization in the aqueous phase and acyl chloride monomers for organic phase polymerization at the reaction interface. The aqueous solution on the carrier membrane is then irradiated with ultraviolet and / or visible light to initiate interfacial polymerization and photo-initiated polymerization. During the synergistic reaction of interfacial and photo-initiated polymerization, the functional monomer crosslinking agent crosslinks with the polyamide network structure, forming a high-performance nanofiltration membrane with photo-initiated polymerization-assisted interfacial polymerization. The specific functional groups achieve specific chemical modification of the nanofiltration membrane, altering the hydrophilicity and electrophilicity of the membrane surface and pore interior, while simultaneously improving the uniformity of pore distribution and the crosslinking density within the membrane. This enhances the permeability and selective separation performance of the nanofiltration membrane, improves its ability to remove pollutants and its anti-fouling capacity, and also increases its chlorine resistance. The method described in this invention simplifies the preparation process, coupling photo-initiated polymerization and interfacial polymerization without requiring additional steps, and the preparation conditions are mild and the reaction operation is simple.

[0032] Specifically, in step S1, the acyl chloride monomer of the interfacial polymerization organic phase reaction is dissolved in a non-polar organic solvent to prepare a reaction organic phase solution. The organic phase solution is then uniformly injected onto the surface of the base membrane using a syringe, so that the surface of the base membrane is uniformly wetted with a layer of reaction organic phase monomers until the non-polar organic solvent is completely evaporated. The organic phase monomer molecules are uniformly distributed on the surface of the base membrane, and some of them enter the pores of the base membrane to form a carrier membrane.

[0033] Specifically, in step S2, a photoinitiated polymerization solution is prepared. Under dark conditions, the functional monomer crosslinking agent and co-crosslinking agent are first dissolved in a certain amount of water, and the dissolution is assisted by ultrasound. Then, the photoinitiator and co-initiator are dissolved separately in water and fully dissolved for later use. The diamine monomer for the interfacial polymerization aqueous phase reaction is dissolved in the crosslinking agent solution. Then, the crosslinking agent solution and the photoinitiator solution are thoroughly mixed. The resulting solution is then rapidly mixed with the co-initiator solution until fully homogeneous to obtain the photoinitiated aqueous phase solution. Functional monomer crosslinking agents contain specific functional groups and unsaturated bonds. Among them, the specific functional groups include one or more of sulfonyl, amide, carbonyl, ester, quaternary ammonium, hydroxyl, epoxy, and carbon-fluorine (CF) bonds. In the synergistic reaction of interfacial polymerization and photoinitiated polymerization, the functional monomer crosslinking agent crosslinks with the polyamide network structure to form a high-performance nanofiltration membrane with photoinitiated polymerization-assisted interfacial polymerization. The specific functional groups achieve specific chemical modification of the nanofiltration membrane, changing the hydrophilicity and electrical properties of the membrane surface and the interior of the membrane pores. At the same time, it improves the uniformity of pore distribution and the crosslinking density inside the membrane, enhances the permeability and selective separation performance of the nanofiltration membrane, improves the membrane's ability to remove pollutants and its antifouling ability, and improves chlorine resistance.

[0034] Specifically, in step S3, the photoinitiating aqueous solution is thoroughly spread on the surface of the carrier membrane treated in step S1 using a syringe. The photoinitiating aqueous solution on the carrier membrane is then irradiated with ultraviolet and / or visible light, initiating the photoinitiated polymerization reaction simultaneously with the interfacial polymerization reaction. When the reaction interface is irradiated with ultraviolet light, the photoinitiator is excited, breaking bonds and generating active organic free radicals, stimulating the cross-linking polymerization of unsaturated bonds. When the reaction interface is irradiated with visible light, the photoinitiator and co-initiator interact, transferring electrons and protons, stimulating the co-initiator to generate active organic free radicals, and causing the unsaturated bonds to undergo cross-linking polymerization. Interfacial polymerization and photoinitiated polymerization occur simultaneously, and unsaturated monomers or oligomers cross-link with acyl chloride and amine groups, forming a light-mediated polymerized polyamide network, thus achieving chemical modification of the nanofiltration membrane.

[0035] Specifically, in step S4, the modified composite membrane from step S3 is heat-treated to fully couple the interfacial polymerization reaction and the photo-initiated polymerization reaction. The modified composite membrane is then taken out and left to stand in ultrapure water for a period of time. After that, it is taken out and left to dry at room temperature. When the visible bubbles on the surface disappear and the membrane is fully attached, a high-performance nanofiltration membrane with photo-initiated polymerization-assisted interfacial polymerization is obtained.

[0036] The principle of photopolymerization reaction in this embodiment of the invention is as follows:

[0037] Under ultraviolet or visible light irradiation, photoinitiators absorb photon energy and, upon excitation, undergo electron transitions and bond breaking, forming free radicals or cations. In the presence of monomers or oligomers containing unsaturated bonds, the formed free radicals or cations can initiate the breaking of unsaturated bonds, leading to polymerization. Based on the different mechanisms of free radical formation, photoinitiators can be classified into Type I and Type II photoinitiators. Type I photoinitiators are cleavage-type photoinitiators, typically responsive to the ultraviolet wavelength range. Under ultraviolet irradiation, Type I photoinitiators themselves cleave, forming free radical pairs. Type II photoinitiators are hydrogen-abstraction-type photoinitiators, typically responsive to both the ultraviolet and visible light regions. They require a hydrogen donor and co-initiator to interact and generate free radicals. Under ultraviolet or visible light irradiation, Type II photoinitiators are excited from the ground state to a singlet excited state, and then converted to a triplet excited state through intersystem transitions. The triplet excited state photoinitiator interacts with the hydrogen donor, resulting in electron transfer from the hydrogen donor to the photoinitiator and proton extraction. The co-initiator is then responsible for generating free radicals to initiate polymerization.

[0038] In some specific embodiments, in step S1, the concentration of the acyl chloride monomer in the interfacial polymerization organic phase reaction is 0.1-1 wt%; the nonpolar organic solvent includes one or more of n-pentane, n-hexane, cyclohexane, n-heptane, and n-octane. This facilitates the uniform distribution of the reactant monomers containing acyl chloride groups on the substrate film surface.

[0039] In some specific embodiments, in step S2, the photoinitiator includes aromatic alkyl ketones or aromatic ketones. The aromatic alkyl ketones include one or more of benzoin, benzoyl, acetophenone and its derivatives, α-hydroxy ketones, α-amino ketones, and acylphosphine oxides; the aromatic ketones include one or more of benzophenone, thioxanthone, anthraquinone, coumarone, and camphorquinone. Aromatic alkyl ketones can be used alone and belong to type I photoinitiators; aromatic ketones need to be used in conjunction with a hydrogen donor co-initiator, i.e., they are type II photoinitiators as described above. This provides the reaction basis for the photoinitiated polymerization reaction.

[0040] In some specific embodiments, in step S2, the co-initiator is a tertiary amine compound containing active hydrogen, including one or more of aliphatic tertiary amines, tertiary amine benzoates, ethanolamine tertiary amines, and active amines. Thus, the co-initiator, acting in conjunction with the type II photoinitiator, causes electron transfer from the hydrogen donor to the photoinitiator and proton extraction, thereby generating a free radical-initiated photoinitiated polymerization reaction.

[0041] In some specific embodiments, in step S2, the functional monomer crosslinking agent includes one or more of 2-acrylamido-2-methyl-1-propanesulfonic acid, N,N-methylenebisacrylamide, 3-allyl-5,5-dimethylhydantoin, 2,2,3,4,4,4-hexafluorobutyl methacrylate, acrylamide, 2-hydroxyethyl acrylate, [2-(methacryloyloxy)ethyl]trimethylammonium chloride, vinyl sulfonic acid, glycidyl methacrylate, and trimethylolpropane acrylate.

[0042] In some specific embodiments, in step S2, the interfacial polymerization aqueous phase reaction diamine monomer includes one or more of N,N-diaminopiperazine, N-(2-aminoethyl)-piperazine, 3,5-diaminobenzoylpiperazine, 4-aminobenzoylpiperazine, and 3-aminobenzoylpiperazine.

[0043] In some specific embodiments, in step S3, the ultraviolet light and / or visible light comes from a xenon lamp, and the irradiance is 75-600 mW / cm². 2 The irradiation time is 0.5-8 minutes. Sufficient irradiation allows the photoinitiator to absorb enough photon energy, causing electron transitions and bond breaking upon excitation, forming free radicals or cations, which in turn initiate the breaking of unsaturated bonds and a polymerization reaction.

[0044] In some specific embodiments, in step S4, the heat treatment temperature includes 40-70°C, and the heat treatment time includes 5-10 minutes. This promotes sufficient coupling between the photoinitiated polymerization reaction and the interfacial polymerization reaction.

[0045] In some specific embodiments, in step S4, the composite membrane is left to stand in ultrapure water for 0.5-2 minutes.

[0046] In some specific embodiments, in step S1, the base film includes one or more of polysulfone, polyethersulfone, polyvinylidene fluoride, or polyvinyl chloride, and the molecular weight cutoff of the base film is 50kDa-150kDa.

[0047] Example 1

[0048] The method for preparing a high-performance nanofiltration membrane using photoinitiated polymerization-assisted interfacial polymerization in this invention includes the following steps:

[0049] Step S1: Dissolve 0.1g of trimesoyl chloride in a brown bottle containing 99.9g of n-hexane, stir for 30min to completely dissolve the solute, and obtain an organic phase solution with a mass fraction of 0.1wt%. Spread the organic phase solution orderly on the surface of the base membrane by injecting it with a syringe, so that the surface of the base membrane is uniformly wetted with a layer of reactive organic phase monomers. Treat for a period of time until the non-polar organic solvent completely evaporates, the organic phase monomer molecules are uniformly distributed on the surface of the base membrane, and some enter the pores of the base membrane to obtain the carrier membrane.

[0050] Step S2: Prepare the photoinitiated polymerization solution under dark conditions. Dissolve 4.5g of 2-acrylamido-2-methyl-1-propanesulfonic acid and 0.03g of N,N-methylenebisacrylamide in 100ml of ultrapure water and sonicate to ensure complete dissolution. Then, dissolve 0.06g of vitamin B2 in 100ml of water and 7.5ml of triethylamine in 100ml of water and dissolve thoroughly for later use. Weigh 1.5g of piperazine and 2.4g of sodium bicarbonate and dissolve them in the crosslinking agent solution. Then, mix the crosslinking agent solution and the photoinitiator solution thoroughly. Quickly mix the above solution with the co-initiator solution until fully homogeneous to obtain the photoinitiated aqueous phase solution.

[0051] Step S3: The photoinitiating aqueous solution is spread evenly on the surface of the carrier membrane treated in step S1 using a syringe. A visible light irradiation lamp is placed above the reaction vessel to irradiate the reaction interface, initiating the photoinitiated polymerization reaction simultaneously with the interfacial polymerization reaction. The visible light wavelength is 450 nm and the irradiation intensity is 150 mW / cm². 2 The visible light irradiation time of the polymerization reaction interface is 5 minutes; after 5 minutes of reaction, the residual liquid on the surface of the carrier membrane is poured off to obtain the composite membrane, and then the light source is turned off.

[0052] Step S4: Place the reaction vessel in a forced-air drying oven for 10 minutes to ensure full coupling of the interfacial polymerization and photo-initiated polymerization reactions. Then, remove the reaction vessel, take out the composite membrane, and place it in ultrapure water for 2 minutes. Remove it again and allow it to dry at room temperature until the visible small bubbles on the surface of the composite membrane disappear and the upper polyamide layer is completely adhered to the base membrane, thus obtaining a high-performance nanofiltration membrane obtained from photo-initiated polymerization-assisted interfacial polymerization. Store it in ultrapure water for subsequent characterization and performance evaluation.

[0053] Scanning electron microscope (SEM) and atomic force microscope (AFM) images of photo-initiated polymerization-assisted interfacial polymerization high-performance nanofiltration membranes are shown below. Figure 1 a and Figure 2 a. The scanning electron microscope (SEM) and atomic force microscope (AFM) images of the nanofiltration membrane are shown below. Figure 1 b and Figure 2 b. As can be seen from the comparison, the high-performance nanofiltration membrane with photo-initiated polymerization-assisted interfacial polymerization has an interlaced striped surface structure and a greater surface roughness than the control nanofiltration membrane with tiny protruding nodules. This is because under light irradiation, the thermodynamic state of the component molecules in the reaction interface region changes, increasing the diffusion rate to the reaction interface, accelerating the interfacial polymerization process, promoting exothermic reactions and the release of gases during the reaction, causing the polyamide separation layer formed during the reaction to bulge out, forming an interlaced striped morphology and increasing the roughness.

[0054] Fourier transform infrared spectroscopy results of photo-initiated polymerization-assisted interfacial polymerization high-performance nanofiltration membrane and control nanofiltration membrane are as follows: Figure 3 As shown.

[0055] Flux and salt rejection of photo-initiated polymerization-assisted interfacial polymerization high-performance nanofiltration membrane and control nanofiltration membrane for pure water, sodium sulfate (Na₂SO₄), magnesium sulfate (MgSO₄), sodium chloride (NaCl), and magnesium chloride (MgCl₂) solutions (all at 2000 mg / L) are shown in the figure. Figure 4 and Figure 5 As shown.

[0056] The removal rates of trace organic pollutants atrazine, sulfamethoxazole, ciprofloxacin, tetracycline hydrochloride, and chloroquine phosphate by photo-initiated polymerization-assisted interfacial polymerization high-performance nanofiltration membrane and control nanofiltration membrane are as follows: Figure 6 As shown.

[0057] Example 2

[0058] The method for preparing a high-performance nanofiltration membrane using photoinitiated polymerization-assisted interfacial polymerization in this invention includes the following steps:

[0059] Step S1: Dissolve 0.1g of trimesoyl chloride in a brown bottle containing 99.9g of n-hexane, stir for 30min to completely dissolve the solute, and obtain an organic phase solution with a mass fraction of 0.1wt%. Spread the organic phase solution orderly on the surface of the base membrane by injecting it with a syringe, so that the surface of the base membrane is uniformly wetted with a layer of reactive organic phase monomers. Treat for a period of time until the non-polar organic solvent completely evaporates, the organic phase monomer molecules are uniformly distributed on the surface of the base membrane, and some enter the pores of the base membrane to obtain the carrier membrane.

[0060] Step S2: Prepare the photoinitiated polymerization solution under dark conditions. Dissolve 4.5g of 2,2,3,4,4,4-hexafluorobutyl methacrylate and 0.03g of acrylamide in 100ml of ultrapure water and sonicate to ensure complete dissolution. Then, dissolve 0.06g of sodium vitamin B2 phosphate in 100ml of water and 7.5ml of triethylamine in 100ml of water, and dissolve them thoroughly for later use. Weigh 1.5g of piperazine and 2.4g of sodium bicarbonate and dissolve them in the crosslinking agent solution. Then, mix the crosslinking agent solution and the photoinitiator solution thoroughly. Quickly mix the above solution with the co-initiator solution until fully homogeneous to obtain the photoinitiated aqueous phase solution.

[0061] Step S3: The photoinitiating aqueous solution is spread evenly on the surface of the carrier membrane treated in step S1 using a syringe. A visible light irradiation lamp is placed above the reaction vessel to irradiate the reaction interface, initiating the photoinitiated polymerization reaction simultaneously with the interfacial polymerization reaction. The visible light wavelength is 450 nm and the irradiation intensity is 600 mW / cm². 2 The visible light irradiation time of the polymerization reaction interface is 2 minutes; after 2 minutes of reaction, the residual liquid on the membrane surface is poured off to obtain the composite membrane, and then the light source is turned off.

[0062] Step S4: Place the reaction vessel in a forced-air drying oven for 10 minutes to ensure full coupling of the interfacial polymerization and photo-initiated polymerization reactions. Then, remove the reaction vessel, take out the composite membrane, and place it in ultrapure water for 2 minutes. Remove it again and allow it to dry at room temperature until the visible small bubbles on the surface of the composite membrane disappear and the upper polyamide layer is completely adhered to the base membrane, thus obtaining a high-performance nanofiltration membrane obtained from photo-initiated polymerization-assisted interfacial polymerization. Store it in ultrapure water for subsequent characterization and performance evaluation.

[0063] Example 3

[0064] The method for preparing a high-performance nanofiltration membrane using photoinitiated polymerization-assisted interfacial polymerization in this invention includes the following steps:

[0065] Step S1: Dissolve 0.1g of trimesoyl chloride in a brown bottle containing 99.9g of n-hexane, stir for 30min to completely dissolve the solute, and obtain an organic phase solution with a mass fraction of 0.1wt%. Spread the organic phase solution orderly on the surface of the base membrane by injecting it with a syringe, so that the surface of the base membrane is uniformly wetted with a layer of reactive organic phase monomers. Treat for a period of time until the non-polar organic solvent completely evaporates, the organic phase monomer molecules are uniformly distributed on the surface of the base membrane, and some enter the pores of the base membrane to obtain the carrier membrane.

[0066] Step S2: Prepare the photoinitiated polymerization solution under dark conditions. Dissolve 4.5g of 3-allyl-5,5-dimethylhydantoin and 0.03g of 2-hydroxyethyl acrylate in 100ml of ultrapure water and sonicate to ensure complete dissolution. Then, dissolve 0.06g of Iracge2959 in 100ml of water and set aside. Weigh 1.5g of piperazine and 2.4g of sodium bicarbonate and dissolve them in the crosslinking agent solution. Then, thoroughly mix the crosslinking agent solution with the photoinitiator solution. Quickly mix the above solution with the co-initiator solution until fully homogeneous to obtain the photoinitiated aqueous solution.

[0067] Step S3: The photoinitiating aqueous solution is spread evenly on the surface of the carrier membrane treated in step S1 using a syringe. An ultraviolet irradiation lamp is placed above the reaction vessel to irradiate the reaction interface, initiating the photoinitiated polymerization reaction simultaneously with the interfacial polymerization reaction. The ultraviolet light wavelength is 276 nm and the irradiation intensity is 75 mW / cm². 2 The interface polymerization reaction was carried out under visible light irradiation for 8 minutes. After 8 minutes of reaction, the residual liquid on the membrane surface was poured off to obtain a composite membrane. Then the light source was turned off.

[0068] Step S4: Place the reaction vessel in a forced-air drying oven for 10 minutes to ensure full coupling of the interfacial polymerization and photo-initiated polymerization reactions. Then, remove the reaction vessel, take out the composite membrane, and place it in ultrapure water for 2 minutes. Remove it again and allow it to dry at room temperature until the visible small bubbles on the surface of the composite membrane disappear and the upper polyamide layer is completely adhered to the base membrane, thus obtaining a high-performance nanofiltration membrane obtained from photo-initiated polymerization-assisted interfacial polymerization. Store it in ultrapure water for subsequent characterization and performance evaluation.

[0069] Example 4

[0070] The method for preparing a high-performance nanofiltration membrane using photoinitiated polymerization-assisted interfacial polymerization in this invention includes the following steps:

[0071] Step S1: Dissolve 0.1g of trimesoyl chloride in a brown bottle containing 99.9g of n-hexane, stir for 30min to completely dissolve the solute, and obtain an organic phase solution with a mass fraction of 0.1wt%. Spread the organic phase solution orderly on the surface of the base membrane by injecting it with a syringe, so that the surface of the base membrane is uniformly wetted with a layer of reactive organic phase monomers. Treat for a period of time until the non-polar organic solvent completely evaporates, the organic phase monomer molecules are uniformly distributed on the surface of the base membrane, and some enter the pores of the base membrane to obtain the carrier membrane.

[0072] Step S2: Prepare the photoinitiated polymerization solution under dark conditions. Dissolve 4.5g of [2-(methacryloyloxy)ethyl]trimethylammonium chloride and 0.03g of vinyl sulfonic acid in 100ml of ultrapure water and sonicate to ensure complete dissolution. Then, dissolve 0.06g of eosin Y in 100ml of water and set aside. Weigh 1.5g of piperazine and 2.4g of sodium bicarbonate and dissolve them in the crosslinking agent solution. Then, thoroughly mix the crosslinking agent solution with the photoinitiator solution. Quickly mix the above solution with the co-initiator solution until fully homogeneous to obtain the photoinitiated aqueous solution.

[0073] Step S3: Place a visible light irradiation lamp above the reaction vessel to irradiate the reaction interface, simultaneously initiating the photo-initiated polymerization reaction during the interfacial polymerization reaction. The visible light wavelength is 514 nm and the irradiation intensity is 150 mW / cm². 2 The interface polymerization reaction was carried out under visible light irradiation for 5 minutes; after 5 minutes of reaction, the residual liquid on the membrane surface was poured off to obtain a composite membrane, and then the light source was turned off.

[0074] Step S4: Place the reaction vessel in a forced-air drying oven for 10 minutes to ensure full coupling of the interfacial polymerization and photo-initiated polymerization reactions. Then, remove the reaction vessel, take out the composite membrane, and place it in ultrapure water for 2 minutes. Remove it again and allow it to dry at room temperature until the visible small bubbles on the surface of the composite membrane disappear and the upper polyamide layer is completely adhered to the base membrane, thus obtaining a high-performance nanofiltration membrane obtained from photo-initiated polymerization-assisted interfacial polymerization. Store it in ultrapure water for subsequent characterization and performance evaluation.

[0075] Compare with Example 1

[0076] Step T1: Dissolve 0.1g of trimesoyl chloride in a brown bottle containing 99.9g of n-hexane, stir for 30min to completely dissolve the solute, and obtain an organic phase solution with a mass fraction of 0.1wt%. Spread the organic phase solution orderly on the surface of the base membrane by injecting it with a syringe, so that the surface of the base membrane is uniformly wetted with a layer of reactive organic phase monomers. Treat for a period of time until the non-polar organic solvent completely evaporates, the organic phase monomer molecules are uniformly distributed on the surface of the base membrane, and some enter the pores of the base membrane to obtain the carrier membrane.

[0077] Step T2: Weigh 0.5g piperazine and 0.8g sodium bicarbonate and dissolve them in 100ml of water. Mix thoroughly to obtain an aqueous solution.

[0078] Step T3: Spread the aqueous solution evenly on the surface of the carrier membrane treated in step T1 using a syringe and react for 5 minutes. Then, pour off the residual liquid on the surface of the carrier membrane to obtain a composite membrane. Place the reaction vessel in a forced-air drying oven for heat treatment for 10 minutes to allow the interfacial polymerization reaction to proceed fully. Then, remove the reaction vessel and take out the composite membrane and let it stand in ultrapure water to obtain a high-performance nanofiltration separation membrane. Store it in ultrapure water for subsequent characterization and performance evaluation.

[0079] Compare with Example 2

[0080] Step T1: Dissolve 0.1g of trimesoyl chloride in a brown bottle containing 99.9g of n-hexane, stir for 30min to completely dissolve the solute, and obtain an organic phase solution with a mass fraction of 0.1wt%. Spread the organic phase solution orderly on the surface of the base membrane by injecting it with a syringe, so that the surface of the base membrane is uniformly wetted with a layer of reactive organic phase monomers. Treat for a period of time until the non-polar organic solvent completely evaporates, the organic phase monomer molecules are uniformly distributed on the surface of the base membrane, and some enter the pores of the base membrane to obtain the carrier membrane.

[0081] Step T2: Weigh 0.5g piperazine and 0.8g sodium bicarbonate and dissolve them in 100ml of water. Mix thoroughly to obtain an aqueous solution.

[0082] Step T3: The aqueous solution is spread evenly on the surface of the carrier membrane treated in Step T1 using a syringe. A visible light irradiation lamp is placed above the reaction vessel to irradiate the reaction interface, initiating photo-initiated polymerization simultaneously with the interfacial polymerization reaction. The visible light wavelength is 450 nm and the irradiation intensity is 150 mW / cm². 2 The interface polymerization reaction was irradiated with visible light for 5 minutes. After 5 minutes of reaction, the residual liquid on the membrane surface was poured off to obtain a composite membrane. Then the light source was turned off.

[0083] Step T4: Place the reaction vessel in a forced-air drying oven for 10 minutes to ensure the reaction proceeds fully. Then, remove the reaction vessel, take out the composite membrane, and let it stand in ultrapure water for 2 minutes. After that, remove it and let it dry at room temperature until the visible small bubbles on the membrane surface disappear and the upper polyamide layer is completely adhered to the base membrane, thus obtaining a high-performance nanofiltration membrane. Store it in ultrapure water for subsequent characterization and performance evaluation.

[0084] The water and inorganic salt selectivity tests were performed on Examples 1-4 and Control Examples 1-2, as shown in Table 1:

[0085] Table 1

[0086]

[0087] While the present invention has been disclosed above, its scope of protection is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and all such changes and modifications will fall within the scope of protection of the present invention.

Claims

1. A method for preparing a high-performance nanofiltration membrane using photoinitiated polymerization-assisted interfacial polymerization, characterized in that, Includes the following steps: Step S1: After dissolving the interfacial polymerization organic phase reaction acyl chloride monomer in a non-polar organic solvent, it is uniformly wetted onto the surface of the base film until the non-polar organic solvent is completely evaporated and the organic phase reaction acyl chloride monomer is uniformly distributed on the surface of the base film to obtain a carrier film. Step S2: Under dark conditions, the functional monomer crosslinking agent, co-crosslinking agent, photoinitiator, and co-initiator are dissolved in water respectively, and then mixed evenly with the diamine monomer of the interfacial polymerization aqueous phase reaction to obtain a photoinitiated aqueous phase solution; the functional monomer crosslinking agent contains specific functional groups and unsaturated bonds, wherein the specific functional groups include one or more of sulfonyl, amide, carbonyl, ester, quaternary ammonium, hydroxyl, epoxy, and carbon-fluorine (CF) bonds; Step S3: Spread the photoinitiated aqueous solution evenly on the surface of the carrier membrane after the treatment in step S1, irradiate the photoinitiated aqueous solution on the carrier membrane with ultraviolet light and / or visible light to induce interfacial polymerization and photoinitiated polymerization, then remove the liquid on the surface of the carrier membrane, turn off the light source, and obtain the composite membrane; Step S4: The composite membrane from step S3 is heat-treated to fully couple the interfacial polymerization reaction and the photo-initiated polymerization reaction. The composite membrane is then left to stand in ultrapure water and dried at room temperature to obtain a high-performance nanofiltration membrane with photo-initiated polymerization-assisted interfacial polymerization.

2. The method for preparing a high-performance nanofiltration membrane by photoinitiated polymerization-assisted interfacial polymerization according to claim 1, characterized in that, In step S1, the concentration of the acyl chloride monomer in the interfacial polymerization organic phase reaction is 0.1-1 wt%; the nonpolar organic solvent includes one or more of n-pentane, n-hexane, cyclohexane, n-heptane, and n-octane.

3. The method for preparing a high-performance nanofiltration membrane by photoinitiated polymerization-assisted interfacial polymerization according to claim 1, characterized in that, In step S2, the photoinitiator includes aromatic alkyl ketones or aromatic ketones, wherein the aromatic alkyl ketones include one or more of benzoin, benzoyl, acetophenone and its derivatives, α-hydroxy ketones, α-amino ketones and acylphosphine oxides; and the aromatic ketones include one or more of benzophenone, thioxanthone, anthraquinone, coumarin and camphorquinone.

4. The method for preparing a high-performance nanofiltration membrane by photoinitiated polymerization-assisted interfacial polymerization according to claim 3, characterized in that, In step S2, the co-initiator is a tertiary amine compound containing active hydrogen, including one or more of aliphatic tertiary amines, tertiary amine benzoates, ethanolamine tertiary amines, and active amines.

5. The method for preparing a high-performance nanofiltration membrane by photoinitiated polymerization-assisted interfacial polymerization according to claim 1, characterized in that, In step S2, the functional monomer crosslinking agent includes one or more of the following: 2-acrylamido-2-methyl-1-propanesulfonic acid, N,N-methylenebisacrylamide, 3-allyl-5,5-dimethylhydantoin, 2,2,3,4,4,4-hexafluorobutyl methacrylate, acrylamide, 2-hydroxyethyl acrylate, [2-(methacryloyloxy)ethyl]trimethylammonium chloride, vinyl sulfonic acid, glycidyl methacrylate, and trimethylolpropane acrylate.

6. The method for preparing a high-performance nanofiltration membrane by photoinitiated polymerization-assisted interfacial polymerization according to claim 1, characterized in that, In step S2, the interfacial polymerization aqueous phase reaction diamine monomer includes one or more of N,N-diaminopiperazine, N-(2-aminoethyl)-piperazine, 3,5-diaminobenzoylpiperazine, 4-aminobenzoylpiperazine, and 3-aminobenzoylpiperazine.

7. The method for preparing a high-performance nanofiltration membrane by photoinitiated polymerization-assisted interfacial polymerization according to claim 1, characterized in that, In step S3, the ultraviolet light and / or visible light comes from a xenon lamp, and the irradiance is 75-600 mW / cm². 2 The irradiation time is 0.5-8 minutes.

8. The method for preparing a high-performance nanofiltration membrane by photoinitiated polymerization-assisted interfacial polymerization according to claim 1, characterized in that, In step S4, the heat treatment temperature includes 40-70℃, and the heat treatment time includes 5-10 minutes.

9. The method for preparing a high-performance nanofiltration membrane by photoinitiated polymerization-assisted interfacial polymerization according to claim 1, characterized in that, In step S4, the composite membrane is left to stand in ultrapure water for 0.5-2 minutes.

10. The method for preparing a high-performance nanofiltration membrane by photoinitiated polymerization-assisted interfacial polymerization according to claim 1, characterized in that, In step S1, the base film includes one or more of polysulfone, polyethersulfone, polyvinylidene fluoride, or polyvinyl chloride, and the molecular weight cutoff of the base film is 50kDa-150kDa.

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