Polyamide nanocomposite membranes having high charge distribution channels and methods of making the same

Abstract

The application belongs to the technical field of mixed matrix membrane separation material preparation, and discloses a polyamide nanocomposite membrane with high charge distribution channels and a preparation method thereof. The composite membrane is composed of an ultrafiltration base film and a charged nanometer porous metal organic framework hybrid polyamide dense layer, and the charged nanometer porous metal organic framework hybrid polyamide dense layer is formed by interfacial polymerization of a mixed solution of water phase amine and UIO-66-NH2 base derivative and an organic acyl chloride solution on the surface of the ultrafiltration base film. The UIO-66-NH2 nanoparticles are modified by ionization to different degrees, and the modified UIO-66-NH2 nanoparticles can be uniformly dispersed between polyamide polymer segments, coordinate the microstructure and charge of the formed polyamide dense layer, and provide additional water molecule transmission channels.

Description

Technical Field

[0001] This invention belongs to the field of mixed matrix membrane separation material preparation technology, and particularly relates to polyamide nanocomposite membranes with high charge distribution channels and their preparation methods. Background Technology

[0002] To achieve the goals of "carbon peaking and carbon neutrality," and addressing the significant needs of energy conservation, emission reduction, and the transformation and upgrading of traditional industries, advancements in ion separation technology are crucial for the sustainable development of chemical industrial processes such as energy conversion and storage, environmental pollution and detection, clean industrial production, and resource recycling. Nanofiltration separation technology, with polyamide composite membranes at its core, combines excellent selectivity for monovalent / multivalent ions with low energy consumption, making it suitable for applications in chemical processes such as lithium extraction from salt lakes, brine refining (chlor-alkali industry), high-salinity wastewater resource recovery, waste acid (alkali) recovery, flow batteries, and salinity gradient power generation. However, existing polyamide nanomembranes exhibit a wide pore size distribution and strong surface electronegativity, limiting their effectiveness for ions with similar physicochemical parameters (such as Cl-). - SO4 2- Li + / Mg 2+ The separation accuracy of ion separation is relatively low, and its permeability needs to be further improved to reduce process energy consumption and investment costs. Therefore, given the huge demand for ion separation technology in the water, resources, and energy sectors, it is essential to develop membrane materials for fine ion sieving.

[0003] Current research generally suggests that the ion sieving performance of polyamide nanomembranes is primarily controlled by the synergistic effects of size sieving, charge repulsion, and dielectric repulsion. The stacked pores (aggregated pores) and network pores formed by polyamide polymer segments provide physical size selectivity, and these two pore structures are closely related to the molecular structure of the interfacial polymerization monomers and the interfacial polymerization process. Therefore, by designing novel reactive monomer structures at the molecular level or controlling the interfacial polymerization process, the pore size distribution of the polyamide separation layer can be narrowed, enhancing the size sieving effect and thus improving the ion sieving accuracy of polyamide nanofiltration membranes. For example, patent CN108452689A describes the design of a smaller and more flexible alicyclic acyl chloride monomer than the traditional trimesoyl chloride monomer to prepare a fully aliphatic polyamide nanofiltration membrane with a smaller average pore size. Its NaCl rejection rate remains below 16%, while its Na2SO4 rejection rate remains above 99.5%, exhibiting excellent Cl- filtration performance. - SO4 2-Selectivity. However, the increased density of the structure inevitably leads to a limited increase in permeation flux. Methods such as constructing an intermediate layer, controlling the diffusion rate of aqueous monomers, and controlling the interfacial distribution of aqueous monomers have been studied to improve the spatial order of the interfacial polymerization reaction, thereby narrowing the pore size distribution of the separation layer. For example, patents CN113262642A and CN112755817A utilize surfactants (such as sodium dodecyl sulfonate and phosphate diesters) to self-assemble a monomolecular network layer at the water-oil interface, thereby controlling the ordered diffusion of amine monomers to prepare a polyamide nanofiltration membrane with a uniform structure. These polyamide nanofiltration membranes with narrower pore size distributions all have a divalent cation rejection rate greater than 98.5%, a monovalent cation rejection rate less than 35%, and a water flux that can be maintained at 16 Lm. -2 h -1 bar -1 That's all. However, the stability and anti-fouling properties of these wrinkled and ultra-thin separation layers face challenges in practical long-term applications.

[0004] The surface of polyamide separation layers typically contains a large number of ionizable charged groups (such as -COOH and -NH2). These charged groups can interact electrostatically with ions, resulting in charge repulsion. Therefore, enhancing charge repulsion is another effective strategy to improve the ion selectivity of polyamide nanofiltration membranes. This can be achieved by screening aqueous / oil phase monomers to introduce more charged groups into the separation layer, increasing the membrane's charge density; or by surface modification (such as chemical grafting, chemical crosslinking, secondary interfacial polymerization, free radical reactions, etc.) to construct molecules with charged groups on the polyamide separation layer surface to increase the positive charge density of the membrane surface. For example, patent CN113694740A uses ionized quaternary ammonium salts as aqueous phase monomers to prepare polyamide membranes with high positive charge density inside the separation layer through interfacial polymerization. Compared with traditional PIP monomers, the diffusion rate and reactivity of these polyamine monomers affect the permeability of the final polyamide separation layer. Patent CN112844046A describes grafting multifunctional amine compounds (such as polyethyleneimine, polyethyleneamine, and polyacrylamide) onto the surface of the primary layer of a polyamide membrane via a secondary interfacial polymerization reaction to increase the charge density of the separation layer surface. While this surface modification method introduces an additional charged layer that significantly improves ion selectivity, it also increases film thickness and crosslinking density, leading to a sacrifice in permeability.

[0005] While numerous studies have focused on the advantages of nanoporous fillers with inherent pore sizes in overcoming the permeability-selectivity issues of polyamide membranes, research on designing charged nanoporous fillers and combining their synergistic effects of pore size sieving and charge repulsion to prepare polyamide nanocomposite membranes with highly charge-distributed pores for fine ion sieving has not been reported. Furthermore, improving the dispersibility and compatibility of nanoporous fillers within polyamide polymer segments remains a key challenge in the preparation of defect-free polyamide nanocomposite membranes. Summary of the Invention

[0006] To overcome the problems existing in related technologies, the present invention discloses embodiments of a polyamide nanocomposite membrane with high charge distribution channels and its preparation method, specifically designing charged nanoporous metal-organic frameworks (MOFs) for in-situ preparation of defect-free, highly permeable, and highly ion-selective (Mg) nanocomposite membranes. 2+ / Li + SO4 2- / Cl - Metal-organic framework-based hybrid matrix membranes.

[0007] The technical solution is as follows: A polyamide nanocomposite membrane with high charge distribution channels is composed of an ultrafiltration base membrane and a dense polyamide layer hybridized with charged nanoporous metal-organic frameworks (MOFs). The molecular structure of the polyamide nanocomposite membrane with high charge distribution channels is as follows:

[0008]

[0009] In one embodiment, the charged nanoporous metal-organic framework (MOF) hybrid polyamide dense layer is formed by the polymerization of an aqueous amine solution and an oil-phase organic acyl chloride solution at the surface interface of an ultrafiltration membrane.

[0010] In one embodiment, the ultrafiltration membrane includes a porous support layer, which is a polysulfone ultrafiltration membrane, a polyethersulfone ultrafiltration membrane, or a polyacrylonitrile ultrafiltration membrane prepared by phase inversion on the surface of a nonwoven fabric; the aqueous amine solution is a mixed solution of an organic amine and a high charge density UIO-66-NH2-based derivative.

[0011] The porous support layer was successively immersed in an aqueous amine solution and an oil-phase organic acyl chloride solution, and then polymerized at the interface to form a dense polyamide layer hybridized with charged nanoporous metal-organic frameworks (MOFs).

[0012] In one embodiment, the charged UIO-66-NH2-based derivative is at least one of the UIO-66-NH2-based derivatives modified with quaternary ammonium, imidazole, or sulfonic acid groups; the modifying agent required to prepare the UIO-66-NH2-based derivatives modified with quaternary ammonium, imidazole, or sulfonic acid groups is at least one of 1,3-propylsulfonate lactone, 1,4-butanesulfonate lactone, 2,3-glycidyltrimethylammonium chloride, glycidyltriethylammonium chloride, dodecyldimethylglycidylammonium chloride, 3-chloro-2-hydroxypropyltriethylammonium chloride, O-methacryloyl-oxyethyldimethylglycidylammonium chloride, 4-imidazolium formaldehyde, and 2-imidazolium formaldehyde.

[0013] In one embodiment, the organic amine monomer in the aqueous amine solution is two or more -NH- or -NH2- attached to an alicyclic saturated hydrocarbon or replacing the original aliphatic or aromatic C; the organic amine monomer is one or more of piperazine, tris(2-aminoethyl)amine, m-phenylenediamine, polyethyleneimine, 2,5-dimethylpiperazine, (1R,2R)-(-)-1,2-cyclohexanediamine, 1,2-cyclohexanediamine, 2,6-dimethylpiperazine, and 1,4-cyclohexanediamine; the organic solvent for preparing the aqueous amine solution is at least one of cyclohexane, n-hexane, n-heptane, ISOPAR-G, ISOPAR-E, and ISOPAR-H.

[0014] In one embodiment, the organic acyl chloride monomer in the oil phase organic acyl chloride solution consists of three or more -COCl groups attached to a saturated hydrocarbon or aromatic hydrocarbon, and the organic acyl chloride monomer is one or more of the following: trimesoyl chloride, 1,2,3,4-cyclobutanetetracarboxylate chloride, 1,2,4,5-cyclohexanetetracarboxylate chloride, 1,3,5-cyclohexanetricarboxylate chloride, and 1,2,3,4-cyclopentanetetracarboxylate chloride.

[0015] Another objective of this invention is to provide a method for preparing a polyamide nanocomposite membrane with highly charged pores. This method involves designing UIO-66-NH2 nanoporous fillers modified with different charged groups through a post-modification strategy. The soluble charged nanoporous fillers are uniformly dispersed between polyamide polymer segments, coordinating the microstructure and charge of the polyamide separation layer. The method specifically includes the following steps:

[0016] S1, Dissolve organic amine in water to prepare an organic amine solution with a mass concentration of 0.05%-4wt%, then add 0.005%-2wt% of high charge density UIO-66-NH2 derivative, 0-2.3wt% of triethylamine and 0-4.6wt% of camphor sulfonic acid to the organic amine solution, stir thoroughly, and then disperse by ultrasonication to obtain an aqueous solution;

[0017] S2, Immerse the ultrafiltration membrane in the aqueous solution from step S1 for 1-10 minutes, then remove it and use an air knife or rubber roller to dry the residual aqueous solution on the surface of the ultrafiltration membrane.

[0018] S3, prepare an organic acyl chloride solution using 0.01-0.4 wt% polyacyl chloride, 0-1 wt% tributyl phosphate and 0-1 wt% acetone, immerse the upper surface of the membrane obtained in step S2 in the organic acyl chloride solution, and carry out interfacial polymerization reaction for 10-100s to form a polyamide separation layer. After the reaction is completed, discard the remaining organic acyl chloride solution.

[0019] S4. Place the membrane obtained in step S3 in an oven at 60-100℃ for thermal crosslinking for 1-10 minutes, and then remove it to obtain a polyamide nanocomposite membrane with high charge distribution channels.

[0020] In one embodiment, in step S1, the preparation of the high charge density UIO-66-NH2-based derivative includes: adding an appropriate amount of UIO-66-NH2 to methanol, stirring and sonicating, then adding sulfonate lactones, epoxy quaternary ammonium salts or imidazole aldehydes as small molecules, reacting at 40-80°C for 4-12 hours, and then centrifuging, washing and freeze-drying the product to obtain the charged UIO-66-NH2-based derivative;

[0021] The structure of the charged UIO-66-NH2-based derivative is as follows:

[0022]

[0023] In one embodiment, in the preparation of the charged UIO-66-NH2-based derivative, the sulfonate lactone small molecule is one of 1,3-propylsulfonate lactone and 1,4-butanesulfonate lactone.

[0024] The epoxy quaternary ammonium salt small molecule is one of 2,3-epoxypropyltrimethylammonium chloride, epioxypropyltriethylammonium chloride, dodecyl dimethylepoxypropylammonium chloride, 3-chloro-2-hydroxypropyltriethylammonium chloride, and O-methacryloyl-oxyethyl dimethylepoxypropylammonium chloride;

[0025] The imidazole aldehyde small molecule is one of 4-imidazolium carboxaldehyde and 2-imidazolium carboxaldehyde.

[0026] Combining all the above technical solutions, the advantages and positive effects of this invention are as follows:

[0027] This invention discloses a polyamide nanocomposite membrane with high charge distribution channels and its preparation method. The composite membrane of this invention is composed of an ultrafiltration base membrane and a dense polyamide layer hybridized with charged nanoporous metal-organic frameworks (MOFs). The dense polyamide layer hybridized with charged nanoporous metal-organic frameworks (MOFs) is formed by interfacial polymerization of an aqueous amine and a high charge density UIO-66-NH2-based derivative solution and an organic acyl chloride solution on the surface of the ultrafiltration base membrane. The charged UIO-66-NH2-based derivative is a UIO-66-NH2-based derivative modified with quaternary ammonium, imidazole, or sulfonic acid groups. This invention designs UIO-66-NH2-based derivatives modified with quaternary ammonium, imidazole, and sulfonic acid groups through a post-modification strategy. Soluble charged nanoporous fillers can be uniformly dispersed between polyamide polymer segments, coordinating the microstructure and charge of the formed dense polyamide layer to prepare a polyamide nanocomposite membrane with high charge distribution channels. The composite membrane prepared by this invention has high ion selectivity and permeability, and can be applied to chemical fields such as lithium extraction from salt lakes, brine refining (chlor-alkali industry), resource utilization of high-salinity wastewater, waste acid (alkali) recovery, flow batteries and salinity gradient power generation.

[0028] This invention provides a method for in-situ preparation of polyamide nanocomposite membranes with high charge distribution pores by designing charged nanoporous fillers (high charge density UIO-66-NH2-based derivatives) with controllable charge density. This invention designs UIO-66-NH2 nanoporous fillers modified with different charged groups through a post-modification strategy. The soluble charged nanoporous fillers can be uniformly dispersed between polyamide polymer chains, coordinating the microstructure and charge of the formed polyamide separation layer. This method utilizes the abundant charged groups and inherent pore size advantages of nanoporous organic frameworks to control the charge density and pore size distribution of the polyamide separation layer. Furthermore, this method combines the abundant charged groups, pore regularity, and ion size sieving properties of MOFs with the advantages of a soft and processable polymer matrix, theoretically greatly improving the ion selectivity and permeability of traditional polymer nanomembranes.

[0029] This invention utilizes the -NH2 groups in the UIO-66-NH2 organic framework structure to modify it to varying degrees at the molecular scale through a post-modification strategy. Quaternary ammonium, imidazole, or sulfonic acid groups are introduced into the UIO-66-NH2 framework structure to improve its dispersibility and solubility in aqueous amine solutions, ultimately forming a stable colloidal solution. During interfacial polymerization, the modified UIO-66-NH2 nanofiller not only affects the distribution and diffusion of the aqueous amine monomer on the substrate surface but also occupies interfacial reaction sites, causing polyamide polymer segments to form around the three-dimensional nano-UIO-66-NH2 framework structure, increasing the formation of polyamide segment stacking pores. Furthermore, the ordered channels and charged groups in the charged nano-UIO-66-NH2 framework structure ultimately increase the orderliness and charge of the polyamide nanofilm's pores. Therefore, the prepared polyamide nanocomposite membrane with highly charged pores exhibits increased pore orderliness, charge density, and porosity, leading to a significant enhancement in ion sieving performance.

[0030] This invention prepares UIO-66-NH2 nanoparticles with surfaces rich in quaternary ammonium, imidazole, or sulfonic acid ion groups by subjecting the surface of UIO-66-NH2 nanoparticles to different degrees of ionization modification, thus creating charged nanoporous fillers. The modified UIO-66-NH2 nanoparticles not only disperse stably and uniformly in aqueous solutions, but also, through interfacial polymerization, can stably exist within polyamide polymer segments, increasing the charge density of the polyamide dense layer. Furthermore, as porous materials, they significantly improve water flux.

[0031] When the mixed matrix membrane prepared according to this invention was tested under simulated drinking water conditions (2000 ppm NaCl / Na2SO4 / MgCl2 / LiCl 145 psi), the high positive charge density UIO-66-NH2 nanoparticle hybrid polyamide nanocomposite membrane exhibited a MgCl2 rejection rate of 96.2-98.5%, a LiCl rejection rate of 18.8-40.1%, and a water flux of 229.1-386.3 L·m -2 ·h -1 The prepared polyamide nanocomposite membranes with high negative charge density UIO-66-NH2 nanoparticle hybrids exhibited a Na2SO4 rejection rate of 96.5%-99.3%, a NaCl rejection rate of 16.3%-39.5%, and a water flux of 302.8-420.6 L·m⁻¹. -2 ·h -1 Permeation flux and ion selectivity (Mg) 2+ / Li + SO4 2- / Cl - The selectivity is superior to that of currently reported ion-selective composite membranes, indicating that the membrane preparation method of the present invention represents a significant technological advancement.

[0032] The sulfonyl lactones, aldehyde imidazoles, and epoxy quaternary ammonium salts used in this invention have advantages such as simple structure, low cost, and easy availability. Furthermore, the modification method is simple and easy to promote in industrial applications. The UIO-66-NH2 nanoparticles modified by this invention not only disperse uniformly between polyamide polymer chains, coordinating the microstructure and charge of the formed dense polyamide layer, but also provide additional water molecule transport channels due to their inherent nanopores. Attached Figure Description

[0033] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure;

[0034] Figure 1 This is a flowchart of the preparation method of a polyamide nanocomposite film with high charge distribution channels provided in the embodiments of the present invention;

[0035] Figure 2 This is a surface morphology image of a polyamide nanocomposite film with high charge distribution channels prepared according to an embodiment of the present invention;

[0036] Figure 3 This is a morphology diagram of the quaternary ammonium group-modified UIO-66-NH2 nanoparticles designed and synthesized in Example 3 of this invention.

[0037] Figure 4This is a schematic diagram of the charge density of the composite films prepared in Comparative Examples 1, 4 and 11 provided in the embodiments of the present invention. Detailed Implementation

[0038] 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. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0039] Example 1: The polyamide nanocomposite membrane with high charge distribution channels provided in this embodiment of the invention is composed of an ultrafiltration base membrane and a high charge density nanoporous metal-organic framework (MOF) hybridized polyamide dense layer. The charged nanoporous metal-organic framework (MOF) hybridized polyamide dense layer is formed by the polymerization of an aqueous amine mixture and an oil-phase organic acyl chloride solution at the surface interface of the ultrafiltration base membrane. The aqueous amine mixture is a mixture of an organic amine and a high charge density UIO-66-NH2-based derivative. The high charge density UIO-66-NH2-based derivative is at least one of quaternary ammonium, imidazole, or sulfonic acid-modified UIO-66-NH2-based derivatives.

[0040] In this embodiment of the invention, the organic amine is at least one of m-phenylenediamine, piperazine, polyethyleneimine, tris(2-aminoethyl)amine, 2,5-dimethylpiperazine, (1R,2R)-(-)-1,2-cyclohexanediamine, 1,2-cyclohexanediamine, 2,6-dimethylpiperazine, and 1,4-cyclohexanediamine.

[0041] In this embodiment of the invention, the modifying reagent required for preparing the UIO-66-NH2 derivative modified with quaternary ammonium, imidazole, or sulfonic acid groups is at least one of 1,3-propylsulfonate lactone, 1,4-butanesulfonate lactone, 2,3-epoxypropyltrimethylammonium chloride, epioxypropyltriethylammonium chloride, dodecyl dimethyl epioxypropylammonium chloride, 3-chloro-2-hydroxypropyltriethylammonium chloride, O-methacryloyl-oxyethyldimethylepoxypropylammonium chloride, 4-imidazolium formaldehyde, and 2-imidazolium formaldehyde.

[0042] In this embodiment of the invention, the organic acyl chloride is at least one selected from pyromellitic acid tricarboxylate chloride, 1,2,3,4-cyclobutanetetracarboxylate chloride, 1,2,4,5-cyclohexanetetracarboxylate chloride, 1,3,5-cyclohexanetricarboxylate chloride, and 1,2,3,4-cyclopentanetetracarboxylate chloride. The organic solvent is at least one selected from cyclohexane, n-hexane, n-heptane, ISOPAR-G, ISOPAR-E, and ISOPAR-H.

[0043] In this embodiment of the invention, the ultrafiltration base membrane includes a polysulfone ultrafiltration membrane, a polyethersulfone ultrafiltration membrane, or a polyacrylonitrile ultrafiltration membrane.

[0044] like Figure 1 As shown, the method for preparing a polyamide nanocomposite film with high charge distribution channels provided in this embodiment of the invention includes the following steps:

[0045] S1, Dissolve organic amine in water to prepare an organic amine solution with a mass concentration of 0.05%-4wt%, then add 0.005%-2wt% of high charge density UIO-66-NH2 derivative, 0-2.3wt% of triethylamine and 0-4.6wt% of camphor sulfonic acid to the organic amine solution, stir thoroughly, and then disperse by ultrasonication to obtain an aqueous solution;

[0046] S2, Immerse the ultrafiltration membrane in the aqueous solution from step S1 for 1-10 minutes, then remove it and use an air knife or rubber roller to dry the residual aqueous solution on the surface of the ultrafiltration membrane.

[0047] S3, prepare an organic acyl chloride solution using 0.01-0.4 wt% polyacyl chloride, 0-1 wt% tributyl phosphate and 0-1 wt% acetone, immerse the upper surface of the membrane obtained in step S2 in the organic acyl chloride solution, and carry out interfacial polymerization reaction for 10-100s to form a polyamide separation layer. After the reaction is completed, discard the remaining organic acyl chloride solution.

[0048] S4, After thermally crosslinking the membrane obtained in step S3 in an oven at 60-100℃ for 1-10 min, remove it to obtain a polyamide nanocomposite membrane with highly charged pores. Figure 2 This is a surface morphology image of the polyamide nanocomposite film with high charge distribution channels prepared according to an embodiment of the present invention.

[0049] Example 2: The polyamide nanocomposite membrane with high charge distribution channels provided in this embodiment of the invention has the following structural formula:

[0050]

[0051] Where R is a molecule with a charged group.

[0052] The polyamide nanocomposite membrane with high charge distribution channels is composed of nonwoven fabric, a porous support layer, and a polyamide nanodense layer containing a charged UIO-66-NH2 framework structure. The porous support layer is a polysulfone ultrafiltration membrane prepared by phase inversion on the surface of the nonwoven fabric. The polyamide dense layer containing UIO-66-NH2 derivatives is formed by interfacial polymerization of the porous support layer after being impregnated in an aqueous amine solution and an oil-phase organic acyl chloride solution. The aqueous amine solution contains UIO-66-NH2 derivatives with high charge density.

[0053] The organic amine monomer in the aqueous amine solution consists of two or more "-NH-, -NH2" groups attached to an alicyclic saturated hydrocarbon or replacing the original alicyclic or aromatic C groups. Further, the organic amine monomers that can be selected in this invention are one or more of piperazine, tris(2-aminoethyl)amine, m-phenylenediamine, polyethyleneimine, 2,5-dimethylpiperazine, (1R,2R)-(-)-1,2-cyclohexanediamine, 1,2-cyclohexanediamine, 2,6-dimethylpiperazine, and 1,4-cyclohexanediamine.

[0054] The acyl chloride monomer in the oil phase organic acyl chloride solution has three or more "-COCl" groups attached to a saturated hydrocarbon or aromatic hydrocarbon. Further, the acyl chloride monomers that can be selected in this invention are one or more of the following: trimesoyl chloride, 1,2,3,4-cyclobutanetetracarboxylate chloride, 1,2,4,5-cyclohexanetetracarboxylate chloride, 1,3,5-cyclohexanetricarboxylate chloride, and 1,2,3,4-cyclopentanetetracarboxylate chloride.

[0055] In this embodiment of the invention, a method for preparing a polyamide nanocomposite film with high charge distribution channels is provided, comprising the following steps:

[0056] (1) Preparation of aqueous solution: Dissolve UIO-66-NH2 derivative and polyamine in pure water, and then add triethylamine and camphor sulfonic acid as additives; generally speaking, the mass concentration of UIO-66-NH2 derivative and polyamine is 0.005-2wt% and 0.05-4wt%, respectively, and the mass concentration of triethylamine and camphor sulfonic acid is 0-2.3wt% and 0-4.6wt%, respectively.

[0057] (2) Preparation of the oil phase solution: Dissolve polyacryl chloride in an organic solvent, and then add tributyl phosphate and acetone as additives. Generally speaking, the mass concentrations of polyacryl chloride, tributyl phosphate and acetone are 0.01-0.4wt%, 0-1wt%, and 0-1wt%, respectively; the solvent of the oil phase monomer is one or more of cyclohexane, n-hexane, n-heptane, ISOPAR-G, ISOPAR-E and ISOPAR-H.

[0058] (3) Preparation of high-performance polyamide nanocomposite membrane: The ultrafiltration porous support layer is soaked in 1% sodium hydroxide or 1.5% NaHCO3 aqueous solution for 30 min, washed with ultrapure water and dried. The ultrafiltration porous support layer is then immersed in the above aqueous amine solution for 1-10 min, the surface water droplets are removed, and it is immersed in polyacrylamide chloride solution for 10-100 s to form a dense polyamide layer. It is then taken out and placed in a vacuum drying oven for heat treatment at 60-100℃ for 1-10 min. Preferably, the pore size of the porous support layer is 10-40 nm.

[0059] In this embodiment of the invention, the preparation method of UIO-66-NH2 nanoparticles is as follows: A solution was prepared according to the molar ratio of ZrCl4:2-aminoterephthalic acid:water:N,N-dimethylformamide (DMF) of 1:1:162:741. After stirring and ultrasonic treatment, the solution was poured into a reaction vessel and heated at 120°C for 24 hours. After centrifugation at 10000 rpm for 30 minutes, the sediment was collected, washed three times with methanol, and then washed three times with water. Finally, UIO-66-NH2 nanoparticles with a particle size of approximately 30-50 nm were obtained.

[0060] The preparation method of charged UIO-66-NH2 derivative is as follows: Add an appropriate amount of UIO-66-NH2 to methanol, stir and sonicate, then add sulfonyl lactones, epoxy quaternary ammonium salts or imidazole aldehydes. After reacting at 40-80℃ for 4-12 hours, the product is centrifuged, washed and freeze-dried to obtain the charged UIO-66-NH2 derivative.

[0061] The structural formula of the charged UIO-66-NH2-based derivative is as follows:

[0062]

[0063] The sulfonyl lactone small molecule is one of 1,3-propylsulfonyl lactone and 1,4-butanesulfonyl lactone.

[0064] The epoxy quaternary ammonium salt small molecule is one of the following: 2,3-epoxypropyltrimethylammonium chloride, epioxypropyltriethylammonium chloride, dodecyl dimethylepoxypropylammonium chloride, 3-chloro-2-hydroxypropyltriethylammonium chloride, and O-methacryloyl-oxyethyldimethylepoxypropylammonium chloride.

[0065] The imidazole aldehyde small molecule is one of 4-imidazolium carboxaldehyde and 2-imidazolium carboxaldehyde.

[0066] Comparative Example 1, the existing method for preparing a mixed matrix composite membrane includes the following steps: (1) Preparation of aqueous solution: prepare an aqueous solution of 0.02 w / v% UIO-66-NH2 and 1.0 w / v% PIP;

[0067] (2) Preparation of oil phase solution: Prepare a 0.1 w / v % hexane solution of pyromellitic chloride;

[0068] (3) Preparation of polyamide nanocomposite membrane: Soak the polysulfone ultrafiltration membrane in ultrapure water, wash it, blow it dry, immerse it in the aqueous solution of step (1) for 2 minutes, remove the surface water droplets, immerse it in the acyl chloride solution of step (2), and after 30 seconds, a dense polyamide layer is formed. Then, place it at 60℃ for heat treatment for 5 minutes.

[0069] Using 2000ppm MgCl2 and LiCl aqueous solution as test solutions, the prepared mixed matrix composite membrane was continuously filtered for 1h under an operating pressure of 145psi. The performance of the composite membrane was tested, and the results are shown in Table 1.

[0070] Comparative Example 2, the existing method for preparing a hybrid matrix composite membrane includes the following steps:

[0071] (1) Preparation of aqueous solution: Prepare aqueous solutions of 0.02 w / v% UIO-66-NH2 and 0.8 w / v% PIP;

[0072] (2) Preparation of oil phase solution: Prepare a cyclohexane solution of 0.1 w / v% 1,2,3,4-cyclopentanetetrachlorochloride and 1 w / v% acetone;

[0073] (3) Preparation of polyamide nanocomposite membrane: Soak the polysulfone ultrafiltration membrane in ultrapure water, wash it, blow it dry, immerse it in the aqueous solution of step (1) for 2 min, remove the surface water droplets, immerse it in the acyl chloride solution of step (2), and after 20 s, a dense polyamide layer is formed. Then, place it at 60℃ for heat treatment for 5 min.

[0074] Using 2000ppm Na2SO4 and NaCl aqueous solutions as test solutions, the prepared mixed matrix composite membrane was continuously filtered for 1 hour at an operating pressure of 145psi. The performance of the composite membrane was tested, and the results are shown in Table 1.

[0075] Example 3, this embodiment of the invention provides a method for preparing a polyamide nanocomposite film with high charge distribution channels, comprising the following steps:

[0076] Preparation of UIO-66-NH2 nanoparticles rich in quaternary ammonium groups: 1.414 g of UIO-66-NH2 (Mw = 2828.95) was ultrasonically dispersed in 60 ml of methanol solution. Under stirring, 0.67 g of 2,3-epoxypropyltrimethylammonium chloride was added dropwise. The reaction was carried out at 50 °C for 6 hours. The product was washed with methanol, centrifuged, and freeze-dried to obtain the 2,3-epoxypropyltrimethylammonium chloride-modified UIO-66-NH2 derivative. Figure 3 The structure is as follows:

[0077]

[0078] (1) Preparation of aqueous solution: Prepare 0.02 w / v% 2,3-epoxypropyltrimethylammonium chloride modified UIO-66-NH2 derivative and 1.0 w / v% piperazine aqueous solution;

[0079] (2) Preparation of oil phase solution: Prepare a 0.1 w / v % hexane solution of pyromellitic chloride;

[0080] (3) Preparation of high-performance polyamide nanocomposite membrane: Soak the polysulfone ultrafiltration membrane in ultrapure water, wash it, blow it dry, immerse it in the aqueous solution of step (1) for 2 min, remove the surface water droplets, immerse it in the 0.1 w / v% trimesoyl chloride n-hexane solution of step (2), after 30 s, a dense polyamide layer is formed, and then place it at 60 ℃ for heat treatment for 5 min.

[0081] Using 2000ppm MgCl2 and LiCl aqueous solution as test solutions, the prepared polyamide nanocomposite membrane with high charge distribution channels was continuously filtered for 1h under an operating pressure of 145psi. The performance of the composite membrane was tested, and the results are shown in Table 1.

[0082] Example 4, this embodiment of the invention provides a method for preparing a polyamide nanocomposite film with high charge distribution channels, comprising the following steps:

[0083] (1) Preparation of aqueous solution: Prepare 0.1 w / v% 2,3-epoxypropyltrimethylammonium chloride modified UIO-66-NH2 derivative (same as in Example 3) and 1.0 w / v% piperazine aqueous solution;

[0084] (2) Preparation of oil phase solution: Prepare a 0.1 w / v % hexane solution of pyromellitic chloride;

[0085] (3) Preparation of high-performance polyamide nanocomposite membrane: Soak the polysulfone ultrafiltration membrane in ultrapure water, wash it, blow it dry, immerse it in the aqueous solution of step (1) for 2 min, remove the surface water droplets, immerse it in the acyl chloride solution of step (2), and after 30 s, a dense polyamide layer is formed. Then, place it at 60℃ for heat treatment for 5 min.

[0086] Using 2000ppm MgCl2 and LiCl aqueous solution as test solutions, the prepared mixed matrix composite membrane was continuously filtered for 1h under an operating pressure of 145psi. The performance of the composite membrane was tested, and the results are shown in Table 1.

[0087] Example 5, this embodiment of the invention provides a method for preparing a polyamide nanocomposite film with high charge distribution channels, comprising the following steps:

[0088] (1) Preparation of aqueous solution: Prepare an aqueous solution of 0.08 w / v ethylene-2,3-epoxypropyltrimethylammonium chloride modified UIO-66-NH2 derivative (same as in Example 3) and 1.0 w / v hyperbranched polyethyleneimine (PEI-70000);

[0089] (2) Preparation of oil phase solution: Prepare a 0.1 w / v % hexane solution of pyromellitic methyl chloride;

[0090] (3) Preparation of high-performance polyamide nanocomposite membrane: Soak the polysulfone ultrafiltration membrane in ultrapure water, wash it, blow it dry, immerse it in the aqueous solution of step (1) for 2 min, remove the surface water droplets, immerse it in the acyl chloride solution of step (2), and after 30 s, a dense polyamide layer is formed. Then, place it at 60℃ for heat treatment for 5 min.

[0091] Using 2000ppm MgCl2 and LiCl aqueous solution as test solutions, the prepared polyamide nanocomposite membrane with high charge distribution channels was continuously filtered for 1h under an operating pressure of 145psi. The performance of the composite membrane was tested, and the results are shown in Table 1.

[0092] Example 6, this embodiment of the invention provides a method for preparing a polyamide nanocomposite film with high charge distribution channels, comprising the following steps:

[0093] (1) Preparation of aqueous solution: Prepare an aqueous solution of 0.08 w / v ethylene-2,3-epoxypropyltrimethylammonium chloride modified UIO-66-NH2 derivative (same as in Example 3) and 1.0 w / v tris(2-aminoethyl)amine;

[0094] (2) Preparation of oil phase solution: Prepare a 0.1 w / v % hexane solution of pyromellitic chloride;

[0095] (3) Preparation of high-performance polyamide nanocomposite membrane: Soak the polysulfone ultrafiltration membrane in ultrapure water, wash it, blow it dry, immerse it in the aqueous solution of step (1) for 2 min, remove the surface water droplets, immerse it in the acyl chloride solution of step (2), and after 30 s, a dense polyamide layer is formed. Then, place it at 60℃ for heat treatment for 5 min.

[0096] Using 2000ppm MgCl2 and LiCl aqueous solution as test solutions, the prepared polyamide nanocomposite membrane with high charge distribution channels was continuously filtered for 1h under an operating pressure of 145psi. The performance of the composite membrane was tested, and the results are shown in Table 1.

[0097] Example 7, this embodiment of the invention provides a method for preparing a polyamide nanocomposite film with high charge distribution channels, comprising the following steps:

[0098] Preparation of UIO-66-NH2 nanoparticles with surface rich in imidazole groups: 1.414 g of UIO-66-NH2 (Mw = 2828.95) was ultrasonically dispersed in 30 ml of methanol solution. 0.38 g of 2-imidazolium formaldehyde was added dropwise under stirring. The reaction was carried out at 50 °C for 6 hours. The solvent was then removed, the mixture was neutralized with HCl, and after washing, centrifugation, and freeze-drying, the product was obtained with the following structure:

[0099]

[0100] (1) Preparation of aqueous solution: Prepare 0.02 w / v% imidazole-based UIO-66-NH2 derivative and 1.0 w / v% piperazine aqueous solution;

[0101] (2) Preparation of oil phase solution: Prepare a 0.1 w / v % hexane solution of pyromellitic chloride;

[0102] (3) Preparation of high-performance polyamide nanocomposite membrane: Soak the polysulfone ultrafiltration membrane in ultrapure water, wash it, blow it dry, immerse it in the aqueous solution of step (1) for 2 min, remove the surface water droplets, immerse it in the acyl chloride solution of step (2), and after 30 s, a dense polyamide layer is formed. Then, place it at 60℃ for heat treatment for 5 min.

[0103] Using 2000ppm MgCl2 and LiCl aqueous solution as test solutions, the prepared polyamide nanocomposite membrane with high charge distribution channels was continuously filtered for 1h under an operating pressure of 145psi. The performance of the composite membrane was tested, and the results are shown in Table 1.

[0104] Example 8, this embodiment of the invention provides a method for preparing a polyamide nanocomposite film with high charge distribution channels, comprising the following steps:

[0105] (1) Preparation of aqueous solution: Prepare 0.08 w / v% imidazole-based UIO-66-NH2 derivative (same as in Example 5) and 1.0 w / v% piperazine aqueous solution;

[0106] (2) Preparation of oil phase solution: Prepare a 0.1 w / v % hexane solution of pyromellitic chloride;

[0107] (3) Preparation of high-performance polyamide nanocomposite membrane: Soak the polysulfone ultrafiltration membrane in ultrapure water, wash it, blow it dry, immerse it in the aqueous solution of step (1) for 2 minutes, remove the surface water droplets, immerse it in the acyl chloride solution of step (2), and after 30 seconds, a dense polyamide layer is formed. Then, place it at 60℃ for heat treatment for 5 minutes.

[0108] Using 2000ppm MgCl2 and LiCl aqueous solution as test solutions, the prepared polyamide nanocomposite membrane with high charge distribution channels was continuously filtered for 1h under an operating pressure of 145psi. The performance of the composite membrane was tested, and the results are shown in Table 1.

[0109] Example 9, this embodiment of the invention provides a method for preparing a polyamide nanocomposite film with high charge distribution channels, comprising the following steps:

[0110] (1) Preparation of aqueous solution: Prepare an aqueous solution of 0.08 w / v% imidazole-based UIO-66-NH2 derivative (same as in Example 5) and 1.0 w / v% tris(2-aminoethyl)amine;

[0111] (2) Preparation of oil phase solution: Prepare a 0.1 w / v % hexane solution of pyromellitic chloride;

[0112] (3) Preparation of high-performance polyamide nanocomposite membrane: Soak the polysulfone ultrafiltration membrane in ultrapure water, wash it, blow it dry, immerse it in the aqueous solution of step (1) for 2 minutes, remove the surface water droplets, immerse it in the acyl chloride solution of step (2), and after 30 seconds, a dense polyamide layer is formed. Then, place it at 60℃ for heat treatment for 5 minutes.

[0113] Using 2000ppm MgCl2 and LiCl aqueous solution as test solutions, the prepared polyamide nanocomposite membrane with high charge distribution channels was continuously filtered for 1h under an operating pressure of 145psi. The performance of the composite membrane was tested, and the results are shown in Table 1.

[0114] Example 10: This embodiment of the invention provides a method for preparing a polyamide nanocomposite film with high charge distribution channels, comprising the following steps:

[0115] Preparation of UIO-66-NH2 nanoparticles with sulfonic acid groups on the surface: 1.0 g of UIO-66-NH2 (Mw = 2828.95) was ultrasonically dispersed in 30 ml of methanol solution. 0.54 g of 1,3-propylsulfonate lactone was added dropwise under stirring. The reaction was carried out at 50 °C for 12 hours. The product was washed with methanol, centrifuged, and freeze-dried to obtain the sulfonic acid group-modified UIO-66-NH2 derivative with the following structure:

[0116]

[0117] (1) Preparation of aqueous solution: Prepare 0.02 w / v% of 1,3-propylsulfonate lactone-modified UIO-66-NH2 derivative and 0.8 w / v% of piperazine aqueous solution;

[0118] (2) Preparation of oil phase solution: Prepare a 0.1 w / v % hexane solution of pyromellitic chloride;

[0119] (3) Preparation of high-performance polyamide nanocomposite membrane: Soak the polysulfone ultrafiltration membrane in ultrapure water, wash it, blow it dry, immerse it in the aqueous solution of step (1) for 2 min, remove the surface water droplets, immerse it in the acyl chloride solution of step (2), and after 20 s, a dense polyamide layer is formed. Then, place it at 60℃ for heat treatment for 2 min.

[0120] Using 2000ppm Na2SO4 and NaCl aqueous solutions as test solutions, the prepared polyamide nanocomposite membrane with high charge distribution channels was continuously filtered for 1h under an operating pressure of 145psi. The performance of the composite membrane was tested, and the results are shown in Table 1.

[0121] Example 11, this embodiment of the invention provides a method for preparing a polyamide nanocomposite film with high charge distribution channels, comprising the following steps:

[0122] (1) Preparation of aqueous solution: Prepare 0.08 w / v% of 1,3-propylsulfonate lactone modified UIO-66-NH2 derivative (same as in Example 10) and 0.8 w / v% of piperazine aqueous solution;

[0123] (2) Preparation of oil phase solution: Prepare a hexane solution containing 0.1 w / v% pyromellitic methyl chloride, 0.1 w / v% tributyl phosphate, and 1 w / v% acetone;

[0124] (3) Preparation of high-performance polyamide nanocomposite membrane: Soak the polysulfone ultrafiltration membrane in ultrapure water, wash it, blow it dry, immerse it in the aqueous solution of step (1) for 2 min, remove the surface water droplets, immerse it in the acyl chloride solution of step (2), and after 30 s, a dense polyamide layer is formed. Then, place it at 60℃ for heat treatment for 2 min.

[0125] Using 2000ppm Na2SO4 and NaCl aqueous solutions as test solutions, the prepared polyamide nanocomposite membrane with high charge distribution channels was continuously filtered for 1h under an operating pressure of 145psi. The performance of the composite membrane was tested, and the results are shown in Table 1.

[0126] Example 12, this embodiment of the invention provides a method for preparing a polyamide nanocomposite film with high charge distribution channels, comprising the following steps:

[0127] (1) Preparation of aqueous solution: Prepare an aqueous solution of 0.04 w / v% 1,3-propylsulfonate lactone modified UIO-66-NH2 derivative (same as in Example 10) and 1.0 w / v% piperazine;

[0128] (2) Preparation of oil phase solution: Prepare a cyclohexane solution of 0.1 w / v% 1,2,3,4-cyclopentanetetrachlorochloride and 1 w / v% acetone;

[0129] (3) Preparation of high-performance polyamide nanocomposite membrane: Soak the polysulfone ultrafiltration membrane in ultrapure water, wash it, blow it dry, immerse it in the aqueous solution of step (1) for 2 min, remove the surface water droplets, immerse it in the acyl chloride solution of step (2), and after 20 s, a dense polyamide layer is formed. Then, place it at 60℃ for heat treatment for 2 min.

[0130] Using 2000ppm Na2SO4 and NaCl aqueous solutions as test solutions, the prepared polyamide nanocomposite membrane with high charge distribution channels was continuously filtered for 1h under an operating pressure of 145psi. The performance of the composite membrane was tested, and the results are shown in Table 1.

[0131] Example 13, this embodiment of the invention provides a method for preparing a polyamide nanocomposite film with high charge distribution channels, comprising the following steps:

[0132] (1) Preparation of aqueous amine solution: Prepare an aqueous solution of 0.08 w / v% 1,3-propylsulfonate lactone modified UIO-66-NH2 derivative (same as in Example 10) and 1.0 w / v% piperazine;

[0133] (2) Preparation of oil phase solution: Prepare a cyclohexane solution of 0.1 w / v% 1,2,3,4-cyclopentanetetrachlorochloride and 1 w / v% acetone;

[0134] (3) Preparation of high-performance polyamide nanocomposite membrane: Soak the polysulfone ultrafiltration membrane in ultrapure water, wash it, blow it dry, immerse it in the aqueous solution of step (1) for 2 min, remove the surface water droplets, immerse it in the acyl chloride solution of step (2), and after 20 s, a dense polyamide layer is formed. Then, place it at 60℃ for heat treatment for 2 min.

[0135] Using 2000ppm Na2SO4 and NaCl aqueous solutions as test solutions, the prepared polyamide nanocomposite membrane with high charge distribution channels was continuously filtered for 1h under an operating pressure of 145psi. The performance of the composite membrane was tested, and the results are shown in Table 1.

[0136] Table 1. Ion sieving performance of the high-performance polyamide nanocomposite membrane prepared in this invention.

[0137]

[0138] In this embodiment of the invention, the single salt solution test conditions are as follows: 2000 ppm MgCl2 or LiCl or Na2SO4 or NaCl aqueous solution is used as the test solution, and the prepared polyamide membrane is continuously filtered for 1 hour at an operating pressure of 145 psi and a temperature of 25°C to test its performance.

[0139] b MgCl2+LiCl test conditions: A mixed salt solution of 1866ppm MgCl2 and 134ppm LiCl was used as the test solution. The prepared polyamide membrane was pre-pressed for 0.5h at 145psi operating pressure and 25℃, and its LiCl content was then tested. + / Mg 2+ Selectivity;

[0140] cNa₂SO₄ + NaCl test conditions: A mixed salt solution of 1000 ppm Na₂SO₄ + 1000 ppm NaCl was used as the test solution. The prepared polyamide membrane was pre-pressed for 0.5 h at an operating pressure of 145 psi and a temperature of 25 °C, and its Cl₂ content was then tested. - SO4 2- Selectivity.

[0141] In an embodiment of the present invention, Figure 4 This is a schematic diagram of the charge density of the composite films prepared in Comparative Examples 1, 4 and 11 provided in the embodiments of the present invention.

[0142] Example 14, as another possible embodiment of the present invention, provides a method for preparing a polyamide nanocomposite membrane with high charge distribution channels. This method involves designing UIO-66-NH2 nanoporous fillers modified with different charged groups using a post-modification strategy. The soluble charged nanoporous fillers are uniformly dispersed between polyamide polymer chains, coordinating the microstructure and charge of the polyamide separation layer. The method specifically includes the following steps:

[0143] S1, Dissolve the organic amine in water to prepare an organic amine solution with a mass concentration of 0.05%, then add 0.005% of a high charge density UIO-66-NH2 derivative, 1.0 wt% of triethylamine and 2.0 wt% of camphor sulfonic acid to the organic amine solution, stir thoroughly, and then disperse by ultrasonication to obtain an aqueous solution;

[0144] S2, Immerse the ultrafiltration membrane in the aqueous solution from step S1, soak for 1 minute, then remove it and use an air knife or rubber roller to dry the residual aqueous solution on the surface of the ultrafiltration membrane.

[0145] S3, an organic acyl chloride solution was prepared using 0.01 wt% polyacyl chloride, 0.2 wt% tributyl phosphate and 0.2 wt% acetone. The upper surface of the membrane obtained in step S2 was immersed in the organic acyl chloride solution and an interfacial polymerization reaction was carried out for 10 s to form a polyamide separation layer. After the reaction was completed, the remaining organic acyl chloride solution was discarded.

[0146] S4. The membrane obtained in step S3 is placed in a 60°C oven for thermal crosslinking for 1 min and then removed to obtain a polyamide nanocomposite membrane with high charge distribution channels.

[0147] Example 15, as another possible embodiment of the present invention, provides a method for preparing a polyamide nanocomposite membrane with high charge distribution channels. This method involves designing UIO-66-NH2 nanoporous fillers modified with different charged groups using a post-modification strategy. The soluble charged nanoporous fillers are uniformly dispersed between polyamide polymer chain segments, coordinating the microstructure and charge of the polyamide separation layer. The method specifically includes the following steps:

[0148] S1, Dissolve the organic amine in water to prepare an organic amine solution with a mass concentration of 2.055 wt%. Then add 1.0 wt% of a high charge density UIO-66-NH2 derivative, 1.15 wt% of triethylamine and 2.3 wt% of camphor sulfonic acid to the organic amine solution, stir thoroughly, and then disperse by ultrasonication to obtain an aqueous solution.

[0149] S2, Immerse the ultrafiltration membrane in the aqueous solution from step S1, soak for 5 minutes, then remove it and use an air knife or rubber roller to dry the residual aqueous solution on the surface of the ultrafiltration membrane.

[0150] S3, an organic acyl chloride solution was prepared using 0.2 wt% polyacyl chloride, 0.5 wt% tributyl phosphate and 0.5 wt% acetone. The upper surface of the membrane obtained in step S2 was immersed in the organic acyl chloride solution and an interfacial polymerization reaction was carried out for 55 s to form a polyamide separation layer. After the reaction was completed, the remaining organic acyl chloride solution was discarded.

[0151] S4. Place the membrane obtained in step S3 in an 80℃ oven for thermal crosslinking for 5 minutes, then remove it to obtain a polyamide nanocomposite membrane with highly charged pores.

[0152] Example 16, as another possible embodiment of the present invention, provides a method for preparing a polyamide nanocomposite membrane with high charge distribution channels. This method involves designing UIO-66-NH2 nanoporous fillers modified with different charged groups using a post-modification strategy. The soluble charged nanoporous fillers are uniformly dispersed between polyamide polymer chains, coordinating the microstructure and charge of the polyamide separation layer. The method specifically includes the following steps:

[0153] S1, Dissolve the organic amine in water to prepare an organic amine solution with a mass concentration of 4wt%, then add 2wt% of a high charge density UIO-66-NH2 derivative, 2.3wt% of triethylamine and 4.6wt% of camphor sulfonic acid to the organic amine solution, stir thoroughly, and then disperse by ultrasonication to obtain an aqueous solution;

[0154] S2, Immerse the ultrafiltration membrane in the aqueous solution from step S1, soak for 10 minutes, then remove it and use an air knife or rubber roller to dry the residual aqueous solution on the surface of the ultrafiltration membrane.

[0155] S3, an organic acyl chloride solution was prepared using 0.4 wt% polyacyl chloride, 1 wt% tributyl phosphate and 1 wt% acetone. The upper surface of the membrane obtained in step S2 was immersed in the organic acyl chloride solution and an interfacial polymerization reaction was carried out for 100 s to form a polyamide separation layer. After the reaction was completed, the remaining organic acyl chloride solution was discarded.

[0156] S4. The membrane obtained in step S3 is placed in a 100°C oven for thermal crosslinking for 10 min and then removed to obtain a polyamide nanocomposite membrane with high charge distribution channels.

[0157] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0158] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention and within the spirit and principles of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A polyamide nanocomposite membrane with highly charged pores, characterized in that, The polyamide nanocomposite membrane with high charge distribution channels is composed of an ultrafiltration base membrane and a polyamide dense layer hybridized with charged nanoporous metal-organic frameworks (MOFs). The charged nanoporous metal-organic framework (MOF) hybrid polyamide dense layer is formed by the polymerization of aqueous amine solution and oil-phase organic acyl chloride solution at the surface interface of the ultrafiltration base membrane. The ultrafiltration membrane includes a porous support layer, which is a polysulfone ultrafiltration membrane, a polyethersulfone ultrafiltration membrane, or a polyacrylonitrile ultrafiltration membrane prepared by phase inversion on the surface of a nonwoven fabric; the aqueous amine solution is a mixed solution of an organic amine and a UIO-66-NH2-based derivative with high charge density; the charged UIO-66-NH2-based derivative is at least one of quaternary ammonium or sulfonic acid-modified UIO-66-NH2-based derivatives. The porous support layer was successively immersed in an aqueous amine solution and an oil-phase organic acyl chloride solution, and then polymerized at the interface to form a dense polyamide layer hybridized with charged nanoporous metal-organic frameworks (MOFs). The modifying reagent required for preparing UIO-66-NH2-based derivatives modified with quaternary ammonium or sulfonic acid groups is at least one of 1,3-propylsulfonate lactone, 1,4-butanesulfonate lactone, 2,3-epoxypropyltrimethylammonium chloride, epioxypropyltriethylammonium chloride, dodecyl dimethyl epioxypropylammonium chloride, 3-chloro-2-hydroxypropyltriethylammonium chloride, and O-methacryloyl-oxyethyl dimethyl epioxypropylammonium chloride. The organic acyl chloride monomer is one or more of the following: pyromellitic acid tricarboxylic acid chloride, 1,2,3,4-cyclobutanetetracarboxylic acid chloride, 1,2,4,5-cyclohexanetetracarboxylic acid chloride, 1,3,5-cyclohexanetricarboxylic acid chloride, and 1,2,3,4-cyclopentanetetracarboxylic acid chloride.

2. The polyamide nanocomposite membrane with high charge distribution channels according to claim 1, characterized in that, The organic amine monomer is one or more of piperazine, tris(2-aminoethyl)amine, m-phenylenediamine, polyethyleneimine, 2,5-dimethylpiperazine, (1R,2R)-(-)-1,2-cyclohexanediamine, 1,2-cyclohexanediamine, 2,6-dimethylpiperazine, and 1,4-cyclohexanediamine.

3. The polyamide nanocomposite membrane with high charge distribution channels according to claim 2, characterized in that, The organic solvent used to prepare the aqueous amine solution is at least one of cyclohexane, n-hexane, n-heptane, ISOPAR-G, ISOPAR-E, and ISOPAR-H.

4. A method for preparing a polyamide nanocomposite film, characterized in that, This method prepares the polyamide nanocomposite membrane with high charge distribution channels as described in any one of claims 1-3. The method employs a post-modification strategy to design UIO-66-NH2 nanoporous fillers modified with different charged groups. The soluble charged nanoporous fillers are uniformly dispersed between polyamide polymer chains, coordinating the microstructure and charge of the polyamide separation layer. Specifically, the method includes the following steps: S1, Dissolve organic amine in water to prepare an organic amine solution with a mass concentration of 0.05%-4 wt%, then add 0.005%-2 wt% of high charge density UIO-66-NH2 derivative, 0-2.3 wt% of triethylamine and 0-4.6 wt% of camphor sulfonic acid to the organic amine solution, stir thoroughly, and then disperse by ultrasonication to obtain an aqueous solution; S2, Immerse the ultrafiltration membrane in the aqueous solution from step S1 for 1-10 minutes, then remove it and use an air knife or rubber roller to dry the residual aqueous solution on the surface of the ultrafiltration membrane. S3, prepare an organic acyl chloride solution using 0.01-0.4 wt% polyacyl chloride, 0-1 wt% tributyl phosphate and 0-1 wt% acetone, immerse the upper surface of the membrane obtained in step S2 in the organic acyl chloride solution, and carry out interfacial polymerization reaction for 10-100s to form a polyamide separation layer. After the reaction is completed, discard the remaining organic acyl chloride solution. S4. Place the membrane obtained in step S3 in an oven at 60-100℃ for thermal crosslinking for 1-10 minutes, and then remove it to obtain a polyamide nanocomposite membrane with high charge distribution channels.

5. The method for preparing the polyamide nanocomposite film according to claim 4, characterized in that, In step S1, the preparation of the high charge density UIO-66-NH2-based derivative includes: adding an appropriate amount of UIO-66-NH2 to methanol, stirring and sonicating, adding sulfonyl lactones or epoxy quaternary ammonium salts, reacting at 40-80 °C for 4-12 h, and then centrifuging, washing, and freeze-drying the product to obtain the charged UIO-66-NH2-based derivative. The structure of the charged UIO-66-NH2-based derivative is as follows: 。 6. The method for preparing the polyamide nanocomposite film according to claim 5, characterized in that, In the preparation of the charged UIO-66-NH2-based derivative, the sulfonate lactone small molecule is one of 1,3-propylsulfonate lactone and 1,4-butanesulfonate lactone. The epoxy quaternary ammonium salt small molecule is one of 2,3-epoxypropyltrimethylammonium chloride, epioxypropyltriethylammonium chloride, dodecyl dimethylepoxypropylammonium chloride, 3-chloro-2-hydroxypropyltriethylammonium chloride, and O-methacryloyl-oxyethyldimethylepoxypropylammonium chloride.

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