Preparation method and application of membrane separation material based on external field enhanced water isotope separation

Abstract

The invention discloses a preparation method and application of a membrane separation material based on external field enhanced water isotope separation. The preparation method comprises the following steps: firstly, pre-enriching a precursor component containing a polymerizable monomer, a cross-linking agent and a photoinitiator in a confinement pore channel of a nano-porous carrier through an impregnation-encapsulation strategy; and then, through in-situ photo-initiation polymerization, a covalent cross-linked functional polymer network is constructed in the pore channel, and stable packaging of the polymer is realized. In the water isotope separation period, external field conditions are regulated and controlled, the molecular conformation of a polymer chain is accurately controlled, and the separation performance is optimized. According to the invention, by virtue of an external field strengthening technology, the intramolecular / intermolecular interaction is destroyed, and the macromolecular chain is converted from contraction to stretching, so that more functional sites are exposed, and the water isotope separation material designed by the invention has a huge practical application prospect.

Description

Technical Field

[0001] This invention relates to the field of materials preparation, specifically to a method for preparing and applying a membrane separation material based on external field-enhanced water isotope separation. Background Technology

[0002] Water isotopes (water, deuterium-water, and tritium-water) are strategic resources supporting the development of cutting-edge technologies such as nuclear fusion energy. However, due to the extremely slight differences in the inherent physicochemical properties between isotopes, traditional separation technologies relying on these differences have always faced bottlenecks of high energy consumption and low efficiency. The Chemical Affinity Quantum Separation (CAQS) strategy based on a nano-confined environment amplifies the differences in the interactions between water isotopes and specific interaction sites, causing differences in the dynamic diffusion of water isotopes, thus providing a new paradigm for solving this problem. However, its final performance is highly dependent on the density, stability, and accessibility of functional sites within the confined interface. To address these issues, mainstream "top-down" interface modification methods, i.e., secondary regulation within the confined space, generally face the dilemma of "low density and poor stability" of functional sites in methods such as adsorption, deposition, grafting, and blending. Compared to the aforementioned regulation technologies, in-situ polymerization of functional monomers within confined channels has become a highly promising advanced strategy. This method cleverly bypasses many bottlenecks of traditional modification methods: 1) High versatility: It does not require the surface of the carrier material to have special chemical reactivity and can be widely used in various porous platforms; 2) Excellent stability: By forming a micro-crosslinked network, the functional components are firmly anchored in the pores, avoiding the problem of dissolution or loss of the functional layer in the physical adsorption method.

[0003] CN113336897A discloses a metal-organic framework-based material for in-situ confined polymerization of organic monomers, its preparation method, and its application. The method involves placing organic monomers, lithium salts, and initiators within the pores of the metal-organic framework material for in-situ confined polymerization. This encapsulates conductive ions within the pores of the metal-organic framework material, achieving high ion conductivity. Using the material provided by this invention as an all-solid-state electrolyte avoids the leakage problem present in traditional electrolytes and improves the material's electrochemical window, exhibiting high ionic conductivity. Furthermore, assembling the all-solid-state electrolyte into a battery reduces internal polarization, minimizes side reactions, and ensures stable cycle performance. The battery exhibits high capacity and slow capacity decay at high rates, extending battery life. This method can be widely applied in lithium battery systems, significantly improving the energy density and safety performance of existing lithium batteries.

[0004] CN117467070A discloses a method for preparing a tear-resistant elastic gel, comprising the following steps: adding monomer molecules, a crosslinking agent, and a nano-confined material to a solvent, and performing a polymerization reaction under ultraviolet light irradiation in the presence of a photoinitiator to obtain the tear-resistant elastic gel. This invention utilizes the polymerization of monomer molecules and crosslinking agents initiated by a photoinitiator within the confined space of the nano-confined material. The strong hydrogen bonding between interpenetrating polymer segments effectively immobilizes polymer chains that may slide under load, preventing energy dissipation. Simultaneously, the rigid nano-confined material prevents stress concentration at crack tips in the host material and significantly reduces the crack propagation sensitivity of the prepared gel, thereby improving the strength, strain, crack propagation resistance, and elasticity under ultimate deformation of the gel material to prepare a tear-resistant elastic gel.

[0005] However, the actual effectiveness of this strategy is often constrained by a fundamental physicochemical problem: in a confined environment, polymer chains are limited by entropy effects and intramolecular / intermolecular van der Waals forces or electrostatic attraction, making them prone to self-aggregation and a change in molecular conformation from an "extended" to a "contracted" state. This process brings two negative impacts: 1) Internal shielding: a large number of functional groups are trapped within the contracted polymer core, losing the opportunity to contact the outside environment; 2) Incomplete coverage: the polymer forms isolated "islands" rather than a uniform functional layer within the pores, resulting in an actual effective functionalized surface area far lower than the theoretical value. Therefore, most existing confined polymerization methods actually face the under-considered dilemma of "a large amount of redundancy and waste of functional sites." A considerable portion of the introduced functional groups are in a "dormant" state and do not contribute to the separation process, directly resulting in the material's water isotope processing capacity falling far short of its theoretical potential. Solving this problem is key to unlocking the full potential of confined polymerization strategies. Summary of the Invention

[0006] To address the aforementioned problems, this invention proposes a method for preparing membrane separation materials based on external field-enhanced water isotope separation. This method first pre-enriches polymerizable monomers, photoinitiators, and crosslinking agents into the pores of a nanoporous carrier, followed by vacuum filtration to form a membrane. Subsequently, in-situ photoinitiated polymerization is used to polymerize functional monomers into the pores, achieving polymer encapsulation. Finally, by controlling external field conditions (temperature field, ion field, pH field, and electric field), the molecular conformation of the polymer chains is optimized, thereby improving the water isotope separation performance of the material.

[0007] To address the bottlenecks in existing technologies for water isotope separation, this invention discloses a method for preparing membrane separation materials based on external field-enhanced water isotope separation.

[0008] The technical solution adopted in this invention is as follows: I. A method for preparing membrane separation materials based on external field-enhanced water isotope separation S1. A homogeneous and transparent aqueous solution of the polymerization precursor is prepared by dissolving the polymerizable monomer, crosslinking agent, and photoinitiator in ultrapure water at a specific mass ratio. Subsequently, the pre-prepared nanoporous support is dispersed in the polymerizable precursor aqueous solution and magnetically stirred continuously at room temperature for 0.5–24 hours to obtain a mixed solution. This process aims to utilize the concentration gradient to drive the sufficient diffusion and penetration of precursor molecules into the nano-confined pores of the nanoporous support, laying the foundation for subsequent in-situ polymerization. Specifically, the mass ratio of polymerizable monomer, crosslinking agent, and photoinitiator ranges from 10:1:1 to 100:1:1; the mass ratio of polymerizable monomer to nanoporous support ranges from 50:1 to 500:1.

[0009] The polymerizable monomer is one or more of ionic liquids, zwitterions, and eutectic solvents; the crosslinking agent is one or more of N,N-methylenebisacrylamide, ethylene glycol dimethacrylate, pentaerythritol triacrylate, and pentaerythritol tetraacrylate; the photoinitiator is one or more of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, 2-hydroxy-2-methyl-1-phenyl-1-propanone, 2-hydroxy-4-(2-hydroxyethoxy)-2-methylphenylpropanone, and benzoin methyl ether; and the nanoporous support is one or more of covalent organic frameworks (COFs), metal-organic frameworks (MOFs), porous aromatic frameworks (PAFs), intrinsic microporous polymers (PIMs), and porous coordination polymers (PCPs).

[0010] Further, the ionic liquid is one or more of the following: 1-allyl-3-methylimidazolium chloride, 1-vinyl-3-ethylimidazolium bromide, 1-vinyl-3-benzylimidazolium chloride, 1-vinyl-3-ethylimidazolium dinitrile amine salt, 1-vinyl-3-butylimidazolium dichloride, 1-vinyl-3-hexylimidazolium bromide, and 1-allyl-3-vinylimidazolium salt.

[0011] Further, the zwitterion is at least one of 3-[[2-(methacryloyloxy)ethyl]dimethylammonium]propionate, 2-methacryloyloxyethyl phosphoric acid choline, 2-methacryloyloxyethyl phosphoric acid choline, sulfobetaine acrylamide, 3-[N,N-dimethyl-[2-(2-methylprop-2-enoyloxy)ethyl]ammonium]propane-1-sulfonic acid inner salt, and sulfobetaine [dimethyl-(4-vinylphenyl)]ammonium propane sulfonate.

[0012] Furthermore, the eutectic solvent is a 3-[N,N-dimethyl-[2-(2-methylprop-2-enoyloxy)ethyl]ammonium]propane-1-sulfonic acid inner salt-ethylene glycol system, lipoic acid-choline chloride system, hydroxyethyl acrylate-choline chloride-itaconic acid system, diallyl dimethyl ammonium chloride-urea system, hydroxyethyl methacrylate-choline chloride system, lithium bis(trifluoromethanesulfonyl)imide-N-cyanomethylacrylamide system, trifluoroethyl acrylate-bis(trifluoromethanesulfonyl)imide-lithium system, tetramethylammonium chloride-acrylic acid system, acrylic acid-choline chloride system, maleic acid-choline chloride system, and lithium bis(trifluoromethanesulfonyl)imide-acrylic acid system.

[0013] S2. The mixed solution is vacuum filtered to obtain a filter membrane. The filter membrane is then irradiated under ultraviolet light for a period of time to obtain a sample. The sample is then repeatedly centrifuged, washed, and dried to obtain a separation membrane.

[0014] Specifically, the mixed solution is vacuum filtered to remove excess aqueous solution of polymerization precursor from the surface and outside the pores of the nanoporous support, ensuring that the polymerization reaction occurs only inside the pores of the nanoporous support, thus obtaining a filter membrane. The obtained filter membrane is then subjected to irradiation polymerization under ultraviolet light for 1 min to 120 min, initiating in-situ polymerization of polymerizable monomers within the pores of the nanoporous support, thereby constructing a cross-linked functional polymer network within the confined pores, thus obtaining a sample. After polymerization, to remove any unreacted monomers, initiators, and soluble oligomers, the sample is repeatedly centrifuged and washed three times with sufficient ultrapure water, and then dried under vacuum conditions for later use, thus obtaining a separation membrane.

[0015] S3. By regulating the external field conditions to activate the separation membrane prepared above, the extension / contraction state of the polymer chains can be precisely adjusted, thereby changing the effective pore size of the nanoporous carrier and the chemical environment of the pore wall, thus preparing a high-performance water isotope separation membrane material with external field-dependent separation characteristics. The external field conditions can be adjusted by controlling one of the following: temperature field, ion field, pH field, or electric field.

[0016] In practice, the temperature field is controlled within a range of 25 ℃ to 90 ℃; the salt ion concentration in the ion field is controlled within a range of 0.1 mol / L to 2 mol / L; the pH field is controlled within a range of 3 to 9; and the voltage in the electric field is controlled within a range of 0.1 V to 1 V. During this process, the interactions between functional groups on polymer chains in the functional polymer network within the confined channels change, inducing specific conformational rearrangements in the functional polymer network within the confined channels.

[0017] The core technology of the preparation method of this invention lies in the following: First, through an impregnation-encapsulation strategy, precursor components comprising polymerizable monomers, crosslinking agents, and photoinitiators are pre-enriched within the confined pores of a nanoporous carrier. Then, through in-situ photoinitiated polymerization, a covalently crosslinked functional polymer network is constructed within the pores, achieving stable encapsulation of the polymer. During water isotope separation, external field conditions are controlled to precisely regulate the molecular conformation of the polymer chains, optimizing their separation performance.

[0018] The "impregnation-in-situ polymerization" strategy not only ensures the stable anchoring of functional components within the pores but also eliminates the need for complex chemical pre-activation of the carrier substrate, thus overcoming the limitations of traditional physical adsorption or chemical grafting modification methods in terms of stability and universality. More importantly, in the confined environment, polymer chains are restricted by entropy effects and interactions such as intramolecular / intermolecular van der Waals forces or electrostatic attraction, and the shrinkage of molecular chains leads to the shielding of functional sites.

[0019] The control of external field conditions specifically involves controlling the external field environment, such as temperature field, ion field, pH field, and electric field, which can induce a conformational change in polymer chains from "shrinking" to "stretching". This dynamic process not only breaks the limitations of traditional static modification, but also achieves two major synergistic effects: (1) Functional activation: The "stretching" conformation effectively overcomes the inter-chain shielding effect and exposes the active sites to the maximum extent; (2) Pore size fine-tuning: The stretching of the chains synchronously and precisely shrinks the effective mass transfer pore size. This "smart switch" type of confined environment reconstruction is expected to endow the composite material with excellent water isotope recognition and separation capabilities, and achieve a significant improvement in separation performance.

[0020] The core strategy of this invention lies in two steps: First, by utilizing the low diffusion and mass transfer resistance of small molecule components such as functional monomers and crosslinking agents, efficient pre-enrichment is achieved within the pores of a nanoporous support. Then, in-situ photo-initiated polymerization is used to construct a stable micro-crosslinked polymer network within the confined space. This "impregnation-in-situ polymerization" strategy not only ensures the stable anchoring of functional components within the pores but also eliminates the need for complex chemical pre-activation of the support substrate, thus overcoming the limitations of traditional physical adsorption or chemical grafting modification methods in terms of stability and universality. More importantly, in the confined environment, the polymer chains are restricted by entropy effects and interactions such as intramolecular / intermolecular van der Waals forces or electrostatic attraction, leading to chain contraction and shielding of functional sites.

[0021] II. A membrane separation material based on external field-enhanced water isotope separation The membrane separation material based on external field enhanced water isotope separation was prepared by the above preparation method.

[0022] III. Applications of Membrane Separation Materials Based on External Field Enhanced Water Isotope Separation Applications of membrane separation materials based on field-enhanced water isotope separation in water isotope extraction, wastewater treatment, seawater desalination, and drug purification.

[0023] The beneficial effects of this invention are: 1. The movement of polymerizable monomer molecules is restricted in confined spaces due to interactions such as van der Waals forces and electrostatic attraction between / within polymer chain molecules. The shrinkage of molecular chains leads to the shielding of functional sites. The method of this invention uses an external field enhancement strategy to disrupt the interactions between molecular chains, enabling the polymer chains to transform from shrinkage to expansion, thereby exposing more functional sites and efficiently achieving water isotope separation.

[0024] 2. The method of the present invention utilizes external field enhancement technology to disrupt intramolecular / intermolecular interactions, enabling the polymer chain to transition from contraction to extension, thereby exposing more functional sites. Therefore, the water isotope separation material designed in this invention has great potential for practical applications. Attached Figure Description

[0025] Figure 1 This is a flowchart of a method for preparing membrane separation materials based on external field-enhanced water isotope separation. Figure 2 Diagram of the field reinforcement mechanism; Figure 3 This is an infrared spectrum; Figure 4 The water isotope separation factor and permeation flux of the membrane separation materials prepared in Examples 2-4; Figure 5 The water isotope separation factor and permeation flux of the membrane separation materials prepared in Examples 5-8; Figure 6 The water isotope separation factor and permeation flux of the membrane separation materials prepared in Examples 9-12; Figure 7 The water isotope separation factor and permeation flux of the membrane separation materials prepared in Examples 13-17; Figure 8 The water isotope separation factor and permeation flux of the membrane separation materials prepared in Examples 18-21; Figure 9 The water isotope separation factor and permeation flux of the membrane separation materials prepared in Examples 22-28; Figure 10 The water isotope separation factor and permeation flux of the membrane separation materials prepared in Examples 29-33 are shown. Detailed Implementation

[0026] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] Example 1: like Figure 1 and Figure 2 As shown, firstly, a polymerization precursor solution was prepared. Specifically, at room temperature, 0.2 g of the zwitterionic monomer (3-[[2-(methacryloyloxy)ethyl]dimethylammonium]propionate, hereinafter referred to as SBMA), 0.01 g of the crosslinking agent (N,N-methylenebisacrylamide, MBAA), and 0.01 g of the photoinitiator (2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone) were sequentially dissolved in 100 mL of ultrapure water to form a homogeneous and transparent solution. Subsequently, 1 mg of sulfonic acid-functionalized covalent organic framework (TpBd-HSO3 COF) was dispersed in the above precursor solution as a nanoporous carrier, and the mixture was continuously magnetically stirred at room temperature for 12 hours. This step aims to utilize molecular diffusion to ensure that the precursor components can fully penetrate and enrich within the nanopores of the COF. After removing the unencapsulated bulk solution by vacuum filtration, the resulting filter membrane was irradiated under a UV lamp for 5 minutes to trigger an in-situ polymerization reaction within the pores. After polymerization, to completely remove any physically adsorbed or unreacted components, the sample was purified by multiple centrifugal washings with ultrapure water, and finally vacuum dried to obtain the polymer-functionalized COF composite material, denoted as pSBMA@TpBd-HSO3. Finally, to obtain the final material with water isotope separation capabilities, the prepared pSBMA@TpBd-HSO3 separation membrane was activated by immersing it in a 1 mol / L NaCl aqueous solution. This step aims to optimize the separation environment of the nanochannel by utilizing salt ions to regulate the molecular conformation of the confined polymer chains.

[0028] Experimental Example 1: The structure of the material prepared in Example 1 was characterized. Figure 3 Infrared spectroscopy tests revealed that the intensity of the characteristic peak of O=S=O in the material was significantly enhanced after polymerization, indicating that the confined encapsulation of the polymer within the COF pores was successfully achieved.

[0029] Experimental Example 2: To evaluate the water isotope separation performance of the prepared membrane separation material, we conducted performance tests using a laboratory-standard dead-end filtration device. The separation membrane was placed in the device to form a separation layer. A mixed solution of 15 vol% deuterated water (D₂O) and 85 vol% ordinary water (H₂O) was used as the feed solution. Under a specific transmembrane pressure (e.g., 1 bar), the permeate passing through the separation layer was collected. By accurately analyzing the deuterium concentration in the feed solution and permeate, we used the internationally accepted separation factor (α) to quantify the material's separation capability. The calculation formula is as follows: C D2O —The concentration of deuterium in water, CH2O —Water concentration, f—feed source end, p—permeation end.

[0030] Experimental results show that the material exhibits a separation factor as high as 5.457. This reveals that its nanochannels have a significant preferential permeability to H2O molecules. Simultaneously, we measured the water permeation flux of the material. The results show that while exhibiting high selectivity, the material still maintains a high water permeation flux of 120.2 L / m / h / bar.

[0031] Examples 2-4: The mass ratio of polymerizable monomer to crosslinking agent / initiator was controlled at 10:1, 40:1, and 100:1, respectively, with the other conditions being the same as in Example 1.

[0032] The quality of Examples 2-4 is shown in Table 1; the deuterium-water separation performance and permeation flux of the membrane separation materials prepared in Examples 2-4 were tested using the method described in Example 1, and the results are shown in Table 1 and... Figure 4 As shown.

[0033] Table 1 As shown in Table 1, the membrane separation materials prepared by the mass ratio involved in this invention all have a water isotope separation factor of 4 or higher, and the permeation flux is maintained at 100 L / m. 3 The above / h / bar indicates that changing the mass ratio of polymerizable monomer to crosslinking agent / initiator has an effect on the performance of membrane separation materials.

[0034] Examples 5-8: The mass ratio of polymerizable monomer to nanoporous carrier was controlled at 50:1, 100:1, 300:1, and 500:1, respectively, with the other conditions being the same as in Example 1.

[0035] The quality of Examples 5-8 is shown in Table 2; the deuterium-water separation performance and permeation flux of the membrane separation materials prepared in Examples 5-8 were tested using the method of Example 1, and the results are shown in Table 2. Figure 5 As shown.

[0036] Table 2 As shown in Table 2, the membrane separation materials prepared by the mass ratio involved in this invention all have a water isotope separation factor of 4 or higher, and the permeation flux is maintained at 100 L / m. 3 The above / h / bar indicates that changing the mass ratio of polymerizable monomer to crosslinking agent / initiator has an effect on the performance of membrane separation materials.

[0037] Examples 9-12: The UV polymerization time was controlled at 1 min, 30 min, 60 min, and 120 min, respectively, with the other conditions being the same as in Example 1.

[0038] The quality of Examples 9-12 is shown in Table 3; the deuterium-water separation performance and permeation flux of the materials prepared in Examples 9-12 were tested using the method of Example 1, and the results are shown in Table 3. Figure 6 As shown.

[0039] Table 3 As shown in Table 3, the membrane separation materials prepared by the ultraviolet light polymerization time involved in this invention all have a water isotope separation factor of 4 or higher, and the permeation flux is maintained at 100 L / m. 3 The above / h / bar indicates that changing the UV polymerization time improves the performance of the membrane separation material.

[0040] Examples 13-17: Instead of immersing the separation membrane in a salt ion solution for activation, the external temperature was changed. The external temperature was controlled at 25 ℃, 40 ℃, 60 ℃, 75 ℃, and 90 ℃, with other conditions the same as in Example 1.

[0041] The quality of Examples 13-17 is shown in Table 4; the deuterium-water separation performance and permeation flux of the materials prepared in Examples 13-17 were tested using the method of Example 1, and the results are shown in Table 4. Figure 7 As shown.

[0042] Table 4 As shown in Table 4, the membrane separation materials prepared by the temperature method involved in this invention all have a water isotope separation factor of 4 or higher, and the permeation flux is maintained at 100 L / m. 3 The values ​​above / h / bar indicate that changing the temperature improves the performance of the membrane separation material.

[0043] Examples 18-21: The salt ion concentrations were controlled at 0.1 mol / L, 0.2 mol / L, 0.5 mol / L, and 2 mol / L, respectively, with other conditions the same as in Example 1. The mass ratios of Examples 18-21 are shown in Table 5. The deuterium-water separation performance and permeation flux of the materials prepared in Examples 18-21 were tested using the method described in Example 1, and the results are shown in Table 5. Figure 8 As shown.

[0044] Table 5 As shown in Table 5, the membrane separation materials prepared using the salt ion concentrations involved in this invention all have a water isotope separation factor of 4 or higher, and the permeation flux is maintained at 100 L / m. 3 The values ​​above / h / bar indicate that changing the salt ion concentration improves the performance of the membrane separation material.

[0045] Examples 22-28: Instead of immersing the separation membrane in a salt ion solution for activation, the pH value was changed. The pH was controlled at 3, 4, 5, 6, 7, 8, and 9, with other conditions the same as in Example 1. The quality results of Examples 22-28 are shown in Table 5. The deuterium-water separation performance and permeation flux of the materials prepared in Examples 22-28 were tested using the method of Example 1, and the results are shown in Table 5. Figure 9 As shown.

[0046] Table 5 As shown in Table 5, the pH-prepared membrane separation materials involved in this invention all have a water isotope separation factor of 4 or higher, and the permeation flux is maintained at 100 L / m. 3 The values ​​above / h / bar indicate that changing the pH value improves the performance of the membrane separation material.

[0047] Examples 29-33: Instead of immersing the separation membrane in a salt ion solution for activation, the external field voltage was changed. The electric field voltage was controlled at 0.1 V, 0.2 V, 0.5 V, 0.7 V, and 1 V, respectively, with other conditions the same as in Example 1. The quality results of Examples 29-33 are shown in Table 5. The deuterium-water separation performance and permeation flux of the materials prepared in Examples 29-33 were tested using the method of Example 1, and the results are shown in Table 6. Figure 10 As shown.

[0048] Table 6 As shown in Table 5, the membrane separation materials prepared by voltage according to the present invention all have a water isotope separation factor of 4 or higher, and the permeation flux is maintained at 100 L / m. 3 The values ​​above / h / bar indicate that changing the voltage improves the performance of the membrane separation material.

Claims

1. A method for producing a membrane separation material for enhancing water isotope separation based on an external field, characterized by, The method comprises the following steps: S1, dissolving polymerizable monomers, cross-linking agents and photoinitiators in ultrapure water to prepare a polymer precursor aqueous solution; then, dispersing a nanoporous carrier in the polymer precursor aqueous solution, continuously stirring under magnetic force at room temperature for a period of time to obtain a mixed solution; S2, vacuum suction filtering the mixed solution to obtain a filter membrane, and then irradiating the filter membrane under ultraviolet light for a period of time to obtain a sample, and then repeatedly centrifuging and washing the sample and drying to obtain a separation membrane; S3, activating the separation membrane prepared in the above step by adjusting external field conditions to prepare a membrane separation material for water isotope separation with external field-dependent separation characteristics.

2. The method for preparing a membrane separation material based on external field-enhanced water isotope separation according to claim 1, characterized in that, The step S2 is specifically: vacuum suction filtering the mixed solution to remove the excess polymer precursor aqueous solution on the surface and channels of the nanoporous carrier to obtain a filter membrane; then irradiating the filter membrane under ultraviolet light for a period of time to initiate in-situ polymerization of the polymerizable monomers in the channels of the nanoporous carrier, thereby constructing a cross-linked functional polymer network in the confined channels to obtain a sample; after the polymerization is completed, repeatedly centrifuging and washing the sample with ultrapure water, and then drying under vacuum to obtain a separation membrane.

3. The method according to claim 1, characterized in that: in the step S1, the polymerizable monomers are a mixture of one or more of ionic liquids, zwitterions and deep eutectic solvents; the cross-linking agent is a mixture of one or more of N,N-methylenebisacrylamide, ethylene glycol dimethacrylate, pentaerythritol triacrylate and pentaerythritol tetraacrylate; the photoinitiator is a mixture of one or more of 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, phenyl bis(2,4,6-trimethylbenzoyl)phosphine oxide, 2-hydroxy-2-methyl-1-phenyl-1-propanone, 2-hydroxy-4-(2-hydroxyethoxy)-2-methylpropiophenone and benzoin methyl ether; and the nanoporous carrier is a mixture of one or more of covalent organic frameworks, metal-organic frameworks, porous aromatic frameworks, intrinsic microporous polymers and porous coordination polymers.

4. The method according to claim 1, characterized in that: in the step S1, continuously stirring under magnetic force at room temperature for 0.5-24 hours.

5. The method according to claim 1, characterized in that: in the step S1, the mass ratio of the polymerizable monomers, the cross-linking agent and the photoinitiator is in the range of 10:1:1-100:1:1; and the mass ratio of the polymerizable monomers to the nanoporous carrier is in the range of 50:1-500:

1.

6. The method according to claim 2, characterized in that: in the step S2, the ultraviolet irradiation time is in the range of 1 min-120 min; and the sample is repeatedly centrifuged and washed with ultrapure water for 3 times. 7.The method for preparing a membrane separation material based on external field reinforced water isotope separation according to claim 1, characterized in that: in the step S3, the external field condition is one of a temperature field, an ion field, a pH field, and an electric field. 8.The method for preparing a membrane separation material based on external field reinforced water isotope separation according to claim 7, characterized in that: in the step S3, the temperature of the temperature field is controlled in a range of 25 ℃ to 90 ℃, the salt ion concentration of the ion field is controlled in a range of 0.1 mol / L to 2 mol / L, the pH of the pH field is controlled in a range of 3 to 9, and the voltage of the electric field is controlled in a range of 0.1 V to 1 V. 9.A membrane separation material based on external field reinforced water isotope separation, characterized in that: it is prepared by the method according to any one of claims 1 to 8. 10.The application of a water isotope separation membrane separation material prepared by the method according to any one of claims 1 to 8, characterized in that: it is applied in water isotope extraction, sewage treatment, seawater desalination, and drug purification.

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