High-flux nanofiltration membrane suitable for iodide ion separation as well as preparation method and application of high-flux nanofiltration membrane

Abstract

The invention discloses a high-flux nanofiltration membrane suitable for iodide ion separation as well as a preparation method and application of the high-flux nanofiltration membrane. The nanofiltration membrane is prepared by taking an ultrafiltration membrane or an ultrafiltration membrane modified by a porous MOF material as a base membrane, taking an ethylene derivative as a membrane preparation monomer and adopting an ultraviolet radiation grafting method. The maximum removal rate of the nanofiltration membrane to 100 mg / LI <-> reaches 95% or above, even if chloride ions or sulfate ions exist in a solution, the removal rate of the membrane to iodide ions is good, the flux is far larger than that of a reverse osmosis membrane, the maximum removal rate can reach about 45 L / m < 2 >. H under 0.6 MPa, the flux is large, water is used as a solvent in the whole preparation process, and the nanofiltration membrane is environmentally friendly and free of pollution. The method is suitable for removing iodide ions in wastewater containing radioactive iodide ions and water areas with high iodide ion content, and has a good application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of nanofiltration membranes, and in particular relates to a high-flux nanofiltration membrane suitable for iodine ion separation, a preparation method and an application thereof. Background Art

[0002] Nuclear contaminated water contains 64 radioactive elements including iodine, strontium, cobalt, actinium and tritium. In addition, nuclear weapons testing and radioactive medical treatments also produce radioactive iodine-containing wastewater. It should be pointed out that the half-life of I-129 is about 15.7 million years, which is extremely harmful to humans and the ecological environment and can easily cause thyroid dysfunction in the human body.

[0003] It should be noted that an appropriate amount of iodine intake is beneficial to maintaining normal levels of thyroid hormones, preventing thyroid diseases, enhancing enzyme activity, promoting the absorption and utilization of vitamins, and promoting the development of the nervous system. However, excessive iodine intake can lead to metabolic disorders in the human body and increase the incidence of thyroid disease. In many coastal areas and areas where shale gas is being commercially developed on a large scale, iodine in the water is high. - The concentration has increased significantly and needs to be reduced urgently to ensure human health.

[0004] Common methods for reducing the concentration of iodine ions in water include adsorption, ion exchange, precipitation and membrane separation. Among them, the adsorption method is widely used, and the materials used involve composite materials containing Ag(I), metal organic framework compounds (MOFs), anion exchange resins, layered double hydroxides (LDHs), etc., with morphologies ranging from granular to two-dimensional membranes. However, most adsorbents have disadvantages such as high cost, difficult desorption, and complex subsequent treatment, which to a certain extent limit the use of the adsorption method. Compared with the adsorption method, the membrane separation technology has a simple principle and has the advantages of high efficiency, no phase change, small footprint, low energy consumption, and easy integration with other processes.

[0005] At present, the separation membrane used for iodine ion removal in production is reverse osmosis membrane, which has a high iodine removal rate, but a high operating pressure, generally 1-2 MPa, and a low flux. Usually, nanofiltration membranes achieve selective separation of inorganic salts based on pore size screening and charge repulsion effect, with a low removal rate for low-valent salts and a high removal rate for high-valent salts. Summary of the invention

[0006] The purpose of the present invention is to provide a high-flux nanofiltration membrane suitable for iodine ion separation and a preparation method thereof. A polysulfone ultrafiltration membrane with ultraviolet activity or a ZIF-8 modified polysulfone ultrafiltration membrane or an Ag / Ag2O@ZIF-8 modified polysulfone ultrafiltration membrane is used as a base membrane, and the free radicals generated by the above membrane under ultraviolet action are used to in-situ induce the graft polymerization of sodium styrene sulfonate on the membrane surface, and by increasing the amount of negative charge on the membrane surface, a nanofiltration membrane with high flux, high iodine ion removal rate and resistance to sulfate and chloride ions is constructed. Compared with the existing reverse osmosis membranes on the market, the iodine ion removal rate is similar, but the operating pressure is significantly reduced, the flux is large, the energy consumption is low, and the preparation process uses an aqueous solution throughout the process, which is green and environmentally friendly. The preparation process is simple and easy to implement, and the prospect of realizing the transformation of technology landing is good, providing a high-quality nanofiltration membrane for the removal of iodine ions, and also providing a new idea for constructing a nanofiltration membrane with a high monovalent ion removal rate.

[0007] The present invention is realized by the following technical scheme: A high flux nanofiltration membrane suitable for iodine ion separation, characterized in that it is prepared by ultrafiltration membrane or ultrafiltration membrane modified by porous MOF material as base membrane and ethylene derivatives as membrane monomers by ultraviolet irradiation grafting method.

[0008] More preferably, the ultrafiltration membrane is a polysulfone ultrafiltration membrane or a porous MOF material modified polysulfone ultrafiltration membrane. The ethylene derivative is sodium styrene sulfonate. The porous MOF material is ZIF-8 or Ag / Ag2O@ZIF-8.

[0009] The present invention also provides a method for preparing a high-throughput nanofiltration membrane suitable for iodide ion separation, comprising adding an ethylene derivative solution to a polysulfone ultrafiltration membrane or a porous MOF material modified polysulfone ultrafiltration membrane, in-situ irradiation grafting, simultaneous heat treatment for a period of time, cooling, and washing the obtained membrane.

[0010] Further preferably, the preparation process of the porous MOF material modified polysulfone ultrafiltration membrane is: fixing the polysulfone ultrafiltration membrane in the middle of a container; first adding 0.0159-0.0613 mol / L Zn(NO3)2 aqueous solution on the front side of the polysulfone ultrafiltration membrane, and then adding 0.1956-0.4890 mol / L 2-methylimidazole aqueous solution on the back side, the reactants diffuse with each other, the reaction time is 3-24 hours, and then washing with deionized water to obtain ZIF-8 modified polysulfone ultrafiltration membrane.

[0011] Further preferably, the preparation process of the porous MOF material modified polysulfone ultrafiltration membrane is as follows: first, the polysulfone ultrafiltration membrane is fixed in the middle of a container; a mixed solution of Zn(NO3)2 and AgNO3 is prepared, the concentration of the mixed solution is: 0.0159~0.0613mol / L Zn(NO3)2, 0.0039~0.0117mol / L AgNO3, 200mL of the mixed solution is first added to the front side of the polysulfone ultrafiltration membrane, and then 130mL of 0.1956~0.4890mol / L 2-methylimidazole aqueous solution is added to the back side, the reactants diffuse with each other, the reaction time is 3~24h, and then washed with deionized water to obtain Ag / Ag2O@ZIF-8 modified polysulfone ultrafiltration membrane.

[0012] Further preferably, the ethylene derivative solution is a sodium styrene sulfonate solution, a polysulfone ultrafiltration membrane or a ZIF-8 modified polysulfone ultrafiltration membrane or an Ag / Ag2O@ZIF-8 modified polysulfone ultrafiltration membrane is placed in a UV grafting mold, 40 mL of 0.5-1.0 mol / L sodium styrene sulfonate solution is added to the surface, and then placed under a UV lamp at a distance of 4-7 cm for irradiation grafting for 15 minutes, and finally the rear membrane is taken out from the UV grafting mold, and repeatedly washed with deionized water to remove residual monomers and homopolymers to obtain a high-flux nanofiltration membrane.

[0013] The invention also provides application of the high-flux nanofiltration membrane in iodine ion separation.

[0014] The present invention is different from ordinary nanofiltration membranes which have a high removal rate for high-valent ions but a low removal rate for low-valent ions. The present invention focuses on the following improvements to obtain a nanofiltration membrane with a high removal rate for iodide ions, a good iodide ion removal rate in a solution containing chloride ions or acid radical ions, and resistance to protein adsorption:

[0015] (1) Using sodium styrene sulfonate as raw material, the membrane surface charge is increased, the charge repulsion effect of the membrane on iodine ions is enhanced, and the removal rate of iodine ions is improved. Under the optimal conditions, the iodine ion removal rate reaches 92.6% and the flux is 47.7L / m 2 ·h.

[0016] (2) The base membrane used in (1) is improved by in situ growing ZIF-8 in the base membrane. The porosity of ZIF-8 is used to give the membrane water channels. The stacked ZIF-8 enhances the pore size screening effect of the membrane, so that the membrane maintains a good iodide ion removal rate in solutions containing chloride ions or acid ions, and the anti-protein adsorption ability is enhanced. The flux recovery rates of the membrane prepared under the optimized conditions after three cycles in bovine serum albumin solution or lysozyme solution are 92.4% and 81.7%, respectively, which is about 20% higher than that of the simply grafted sample.

[0017] (3) The base membrane used in (1) was improved by introducing Ag / Ag2O during the growth of ZIF-8 and the subsequent irradiation process, and the removal rate of iodide ions by the membrane was further improved by adsorption. The removal rate of iodide ions by the membrane prepared under the optimized conditions reached 96.3%, and the removal rate was maintained above 95% in solutions containing chloride ions and sulfate ions. Similarly, the flux recovery rate of the membrane after three cycles in bovine serum albumin solution or lysozyme solution was about 20% higher than that of the simply grafted sample.

[0018] Unlike the reverse osmosis membrane TFC-HR commonly used for iodine ion removal, the present invention can achieve a high iodine ion removal rate with a larger pore size due to enhanced charge repulsion, and the flux is at least 10 times greater than that of TFC-HR.

[0019] The present invention is based on improving the charge repulsion effect on the membrane surface, and constructs a high-flux nanofiltration membrane suitable for separating monovalent iodide ions. The nanofiltration membrane uses a UV-sensitive polysulfone ultrafiltration membrane or a modified membrane thereof as a base membrane, sodium styrene sulfonate as a grafting monomer, ZIF-8 or Ag / Ag2O@ZIF-8 as a modifier, and is prepared by an ultraviolet irradiation grafting method. The structure and performance of the nanofiltration membrane can be conveniently adjusted by adjusting the base membrane properties, irradiation power, irradiation distance, irradiation time, monomer concentration, type and content of the modifier, etc. The nanofiltration membrane disclosed by the present invention has a high iodine ion removal rate, a low operating pressure, and a large flux. The solvent used in the preparation process is water, which is green and environmentally friendly, and is suitable for the removal of iodine ions from wastewater containing radioactive iodine ions and waters with high iodine ion content, and has good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Surface morphology diagrams of Example 1 (A) and Example 9 (B). DETAILED DESCRIPTION

[0021] The present invention uses ultrafiltration membrane as base membrane, ethylene derivatives as monomers for preparing membrane, porous MOF materials as modifiers, and is prepared by ultraviolet irradiation grafting method. The structure and performance of the nanofiltration membrane can be conveniently adjusted by adjusting the base membrane properties, irradiation power, irradiation intensity, irradiation distance, irradiation time, monomer concentration, dopant type and content, etc.

[0022] The ultrafiltration membrane used in the present invention is a UV-sensitive polysulfone ultrafiltration membrane or a modified polysulfone ultrafiltration membrane, and the molecular weight cut-off is less than or equal to 50,000;

[0023] The ethylene derivative used in the present invention is sodium styrene sulfonate;

[0024] The porous MOF material of the present invention is ZIF-8 or Ag / Ag2O@ZIF-8.

[0025] The separation performance of the nanofiltration membrane prepared by the present invention is tested by a cross-flow membrane evaluation instrument, a conductivity meter, and a UV-visible spectrophotometer. The test temperature is room temperature and the test pressure is 0.6 MPa. The osmotic pressure of the membrane is characterized by the solution flux F of the membrane under this condition (unit, L / m 2 .h); The selective permeability of the membrane was 100mg / LI - , containing 100mg / L Cl - and 100mg / L - Mixed solution, containing 100mg / L SO4 2- and 100mg / L - The removal rate R of iodine ions in the mixed solution is used to characterize it; the membrane is used to filter bovine serum albumin or lysozyme protein solution, respectively, and then the membrane surface is cleaned. The water flux after cleaning is compared with the water flux before the membrane filters the protein, and the flux recovery rate FRR after three cycles is calculated to evaluate the membrane's anti-protein adsorption ability.

[0026] Example 1

[0027] The base membrane used in this example is a polysulfone ultrafiltration membrane with a molecular weight cutoff of 30,000. The grafted monomer is sodium styrene sulfonate, and the porous MOF material is ZIF-8. The specific preparation steps are as follows:

[0028] 1) First, a polysulfone ultrafiltration membrane with a molecular weight cutoff of 30,000 was fixed in the middle of a 15×15 cm container.

[0029] 2) Add 200 mL of 0.0245 mol / L Zn(NO3)2 aqueous solution to the front side of the polysulfone ultrafiltration membrane, and add 130 mL of 0.1956 mol / L 2-methylimidazole (2-mIm) aqueous solution to the back side. The reactants diffuse with each other for 6 hours, and then wash with deionized water to obtain ZIF-8 modified polysulfone ultrafiltration membrane.

[0030] 3) The ZIF-8 modified polysulfone ultrafiltration membrane was placed in a UV grafting mold, 40 mL of 0.5 mol / L sodium styrene sulfonate (SS) solution was added to the surface, and then placed under a 300 W UV lamp for 4 cm and irradiated for 15 min. Finally, the membrane was taken out of the mold and repeatedly washed with deionized water to remove the residual monomer and homopolymer to obtain product 1.

[0031] Example 2

[0032] 1) First, a polysulfone ultrafiltration membrane with a molecular weight cutoff of 30,000 was fixed in the middle of a 15×15 cm container.

[0033] 2) Add 200 mL of 0.0125 mol / L Zn(NO3)2 aqueous solution to the front side of the polysulfone ultrafiltration membrane, and add 130 mL of 0.1956 mol / L 2-methylimidazole (2-mIm) aqueous solution to the back side. The reactants diffuse with each other for 6 hours, and then wash with deionized water to obtain ZIF-8 modified polysulfone ultrafiltration membrane.

[0034] 3) The ZIF-8 modified polysulfone ultrafiltration membrane was placed in a UV grafting mold, 40 mL of 0.5 mol / L sodium styrene sulfonate (SS) solution was added to the surface, and then placed 4 cm under a 300 W UV lamp for irradiation grafting for 15 min. Finally, the membrane was removed from the mold and repeatedly washed with deionized water to remove residual monomers and homopolymers to obtain product 2.

[0035] Example 3

[0036] 1) First, a polysulfone ultrafiltration membrane with a molecular weight cutoff of 30,000 was fixed in the middle of a 15×15 cm container.

[0037] 2) Add 200 mL of 0.0245 mol / L Zn(NO3)2 aqueous solution to the front side of the polysulfone ultrafiltration membrane, and add 130 mL of 0.1956 mol / L 2-methylimidazole (2-mIm) aqueous solution to the back side. The reactants diffuse with each other for 3 hours, and then wash with deionized water to obtain ZIF-8 modified polysulfone ultrafiltration membrane.

[0038] 3) The ZIF-8 modified polysulfone ultrafiltration membrane was placed in a UV grafting mold, 40 mL of 0.5 mol / L sodium styrene sulfonate (SS) solution was added to the surface, and then placed under a 300 W UV lamp for 4 cm and irradiated for grafting for 15 min. Finally, the membrane was removed from the mold and repeatedly washed with deionized water to remove residual monomers and homopolymers to obtain product 3.

[0039] Example 4

[0040] 1) First, a polysulfone ultrafiltration membrane with a molecular weight cutoff of 30,000 was fixed in the middle of a 15×15 cm container.

[0041] 2) Add 200 mL of 0.0245 mol / L Zn(NO3)2 aqueous solution to the front side of the polysulfone ultrafiltration membrane, and add 130 mL of 0.1956 mol / L 2-methylimidazole (2-mIm) aqueous solution to the back side. The reactants diffuse with each other for 24 hours, and then wash with deionized water to obtain ZIF-8 modified polysulfone ultrafiltration membrane.

[0042] 3) The ZIF-8 modified polysulfone ultrafiltration membrane was placed in a UV grafting mold, 40 mL of 0.5 mol / L sodium styrene sulfonate (SS) solution was added to the surface, and then placed 4 cm under a 300 W UV lamp for irradiation grafting for 15 min. Finally, the membrane was removed from the mold and repeatedly washed with deionized water to remove residual monomers and homopolymers to obtain product 4.

[0043] Example 5

[0044] 1) First, a polysulfone ultrafiltration membrane with a molecular weight cutoff of 30,000 is fixed in the middle of a 15×15 cm container.

[0045] 2) Add 200 mL of 0.0159 mol / L Zn(NO3)2 aqueous solution to the front side of the polysulfone ultrafiltration membrane, and add 130 mL of 0.1956 mol / L 2-methylimidazole (2-mIm) aqueous solution to the back side. The reactants diffuse with each other for 6 hours, and then wash with deionized water to obtain ZIF-8 modified polysulfone ultrafiltration membrane.

[0046] 3) The ZIF-8 modified polysulfone ultrafiltration membrane was placed in a UV grafting mold, 40 mL of 0.5 mol / L sodium styrene sulfonate (SS) solution was added to the surface, and then placed under a 300 W UV lamp at a depth of 4 cm for irradiation grafting for 15 min. Finally, the membrane was removed from the mold and repeatedly washed with deionized water to remove residual monomers and homopolymers to obtain product 5.

[0047] Example 6

[0048] 1) First, a polysulfone ultrafiltration membrane with a molecular weight cutoff of 30,000 is fixed in the middle of a 15×15 cm container.

[0049] 2) Add 200 mL of 0.0613 mol / L Zn(NO3)2 aqueous solution to the front side of the polysulfone ultrafiltration membrane, and add 130 mL of 0.4890 mol / L 2-methylimidazole (2-mIm) aqueous solution to the back side. The reactants diffuse with each other for 6 hours, and then wash with deionized water to obtain ZIF-8 modified polysulfone ultrafiltration membrane.

[0050] 3) The ZIF-8 modified polysulfone ultrafiltration membrane was placed in a UV grafting mold, 40 mL of 0.5 mol / L sodium styrene sulfonate (SS) solution was added to the surface, and then placed 4 cm under a 300 W UV lamp for irradiation grafting for 15 min. Finally, the membrane was removed from the mold and repeatedly washed with deionized water to remove residual monomers and homopolymers to obtain product 6.

[0051] Example 7

[0052] First, a polysulfone ultrafiltration membrane of a certain size was cut and fixed in a UV grafting mold. Then, 40 mL of 1.0 mol / L sodium styrene sulfonate (SS) solution was added into the mold. The mold was then placed 7 cm below a 300 W UV lamp and irradiated for 15 min. Finally, the membrane was removed from the mold and repeatedly washed with deionized water to remove residual monomers and homopolymers to obtain product 7.

[0053] Example 8

[0054] First, a polysulfone ultrafiltration membrane of a certain size was cut and fixed in a UV grafting mold. Then, 40 mL of 0.5 mol / L sodium styrene sulfonate (SS) solution was added into the mold. The mold was then placed 4 cm below a 300 W UV lamp and irradiated for 15 min. Finally, the membrane was removed from the mold and repeatedly washed with deionized water to remove residual monomers and homopolymers to obtain product 8.

[0055] Example 9

[0056] 1) First, fix the polysulfone ultrafiltration membrane with a molecular weight cutoff of 30,000 in the middle of a 15×15 cm container

[0057] 2) Add 200mL of a mixed solution of 0.0245mol / L Zn(NO3)2 and 0.0117mol / L AgNO3 to the front side of the polysulfone ultrafiltration membrane, and add 130mL of 0.1956 mol / L 2-methylimidazole (2-mIm) aqueous solution to the reverse side of the membrane. The reactants diffuse with each other for 6 hours, and then wash with deionized water to obtain Ag / Ag2O@ZIF-8 modified polysulfone ultrafiltration membrane. Note that some Ag / Ag2O is generated during the irradiation process.

[0058] 3) The Ag / Ag2O@ZIF-8 modified polysulfone ultrafiltration membrane was placed in a UV grafting mold, 40 mL of 0.5 mol / L sodium styrene sulfonate (SS) solution was added to the surface, and then placed under a 300 W UV lamp for 4 cm and irradiated for 15 min. Finally, the membrane was removed from the mold and repeatedly washed with deionized water to remove residual monomers and homopolymers to obtain product 9.

[0059] Example 10

[0060] 1) First, a polysulfone ultrafiltration membrane with a molecular weight cutoff of 50,000 is fixed in the middle of a 15×15 cm container.

[0061] 2) Add 200mL of a mixed solution of 0.0245mol / L Zn(NO3)2 and 0.0039mol / LAgNO3 to the front side of the polysulfone ultrafiltration membrane, and add 130mL of 0.1956 mol / L 2-methylimidazole (2-mIm) aqueous solution to the reverse side of the membrane. The reactants diffuse with each other for 12h, and then wash with deionized water to obtain Ag / Ag2O@ZIF-8 modified polysulfone ultrafiltration membrane.

[0062] 3) The Ag / Ag2O@ZIF-8 modified polysulfone ultrafiltration membrane was placed in a UV grafting mold, 40 mL of 0.5 mol / L sodium styrene sulfonate (SS) solution was added to the surface, and then placed under a 300 W UV lamp at a distance of 7 cm for irradiation grafting for 15 min. Finally, the membrane was removed from the mold and repeatedly washed with deionized water to remove residual monomers and homopolymers to obtain product 10.

[0063] Embodiment 11

[0064] 1) First, a polysulfone ultrafiltration membrane with a molecular weight cutoff of 50,000 is fixed in the middle of a 15×15 cm container.

[0065] 2) Add 200mL of a mixed solution of 0.0245mol / L Zn(NO3)2 and 0.0117mol / L AgNO3 to the front side of the polysulfone ultrafiltration membrane, and add 130mL of 0.1956 mol / L 2-methylimidazole (2-mIm) aqueous solution to the reverse side of the membrane. The reactants diffuse with each other for 6 hours, and then wash with deionized water to obtain Ag / Ag2O@ZIF-8 modified polysulfone ultrafiltration membrane. Note that some Ag / Ag2O is generated during the irradiation process.

[0066] 3) The Ag / Ag2O@ZIF-8 modified polysulfone ultrafiltration membrane was placed in a UV grafting mold, 40 mL of 1 mol / L sodium styrene sulfonate (SS) solution was added to the surface, and then placed 7 cm under a 300 W UV lamp for irradiation grafting for 15 min. Finally, the membrane was removed from the mold and repeatedly washed with deionized water to remove residual monomers and homopolymers to obtain product 11.

[0067] The separation performance and anti-protein adsorption capacity of the nanofiltration membranes obtained in the above examples are shown in Table 1. The surface morphologies of the base membrane, the nanofiltration membranes prepared in Example 1 and Example 9 are shown in Table Figure 1 .

[0068] Table 1 Separation performance of the nanofiltration membrane obtained in the embodiment

[0069]

[0070] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A high flux nanofiltration membrane suitable for iodide ion separation, characterized in that: The ultrafiltration membrane is prepared by using an ultrafiltration membrane or an ultrafiltration membrane modified by a porous MOF material as a base membrane and ethylene derivatives as membrane-making monomers through an ultraviolet radiation grafting method.

2. The high flux nanofiltration membrane suitable for iodide ion separation according to claim 1, characterized in that: The ultrafiltration membrane is a polysulfone ultrafiltration membrane or a porous MOF material modified polysulfone ultrafiltration membrane.

3. The high flux nanofiltration membrane suitable for iodide ion separation according to claim 1, characterized in that: The ethylene derivative is sodium styrene sulfonate.

4. The high flux nanofiltration membrane suitable for iodide ion separation according to claim 1, characterized in that: The porous MOF material is ZIF-8 or Ag / Ag2O@ZIF-8.

5. A method for preparing a high-flux nanofiltration membrane suitable for iodide ion separation, characterized in that: A vinyl derivative solution is added to a polysulfone ultrafiltration membrane or a porous MOF material modified polysulfone ultrafiltration membrane, and the membrane is subjected to in-situ irradiation grafting and heat treatment for a period of time, followed by cooling and washing.

6. The method for preparing a high-flux nanofiltration membrane suitable for iodide ion separation according to claim 5, characterized in that: The preparation process of the porous MOF material modified polysulfone ultrafiltration membrane is as follows: fix the polysulfone ultrafiltration membrane in the middle of a container; first add 0.0159-0.0613 mol / L Zn(NO3)2 aqueous solution to the front side of the polysulfone ultrafiltration membrane, and then add 0.1956-0.4890 mol / L 2-methylimidazole aqueous solution to the back side, the reactants diffuse with each other, the reaction time is 3-24 hours, and then wash with deionized water to obtain a ZIF-8 modified polysulfone ultrafiltration membrane.

7. The method for preparing a high-flux nanofiltration membrane suitable for iodine ion separation according to claim 5, characterized in that: The preparation process of the porous MOF material modified polysulfone ultrafiltration membrane is as follows: first, the polysulfone ultrafiltration membrane is fixed in the middle of a container; a mixed solution of Zn(NO3)2 and AgNO3 is prepared, and the concentrations in the mixed solution are: 0.0159-0.0613 mol / L Zn(NO3)2, 0.0039-0.0117 mol / L AgNO3, the mixed solution is first added to the front side of the polysulfone ultrafiltration membrane, and then 0.1956-0.4890 mol / L 2-methylimidazole aqueous solution is added to the back side, the reactants diffuse with each other, the reaction time is 3-24 hours, and then washed with deionized water to obtain Ag / Ag2O@ZIF-8 modified polysulfone ultrafiltration membrane.

8. The method for preparing a high-flux nanofiltration membrane suitable for iodide ion separation according to claim 5, characterized in that: The ethylene derivative solution is a sodium styrene sulfonate solution. A polysulfone ultrafiltration membrane or a ZIF-8 modified polysulfone ultrafiltration membrane or an Ag / Ag2O@ZIF-8 modified polysulfone ultrafiltration membrane is placed in an ultraviolet grafting mold, 40 mL of a 0.5-1.0 mol / L sodium styrene sulfonate solution is added to the surface, and then the membrane is placed under an ultraviolet lamp for irradiation grafting. Finally, the rear membrane is taken out from the ultraviolet grafting mold, and is repeatedly washed with deionized water to remove residual monomers and homopolymers, thereby obtaining a high-flux nanofiltration membrane.

9. Use of the high-flux nanofiltration membrane according to claim 1 in iodide ion separation.

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