Sulfonated porous polymer nanoparticle-metal organic framework composite cation exchange membrane and preparation method thereof

Abstract

The invention discloses a sulfonated porous polymer nanoparticle-metal organic framework composite cation exchange membrane and a preparation method thereof. With porous polymer nanoparticles and aminosulfonate as raw materials and dopamine as a biomimetic adhesive, sulfonation of porous polymer nanoparticles is achieved by oxidative polymerization in an aqueous solution, and a composite cation exchange membrane is prepared by pressure filtration, surface assembly and in-situ growth on the surface of a porous support membrane. The membrane combines the advantages of polymer porous materials and metal organic framework materials, and the chemical composition and pore structure are easy to regulate. The membrane has a high lithium ion flux and a high magnesium-lithium permeation separation selectivity. The membrane contains a dopamine component, so that stable coordination bonds or covalent bonds can be formed between the polymer nanoparticles in the membrane, and between the polymer nanoparticles and the metal organic framework material and the porous support membrane, so that the membrane has both high ion permeation selectivity and good structural stability, and will have good application prospects in the field of lithium extraction from salt lake brine or separation of single and multivalent cations.

Description

Technical Field

[0001] The invention belongs to the field of selective electrodialysis membrane separation, and in particular relates to a high-flux and high-selectivity sulfonated porous polymer nanoparticle-metal organic framework composite cation exchange membrane and a preparation method thereof. Background Art

[0002] As the lightest metal found in nature, lithium metal has become one of the most important resources. It is widely used in new energy, aerospace, glass ceramics, biopharmaceuticals and other fields. In recent years, lithium batteries have been favored by electric vehicle companies because of their light weight, high energy density and high electrochemical potential (3.04V). The steady growth of lithium batteries around the world has led to a sharp expansion in lithium battery production in recent years, and the demand for lithium resources has also increased. Lithium resources are mainly stored in lithium ore, seawater and salt lake water. At present, the main methods for extracting lithium from salt lakes include precipitation, adsorption, extraction, electrochemical and membrane methods. Among them, electrodialysis membrane technology has the advantages of high separation efficiency, low energy consumption and environmental friendliness, and has become an important technical development direction for extracting lithium from salt lakes in the future.

[0003] Selective cation exchange membranes can separate lithium from coexisting ions with similar physical and chemical properties. Although commercial ion exchange membranes have high ion permeability, their separation selectivity for monovalent and divalent ions is low. The preparation of existing monovalent and divalent cation selective exchange membranes mostly adopts membrane surface modification methods, including electrostatic adsorption, electrodeposition, layer-by-layer self-assembly, surface grafting and other methods. Yu et al. prepared a monovalent and multivalent cation selective exchange membrane on the surface of a polyacrylate-based membrane by layer-by-layer self-assembly of polystyrene sulfonate and polyethyleneimine. The membrane is selective for Mg 2+ / Li + The ion separation selectivity is 4.59, but the interaction between the modified layer and the supporting layer is weak and easy to fall off, and the membrane stability is poor (Chemical Engineering Journal, 2022, 446, 137076). Patent CN105107393A discloses a method for preparing a mono-polyvalent ion selective exchange membrane based on a template method, by repeatedly immersing the base membrane in a polycationic / anionic electrolyte aqueous solution containing template ions, forming a certain self-assembled layer on the surface of the ion membrane, and then immersing the self-assembled composite membrane in a cross-linking agent solution, and finally obtaining a mono-polyvalent ion selective composite membrane, which has good separation selectivity, but its permeability to monovalent ions is low.

[0004] Biological nerve cells contain special potassium ion channel structures that can achieve efficient and selective potassium ion transmission. Inspired by the above biological ion channel structure, researchers have achieved rapid ion transmission in membrane channels by constructing special ion channel structures in separation membranes and fixing different functional groups such as sulfonic acid groups and phosphate groups in their channels. Zhang et al. prepared a UiO-67 membrane on anodized aluminum oxide (AAO) membrane modified with polyvinyl pyrrolidone (PVP) by a washing-assisted secondary growth method, with a lithium ion permeability of up to 27 mol·m -2 ·h -1 , Li + / Mg 2+ The separation selectivity is 159 (Angewandte Chemie, 2022, 61, e202115443. Xu et al. placed two monomers on both sides of the bottom membrane and prepared a porous organic cage membrane by the reverse diffusion method. The discontinuous internal pores and the external pores connected by sub-nanometer-sized windows were used to achieve efficient transport of monovalent ions in the membrane. Due to the difference in the permeation energy barrier between monovalent and multivalent ions, the membrane is very suitable for K + / Mg 2+ It has high separation selectivity (Journal of the American Chemical Society, 2022, 144, 23, 10220-10229). Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a sulfonated porous polymer nanoparticle-metal organic framework composite cation exchange membrane and a preparation method. Using porous polymer nanoparticles and aminosulfonate as raw materials and dopamine as a biomimetic adhesive, oxidative polymerization in an aqueous solution realizes the sulfonation of porous polymer nanoparticles, and pressure filtration, surface assembly and in-situ growth methods are used on the surface of the porous support membrane to prepare a sulfonated porous polymer nanoparticle-metal organic framework composite cation exchange membrane. The composite nano separation layer constructed by the above method combines the advantages of polymer porous materials and metal organic framework materials, and its chemical composition and pore structure are easy to control, so that the membrane has high ion permeability and separation selectivity. At the same time, the sulfonated porous polymer nanoparticles contain dopamine components, and stable coordination bonds or covalent bonds can be formed between the polymer nanoparticles, and between the polymer nanoparticles and the metal organic framework material and the porous support membrane, so that the membrane has both high ion permeability selectivity and good structural stability, and will have good application prospects in the field of lithium extraction from salt lake brine or single multivalent cation separation.

[0006] The technical solution adopted by the present invention is specifically as follows:

[0007] A method for preparing a sulfonated porous polymer nanoparticle-metal organic framework composite cation exchange membrane comprises the following steps:

[0008] 1) adding 0.05-1.0 parts by weight of a triazine derivative to 25-500 parts by weight of an acetic acid aqueous solution, and adding 0.2-1.2 parts by weight of a 1,2-dicarbonyl compound and 0.05-0.6 parts by weight of an aldehyde compound to the above solution after dissolution, and reacting at 60-120° C. for 12-72 hours to obtain a triazine porous polymer nanoparticle dispersion, dispersing 0.3-1.5 parts by weight of the above triazine porous polymer nanoparticle dispersion, 0.15-0.90 parts by weight of aminosulfonate and 0.05-0.25 parts by weight of dopamine hydrochloride in 1000 parts by weight of an alkaline aqueous solution, and reacting under magnetic stirring to obtain an aqueous dispersion of sulfonated porous polymer nanoparticles;

[0009] 2) dispersing 5 to 20 parts by weight of a metal acid salt and 2 to 10 parts by weight of an organic amine in 1000 parts by weight of deionized water, stirring the mixture by magnetic force and standing the mixture for 10 to 50 minutes to obtain a metal nanowire aqueous dispersion, filtering 100 to 500 parts by weight of the sulfonated porous polymer nanoparticle aqueous dispersion on the surface of a porous support membrane, and then filtering 5 to 25 parts by weight of the metal nanowire aqueous dispersion to form a sulfonated porous polymer nanoparticle-metal nanowire composite membrane;

[0010] 3) impregnating the surface of the sulfonated porous polymer nanoparticle-metal nanowire composite membrane with an organic ligand solution to prepare a metal organic framework material by in-situ growth on the surface, washing with ethanol-water, and airing at 15-35° C. for 2-6 hours to obtain a sulfonated porous polymer nanoparticle-metal organic framework composite cation exchange membrane;

[0011] The triazine derivatives described in step 1) are one or more of 2,4-diamino-1,3,5-triazine, 4,6-diamino-2-hydroxy-1,3,5-triazine, 2,4-diamino-[N,N'-di(4'-p-aminobenzylbenzene)]-6-phenyl-1,3,5-triazine, and 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, mixed in any proportion; the 1,2-dicarbonyl compound described in step 1) is one or more of methylglyoxal, glyoxal, 1,2-cyclohexanedione, diphenylethanedione, and 1,4-di(phenylethanediyl)benzene, mixed in any proportion; the aldehyde compound described in step 1) is formaldehyde, propionaldehyde, benzaldehyde, propionaldehyde One or more of olefinic aldehyde and terephthalaldehyde are mixed in any proportion; the aminosulfonate described in step 1) is one of sodium 2,4-diaminobenzenesulfonate or sodium p-aminobenzenesulfonate; the metal acid salt described in step 2) is one of zinc nitrate, zinc acetate, ferric chloride, copper nitrate, cobalt nitrate, and cobalt acetate. Mixed in any proportion; the organic amine described in step 2) is one of ethanolamine, ethylenediamine, and triethylamine. Mixed in any proportion; the porous support membrane described in step 2) is one of polyvinylidene fluoride, polysulfone, or sulfonated polysulfone; the organic ligand described in step 3) is one of 2-methylimidazole, benzimidazole, and trimesic acid. Mixed in any proportion.

[0012] Preferably, the mass percentage concentration of the acetic acid aqueous solution described in step 1) is 10-50%; the alkaline aqueous solution described in step 1) is a sodium hydroxide or potassium hydroxide aqueous solution with a mass percentage concentration of 0.01-0.1%; the reaction conditions under magnetic stirring described in step 1) are 15-35°C and 500-1500 rpm magnetic stirring for 1-3 hours; the magnetic stirring conditions described in step 2) are 800-1500 rpm magnetic stirring at 15-35°C for 5-10 minutes; the filtering conditions on the surface of the porous support membrane described in step 2) are filtration at an operating pressure of 0.05-0.10MPa for 1-3 hours; the mass percentage concentration of the organic ligand solution described in step 3) is 0.4-4%; the solvent of the organic ligand solution described in step 3) is water, methanol or ethanol; the immersion treatment conditions of the organic ligand solution described in step 3) are immersion at 15-35°C for 0.5-6 hours.

[0013] A sulfonated porous polymer nanoparticle-metal organic framework composite cation exchange membrane prepared by the above preparation method can be used in the field of separation of metal cations with different valence states.

[0014] Sulfonated porous polymer nanoparticles-metal organic framework composite cation exchange membrane is made of porous polymer nanoparticles and aminosulfonate as raw materials, dopamine as biomimetic binder, oxidative polymerization in aqueous solution to achieve sulfonation of porous polymer nanoparticles, and pressure filtration, surface assembly and in situ growth methods are used on the surface of the porous support membrane to prepare the sulfonated porous polymer nanoparticles-metal organic framework composite cation exchange membrane. The composite nano separation layer constructed by the above method combines the advantages of polymer porous materials and metal organic framework materials, and its chemical composition and pore structure are easy to control. The lithium ion flux of the obtained sulfonated porous nanoparticles-metal organic framework composite membrane is as high as 6-11 mol·m -2 ·h -1 , the magnesium-lithium permeation separation selectivity is 5 to 32. At the same time, the sulfonated porous polymer nanoparticles contain dopamine components, and stable coordination bonds or covalent bonds can be formed between the polymer nanoparticles and between the polymer nanoparticles and the metal organic framework material and the porous support membrane, so that the membrane has both high ion permeation selectivity and good structural stability, and will have good application prospects in the field of lithium extraction from salt lake brine or separation of monovalent and polyvalent cations. DETAILED DESCRIPTION

[0015] A method for preparing a sulfonated porous polymer nanoparticle-metal organic framework composite cation exchange membrane comprises the following steps:

[0016] 1) adding 0.05-1.0 parts by weight of a triazine derivative to 25-500 parts by weight of an acetic acid aqueous solution, and adding 0.2-1.2 parts by weight of a 1,2-dicarbonyl compound and 0.05-0.6 parts by weight of an aldehyde compound to the above solution after dissolution, and reacting at 60-120° C. for 12-72 hours to obtain a triazine porous polymer nanoparticle dispersion, dispersing 0.3-1.5 parts by weight of the above triazine porous polymer nanoparticle dispersion, 0.15-0.90 parts by weight of aminosulfonate and 0.05-0.25 parts by weight of dopamine hydrochloride in 1000 parts by weight of an alkaline aqueous solution, and reacting under magnetic stirring to obtain an aqueous dispersion of sulfonated porous polymer nanoparticles;

[0017] 2) dispersing 5 to 20 parts by weight of a metal acid salt and 2 to 10 parts by weight of an organic amine in 1000 parts by weight of deionized water, stirring the mixture by magnetic force and standing the mixture for 10 to 50 minutes to obtain a metal nanowire aqueous dispersion, filtering 100 to 500 parts by weight of the sulfonated porous polymer nanoparticle aqueous dispersion on the surface of a porous support membrane, and then filtering 5 to 25 parts by weight of the metal nanowire aqueous dispersion to form a sulfonated porous polymer nanoparticle-metal nanowire composite membrane;

[0018] 3) impregnating the surface of the sulfonated porous polymer nanoparticle-metal nanowire composite membrane with an organic ligand solution to prepare a metal organic framework material by in-situ growth on the surface, washing with ethanol-water, and airing at 15-35° C. for 2-6 hours to obtain a sulfonated porous polymer nanoparticle-metal organic framework composite cation exchange membrane;

[0019] The triazine derivatives described in step 1) are one or more of 2,4-diamino-1,3,5-triazine, 4,6-diamino-2-hydroxy-1,3,5-triazine, 2,4-diamino-[N,N'-di(4'-p-aminobenzylbenzene)]-6-phenyl-1,3,5-triazine, and 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, mixed in any proportion; the 1,2-dicarbonyl compound described in step 1) is one or more of methylglyoxal, glyoxal, 1,2-cyclohexanedione, diphenylethanedione, and 1,4-di(phenylethanediyl)benzene. The aldehyde compound in step 1) is one or more of formaldehyde, propionaldehyde, benzaldehyde, acrolein, and terephthalaldehyde mixed in any proportion; the aminosulfonate in step 1) is one or more of sodium 2,4-diaminobenzenesulfonate and sodium p-aminobenzenesulfonate mixed in any proportion; the metal acid salt in step 2) is one or more of zinc nitrate, zinc acetate, ferric chloride, copper nitrate, cobalt nitrate, and cobalt acetate mixed in any proportion; the organic amine in step 2) is one or more of ethanolamine, ethylenediamine, and triethylamine mixed in any proportion The porous support membrane in step 2) is one of polyvinylidene fluoride, polysulfone or sulfonated polysulfone; the organic ligand in step 3) is one of 2-methylimidazole, benzimidazole and trimesic acid mixed in any proportion; the mass percentage concentration of the acetic acid aqueous solution in step 1) is 10-50%; the alkaline aqueous solution in step 1) is a sodium hydroxide or potassium hydroxide aqueous solution with a mass percentage concentration of 0.01-0.1%; the reaction conditions under magnetic stirring in step 1) are 15-35°C and 500-1500 rpm magnetic stirring The reaction is stirred for 1 to 3 hours; the magnetic stirring condition described in step 2) is 800 to 1500 rpm at 15 to 35° C. and magnetic stirring for 5 to 10 minutes; the filtering condition on the surface of the porous support membrane described in step 2) is filtering at an operating pressure of 0.05 to 0.10 MPa for 1 to 3 hours; the mass percentage concentration of the organic ligand solution described in step 3) is 0.4 to 4%; the solvent of the organic ligand solution described in step 3) is water, methanol or ethanol; the immersion treatment condition of the organic ligand solution described in step 3) is immersion at 15 to 35° C. for 0.5 to 6 hours.

[0020] Embodiments of the present invention are given below, but the present invention is not limited by the embodiments;

[0021] In the following examples, the separation performance test method of the sulfonated porous polymer nanoparticle-metal organic framework composite cation exchange membrane is as follows: the above cation exchange membrane is placed in an electrodialysis test device in the art, and the desalination chamber is 100 mL of 0.1 mol·L -1 LiCl and 0.1 mol·L -1 MgCl2 solution, the concentration chamber is 100mL of 0.01mol·L -1 KCl solution, 300 mL of 0.3 mol·L in both electrode compartments -1 Na2SO4 solution. After 1 hour of electrodialysis test, a certain solution was taken out from the concentration chamber to test its cation concentration. The membrane sample was pre-balanced in the test solution for 24 hours and thoroughly cleaned before measurement. The performance of each membrane sample was repeated at least three times to take the average value. The ion permeation flux (J) and permeation selectivity (P) of the membrane are calculated as follows: J N n+ =(C t -C0)·V / (A e ·t), P Li + / Mg 2+ =(J Li + ·C Mg 2+ ) / (J Mg 2+ ·C Li + ), where J N n+ is the amount of cations permeating through the membrane (mol·m -2 ·h -1 ), C t and C0(mol·L -1 ) are the cation concentrations at the end and the beginning of the electrodialysis test (N n + ), V is the volume of the solution in the concentrating chamber, A e is the effective area of ​​the membrane; J Li + and J Mg 2+ (mol·m -2 ·h -1 ) is the Li permeating the membrane after the test + and Mg 2+ The flux, C Li + and C Mg 2+ (mol·L -1 ) are respectively the Li +and Mg 2+ The average concentration of the metal salt solution was measured by plasma emission spectrometry.

[0022] Embodiment 1:

[0023] 0.05 g of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine was added to 25 g of 10 wt% acetic acid aqueous solution, and after dissolution, 0.2 g of acetone aldehyde and 0.05 g of formaldehyde were added to the above solution, and the mixture was reacted at 60° C. for 12 hours to obtain a triazine porous polymer nanoparticle dispersion. 0.3 g of the above triazine porous polymer nanoparticle dispersion and 0.15 g of Sodium 2,4-diaminobenzenesulfonate and 0.05 g of dopamine hydrochloride were dispersed in 1000 g of sodium hydroxide alkaline aqueous solution with a pH of 10, and reacted at 15° C. and 500 rpm for 1 hour to obtain an aqueous dispersion of sulfonated porous polymer nanoparticles; 5 g of zinc nitrate hexahydrate and 2 g of ethanolamine were dispersed in 1000 g of deionized water, magnetically stirred at 15° C. and 800 rpm for 5 minutes, and allowed to stand for 10 minutes to obtain an aqueous solution of metal nanowires; 100 g of the above aqueous dispersion of sulfonated porous polymer nanoparticles was added to polyvinylidene fluoride microparticles. The membrane surface was filtered, and then 5 g of the metal nanowire aqueous dispersion was vacuum filtered at 0.05 MPa for 1 hour to obtain a sulfonated nanoparticle-metal nanowire composite membrane; a 0.4% by mass 2-methylimidazole ethanol solution was immersed on the surface of the sulfonated porous polymer nanoparticle-metal nanowire composite membrane at 15°C for 0.5 hour to prepare a metal organic framework material by in situ growth on the surface; after washing with ethanol-water, the membrane was left to air at 15°C for 2 hours to obtain a sulfonated porous polymer nanoparticle-metal organic framework composite cation exchange membrane.

[0024] Sulfonated porous polymer nanoparticles-metal organic framework composite cation exchange membrane at 25℃, 5mA·cm -2 Under electric field, the -1 LiCl and 0.1 mol·L -1 The separation results of the MgCl2 mixed liquid are as follows: the lithium ion flux is 8.9 mol·m -2 ·h -1 , the magnesium ion flux is 0.5 mol·m -2 ·h -1 , the magnesium-lithium ion permeation selectivity is 16.5.

[0025] Embodiment 2:

[0026] 1.0 g of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine was added to 500 g of 50 wt% acetic acid aqueous solution, and after dissolution, 1.2 g of acetone aldehyde and 0.6 g of formaldehyde were added to the above solution, and the mixture was reacted at 120° C. for 72 hours to obtain a triazine porous polymer nanoparticle dispersion. 1.5 g of the above triazine porous polymer nanoparticle dispersion and 0.90 g of Sodium 2,4-diaminobenzenesulfonate and 0.25g dopamine hydrochloride were dispersed in 1000g of sodium hydroxide alkaline aqueous solution with a pH of 10, and reacted at 35°C and 1500 rpm for 3 hours to obtain an aqueous dispersion of sulfonated porous polymer nanoparticles; 20g zinc nitrate hexahydrate and 10g ethanolamine were dispersed in 1000g deionized water, magnetically stirred at 35°C and 1500 rpm for 10 minutes, and allowed to stand for 50 minutes to obtain a metal nanowire aqueous solution; 500g of the above sulfonated porous polymer nanoparticle aqueous dispersion was added to a polyisocyanate solution and stirred for 10 minutes. The sulfonated porous polymer nanoparticle-metal nanowire composite membrane was immersed in 4% 2-methylimidazole ethanol solution at 35°C for 6 hours to prepare the metal organic framework material by in situ growth on the surface. After washing with ethanol-water, the membrane was left to stand at 35°C for 6 hours to obtain the sulfonated porous polymer nanoparticle-metal organic framework composite cation exchange membrane.

[0027] Sulfonated porous nanoparticle-metal organic framework composite membrane at 25℃, 5mA·cm -2 Under electric field, the -1 LiCl and 0.1 mol·L -1 The separation results of the MgCl2 mixed liquid are as follows: the lithium ion flux is 7.6 mol·m -2 ·h -1 , the magnesium ion flux is 0.4 mol·m -2 ·h -1 , the magnesium-lithium ion permeation selectivity is 17.4.

[0028] Embodiment 3:

[0029] 0.5 g of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine was added to 250 g of 25 wt% acetic acid aqueous solution, and after dissolution, 0.5 g of acetone aldehyde and 0.3 g of formaldehyde were added to the above solution, and the mixture was reacted at 80° C. for 12 hours to obtain a triazine porous polymer nanoparticle dispersion. 1.2 g of the above triazine porous polymer nanoparticle dispersion and 0.54 g of Sodium 2,4-diaminobenzenesulfonate and 0.10 g of dopamine hydrochloride were dispersed in 1000 g of an alkaline aqueous solution of sodium hydroxide with a pH of 10, and reacted at 25° C. and 1000 rpm for 1 hour to obtain an aqueous dispersion of sulfonated porous polymer nanoparticles; 12 g of zinc nitrate hexahydrate and 6 g of ethanolamine were dispersed in 1000 g of deionized water, magnetically stirred at 25° C. and 1000 rpm for 5 minutes, and allowed to stand for 20 minutes to obtain an aqueous solution of metal nanowires; 300 g of the aqueous dispersion of sulfonated porous polymer nanoparticles was added to polyvinylidene fluoride. The sulfonated porous polymer nanoparticle-metal nanowire composite membrane was immersed in 2-methylimidazole ethanol solution with a mass percentage concentration of 1.2% at 25°C for 4 hours to prepare a metal organic framework material by in situ growth on the surface. After washing with ethanol-water, the membrane was left to stand at 25°C for 4 hours to obtain a sulfonated porous polymer nanoparticle-metal organic framework composite cation exchange membrane.

[0030] Comparative Example 1

[0031] 0.5 g of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine was added to 250 g of 25 wt% acetic acid aqueous solution, and after dissolution, 0.5 g of acetone aldehyde and 0.3 g of formaldehyde were added to the above solution, and the mixture was reacted at 80° C. for 12 hours to obtain a triazine porous polymer nanoparticle dispersion. 1.2 g of the above triazine porous polymer nanoparticle dispersion was added to 1000 g of water to obtain a diluted triazine porous polymer nanoparticle dispersion. 300 g of the above diluted porous polymer nanoparticle aqueous dispersion was filtered on the surface of a polyvinylidene fluoride microfiltration membrane, washed with ethanol-water, and then left to air at 25° C. for 4 hours to obtain a polymer porous nanoparticle membrane.

[0032] Comparative Example 2

[0033] 0.5 g of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine was added to 250 g of 25 wt% acetic acid aqueous solution, and after dissolution, 0.5 g of acetone aldehyde and 0.3 g of formaldehyde were added to the above solution, and the mixture was reacted at 80° C. for 12 hours to obtain a triazine porous polymer nanoparticle dispersion. 1.2 g of the above triazine porous polymer nanoparticle dispersion, 0.54 g of sodium 2,4-diaminobenzenesulfonate and 0.10 g of dopamine hydrochloride were dispersed in 1000 g of a sodium hydroxide alkaline aqueous solution with a pH of 10, and the mixture was reacted at 25° C. and a speed of 1000 rpm for 1 hour to obtain a sulfonated porous polymer nanoparticle aqueous dispersion. 300 g of the above sulfonated porous polymer nanoparticle aqueous dispersion was filtered on the surface of a polyvinylidene fluoride microfiltration membrane, washed with ethanol-water, and then left to air at 25° C. for 4 hours to obtain a sulfonated polymer porous nanoparticle membrane.

[0034] Comparative Example 3

[0035] 0.5 g of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine was added to 250 g of 25 wt% acetic acid aqueous solution, and after dissolution, 0.5 g of acetone aldehyde and 0.3 g of formaldehyde were added to the above solution, and the mixture was reacted at 80° C. for 12 hours to obtain a triazine porous polymer nanoparticle dispersion. 1.2 g of the above triazine porous polymer nanoparticle dispersion and 0.54 g of Sodium 2,4-diaminobenzenesulfonate and 0.10g dopamine hydrochloride are dispersed in 1000g of sodium hydroxide alkaline aqueous solution with a pH of 10, and reacted at 25°C and 1000 rpm for 1 hour to obtain an aqueous dispersion of sulfonated porous polymer nanoparticles; 12g zinc nitrate hexahydrate and 6g ethanolamine are dispersed in 1000g deionized water and magnetically stirred at 1000 rpm for 5 minutes, and allowed to stand for 20 minutes to obtain an aqueous solution of metal nanowires; 300g of the above-mentioned sulfonated porous polymer nanoparticle aqueous dispersion is filtered on the surface of a polyvinylidene fluoride microfiltration membrane, and then 20g of the above-mentioned metal nanowire aqueous dispersion is vacuum filtered at 0.08MPa for 2 hours, washed with ethanol-water, and then allowed to stand at 25°C for 4 hours to obtain a sulfonated nanoparticle-metal nanowire composite membrane.

[0036] Table 1 Comparison of separation performance of cation selective exchange membranes prepared in Example 3 and Comparative Examples 1-3

[0037]

[0038] The results in Table 1 show that all four methods can produce cation-selective ion exchange membranes, but their selectivity for monovalent ions Li + and multivalent ions Mg 2+ The selectivity of cation selective membranes varies greatly due to the different chemical compositions, microstructures and preparation methods used to prepare cation selective membranes.

[0039] In Comparative Example 1, a triazine porous organic polymer is used as a membrane-forming material, and the polymer porous nanoparticle membrane obtained by vacuum filtration has greatly improved ion permeability because the porous nanomaterial provides more ion channels; however, due to the loose packing between the nanoparticles, defects are easily generated, resulting in low ion permeability selectivity; in Comparative Example 2, a sulfonated polymer porous nanoparticle membrane is prepared using sulfonated polymer porous nanoparticles as a membrane-forming material. Due to the difference in the interaction between the sulfonic acid group and the ion, the membrane has a low selectivity for Li + / Mg 2+ The ion permeation selectivity is improved; in Comparative Example 3, the density and surface positive charge of the membrane are improved by the strong electrostatic interaction between the metal nanowires and the sulfonated polymer porous nanoparticles. 2+ The hydration radius is larger than Li + The positively charged membrane surface repels multivalent cations more than monovalent cations, and the synergistic effect of steric hindrance and electrostatic repulsion further improves the ion permeation selectivity of the membrane.

[0040] In Example 3, metal nanowires are pre-assembled on the surface of sulfonated polymer porous nanoparticles by electrostatic action, and then the metal organic framework material is in situ grown on the membrane surface by the coordination between the organic ligand and the metal nanowires, and the ion transmission rate and separation selectivity in the membrane are improved by regulating the size of the "nanochannel" in the membrane, the charge of the channel wall and the hydrophilicity. Therefore, the sulfonated porous polymer nanoparticle-metal organic framework composite membrane has both high ion permeability and high single and multivalent cation separation selectivity.

[0041] Embodiment 4:

[0042] 0.5 g of 4,6-diamino-2-hydroxy-1,3,5-triazine was added to 250 g of 25 wt% acetic acid aqueous solution, and then 0.5 g of glyoxal and 0.3 g of propionaldehyde were added to the above solution after dissolution, and the mixture was reacted at 80° C. for 12 hours to obtain a triazine porous organic nanoparticle dispersion. 1.2 g of the above triazine porous polymer nanoparticle dispersion, 0.54 g of Sodium 2,4-diaminobenzenesulfonate and 0.10 g of dopamine hydrochloride were dispersed in 1000 g of an alkaline aqueous solution of sodium hydroxide with a pH of 10, and reacted at 25° C. and 1000 rpm for 1 hour to obtain an aqueous dispersion of sulfonated porous polymer nanoparticles; 12 g of cobalt nitrate hexahydrate and 6 g of ethanolamine were dispersed in 1000 g of deionized water, magnetically stirred at 25° C. and 1000 rpm for 5 minutes, and allowed to stand for 20 minutes to obtain an aqueous solution of metal nanowires; 300 g of the above aqueous dispersion of sulfonated porous polymer nanoparticles was added to the sulfonated polymer solution and stirred for 1 hour. The sulfone membrane surface is filtered, and then 20g of the above-mentioned metal nanowire aqueous dispersion is vacuum filtered at 0.08MPa for 2 hours to obtain a sulfonated nanoparticle-metal nanowire composite membrane; a 2-methylimidazole ethanol solution with a mass percentage concentration of 1.2% is immersed on the surface of the sulfonated porous polymer nanoparticle-metal nanowire composite membrane at 25°C for 4 hours, and a metal organic framework material is prepared by in situ growth on the surface; after washing with ethanol-water, it is left to air at 25°C for 4 hours to obtain a sulfonated porous polymer nanoparticle-metal organic framework composite cation exchange membrane.

[0043] Sulfonated porous nanoparticle-metal organic framework composite membrane at 25℃, 5mA·cm -2 Under electric field, the -1 LiCl and 0.1 mol·L -1 The separation results of the MgCl2 mixed liquid are as follows: the lithium ion flux is 8.3 mol·m -2 ·h -1 , the magnesium ion flux is 0.7 mol·m -2 ·h -1 , the magnesium-lithium ion permeation selectivity is 11.4.

[0044] Embodiment 5:

[0045] 0.5 g of 2,4-diamino-1,3,5-triazine was added to 250 g of 25 wt% acetic acid aqueous solution, and after dissolution, 0.5 g of 1,2-cyclohexanedione and 0.3 g of benzaldehyde were added to the above solution, and the mixture was reacted at 80° C. for 12 hours to obtain a triazine porous organic nanoparticle dispersion. 1.2 g of the above triazine porous polymer nanoparticle dispersion, 0.54 g of sodium p-aminobenzenesulfonate and 0.10 g of dopamine hydrochloride were dispersed in 1000 g of sodium hydroxide alkaline aqueous solution with a pH of 10, and the mixture was reacted at 25° C. and 1000 rpm for 1 hour to obtain a sulfonated porous polymer nanoparticle aqueous dispersion. 12 g of cobalt acetate hexahydrate and 6 g of ethylenediamine were dispersed in 1000 g of deionized water, and magnetically stirred at 25° C. and 1000 rpm for 5 minutes, and allowed to stand for 20 minutes. Obtain a metal nanowire aqueous solution; take 300g of the above-mentioned sulfonated porous polymer nanoparticle aqueous dispersion and filter it on the surface of a polysulfone membrane, and then take 20g of the above-mentioned metal nanowire aqueous dispersion and vacuum filter it at 0.08MPa for 2 hours to obtain a sulfonated nanoparticle-metal nanowire composite membrane; immerse the surface of the sulfonated porous polymer nanoparticle-metal nanowire composite membrane with a mass percentage concentration of 1.2% benzimidazole ethanol solution at 25°C for 4 hours, and prepare a metal organic framework material by in situ growth on the surface; after washing with ethanol-water, let it stand at 25°C for 4 hours to obtain a sulfonated porous polymer nanoparticle-metal organic framework composite cation exchange membrane.

[0046] Sulfonated porous nanoparticle-metal organic framework composite membrane at 25℃, 5mA·cm -2 Under electric field, the -1 LiCl and 0.1 mol·L -1 The separation results of the MgCl2 mixed liquid are as follows: the lithium ion flux is 5.8 mol·m -2 ·h -1 , the magnesium ion flux is 0.5 mol·m -2 ·h -1 , the magnesium-lithium ion permeation selectivity is 17.0.

[0047] Embodiment 6:

[0048] 0.5 g of 2,4-diamino-[N,N'-di(4'-p-aminobenzylbenzene)]-6-phenyl-1,3,5-triazine was added to 250 g of 25 wt% acetic acid aqueous solution, and after dissolution, 0.5 g of 1,4-di(phenyloxalyl)benzene and 0.3 g of terephthalaldehyde were added to the above solution, and the mixture was reacted at 80° C. for 12 hours to obtain a triazine porous organic nanoparticle dispersion. 1.2 g of the above triazine porous polymer nanoparticle dispersion and 0.54 g of Sodium 2,4-diaminobenzenesulfonate and 0.10 g of dopamine hydrochloride were dispersed in 1000 g of potassium hydroxide alkaline aqueous solution with a pH of 10, and reacted at 25° C. and 1000 rpm for 1 hour to obtain an aqueous dispersion of sulfonated porous polymer nanoparticles; 12 g of zinc acetate and 6 g of triethylamine were dispersed in 1000 g of deionized water, magnetically stirred at 25° C. and 1000 rpm for 5 minutes, and allowed to stand for 20 minutes to obtain an aqueous solution of metal nanowires; 300 g of the above aqueous dispersion of sulfonated porous polymer nanoparticles was added to the sulfonated polymer solution and stirred for 1 hour. The sulfone membrane surface is filtered, and then 20g of the above-mentioned metal nanowire aqueous dispersion is vacuum filtered at 0.08MPa for 2 hours to obtain a sulfonated nanoparticle-metal nanowire composite membrane; a benzimidazole ethanol solution with a mass percentage concentration of 1.2% is immersed on the surface of the sulfonated porous polymer nanoparticle-metal nanowire composite membrane at 25°C for 4 hours, and a metal organic framework material is prepared by in situ growth on the surface; after washing with ethanol-water, it is left to air at 25°C for 4 hours to obtain a sulfonated porous polymer nanoparticle-metal organic framework composite cation exchange membrane.

[0049] Sulfonated porous nanoparticle-metal organic framework composite membrane at 25℃, 5mA·cm -2 Under electric field, the -1 LiCl and 0.1 mol·L -1 The separation results of the MgCl2 mixed liquid are as follows: the lithium ion flux is 9.8 mol·m -2 ·h -1 , the magnesium ion flux is 1.1 mol·m -2 ·h -1 , the magnesium-lithium ion permeation selectivity is 16.1.

[0050] Embodiment 7:

[0051] 0.5 g of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine was added to 250 g of 25 wt% acetic acid aqueous solution, and after dissolution, 0.5 g of diphenylethanedione and 0.3 g of formaldehyde were added to the above solution, and the mixture was reacted at 80° C. for 12 hours to obtain a triazine porous organic nanoparticle dispersion. 1.2 g of the above triazine porous polymer nanoparticle dispersion and 0.54 g of Sodium 2,4-diaminobenzenesulfonate and 0.10 g of dopamine hydrochloride were dispersed in 1000 g of potassium hydroxide alkaline aqueous solution with a pH of 10, and reacted at 25° C. and 1000 rpm for 1 hour to obtain an aqueous dispersion of sulfonated porous polymer nanoparticles; 9.0 g of ferric chloride and 3.0 g of ethanolamine were dispersed in 1000 g of deionized water, magnetically stirred at 25° C. and 1000 rpm for 5 minutes, and allowed to stand for 20 minutes to obtain an aqueous solution of metal nanowires; 300 g of the above aqueous dispersion of sulfonated porous polymer nanoparticles was added to polyvinylidene fluoride. The sulfonated porous polymer nanoparticle-metal nanowire composite membrane was immersed in a methanol solution of trimesic acid having a mass percentage concentration of 0.5% at 25°C for 4 hours to prepare a metal organic framework material by in situ growth on the surface. After washing with ethanol-water, the membrane was left to air at 25°C for 4 hours to obtain a sulfonated porous polymer nanoparticle-metal organic framework composite cation exchange membrane.

[0052] Sulfonated porous nanoparticle-metal organic framework composite membrane at 25℃, 5mA·cm -2 Under electric field, the -1 LiCl and 0.1 mol·L -1 The separation results of the MgCl2 mixed liquid are as follows: the lithium ion flux is 7.3 mol·m -2 ·h -1 , the magnesium ion flux is 1.00 mol·m -2 ·h -1 , the magnesium-lithium ion permeation selectivity is 15.3.

[0053] Embodiment 8:

[0054] 0.5 g of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine was added to 250 g of 25 wt% acetic acid aqueous solution, and after dissolution, 0.5 g of diphenylethanedione and 0.3 g of acrolein were added to the above solution, and the mixture was reacted at 80° C. for 12 hours to obtain a triazine porous organic nanoparticle dispersion. 1.2 g of the above triazine porous polymer nanoparticle dispersion, 0.54 g of sodium 2,4-diaminobenzenesulfonate and 0.10 g of dopamine hydrochloride were dispersed in 1000 g of a sodium hydroxide alkaline aqueous solution with a pH of 10, and the mixture was reacted at 25° C. and 1000 rpm for 1 hour to obtain a sulfonated porous polymer nanoparticle aqueous dispersion. 10.0 g of copper nitrate trihydrate and 3 g of ethanolamine were dispersed in 1000 g of deionized water and stirred at 25° C. and 1000 rpm for 1 hour. Stir for 5 minutes, let stand for 20 minutes to obtain a metal nanowire aqueous solution; take 300g of the above-mentioned sulfonated porous polymer nanoparticle aqueous dispersion and filter it on the surface of a polyvinylidene fluoride microfiltration membrane, and then take 20g of the above-mentioned metal nanowire aqueous dispersion and vacuum filter it at 0.08MPa for 2 hours to obtain a sulfonated nanoparticle-metal nanowire composite membrane; use a 0.5% by mass percentage concentration of trimesic acid methanol solution to immerse the surface of the sulfonated porous polymer nanoparticle-metal nanowire composite membrane at 25°C for 4 hours, and in situ grow the surface to prepare a metal organic framework material, after washing with ethanol-water, let it stand at 25°C for 4 hours to obtain a sulfonated porous polymer nanoparticle-metal organic framework composite cation exchange membrane.

[0055] Sulfonated porous nanoparticle-metal organic framework composite membrane at 25℃, 5mA·cm -2 Under electric field, the -1 LiCl and 0.1 mol·L -1 The separation results of the MgCl2 mixed liquid are as follows: the lithium ion flux is 7.7 mol·m -2 .h -1 , the magnesium ion flux is 1.1 mol·m -2 ·h -1 , the magnesium-lithium ion permeation selectivity is 13.0.

Claims

1. A method for preparing a sulfonated porous polymer nanoparticle-metal organic framework composite cation exchange membrane, characterized in that: The preparation method comprises the following steps: 1) adding 0.05-1.0 parts by weight of a triazine derivative to 25-500 parts by weight of an acetic acid aqueous solution, and adding 0.2-1.2 parts by weight of a 1,2-dicarbonyl compound and 0.05-0.6 parts by weight of an aldehyde compound to the above solution after dissolution, and reacting at 60-120° C. for 12-72 hours to obtain a triazine porous polymer nanoparticle dispersion, dispersing 0.3-1.5 parts by weight of the above triazine porous polymer nanoparticle dispersion, 0.15-0.90 parts by weight of aminosulfonate and 0.05-0.25 parts by weight of dopamine hydrochloride in 1000 parts by weight of an alkaline aqueous solution, and reacting under magnetic stirring to obtain an aqueous dispersion of sulfonated porous polymer nanoparticles; 2) dispersing 5 to 20 parts by weight of a metal acid salt and 2 to 10 parts by weight of an organic amine in 1000 parts by weight of deionized water, stirring the mixture by magnetic force and standing the mixture for 10 to 50 minutes to obtain a metal nanowire aqueous dispersion, filtering 100 to 500 parts by weight of the sulfonated porous polymer nanoparticle aqueous dispersion on the surface of a porous support membrane, and then filtering 5 to 25 parts by weight of the metal nanowire aqueous dispersion to form a sulfonated porous polymer nanoparticle-metal nanowire composite membrane; 3) impregnating the surface of the sulfonated porous polymer nanoparticle-metal nanowire composite membrane with an organic ligand solution to prepare a metal organic framework material by in-situ growth on the surface, washing with ethanol-water, and airing at 15-35° C. for 2-6 hours to obtain a sulfonated porous polymer nanoparticle-metal organic framework composite cation exchange membrane; The triazine derivatives are composed of one or more of 2,4-diamino-1,3,5-triazine, 4,6-diamino-2-hydroxy-1,3,5-triazine, 2,4-diamino-[N,N'-di(4'-p-aminobenzylbenzene)]-6-phenyl-1,3,5-triazine, and 2,4,6-tris(4-aminophenyl)-1,3,5-triazine in any proportion; the 1,2-dicarbonyl compound is composed of one or more of methylglyoxal, glyoxal, 1,2-cyclohexanedione, diphenylethanedione, and 1,4-di(phenylethanediyl)benzene in any proportion; the aldehyde compound is formaldehyde, propionaldehyde, benzaldehyde, propylene The invention relates to a novel nanostructured polymer comprising one or more of aldehyde and terephthalaldehyde mixed in any proportion; the aminosulfonate is one or more of 2,4-diaminobenzenesulfonic acid sodium and sodium p-aminobenzenesulfonate mixed in any proportion; the metal acid salt is one or more of zinc nitrate, zinc acetate, ferric chloride, copper nitrate, cobalt nitrate or cobalt acetate mixed in any proportion; the organic amine is one or more of ethanolamine, ethylenediamine and triethylamine mixed in any proportion; the porous support membrane is one of polyvinylidene fluoride, polysulfone or sulfonated polysulfone; the organic ligand is one or more of 2-methylimidazole, benzimidazole or trimesic acid mixed in any proportion.

2. The preparation method according to claim 1, characterized in that: The mass percentage concentration of the acetic acid aqueous solution in step 1) is 10-50%.

3. The preparation method according to claim 1, characterized in that: The alkaline aqueous solution described in step 1) is a sodium hydroxide or potassium hydroxide aqueous solution with a mass percentage concentration of 0.01 to 0.1%.

4. The preparation method according to claim 1, characterized in that: The reaction conditions under magnetic stirring in step 1) are 15-35° C. and 500-1500 rpm for 1-3 hours.

5. The preparation method according to claim 1, characterized in that: The magnetic stirring condition in step 2) is 800-1500 rpm at 15-35° C. for 5-10 minutes.

6. The preparation method according to claim 1, characterized in that: In step 2), the filtering condition on the surface of the porous support membrane is filtering for 1 to 3 hours at an operating pressure of 0.05 to 0.10 MPa.

7. The preparation method according to claim 1, characterized in that: The mass percentage concentration of the organic ligand solution in step 3) is 0.4-4%.

8. The preparation method according to claim 1, characterized in that: The solvent of the organic ligand solution in step 3) is water, methanol or ethanol.

9. The preparation method according to claim 1, characterized in that: The immersion treatment condition of the organic ligand solution in step 3) is immersion at 15-35° C. for 0.5-6 hours.

10. A sulfonated porous polymer nanoparticle-metal organic framework composite cation exchange membrane prepared by the preparation method according to any one of claims 1 to 9.

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