A crosslinked bipolar membrane, its preparation method and application

Abstract

The present invention belongs to the field of compound preparation, and relates to a crosslinked bipolar membrane, a preparation method thereof and an application. The crosslinked bipolar membrane comprises a crosslinked base membrane, a cation exchange membrane and an anion exchange membrane which are respectively located on two side surfaces of the crosslinked base membrane; the crosslinked base membrane is prepared by the following method: impregnating a high molecular weight polyethylene support layer in a polymerization monomer impregnating solution containing low molecular weight polyethylene, styrene, divinylbenzene, an initiator and a MOF material, and after the impregnation is completed, carrying out a polymerization reaction on the support layer under an inert atmosphere to obtain the crosslinked base membrane; the cation exchange membrane is formed by polymer I; the anion exchange membrane is formed by polymer II, and the polymer II is a copolymer obtained by copolymerizing diallyldimethylammonium chloride and allyltrimethylammonium chloride. Using the crosslinked bipolar membrane provided by the present invention in the electrolysis of high-concentration salt-containing production wastewater by bipolar membrane electrodialysis can continuously and efficiently obtain hydrochloric acid and sodium hydroxide, and has broad application prospects.

Description

Technical Field

[0001] The invention belongs to the field of compound preparation and relates to a cross-linked bipolar membrane and a preparation method and application thereof. Background Art

[0002] Hydrochloric acid is an aqueous solution of hydrogen chloride, which is a colorless liquid. Hydrochloric acid has a wide range of uses in biology, industry, and daily life. For example, in the biological field, hydrochloric acid is one of the main components of gastric acid, which can promote the conversion of pepsinogen into active pepsin and provide the necessary acidic environment, promote the decomposition of substances such as protein, fat, and starch, and play a role in promoting digestion; hydrochloric acid is an important component of the intestinal mucosal barrier, which can prevent the invasion or colonization of potential pathogens, maintain the function and structural integrity of the intestinal mucosal barrier, and kill bacteria that enter the stomach with food; hydrochloric acid can also enter the small intestine to cause the release of secretin and cholecystokinin, promote the secretion of pancreatic juice, bile, and small intestinal juice, thereby promoting the digestion process. In the industrial field, hydrochloric acid, as a strong acid, can be used to neutralize various alkali solutions and adjust the pH value of the solution; hydrochloric acid is often used for pickling steel, removing oxides and rust on the surface of steel, and improving the surface quality and subsequent processing performance of steel; hydrochloric acid is an important raw material for manufacturing a variety of chemical products, such as fertilizers (nitrogen fertilizers, phosphate fertilizers), plastics (polyvinyl chloride PVC), dyes, etc. In daily life, hydrochloric acid can not only be used to make cleaning agents such as toilet cleaners to effectively remove various stains and dirt, but can also be used to remove rust on metal surfaces to restore the gloss and performance of the metal surface.

[0003] Sodium hydroxide, also known as caustic soda, caustic soda or caustic soda, is a strong alkaline compound with a wide range of uses. Hydrochloric acid has a wide range of uses in industry, food, and daily life. In industry, sodium hydroxide can be used to treat natural fibers such as cotton and linen, remove non-fibrous substances such as cottonseed hulls and wax, and improve the quality of textiles; sodium hydroxide can be used as a sizing agent for fabrics to make the fabrics soft and breathable and prevent hair loss, and can also be used to bleach textiles such as silk; sodium hydroxide is the basic raw material for the production of a variety of chemical products, and can be used to produce chemicals such as borax, sodium cyanide, formic acid, oxalic acid, and phenol. In food, sodium hydroxide can be used as a food processing aid, used in container cleaning, starch processing, preparation of carboxymethyl cellulose, manufacturing of sodium glutamate, etc., used as a food acidity regulator, leavening agent, etc., as a peeling agent for citrus, peaches, etc. In daily life, sodium hydroxide is one of the raw materials for making soaps and detergents.

[0004] Using bipolar membrane electrodialysis for high-concentration production wastewater is one of the methods for co-producing hydrochloric acid and sodium hydroxide. Although the bipolar membrane electrodialysis method has the advantages of low energy consumption, simple operation and easy scale-up compared with the chemical synthesis method for preparing hydrochloric acid and sodium hydroxide, it cannot efficiently produce hydrochloric acid and sodium hydroxide, and the bipolar membrane has a short lifespan. As the usage time of the bipolar membrane extends, the production efficiency of hydrochloric acid and sodium hydroxide will decrease significantly, and the stability is poor. Summary of the Invention

[0005] The first object of the present invention is to provide a crosslinked bipolar membrane that can improve the production efficiency of hydrochloric acid and sodium hydroxide and has good stability.

[0006] The second object of the present invention is to provide a preparation method of the above crosslinked bipolar membrane.

[0007] The third object of the present invention is to provide the application of the above crosslinked bipolar membrane in the resource recovery of production wastewater containing high-concentration salts.

[0008] Specifically, the crosslinked bipolar membrane provided by the present invention includes a crosslinked base membrane, a cation exchange membrane and an anion exchange membrane respectively located on both surface sides of the crosslinked base membrane; the crosslinked base membrane is prepared by the following method: impregnating a high-molecular-weight polyethylene support layer in a polymerization monomer impregnating solution containing low-molecular-weight polyethylene, styrene, divinylbenzene, an initiator and a MOF material, and after the impregnation is completed, carrying out a polymerization reaction on the support layer under an inert atmosphere to obtain the crosslinked base membrane; the cation exchange membrane is formed by a polymer I having the structure shown in formula (1); the anion exchange membrane is formed by a polymer II, and the polymer II is a copolymer obtained by copolymerizing diallyldimethylammonium chloride and allyltrimethylammonium chloride in a molar ratio of 1:(0.01-0.1);

[0009]

[0010] The preparation method of the crosslinked bipolar membrane provided by the present invention includes the following steps:

[0011] S21. Immerse the high molecular weight polyethylene support layer in a polymerization monomer impregnation solution containing low molecular weight polyethylene, styrene, divinylbenzene, initiator and MOF material. After impregnation, carry out a polymerization reaction on the support layer under an inert atmosphere to obtain a crosslinked base membrane; Feed butadiene into an organic solvent for polymerization reaction, and then carry out a thiol-ene click reaction on the obtained polybutadiene and sodium 3-(5-mercapto-1-tetrazolyl)benzenesulfonate to obtain a solution containing Polymer I; Spray the solution containing Polymer I on the surface of the substrate and dry it. Then peel the film layer from the surface of the substrate to obtain a cation exchange membrane; Feed diallyldimethylammonium chloride, allyltrimethylammonium chloride and an inorganic peroxide initiator in a molar ratio of 1:(0.01-0.1):(0.001-0.01) into an organic solvent for copolymerization reaction to obtain a solution containing a copolymer; Spray the solution containing the copolymer on the surface of the substrate and dry it. Then peel the film layer from the surface of the substrate to obtain an anion exchange membrane;

[0012] S22. Bond the cation exchange membrane and the anion exchange membrane to the upper and lower surfaces of the crosslinked base membrane respectively and then hot press to obtain a crosslinked bipolar membrane.

[0013] The key of the present invention lies in using a specific crosslinked base membrane as the substrate. The cation exchange membrane is formed by a polymer shown in formula (1), and at the same time, the anion exchange membrane is formed by a copolymer of diallyldimethylammonium chloride and allyltrimethylammonium chloride. The obtained crosslinked bipolar membrane can continuously and efficiently obtain hydrochloric acid and sodium hydroxide when used in the bipolar membrane electrodialysis of high-concentration salt-containing production wastewater. Presumably, the reason may be that: on the one hand, the MOF material can improve the efficiency of water electrolysis of the bipolar membrane, and can provide more H - in the Cl + in the acid chamber, and provide more OH + for the Na - in the alkali chamber, thereby promoting the synthesis of hydrochloric acid and sodium hydroxide; on the other hand, the existing bipolar membranes usually have an aromatic carbon skeleton, but the carbon-oxygen bond in the aromatic carbon skeleton is easily attacked by the H + and OH - generated by the bipolar membrane and cause aging. However, high molecular weight polyethylene, the polymer formed by the polymerization of low molecular weight polyethylene, styrene and divinylbenzene, Polymer I, and the copolymer of diallyldimethylammonium chloride and allyltrimethylammonium chloride all have a carbon-carbon double bond main chain and are not easily attacked by H + and OH - to cause aging. At the same time, sodium benzenesulfonate groups and azacyclic functional groups are evenly distributed on the side chains of the polymer shown in formula (1). The presence of the azacyclic functional groups can make the electron distribution of the polymer more uniform, thereby endowing the polymer with stronger acid and alkali resistance, making the bipolar membrane in high-concentration H + and OH- It can operate stably and continuously in the environment. Moreover, the polymer shown in formula (1) has a relatively flexible main chain provided by C-C and a relatively rigid side chain provided by the sodium benzenesulfonate group / heterocyclic nitrogen functional group. The flexible main chain can improve the impact resistance of the bipolar membrane, making it have good tolerance to the flow of liquid during use. The introduction of the rigid side chain and the cross-linked polystyrene / divinylbenzene in the cross-linked base membrane and the cross-linked poly(diallyldimethylammonium chloride) / allyltrimethylammonium chloride in the anion exchange membrane can synergistically improve the support force of the cross-linked bipolar membrane, making the bipolar membrane not easily affected by the impact of liquid flow disturbance and thus affecting its service life.

[0014] In a preferred embodiment, the MOF material is a modified MOF material co-modified by Fe and Cu. At this time, the production efficiency of hydrochloric acid and sodium hydroxide can be further improved. Presumably, the reason may be that: ferric ions and copper ions can synergistically improve the reactivity of water, weaken the molecular bond, and accelerate the hydrolysis dissociation in the middle layer of the bipolar membrane into H + and OH - , thereby promoting the synthesis of hydrochloric acid and sodium hydroxide. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic structural diagram of the two-compartment bipolar membrane electrodialysis device used in the test example. DETAILED DESCRIPTION OF THE INVENTION

[0016] The cross-linked bipolar membrane provided by the present invention includes a cation exchange membrane, a cross-linked base membrane, and an anion exchange membrane stacked in sequence; the cation exchange membrane is formed by polymer I, and the anion exchange membrane is formed by polymer II. In a preferred embodiment, the thickness of the cation exchange membrane is 5-20 microns, specifically 5 microns, 8 microns, 10 microns, 12 microns, 15 microns, 18 microns, 20 microns or any value between them; the thickness of the cross-linked base membrane is 10-30 microns, specifically 10 microns, 12 microns, 15 microns, 18 microns, 20 microns, 22 microns, 24 microns, 26 microns, 28 microns, 30 microns or any value between them; the thickness of the anion exchange membrane is 5-20 microns, specifically 5 microns, 8 microns, 10 microns, 12 microns, 15 microns, 18 microns, 20 microns or any value between them.

[0017] In the present invention, the crosslinked base film is prepared by the following method: impregnating a high molecular weight polyethylene support layer in a polymerization monomer impregnating solution containing low molecular weight polyethylene, styrene, divinylbenzene, an initiator, and an MOF material, and after the impregnation is completed, carrying out a polymerization reaction on the support layer under an inert atmosphere to obtain the crosslinked base film. During the formation of the crosslinked base film, the low molecular weight polyethylene, styrene, and divinylbenzene can form a crosslinked polymer on the surface and inside of the high molecular weight polyethylene support layer, thereby enhancing the mechanical strength of the high molecular weight polyethylene support layer. Among them, the number average molecular weight of the high molecular weight polyethylene in the high molecular weight polyethylene support layer is preferably 10,000 to 50,000, and specifically can be 10,000, 15,000, 20,000, 25,000, 30,000, 35,000, 40,000, 45,000, 50,000, or any value between them. The mass ratio of the low molecular weight polyethylene, styrene, divinylbenzene, initiator, and MOF material in the polymerization monomer impregnating solution is preferably 100:(50 to 80):(5 to 10):(1 to 5):(10 to 20). Based on the amount of the low molecular weight polyethylene being 100 parts by weight, the amount of the styrene is preferably 50 to 80 parts by weight, and specifically can be 50, 55, 60, 65, 70, 75, 80 parts by weight, or any value between them; the amount of the divinylbenzene is preferably 5 to 10 parts by weight, such as 5, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10 parts by weight, or any value between them; the content of the initiator is preferably 1 to 5 parts by weight, such as 1, 2, 3, 4, 5 parts by weight, or any value between them; the amount of the MOF material is preferably 10 to 20 parts by weight, such as 10, 12, 14, 16, 18, 20 parts by weight, or any value between them. The number average molecular weight of the low molecular weight polyethylene is preferably 1,000 to 5,000, and specifically can be 1,000, 2,000, 3,000, 4,000, 5,000, or any value between them. The initiator is preferably an azo initiator, and examples thereof include at least one of azobisisobutyronitrile (AIBN), azobisisoheptonitrile (ABVN), dimethyl azobisisobutyrate (AIBME), and azoisobutyronitrile formamide (V30).

[0018] In the present invention, the MOF material can be an unmodified MOF material or a modified MOF material. The modified MOF material can be an Fe-modified MOF material, and particularly preferably an Fe and Cu co-modified MOF material.

[0019] In a preferred embodiment, the Fe and Cu co-modified MOF material is prepared by the following method: S11. Dispersing 3,5-pyrazoledicarboxylic acid in an alkaline solution, adding aluminum chloride to the obtained dispersion and stirring until dissolved, then heating the obtained solution at 90-110 °C for 10-48 h and filtering, and drying the obtained precipitate to obtain a MOF support; S12. Activating the MOF support at 140-160 °C for 10-24 h, then dispersing the obtained activated MOF support, ferric nitrate and copper nitrate in an organic solvent, and then raising the temperature to 60-80 °C and reacting for 10-48 h. After the reaction is completed, it is cooled to room temperature to obtain a solution containing the modified MOF material. Wherein, the mass ratio of the MOF support, ferric nitrate and copper nitrate is preferably 1:(0.5-0.8):(0.1-0.3). Specifically, based on the amount of the MOF support being 1 part by weight, the amount of ferric nitrate is 0.5-0.8 parts by weight, such as 0.5, 0.6, 0.7, 0.8 parts by weight or any value therebetween; the amount of copper nitrate is 0.1-0.3 parts by weight, such as 0.1, 0.15, 0.2, 0.25, 0.3 parts by weight or any value therebetween.

[0020] In the present invention, the cation exchange membrane is formed of a polymer I having the structure shown in formula (1).

[0021]

[0022] The present invention places no particular limitation on the source of Polymer I, as long as it has the structure shown in Formula (1). In a preferred embodiment, Polymer I is prepared by the following method: Butadiene is fed into an organic solvent for polymerization reaction, and then the obtained polybutadiene is subjected to a thiol-ene click reaction with sodium 3-(5-mercapto-1-tetrazolyl)benzenesulfonate to obtain a solution containing Polymer I. Among them, the conditions of the polymerization reaction preferably include a polymerization temperature of 50 to 100 °C, such as 50 °C, 60 °C, 70 °C, 80 °C, 90 °C, 100 °C or any value between them; a polymerization pressure of 0.1 to 0.5 MPa, such as 0.1 MPa, 0.2 MPa, 0.3 MPa, 0.4 MPa, 0.5 MPa or any value between them; a polymerization time of 0.5 to 10 h, such as 0.5 h, 1 h, 2 h, 4 h, 6 h, 8 h, 10 h or any value between them. The molar ratio of butadiene to sodium 3-(5-mercapto-1-tetrazolyl)benzenesulfonate is preferably (0.9 to 1.1):1, such as 0.9:1, 0.95:1, 1:1, 1.05:1, 1.1:1 or any value between them. The conditions of the thiol-ene click reaction preferably include a temperature of 70 to 100 °C, such as 70 °C, 75 °C, 80 °C, 85 °C, 90 °C, 95 °C, 100 °C or any value between them; a polymerization pressure of 0.1 to 0.5 MPa, such as 0.1 MPa, 0.2 MPa, 0.3 MPa, 0.4 MPa, 0.5 MPa or any value between them; a polymerization time of 0.5 to 5 h, such as 0.5 h, 1 h, 2 h, 4 h, 5 h or any value between them.

[0023] In the present invention, the anion exchange membrane is formed of Polymer II, and Polymer II is a copolymer obtained by copolymerizing diallyldimethylammonium chloride (having the structure shown in Formula (2)) and allyltrimethylammonium chloride (having the structure shown in Formula (3)) in a molar ratio of 1:(0.01 to 0.1). The copolymer is a crosslinked polymer. Among them, the conditions of the copolymerization reaction preferably include a copolymerization temperature of 50 to 100 °C, such as 50 °C, 60 °C, 70 °C, 80 °C, 90 °C, 100 °C or any value between them; a copolymerization pressure of 0.1 to 0.5 MPa, such as 0.1 MPa, 0.2 MPa, 0.3 MPa, 0.4 MPa, 0.5 MPa or any value between them; a copolymerization time of 0.5 to 10 h, such as 0.5 h, 1 h, 2 h, 4 h, 6 h, 8 h, 10 h or any value between them. The copolymerization reaction is generally carried out in the presence of an inorganic peroxide initiator. Examples of the inorganic peroxide initiator include at least one of potassium persulfate, sodium persulfate, ammonium persulfate, etc.

[0024]

[0025] In the present invention, the terms "Ⅰ" and "Ⅱ" are only used to distinguish the same substance that appears at different times for the convenience of description, and have no other special meanings. In addition, the pressures mentioned are all gauge pressures.

[0026] The preparation method of the crosslinked bipolar membrane provided by the present invention comprises the following steps:

[0027] S21. Immerse the high molecular weight polyethylene support layer in a polymerization monomer impregnation solution containing low molecular weight polyethylene, styrene, divinylbenzene, an initiator and a MOF material. After the impregnation is completed, carry out a polymerization reaction on the support layer under an inert atmosphere to obtain a crosslinked base membrane; Feed butadiene into an organic solvent for a polymerization reaction, and then carry out a thiol-ene click reaction on the obtained polybutadiene and sodium 3-(5-mercapto-1-tetrazolyl)benzenesulfonate to obtain a solution containing polymer Ⅰ; Spray the solution containing polymer Ⅰ on the surface of the substrate and dry it, and then peel the film layer from the surface of the substrate to obtain a cation exchange membrane; Feed diallyldimethylammonium chloride, allyltrimethylammonium chloride and an inorganic peroxide initiator in a molar ratio of 1:(0.01-0.1):(0.001-0.01) into an organic solvent for a copolymerization reaction to obtain a solution containing a copolymer; Spray the solution containing the copolymer on the surface of the substrate and dry it, and then peel the film layer from the surface of the substrate to obtain an anion exchange membrane;

[0028] S22. Bond the cation exchange membrane and the anion exchange membrane to the upper and lower surfaces of the crosslinked base membrane respectively, and then carry out hot pressing to obtain the crosslinked bipolar membrane.

[0029] In the preparation process of the above crosslinked bipolar membrane, in step S11, the preparation raw materials and conditions of the crosslinked base membrane, polymer Ⅰ and copolymer have been described above, and will not be elaborated here.

[0030] In the preparation process of the above crosslinked bipolar membrane, in step S22, the conditions of the hot pressing preferably include a hot pressing temperature of 200-400°C, such as 200°C, 220°C, 240°C, 260°C, 280°C, 300°C, 320°C, 340°C, 360°C, 380°C, 400°C or any value between them; a hot pressing pressure of 5-20 MPa, such as 5 MPa, 8 MPa, 10 MPa, 12 MPa, 14 MPa, 16 MPa, 18 MPa, 20 MPa or any value between them; a hot pressing time of 10-60 min, such as 10 min, 20 min, 30 min, 40 min, 50 min, 60 min or any value between them.

[0031] The present invention also provides the application of the above crosslinked bipolar membrane in the resource recovery of production wastewater containing high-concentration salts. Among them, the production wastewater containing high-concentration salts can be, for example, concentrated seawater.

[0032] The present invention will be described in detail below by way of examples.

[0033] Preparation Example 1-1

[0034] Butadiene was fed into toluene and reacted at a temperature of 100 °C and a pressure of 0.1 MPa for 0.5 h. Sodium 3-(5-mercapto-1-tetrazolyl)benzenesulfonate was added to the obtained polybutadiene solution, and then reacted at a temperature of 70 °C and a pressure of 0.5 MPa for 5 h. The molar ratio of sodium 3-(5-mercapto-1-tetrazolyl)benzenesulfonate to butadiene was 1:1, and a solution containing Polymer I with a concentration of 5 wt% was obtained.

[0035] Preparation Example 1-2

[0036] Butadiene was fed into toluene and reacted at a temperature of 50 °C and a pressure of 0.5 MPa for 10 h. Sodium 3-(5-mercapto-1-tetrazolyl)benzenesulfonate was added to the obtained polybutadiene solution, and then reacted at a temperature of 70 °C and a pressure of 0.5 MPa for 5 h. The molar ratio of sodium 3-(5-mercapto-1-tetrazolyl)benzenesulfonate to butadiene was 0.9:1, and a solution containing Polymer I with a concentration of 10 wt% was obtained.

[0037] Preparation Example 1-3

[0038] Butadiene was fed into toluene and reacted at a temperature of 80 °C and a pressure of 0.3 MPa for 5 h. Sodium 3-(5-mercapto-1-tetrazolyl)benzenesulfonate was added to the obtained polybutadiene solution, and then reacted at a temperature of 80 °C and a pressure of 0.3 MPa for 2 h. The molar ratio of sodium 3-(5-mercapto-1-tetrazolyl)benzenesulfonate to butadiene was 0.9:1, and a solution containing Polymer I with a concentration of 3 wt% was obtained.

[0039] Comparative Preparation Example 1-1

[0040] Butadiene was fed into trichloroethane and reacted at a temperature of 100 °C and a pressure of 0.1 MPa for 0.5 h to obtain a reference solution containing Polymer I with a concentration of 5 wt%.

[0041] Preparation Example 2-1

[0042] S11. 5 g of 3,5-pyrazoledicarboxylic acid monohydrate was dispersed in 1 L of an aqueous sodium hydroxide solution with a concentration of 0.3 wt%. 10 g of aluminum chloride was added to the obtained dispersion and stirred until dissolved. Then, the obtained solution was heated at 90 °C for 48 h and filtered. The obtained precipitate was vacuum dried at 60 °C for 2 h to obtain a MOF support;

[0043] S12. Activate the MOF support at 140 °C for 24 h, then disperse the obtained activated MOF support, ferric nitrate, and copper nitrate in acetonitrile according to a mass ratio of 1:0.5:0.1, and then raise the temperature to 70 °C and react for 24 h. After the reaction is completed, cool it to room temperature to obtain a solution containing the modified MOF material with a concentration of 5 wt%.

[0044] Preparation Example 2-2

[0045] S11. Disperse 5 g of 3,5-pyrazoledicarboxylic acid monohydrate in 1 L of an aqueous sodium hydroxide solution with a concentration of 0.3 wt%. Add 10 g of aluminum chloride to the obtained dispersion and stir until dissolved. Then heat the obtained solution at 110 °C for 10 h and filter. Vacuum dry the obtained precipitate at 60 °C for 2 h to obtain the MOF support.

[0046] S12. Activate the MOF support at 160 °C for 10 h, then disperse the obtained activated MOF support, ferric nitrate, and copper nitrate in acetonitrile according to a mass ratio of 1:0.8:0.3, and then raise the temperature to 60 °C and react for 48 h. After the reaction is completed, cool it to room temperature to obtain a solution containing the modified MOF material with a concentration of 5 wt%.

[0047] Preparation Example 2-3

[0048] S11. Disperse 5 g of 3,5-pyrazoledicarboxylic acid monohydrate in 1 L of an aqueous sodium hydroxide solution with a concentration of 0.3 wt%. Add 10 g of aluminum chloride to the obtained dispersion and stir until dissolved. Then heat the obtained solution at 100 °C for 24 h and filter. Vacuum dry the obtained precipitate at 60 °C for 2 h to obtain the MOF support.

[0049] S12. Activate the MOF support at 150 °C for 15 h, then disperse the obtained activated MOF support, ferric nitrate, and copper nitrate in acetonitrile according to a mass ratio of 1:0.6:0.2, and then raise the temperature to 80 °C and react for 10 h. After the reaction is completed, cool it to room temperature to obtain a solution containing the modified MOF material with a concentration of 5 wt%.

[0050] Preparation Example 2-4

[0051] Prepare a solution containing the modified MOF material according to the method of Preparation Example 2-1, except that copper nitrate is replaced with the same weight of ferric nitrate, and the other conditions are the same as those in Preparation Example 2-1, to obtain a solution containing the modified MOF material.

[0052] Example 1

[0053] S21. Immerse a high molecular weight polyethylene support layer (the number average molecular weight of the contained high molecular polymer is 30,000) in a polymerization monomer impregnation solution containing low molecular weight polyethylene (number average molecular weight of 2,000), styrene, divinylbenzene, azobisisobutyronitrile, and MOF material (obtained from Preparation Example 2-1). The mass ratio of low molecular weight polyethylene, styrene, divinylbenzene, azobisisobutyronitrile, and MOF material is 100:50:5:1:10. The total concentration of the polymerization monomer impregnation solution is 35 wt% and the solvent contained therein is toluene. After the impregnation is completed, take out the support layer from the impregnation solution and react it in a nitrogen atmosphere at a temperature of 50 °C and a pressure of 0.5 MPa for 10 h to obtain a crosslinked base film with a thickness of 10 ± 0.5 microns.

[0054] Spray the solution containing Polymer I obtained from Preparation Example 1-1 on the surface of the substrate, vacuum dry it at 60 °C for 2 h, and then peel the film layer from the surface of the substrate to obtain a cation exchange membrane with a thickness of 20 ± 0.5 microns.

[0055] Charge diallyldimethylammonium chloride, allyltrimethylammonium chloride, and potassium persulfate in a molar ratio of 1:0.01:0.001 into toluene, react at a temperature of 50 °C and a pressure of 0.5 MPa for 10 h to obtain a solution containing a copolymer. Spray the solution containing the copolymer on the surface of the substrate, vacuum dry it at 60 °C for 2 h, and then peel the film layer from the surface of the substrate to obtain an anion exchange membrane with a thickness of 20 ± 0.5 microns.

[0056] S22. Bond the cation exchange membrane and the anion exchange membrane to the upper and lower surfaces of the crosslinked base film respectively, and then hot press at a temperature of 200 °C and a pressure of 20 MPa for 60 min to obtain a crosslinked bipolar membrane, denoted as JLM-001.

[0057] Example 2

[0058] S21. Immerse a high molecular weight polyethylene support layer (the number average molecular weight of the contained high molecular polymer is 30,000) in a polymerization monomer impregnation solution containing low molecular weight polyethylene (number average molecular weight of 5,000), styrene, divinylbenzene, azobisisobutyronitrile, and MOF material (obtained from Preparation Example 2-2). The mass ratio of low molecular weight polyethylene, styrene, divinylbenzene, azobisisobutyronitrile, and MOF material is 100:80:10:5:15. The total concentration of the polymerization monomer impregnation solution is 25 wt% and the solvent contained therein is toluene. After the impregnation is completed, take out the support layer from the impregnation solution and react it in a nitrogen atmosphere at a temperature of 50 °C and a pressure of 0.5 MPa for 10 h to obtain a crosslinked base film with a thickness of 30 ± 0.5 microns.

[0059] The solution containing Polymer I obtained from Preparation Example 1-1 was sprayed onto the surface of the substrate and vacuum-dried at 60°C for 2 h. Then, the film layer was peeled off from the substrate surface to obtain a cation exchange membrane with a thickness of 5 ± 0.5 μm.

[0060] Diallyldimethylammonium chloride, allyltrimethylammonium chloride and potassium persulfate were fed into toluene at a molar ratio of 1:0.1:0.01 and reacted at a temperature of 50°C and a pressure of 0.5 MPa for 10 h to obtain a solution containing the copolymer. The solution containing the copolymer was sprayed onto the surface of the substrate and vacuum-dried at 60°C for 2 h. Then, the film layer was peeled off from the substrate surface to obtain an anion exchange membrane with a thickness of 5 ± 0.5 μm.

[0061] S22. The cation exchange membrane and the anion exchange membrane were respectively laminated to the upper and lower surfaces of the crosslinked base membrane, and then hot-pressed at a temperature of 400°C and a pressure of 5 MPa for 10 min to obtain a crosslinked bipolar membrane, denoted as JLM-002.

[0062] Example 3

[0063] S21. The high molecular weight polyethylene support layer (the number average molecular weight of the high molecular polymer contained therein is 20,000) was impregnated in a polymerization monomer impregnating solution containing low molecular weight polyethylene (number average molecular weight of 3,000), styrene, divinylbenzene, azobisisobutyronitrile and MOF material (obtained from Preparation Example 2-3). The mass ratio of low molecular weight polyethylene, styrene, divinylbenzene, azobisisobutyronitrile and MOF material is 100:60:8:2:15. The total concentration of the polymerization monomer impregnating solution is 30 wt% and the solvent contained therein is toluene. After the impregnation was completed, the support layer was taken out of the impregnating solution and reacted at a temperature of 50°C and a pressure of 0.5 MPa in a nitrogen atmosphere for 10 h to obtain a crosslinked base membrane with a thickness of 20 ± 0.5 μm.

[0064] The solution containing Polymer I obtained from Preparation Example 1-1 was sprayed onto the surface of the substrate and vacuum-dried at 60°C for 2 h. Then, the film layer was peeled off from the substrate surface to obtain a cation exchange membrane with a thickness of 10 ± 0.5 μm.

[0065] Diallyldimethylammonium chloride, allyltrimethylammonium chloride and potassium persulfate were fed into toluene at a molar ratio of 1:0.05:0.005 and reacted at a temperature of 50°C and a pressure of 0.5 MPa for 10 h to obtain a solution containing the copolymer. The solution containing the copolymer was sprayed onto the surface of the substrate and vacuum-dried at 60°C for 2 h. Then, the film layer was peeled off from the substrate surface to obtain an anion exchange membrane with a thickness of 10 ± 0.5 μm.

[0066] S22. Attach a cation exchange membrane and an anion exchange membrane to the upper and lower surfaces of the crosslinked base membrane respectively, and then perform hot pressing at a temperature of 300 °C and a pressure of 10 MPa for 30 min to obtain a crosslinked bipolar membrane, denoted as JLM-003.

[0067] Example 4

[0068] Prepare the crosslinked bipolar membrane according to the method of Example 1, except that the solution containing the modified MOF material obtained from Preparation Example 2-1 is replaced with the solution containing the modified MOF material obtained from Preparation Example 2-4 in the same weight parts, and the other conditions are the same as those in Example 1, to obtain a crosslinked bipolar membrane, denoted as JLM-004. Among them, the thickness of the cation exchange membrane is 20 ± 0.5 μm, the thickness of the crosslinked base membrane is 10 ± 0.5 μm, and the thickness of the anion exchange membrane is 20 ± 0.5 μm.

[0069] Comparative Example 1

[0070] Prepare the crosslinked bipolar membrane according to the method of Example 1, except that the solution containing Polymer Ⅰ obtained from Preparation Example 1-1 is replaced with the reference solution containing Polymer Ⅰ obtained from Comparative Preparation Example 1-1 in the same weight parts, and the other conditions are the same as those in Example 1, to obtain a reference crosslinked bipolar membrane, denoted as DJLM-001. Among them, the thickness of the cation exchange membrane is 20 ± 0.5 μm, the thickness of the crosslinked base membrane is 10 ± 0.5 μm, and the thickness of the anion exchange membrane is 20 ± 0.5 μm.

[0071] Comparative Example 2

[0072] Prepare the crosslinked bipolar membrane according to the method of Example 1, except that in the preparation process of the anion exchange membrane, diallyldimethylammonium chloride is replaced with allyltrimethylammonium chloride in the same molar amount, and the other conditions are the same as those in Example 1, to obtain a reference crosslinked bipolar membrane, denoted as DJLM-002. Among them, the thickness of the cation exchange membrane is 20 ± 0.5 μm, the thickness of the crosslinked base membrane is 10 ± 0.5 μm, and the thickness of the anion exchange membrane is 20 ± 0.5 μm.

[0073] Test Example

[0074] This test example uses a two-compartment bipolar membrane electrodialysis device. The anode plate material is a reticulated metal DSA, the cathode plate material is a reticulated titanium electrode plate, the bipolar membrane and the cation exchange membrane are BP-1 type bipolar membrane and CMX type cation exchange membrane ( CMX, manufactured by ASTOM Corporation, Japan), the membrane area is 200 cm 2 , and the membrane stack consists of 10 repeating units of B1C2 configuration.

[0075] As Figure 1As shown, a concentrated seawater solution with a NaCl concentration of 0.58 mol / L is introduced into the acid chamber inlet of the two-compartment bipolar membrane electrodialysis device, deionized water is introduced into the alkali chamber, and a 0.5 mol / L Na2SO4 solution is introduced into the electrode solution chamber. A DC power supply is turned on for constant voltage electrodialysis at 12 V. After 30 minutes, the concentration of hydrochloric acid at the acid chamber outlet and the concentration of sodium hydroxide at the alkali chamber outlet are measured. The results are shown in Table 1.

[0076] After continuously performing electrodialysis on seawater with the bipolar membrane for half a year, the concentration of hydrochloric acid at the acid chamber outlet and the concentration of sodium hydroxide at the alkali chamber outlet after the completion of electrodialysis are measured according to the above method. The results are shown in Table 1.

[0077] Table 1

[0078]

[0079] From the results of Examples 1 to 4 and Comparative Examples 1 to 2, it can be seen that using the crosslinked bipolar membrane provided by the present invention for electrolyzing seawater by the bipolar membrane electrodialysis method can continuously and efficiently obtain hydrochloric acid and sodium hydroxide. From the comparison between Example 1 and Example 4, it can be seen that when the MOF material is co-modified with Fe and Cu, it is more conducive to promoting the synthesis of hydrochloric acid and sodium hydroxide.

[0080] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention without departing from the principles and purposes of the present invention.

Claims

1. A crosslinked bipolar membrane, characterized in that, The crosslinked bipolar membrane includes a crosslinked base membrane, a cation exchange membrane, and an anion exchange membrane respectively located on both surface sides of the crosslinked base membrane; The crosslinked base membrane is prepared by the following method: impregnating a high molecular weight polyethylene support layer in a polymerization monomer impregnating solution containing low molecular weight polyethylene, styrene, divinylbenzene, an initiator, and a MOF material, and after the impregnation is completed, carrying out a polymerization reaction on the support layer under an inert atmosphere to obtain the crosslinked base membrane; The cation exchange membrane is formed of a polymer I having the structure shown in formula (1); The anion exchange membrane is formed of a polymer II, and the polymer II is a copolymer obtained by copolymerizing diallyldimethylammonium chloride and allyltrimethylammonium chloride at a molar ratio of 1:(0.01 - 0.1); The MOF material is prepared by the following method: S11. Dispersing 3,5-pyrazoledicarboxylic acid in an alkaline solution, adding aluminum chloride to the obtained dispersion and stirring until dissolved, and then heating the obtained solution at 90 - 110 °C for 10 - 48 h and then filtering, and drying the obtained precipitate to obtain a MOF support; S12. Activating the MOF support at 140 - 160 °C for 10 - 24 h, then dispersing the obtained activated MOF support, ferric nitrate, and copper nitrate in an organic solvent, and then raising the temperature to 60 - 80 °C and reacting for 10 - 48 h, and after the reaction is completed, cooling to room temperature to obtain a solution containing the MOF material.

2. The crosslinked bipolar membrane according to claim 1, wherein The thickness of the cation exchange membrane is 5 - 20 microns, the thickness of the crosslinked base membrane is 10 - 30 microns, and the thickness of the anion exchange membrane is 5 - 20 microns.

3. The crosslinked bipolar membrane according to claim 1, wherein The number average molecular weight of the high molecular weight polyethylene in the high molecular weight polyethylene support layer is 10,000 - 50,000.

4. The crosslinked bipolar membrane according to claim 1, wherein The mass ratio of low molecular weight polyethylene, styrene, divinylbenzene, initiator, and MOF material in the polymerization monomer impregnating solution is 100:(50 - 80):(5 - 10):(1 - 5):(10 - 20).

5. The crosslinked bipolar membrane according to claim 1, wherein The number average molecular weight of the low molecular weight polyethylene is 1,000 - 5,000.

6. The crosslinked bipolar membrane according to claim 1, wherein The initiator is an azo initiator.

7. The crosslinked bipolar membrane according to claim 1, wherein The conditions of the polymerization reaction include a polymerization temperature of 50 - 100 °C, a polymerization pressure of 0.1 - 0.5 MPa, and a polymerization time of 0.5 - 10 h.

8. The crosslinked bipolar membrane according to any one of claims 1 to 7, characterized in that The mass ratio of the MOF support, ferric nitrate, and copper nitrate is 1:(0.5 - 0.8):(0.1 - 0.3).

9. The crosslinked bipolar membrane according to any one of claims 1 to 7, characterized in that, The polymer I is prepared by the following method: feeding butadiene into an organic solvent for polymerization reaction, and then carrying out a thiol-ene click reaction on the obtained polybutadiene and sodium 3-(5-mercapto-1-tetrazolyl)benzenesulfonate to obtain a solution containing the polymer I.

10. The crosslinked bipolar membrane according to claim 9, characterized in that, The conditions of the polymerization reaction include a polymerization temperature of 50 - 100 °C, a polymerization pressure of 0.1 - 0.5 MPa, and a polymerization time of 0.5 - 10 h.

11. The crosslinked bipolar membrane according to claim 9, wherein, The molar ratio of butadiene to sodium 3-(5-mercapto-1-tetrazolyl)benzenesulfonate is (0.9 - 1.1):

1.

12. The crosslinked bipolar membrane according to claim 9, wherein The conditions of the thiol-ene click reaction include a temperature of 70 - 100 °C, a pressure of 0.1 - 0.5 MPa, and a time of 0.5 - 5 h.

13. The crosslinked bipolar membrane according to any one of claims 1 to 7, characterized in that, The conditions of the copolymerization reaction include a copolymerization temperature of 50 to 100 °C, a copolymerization pressure of 0.1 to 0.5 MPa, and a copolymerization time of 0.5 to 10 h.

14. The crosslinked bipolar membrane according to any one of claims 1 to 7, characterized in that, The copolymerization reaction is carried out in the presence of an inorganic peroxide initiator.

15. The preparation method of the crosslinked bipolar membrane according to any one of claims 1 to 14, characterized in that, The method includes the following steps: S21. Immerse the high molecular weight polyethylene support layer in a polymerization monomer impregnation solution containing low molecular weight polyethylene, styrene, divinylbenzene, an initiator, and a MOF material. After impregnation is completed, carry out a polymerization reaction on the support layer under an inert atmosphere to obtain a crosslinked base membrane. Feed butadiene into an organic solvent for polymerization reaction, and then carry out a thiol-ene click reaction between the obtained polybutadiene and sodium 3-(5-mercapto-1-tetrazolyl)benzenesulfonate to obtain a solution containing Polymer I. Spray the solution containing Polymer I on the surface of the substrate and dry it. Then peel the film layer from the surface of the substrate to obtain a cation exchange membrane. Feed diallyldimethylammonium chloride, allyltrimethylammonium chloride, and an inorganic peroxide initiator in a molar ratio of 1:(0.01 - 0.1):(0.001 - 0.01) into an organic solvent for copolymerization reaction to obtain a solution containing a copolymer. Spray the solution containing the copolymer on the surface of the substrate and dry it. Then peel the film layer from the surface of the substrate to obtain an anion exchange membrane. S22. Bond the cation exchange membrane and the anion exchange membrane to the upper and lower surfaces of the crosslinked base membrane respectively, and then carry out hot pressing to obtain a crosslinked bipolar membrane.

16. The preparation method of the crosslinked bipolar membrane according to claim 15, characterized in that, The conditions of the hot pressing include a hot pressing temperature of 200 to 400 °C, a hot pressing pressure of 5 to 20 MPa, and a hot pressing time of 10 to 60 min.

17. Use of the crosslinked bipolar membrane according to any one of claims 1 to 14 in the resource recovery of production wastewater containing high-concentration salts.

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