A method for preparing a monovalent anion selective amphoteric ion exchange membrane

Abstract

The invention discloses a method for preparing a monovalent anion selective amphoteric structure ion exchange membrane, comprising the following steps: (1) preparing a 2-(3-(dimethylamino)propane)-3,3-bis(4-hydroxyphenyl)isoindolinone monomer; (2) co-condensing 2-(3-(dimethylamino)propane)-3,3-bis(4-hydroxyphenyl)isoindolinone monomer, 4,4'-difluorodiphenyl sulfone monomer and 2,2'-bis(4-hydroxyphenyl)hexafluoropropane monomer to obtain a main chain amino-phenolphthalein structure polyarylethersulfone; (3) dissolving 1-bromopropane and sodium 3-bromopropane sulfonate with the main chain polyarylethersulfone obtained in the step (2) in an organic solvent to obtain a casting solution, casting the obtained casting solution on a glass plate, and achieving in-situ crosslinking at 40-200°C to obtain an amphoteric structure polyarylethersulfone ion exchange membrane.

Description

Technical Field

[0001] The invention relates to the field of macromolecular polymer materials, and in particular to a method for preparing a monovalent anion selective amphoteric structure ion exchange membrane. Background Art

[0002] As an important application field of membrane separation technology, ion selective separation involves important chemical processes such as resource recycling and reuse, energy conversion and storage, and is involved in the fields of lithium extraction from salt lakes, brine refining (chlor-alkali industry), high-salt wastewater resource utilization, flow batteries and salt difference power generation. In view of major national needs such as energy conservation and emission reduction and transformation and upgrading of traditional industries, the progress of ion separation technology is of great significance to the sustainable development of chemical industry production (Chinese J. Chem. Eng. 2017, 25, 11 1606–1615; J. Membr. Sci. 2018, 555, 429–454). Ion exchange membrane is a polymer film containing ionic groups and having the ability to selectively transmit ions in solution. Since the ion exchange membrane itself is insulated from electrons but can selectively transmit ions, it plays an irreplaceable role in many electrochemical fields and is a core component of new energy equipment (such as fuel cells, water electrolysis, flow batteries, carbon dioxide electroreduction, etc.) and important industrial processes (chlor-alkali industry, seawater desalination, wastewater treatment, diffusion dialysis, electrodialysis). Among them, electrodialysis is a relatively mature technology in the membrane separation process and has been widely used in chemical, light, metallurgical, papermaking, and pharmaceutical industries. It is particularly valued in the preparation of pure water and the treatment of "three wastes" in environmental protection.

[0003] From the perspective of molecular design, the construction of homogeneous polymer ion membranes with suitable ion transport channels and stable structures is the key to achieving monovalent and divalent anions (e.g., Cl – / SO4 2–) is an important means of separation. Among them, amphoteric ion exchange membrane is a special type of ion exchange membrane. Because it has both anion exchange groups and cation exchange groups, this type of ion exchange membrane has special uses. By regulating the number of anion and cation exchange groups and the charge ratio, the chemical microenvironment and physical microenvironment of the ion channel of the ion membrane are coordinated to construct an ion transmission channel, and the separation principle of pore size screening effect, electrostatic repulsion effect or ion hydration energy difference can be used to achieve the separation of monovalent / multivalent ions (Adv. Mater. 27 (2015) 5280–5295; J. Membr. Sci. 555 (2018) 429–454). Compared with traditional surface-modified ion exchange membranes, the ion exchange membrane obtained by uniform amphoteric structural polymers and ion crosslinking between anion / cation exchange groups presents a homogeneous microstructure, and good structural, mechanical and dimensional stability is conducive to long-term electrodialysis applications (Nanoscale 9 (2017) 2942–2958). The aggregation of positively charged groups forms ion clusters of appropriate sizes, constructing ion transfer channels of appropriate sizes; the introduction of negatively charged groups changes the microenvironment of the transfer channel, and the differences in interactions with monovalent / divalent anions of different charges can selectively penetrate monovalent anions and inhibit the penetration of divalent anions, thereby improving the screening performance of monovalent / divalent anions.

[0004] By designing the structure of the polyelectrolyte and regulating its microstructure, under appropriate conditions, an amphoteric ion exchange membrane containing anion exchange groups and cation exchange groups is constructed, and ion cross-linking is used to promote the formation of a three-dimensional network structure. At the same time, the introduction of a twisted structure increases the internal free volume of the polymer ion exchange membrane, constructs an ion transmission channel of appropriate size, and constructs an amphoteric ion exchange membrane with high monovalent ion selectivity and structural and dimensional stability. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a method for preparing a monovalent anion selective amphoteric ion exchange membrane.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] (1) Preparation of monomers:

[0008] N,N-dimethyl-1,3-propylenediamine and 3,3-bis(4-hydroxyphenyl)-3H-isobenzofuranone (phenolphthalein) were reacted under reflux at 160° C. in a nitrogen atmosphere to prepare 2-(3-(dimethylamino)propane)-3,3-bis(4-hydroxyphenyl)isoindolinone monomer represented by formula (I);

[0009]

[0010] (2) Preparation of the main chain:

[0011] The main chain polyarylethersulfone containing amino-phenolphthalein structure is obtained by solvent co-condensation of 2-(3-(dimethylamino)propane)-3,3-bis(4-hydroxyphenyl)isoindolinone monomer, 4,4'-difluorodiphenylsulfone monomer and 2,2'-bis(4-hydroxyphenyl)hexafluoropropane monomer as shown in formula (I), wherein 2-(3-(dimethylamino)propane)-3,3-bis(4-hydroxyphenyl)isoindolinone and 2,2'-bis(4-hydroxyphenyl)hexafluoropropane are The ratio of the total amount of the poly(3-(dimethylamino)propane)-3,3-bis(4-hydroxyphenyl)isoindolinone monomer to the amount of the poly(4-hydroxyphenyl)hexafluoropropane) is 1:1, the molar ratio of the 2-(3-(dimethylamino)propane)-3,3-bis(4-hydroxyphenyl)isoindolinone monomer to 2,2'-bis(4-hydroxyphenyl)hexafluoropropane is x:100-x=100%-80%:0%-20%; the number average molecular weight Mn of the poly(arylethersulfone) is 50,000-120,000.

[0012]

[0013] Among them, x: 100% - x = 100% ~ 80%: 0% ~ 20%.

[0014] (II)

[0015] (3) Preparation of amphoteric ion exchange membrane:

[0016] The polyarylethersulfone represented by formula (II) prepared in (2) is dissolved in an organic solvent and cooled to below zero degrees, and then 1-bromopropane represented by formula (III) and sodium 3-bromopropanesulfonate represented by formula (IV) are added in sequence in a mass ratio of 10:1.50-2.00:0-0.60, stirred for a certain period of time, and allowed to stand for degassing to obtain a casting solution, wherein the mass volume concentration of polyarylethersulfone in the casting solution is 3-8%; the organic solvent is one or more of DMF, DMAc, and NMP, and the obtained casting solution is poured on a glass plate, maintained at 40-200°C for 12-96h to achieve in-situ reaction and drying, and after cooling, the film is peeled off from the glass plate in water to obtain an amphoteric structure ion exchange membrane, whose structural formula is shown in formula (V) and has a thickness of 70-150μm.

[0017]

[0018]

[0019]

[0020] Among them, x:100%-x=100%~80%:0%~20%; x:y=100%:5%~20%.

[0021] (V)

[0022] Preferably, step (1) of the present invention is specifically implemented as follows: in a reaction container, N,N-dimethyl-1,3-propylenediamine and 3,3-bis(4-hydroxyphenyl)-3H-isobenzofuranone (phenolphthalein) are used, heated to reflux under a nitrogen atmosphere, maintained for 12-48 hours, and then cooled to room temperature, slowly poured into an ice-water mixture, and then dilute hydrochloric acid is added dropwise to form a white precipitate, the precipitate is washed 3 to 4 times with a mixture of ethanol and water (ethanol: water = 1:2), and the precipitate is vacuum dried at 30° C. for 24 hours to obtain a 2-(3-(dimethylamino)propane)-3,3-bis(4-hydroxyphenyl)isoindolinone monomer represented by formula (I).

[0023] As a further preference, in step (1), the molar ratio of the N,N-dimethyl-1,3-propylenediamine to 3,3-bis(4-hydroxyphenyl)-3H-isobenzofuranone (phenolphthalein) is 1.0-2.5:1, most preferably 1.2:1.

[0024] As a further preference, in step (1), the dilute hydrochloric acid solution is a hydrochloric acid aqueous solution with a pH of 0-1 (most preferably pH = 0).

[0025] As a further preference, in step (1), the separation and purification is carried out as follows: under a nitrogen atmosphere, heating to reflux, maintaining for 12-48 hours, and then cooling to room temperature, slowly pouring into an ice-water mixture, and then adding dilute hydrochloric acid dropwise to produce a white precipitate, the precipitate is washed 3 to 4 times with a mixture of ethanol and water (ethanol: water = 1:2), and the precipitate is vacuum dried at 30-80°C (more preferably 60°C) for 6-24 hours (more preferably 24 hours).

[0026] Preferably, in step (2), the molar ratio of 2-(3-(dimethylamino)propane)-3,3-bis(4-hydroxyphenyl)isoindolinone to 2,2'-bis(4-hydroxyphenyl)hexafluoropropane is 100% to 80%:0% to 20%, most preferably 85% to 80%:5% to 20%.

[0027] Preferably, step (2) of the present invention is specifically implemented as follows: 4,4'-difluorodiphenyl sulfone, 2-(3-(dimethylamino)propane)-3,3-bis(4-hydroxyphenyl)isoindolinone and 2,2'-bis(4-hydroxyphenyl)hexafluoropropane monomers, a polar aprotic solvent B, a salt-forming agent potassium carbonate and a water-carrying agent are added to a reaction container, and the mixture is stirred and reacted at 100 to 180° C. for 3 to 24 hours under nitrogen protection. After the reaction is completed, the main chain polyarylethersulfone is obtained by separation and drying.

[0028] As a further preference, in step (2), the polar aprotic solvent B is at least one of N,N-dimethylacetamide, N,N-dimethylformamide, and N-methylpyrrolidone.

[0029] As a further preference, in step (2), the mass dosage of the salt-forming agent potassium carbonate is 4.0-6.5 g / 20 mmol based on the amount of 4,4'-difluorodiphenyl sulfone.

[0030] As a further preference, the water-carrying agent is toluene, and the volume ratio of the toluene to the polar aprotic solvent B is 0.2-0.7:1.

[0031] As a further preference, in step (2), the polar solvent C is one or more of dimethylformamide (DMF), dimethylacetamide (DMAc), N-methylpyrrolidone (NMP), and dimethyl sulfoxide (DMSO).

[0032] As further preferred, the co-condensation reaction conditions are: react at 120-155°C (more preferably 155°C) for 3-5h (more preferably 4h), and then react at 155-165°C (more preferably 165°C) for 2-4h (more preferably 3h).

[0033] As a further preference, in step (2), the separation and drying are carried out as follows: after the reaction solution is cooled to room temperature, it is slowly poured into ethanol and stirred to precipitate, then the precipitate is collected by filtration, washed several times with ethanol and water, and then vacuum dried at 60-120°C for 10-48h to obtain the main chain polyarylethersulfone.

[0034] Preferably, in step (3), the mass ratio of polyarylethersulfone, 1-bromopropane and sodium 3-bromopropanesulfonate is 10:1.50-2.00:0-0.60.

[0035] As a further preference, in step (3), the mass ratio of polyarylethersulfone, 1-bromopropane and sodium 3-bromopropanesulfonate is 10:1.60-1.80:0.10-0.20.

[0036] Preferably, in step (3), the mass volume concentration of polyarylethersulfone in the casting solution is 5%.

[0037] Preferably, in step (3), the reaction conditions are: reacting at 80° C. for 18-36 hours.

[0038] As a further preference, in step (3), the reaction conditions are: reacting at 80° C. for 24 h.

[0039] The amphoteric ion exchange membrane prepared by the invention has the advantages of good ion conductivity, good dimensional stability, high monovalent anion permeation selectivity and the like, and has broad application prospects, especially in the field of electrodialysis applications.

[0040] Compared with the prior art, the advantages of the present invention are:

[0041] (1) The monovalent anion selective amphoteric ion exchange membrane of the present invention contains both positively charged ammonium salt anion exchange groups and sulfonic acid cation exchange groups. Ionic crosslinking between the anion / cation exchange groups can increase the compactness of the ion exchange membrane matrix and also promote the formation of a three-dimensional network structure, so that the ion exchange membrane exhibits a uniform microscopic morphology and good structural, mechanical and dimensional stability.

[0042] (2) The monovalent anion selective amphoteric ion exchange membrane of the present invention contains both a rigid aromatic main chain structure and a flexible fatty side chain structure. During the membrane formation process, the hydrophobic main chain and the hydrophilic side chain self-aggregate to form a "hydrophobic aromatic region microphase" and a "hydrophilic ion cluster microphase", respectively, and the introduced twisted unit segment structure tends to inhibit the stacking between chains and promote the formation of a larger free volume, which is conducive to the formation of an "ion channel" of appropriate size.

[0043] (3) The monovalent anion selective amphoteric ion exchange membrane of the present invention is beneficial to the "plasticization effect" of the polymer matrix in the membrane process due to ionic crosslinking, and a certain amount of negatively charged sulfonate groups and monovalent / multivalent anions (such as Cl, – / SO4 2– ) helps to inhibit the penetration of multivalent ions in the ion exchange membrane and improve the selectivity of the membrane for monovalent anions. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is the nuclear magnetic spectrum and result diagram of the 2-(3-(dimethylamino)propane)-3,3-bis(4-hydroxyphenyl)isoindolinone monomer prepared in Example 1 of the present invention.

[0045] Figure 2 This is a photograph of the monovalent anion selective amphoteric ion exchange membrane prepared in Example 6 of the present invention. DETAILED DESCRIPTION

[0046] To further illustrate the technical solution of the present invention, the preferred implementation scheme of the present invention is described below in conjunction with specific examples, but it should be understood that these descriptions are only to further illustrate the features and advantages of the present invention, rather than to limit the claims of the present invention.

[0047] Embodiment 1:

[0048] Preparation of monomer: Weigh 40 g (18 mmol) of N,N'-dimethyl-1,3-propylenediamine into a reaction container, then add 20 g (18 mmol) of 3,3-bis(4-hydroxyphenyl)-3H-isobenzofuranone (phenolphthalein), heat to reflux under nitrogen atmosphere, maintain for 24 h, then cool to room temperature, slowly pour into an ice-water mixture, then add 0.1 M dilute hydrochloric acid dropwise to neutralize, a white precipitate appears, the precipitate is washed three times with a mixture of ethanol and water (ethanol: water = 1:2), and the precipitate is vacuum dried at 30°C for 24 h to obtain 2-(3-(dimethylamino)propane)-3,3-bis(4-hydroxyphenyl)isoindolinone monomer shown in formula (I).

[0049] Preparation of the main chain: 5.0804 g (20 mmol) of 4,4'-difluorodiphenyl sulfone and 8.0498 g (20 mmol) of 2-(3-(dimethylamino)propane)-3,3-di(4-hydroxyphenyl)isoindolinone monomers were added to a 250 mL three-necked round-bottom flask equipped with a water separator, DMAc (60 mL) was used as the solvent, and 5.6 g of K2CO3 and 45 mL of toluene were added as a catalyst and a water carrier, respectively. In a N2 atmosphere, the reaction was carried out at 155°C for 4 h, and then at 165°C for 12 h. When the solution was cooled to room temperature, it was poured into 300 mL of ethanol and flocculated to obtain a precipitate under high-speed stirring. After separation by suction filtration, a brown solid was obtained, which was repeatedly washed with ethanol and water for several times and dried in vacuo at 80°C for 20 hours to obtain 10.6 grams of polyarylethersulfone having an alternating structure of 4,4'-difluorodiphenylsulfone and 2-(3-(dimethylamino)propane)-3,3-di(4-hydroxyphenyl)isoindolinone, with a molecular weight of Mn=78200.

[0050] Preparation of anion exchange membrane: Weigh 10 grams of poly(arylethersulfone) into a round-bottom three-necked flask, dissolve in 60 mL of NMP solvent, and stir magnetically at 80°C until completely dissolved, then add 1.9924 grams of 1-bromopropane, and stir to obtain a casting solution; degas the casting solution, and then pour the degassed casting solution into a clean glass mold, and dry it at 80°C for 24 hours to form a film to obtain a poly(arylethersulfone) anion exchange membrane.

[0051] The thickness, ion exchange capacity, tensile strength and swelling rate of the prepared monovalent anion selective anion exchange membrane were experimentally tested using the national standard method; the surface resistance, migration number, permeation selectivity and ion flux of the ion exchange membrane were tested using a homemade device. The results are shown in Table 1. (For specific test methods, please refer to the literature reports: Journal of Membrane Science 574 (2019) 181–195; Journal of Membrane Science 577 (2019) 153–164).

[0052] Embodiment 2:

[0053] Preparation of monomer: The same preparation process as in Example 1 was adopted.

[0054] Preparation of the main chain: The same preparation process as in Example 1 was adopted, except that 5.0804 g (20 mmol) of 4,4'-difluorodiphenyl sulfone, 7.2448 g (18 mmol) of 2-(3-(dimethylamino)propane)-3,3-bis(4-hydroxyphenyl)isoindolinone monomer and 0.6725 g (2 mmol) of 2,2'-bis(4-hydroxyphenyl)hexafluoropropane monomer were added, and 10.2 g of 2-(3-(dimethylamino)propane)-3,3-bis(4-hydroxyphenyl)isoindolinone content of 90% was obtained by reaction, and its molecular weight was tested to be 76800 in number average molecular weight.

[0055] Preparation of anion exchange membrane: The same preparation process as in Example 1 was adopted, except that 1.8203 g of 1-bromopropane was added, and the polyarylethersulfone anion exchange membrane was obtained through reaction and drying.

[0056] The thickness, ion exchange capacity, tensile strength and swelling rate of the prepared monovalent anion selective anion exchange membrane were experimentally tested using the national standard method; the surface resistance, migration number, permeation selectivity and ion flux of the ion exchange membrane were tested using a homemade device. The results are shown in Table 1. (For specific test methods, please refer to the literature reports: Journal of Membrane Science 574 (2019) 181–195; Journal of Membrane Science 577 (2019) 153–164).

[0057] Embodiment 3:

[0058] Preparation of monomer: The same preparation process as in Example 1 was adopted.

[0059] Preparation of the main chain: The same preparation process as in Example 1 was adopted, except that 5.0804 g (20 mmol) of 4,4'-difluorodiphenyl sulfone, 6.4398 g (16 mmol) of 2-(3-(dimethylamino)propane)-3,3-bis(4-hydroxyphenyl)isoindolinone monomer and 1.3449 g (4 mmol) of 2,2'-bis(4-hydroxyphenyl)hexafluoropropane monomer were added, and 11.3 g of 2-(3-(dimethylamino)propane)-3,3-bis(4-hydroxyphenyl)isoindolinone content of 80% was obtained by reaction, and its molecular weight was tested to be 89700 in number average molecular weight.

[0060] Preparation of anion exchange membrane: The same preparation process as in Example 1 was adopted, except that 1.6358 g of 1-bromopropane was added, and an anion exchange membrane was obtained after reaction and drying.

[0061] The thickness, ion exchange capacity, tensile strength and swelling rate of the prepared monovalent anion selective anion exchange membrane were experimentally tested using the national standard method; the surface resistance, migration number, permeation selectivity and ion flux of the ion exchange membrane were tested using a homemade device. The results are shown in Table 1. (For specific test methods, please refer to the literature reports: Journal of Membrane Science 574 (2019) 181–195; Journal of Membrane Science 577 (2019) 153–164).

[0062] Embodiment 4:

[0063] Preparation of monomer: The same preparation process as in Example 1 was adopted.

[0064] Preparation of the main chain: The same preparation process as in Example 1 was adopted.

[0065] Preparation of amphoteric ion exchange membrane: The same preparation process as in Example 1 was adopted, except that 10.0 g of polyarylethersulfone was dissolved in an organic solvent and then cooled to minus 10°C, and then 1.8928 g of 1-bromopropane and 0.1823 g of sodium 3-bromopropane sulfonate were added in sequence, and the amphoteric ion exchange membrane was obtained after reaction and drying.

[0066] The thickness, ion exchange capacity, tensile strength and swelling rate of the prepared monovalent anion selective amphoteric ion exchange membrane were experimentally tested using the national standard method; the surface resistance, migration number, permeation selectivity and ion flux of the ion exchange membrane were tested using a homemade device. The results are shown in Table 1. (For specific test methods, please refer to the literature reports: Journal of Membrane Science 574 (2019) 181–195; Journal of Membrane Science 577 (2019) 153–164).

[0067] Embodiment 5:

[0068] Preparation of monomer: The same preparation process as in Example 1 was adopted.

[0069] Preparation of the main chain: The same preparation process as in Example 2 was adopted.

[0070] Preparation of amphoteric ion exchange membrane: The same preparation process as in Example 4 was adopted, except that 1.7292 g of 1-bromopropane and 0.1665 g of sodium 3-bromopropane sulfonate were added, and an amphoteric ion exchange membrane was obtained after reaction and drying.

[0071] The thickness, ion exchange capacity, tensile strength and swelling rate of the prepared monovalent anion selective amphoteric ion exchange membrane were experimentally tested using the national standard method; the surface resistance, migration number, permeation selectivity and ion flux of the ion exchange membrane were tested using a homemade device. The results are shown in Table 1. (For specific test methods, please refer to the literature reports: Journal of Membrane Science 574 (2019) 181–195; Journal of Membrane Science 577 (2019) 153–164).

[0072] Embodiment 6:

[0073] Preparation of monomer: The same preparation process as in Example 1 was adopted.

[0074] Preparation of the main chain: The same preparation process as in Example 3 was adopted.

[0075] Preparation of amphoteric ion exchange membrane: The same preparation process as in Example 4 was adopted, except that 1.5540 g of 1-bromopropane and 0.1496 g of sodium 3-bromopropane sulfonate were added, and an amphoteric ion exchange membrane was obtained after reaction and drying.

[0076] The thickness, ion exchange capacity, tensile strength and swelling rate of the prepared monovalent anion selective amphoteric ion exchange membrane were experimentally tested using the national standard method; the surface resistance, migration number, permeation selectivity and ion flux of the ion exchange membrane were tested using a homemade device. The results are shown in Table 1. (For specific test methods, please refer to the literature reports: Journal of Membrane Science 574 (2019) 181–195; Journal of Membrane Science 577 (2019) 153–164).

[0077] Embodiment 7:

[0078] Preparation of monomer: The same preparation process as in Example 1 was adopted.

[0079] Preparation of the main chain: The same preparation process as in Example 1 was adopted.

[0080] Preparation of amphoteric ion exchange membrane: The same preparation process as in Example 4 was adopted, except that 1.7932 g of 1-bromopropane and 0.3645 g of sodium 3-bromopropane sulfonate were added, and an amphoteric ion exchange membrane was obtained after reaction and drying.

[0081] The thickness, ion exchange capacity, tensile strength and swelling rate of the prepared monovalent anion selective amphoteric ion exchange membrane were experimentally tested using the national standard method; the surface resistance, migration number, permeation selectivity and ion flux of the ion exchange membrane were tested using a homemade device. The results are shown in Table 1. (For specific test methods, please refer to the literature reports: Journal of Membrane Science 574 (2019) 181–195; Journal of Membrane Science 577 (2019) 153–164).

[0082] Embodiment 8:

[0083] Preparation of monomer: The same preparation process as in Example 1 was adopted.

[0084] Preparation of the main chain: The same preparation process as in Example 2 was adopted.

[0085] Preparation of amphoteric ion exchange membrane: The same preparation process as in Example 4 was adopted, except that 1.6382 g of 1-bromopropane and 0.3330 g of sodium 3-bromopropane sulfonate were added, and an amphoteric ion exchange membrane was obtained after reaction and drying.

[0086] The thickness, ion exchange capacity, tensile strength and swelling rate of the prepared monovalent anion selective amphoteric ion exchange membrane were experimentally tested using the national standard method; the surface resistance, migration number, permeation selectivity and ion flux of the ion exchange membrane were tested using a homemade device. The results are shown in Table 1. (For specific test methods, please refer to the literature reports: Journal of Membrane Science 574 (2019) 181–195; Journal of Membrane Science 577 (2019) 153–164).

[0087] Embodiment 9:

[0088] Preparation of monomer: The same preparation process as in Example 1 was adopted.

[0089] Preparation of the main chain: The same preparation process as in Example 3 was adopted.

[0090] Preparation of amphoteric ion exchange membrane: The same preparation process as in Example 4 was adopted, except that 1.4722 g of 1-bromopropane and 0.2993 g of sodium 3-bromopropane sulfonate were added, and an amphoteric ion exchange membrane was obtained after reaction and drying.

[0091] The thickness, ion exchange capacity, tensile strength and swelling rate of the prepared monovalent anion selective amphoteric ion exchange membrane were experimentally tested using the national standard method; the surface resistance, migration number, permeation selectivity and ion flux of the ion exchange membrane were tested using a homemade device. The results are shown in Table 1. (For specific test methods, please refer to the literature reports: Journal of Membrane Science 574 (2019) 181–195; Journal of Membrane Science 577 (2019) 153–164).

[0092] Embodiment 10:

[0093] Preparation of monomer: The same preparation process as in Example 1 was adopted.

[0094] Preparation of the main chain: The same preparation process as in Example 1 was adopted.

[0095] Preparation of amphoteric ion exchange membrane: The same preparation process as in Example 4 was adopted, except that 1.6936 g of 1-bromopropane and 0.5468 g of sodium 3-bromopropane sulfonate were added, and an amphoteric ion exchange membrane was obtained after reaction and drying.

[0096] The thickness, ion exchange capacity, tensile strength and swelling rate of the prepared monovalent anion selective amphoteric ion exchange membrane were experimentally tested using the national standard method; the surface resistance, migration number, permeation selectivity and ion flux of the ion exchange membrane were tested using a homemade device. The results are shown in Table 1. (For specific test methods, please refer to the literature reports: Journal of Membrane Science 574 (2019) 181–195; Journal of Membrane Science 577 (2019) 153–164).

[0097] Embodiment 11:

[0098] Preparation of monomer: The same preparation process as in Example 1 was adopted.

[0099] Preparation of the main chain: The same preparation process as in Example 2 was adopted.

[0100] Preparation of amphoteric ion exchange membrane: The same preparation process as in Example 4 was adopted, except that 1.5472 g of 1-bromopropane and 0.4996 g of sodium 3-bromopropane sulfonate were added, and an amphoteric ion exchange membrane was obtained after reaction and drying.

[0101] The thickness, ion exchange capacity, tensile strength and swelling rate of the prepared monovalent anion selective amphoteric ion exchange membrane were experimentally tested using the national standard method; the surface resistance, migration number, permeation selectivity and ion flux of the ion exchange membrane were tested using a homemade device. The results are shown in Table 1. (For specific test methods, please refer to the literature reports: Journal of Membrane Science 574 (2019) 181–195; Journal of Membrane Science 577 (2019) 153–164).

[0102] Embodiment 12:

[0103] Preparation of monomer: The same preparation process as in Example 1 was adopted.

[0104] Preparation of the main chain: The same preparation process as in Example 3 was adopted.

[0105] Preparation of amphoteric ion exchange membrane: The same preparation process as in Example 4 was adopted, except that 1.3904 g of 1-bromopropane and 0.4489 g of sodium 3-bromopropane sulfonate were added, and an amphoteric ion exchange membrane was obtained after reaction and drying.

[0106] The thickness, ion exchange capacity, tensile strength and swelling rate of the prepared monovalent anion selective amphoteric ion exchange membrane were experimentally tested using the national standard method; the surface resistance, migration number, permeation selectivity and ion flux of the ion exchange membrane were tested using a homemade device. The results are shown in Table 1. (For specific test methods, please refer to the literature reports: Journal of Membrane Science 574 (2019) 181–195; Journal of Membrane Science 577 (2019) 153–164).

[0107]

[0108] Table 1.

Claims

1. A method for preparing a monovalent anion selective amphoteric ion exchange membrane, comprising the following steps: (1) Preparation of monomers: N,N-dimethyl-1,3-propylenediamine and 3,3-bis(4-hydroxyphenyl)-3H-isobenzofuranone were reacted under reflux at 160° C. in a nitrogen atmosphere to prepare a 2-(3-(dimethylamino)propane)-3,3-bis(4-hydroxyphenyl)isoindolinone monomer represented by formula (I); (2) Preparation of the main chain: The main chain polyarylethersulfone containing amino-phenolphthalein structure shown in formula (II) is obtained by solvent co-condensation of 2-(3-(dimethylamino)propane)-3,3-bis(4-hydroxyphenyl)isoindolinone monomer, 4,4'-difluorodiphenylsulfone monomer and 2,2'-bis(4-hydroxyphenyl)hexafluoropropane monomer, wherein 2-(3-(dimethylamino)propane)-3,3-bis(4-hydroxyphenyl)isoindolinone and 2,2'-bis(4-hydroxyphenyl)hexafluoropropane monomer are esterified with 2-(3-(dimethylamino)propane)-3,3-bis(4-hydroxyphenyl)isoindolinone monomer, 4,4'-difluorodiphenylsulfone monomer and 2,2'-bis(4-hydroxyphenyl)hexafluoropropane monomer. The total amount of (4-hydroxyphenyl) hexafluoropropane and the amount of 4,4'-difluorodiphenyl sulfone is 1:1, the molar ratio of the 2-(3-(dimethylamino)propane)-3,3-bis(4-hydroxyphenyl)isoindolinone monomer and 2,2'-bis(4-hydroxyphenyl)hexafluoropropane is m:100-m=85%-80%:5%-20%; the number average molecular weight Mn of the polyarylethersulfone is 50000-120000; (3) Preparation of amphoteric ion exchange membrane: The polyarylethersulfone represented by formula (II) prepared in step (2) is dissolved in an organic solvent and cooled to below zero, and then 1-bromopropane represented by formula (III) and sodium 3-bromopropanesulfonate represented by formula (IV) are added in sequence according to a mass ratio of 10:1.60-1.80:0.10-0.20, stirred for a certain period of time, and allowed to stand for degassing to obtain a casting solution, wherein the mass volume concentration of polyarylethersulfone in the casting solution is 3-8%; the organic solvent is one or more of DMF, DMAc, and NMP, and the obtained casting solution is poured on a glass plate, maintained at 40-200° C. for 12-96 hours to achieve in-situ reaction and drying, and after cooling, the film is peeled off from the glass plate in water to obtain an amphoteric structure ion exchange membrane, whose structural formula is shown in formula (V) and whose thickness is 70-150 μm; Among them, x:100%-x=100%~80%:0%~20%; x:y=100%:5%~20%.

2. The preparation method according to claim 1, characterized in that: Step (1) is specifically implemented as follows: In a reaction container, N,N-dimethyl-1,3-propylenediamine and 3,3-bis(4-hydroxyphenyl)-3H-isobenzofuranone are used, wherein the molar ratio of the N,N-dimethyl-1,3-propylenediamine to the 3,3-bis(4-hydroxyphenyl)-3H-isobenzofuranone is 1.0-2.5:1, and the mixture is heated to reflux under a nitrogen atmosphere for 12-48 hours, then cooled to room temperature, slowly poured into an ice-water mixture, and then diluted hydrochloric acid is added dropwise to produce a white precipitate. The precipitate is washed 3 to 4 times with a mixture of ethanol and water, and the precipitate is vacuum dried at 30-80° C. for 6-24 hours to obtain a 2-(3-(dimethylamino)propane)-3,3-bis(4-hydroxyphenyl)isoindolinone monomer represented by formula (I).

3. The preparation method according to claim 2, characterized in that: In step (1), the dilute hydrochloric acid solution is a hydrochloric acid aqueous solution with a pH of 0-1.

4. The preparation method according to claim 1, characterized in that: Step (2) is specifically implemented as follows: 4,4'-difluorodiphenyl sulfone, 2-(3-(dimethylamino)propane)-3,3-bis(4-hydroxyphenyl)isoindolinone and 2,2'-bis(4-hydroxyphenyl)hexafluoropropane monomers, polar aprotic solvent B, salt-forming agent potassium carbonate and water-carrying agent are added into a reaction container, and the mixture is stirred at 100-180° C. for 3-24 hours under nitrogen protection. After the reaction is completed, the main chain polyarylethersulfone is obtained by separation and drying; the polar aprotic solvent B is at least one of N,N-dimethylacetamide, N,N-dimethylformamide and N-methylpyrrolidone; the mass amount of the salt-forming agent potassium carbonate is 4.0-6.5 g / 20 mmol based on the amount of 4,4'-difluorodiphenyl sulfone; the water-carrying agent is toluene, and the volume ratio of toluene to the polar aprotic solvent B is 0.2-0.7:

1.

5. The preparation method according to claim 1, characterized in that: The co-condensation reaction conditions are: reaction at 120-155°C for 3-5h, and then reaction at 155-165°C for 2-4h.

6. The preparation method according to claim 4, characterized in that: In step (2), the separation and drying are carried out as follows: after the reaction solution is cooled to room temperature, it is slowly poured into ethanol and stirred to precipitate, and then the precipitate is collected by filtration, washed with ethanol and water several times, and then vacuum dried at 60-120° C. for 10-48 hours to obtain the main chain polyarylethersulfone.

7. The preparation method according to claim 1, characterized in that: In step (3), the mass volume concentration of polyarylethersulfone in the casting solution is 5%.

8. The preparation method according to claim 1, characterized in that: In step (3), the reaction conditions are: reacting at 80° C. for 18-36 hours.

Images