A method for preparing a monovalent / divalent cation separation ion exchange membrane
By introducing a rigid aromatic backbone and a flexible aliphatic side chain structure into the cation exchange membrane, combined with the recognition function of crown ether molecules, the problem of reliance on imports for mono/divalent cation separation membranes in the prior art has been solved, and a highly efficient ion selective separation effect has been achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-04-17
- Publication Date
- 2026-03-31
AI Technical Summary
In the existing technology, high-performance mono/divalent selective separation membranes rely on imports, and existing methods are difficult to achieve efficient separation of mono/divalent cations.
A nanoscale micro-phase separation structure is formed by using a rigid aromatic hydrophobic backbone and a flexible aliphatic side chain. Crown ether molecules are introduced to provide specific recognition function. By adjusting the types of cation exchange groups on the side chains, the cation mobility and ion exchange equilibrium constant are changed, which promotes the transport of monovalent cations and inhibits the passage of divalent cations.
The prepared cation exchange membrane has good ion conductivity and high selectivity, making it particularly suitable for electrodialysis to achieve efficient separation of monovalent and divalent cations.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of polymer separation membrane materials, specifically to a method for preparing an ion exchange membrane for separating monovalent / divalent cations, belonging to the field of membrane technology. Background Technology
[0002] Electrodialysis, as an electrically driven membrane separation technology, uses a direct current electric field to selectively permeate anions / cations through an ion exchange membrane. It has been widely applied to various monovalent / divalent ions (e.g., Na+). + / Mg 2+ Li + / Mg 2+ Cl – SO4 2– The separation of monovalent and divalent ions has become the most representative ion separation membrane technology. However, to date, China still relies on imports for high-performance monovalent / divalent selective separation membranes (such as Neosepta CMS, Neosepta ACS, Aciplex K-192, and Aciplex A-192). To improve the selectivity of monovalent / divalent ion exchange membranes, various methods have been adopted, including chemical crosslinking, surface modification, polymer blending (or organic-inorganic hybridization), and ion channel construction (Desalination. 458 (2019) 25–33). To meet the actual needs of industry, the research and development of novel monovalent / divalent cation selective separation membranes with high selectivity for separating ions of the same valence state are of great practical significance.
[0003] Based on this, a rigid aromatic hydrophobic backbone was constructed, and flexible aliphatic side chains and hydrophilic groups were introduced onto the backbone. The hydrophilic groups and hydrophobic segments aggregated into nanoscale micro-phase separation structures to form ion transport channels. Crown ether molecules with specific recognition functions for specific metal ions were introduced onto the polymer backbone, providing new ion channels for specific metal cations. Adjusting the types of cation exchange groups on the side chains altered the migration ratio between cations and the ion exchange equilibrium constant. The constructed microstructure facilitated the transport of monovalent cations while inhibiting the passage of divalent cations, thus achieving highly efficient separation of monovalent and divalent cations. Summary of the Invention
[0004] To address the aforementioned technical problems in the prior art, this invention provides a method for preparing a cation exchange membrane for separating monovalent / divalent ions, employing the following technical solution:
[0005] (1) Weigh a certain amount of catechol, LiOH, 1,3-dibromopropane and acetonitrile, heat to reflux under N2 atmosphere; after the reaction, cool to room temperature, adjust pH to weak acidity, and rotary evaporate to obtain powdered intermediate 1 as shown in formula (Ⅰ);
[0006]
[0007] (2) Weigh a certain amount of epichlorohydrin, LiOH, and intermediate 1 obtained in step (1) and dissolve them in deionized water. Heat and maintain the mixture under N2 atmosphere for several hours. After the reaction, cool to room temperature and filter to obtain powdered intermediate 2 as shown in formula (II).
[0008]
[0009] (3) Weigh a certain amount of 1-bromopropane / 1-bromopentane / 1-bromoheptane, NaH, and intermediate 2 obtained in step (2) and dissolve them in a polar solvent. Stir at room temperature under N2 atmosphere for 20 h. After the reaction, rotary evaporate to obtain Li as shown in formula (III). + Imprints DB14C4-C3 / DB14C4-C5 / DB14C4-C7;
[0010]
[0011] (4) Weigh a certain amount of DB14C4-C3 / DB14C4-C5 / DB14C4-C7 obtained in step (3), glacial acetic acid and Eaton reagent, heat and maintain under N2 atmosphere for several hours; after the reaction, cool to room temperature, wash three times with CH2Cl2 and 5% NaOH aqueous solution, dry the organic phase with MgSO4, and rotary evaporate to obtain the intermediate product DABC-1-C3 / DABC-1-C5 / DABC-1-C7 as shown in formula (IV);
[0012]
[0013] (5) Weigh a certain amount of m-chlorobenzoic acid, Na2HPO4, and the DABC-1-C3 / DABC-1-C5 / DABC-1-C7 obtained in step (4) and dissolve them in CH2Cl2. Stir at room temperature under N2 atmosphere for several hours. After the reaction, rotary evaporate to obtain crude product. Dissolve crude product in CH2Cl2 and extract three times with NaOH aqueous solution. Dry the organic phase with MgSO4 and rotary evaporate to obtain intermediate product DABC-2-C3 / DABC-2-C5 / DABC-2-C7 as shown in formula (V).
[0014]
[0015] (6) Weigh a certain amount of DABC-2-C3 / DABC-2-C5 / DABC-2-C7 obtained in step (5) and dissolve it in a mixed solution of methanol and CH2Cl2. Slowly add a methanol solution of NaOH with a mass volume fraction of 6% and stir at room temperature for several hours under N2 atmosphere. After the reaction, neutralize the reaction with HCl to obtain a solid crude product. Filter the solid and wash it with methanol. Dry it under vacuum to obtain the product DHBC-OH-C3 / DHBC-OH-C5 / DHBC-OH-C7 as shown in formula (VI).
[0016]
[0017] (7) Weigh a certain amount of DHBC-OH-C3 / DHBC-OH-C5 / DHBC-OH-C7, 4,4'-difluorodiphenyl sulfone monomers and 2,2'-bis(3-amino-4-hydroxyphenyl)hexafluoropropane, dissolve them in a high-boiling-point polar aprotic solvent, use potassium carbonate as a salt-forming agent and toluene as a dehydrating agent, and react at 100℃~180℃ for 3~24 hours under nitrogen protection. After the reaction is completed, separate and dry to obtain polyarylene ether sulfone copolymer with amino groups and crown ether structures in the main chain. The substance has a molecular weight of 30,000 to 60,000. In formula (V), x and y represent the molar percentages of the two chains as x% and y%, respectively, and x+y=100; where x=1~100 and y=1~100; and the molar ratio of 2,2'-bis(3-amino4-hydroxyphenyl)hexafluoropropane, DHBC-OH-C3 / DHBC-OH-C5 / DHBC-OH-C7 is 0~40%:100~60%, and its chemical structure is shown in formula (VII).
[0018]
[0019] (8) Weigh out a certain amount of 4-bromobutanesulfonic acid / 5-bromopentanoic acid / 4-bromobutylphosphonic acid and the amino-containing polyarylene sulfone obtained in step (7), dissolve them in DMF, and under nitrogen protection, add the former dropwise to the latter. Stir for 3 to 24 hours at 20℃~90℃. After cooling to room temperature, precipitate in isopropanol, and obtain functionalized polyarylene sulfone by washing and vacuum drying. Its chemical structure is shown in formula (VIII).
[0020]
[0021] (9) The functionalized polyarylether sulfone is dissolved in an organic solvent and allowed to stand to remove bubbles to obtain a casting solution. The mass volume concentration of the functionalized polyarylether sulfone in the casting solution is 3-8%. The casting solution is coated on a clean glass plate and vacuum dried at 40℃-150℃ for 3-24 hours to obtain a functionalized polyarylether sulfone cation exchange membrane.
[0022] Preferably, the reaction temperature in step (1) is 80-120°C and the reaction time is 10-24h, more preferably 100°C and 20h.
[0023] Preferably, the pH value adjusted in step (1) is 2 to 5, and more preferably pH = 4.
[0024] Preferably, the reaction temperature in step (2) is 30-80°C and the reaction time is 10-24h, more preferably 50°C and 10h.
[0025] Preferably, the polar solvent in step (3) is one or more of tetrahydrofuran, N-methylpyrrolidone, and N,N-dimethylformamide, and more preferably tetrahydrofuran.
[0026] Preferably, the reaction temperature in step (4) is 30-80°C and the reaction time is 10-24h, more preferably 50°C and 20h.
[0027] Preferably, the NaOH solution in step (5) has a mass-volume concentration of 3-8%, and more preferably 5%.
[0028] Preferably, the reaction time in step (6) is 10 to 24 hours, and the pH of the HCl solution is 0 to 4. More preferably, it is 24 hours and the pH is 1.
[0029] Preferably, the molar ratio of 2,2'-bis(3-amino-4-hydroxyphenyl)hexafluoropropane to DHBC-OH-C3 / DHBC-OH-C5 / DHBC-OH-C7 in step (7) is 20%:80%, i.e., x:y = 20%:80%.
[0030] Preferably, the high-boiling-point polar aprotic solvent in step (7) is N-methylpyrrolidone, and the polycondensation reaction conditions are 155°C for 4 hours, then increased to 165°C for 3 hours.
[0031] As a preferred embodiment, in step (8), the mixture is stirred for 3 to 24 hours at 20°C to 90°C, filtered, and the filtrate is precipitated in ethyl acetate, diethyl ether, or isopropanol. After precipitation, it is dried under vacuum at 60°C to 120°C, and more preferably at 110°C.
[0032] Preferably, the mass-volume concentration of polyarylether sulfone in the casting solution in step (9) is 5%, and the reaction conditions are: reaction at 80°C for 18–36 h.
[0033] The cation exchange membrane prepared by this invention has advantages such as good ion conductivity, good dimensional stability, and high selectivity for monovalent / divalent ion permeation, and has broad application prospects, especially in the field of electrodialysis.
[0034] Compared with the prior art, the advantages of this invention are:
[0035] (1) The cation exchange membrane for separating monovalent / divalent ions described in this invention contains both a rigid aromatic backbone structure and a flexible aliphatic side chain structure with hydrophilic cation exchange groups. During the membrane formation process, the hydrophobic backbone and hydrophilic side chains self-aggregate to form a "hydrophobic aromatic microphase" and a "hydrophilic ion cluster microphase", respectively, which helps to form ion channels of suitable size.
[0036] (2) The cation exchange membrane for separating monovalent / divalent ions described in this invention introduces different aliphatic side chains onto the polymer backbone. The different types of cation exchange groups on the side chains interact with monovalent / divalent cations (e.g., Li) that have the same charge but different charges. + / Mg 2+ The difference in electrostatic interaction between cations leads to changes in the mobility ratio between cations and the ion exchange equilibrium constant, thereby promoting the transport of monovalent ions within the ion exchange membrane while preventing the passage of divalent ions, thus improving the monovalent / divalent cation permeation selectivity of the ion exchange membrane.
[0037] (3) The cation exchange membrane for the separation of monovalent / divalent ions described in this invention introduces crown ether molecules on the polymer backbone, which is beneficial for the specific recognition of metal cations. This allows the prepared ion exchange membrane to provide new ion channels for specific metal cations. The size of the ion channels can be controlled by adjusting the length of the carbon chain on the crown ether molecules, thereby promoting the migration of specific ions under the action of electric field. Detailed Implementation
[0038] To further illustrate the technical solution of the present invention, the preferred embodiments of the present invention are described below in conjunction with specific examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the claims of the present invention.
[0039] Example 1:
[0040] (1) Synthesis of crown ether small molecules:
[0041] Weigh 12.0 g (108 mmol) catechol, 5.22 g (216 mmol) LiOH, 5.52 mL (54 mmol) 1,3-dibromopropane and 40 mL acetonitrile into a reaction vessel, heat to 100 °C under N2 atmosphere and react for 20 h; after the reaction, cool to room temperature, adjust pH to about 4, and rotary evaporate to obtain powdered intermediate 1.
[0042] Weigh 2.16 g (90 mmol) LiOH, 4.14 g (45 mmol) epichlorohydrin, and 11.70 g (45 mmol) intermediate 1 and dissolve them in deionized water. Under N2 atmosphere, heat to 50 °C and react for 10 h. After the reaction, cool to room temperature and filter to obtain powdered intermediate 2.
[0043] 8.85 g (72 mmol) of 1-bromopropane, 1.74 g (72 mmol) of NaH, and 11.40 g (36 mmol) of intermediate 2 were weighed and dissolved in 120 mL of THF. The mixture was stirred at room temperature under a N2 atmosphere for 20 h. After the reaction, Li was obtained by rotary evaporation. + Imprint DB14C4-C3.
[0044] Weigh 10.74 g (30 mmol) of DB14C4-C3, 3.60 g (60 mmol) of glacial acetic acid and 100 mL of Eaton reagent into a reaction vessel, heat to 50 °C under N2 atmosphere, and react for 20 h. After the reaction, cool to room temperature, wash three times with CH2Cl2 and 5% NaOH aqueous solution, dry the organic phase with MgSO4, and rotary evaporate to obtain the intermediate product DABC-1-C3.
[0045] 11.75 g (75 mmol) of m-chlorobenzoic acid, 4.26 g (30 mmol) of Na2HPO4 and 6.65 g (25 mmol) of DABC-1-C3 were weighed and dissolved in CH2Cl2. The mixture was stirred at room temperature under N2 atmosphere for 48 h. After the reaction, the crude product was obtained by rotary evaporation. The crude product was dissolved in CH2Cl2 and extracted three times with 5% NaOH aqueous solution. The organic phase was dried with MgSO4 and rotary evaporated to obtain the intermediate product DABC-2-C3.
[0046] Weigh 9.50 g (20 mmol) of DABC-2-C3 and dissolve it in a mixed solution of 225 mL methanol and 180 mL CH2Cl2. Slowly add 25 mL of a 6% NaOH methanol solution and stir at room temperature under N2 atmosphere for 24 h. After the reaction, neutralize with HCl at pH 1, filter the solid and wash with methanol to obtain the product DHBC-OH-C3.
[0047] (2) Synthesis of polyarylether sulfones containing amino and crown ether structures:
[0048] Weigh 6.25 g (16 mmol) of DHBC-OH-C3, 5.08 g (20 mmol) of 4,4'-difluorodiphenyl sulfone monomer, and 2.20 g (4 mmol) of 2,2'-bis(3-amino-4-hydroxyphenyl)hexafluoropropane monomer into a 250 mL round-bottom flask equipped with a water separator. Add 80 mL of NMP, along with 5.6 g of K2CO3 as a salt-forming agent and 45 mL of toluene as a dehydrating agent. Under nitrogen protection, react at 155 °C for 4 h, then raise the temperature to 165 °C and react for 3 h. After the solution cools to room temperature, pour it into 300 mL of ethanol and stir at high speed to flocculate and obtain a precipitate. After filtration, a brown solid is obtained, which is repeatedly washed with ethanol and water, and then dried under vacuum at 80 °C for 24 h to obtain 10.6 g of polyarylene ether sulfone with an amino group and crown ether structure in the main chain, with a molecular weight of 56,000. Its chemical structure is shown in formula (VII).
[0049] (3) Preparation of functionalized polyarylether sulfone:
[0050] A certain amount of 3.91 g (18 mmol) of 4-bromobutanesulfonic acid and 10 g of polyarylene ether sulfone were weighed and dissolved in DMF respectively. Under nitrogen protection, the former was added dropwise to the latter. The mixture was stirred at 40 °C for 24 h. After cooling to room temperature, the mixture was precipitated in isopropanol and washed and dried under vacuum at 80 °C for 12 h to obtain functionalized polyarylene ether sulfone, the chemical structure of which is shown in formula (VIII).
[0051] (4) Preparation of functionalized polyarylether sulfone cation exchange membranes:
[0052] 2.8g of the above-mentioned functionalized polyarylether sulfone polymer was dissolved in 60mL of NMP and stirred at 60℃ until completely dissolved to obtain a casting solution with a mass-volume concentration of 5%. The solution was allowed to stand to remove bubbles, and the degassed casting solution was coated onto a clean glass plate and vacuum dried for 24h to obtain a functionalized polyarylether sulfone cation exchange membrane.
[0053] (5) Performance of functionalized polyarylether sulfone cation exchange membranes:
[0054] The thickness, ion exchange capacity, tensile strength, and swelling ratio of the prepared cation exchange membrane for monovalent / divalent ion separation were experimentally tested using national standard methods. The sheet resistance, transport number, permeation selectivity, and ion flux of the ion exchange membrane were tested using a self-made 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).
[0055] Example 2:
[0056] (1) Synthesis of crown ether small molecules: The same preparation process as in Example 1 was used.
[0057] (2) Synthesis of polyarylether sulfone containing amino and crown ether structures: The same preparation process as in Example 1 was used.
[0058] (3) Preparation of functionalized polyarylene ether sulfone: The same preparation process as in Example 1 was used to prepare functionalized polyarylene ether sulfone, except that 3.44 g (19 mmol) of 5-bromopentanoic acid was added.
[0059] (4) Preparation of functionalized polyarylether sulfone cation exchange membrane: The same preparation process as in Example 1 was used.
[0060] (5) Performance of functionalized polyarylether sulfone cation exchange membranes:
[0061] The thickness, ion exchange capacity, tensile strength, and swelling ratio of the prepared cation exchange membrane for monovalent / divalent ion separation were experimentally tested using national standard methods. The sheet resistance, transport number, permeation selectivity, and ion flux of the ion exchange membrane were tested using a self-made 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] Example 3:
[0063] (1) Synthesis of crown ether small molecules: The same preparation process as in Example 1 was used.
[0064] (2) Synthesis of polyarylether sulfone containing amino and crown ether structures: The same preparation process as in Example 1 was used.
[0065] (3) Preparation of functionalized polyarylene ether sulfone: The same preparation process as in Example 1 was used to prepare functionalized polyarylene ether sulfone, except that 4.12 g (19 mmol) of 4-bromobutylphosphonic acid was added.
[0066] (4) Preparation of functionalized polyarylether sulfone cation exchange membrane: The same preparation process as in Example 1 was used.
[0067] (5) Performance of functionalized polyarylether sulfone cation exchange membranes:
[0068] The thickness, ion exchange capacity, tensile strength, and swelling ratio of the prepared cation exchange membrane for monovalent / divalent ion separation were experimentally tested using national standard methods. The sheet resistance, transport number, permeation selectivity, and ion flux of the ion exchange membrane were tested using a self-made 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).
[0069] Example 4:
[0070] (1) Synthesis of crown ether small molecules:
[0071] Intermediate 1 and intermediate 2 were prepared using the same preparation process as in Example 1.
[0072] Li was prepared using the same preparation process as in Example 1. + The only difference between the imprinted DB14C4-C5 and the one containing 10.88g (72mmol) of 1-bromopentane is that it contains 10.88g (72mmol) of 1-bromopentane.
[0073] DABC-1-C5 was prepared using the same preparation process as in Example 1, except that 11.58 g (30 mmol) of DB14C4-C5 was added.
[0074] DABC-2-C5 was prepared using the same preparation process as in Example 1, except that 7.07 g (25 mmol) of DABC-1-C5 was added.
[0075] DABC-OH-C5 was prepared using the same preparation process as in Example 1, except that 10.06 g (20 mmol) of DABC-2-C5 was added.
[0076] (2) Synthesis of polyarylether sulfone containing amino and crown ether structures: It was prepared using the same preparation process as in Example 1, except that 6.70 g (16 mmol) of DHBC-OH-C5 was added.
[0077] (3) Preparation of functionalized polyarylether sulfone:
[0078] Functionalized polyarylene sulfones were prepared using the same preparation process as in Example 1, except that 3.91 g (18 mmol) of 4-bromobutanesulfonic acid was added.
[0079] (4) Preparation of functionalized polyarylether sulfone cation exchange membrane: The same preparation process as in Example 1 was used.
[0080] (5) Performance of functionalized polyarylether sulfone cation exchange membranes:
[0081] The thickness, ion exchange capacity, tensile strength, and swelling ratio of the prepared cation exchange membrane for monovalent / divalent ion separation were experimentally tested using national standard methods. The sheet resistance, transport number, permeation selectivity, and ion flux of the ion exchange membrane were tested using a self-made 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] Example 5:
[0083] (1) Synthesis of crown ether small molecules: The same preparation process as in Example 4 was used.
[0084] (2) Synthesis of polyarylether sulfone containing amino and crown ether structures: The same preparation process as in Example 4 was used.
[0085] (3) Preparation of functionalized polyarylether sulfone:
[0086] Functionalized polyarylene sulfones were prepared using the same preparation process as in Example 4, except that 3.26 g (18 mmol) of 5-bromopentanoic acid was added.
[0087] (4) Preparation of functionalized polyarylether sulfone cation exchange membrane: The same preparation process as in Example 1 was used.
[0088] (5) Performance of functionalized polyarylether sulfone cation exchange membranes:
[0089] The thickness, ion exchange capacity, tensile strength, and swelling ratio of the prepared cation exchange membrane for monovalent / divalent ion separation were experimentally tested using national standard methods. The sheet resistance, transport number, permeation selectivity, and ion flux of the ion exchange membrane were tested using a self-made 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).
[0090] Example 6:
[0091] (1) Synthesis of crown ether small molecules: The same preparation process as in Example 4 was used.
[0092] (2) Synthesis of polyarylether sulfone containing amino and crown ether structures: The same preparation process as in Example 4 was used.
[0093] (3) Preparation of functionalized polyarylether sulfone:
[0094] Functionalized polyarylene sulfones were prepared using the same preparation process as in Example 4, except that 3.91 g (18 mmol) of 4-bromobutylphosphonic acid was added.
[0095] (4) Preparation of functionalized polyarylether sulfone cation exchange membrane: The same preparation process as in Example 1 was used.
[0096] (5) Performance of functionalized polyarylether sulfone cation exchange membranes:
[0097] The thickness, ion exchange capacity, tensile strength, and swelling ratio of the prepared cation exchange membrane for monovalent / divalent ion separation were experimentally tested using national standard methods. The sheet resistance, transport number, permeation selectivity, and ion flux of the ion exchange membrane were tested using a self-made 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).
[0098] Example 7:
[0099] (1) Synthesis of crown ether small molecules:
[0100] Intermediate 1 and intermediate 2 were prepared using the same preparation process as in Example 1.
[0101] Li was prepared using the same preparation process as in Example 1. + The only difference between the imprinted DB14C4-C7 and the one containing 12.88g (72mmol) of 1-bromoheptane is that it contains 12.88g (72mmol) of 1-bromoheptane.
[0102] DABC-1-C7 was prepared using the same preparation process as in Example 1, except that 12.45 g (30 mmol) of DB14C4-C7 was added.
[0103] DABC-2-C7 was prepared using the same preparation process as in Example 1, except that 7.49 g (25 mmol) of DABC-1-C7 was added.
[0104] DABC-OH-C7 was prepared using the same preparation process as in Example 1, except that 10.62 g (20 mmol) of DABC-2-C7 was added.
[0105] (2) Synthesis of polyarylether sulfone containing amino and crown ether structures: It was prepared using the same preparation process as in Example 1, except that 7.14 g (16 mmol) DHBC-OH-C7 was added.
[0106] (3) Preparation of functionalized polyarylether sulfone:
[0107] Functionalized polyarylene sulfones were prepared using the same preparation process as in Example 1, except that 3.69 g (17 mmol) of 4-bromobutanesulfonic acid was added.
[0108] (4) Preparation of functionalized polyarylether sulfone cation exchange membrane: The same preparation process as in Example 1 was used.
[0109] (5) Performance of functionalized polyarylether sulfone cation exchange membranes:
[0110] The thickness, ion exchange capacity, tensile strength, and swelling ratio of the prepared cation exchange membrane for monovalent / divalent ion separation were experimentally tested using national standard methods. The sheet resistance, transport number, permeation selectivity, and ion flux of the ion exchange membrane were tested using a self-made 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).
[0111] Example 8:
[0112] (1) Synthesis of crown ether small molecules: The same preparation process as in Example 7 was used.
[0113] (2) Synthesis of polyarylether sulfone containing amino and crown ether structures: The same preparation process as in Example 7 was used.
[0114] (3) Preparation of functionalized polyarylether sulfone:
[0115] Functionalized polyarylene sulfones were prepared using the same preparation process as in Example 7, except that 3.26 g (18 mmol) of 5-bromopentanoic acid was added.
[0116] (4) Preparation of functionalized polyarylether sulfone cation exchange membrane: The same preparation process as in Example 1 was used.
[0117] (5) Performance of functionalized polyarylether sulfone cation exchange membranes:
[0118] The thickness, ion exchange capacity, tensile strength, and swelling ratio of the prepared cation exchange membrane for monovalent / divalent ion separation were experimentally tested using national standard methods. The sheet resistance, transport number, permeation selectivity, and ion flux of the ion exchange membrane were tested using a self-made 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).
[0119] Example 9:
[0120] (1) Synthesis of crown ether small molecules: The same preparation process as in Example 7 was used.
[0121] (2) Synthesis of polyarylether sulfone containing amino and crown ether structures: The same preparation process as in Example 7 was used.
[0122] (3) Preparation of functionalized polyarylether sulfone:
[0123] Functionalized polyarylene sulfones were prepared using the same preparation process as in Example 7, except that 3.91 g (18 mmol) of 4-bromobutylphosphonic acid was added.
[0124] (4) Preparation of functionalized polyarylether sulfone cation exchange membrane: The same preparation process as in Example 1 was used.
[0125] (5) Performance of functionalized polyarylether sulfone cation exchange membranes:
[0126] The thickness, ion exchange capacity, tensile strength, and swelling ratio of the prepared cation exchange membrane for monovalent / divalent ion separation were experimentally tested using national standard methods. The sheet resistance, transport number, permeation selectivity, and ion flux of the ion exchange membrane were tested using a self-made 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).
[0127]
[0128] Table 1.
Claims
1. A method for preparing a monovalent / divalent cation separation ion exchange membrane, comprising the following steps: (1) Weigh a certain amount of catechol, LiOH, 1,3-dibromopropane and acetonitrile, heat to reflux under N2 atmosphere; after reaction, cool to room temperature, adjust pH to weak acid, rotary evaporation to obtain a powdery first intermediate as shown in formula (I); (2) Weigh a certain amount of epichlorohydrin, LiOH, and the first intermediate prepared in step (1) are dissolved in deionized water, heated and kept for several hours under N2 atmosphere; after reaction, cool to room temperature, filter to obtain a powdery second intermediate as shown in formula (II); (3) Weigh a certain amount of 1-bromopropane / 1-bromopentane / 1-bromohexane, NaH, and the second intermediate prepared in step (2) into a polar solvent, stir at room temperature under N2atmosphere for 20 h; after the reaction, rotary evaporation to obtain Li as shown in formula (III) + DB14C4-C3 / DB14C4-C5 / DB14C4-C7; (4) Weigh a certain amount of DB14C4-C3 / DB14C4-C5 / DB14C4-C7 prepared in step (3), glacial acetic acid and Eaton reagent, heat and keep for several hours under N2 atmosphere; after reaction, cool to room temperature, wash with CH2Cl2 and 5% NaOH aqueous solution three times, dry the organic phase with MgSO4, rotary evaporation to obtain an intermediate product DABC-1-C3 / DABC-1-C5 / DABC-1-C7 as shown in formula (IV); (5) Weigh a certain amount of m-chloroperbenzoic acid, Na2HPO4, and DABC-1-C3 / DABC-1-C5 / DABC-1-C7 prepared in step (4) are dissolved in CH2Cl2, stirred for several hours at room temperature under N2 atmosphere; after reaction, rotary evaporation to obtain a crude product; dissolve the crude product in CH2Cl2 and extract with NaOH aqueous solution three times, dry the organic phase with MgSO4, rotary evaporation to obtain an intermediate product DABC-2-C3 / DABC-2-C5 / DABC-2-C7 as shown in formula (V); (6) Weigh a certain amount of DABC-2-C3 / DABC-2-C5 / DABC-2-C7 prepared in step (5) is dissolved in a mixed solution of methanol and CH2Cl2, slowly drop 6% NaOH methanol solution by mass fraction, stirred for several hours at room temperature under N2 atmosphere; after reaction, neutralize with HCl solution to obtain a solid crude product, filter the solid and wash with methanol, vacuum drying to obtain a product DHBC-OH-C3 / DHBC-OH-C5 / DHBC-OH-C7 as shown in formula (VI); (7) Weigh a certain amount of DHBC-OH-C3 / DHBC-OH-C5 / DHBC-OH-C7, 4,4'-difluorodiphenyl sulfone monomer and 2,2'-bis(3-amino 4-hydroxyphenyl) hexafluoropropane, dissolve in a high-boiling polar aprotic solvent, use potassium carbonate as a salting agent, toluene as a water-carrying agent, and carry out polycondensation reaction at 100-180°C under nitrogen protection for 3-24 hours. After the reaction is completed, separate and dry to obtain a polyarylether sulfone copolymer containing amino groups and crown ether structures in the main chain, with a molecular weight of 30,000-60,000. In formula (VII), x and y represent the mole percentages of two chain links, x% and y%, respectively, and x+y=100; wherein x=1-100, y=1-100; wherein 2,2'-bis(3-amino 4-hydroxyphenyl) hexafluoropropane, DHBC-OH-C3 / DHBC-OH-C5 / DHBC-OH-C7, the molar ratio of the feed is 0-40%: 100-60%, and the chemical structure is shown in formula (VII); (8) Weigh a certain amount of 4-bromobutane sulfonic acid / 5-bromopentanoic acid / 4-bromobutyl phosphonic acid and the polyarylether sulfone copolymer obtained in step (7) respectively, dissolve in DMF respectively, then drop the former into the latter under nitrogen protection, stir at 20-90°C for 3-24 hours, after being cooled to room temperature, filter, precipitate the filtrate with ethyl acetate or diethyl ether or isopropyl alcohol, and wash and dry under vacuum to obtain a functionalized polyarylether sulfone, and the chemical structure is shown in formula (VIII); (9) Dissolve the functionalized polyarylether sulfone in an organic solvent, stand to remove bubbles to obtain a casting solution, the mass / volume concentration of the functionalized polyarylether sulfone in the casting solution is 3-8%, coat the casting solution on a clean glass plate, and dry under vacuum at 40-150°C for 3-24 hours to obtain a functionalized polyarylether sulfone cation exchange membrane.
2. The method for preparing a monovalent / divalent cation separation ion exchange membrane according to claim 1, characterized by: The reaction temperature in step (1) is 80-120°C, and the reaction time is 10-24h.
3. The method for preparing a monovalent / divalent cation separation ion exchange membrane according to claim 1, characterized by: The reaction temperature in step (2) is 30-80°C, and the reaction time is 10-24h.
4. The method for preparing a monovalent / divalent cation separation ion exchange membrane according to claim 1, characterized by: The polar solvent in step (3) is one or more of tetrahydrofuran, N-methyl pyrrolidone and N,N dimethylformamide.
5. The method for preparing a monovalent / divalent cation separation ion exchange membrane according to claim 1, characterized by: The reaction temperature in step (4) is 30-80°C, and the reaction time is 10-24h.
6. The method for preparing a monovalent / divalent cation separation ion exchange membrane according to claim 1, characterized by: The mass / volume concentration of the NaOH aqueous solution in step (5) is 3-8%.
7. The method for preparing a monovalent / divalent cation separation ion exchange membrane according to claim 1, characterized by: The reaction time in step (6) is 10-24h, and the pH of the HCl solution is 0-4.
8. The method for preparing a monovalent / divalent cation separation ion exchange membrane according to claim 1, characterized by: The molar ratio of 2,2'-bis(3-amino 4-hydroxyphenyl) hexafluoropropane to DHBC-OH-C3 / DHBC-OH-C5 / DHBC-OH-C7 in step (7) is 20%:80%; the high-boiling polar aprotic solvent is N-methyl pyrrolidone, and the polycondensation reaction conditions are 155°C for 4 hours, then raised to 165°C for 3 hours.
9. The method for preparing a monovalent / divalent cation separation ion exchange membrane according to claim 1, characterized by: The vacuum drying temperature in step (8) is 60-120°C.
10. The method for preparing a monovalent / divalent cation separation ion exchange membrane according to claim 1, characterized by: The mass / volume concentration of the polyarylether sulfone in the casting solution in step (9) is 5%.