A preparation method of an acid and alkali resistant anion exchange membrane with high anion flux

Abstract

The application belongs to the technical field of membranes, and relates to a preparation method of an acid and alkali resistant anion exchange membrane with high anion flux, comprising the following steps: dissolving polysulfone in an organic solvent, adding polyformaldehyde and trimethylchlorosilane, fully mixing and sealing and stirring for 1-120 min, then adding tin chloride drop by drop, fully mixing and sealing and stirring, reacting for 1-10 d at 10-50 DEG C, pouring into an alcohol solvent, and obtaining chlorinated polysulfone material; dissolving the chlorinated polysulfone material in N,N-dimethylformamide, adding 1,4-diazido bicyclo[2,2,2]octane, fully mixing and sealing and stirring, reacting, ultrasonic defoaming, obtaining a casting solution, scraping into a film, vacuum drying, and obtaining the anion exchange membrane. The preparation process is simple and easy to operate, and the prepared anion exchange membrane has good acid and alkali resistance, high ion flux and impact mechanical properties.

Description

Technical Field

[0001] This invention belongs to the field of membrane technology, and relates to ion exchange membranes, and more particularly to a method for preparing an anion exchange membrane that is both acid and alkali resistant and has a high anion flux. Technical Background

[0002] With the rapid development of industrialization, industrial wastewater contains a large number of ions. To address this type of wastewater problem, the development of technologies for the effective separation of ions from industrial wastewater has become a major focus for sustainable industrial development. Among these, the development of advanced composite membrane technology for ion separation has become a primary concern. Ion exchange membranes, as the core component of electrodialysis, have received significant attention due to their unique advantages in overcoming ion concentration polarization, particularly in removing or concentrating ions from high-concentration brine.

[0003] In electrodialysis, anion exchange membranes, cation exchange membranes, and bipolar membranes are widely used for ion removal, concentration, and recovery. However, traditional ion exchange membranes cannot meet the ever-evolving industrial demands due to the complex composition and pH of industrial wastewater. Furthermore, the lower ion flux requires higher energy consumption, thus limiting the application of related technologies.

[0004] Therefore, seeking and designing suitable materials for preparing ion exchange membranes with acid and alkali resistance and high ion flux has become an urgent development requirement.

[0005] Polysulfone is a polymer material with good toughness and high temperature resistance, exhibiting excellent performance in resisting acids and alkaline electrolytes, as well as high impact mechanical properties. In recent years, there has been research on membrane separation materials prepared using polysulfone as a matrix and their application in seawater desalination. Therefore, the application of polysulfone in the preparation of ion exchange membranes can be considered. Summary of the Invention

[0006] In view of the shortcomings of the prior art, the present invention aims to provide a method for preparing anion exchange membranes that are both acid and alkali resistant and have high anion flux.

[0007] A method for preparing an anion exchange membrane that combines acid and alkali resistance with high anion flux includes the following steps:

[0008] (1) Dissolve polysulfone in an organic solvent at a mass ratio of 1-50%, add 10-200% paraformaldehyde and 10-500% trimethylchlorosilane (based on the mass of the polysulfone material), mix thoroughly, seal and stir for 1-120 minutes, then add dropwise 0.1-50% of the mass of the polysulfone material.

[0009] 50% tin chloride was thoroughly mixed and stirred in a sealed container. After reacting at 10–50°C for 1–10 days, the mixture was poured into an alcohol solvent to obtain chlorinated polysulfone material.

[0010] The reaction equation is:

[0011]

[0012] (2) Dissolve chlorinated polysulfone material and N,N-dimethylformamide in a mass ratio of 1-50%, add 1,4-diazidobiscyclo[2,2,2]octane at a mass of 1-200% of the chlorinated polysulfone material, mix thoroughly and stir in a sealed container, react at 10-90℃ for 5-48h, then degas with ultrasound for 0.5-3h to obtain a casting solution, scrape it onto a horizontally placed dry glass plate to form a film, and vacuum dry it to obtain the final product;

[0013] The reaction equation is:

[0014]

[0015] In a preferred embodiment of the present invention, the organic solvent in step (1) is chloroform or dichloroform, preferably chloroform.

[0016] In a preferred embodiment of the present invention, the alcohol solvent in step (1) is anhydrous methanol or anhydrous ethanol, preferably anhydrous ethanol.

[0017] In the preferred embodiment of the present invention, the conditions for forming the film in step (2) are: ambient temperature of 15-60°C, humidity of 2-20%, and film thickness of 40-400 μm.

[0018] In the preferred embodiment of the present invention, the vacuum drying conditions in step (2) are: vacuum degree of 0 to 100 Pa and temperature of 50 to 85 °C.

[0019] The ion exchange capacity, water content, ductility, and membrane surface resistivity of the prepared anion exchange membrane were tested. Its morphology was characterized by scanning electron microscopy, and its molecular structure and chemical composition were analyzed by infrared spectroscopy.

[0020] Different types of anion exchange membranes were selected and assembled with commercial cation exchange membranes (Fujifilm CEM Type-I cation exchange membrane from Japan) into an electrodialysis device. Through the electrodialysis process, combined with the experimental data, the removal rate and concentration rate of the prepared anion exchange membranes for different salts were calculated.

[0021] Different types of anion exchange membranes were selected and immersed in solutions with different pH values. The initial pH values ​​of the solutions were set to 1, 3, 5, 7, 9, 11 and 13. After immersion for 48 hours, the anion exchange capacity was measured.

[0022] Beneficial effects

[0023] The preparation process of this invention is simple and easy to operate. The prepared anion exchange membrane has good acid and alkali resistance and high anion exchange capacity, up to 2.99 mmol / g. Attached Figure Description

[0024] Figure 1 Chemical structural formulas of the polysulfones involved in the reaction, the synthesized chlorinated polysulfones, and the quaternized polysulfones;

[0025] Figure 2 The anion exchange capacities of the five types of anion exchange membranes prepared;

[0026] Figure 3 The water content of the five types of anion exchange membranes prepared;

[0027] Figure 4 The stretchability of the five types of anion exchange membranes prepared;

[0028] Figure 5 The surface resistance of the five types of anion exchange membranes prepared;

[0029] Figure 6 Cross-sectional scanning electron microscope images of the five types of anion exchange membranes prepared;

[0030] Figure 7 Infrared characterization images of the five types of anion exchange membranes prepared;

[0031] Figure 8 Schematic diagram of electrodialysis membrane performance test;

[0032] Figure 9 The sodium chloride desalination efficiency of the four types of anion exchange membranes prepared;

[0033] Figure 10 The sodium chloride concentration efficiency of the four types of anion exchange membranes prepared;

[0034] Figure 11 The sodium nitrate desalination efficiency of the four types of anion exchange membranes prepared;

[0035] Figure 12 Sodium nitrate concentration efficiency of the four types of anion exchange membranes prepared;

[0036] Figure 13 The sodium sulfate desalination efficiency of the four types of anion exchange membranes prepared;

[0037] Figure 14 The sodium sulfate concentration efficiency of the four types of anion exchange membranes prepared;

[0038] Figure 15The sodium phosphate desalination efficiency of the four types of anion exchange membranes prepared;

[0039] Figure 16 The sodium phosphate concentration efficiency of the four types of anion exchange membranes prepared;

[0040] Figure 17 pH stability tests of the four types of anion exchange membranes prepared. Detailed Implementation

[0041] The present invention will be described in detail below with reference to embodiments, so that those skilled in the art can better understand the present invention, but the present invention is not limited to the following embodiments.

[0042] Unless otherwise specified, the terms used herein (including technical terms) shall be interpreted as having the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. It will also be understood that the terms used herein shall be interpreted as having the same meaning as they have in the context of this specification and related art, and shall not be interpreted in an idealized or excessive manner, unless specifically defined herein.

[0043] Comparison Example

[0044] Weigh out 5.0g of polysulfone (e.g.) Figure 1 A mixture of polysulfone (its chemical structure) and 250.0 g of trichloromethane solvent was added to a 500 mL three-necked flask. A clean magnetic stir bar was placed inside, and the flask was then placed in an oil bath at 30°C. The magnetic stirrer was turned on at 800 rpm until the polysulfone was completely dissolved. Then, 3.5 g of paraformaldehyde and 12.5 g of trimethylchlorosilane were weighed into the above mixture and thoroughly mixed. After 10 min, 0.5 g of tin chloride was added dropwise, and the reaction temperature was adjusted to 50°C. After reacting for 48 h, anhydrous ethanol was added and the mixture was dried to obtain chlorinated polysulfone. The chlorinated polysulfone was then rinsed three times with anhydrous ethanol to obtain pure chlorinated polysulfone (e.g., chlorinated polysulfone). Figure 1 b is its chemical structure). After drying, 1.0 g of polysulfone chloride and 0 g of 1,4-diazidobiscyclo[2,2,2]octane were weighed and dissolved in 5 mL of dimethyl sulfoxide. The reaction temperature was controlled at 30℃, and the mixture was magnetically stirred at 800 rpm. After 10 h, ultrasonic degassing was performed using an ultrasonic cleaner. After 2 h, a dried glass plate was placed in a horizontal constant temperature and humidity control chamber. The temperature of the control chamber was adjusted to 30℃, the humidity to 5%, and the thickness of the film scraper to 250 μm. The film was scraped on the dried glass plate. The obtained film was placed flat in a forced-air drying oven at 60℃. After 6 h, the film was taken out, thus obtaining a dried quaternized polysulfone film (e.g. Figure 1 c represents its chemical structure, and the membrane was named AEM#Q-0.

[0045] like Figure 2 'a' represents the ion exchange capacity of the prepared AEM#Q-0 anion exchange membrane; for example... Figure 3 'a' represents the water content of the prepared AEM#Q-0 anion exchange membrane; for example... Figure 4 'a' represents the ductility of the prepared AEM#Q-0 anion exchange membrane; such as Figure 5 'a' represents the surface resistivity of the prepared AEM#Q-0 anion exchange membrane; for example... Figure 6 , a is a scanning electron microscope image of the surface of the prepared AEM#Q-0 anion exchange membrane; as shown Figure 7 , a represents the infrared characterization of the prepared AEM#Q-0 anion exchange membrane.

[0046] Example 1

[0047] Following the same steps as the control example, simply replace 0g of 1,4-diazidobicyclo[2,2,2]octane with 0.1g of 1,4-diazidobicyclo[2,2,2]octane and name it AEM#Q-0.1. For example... Figure 2 b represents the ion exchange capacity of the prepared AEM#Q-0.1 anion exchange membrane; for example... Figure 3 b represents the water content of the prepared AEM#Q-0.1 anion exchange membrane; Figure 4 b represents the ductility of the prepared AEM#Q-0.1 anion exchange membrane; such as Figure 5 b represents the surface resistivity of the prepared AEM#Q-0.1 anion exchange membrane; for example... Figure 6 b is a scanning electron microscope image of the surface of the prepared AEM#Q-0.1 anion exchange membrane; as shown in Figure 1. Figure 7 b represents the infrared characterization of the prepared AEM#Q-0.1 anion exchange membrane.

[0048] Example 2

[0049] Following the same steps as the control example, simply replace 0g of 1,4-diazidobicyclo[2,2,2]octane with 0.5g of 1,4-diazidobicyclo[2,2,2]octane and name it AEM#Q-0.5. For example... Figure 2 c represents the ion exchange capacity of the prepared AEM#Q-0.5 anion exchange membrane; for example... Figure 3 c represents the water content of the prepared AEM#Q-0.5 anion exchange membrane; Figure 4 c represents the ductility of the prepared AEM#Q-0.5 anion exchange membrane; such as Figure 5 c represents the surface resistivity of the prepared AEM#Q-0.5 anion exchange membrane; for example... Figure 6 c is a scanning electron microscope image of the surface of the prepared AEM#Q-0.5 anion exchange membrane; as shown. Figure 7c represents the infrared characterization of the prepared AEM#Q-0.5 anion exchange membrane.

[0050] Example 3

[0051] Following the same steps as the control example, simply replace 0g of 1,4-diazidobicyclo[2,2,2]octane with 0.8g of 1,4-diazidobicyclo[2,2,2]octane and name it AEM#Q-0.8. For example... Figure 2 d represents the ion exchange capacity of the prepared AEM#Q-0.8 anion exchange membrane; for example... Figure 3 d represents the water content of the prepared AEM#Q-0.8 anion exchange membrane; for example... Figure 4 d represents the ductility of the prepared AEM#Q-0.8 anion exchange membrane; such as Figure 5 d represents the surface resistivity of the prepared AEM#Q-0.8 anion exchange membrane; for example... Figure 6 d is a scanning electron microscope image of the surface of the prepared AEM#Q-0.8 anion exchange membrane; as shown. Figure 7 d represents the infrared characterization of the prepared AEM#Q-0.8 anion exchange membrane.

[0052] Example 4

[0053] Following the same steps as the control example, simply replace 0g of 1,4-diazidobicyclo[2,2,2]octane with 1.2g of 1,4-diazidobicyclo[2,2,2]octane and name it AEM#Q-1.2. For example... Figure 2 e represents the ion exchange capacity of the prepared AEM#Q-1.2 anion exchange membrane; for example... Figure 3 e represents the water content of the prepared AEM#Q-1.2 anion exchange membrane; for example... Figure 4 e represents the ductility of the prepared AEM#Q-1.2 anion exchange membrane; such as Figure 5 e represents the surface resistivity of the prepared AEM#Q-1.2 anion exchange membrane; for example... Figure 6 e is a scanning electron microscope image of the surface of the prepared AEM#Q-1.2 anion exchange membrane; as shown. Figure 7 , e represents the infrared characterization of the prepared AEM#Q-1.2 anion exchange membrane.

[0054] Experimental Example 1

[0055] like Figure 8The diagram shows a schematic of the electrodialysis process. AEM#Q-0.1, AEM#Q-0.5, AEM#Q-0.8, and AEM#Q-1.2 anion exchange membranes were selected and assembled into the electrodialysis equipment along with a commercially available cation exchange membrane (Fujifilm CEM Type-I cation exchange membrane from Japan). The initial feed solution was set as follows: 100 mL of 10.0 g / L sodium chloride solution (desalination chamber) and 100 mL of 10.0 g / L sodium chloride solution. -1 Sodium chloride solution (concentration chamber). Electrode solution: 400 mL, 10.0 g·L⁻¹ -1 Sodium sulfate solution circulation (15.0V regulated, membrane area 20cm²) 2 The concentration in the dilute compartment (ct) and the concentration in the concentrated compartment (c't) were measured every 10 minutes to calculate the sodium chloride removal rate and concentration rate of the prepared anion exchange membrane, as shown below. Figure 9 and Figure 10 As shown in the figure, the AEM#Q-0.8 anion exchange membrane has the highest removal and concentration rates of sodium chloride.

[0056] The formula for calculating desalination efficiency is:

[0057]

[0058] The formula for calculating concentration efficiency is:

[0059]

[0060] Experiment Example 2

[0061] Anion exchange membranes of AEM#Q-0.1, AEM#Q-0.5, AEM#Q-0.8, and AEM#Q-1.2 were selected and assembled with commercially available cation exchange membranes (Fujifilm CEM Type-I cation exchange membrane from Japan) into an electrodialysis apparatus. The initial feed solution was set as follows: 100 mL of 10.0 g / L sodium nitrate solution (desalination chamber) and 100 mL of 10.0 g / L sodium nitrate solution. -1 Sodium nitrate solution (concentration chamber). Electrode solution: 400 mL, 10.0 g·L⁻¹ -1 Sodium sulfate solution circulation (15.0V regulated, membrane area 20cm²) 2 The concentration in the dilute compartment (ct) and the concentration in the concentrated compartment (c't) were measured every 10 minutes to calculate the sodium nitrate removal rate and concentration rate of the prepared anion exchange membrane, as shown below. Figure 11 and Figure 12 As shown in the figure, the AEM#Q-0.8 anion exchange membrane has the highest removal and concentration rates of sodium nitrate.

[0062] Experimental Example 3

[0063] Anion exchange membranes of AEM#Q-0.1, AEM#Q-0.5, AEM#Q-0.8, and AEM#Q-1.2 were selected and assembled with commercially available cation exchange membranes (Fujifilm CEM Type-I cation exchange membrane from Japan) into an electrodialysis apparatus. The initial feed solution was set as follows: 100 mL of 10.0 g / L sodium sulfate solution (desalination chamber) and 100 mL of 10.0 g / L sodium sulfate solution. -1 Sodium sulfate solution (concentration chamber). Electrode solution: 400 mL, 10.0 g·L⁻¹ -1 Sodium sulfate solution circulation (15.0V regulated, membrane area 20cm²) 2 The concentration in the dilute compartment (ct) and the concentration in the concentrated compartment (c't) were measured every 10 minutes to calculate the sodium sulfate removal rate and concentration rate of the prepared anion exchange membrane, as shown below. Figure 13 and Figure 14 As shown in the figure, the AEM#Q-0.8 anion exchange membrane has the highest sodium sulfate removal rate, but the AEM#Q-0.5 anion exchange membrane has the highest sodium sulfate concentration rate.

[0064] Experiment Example 4

[0065] Anion exchange membranes of AEM#Q-0.1, AEM#Q-0.5, AEM#Q-0.8, and AEM#Q-1.2 were selected and assembled with commercially available cation exchange membranes (Fujifilm CEM Type-I cation exchange membrane from Japan) into an electrodialysis apparatus. The initial feed solution was set as follows: 100 mL of 10.0 g / L sodium phosphate solution (desalination chamber) and 100 mL of 10.0 g / L sodium phosphate solution. -1 Sodium phosphate solution (concentration chamber). Electrode solution: 400 mL, 10.0 g·L⁻¹ -1 Sodium sulfate solution circulation (15.0V regulated, membrane area 20cm²) 2 The concentration in the dilute compartment (ct) and the concentration in the concentrated compartment (c't) were measured every 10 minutes to calculate the sodium phosphate removal rate and concentration rate of the prepared anion exchange membrane, as shown below. Figure 15 and Figure 16 As shown in the figure, the AEM#Q-0.8 anion exchange membrane has the highest removal and concentration rates of sodium phosphate.

[0066] Experimental Example 5

[0067] Anion exchange membranes of AEM#Q-0.1, AEM#Q-0.5, AEM#Q-0.8, and AEM#Q-1.2 were selected and immersed in solutions with different pH values. The initial pH values ​​of the solutions were set to 1, 3, 5, 7, 9, 11, and 13. After immersion for 48 hours, their anion exchange capacities were measured. Figure 17As shown in the figure, the four anion exchange membranes have the highest exchange capacity at a solution pH of 7. In addition, the AEM#Q-0.8 anion exchange membrane has the highest exchange capacity in solutions with different pH values. However, the exchange capacity of the AEM#Q-0.5 anion exchange membrane does not change significantly with the change of solution pH.

[0068] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made using the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for preparing an anion exchange membrane that combines acid and alkali resistance with high anion flux, characterized in that, Includes the following steps: (1) Polysulfone is dissolved in an organic solvent at a mass ratio of 1-50%. Then, 10-200% of the mass of the polysulfone material (paraformaldehyde) and 10-500% of the mass of trimethylchlorosilane are added. The mixture is thoroughly mixed and stirred in a sealed container for 1-120 min. Next, 0.1-50% of the mass of the polysulfone material (tin chloride) is added dropwise. The mixture is thoroughly mixed and stirred in a sealed container. The mixture is reacted at 10-50°C for 1-10 days. Finally, it is poured into an alcohol solvent to obtain the chlorinated polysulfone material. The reaction equation is: ； (2) Dissolve chlorinated polysulfone material in N,N-dimethylformamide at a mass ratio of 1-50%, add 1,4-diazidobiscyclo[2,2,2]octane at a mass ratio of 10-120% of the chlorinated polysulfone material, mix thoroughly and stir under sealed conditions, react at 10-90℃ for 5-48 hours, then degas using ultrasound for 0.5-3 hours to obtain a casting solution, coat it into a film, and vacuum dry it to obtain the final product. The reaction equation is: 。 2. The method for preparing anion exchange membrane with both acid and alkali resistance and high anion flux according to claim 1, characterized in that: The organic solvent mentioned in step (1) is chloroform or dichloroform.

3. The method for preparing anion exchange membrane with both acid and alkali resistance and high anion flux according to claim 2, characterized in that: The organic solvent mentioned in step (1) is chloroform.

4. The method for preparing anion exchange membrane with both acid and alkali resistance and high anion flux according to claim 1, characterized in that: The alcohol solvent mentioned in step (1) is anhydrous methanol or anhydrous ethanol.

5. The method for preparing anion exchange membrane with both acid and alkali resistance and high anion flux according to claim 4, characterized in that: The alcohol solvent mentioned in step (1) is anhydrous ethanol.

6. The method for preparing anion exchange membrane with both acid and alkali resistance and high anion flux according to claim 1, characterized in that, The conditions for film preparation in step (2) are: ambient temperature of 15-60℃, humidity of 2-20%, and film thickness of 40-400μm.

7. The method for preparing anion exchange membrane with both acid and alkali resistance and high anion flux according to claim 1, characterized in that, The conditions for vacuum drying in step (2) are: vacuum degree of 0 to 100 Pa and temperature of 50 to 85℃.

8. The anion exchange membrane prepared by any one of claims 1-7.

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