A bipolar membrane for degrading harmful chemicals and a method for preparing the same

Abstract

The application provides a bipolar membrane for degrading harmful chemicals and a preparation method thereof, and the preparation method comprises the following steps: continuously casting a cation exchange membrane liquid on a glass plate, and heating and drying to obtain a cation exchange membrane; uniformly dispersing MOF in a polyethyleneimine aqueous solution to obtain an intermediate interface layer solution, spraying the intermediate interface layer solution on the surface of the cation exchange membrane, and heating and drying to obtain a cation exchange membrane with an intermediate interface layer; continuously casting an anion exchange membrane liquid on the intermediate interface layer, and heating and drying to obtain a bipolar membrane composed of the cation exchange membrane, the anion exchange membrane and the intermediate interface layer. The bipolar membrane can significantly improve the degradation capacity of the membrane material for harmful chemicals by introducing the MOF material, and thus the overall protection performance of the chemical protective clothing is improved.

Description

Technical Field

[0001] This invention belongs to the field of chemical protection technology, specifically relating to a bipolar membrane for degrading harmful chemicals and its preparation method. Background Technology

[0002] Chemical agents are extremely toxic; even trace exposure can cause serious casualties and environmental damage. Therefore, efficient decontamination of contaminated water, equipment, and the environment is crucial. However, while traditional decontamination methods can effectively degrade agents, they often result in severe secondary pollution, particularly the generation of highly alkaline and saline wastewater. This not only increases the difficulty of subsequent treatment but also causes long-term damage to the ecological environment and equipment. The limitations of the current mainstream three-in-one disinfectant system (composed of calcium hypochlorite, calcium hydroxide, and calcium chloride) are becoming increasingly apparent. This reaction system requires maintaining a strongly alkaline environment with a pH > 10 to ensure the oxidative activity of hypochlorite ions. A single treatment requires a large amount of sodium hydroxide, significantly increasing disposal costs and resulting in excessively high total dissolved solids content in the treated wastewater. More critically, the high salinity of the wastewater causes electrochemical corrosion to the metal components of the decontamination equipment, and the resulting soil compaction and salinization require several years for natural recovery. Therefore, a novel decontamination technology based on bipolar membrane electrochemistry is needed. This technology utilizes the efficient water dissociation properties of bipolar membranes under an electric field to provide an in-situ acid-base environment, enabling automatic pH adjustment of the system. This not only significantly reduces treatment costs but also avoids the problems of high-salt and alkaline wastewater and heavy metal residues. It achieves the unity of efficient degradation of toxic agents and near-zero wastewater discharge, providing an economical, efficient, and sustainable solution for the field of chemical protection, with significant military, ecological, and economic benefits. Summary of the Invention

[0003] (a) Technical problems to be solved This invention proposes a bipolar membrane for degrading harmful chemicals and its preparation method, in order to solve the technical problems of pollution and the need to improve the decontamination capacity of existing decontamination methods.

[0004] (II) Technical Solution To address the aforementioned technical problems, this invention proposes a method for preparing a bipolar membrane for degrading harmful chemical substances, the method comprising the following steps: S1. Sulfonic acid type polyvinylidene fluoride cation exchange membrane solution is cast onto a glass plate and heated to dry to obtain a cation exchange membrane; S2. A metal-organic framework (MOF) is uniformly dispersed in an aqueous solution of polyethyleneimine to obtain an intermediate interface layer solution. The intermediate interface layer solution is sprayed onto the surface of a cation exchange membrane and then heated and dried to obtain a cation exchange membrane with an intermediate interface layer. S3. The imidazole-type polyphenylene ether anion exchange membrane solution is extended onto the intermediate interface layer and heated and dried to obtain a bipolar membrane consisting of a cation exchange membrane, an anion exchange membrane, and an intermediate interface layer.

[0005] Furthermore, in steps S1 to S3, the material is heated and dried on a flat plate heater at a temperature of 50 to 90°C.

[0006] Furthermore, in step S1, the thickness of the cation exchange membrane is 20~100μm.

[0007] Furthermore, in step S3, the thickness of the anion exchange membrane is 20~100μm.

[0008] Furthermore, in step S2, MOF is one of MOF-808, UiO-66, and UiO-66-NH2.

[0009] Furthermore, in step S2, the amount of intermediate interface layer solution sprayed onto the surface of the cation exchange membrane is 0.05~0.8 mL.

[0010] Further, in step S1, the preparation method of the sulfonic acid type polyvinylidene fluoride cation exchange membrane solution is as follows: polyvinylidene fluoride (PVDF), sodium p-styrene sulfonate (SSS), and divinylbenzene (DVB) are added to N,N-dimethylformamide (DMF), stirred and dissolved, and then azobisisobutyronitrile (AIBN) initiator is added. The amount of AIBN is 1-5 wt% of the mass of SSS. The temperature is raised to 50-90°C, and a free radical polymerization reaction is carried out under a nitrogen atmosphere. The reaction is terminated after 6-14 hours to obtain the sulfonic acid type polyvinylidene fluoride cation exchange membrane solution PVDF-g-SSS.

[0011] Further, in step S2, the intermediate interface layer solution is prepared by: preparing a 1-10 wt% aqueous solution of polyethyleneimine, adding MOF and stirring for 6-24 h to disperse it evenly, wherein the content of MOF is 1-10 wt% of the content of polyethyleneimine, thereby obtaining the intermediate interface layer solution.

[0012] Further, in step S3, the preparation method of the imidazole-type polyphenylene ether anion exchange membrane solution is as follows: polyphenylene ether (PPO) is added to chlorobenzene, stirred and dissolved, then N-bromosuccinimide (NBS) and azobisisobutyronitrile (AIBN) are added, with the amount of AIBN added being 2-10 wt% of the mass of NBS. The temperature is raised to 100-160℃, and a free radical polymerization reaction is carried out under a nitrogen atmosphere. The reaction is terminated after 6-12 hours. The cooled reaction solution is poured into ethanol and filtered and dried to obtain a crude product. The crude product is redissolved in dichloromethane (DCM), poured into ethanol, filtered and dried to obtain brominated polyphenylene ether (BPPO), with a bromination degree of 20-50%. BPPO is dissolved in N-methylpyrrolidone (NMP), 1,2-dimethylimidazolium (DMI) is added, the temperature is raised to 60-90℃, and the reaction is terminated after 6-12 hours to obtain the imidazole-type polyphenylene ether anion exchange membrane solution PPO-DIM.

[0013] Furthermore, the present invention also proposes a bipolar membrane for degrading harmful chemicals, which is prepared by the above method.

[0014] (III) Beneficial Effects This invention proposes a bipolar membrane for degrading hazardous chemicals and its preparation method. The preparation method includes: casting a cation exchange membrane solution onto a glass plate and heating and drying it to obtain a cation exchange membrane; uniformly dispersing MOF in a polyethyleneimine aqueous solution to obtain an intermediate interface layer solution; spraying the intermediate interface layer solution onto the surface of the cation exchange membrane and heating and drying it to obtain a cation exchange membrane with an intermediate interface layer; casting an anion exchange membrane solution onto the intermediate interface layer and heating and drying it to obtain a bipolar membrane composed of a cation exchange membrane, an anion exchange membrane, and an intermediate interface layer. This bipolar membrane, by introducing MOF material, utilizes its large specific surface area, adjustable pore size distribution, and excellent catalytic performance to significantly enhance the membrane material's ability to degrade hazardous chemicals, thereby improving the overall protective performance of chemical protective clothing.

[0015] The beneficial effects of this invention specifically include: 1. The prepared bipolar membrane with added MOF interlayer has a low water dissociation voltage, which is reduced by 65.5% compared with the bipolar membrane without any catalyst.

[0016] 2. Introducing MOFs with high specific surface area and high porosity into the intermediate layer of bipolar films can enhance their catalytic degradation ability for DMNP.

[0017] 3. The bipolar membrane with added MOF interlayer can effectively degrade harmful chemicals while ensuring the passage of water vapor. It has good moisture permeability and excellent selective permeability, which meets the moisture permeability requirements of protective materials and can effectively block the penetration of chemical agents. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of the bipolar membrane prepared in Example 1; Figure 2a This is a scanning electron microscope image of the surface morphology of the cation exchange membrane in Example 1. Figure 2b This is a scanning electron microscope image of the surface morphology of the anion exchange membrane. Figure 3 A cross-sectional scanning electron microscope image of the bipolar film prepared in Example 1; Figure 4 The current-voltage curve of the bipolar film prepared in Example 1; Figure 5 The graph shows the degradation conversion efficiency of the bipolar membrane prepared in Example 1 for DMNP. Figure 6 The curve showing the change in pH value of the alkaline chamber solution over time during the degradation process of the bipolar membrane prepared in Example 1; Figure 7 The current-voltage curve of the bipolar film prepared in Example 2; Figure 8 The graph shows the degradation conversion rate of DMNP by the bipolar membrane prepared in Example 2. Detailed Implementation

[0019] To make the objectives, contents, and advantages of the present invention clearer, the specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples.

[0020] Example 1 The preparation method of the bipolar film in this embodiment includes the following steps: 1. Preparation of cation exchange membrane solution PVDF (5g), SSS (3.5g), and DVB (0.35mL) were stirred evenly in DMF. Then, AIBN (0.035g) was added under a nitrogen atmosphere, and the mixture was reacted at 80℃ for 10h to obtain the cation exchange membrane solution (PVDF-g-SSS). The membrane solution was uniformly coated onto a glass plate and dried at 80℃ for 8h to obtain the cation exchange membrane solution.

[0021] 2. Preparation of the intermediate interface layer solution Prepare a 4wt% aqueous solution of polyethyleneimine, add 0.5g of MOF-808, and stir until evenly dispersed to obtain an intermediate interface layer solution.

[0022] 3. Preparation of anion exchange membrane solution PPO (18g) was added to chlorobenzene and stirred until dissolved. Then, NBS (16g) and AIBN (1.4g) were added, and the mixture was heated to 140℃ under a nitrogen atmosphere for free radical polymerization. The reaction was terminated after 6 hours. The cooled reaction solution was poured into ethanol, filtered, and dried to obtain a crude product. The crude product was redissolved in DCM, poured into ethanol, filtered, and dried to obtain BPPO with a bromination degree of 40%. BPPO (6.4g) was dissolved in NMP, and DMI (4g) was added. The reaction was terminated after 8 hours at 80℃. 3% MOF-808 was added to the reaction solution (PPO-DIM) to obtain anion exchange membrane solution.

[0023] 4. Preparation of bipolar films A cation exchange membrane solution was cast onto a glass plate and dried at 70°C using a flat-plate heater to obtain a cation exchange membrane. 0.3 mL of an intermediate interface layer solution was uniformly sprayed onto the surface of the cation exchange membrane and dried at 70°C using a flat-plate heater. An anion exchange membrane solution was cast onto the surface of the intermediate layer and dried at 70°C using a flat-plate heater to obtain a bipolar membrane, the structure of which is shown below. Figure 1 As shown.

[0024] Figure 2a This is a SEM image of a cation exchange membrane. Figure 2b This is a SEM image of an anion exchange membrane. Figure 2a and 2b This clearly shows that both surfaces are dense and non-porous.

[0025] like Figure 3 As shown in the cross-sectional scanning electron microscope image of the bipolar membrane, the upper side is the anion exchange membrane layer and the lower side is the cation exchange membrane layer. There is a clear "boundary" between the two membrane layers, which corresponds to the middle interface layer of the bipolar membrane. The whole structure presents a "sandwich" structure. This obvious layering characteristic can effectively prevent the mutual penetration of the anion and cation exchange membrane layers and promote water dissociation.

[0026] The specific steps for testing the current-voltage curve of the bipolar membrane are as follows: The bipolar membrane to be tested was immersed in a 0.5 mol / L sodium chloride (NaCl) solution for 24 hours. Then, the bipolar membrane was placed in a current-voltage (IV) curve testing device, with the cation exchange membrane layer facing the negative electrode and the anion exchange membrane layer facing the positive electrode. Membranes were used on both sides to separate the electrode chamber and the acid-base chamber. The electrode chamber used a 0.5 mol / L sodium chloride solution, and the acid-base chamber used a 0.5 mol / L sodium sulfate (Na₂SO₄) solution. Under the influence of a DC electric field, the current was gradually increased, and the voltage values ​​across the bipolar membrane were measured. The data were plotted to obtain the current-voltage curve, as shown below. Figure 4As shown in the figure, the green curve represents the bipolar film data without the intermediate layer (0-BPM), and the blue curve represents the bipolar film data with MOF-808 as the intermediate layer (MOF808-based BPM). It can be seen that in the 0-122 mA cm⁻¹ range... -2 Within the current density range, the voltage of the MOF808-based BPM remains below 0-BPM, and at 100mA cm⁻¹... -2 At a current density of 1000 ohms, the transmembrane voltage of the MOF808-based BPM is only 1.23 V, which is 65.5% lower than the transmembrane voltage of 0-BPM (3.56 V).

[0027] The bipolar membrane was tested for its ability to catalytically degrade nerve agent mimics. The specific steps were as follows: The bipolar membrane was placed in a membrane stack device, with the cation exchange membrane layer facing the negative electrode and the anion exchange membrane layer facing the positive electrode. Cation exchange membranes and anion exchange membranes were placed on the left and right sides respectively to separate the electrode chamber and the acid-base chamber, forming a membrane stack with a structure of "+|cation exchange membrane|bipolar membrane|anion exchange membrane|-". Both the electrode chamber and the acid-base chamber used a 0.5 mol / L Na₂SO₄ solution. A 0.5 mol / L N-ethylmorpholine aqueous solution was added to the solution in the acid-base chamber, and the mixture was stirred vigorously for 30 min. Then, 0.4 mL of methyl parathion (DMNP) was added. A DC power supply was used, with the current density set to 100 mA cm⁻¹. -2 Every so often, 20 μL of the reaction solution was taken and diluted in a 0.15 mol / L N-ethylmorpholine aqueous solution. The absorbance of the bipolar membrane was measured using a UV-Vis spectrophotometer to obtain the conversion curve of DMNP, as shown below. Figure 5 As shown. The reaction rate constant is calculated by fitting the slope of the curve. k The reaction constant k and the half-life can be calculated using formulas (1) and (2).

[0028] (1) (2) The prepared MOF808-based BPM achieved an 80% conversion rate of DMNP within 64 min and a half-life of 25 min for catalytic degradation of DMNP, while the 0-BPM had a half-life of 363 min for catalytic degradation of DMNP. The introduction of MOF-808 improved the catalytic degradation efficiency by 14.52 times. Figure 6 The curves showing the pH change of the alkaline chamber solution over time during the degradation of MOF808-based BPM demonstrate excellent pH stability of the alkaline chamber solution. Experimental data show that the reaction chamber maintains a high OH content throughout the entire long-term degradation process. -Ion concentration. This phenomenon fully demonstrates that the bipolar membrane has a continuous water dissociation capability and can stably generate OH-. - Ions, and timely replenishment of OH- consumed during the degradation of DMNP. - Ions. Compared to traditional degradation methods, this bipolar membrane-based system effectively solves the key problem of alkali consumption, enabling the degradation reaction to proceed sustainably. Notably, this continuous OH- - The supplementation mechanism not only avoids pH fluctuations in the reaction system, but also provides a stable alkaline environment for the degradation reaction, thereby significantly improving degradation efficiency.

[0029] Example 2 The preparation method of the bipolar film in this embodiment includes the following steps: 1. Preparation of cation exchange membrane solution PVDF (5g), SSS (3.5g), and DVB (0.35mL) were stirred evenly in DMF. Then, AIBN (0.1g) was added under a nitrogen atmosphere, and the reaction was carried out at 75℃ for 10h to obtain the cation exchange membrane solution (PVDF-g-SSS). The membrane solution was uniformly coated on a glass plate and dried at 70℃ for 8h to obtain the cation exchange membrane solution.

[0030] 2. Preparation of the intermediate interface layer solution Prepare an 8wt% aqueous solution of polyethyleneimine, add 0.2g of UiO-66-NH2, and stir until evenly dispersed to obtain an intermediate interface layer solution.

[0031] 3. Preparation of anion exchange membrane solution PPO (24g) was added to chlorobenzene and stirred until dissolved. Then, NBS (33g) and AIBN (3.3g) were added, and the mixture was heated to 150℃ under a nitrogen atmosphere for free radical polymerization. The reaction was terminated after 8 hours. The cooled reaction solution was poured into ethanol, filtered, and dried to obtain a crude product. The crude product was redissolved in DCM, poured into ethanol, filtered, and dried to obtain BPPO with a bromination degree of 60%. BPPO (6g) was dissolved in NMP, and DMI (5g) was added. The reaction was terminated after 10 hours at 75℃. 3% UiO-66-NH2 was added to the reaction solution (PPO-DIM) to obtain anion exchange membrane solution.

[0032] 4. Preparation of bipolar films The cation exchange membrane solution was extended onto a glass plate and dried at 80°C on a flat plate heater to obtain a cation exchange membrane; 0.1 mL of intermediate interface layer solution was uniformly sprayed onto the surface of the cation exchange membrane and dried at 80°C on a flat plate heater; the anion exchange membrane solution was extended onto the surface of the intermediate layer and dried at 80°C on a flat plate heater to obtain a bipolar membrane.

[0033] Current-voltage curves of the bipolar film were tested, such as... Figure 7 As shown in the figure, the green curve represents the bipolar film data without the intermediate layer (0-BPM), and the blue curve represents the bipolar film data with UiO-66-NH2 as the intermediate layer (UiO-based BPM). It can be seen that in the 0-122 mA cm⁻¹ range... -2 Within the current density range, the voltage of the UiO-based BPM remains below 0-BPM, and at 100 mA cm⁻¹ -2 At a current density of 0-BPM, the transmembrane voltage of UiO-based BPM is only 2.12V, which is 40.4% lower than that of 0-BPM.

[0034] The bipolar membrane was tested for its ability to catalyze the degradation of nerve agent mimics, and the conversion curve of DMNP was obtained, as shown in the figure. Figure 8 As shown, the prepared UiO-based BPM achieved a DMNP conversion rate of 52% within 64 min and a catalytic degradation half-life of 57.8 min for DMNP, which is 6.3 times higher than that of 0-BPM.

[0035] The permeation performance of the bipolar membranes in Examples 1 and 2 was tested, and the specific steps were as follows: The bipolar membrane samples were fixed above a permeation cell containing a permeate (water, DMMP, or CEPS), placed in a test chamber at 35°C and 10% RH, and weighed at regular intervals. After the weight loss (W) became constant, a weight-time curve was obtained by measuring the weight of the permeation cell. The vapor transfer rate (gm³) was also measured. -2 24h -1 (VTR) and vapor permeability (VP, mol m) -1 s -1 The selectivity is calculated using formulas (3) and (4). The ratio of water to DMMP or CEPS vapor is defined as the selectivity and is calculated using formula (5). Three parallel tests were performed on each membrane to ensure the accuracy of the results.

[0036] (3) (4) (5) in, t For testing time, A The area of ​​the sample to be tested. L The thickness is the sample thickness.

[0037] The test results are shown in Table 1. It can be seen that the WVTR of both the bipolar films MOF808-based BPM and UiO-based BPM with added MOF intermediate layers is greater than 2000 gm. -2 24h -1 The moisture permeability requirements of chemical protective clothing are met, and the water vapor permeability (VP) values ​​are increased by 79.8% and 49.1% respectively compared to 0-BPM. The DMMP vapor transmission rates of MOF808-based BPM and UiO-based BPM are 1.80 × 10⁻⁶. -9 mol s -1 m -1 and 2.23×10 -9 mol s -1 m -1 All were lower than those of the PVDF-g-SSS cation exchange membrane (2.33×10). -9 mol s -1 m-1), which is higher than that of PPO-DIM anion exchange membrane (0.2×10). -9 mol s -1 m -1 The vapor permeability test results of CEPS showed that the CEPS vapor permeability of MOF808-based BPM and UiO-based BPM were 0.19×10⁻⁶. -9 mol s -1 m -1 and 0.26×10 -9 mol s -1 m -1 Slightly higher than PVDF-g-SSS cation exchange membrane (0.17×10⁻⁶). - 9 mol s -1 m -1 ), while lower than PPO-DIM anion exchange membrane (0.523×10), -9 mol s -1 m -1 This excellent selectivity is likely due to the hydrophilic phase formed by the aggregation of interconnected sulfonic acid groups and imidazole groups, which allows water transport, while hydrophobic CWAs analogs are repelled by the water channels, resulting in low absorption rates and thus hindering the transport of DMMP and CEPS. Furthermore, MOFs possess a uniform microporous structure, with dimensions slightly larger than the dynamic diameter of water molecules but much smaller than the molecular size of DMMP and CEPS. Therefore, water molecules can diffuse rapidly through the pores of MOFs, while larger DMMP and CEPS molecules are blocked by steric hindrance.

[0038] Table 1. VTR, VP, and membrane selectivity of water and DMMP

[0039] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a bipolar membrane for degrading harmful chemicals, characterized in that, The bipolar film preparation method includes the following steps: S1. Sulfonic acid type polyvinylidene fluoride cation exchange membrane solution is cast onto a glass plate and heated to dry to obtain a cation exchange membrane; S2. A metal-organic framework (MOF) is uniformly dispersed in an aqueous solution of polyethyleneimine to obtain an intermediate interface layer solution. The intermediate interface layer solution is sprayed onto the surface of a cation exchange membrane and then heated and dried to obtain a cation exchange membrane with an intermediate interface layer. S3. The imidazole-type polyphenylene ether anion exchange membrane solution is extended onto the intermediate interface layer and heated and dried to obtain a bipolar membrane consisting of a cation exchange membrane, an anion exchange membrane, and an intermediate interface layer.

2. The method for preparing a bipolar membrane for degrading harmful chemicals as described in claim 1, characterized in that, In steps S1 to S3, the product is heated and dried on a flat plate heater at a temperature of 50 to 90°C.

3. The method for preparing a bipolar membrane for degrading harmful chemicals as described in claim 1, characterized in that, In step S1, the thickness of the cation exchange membrane is 20~100μm.

4. The method for preparing a bipolar membrane for degrading harmful chemicals as described in claim 1, characterized in that, In step S3, the thickness of the anion exchange membrane is 20~100μm.

5. The method for preparing a bipolar membrane for degrading harmful chemicals as described in claim 1, characterized in that, In step S2, MOF is one of MOF-808, UiO-66, and UiO-66-NH2.

6. The method for preparing a bipolar membrane for degrading harmful chemicals as described in claim 1, characterized in that, In step S2, the amount of intermediate interface layer solution sprayed onto the surface of the cation exchange membrane is 0.05~0.8 mL.

7. The method for preparing a bipolar membrane for degrading harmful chemicals as described in claim 1, characterized in that, In step S1, the preparation method of sulfonic acid type polyvinylidene fluoride cation exchange membrane solution is as follows: polyvinylidene fluoride (PVDF), sodium p-styrene sulfonate (SSS), and divinylbenzene (DVB) are added to N,N-dimethylformamide (DMF), stirred and dissolved, and then azobisisobutyronitrile (AIBN) initiator is added. The amount of AIBN is 1-5 wt% of the mass of SSS. The temperature is raised to 50-90℃, and a free radical polymerization reaction is carried out under a nitrogen atmosphere. The reaction is terminated after 6-14 hours to obtain sulfonic acid type polyvinylidene fluoride cation exchange membrane solution PVDF-g-SSS.

8. The method for preparing a bipolar membrane for degrading harmful chemicals as described in claim 1, characterized in that, In step S2, the intermediate interface layer solution is prepared by: preparing a 1-10 wt% aqueous solution of polyethyleneimine, adding MOF and stirring for 6-24 h to disperse it evenly, wherein the content of MOF is 1-10 wt% of the content of polyethyleneimine, thereby obtaining the intermediate interface layer solution.

9. The method for preparing a bipolar membrane for degrading harmful chemicals as described in claim 1, characterized in that, In step S3, the preparation method of the imidazole-type polyphenylene ether anion exchange membrane solution is as follows: Polyphenylene ether (PPO) is added to chlorobenzene, stirred and dissolved, and then N-bromosuccinimide (NBS) and azobisisobutyronitrile (AIBN) are added. The amount of AIBN added is 2-10 wt% of the mass of NBS. The temperature is raised to 100-160℃, and a free radical polymerization reaction is carried out under a nitrogen atmosphere. The reaction is terminated after 6-12 hours. The cooled reaction solution is poured into ethanol and filtered and dried to obtain a crude product. The crude product is redissolved in dichloromethane (DCM), poured into ethanol, filtered and dried to obtain brominated polyphenylene ether (BPPO). The degree of bromination of BPPO is 20-50%. BPPO is dissolved in N-methylpyrrolidone (NMP), and 1,2-dimethylimidazolium (DMI) is added. The temperature is raised to 60-90℃, and the reaction is terminated after 6-12 hours to obtain the imidazole-type polyphenylene ether anion exchange membrane solution PPO-DIM.

10. A bipolar membrane for degrading harmful chemicals, characterized in that, The bipolar film is prepared by the method described in any one of claims 1 to 9.

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