Bipolar membrane, electrodialysis device, preparation method and application

Abstract

The present invention discloses a bipolar membrane, an electrodialysis device, a preparation method, and applications. The bipolar membrane comprises a cation exchange membrane, an intermediate layer, and an anion exchange membrane stacked in sequence, wherein the intermediate layer comprises nitrogen-doped graphene oxide. The bipolar membrane exhibits high water dissociation efficiency, a high acid and base production rate, a low voltage required for the water dissociation process, and low energy consumption.

Description

Technical Field

[0001] The present application belongs to the field of bipolar membrane technology, and specifically relates to a bipolar membrane, an electrodialysis device, a preparation method and applications. Background Art

[0002] Bipolar membrane is a new type of ion exchange composite membrane, which is usually composed of a cation exchange layer, an intermediate layer and an anion exchange layer. The intermediate layer is usually a few nanometers thick, electrically neutral and contains a catalyst. Under the action of a DC electric field, the intermediate layer of the bipolar membrane can dissociate water to produce H + and OH - Subsequently, the generated H + and OH - Driven by the potential difference between the cathode and anode, the bipolar membrane migrates toward the cathode and anode, respectively. At the same time, water in the solution on both sides of the bipolar membrane enters the IL layer through the AEL and CEL to replenish the water consumption.

[0003] The bipolar membrane is the core component of a bipolar membrane electrodialysis device, and its performance has a decisive influence on the bipolar membrane electrodialysis process. Currently, the water dissociation efficiency of bipolar membranes is low, and the water dissociation voltage and energy consumption are high. Summary of the Invention

[0004] Aiming at the technical problems of low water dissociation efficiency, high water dissociation voltage and high energy consumption of existing bipolar membranes, a bipolar membrane, an electrodialysis device, a preparation method and applications are provided.

[0005] In some embodiments, a bipolar membrane is provided, comprising a cation exchange membrane, an intermediate layer, and an anion exchange membrane stacked in sequence, wherein the intermediate layer comprises nitrogen-doped graphene oxide.

[0006] In some embodiments, the bipolar membrane satisfies one or more of the following characteristics:

[0007] The loading amount of nitrogen-doped graphene oxide contained in the intermediate layer is 0.2 mg / cm 2 ~1.0mg / cm 2 ;

[0008] The molar percentage of nitrogen in the nitrogen-doped graphene oxide contained in the intermediate layer is 4% to 5%;

[0009] The particle size of the nitrogen-doped graphene oxide contained in the intermediate layer is less than or equal to 0.054 mm.

[0010] In some embodiments, the bipolar membrane satisfies one or more of the following characteristics:

[0011] The cation exchange membrane comprises sulfonated polysulfone, and the sulfonated polysulfone has a sulfonation degree of 35% to 50%;

[0012] The anion exchange membrane comprises quaternized polysulfone, and the quaternization degree of the quaternized polysulfone is 40% to 50%.

[0013] In some embodiments, a method for preparing a bipolar membrane is provided, comprising the following steps:

[0014] The cation exchange membrane is prepared by forming a film of the cation exchange membrane liquid on the substrate using a casting method;

[0015] loading nitrogen-doped graphene oxide onto the cation exchange membrane to form an intermediate layer comprising the nitrogen-doped graphene oxide on the cation exchange membrane;

[0016] The anion exchange membrane liquid is cast onto the surface of the intermediate layer away from the cation exchange membrane, and dried to form an anion exchange membrane on the surface of the intermediate layer away from the cation exchange membrane, thereby preparing a bipolar membrane.

[0017] In some embodiments, in the method for preparing the bipolar membrane, the cation exchange membrane liquid comprises sulfonated polysulfone and a first organic solvent; the anion exchange membrane liquid comprises quaternized polysulfone and a second organic solvent;

[0018] In some embodiments, the method for preparing the bipolar membrane satisfies one or more of the following characteristics:

[0019] In the cation exchange membrane solution, the ratio of the sulfonated polysulfone to the first organic solvent is 10 g: (50-75) mL, based on the feed amount;

[0020] In the anion exchange membrane solution, the ratio of the quaternized polysulfone to the second organic solvent is 10 g: (50-75) mL, based on the feed amount;

[0021] The first organic solvent and the second organic solvent each independently comprise one or more of dimethylformamide, dimethylacetamide and N-methylpyrrolidone;

[0022] The step of loading nitrogen-doped graphene oxide onto a cation exchange membrane comprises: mixing the nitrogen-doped graphene oxide with a third solvent to prepare an intermediate layer suspension, loading the intermediate layer suspension onto the cation exchange membrane, and performing a suction filtration process.

[0023] In some embodiments, in the method for preparing the bipolar membrane, the method for preparing the sulfonated polysulfone comprises the following steps:

[0024] In the presence of a fourth organic solvent, the first polysulfone is subjected to a sulfonation reaction with sulfuric acid, followed by alcohol precipitation and drying to prepare the sulfonated polysulfone;

[0025] Optionally, the preparation method of the sulfonated polysulfone meets one or more of the following characteristics:

[0026] Based on the feed amount, the ratio of the first polysulfone to the sulfuric acid is 10 g: (2-10) mL;

[0027] Calculated by feed amount, the ratio of the first polysulfone to the fourth organic solvent is 10 g: (100-150) mL;

[0028] The weight average molecular weight of the first polysulfone is 30 kDa to 40 kDa, and the number average molecular weight of the first polysulfone is 20 kDa to 30 kDa;

[0029] The fourth organic solvent comprises one or more of dichloroethane, dichloromethane and chloroform.

[0030] In some embodiments, in the method for preparing the bipolar membrane, the method for preparing the nitrogen-doped graphene oxide comprises the following steps:

[0031] adding graphene oxide powder to ammonia water, stirring the resulting suspension, performing solid-liquid separation, washing, and drying to prepare nitrogen-doped graphene oxide having a particle size of less than or equal to 0.054 mm;

[0032] Optionally, the method for preparing nitrogen-doped graphene oxide satisfies one or more of the following characteristics:

[0033] Calculated by the amount of feed, the volume mass ratio of the ammonia water to the graphene oxide is (0.8-2) mL / mg;

[0034] The concentration of the ammonia water is 0.2mol / L~0.3mol / L;

[0035] The obtained suspension is stirred at 30°C to 75°C.

[0036] The obtained suspension is subjected to a stirring step, wherein the stirring time is 4 h to 6 h;

[0037] The obtained suspension is subjected to a stirring step, and the stirring speed is 200 rpm-400 rpm.

[0038] In some embodiments, in the method for preparing the bipolar membrane, the method for preparing the quaternized polysulfone comprises the following steps:

[0039] In the presence of a fifth organic solvent, the second polysulfone is reacted with chloromethyl ethyl ether and anhydrous tin tetrachloride, followed by alcohol precipitation and drying to prepare chloromethylated polysulfone;

[0040] reacting the chloromethylated polysulfone with triethylamine in the presence of a sixth organic solvent, performing alcohol precipitation, and drying to prepare the quaternized polysulfone;

[0041] Optionally, the preparation method of the quaternized polysulfone satisfies one or more of the following characteristics:

[0042] Based on the feeding amount, the ratio of the second polysulfone to the fifth organic solvent is 10 g: (100-150) mL;

[0043] Based on the feed amount, the ratio of the second polysulfone to the chloromethyl ether is 10 g: (5-10) mL;

[0044] Based on the feed amount, the ratio of the second polysulfone to the anhydrous tin tetrachloride is 10 g: (1-2) mL;

[0045] Based on the amount of material added, the ratio of the chloromethylated polysulfone to the sixth organic solvent is 5 g: (100-200) mL;

[0046] Based on the amount of material added, the ratio of the chloromethylated polysulfone to the triethylamine solution is 5 g: (5-10) mL;

[0047] The weight average molecular weight of the second polysulfone is 30 kDa to 40 kDa, and the number average molecular weight of the second polysulfone is 20 kDa to 30 kDa;

[0048] The fifth organic solvent comprises one or more of dichloroethane, dichloromethane and chloroform;

[0049] The sixth organic solvent includes one or more of N-methylpyrrolidone, N,N-dimethylformamide, and N,N-dimethylacetamide.

[0050] In some embodiments, there is provided use of the bipolar membrane or the bipolar membrane prepared by the preparation method in water splitting or in preparing an electrodialysis device.

[0051] In some embodiments, an electrodialysis device is provided, comprising the bipolar membrane described above or the bipolar membrane prepared by the preparation method described above.

[0052] The bipolar membranes provided above have high water dissociation efficiency and high acid and base production rates. The water dissociation process requires low voltage and consumes low energy. The nitrogen-doped graphene oxide contained in the intermediate layer increases the water dissociation rate and hydrophilicity of the intermediate layer, thereby reducing the transmembrane voltage. The provided bipolar membrane preparation method is simple and allows for precise control of the intermediate layer content. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] In order to more clearly illustrate the technical solutions in the embodiments and examples of this application and to provide a more complete understanding of the application and its beneficial effects, the following briefly introduces the drawings required for use in the description of the embodiments or examples. Obviously, the drawings described below are only some embodiments of this application. Those skilled in the art can also derive other drawings based on these drawings without inventive effort.

[0054] Figure 1 is a schematic diagram of a process flow for preparing a bipolar membrane in one embodiment;

[0055] Figure 2 is a flow chart for preparing a bipolar membrane in one embodiment;

[0056] Figure 3 is a schematic diagram of a bipolar membrane in one embodiment;

[0057] Figure 4 : is a graph showing the X-ray photoelectron spectroscopy (XPS) test results of the elemental species of nitrogen-doped graphene oxide prepared in Example 1, wherein Intensity is the relative intensity and Binding energy is the binding energy;

[0058] Figure 5 is a cross-sectional SEM diagram of the bipolar membrane prepared in Example 1;

[0059] Figure 6 1 is a graph showing the bipolar membrane current-voltage performance test results of Example 1 and Comparative Example 1, wherein the blank sample is Comparative Example 1;

[0060] Figure 7 1 is a graph showing the bipolar membrane stability test results of Example 1 and Comparative Example 1, wherein the blank sample is Comparative Example 1;

[0061] Figure 8 1 is a graph showing the acid-base performance test results of the bipolar membranes of Example 1 and Comparative Example 1, wherein the blank sample is Comparative Example 1. DETAILED DESCRIPTION

[0062] To facilitate understanding of the present invention, the present invention will be described more fully below with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the accompanying drawings. However, the present invention may be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the present disclosure.

[0063] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one skilled in the art to which this invention pertains. The terms used in this specification of the present invention are for the purpose of describing specific embodiments only and are not intended to limit the present invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0064] Unless otherwise specified or incompatible herewith, the terms and phrases used herein shall have the following meanings:

[0065] The terms "and / or", "or / and", and "and / or" used in this application include any one of two or more related listed items, and also include any and all combinations of the related listed items, and the said any and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. It should be noted that when at least three items are connected by at least two conjunctions selected from "and / or", "or / and", and "and / or", it should be understood that in this application, the technical solution undoubtedly includes technical solutions that are all connected by "logical and", and undoubtedly includes technical solutions that are all connected by "logical or". For example, "A and / or B" includes three parallel solutions: A, B and "a combination of A and B".

[0066] In this application, "plurality", "multiple", "multiple times", "multiples", etc., unless otherwise specified, refer to a quantity greater than or equal to 2. For example, "one or more" means one or more than or equal to two.

[0067] The terms "combination thereof", "any combination thereof", "any combination thereof" and the like used in this application include all suitable combinations of any two or more of the listed items.

[0068] In this application, the "suitable" mentioned in "suitable combination", "suitable method", "any suitable method", etc. is based on the ability to implement the technical solution of this application, solve the technical problems of this application, and achieve the expected technical effects of this application.

[0069] In this application, "preferred", "better", "more preferred" and "suitable" are only used to describe implementation methods or examples with better effects. It should be understood that they do not constitute a limitation on the scope of protection of this application.

[0070] In this application, "further", "further", "particularly" and the like are used for descriptive purposes to indicate differences in content, but should not be understood as limiting the scope of protection of this application.

[0071] In this application, the terms "optionally," "optional," and "optional" mean optional or dispensable, i.e., they refer to either option being selected from two parallel options: "with" or "without." If a technical solution contains multiple "optional" clauses, each "optional" clause is independent unless otherwise specified and there are no contradictions or constraints.

[0072] In the present invention, in the "first aspect," "second aspect," "third aspect," "fourth aspect," etc., the terms "first," "second," "third," "fourth," etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or quantity, nor as implicitly indicating the importance or quantity of the technical features indicated. Furthermore, "first," "second," "third," "fourth," etc. serve only as non-exhaustive enumeration and description and should be understood not to constitute a closed-ended limitation on quantity.

[0073] In this application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0074] In this application, when referring to a numerical interval (i.e., a numerical range), unless otherwise specified, the optional numerical distribution is considered continuous within the above numerical interval and includes the two numerical endpoints of the numerical range (i.e., the minimum and maximum values), as well as each numerical value between the two numerical endpoints. Unless otherwise specified, when a numerical interval refers only to integers within the numerical interval, it includes the two endpoint integers of the numerical range, as well as each integer between the two endpoints. In this article, it is equivalent to directly listing each integer, such as t is an integer selected from 1 to 10, indicating that t is any integer selected from the group of integers consisting of 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10. In addition, when multiple ranges are provided to describe features or characteristics, these ranges can be merged. In other words, unless otherwise specified, the ranges disclosed herein should be understood to include any and all subranges included therein.

[0075] Unless otherwise specified, the temperature parameters in this application allow for both constant temperature treatment and temperature fluctuations within a certain temperature range. It should be understood that the constant temperature treatment allows for temperature fluctuations within the accuracy range of instrument control. Fluctuations within ranges such as ±5°C, ±4°C, ±3°C, ±2°C, and ±1°C are permitted.

[0076] In this application, % (w / w) and wt% both refer to weight percentage, % (v / v) refers to volume percentage, and % (w / v) refers to mass volume percentage.

[0077] The "room temperature" in this application generally refers to 5°C to 30°C, preferably 25±5°C.

[0078] The bipolar membrane is the core component of a bipolar membrane electrodialysis device. Its performance has a decisive influence on the bipolar membrane electrodialysis process. An ideal bipolar membrane should have high selectivity, reduced voltage, low energy consumption, stable mechanical properties, and a long service life.

[0079] The modification of bipolar membranes can be divided into modification of bipolar membrane materials and modification of the intermediate layer. Regardless of the modification method adopted, improving the water dissociation efficiency of the intermediate layer and reducing the water dissociation voltage and energy consumption of the bipolar membrane are the key to the current research and development of bipolar membranes.

[0080] In some embodiments, a bipolar membrane is provided, comprising a cation exchange membrane, an intermediate layer, and an anion exchange membrane stacked in sequence, wherein the intermediate layer comprises nitrogen-doped graphene oxide.

[0081] In some embodiments, the bipolar membrane provided has a nitrogen-doped graphene oxide loading of 0.2 mg / cm 2 ~1.0mg / cm 2 For example, the loading of nitrogen-doped graphene oxide is 0.2 mg / cm 2 , 0.3mg / cm 2 , 0.4mg / cm 2 , 0.5mg / cm 2 , 0.6mg / cm 2 , 0.7mg / cm 2 , 0.8mg / cm 2 , 0.9mg / cm 2 , 1.0mg / cm 2 Or selected from the range consisting of any two of the aforementioned ratios.

[0082] Too low a content of nitrogen-doped graphene oxide will result in a low content of hydrophilic groups in the bipolar membrane, which will lead to a slow water dissociation catalytic rate and poor bipolar membrane performance; while too much content will thicken the intermediate layer, resulting in a slow water dissociation catalytic rate and poor bipolar membrane performance.

[0083] In some embodiments, the molar percentage of nitrogen in the nitrogen-doped graphene oxide contained in the intermediate layer is 4% to 5%. For example, the molar percentage of nitrogen in the nitrogen-doped graphene oxide is 4%, 4.1%, 4.2%, 4.3%, 4.4%, 4.5%, 4.6%, 4.7%, 4.8%, 4.9%, 5% or a range selected from any two of the foregoing ratios.

[0084] The nitrogen-doped graphene oxide used in the middle layer can not only increase the water dissociation rate and hydrophilicity of the middle layer, thereby reducing the transmembrane voltage, but also increase the acid and alkali production rate and reduce energy consumption.

[0085] In some embodiments, the particle size of the nitrogen-doped graphene oxide contained in the intermediate layer is less than or equal to 0.054 mm.

[0086] In some embodiments, a bipolar membrane is provided wherein the cation exchange membrane comprises sulfonated polysulfone.

[0087] In some embodiments, the sulfonated polysulfone contained in the cation exchange membrane has a sulfonation degree of 35% to 50%.

[0088] Without limitation, in some embodiments, the cation exchange membrane comprises a sulfonated polysulfone having a repeating unit as shown below: .

[0089] In some embodiments, a bipolar membrane is provided wherein the anion exchange membrane comprises quaternized polysulfone.

[0090] In some embodiments, the quaternized polysulfone included in the anion exchange membrane has a quaternization degree of 40% to 50%.

[0091] Without limitation, in some embodiments, the anion exchange membrane comprises a quaternized polysulfone having a repeating unit as shown below:

[0092] .

[0093] In some embodiments, a method for preparing a bipolar membrane is provided, comprising the following steps:

[0094] The cation exchange membrane is prepared by forming a film of the cation exchange membrane liquid on the substrate using a casting method;

[0095] loading nitrogen-doped graphene oxide onto a cation exchange membrane to form an intermediate layer comprising nitrogen-doped graphene oxide on the cation exchange membrane;

[0096] The anion exchange membrane liquid is cast onto the surface of the middle layer away from the cation exchange membrane, and dried to form an anion exchange membrane on the surface of the middle layer away from the cation exchange membrane, thereby preparing a bipolar membrane. Figure 1 .

[0097] Without limitation, the bipolar membrane preparation flow chart can be found in Figure 2 .

[0098] Figure 3 Schematic diagram of a bipolar membrane in one embodiment.

[0099] In some embodiments, the cation exchange membrane solution comprises sulfonated polysulfone and a first organic solvent.

[0100] In some embodiments, the anion exchange membrane solution comprises quaternized polysulfone and a second organic solvent.

[0101] In some embodiments, in the provided method for preparing a bipolar membrane, in the cation exchange membrane solution, based on the feed amount, the ratio of sulfonated polysulfone to the first organic solvent is 10 g: (50-75) mL, for example, 10 g: 50 mL, 10 g: 55 mL, 10 g: 60 mL, 10 g: 65 mL, 10 g: 70 mL, 10 g: 75 mL, or a range selected from any two of the foregoing ratios.

[0102] In some embodiments, in the method for preparing a bipolar membrane provided, in the anion exchange membrane solution, the ratio of the quaternized polysulfone to the second organic solvent, calculated in g / mL, based on the feed amount, is 10:(50-75), for example, 10 g:50 mL, 10 g:55 mL, 10 g:60 mL, 10 g:65 mL, 10 g:70 mL, 10 g:75 mL, or a range selected from any two of the foregoing ratios.

[0103] In some embodiments, in the provided method for preparing a bipolar membrane, the first organic solvent and the second organic solvent each independently comprise one or more of dimethylformamide, dimethylacetamide, and N-methylpyrrolidone.

[0104] In some embodiments, in the provided method for preparing a bipolar membrane, the step of loading nitrogen-doped graphene oxide onto a cation exchange membrane includes mixing nitrogen-doped graphene oxide with a third solvent to prepare an intermediate layer suspension, loading the intermediate layer suspension onto the cation exchange membrane, and performing a filtration treatment.

[0105] In some embodiments, in the method for preparing a bipolar membrane provided, in the step of loading nitrogen-doped graphene oxide onto a cation exchange membrane, the third solvent comprises water.

[0106] In some embodiments, in the provided method for preparing a bipolar membrane, in the step of loading nitrogen-doped graphene oxide onto a cation exchange membrane, the ratio of nitrogen-doped graphene oxide to the third solvent is (2.5-12.5) mg:100 mL, based on the feed amount.

[0107] The middle layer is loaded onto the cation exchange membrane by filtration and is not easy to stratify. The added nitrogen-doped graphene oxide increases the active sites for water dissociation catalysis, accelerates the water dissociation process, greatly reduces the water dissociation voltage, and significantly improves the acid-base production performance.

[0108] In some embodiments, the volume ratio of the cation exchange membrane liquid to the anion exchange membrane liquid is 2:(1-3).

[0109] In some embodiments, in the method for preparing a bipolar membrane provided, the method for preparing sulfonated polysulfone comprises the following steps:

[0110] In the presence of a fourth organic solvent, the first polysulfone is subjected to a sulfonation reaction with sulfuric acid, followed by alcohol precipitation and drying to prepare the sulfonated polysulfone.

[0111] In some embodiments, the sulfonation reaction is performed for 4 to 8 hours, for example, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, or a range selected from any two of the foregoing values. Performing the sulfonation reaction for too short a time may result in a low degree of polysulfone sulfonation, resulting in poor performance of the prepared bipolar membrane.

[0112] In some embodiments, in the method for preparing a bipolar membrane provided, in the method for preparing a sulfonated polysulfone, based on the feed amount, the ratio of the first polysulfone to sulfuric acid is 10 g: (2-10) mL, for example, 10 g: 2 mL, 10 g: 3 mL, 10 g: 4 mL, 10 g: 5 mL, 10 g: 6 mL, 10 g: 7 mL, 10 g: 8 mL, 10 g: 9 mL, 10 g: 10 mL, or a range selected from any two of the foregoing ratios.

[0113] In some embodiments, in the method for preparing a bipolar membrane provided, in the method for preparing a sulfonated polysulfone, the ratio of the first polysulfone to the fourth organic solvent, calculated on a feed basis, is 10 g:(100-150) mL, for example, 10 g:100 mL, 10 g:110 mL, 10 g:120 mL, 10 g:130 mL, 10 g:140 mL, 10 g:150 mL, or a range selected from any two of the foregoing ratios.

[0114] In some embodiments, in the method for preparing a bipolar membrane, in the method for preparing sulfonated polysulfone, the weight average molecular weight of the first polysulfone is 30 kDa to 40 kDa, and the number average molecular weight of the first polysulfone is 20 kDa to 30 kDa.

[0115] Without limitation, in some embodiments, the repeating unit of the first polysulfone is as follows: .

[0116] In some embodiments, in the method for preparing a bipolar membrane and the method for preparing sulfonated polysulfone, the fourth organic solvent comprises one or more of dichloroethane, dichloromethane, and chloroform.

[0117] In some embodiments, in the provided bipolar membrane preparation method, the nitrogen-doped graphene oxide preparation method comprises the following steps:

[0118] Graphene oxide powder is added to ammonia water, and the obtained suspension is stirred, solid-liquid separated, washed, and dried to prepare nitrogen-doped graphene oxide with a particle size of less than or equal to 0.054 mm.

[0119] In a non-limiting manner, nitrogen-doped graphene oxide is prepared using a low-temperature method. The above-mentioned nitrogen-doped graphene oxide preparation method is simple, and the obtained nitrogen-doped graphene oxide has good stability and high water dissociation properties.

[0120] In some embodiments, in the method for preparing a bipolar membrane provided, in the method for preparing nitrogen-doped graphene oxide, the ratio of graphene oxide to ammonia water is (50-100) mg: (30-90) mL, based on the amount of material fed, for example, 50 mg:30 mL, 50 mg:60 mL, 50 mg:90 mL, 75 mg:30 mL, 75 mg:60 mL, 75 mg:90 mL, 100 mg:30 mL, 100 mg:60 mL, 100 mg:90 mL, or a range selected from any two of the foregoing ratios.

[0121] In some embodiments, in the method for preparing a bipolar membrane provided, in the method for preparing nitrogen-doped graphene oxide, the volume mass ratio of ammonia water to graphene oxide, calculated on the basis of the feeding amount, is (0.8~2.0) mL / mg, for example, 0.8 mL / mg, 0.9 mL / mg, 1.0 mL / mg, 1.1 mL / mg, 1.2 mL / mg, 1.3 mL / mg, 1.4 mL / mg, 1.5 mL / mg, 1.6 mL / mg, 1.7 mL / mg, 1.8 mL / mg, 1.9 mL / mg, 2.0 mL / mg, or a range selected from any two of the foregoing values.

[0122] In some embodiments, in the provided bipolar membrane preparation method, in the nitrogen-doped graphene oxide preparation method, the concentration of ammonia water is 0.2 mol / L to 0.3 mol / L.

[0123] In some embodiments, in the provided method for preparing a bipolar membrane, in the method for preparing nitrogen-doped graphene oxide, the obtained suspension is stirred at 30°C to 75°C in the stirring step, for example, at 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C or a range selected from any two ratios of the foregoing.

[0124] In some embodiments, in the provided bipolar membrane preparation method, in the nitrogen-doped graphene oxide preparation method, the obtained suspension is stirred for a time of 4 h to 6 h, for example, the stirring time is 4 h, 5 h, 6 h or a range selected from any two of the foregoing ratios.

[0125] In some embodiments, in the provided method for preparing a bipolar membrane, in the method for preparing nitrogen-doped graphene oxide, the obtained suspension is stirred at a speed of 200 rpm-400 rpm, for example, 200 rpm, 250 rpm, 300 rpm, 350 rpm, 400 rpm or a range selected from any two of the foregoing ratios.

[0126] In some embodiments, in the method for preparing a bipolar membrane provided, the method for preparing quaternized polysulfone comprises the following steps:

[0127] In the presence of a fifth organic solvent, the second polysulfone is reacted with chloromethyl ethyl ether and anhydrous tin tetrachloride, followed by alcohol precipitation and drying to prepare chloromethylated polysulfone;

[0128] In the presence of a sixth organic solvent, the chloromethylated polysulfone is reacted with triethylamine, followed by alcohol precipitation and drying to prepare the quaternized polysulfone.

[0129] In some embodiments, the second polysulfone, chloromethyl ethyl ether, and anhydrous tin tetrachloride are reacted for 2 hours to 4 hours, for example, 2 hours, 3 hours, or 4 hours.

[0130] In some embodiments, the reaction time of the chloromethylated polysulfone and triethylamine is 20 hours to 30 hours, for example, 20 hours, 25 hours, or 30 hours. When the chloromethylated polysulfone is quaternized, a reaction time that is too short will result in a low degree of quaternization and poor performance of the prepared bipolar membrane.

[0131] In some embodiments, in the method for preparing a bipolar membrane provided, in the method for preparing a quaternized polysulfone, the ratio of the second polysulfone to the fifth organic solvent, calculated in g / mL, based on the feed amount, is 10 g: (100-150) mL, for example, 10 g: 100 mL, 10 g: 110 mL, 10 g: 120 mL, 10 g: 130 mL, 10 g: 140 mL, 10 g: 150 mL, or a range selected from any two of the foregoing ratios.

[0132] In some embodiments, in the method for preparing a bipolar membrane provided, in the method for preparing a quaternized polysulfone, the ratio of the second polysulfone to chloromethyl ethyl ether, calculated in g / mL, is 10 g: (5-10) mL, for example, 10 g: 5 mL, 10 g: 6 mL, 10 g: 7 mL, 10 g: 8 mL, 10 g: 9 mL, 10 g: 10, or a range selected from any two of the foregoing ratios.

[0133] In some embodiments, in the method for preparing a bipolar membrane, in the method for preparing a quaternized polysulfone, the ratio of the second polysulfone to anhydrous tin tetrachloride is 10 g: (1-2) mL, calculated in g / mL.

[0134] Without limitation, in some embodiments, in the method for preparing a bipolar membrane provided, in the method for preparing quaternized polysulfone, the repeating unit of the chloromethylated polysulfone is as follows: .

[0135] In some embodiments, in the method for preparing a bipolar membrane provided, in the method for preparing a quaternized polysulfone, based on the amount of material fed, the ratio of the chloromethylated polysulfone to the sixth organic solvent is 5 g: (100-200) mL, for example, 5 g: 100 mL, 5 g: 110 mL, 5 g: 120 mL, 5 g: 130 mL, 5 g: 140 mL, 5 g: 150 mL, 5 g: 160 mL, 5 g: 170 mL, 5 g: 180 mL, 5 g: 190 mL, 5 g: 200 mL, or a range selected from any two of the foregoing ratios.

[0136] In some embodiments, in the method for preparing a bipolar membrane provided, in the method for preparing a quaternized polysulfone, the ratio of the chloromethylated polysulfone to the triethylamine solution is 5 g: (5-10) mL, based on the feed amount, for example, 5 g: 5 mL, 5 g: 6 mL, 5 g: 7 mL, 5 g: 8 mL, 5 g: 9 mL, 5 g: 10 mL, or a range selected from any two of the foregoing ratios.

[0137] In some embodiments, in the method for preparing a bipolar membrane provided herein, in the method for preparing the quaternized polysulfone, the second polysulfone has a weight average molecular weight of 30 kDa to 40 kDa, and a number average molecular weight of 20 kDa to 30 kDa.

[0138] Without limitation, in some embodiments, the repeating unit of the second polysulfone is as follows: .

[0139] In some embodiments, in the provided method for preparing a bipolar membrane and the method for preparing a quaternized polysulfone, the fifth organic solvent comprises one or more of dichloroethane, dichloromethane, and chloroform.

[0140] In some embodiments, in the method for preparing a bipolar membrane and the method for preparing quaternized polysulfone, the sixth organic solvent comprises one or more of N-methylpyrrolidone, N,N-dimethylformamide, and N,N-dimethylacetamide.

[0141] The bipolar membrane prepared by the above method can increase the water dissociation rate and hydrophilicity of the middle layer, thereby reducing the transmembrane voltage and increasing the acid and alkali production rate; the bipolar membrane is prepared by the casting method, in which the casting amount of the middle layer can be precisely controlled, and the preparation process is simple. The nitrogen-doped graphene oxide used can not only increase the water dissociation rate and hydrophilicity of the middle layer, thereby reducing the transmembrane voltage, but also increase the acid and alkali production rate and reduce energy consumption.

[0142] In some embodiments, there is provided use of the aforementioned bipolar membrane or the bipolar membrane prepared by the aforementioned preparation method in water dissociation or in preparing an electrodialysis device.

[0143] In some embodiments, an electrodialysis device is provided, comprising the aforementioned bipolar membrane or the bipolar membrane prepared by the aforementioned preparation method.

[0144] The bipolar membrane or electrodialysis device provided above can be applied to high-salt water treatment to achieve zero-discharge effect.

[0145] The present invention is further described below with reference to specific examples and comparative examples.

[0146] 1. Preparation of bipolar membrane

[0147] Example 1

[0148] (1) Preparation of sulfonated polysulfone: 10 g of polysulfone was placed in a three-necked flask, 100 ml of dichloroethane was added, and the mixture was stirred at 50°C until dissolved. 10 ml of concentrated sulfuric acid was added and the mixture was allowed to react for 5 h. After the reaction was complete, the reaction solution was poured into ethanol to precipitate the solution, and the solution was repeatedly washed with pure water and ethanol, and then dried at 70°C for 48 h.

[0149] (2) Preparation of cation exchange membrane liquid: Take 2g of dried sulfonated polysulfone powder, place it in a single-necked flask, add 10ml of dimethylformamide solution, stir at 50℃ until dissolved, and let it stand for 24h to degas.

[0150] (3) Preparation of nitrogen-doped graphene oxide: 50 mg of graphene oxide powder was added to 60 mL of 25% ammonia water. The resulting suspension was magnetically stirred at 75°C until it became a muddy state. The precipitate was separated by high-speed centrifugation at 4200 r / min for 8 min, and washed repeatedly with ethanol and distilled water three times to obtain a black solid. The solid was dried in a vacuum drying oven at 50°C. The dried product was ground into powder using an agate mortar and sieved with a standard test sieve (pore size d = 0.054 mm).

[0151] (4) Preparation of intermediate layer suspension: Take 5 mg of nitrogen-doped graphene oxide powder, place it in a beaker, add 100 ml of pure water, and stir vigorously to make it evenly dispersed.

[0152] (5) Preparation of chloromethylated polysulfone: 10 g of polysulfone was placed in a three-necked flask, 100 ml of dichloroethane was added, and the mixture was stirred at 50°C until dissolved. 5 mL of chloromethyl ether and 1 mL of anhydrous tin tetrachloride were added and the mixture was allowed to react for 2 h. After the reaction was complete, the reaction solution was poured into ethanol to precipitate the solution, and the solution was repeatedly washed with pure water and ethanol, and then dried at 70°C for 48 h.

[0153] (6) Preparation of quaternized polysulfone: 5 g of chloromethylated polysulfone was placed in a three-necked flask, 100 mL of N-methylpyrrolidone was added, and the mixture was stirred at 50°C until dissolved. 6 mL of triethylamine solution was added and the mixture was allowed to react for 24 h. After the reaction was complete, the reaction solution was poured into ethanol to precipitate, and the mixture was repeatedly washed with pure water and ethanol, and then dried at 70°C for 48 h.

[0154] (7) Preparation of anion exchange membrane liquid: Take 2 g of dried quaternized polysulfone powder, place it in a single-necked flask, add 10 ml of dimethylformamide solution, stir at 50 °C until dissolved, and let it stand for 24 h to degas.

[0155] (8) Preparation of bipolar membrane: Take a clean glass plate, pour the cation exchange membrane liquid on the glass plate, scrape the membrane with a 200μm scraper, and place it on a 70℃ hot plate to heat for 3 hours. Immerse it in pure water and wait for the membrane to fall off naturally to obtain a cation exchange membrane. Take 50ml of the intermediate layer suspension and filter it onto the cation exchange membrane using a suction filter to obtain a cation exchange membrane containing an intermediate layer. The effective area of ​​the intermediate layer is 12.56cm 2 The cation exchange membrane containing the intermediate layer was re-pasted onto the glass plate, and the anion exchange membrane solution was cast thereon, which was then placed on a heating plate at 50°C and heated for 3 hours to obtain a bipolar membrane.

[0156] Example 2

[0157] The difference from Example 1 is that, in the preparation of the intermediate layer suspension, 2.5 mg of nitrogen-doped graphene oxide powder was taken and placed in a beaker, and 100 ml of pure water was added, and the mixture was stirred vigorously to disperse it evenly.

[0158] Example 3

[0159] The difference from Example 1 is that, in the preparation of the intermediate layer suspension, 7.5 mg of nitrogen-doped graphene oxide powder was taken and placed in a beaker, and 100 ml of pure water was added, and the mixture was stirred vigorously to disperse it evenly.

[0160] Example 4

[0161] The difference from Example 1 is that the intermediate layer suspension was prepared as follows: 10 mg of nitrogen-doped graphene oxide powder was placed in a beaker, and 100 ml of pure water was added, and the mixture was stirred vigorously to disperse the mixture evenly.

[0162] Example 5

[0163] The difference from Example 1 is that, in the preparation of the intermediate layer suspension, 12.5 mg of nitrogen-doped graphene oxide powder was taken and placed in a beaker, and 100 ml of pure water was added, and the mixture was stirred vigorously to disperse it evenly.

[0164] Example 6

[0165] The difference from Example 1 is that the sulfonated polysulfone was prepared by placing 10g of polysulfone in a three-necked flask, adding 100ml of dichloroethane, and stirring at 50°C until dissolved. 5ml of concentrated sulfuric acid was then added and allowed to react for 5 hours. After the reaction was complete, the reaction solution was poured into ethanol to precipitate, washed repeatedly with pure water and ethanol, and then dried at 70°C for 48 hours.

[0166] Example 7

[0167] The difference from Example 1 is that the chloromethylated polysulfone was prepared by placing 10g of polysulfone in a three-necked flask, adding 100ml of dichloroethane, and stirring at 50°C until dissolved. 10ml of chloroacetyl chloride and 2ml of anhydrous tin tetrachloride were then added and allowed to react for 2 hours. After the reaction was complete, the reaction solution was poured into ethanol to precipitate, washed repeatedly with pure water and ethanol, and then dried at 70°C for 48 hours.

[0168] Example 8

[0169] The difference from Example 1 is that the quaternized polysulfone was prepared by placing 5 g of chloromethylated polysulfone in a three-necked flask, adding 100 mL of N-methylpyrrolidone, and stirring at 50°C until dissolved. 3 mL of trimethylamine solution was then added and allowed to react for 24 hours. After the reaction was complete, the reaction solution was poured into ethanol to precipitate, washed repeatedly with pure water and ethanol, and then dried at 70°C for 48 hours.

[0170] Comparative Example 1

[0171] The difference from Example 1 is that step (3) of preparing nitrogen-doped graphene oxide is not performed, and the preparation process of step (8) of bipolar membrane is as follows:

[0172] Take a clean glass plate, pour the cation exchange membrane solution onto it, scrape the membrane with a 200μm scraper, heat it on a 70°C hotplate for 3 hours, and then immerse it in pure water until the membrane naturally falls off. This completes the cation exchange membrane. The cation exchange membrane is then affixed to the glass plate, and the anion exchange membrane solution is cast onto it. This bipolar membrane is then heated on a 50°C hotplate for 3 hours. This bipolar membrane does not contain an intermediate layer.

[0173] 2. Performance Testing

[0174] (1) Qualitative test: An X-ray photoelectron spectrometer model NEXSA from Thermo Fisher Scientific, USA, was used to qualitatively detect the elemental composition of the material. In this test, the elements contained in the nitrogen-doped graphene oxide prepared in Example 1 were determined. The results are shown in Figure 2. Figure 4 As shown. Figure 4 , it can be seen that nitrogen is successfully loaded onto graphene oxide.

[0175] (2) Quantitative testing: An elemental analyzer, model Varioo EI cube, manufactured by Elimonta, Germany, was used to analyze the percentage of C, H, N, and S elements contained in the material. In this test, the CHNS mode was used to determine the molar percentage of C, H, and N elements contained in the nitrogen-doped graphene oxide prepared in Example 1. The results are shown in Table 1.

[0176] Table 1 Molar percentage of elements in nitrogen-doped graphene oxide

[0177]

[0178] As shown in Table 1, the nitrogen-doped graphene oxide prepared in Example 1 has a N content of 4.02%, a C content of 54.58%, and a H content of 3.44%.

[0179] (3) Appearance morphology test: The cross section of the bipolar membrane prepared in Example 1 was observed using a scanning electron microscope (Gemini SEM500) from Carl Zeiss, Germany. The specific operation was as follows: the bipolar membrane was taken out of the deionized water, dried, and an appropriate amount of the membrane was cut and pasted on the conductive adhesive for gold spraying and observation. The results are shown in Figure 2. Figure 5 As shown by Figure 5 It can be seen that the prepared bipolar membrane has a clear three-layer structure with no delamination. The thickness of the cation exchange membrane layer is 80 μm, and the thickness of the anion exchange membrane layer is about 40 μm.

[0180] (4) Current-voltage curve test: A quadrupole chamber system membrane stack (+ proton exchange membrane | bipolar membrane | proton exchange membrane | -) was connected to an electrochemical workstation, and the Linear Sweep Voltammetry Galvanostatic program was selected to test the bipolar membranes of Comparative Example 1 and Example 1. 1 mol / L sodium sulfate solution was used in both the electrode chamber and the acid-base chamber. During the test, the current growth rate was 2 mA / s, and the current test range was 0-0.2 A. The results are shown in FIG. Figure 6 As shown in the figure, the transmembrane voltage of the bipolar membranes of Comparative Example 1 and Example 1 gradually increases with the increase of current. 2 When the transmembrane voltage of comparative example 1 is 2.18 V, the transmembrane voltage of embodiment 1 is 0.98 V, which proves that using nitrogen-doped graphene oxide as the intermediate catalytic layer can effectively reduce the voltage required for water dissociation.

[0181] (5) Stability test: A quadrupole system membrane stack (+ proton exchange membrane | bipolar membrane | proton exchange membrane | -) was connected to an electrochemical workstation, and the Chrono Potentiometry program was selected to test the bipolar membranes of Comparative Example 1 and Example 1. 1 mol / L sodium sulfate solution was used in both the electrode chamber and the acid-base chamber. During the test, the current was set to 50 mA / cm 2 The test duration is 10 hours and the time interval is 20 seconds. Figure 7 As shown in the graph, during the test process lasting up to 10 hours, the voltage required for water dissociation of the bipolar membrane of Example 1 is more stable than that of Comparative Example 1, indicating that the nitrogen-doped graphene oxide intermediate layer catalyst added in the present invention can effectively enhance the stability of the bipolar membrane, and the intermediate layer is tightly combined with the cation exchange membrane layer, avoiding the problem of increased water dissociation voltage caused by catalyst shedding.

[0182] (6) Acid and base performance test: The bipolar membranes of Comparative Example 1 and Example 1 were tested using a hexapole system membrane stack (+ anion exchange membrane | cation exchange membrane | bipolar membrane | anion exchange membrane | cation exchange membrane | -). 1 mol / L sodium sulfate solution was used in the electrode chamber, salt chamber, and acid and base chamber, and the current density was set to 50 mA / cm 2 The running time is 3 hours, and samples are taken every 30 minutes to determine the concentration of the acid-base chamber by acid-base titration. Figure 8 As shown, compared with Comparative Example 1, the acid-base chamber concentration of Example 1 is positively correlated with time and is almost linear, that is, the acid-base production rate does not change significantly during the 3-hour operation. 2 At a current density of , after 3 h, the acid and alkali concentration of Comparative Example 1 is about 0.08 mol / L, and the acid and alkali concentration of Example 1 can reach about 0.15 mol / L.

[0183] Based on all the above test results, it can be concluded that using nitrogen-doped graphene oxide as a catalyst in the middle layer of the bipolar membrane can significantly reduce the voltage required for water dissociation in the bipolar membrane, reduce energy consumption and improve acid and alkali production performance.

[0184] At the same current density (50mA / cm 2 ), the voltage required for water dissociation in Comparative Example 1 was 2.18 V, and the acid and base concentration produced was 0.08 mol / L; the voltage required for water dissociation in Example 1 was 0.98 V, and the acid and base concentration produced was 0.15 mol / L. Furthermore, during the 10-hour test, the voltage required for water dissociation in the bipolar membrane of Example 1 remained stable between 0.98 and 1.10 V, compared to Comparative Example 1.

[0185] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0186] The above-described embodiments merely represent several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the patent. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present invention, and these modifications and improvements fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be based on the appended claims, and the description and drawings shall be used to interpret the content of the claims.

Claims

1. A bipolar membrane, characterized in that It comprises a cation exchange membrane, an intermediate layer and an anion exchange membrane stacked in sequence, wherein the intermediate layer comprises nitrogen-doped graphene oxide; The loading amount of nitrogen-doped graphene oxide contained in the intermediate layer is 0.2 mg / cm 2 ~1.0mg / cm 2 ; The molar percentage of nitrogen in the nitrogen-doped graphene oxide contained in the intermediate layer is 4% to 5%; The particle size of the nitrogen-doped graphene oxide contained in the intermediate layer is less than or equal to 0.054 mm; The preparation method of the nitrogen-doped graphene oxide comprises the following steps: adding graphene oxide powder to ammonia water, stirring the resulting suspension, performing solid-liquid separation, washing, and drying to prepare nitrogen-doped graphene oxide having a particle size of less than or equal to 0.054 mm; The obtained suspension is stirred at 30°C to 75°C. The obtained suspension is subjected to a stirring step, wherein the stirring time is 4 h to 6 h; The obtained suspension is subjected to a stirring step, and the stirring speed is 200 rpm-400 rpm.

2. The bipolar membrane according to claim 1, characterized in that Meet one or more of the following characteristics: The cation exchange membrane comprises sulfonated polysulfone, and the sulfonated polysulfone has a sulfonation degree of 35% to 50%; The anion exchange membrane comprises quaternized polysulfone, and the quaternization degree of the quaternized polysulfone is 40% to 50%.

3. A method for preparing a bipolar membrane, characterized in that: The following steps are involved: The cation exchange membrane is prepared by forming a film of the cation exchange membrane liquid on the substrate using a casting method; loading nitrogen-doped graphene oxide onto the cation exchange membrane to form an intermediate layer comprising the nitrogen-doped graphene oxide on the cation exchange membrane; Casting an anion exchange membrane liquid onto the surface of the intermediate layer away from the cation exchange membrane, drying, and forming an anion exchange membrane on the surface of the intermediate layer away from the cation exchange membrane to prepare a bipolar membrane; The loading amount of nitrogen-doped graphene oxide contained in the intermediate layer is 0.2 mg / cm 2 ~1.0mg / cm 2 ; The molar percentage of nitrogen in the nitrogen-doped graphene oxide contained in the intermediate layer is 4% to 5%; The particle size of the nitrogen-doped graphene oxide contained in the intermediate layer is less than or equal to 0.054 mm; The preparation method of the nitrogen-doped graphene oxide comprises the following steps: adding graphene oxide powder to ammonia water, stirring the resulting suspension, performing solid-liquid separation, washing, and drying to prepare nitrogen-doped graphene oxide having a particle size of less than or equal to 0.054 mm; The obtained suspension is stirred at 30°C to 75°C. The obtained suspension is subjected to a stirring step, wherein the stirring time is 4 h to 6 h; The obtained suspension is subjected to a stirring step, and the stirring speed is 200 rpm-400 rpm.

4. The preparation method according to claim 3, characterized in that The cation exchange membrane liquid comprises sulfonated polysulfone and a first organic solvent; the anion exchange membrane liquid comprises quaternized polysulfone and a second organic solvent; The method for preparing the bipolar membrane satisfies one or more of the following characteristics: In the cation exchange membrane solution, the ratio of the sulfonated polysulfone to the first organic solvent is 10 g: (50-75) mL, based on the feed amount; In the anion exchange membrane solution, the ratio of the quaternized polysulfone to the second organic solvent is 10 g: (50-75) mL, based on the feed amount; The first organic solvent and the second organic solvent each independently comprise one or more of dimethylformamide, dimethylacetamide and N-methylpyrrolidone; The step of loading nitrogen-doped graphene oxide onto a cation exchange membrane comprises: mixing the nitrogen-doped graphene oxide with a third solvent to prepare an intermediate layer suspension, loading the intermediate layer suspension onto the cation exchange membrane, and performing a suction filtration process.

5. The preparation method according to claim 4, characterized in that The preparation method of the sulfonated polysulfone comprises the following steps: In the presence of a fourth organic solvent, the first polysulfone is subjected to a sulfonation reaction with sulfuric acid, followed by alcohol precipitation and drying to prepare the sulfonated polysulfone.

6. The preparation method according to claim 5, characterized in that The preparation method of the sulfonated polysulfone meets one or more of the following characteristics: Based on the feed amount, the ratio of the first polysulfone to the sulfuric acid is 10 g: (2-10) mL; Calculated by feed amount, the ratio of the first polysulfone to the fourth organic solvent is 10 g: (100-150) mL; The weight average molecular weight of the first polysulfone is 30 kDa to 40 kDa, and the number average molecular weight of the first polysulfone is 20 kDa to 30 kDa; The fourth organic solvent comprises one or more of dichloroethane, dichloromethane and chloroform.

7. The preparation method according to claim 4, characterized in that The preparation method of the quaternized polysulfone comprises the following steps: In the presence of a fifth organic solvent, the second polysulfone is reacted with chloromethyl ethyl ether and anhydrous tin tetrachloride, followed by alcohol precipitation and drying to prepare chloromethylated polysulfone; In the presence of a sixth organic solvent, the chloromethylated polysulfone is reacted with triethylamine, followed by alcohol precipitation and drying to prepare the quaternized polysulfone.

8. The preparation method according to claim 7, characterized in that The preparation method of the quaternized polysulfone satisfies one or more of the following characteristics: Based on the feeding amount, the ratio of the second polysulfone to the fifth organic solvent is 10 g: (100-150) mL; Based on the feed amount, the ratio of the second polysulfone to the chloromethyl ether is 10 g: (5-10) mL; Based on the feed amount, the ratio of the second polysulfone to the anhydrous tin tetrachloride is 10 g: (1-2) mL; Based on the amount of material added, the ratio of the chloromethylated polysulfone to the sixth organic solvent is 5 g: (100-200) mL; Based on the amount of material added, the ratio of the chloromethylated polysulfone to the triethylamine solution is 5 g: (5-10) mL; The weight average molecular weight of the second polysulfone is 30 kDa to 40 kDa, and the number average molecular weight of the second polysulfone is 20 kDa to 30 kDa; The fifth organic solvent comprises one or more of dichloroethane, dichloromethane and chloroform; The sixth organic solvent includes one or more of N-methylpyrrolidone, N,N-dimethylformamide, and N,N-dimethylacetamide.

9. The preparation method according to any one of claims 3 to 8, characterized in that The volume ratio of the cation exchange membrane liquid to the anion exchange membrane liquid is 2:(1~3).

10. Use of the bipolar membrane according to any one of claims 1 to 2 or the bipolar membrane prepared by the preparation method according to any one of claims 3 to 9 in water dissociation or in the preparation of an electrodialysis device.

11. An electrodialysis device, characterized in that: The invention relates to a bipolar membrane comprising the bipolar membrane according to any one of claims 1 to 2 or a bipolar membrane prepared by the preparation method according to any one of claims 3 to 9.

Images