Method for differentiating and characterizing negative membrane layer and positive membrane layer of bipolar membrane

Abstract

The invention discloses a method for differentially characterizing a negative membrane layer and a positive membrane layer of a bipolar membrane, which comprises the following steps: 1) enabling the positive membrane side of the bipolar membrane to be in contact with a first layered liquid, enabling the negative membrane side of the bipolar membrane to be in contact with a second layered liquid, separating the first layered liquid from the second layered liquid by the bipolar membrane, meanwhile, the bipolar membrane is stripped into an anode membrane and a cathode membrane under a forward electrifying condition; (2) alternately soaking the anion membrane layer and the cation membrane layer obtained in the step (1) with cleaning acid liquor and cleaning alkali liquor; and (3) respectively representing the selectivity of the positive membrane layer and the selectivity of the negative membrane layer which are treated in the step (2). According to the method, the selectivity of the negative membrane layer and the positive membrane layer of the bipolar membrane can be independently evaluated, the selectivity of the negative membrane layer and the positive membrane layer of the bipolar membrane can be respectively calculated, and basic data support is provided for research on different influences of the overall performance of the material and an internal reaction mechanism of the material; powerful support is provided for improvement of a bipolar membrane preparation process and verification of a structure.

Description

Technical Field

[0001] The invention relates to the technical field of bipolar membrane utilization, and in particular to a method for distinguishing and characterizing a cationic membrane layer and a cation membrane layer of a bipolar membrane. Background Art

[0002] Bipolar membrane electrodialysis (BMED) technology is a method of producing and separating acidic and alkaline solutions from mixed solutions through the action of an electric field. This technology has the advantages of simple operation, high efficiency, and no need to add any chemical reagents, and has attracted widespread attention in the field of acid and base preparation. The bipolar membrane is composed of a cationic membrane layer, a catalytic layer, and a cation membrane layer. It has the function of producing the following phenomenon called hydrolysis: by applying a voltage to both sides of the bipolar membrane immersed in an aqueous solution, the water in the membrane is dissociated into protons and hydroxide ions. Using this function, the bipolar membrane is combined with a cation exchange membrane and an anion exchange membrane to perform electrodialysis, for example, acids and bases can be produced from neutral salts.

[0003] Characterization of bipolar membranes has the following important significance: from the perspective of product application, characterization of bipolar membrane properties such as energy consumption and selectivity helps to select products according to the actual application requirements of the products; from the perspective of product development and production, characterization of the various properties of bipolar membranes helps to develop and produce high-performance products in a targeted manner.

[0004] The existing technology can only characterize the selectivity of bipolar membranes as a whole. For example, the mass transfer performance of bipolar membranes is characterized by the determination method of bipolar membrane current efficiency. There is no method to separately characterize the individual anion membrane layer and cation membrane layer, which has brought a major obstacle to the development of bipolar membranes. Summary of the invention

[0005] In order to solve the above-mentioned defects in the prior art, the present invention provides a method for distinguishing and characterizing the cationic membrane layer and the cation membrane layer of a bipolar membrane, which can evaluate the selectivity of the cationic membrane layer and the cation membrane layer of the bipolar membrane separately, and only requires tens of square centimeters of membrane sample to obtain sample information, which has the advantages of wide applicability / accuracy and high efficiency.

[0006] To achieve the above-mentioned object of the invention, the present invention provides a method for distinguishing and characterizing the cathodic membrane layer and the cation membrane layer of a bipolar membrane, comprising:

[0007] 1) contacting the anode side of the bipolar membrane with a first layered liquid, and contacting the cathode side of the bipolar membrane with a second layered liquid, the bipolar membrane separates the first layered liquid from the second layered liquid, and simultaneously peeling the bipolar membrane into an anode membrane and a cathode membrane under a forward power supply condition;

[0008] 2) alternately soaking the anion film layer and the cation film layer obtained in step 1) with a cleaning acid solution and a cleaning alkali solution;

[0009] 3) characterizing the selectivity of the positive membrane layer and the negative membrane layer obtained by the treatment in step 2);

[0010] Wherein, the first layered liquid is a mixed solution containing acid and metal ions, and the second layered liquid is an alkaline solution.

[0011] Furthermore, the first layered liquid is a mixed solution of an acid solution and an aqueous solution containing metal ions.

[0012] Furthermore, the acid solution is selected from one or more of dilute sulfuric acid, dilute hydrochloric acid, and dilute nitric acid; the metal ion is selected from Al 3+ Fe 3+ ,Cu 2+ Mg 2+ One or more of .

[0013] Furthermore, in the second layered liquid, the alkaline solution is selected from one or more of a sodium hydroxide aqueous solution, a potassium hydroxide aqueous solution, and a lithium hydroxide aqueous solution.

[0014] Furthermore, the concentration of the acid solution is 0.1N-0.5N, the concentration of the metal ion-containing aqueous solution is 0.1N-0.5N, and the concentration of the alkali solution is 0.3N-3N.

[0015] Furthermore, in step 1), the current density of the forward current is 400-1500A / m 2 , the power-on time is 15-120min.

[0016] Furthermore, in step 2), the concentration of the cleaning acid solution or the cleaning alkali solution is 1-5N; the alternating process is to first soak the membrane in the cleaning acid solution for 0.5-6h, then wash the membrane with pure water and then soak it in the cleaning alkali solution for 0.5-6h, and then wash the membrane with pure water after alternating for several times;

[0017] Preferably, the cleaning acid is selected from one or more of dilute sulfuric acid, dilute hydrochloric acid, and dilute nitric acid;

[0018] Preferably, the cleaning alkali solution is selected from one or more of a sodium hydroxide aqueous solution, a potassium hydroxide aqueous solution, and a lithium hydroxide aqueous solution.

[0019] Furthermore, in step 3), the selectivity of the cation layer is characterized by using a cation layer selectivity measuring device, and the characterization method includes: contacting one side of the cation layer with a first cation layer measuring liquid, and contacting the other side with a second cation layer measuring liquid, the cation layer separates the first cation layer measuring liquid and the second cation layer measuring liquid, and performing the characterization test under power-on conditions.

[0020] Furthermore, the first cation layer measuring solution and the second cation layer measuring solution are alkaline solutions with different concentrations.

[0021] Furthermore, the first cation layer measuring liquid is one or more of a 2-6N sodium hydroxide aqueous solution, a potassium hydroxide aqueous solution, and a lithium hydroxide aqueous solution, and the second cation layer measuring liquid is one or more of a 0-0.1N sodium hydroxide aqueous solution, a potassium hydroxide aqueous solution, and a lithium hydroxide aqueous solution.

[0022] Furthermore, in step 3), the selectivity of the negative membrane layer is characterized by using a negative membrane layer selectivity measurement device, and the characterization method includes: contacting one side of the negative membrane layer with a first negative membrane layer measurement liquid, and contacting the other side with a second negative membrane layer measurement liquid, the negative membrane layer separates the first negative membrane layer measurement liquid and the second negative membrane layer measurement liquid, and performing the characterization test under power-on conditions.

[0023] Furthermore, the first anion film layer measuring liquid and the second anion film layer measuring liquid are acid solutions with different concentrations.

[0024] Furthermore, the first anion layer measuring liquid is one or more of 0-0.1N dilute sulfuric acid, dilute hydrochloric acid, and dilute nitric acid; the second anion layer measuring liquid is one or more of 1-5N dilute sulfuric acid, dilute hydrochloric acid, and dilute nitric acid.

[0025] Furthermore, the current density of the energization is 400-1500A / m 2 , the power-on time is 8-30h.

[0026] Further, in step 3), in the characterization test, the selective permeability of the cathode membrane or the anode membrane is characterized by the selectivity coefficient shown in the following formula:

[0027]

[0028] Where A is the selection coefficient

[0029] C0 is dilute acid H + Or dilute alkali OH - Initial concentration, mol / L

[0030] C t For dilute acid H + Or dilute alkali OH - End concentration, mol / L

[0031] V is the volume of dilute acid or dilute alkali solution, mL

[0032] I is the current, A

[0033] t is the power-on time, s

[0034] F is Faraday constant, 96485C / mol.

[0035] The beneficial effects of the present invention are as follows:

[0036] The present invention provides a method for distinguishing and characterizing the anion membrane layer and the cation membrane layer of a bipolar membrane. First, the bipolar membrane is stripped into the anode membrane and the cathode membrane using the first layering liquid and the second layering liquid under the condition of positive power supply; then, the anion membrane layer and the cation membrane layer are alternately soaked with a cleaning acid solution and a cleaning alkali solution to remove the catalytic layer remaining on the surface; finally, the selectivity of the cation membrane layer and the anion membrane layer obtained by the treatment is characterized respectively. Therefore, the method of the present invention can evaluate the selectivity of the anion membrane layer and the cation membrane layer of the bipolar membrane separately. The selectivity directly affects the performance of the membrane such as the current efficiency and the unit processing capacity. The present invention can calculate the selectivity of the anion membrane layer and the cation membrane layer of the bipolar membrane separately, provide basic data support for the study of the different effects on the overall performance of the material and the internal reaction mechanism of the material, and provide strong support for the improvement of the bipolar membrane preparation process and the verification of the structure.

[0037] Other features and advantages of the present invention will be described in detail through the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 A schematic diagram of the structure of a bipolar membrane layering device provided in an embodiment of the present invention.

[0039] Figure 2 Schematic diagram of a cathode film layer selectivity testing device provided in an embodiment of the present invention.

[0040] Figure 3 Schematic diagram of a cation film layer selectivity testing device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0041] The following will clearly and completely describe the concept of the present application and the technical effects produced in combination with the embodiments, so as to fully understand the purpose, features and effects of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of them. Based on the embodiments of the present application, other embodiments obtained by those skilled in the art without creative work are all within the scope of protection of the present application.

[0042] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limitations on the present invention.

[0043] The present invention provides a method for distinguishing and characterizing a cationic membrane layer and a cation membrane layer of a bipolar membrane, comprising:

[0044] 1) contacting the anode side of the bipolar membrane with a first layered liquid, and contacting the cathode side of the bipolar membrane with a second layered liquid, the bipolar membrane separates the first layered liquid from the second layered liquid, and simultaneously peeling the bipolar membrane into an anode membrane and a cathode membrane under a forward power supply condition;

[0045] 2) alternately soaking the anion film layer and the cation film layer obtained in step 1) with a cleaning acid solution and a cleaning alkali solution;

[0046] 3) characterizing the selectivity of the positive membrane layer and the negative membrane layer obtained by the treatment in step 2);

[0047] The first layering liquid is a mixed solution containing acid and iron ions, and the second layering liquid is an alkaline solution. The purpose of such arrangement is to generate heat and water between the cation and cathode membrane layers and to generate new substances that promote membrane separation.

[0048] In some specific embodiments, in step 1), a layered device is used for bipolar membrane separation, for example, Figure 1 As shown, the interior of the stratification device is used to accommodate the first stratification liquid and the second stratification liquid, and the bipolar membrane is placed inside the device to separate the first stratification liquid and the second stratification liquid. Specifically, the bipolar membrane can be placed inside the device first, and then the first stratification liquid and the second stratification liquid are added to both sides of the bipolar membrane respectively.

[0049] In some specific embodiments, the first layered liquid is a mixed solution of an acid solution and an aqueous solution containing metal ions.

[0050] For example, in the first layered liquid, the acid solution is selected from one or more of dilute sulfuric acid, dilute hydrochloric acid, and dilute nitric acid; the metal ion is selected from Al 3+ Fe 3+ ,Cu 2+ Mg 2+ One or more of .

[0051] Illustratively, in the second layered liquid, the alkaline solution is selected from one or more of a sodium hydroxide aqueous solution, a potassium hydroxide aqueous solution, and a lithium hydroxide aqueous solution.

[0052] In some specific embodiments, the concentration of the acid solution is 0.1N-0.5N, the concentration of the aqueous solution containing metal ions is 0.1N-0.5N, and the concentration of the alkali solution is 0.3N-3N. The purpose of setting the concentration as above is to separate the membrane layers by bubbling without destroying the membrane structure.

[0053] In some specific embodiments, in step 1), the current density of the forward current is 400-1500 A / m 2 The purpose of this setting is to separate the bubbles between the membrane layers without destroying the membrane structure.

[0054] In some specific embodiments, in step 2), the negative membrane layer and the positive membrane layer obtained in step 1) are alternately soaked with a cleaning acid solution and a cleaning alkali solution. The negative membrane layer and the positive membrane layer can be placed in the same container and soaked together, or the negative membrane layer and the positive membrane layer can be soaked separately. The purpose of soaking is to remove the catalyst that may exist on the surface of the membrane layer.

[0055] In some specific embodiments, in step 2), the concentration of the cleaning acid solution or the cleaning alkali solution is 1-5N; the alternating process is to first soak the membrane in the cleaning acid solution for 0.5-6h, then wash the membrane with pure water and then soak it in the cleaning alkali solution for 0.5-6h, and then wash the membrane with pure water after alternating for multiple times, for example, three times;

[0056] Preferably, the cleaning acid is selected from one or more of dilute sulfuric acid, dilute hydrochloric acid, and dilute nitric acid;

[0057] Preferably, the cleaning alkali solution is selected from one or more of a sodium hydroxide aqueous solution, a potassium hydroxide aqueous solution, and a lithium hydroxide aqueous solution.

[0058] In some specific embodiments, in step 3), the selectivity of the cation layer is characterized by using a cation layer selectivity determination device, and the characterization method includes: contacting one side of the cation layer with a first cation layer determination liquid, and contacting the other side with a second cation layer determination liquid, the cation layer separates the first cation layer determination liquid and the second cation layer determination liquid, and performing a characterization test under power-on conditions. For example, referring to Figure 2 As shown, the interior of the cation layer selectivity measurement device is used to contain the first cation layer measurement liquid and the second cation layer measurement liquid, and the anode membrane is placed inside the device to separate the first cation layer measurement liquid and the second cation layer measurement liquid. Specifically, the anode membrane can be placed inside the device first, and then the first cation layer measurement liquid and the second cation layer measurement liquid are added to both sides of the anode membrane.

[0059] In some specific embodiments, the first cation layer test solution and the second cation layer test solution are alkaline solutions with different concentrations. The purpose of such a setting is to simulate the state of the cation layer in actual application to more accurately characterize the selectivity of the cation layer.

[0060] In some specific embodiments, the first cation layer measuring liquid is one or more of a 2-6N dilute sodium hydroxide aqueous solution, a potassium hydroxide aqueous solution, and a lithium hydroxide aqueous solution, and the second cation layer measuring liquid is one or more of a 0-0.1N dilute sodium hydroxide aqueous solution, a potassium hydroxide aqueous solution, and a lithium hydroxide aqueous solution, and their concentrations can be infinitely small.

[0061] In some specific embodiments, in step 3), the selectivity of the negative membrane layer is characterized by using a negative membrane layer selectivity determination device, and the characterization method includes: contacting one side of the negative membrane layer with a first negative membrane layer determination liquid, and contacting the other side with a second negative membrane layer determination liquid, the negative membrane layer separates the first negative membrane layer determination liquid and the second negative membrane layer determination liquid, and performing a characterization test under power-on conditions. Exemplarily, for example, referring to Figure 3 As shown, the interior of the negative membrane layer selective measurement device is used to contain the first negative membrane layer measurement liquid and the second negative membrane layer measurement liquid, and the cathode membrane is placed inside the device to separate the first negative membrane layer measurement liquid and the second negative membrane layer measurement liquid. Specifically, the cathode membrane can be placed inside the device first, and then the first negative membrane layer measurement liquid and the second negative membrane layer measurement liquid are added to both sides of the cathode membrane.

[0062] In some specific embodiments, the first anion membrane layer measuring solution and the second anion membrane layer measuring solution are acid solutions with different concentrations. The purpose of such a setting is to simulate the state of the anion membrane layer in actual application to more accurately characterize the selectivity of the anion membrane layer.

[0063] In some specific embodiments, the first anion layer assay liquid is one or more of 0-0.1N dilute sulfuric acid, dilute hydrochloric acid, and dilute nitric acid, and its concentration can be infinitely small; the second anion layer assay liquid is one or more of 1-5N dilute sulfuric acid, dilute hydrochloric acid, and dilute nitric acid.

[0064] In some specific embodiments, in the characterization method, the current density of the current is 400-1500A / m 2 The purpose of this setting is to simulate the state of the membrane layer in actual application, visualize the gap between products, and accurately characterize the selectivity of the membrane layer.

[0065] In some specific embodiments, in step 3), in the characterization test, the cathode film or the anode film is characterized by the selectivity coefficient shown in the following formula:

[0066]

[0067] Where A is the selection coefficient

[0068] C0 is dilute acid H + Or dilute alkali OH - Initial concentration, mol / L

[0069] C t For dilute acid H + Or dilute alkali OH - End concentration, mol / L

[0070] V is the volume of dilute acid or dilute alkali solution, mL

[0071] I is the current, A

[0072] t is the power-on time, s

[0073] F is Faraday constant, 96485C / mol.

[0074] In the present invention, the above selectivity coefficient can be used to characterize the selective permeability of each membrane layer of the bipolar membrane to hydrogen ions and hydroxide ions.

[0075] The present invention is further illustrated below with examples, but the present invention is not limited thereto.

[0076] Example 1: Take a commercially available bipolar membrane 1, take samples of 4*7cm (effective area 2*5cm), and place them Figure 1 In the layering device shown, 100 mL of a mixed solution of 0.2 N dilute sulfuric acid and 0.3 N ferric chloride aqueous solution in equal proportions was used as layering liquid 1, and 100 mL of a 0.5 N dilute sodium hydroxide solution was used as layering liquid 2. Electric current was applied at a constant current of 1 A for 1 h to obtain a bipolar membrane with a completely separated cathodic membrane layer and a cation membrane layer.

[0077] Comparative Example 1: Using a 2-chamber unit having the following structure, at a liquid temperature of 25°C and a current density of 30 A / dm 2 When the power was turned on for 5 hours under the condition of , dense bubbles appeared on the bipolar membrane. This may be because there were only water and heat production processes, and the anion membrane layer and the cation membrane layer could not be completely separated.

[0078] Cathode (Pt plate) (1.0 mol / L-NaOH) / determination bipolar membrane / (1.0 mol / L-HCl) Anode (Pt plate)

[0079] Comparative Example 2: Take commercially available bipolar membrane 1, take samples of 4*7cm (effective area 2*5cm), and place them Figure 1 In the stratification device shown, 100 mL of a mixed solution of 0.2 N dilute sulfuric acid and 0.3 N ferric chloride aqueous solution in equal proportions was used as stratification liquid 1, and 100 mL of a 0.5 N dilute sodium hydroxide solution was used as stratification liquid 2. Electric current was passed at a constant current of 0.1 A for 1 h. The current density was too small, small bubbles formed on the bipolar membrane, and the anionic membrane layer and the cation membrane layer could not be completely separated.

[0080] By comparing the above Example 1 with Comparative Examples 1 and 2, it can be seen that the positive and negative membrane layers of the bipolar membrane can be completely peeled off by the method of the present application.

[0081] Example 2: Take the anion membrane layer and the cation membrane layer separated in Example 1, soak them in 2N HCl for 3 hours, wash them with pure water, soak them in 2N NaOH for 3 hours, wash them with pure water, repeat this three times, and then place the anion membrane layer in Figure 3 In the anion film layer selectivity test device shown in FIG. 1 , the selectivity coefficient was measured to be 0.95. The anion film layer was placed Figure 2In the cation layer selectivity test device shown, the selectivity coefficient was measured to be 0.86. The first anion layer test solution and the second anion layer test solution were 0.01N and 3N dilute hydrochloric acid, respectively. The first anion layer test solution and the second anion layer test solution were 0.001N and 3.5N dilute NaOH solutions, respectively. The power-on parameters of the anion layer selectivity test device and the cation layer selectivity test device respectively include: constant current 0.8A, power-on time 30h.

[0082]

[0083] In this embodiment, the specific values ​​of the above parameters are that I is 0.8, t is 1.08*10 5 , F is 96485, V is 0.1, positive film layer c o is 3.498, c t is 3.051, the anterior membrane layer c o is 3.012, c t is 1.762, and the above selectivity coefficient is obtained by calculation.

[0084] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as limiting the present invention. Those skilled in the art will appreciate that, under the guidance of this specification, some modifications or adjustments may be made to the present invention. These modifications or adjustments should also be within the scope defined by the claims of the present invention.

Claims

1. A method for distinguishing and characterizing the anionic membrane layer and the cation membrane layer of a bipolar membrane, characterized in that: include: 1) contacting the anode side of the bipolar membrane with a first layered liquid, and contacting the cathode side of the bipolar membrane with a second layered liquid, the bipolar membrane separates the first layered liquid from the second layered liquid, and simultaneously peeling the bipolar membrane into an anode membrane and a cathode membrane under a forward power supply condition; 2) alternately soaking the anion film layer and the cation film layer obtained in step 1) with a cleaning acid solution and a cleaning alkali solution; 3) characterizing the selectivity of the cation membrane layer and the selectivity of the anion membrane layer obtained by the treatment in step 2); Wherein, the first layered liquid is a mixed solution containing acid and metal ions, and the second layered liquid is an alkaline solution.

2. The method for distinguishing and characterizing the anion layer and the cation layer of a bipolar membrane according to claim 1, characterized in that: The first layered liquid is a mixed solution of an acid solution and an aqueous solution containing metal ions; Preferably, in the first layered liquid, the acid solution is selected from one or more of dilute sulfuric acid, dilute hydrochloric acid, and dilute nitric acid; the metal ion is selected from Al 3+ Fe 3+ ,Cu 2+ Mg 2+ One or more of; Preferably, in the second layered liquid, the alkali solution is selected from one or more of a sodium hydroxide aqueous solution, a potassium hydroxide aqueous solution, and a lithium hydroxide aqueous solution; Preferably, the concentration of the acid solution is 0.1N-0.5N, the concentration of the metal ion-containing aqueous solution is 0.1N-0.5N, and the concentration of the alkali solution is 0.3N-3N.

3. The method for distinguishing and characterizing the anion layer and the cation layer of a bipolar membrane according to claim 1 or 2, characterized in that: In step 1), the current density of the energized current is 400-1500A / m 2 , the power-on time is 15-120min.

4. The method for distinguishing and characterizing the anionic membrane layer and the cation membrane layer of a bipolar membrane according to any one of claims 1 to 3, characterized in that: In step 2), the concentration of the cleaning acid solution or the cleaning alkali solution is 1-5N; the alternating process is to first soak the membrane in the cleaning acid solution for 0.5-6h, then wash the membrane with pure water and then soak it in the cleaning alkali solution for 0.5-6h, and then wash the membrane with pure water after alternating for several times; Preferably, the cleaning acid is selected from one or more of dilute sulfuric acid, dilute hydrochloric acid, and dilute nitric acid; Preferably, the cleaning alkali solution is selected from one or more of a sodium hydroxide aqueous solution, a potassium hydroxide aqueous solution, and a lithium hydroxide aqueous solution.

5. The method for distinguishing and characterizing the cationic membrane layer and the cation membrane layer of a bipolar membrane according to any one of claims 1 to 4, characterized in that: In step 3), the selectivity of the cation layer is characterized by using a cation layer selectivity measuring device, and the characterization method includes: contacting one side of the cation layer with a first cation layer measuring liquid, and contacting the other side with a second cation layer measuring liquid, the cation layer separates the first cation layer measuring liquid and the second cation layer measuring liquid, and performing the characterization test under power-on conditions.

6. The method for distinguishing and characterizing the anionic membrane layer and the cation membrane layer of a bipolar membrane according to claim 5, characterized in that: The first cation layer measuring solution and the second cation layer measuring solution are alkaline solutions with different concentrations; Preferably, the first cation layer measuring liquid is one or more of 2-6N sodium hydroxide aqueous solution, potassium hydroxide aqueous solution, and lithium hydroxide aqueous solution, and the second cation layer measuring liquid is one or more of 0-0.1N sodium hydroxide aqueous solution, potassium hydroxide aqueous solution, and lithium hydroxide aqueous solution.

7. The method for distinguishing and characterizing the cationic membrane layer and the cation membrane layer of a bipolar membrane according to any one of claims 1 to 4, characterized in that: In step 3), the selectivity of the negative membrane layer is characterized by using a negative membrane layer selectivity measurement device, and the characterization method includes: contacting one side of the negative membrane layer with a first negative membrane layer measurement liquid, and contacting the other side with a second negative membrane layer measurement liquid, the negative membrane layer separates the first negative membrane layer measurement liquid and the second negative membrane layer measurement liquid, and performing the characterization test under power-on conditions.

8. The method for distinguishing and characterizing the anionic membrane layer and the cation membrane layer of a bipolar membrane according to claim 7, characterized in that: The first anion film layer measuring solution and the second anion film layer measuring solution are acid solutions with different concentrations; Preferably, the first anion layer measuring solution is one or more of 0-0.1N dilute sulfuric acid, dilute hydrochloric acid, and dilute nitric acid, and the second anion layer measuring solution is one or more of 1-5N dilute sulfuric acid, dilute hydrochloric acid, and dilute nitric acid.

9. The method for distinguishing and characterizing the anionic membrane layer and the cation membrane layer of a bipolar membrane according to claim 5 or 7, characterized in that: The current density of the energization is 400-1500A / m 2 , the power-on time is 8-30h.

10. The method for distinguishing and characterizing the cationic membrane layer and the cation membrane layer of a bipolar membrane according to any one of claims 5 to 9, characterized in that: In step 3), in the characterization test, the selective permeability of the cathode membrane or the anode membrane is characterized by the selectivity coefficient shown in the following formula: Where A is the selection coefficient C0 is dilute acid H + Or dilute alkali OH - Initial concentration, mol / L C t For dilute acid H + Or dilute alkali OH - End concentration, mol / L V is the volume of dilute acid or dilute alkali solution, mL I is the current, A t is the power-on time, s F is Faraday constant, 96485C / mol.

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