Method for producing acid and alkali, and bipolar membrane electrodialysis device

Abstract

The present invention addresses the problem of providing, with respect to a method for producing an acid and an alkali using a bipolar membrane electrodialysis device: a method for producing an acid and an alkali with which it is possible to reduce the alkali production base unit; a bipolar membrane electrodialysis device; and a method for operating a bipolar membrane electrodialysis device. The solution to the foregoing is a method for producing an acid and an alkali, the method comprising supplying salt water to a bipolar membrane electrodialysis device comprising, as ion exchange membranes, a bipolar membrane, a cation exchange membrane, and an anion exchange membrane to perform electrodialysis to generate an acid and an alkali, wherein the hydrogen ion permeation flux of the anion exchange membrane is 7 × 10-8 mol m-2 s-1 or more for hydrochloric acid or 150 × 10-8 mol m -2 s-1 or more for sulfuric acid.

Description

Acid and alkali production method and bipolar membrane electrodialysis device

[0001] The present invention relates to a method for producing an acid and an alkali using a bipolar membrane electrodialysis device, a bipolar membrane electrodialysis device, an anion exchange membrane, and a method for operating a bipolar membrane electrodialysis device.

[0002] CO as a measure against global warming ２ In this context, as shown in Figure 1, calcium can be efficiently extracted from calcium-containing waste using an acid solution obtained by acid / alkali regeneration using bipolar membrane electrodialysis, and CO contained in exhaust gases can be efficiently removed using an alkaline solution. ２ By reacting the two, CO ２ It has been proposed to develop a carbon recycling process that saves energy and resources by immobilizing minerals.

[0003] In the carbon recycling process shown in FIG. 1 , the bipolar membrane electrodialysis device (BMED) uses a bipolar membrane, an anion exchange membrane (AEM), and a cation exchange membrane (CEM), and these three types of membranes are arranged between an anode and a cathode to form three compartments: an acid compartment, a raw material compartment (brine compartment), and an alkaline compartment. An aqueous salt solution (brine) is supplied to the raw material compartment, and by passing an electric current through the compartment, electrodialysis of the supplied salt is carried out, producing an acid and an alkali in the acid compartment and the alkaline compartment, respectively. The inventors discovered that in this electrodialysis, hydrogen ions (H ＋ ) leaks, which causes a decrease in the acid current efficiency and alkaline current efficiency. ＋ Low permeability and low H ＋ Using a permeable AEM, SO was used as the salt in the brine. ４ ２－ Cl, which is more likely to permeate AEM than ions (higher ion mobility). － By using NaCl to generate ions, H ＋Non-Patent Document 1 reports that the leakage of acid and alkali can be prevented and the current efficiency of the acid and alkali can be increased. However, further improvement in production efficiency has been required, and there has been a demand for a lower alkali production consumption rate. There has also been a demand for a lower acid production consumption rate.

[0004] "2020-2021 Achievement Report: Carbon Recycling and Next-Generation Thermal Power Generation Technology Development / Next-Generation Thermal Power Generation Technology Promotion Project / Development of Common Fundamental Technology for Carbon Recycling Technology / Research and Development of Calcium Extraction from Calcium-Containing Waste and CO2 Mineral Fixation Technology" (published in the New Energy and Industrial Technology Development Organization's Achievement Report Database on June 24, 2022)

[0005] An object of the present invention is to provide a method for producing an acid or alkali using a bipolar membrane electrodialysis apparatus, which can reduce the alkali production consumption rate or the acid production consumption rate, a bipolar membrane electrodialysis apparatus, and a method for operating a bipolar membrane electrodialysis apparatus.

[0006] The present inventors have been studying the method for producing acid and alkali from brine using a bipolar membrane electrodialysis device in order to improve production efficiency, and have focused on the alkali production unit. ＋ Since leakage (transmission amount) of H reduces the current efficiency, ＋ AEM with less leakage has been developed and used. ＋ Not only does this result in a low permeation rate for H, but the permeability of other ions also decreases, resulting in an increase in cell voltage, which in turn leads to an increase in the production unit, making it difficult to reduce the production unit. ＋ When the use of AEM, which has a high permeability of H, was investigated, it was found that the alkali production unit could be reduced. ＋ The amount of hydrogen ions (H ＋The inventors have found that the alkali production consumption rate can be optimized by using an anion exchange membrane having a specific hydrogen ion permeation flux that is determined based on the type of salt in the brine supplied and the alkali concentration of the alkaline aqueous solution produced. Furthermore, the inventors have found that the alkali production consumption rate can be optimized, as well as the acid production consumption rate, by using an anion exchange membrane having a specific hydrogen ion permeation flux that is determined based on the type of salt in the brine supplied and the acid concentration of the acid aqueous solution produced. This is how the present invention was completed.

[0007] That is, the present invention is characterized by the following features: (1) A method for producing an acid and an alkali by supplying brine to a bipolar membrane electrodialysis device equipped with a bipolar membrane, a cation exchange membrane, and an anion exchange membrane as ion exchange membranes, and performing electrodialysis to produce an acid and an alkali, wherein the hydrogen ion permeation flux of the anion exchange membrane is 7×10 for hydrochloric acid. －８ mol m －２ s －１ or above or 150 x 10 for sulfuric acid －８ molm －２ s －１ (2) A bipolar membrane electrodialysis device having a bipolar membrane, a cation exchange membrane, and an anion exchange membrane as ion exchange membranes, wherein the anion exchange membrane, an acid chamber in which an acid is produced, the bipolar membrane, an alkali chamber in which an alkali is produced, the cation exchange membrane, and a brine chamber to which brine is supplied are defined as one unit, and an ion exchange section is configured by arranging a plurality of such units, and the anion exchange membrane has a solubility of 7 × 10 with respect to hydrochloric acid. －８ mol m －２ s －１ or above or 150 x 10 for sulfuric acid －８ mol m －２ s －１(3) A bipolar membrane electrodialysis device having a bipolar membrane, a cation exchange membrane, and an anion exchange membrane as ion exchange membranes, wherein the anion exchange membrane, an acid chamber where an acid is produced, the bipolar membrane, an alkali chamber where an alkali is produced, the cation exchange membrane, and a brine chamber to which brine is supplied are formed as one unit, and a plurality of such units are arranged to form an ion exchange section, and the bipolar membrane electrodialysis device is used for the bipolar membrane electrodialysis device having an anion exchange membrane with a hydrogen ion permeation flux of 7 x 10 for hydrochloric acid. －８ mol m －２ s －１ or above or 150 x 10 for sulfuric acid －８ mol m －２ s －１ (4) A method for operating a bipolar membrane electrodialysis apparatus in which brine is supplied to the bipolar membrane electrodialysis apparatus provided with a bipolar membrane, a cation exchange membrane, and an anion exchange membrane as ion exchange membranes to produce an acid and an alkali, wherein the anion exchange membrane to be used is selected based on the hydrogen ion flux of the anion exchange membrane for hydrochloric acid or the hydrogen ion flux of the anion exchange membrane for sulfuric acid, depending on the type of salt in the brine to be supplied and / or the alkali concentration during operation. (5) In the case of selecting based on the hydrogen ion flux for hydrochloric acid, a method for operating a bipolar membrane electrodialysis apparatus in which the hydrogen ion flux is 7×10 or more, －８ mol m －２ s －１ The above anion exchange membrane and 7 × 10 －８ mol m －２ s －１ When selecting an anion exchange membrane to be used based on the hydrogen ion permeation flux for sulfuric acid, the anion exchange membrane having a hydrogen ion permeation flux of 150×10 －８ mol m －２ s －１ Anion exchange membrane and 150 x 10 －８ mol m －２ s －１(6) The method for operating the bipolar membrane electrodialysis apparatus according to (4) or (5), wherein the brine produced by a carbon recycling process using the bipolar membrane electrodialysis apparatus according to the operating method of (4) or (5) is used as the brine to be supplied to the bipolar membrane electrodialysis apparatus.

[0008] The method for producing an acid and an alkali, the bipolar membrane electrodialysis apparatus, and the method for operating the bipolar membrane electrodialysis apparatus of the present invention can reduce the alkali production consumption rate or the acid production consumption rate, or the alkali production consumption rate and the acid production consumption rate, in the production of an acid and an alkali using the bipolar membrane electrodialysis apparatus.

[0009] Fig. 1 is a diagram illustrating a carbon recycling process to which the present invention is applied. Fig. 2 is a schematic diagram of a bipolar membrane electrodialysis device. Fig. 3 is a diagram illustrating a H ＋ 4(a) is a diagram of an electrodialysis apparatus for measuring the permeation flux of J Ｗ and J Ｓ FIG. 4( a ) shows the measurement device and calculation formula for ( a ) and FIG. 4( b ) shows the measurement device and measurement conditions for membrane resistance. FIG. 4( c ) shows the measurement device for cation transport number. FIG. 5 shows the device conditions (a) and experimental conditions (b) used in the Examples and Reference Examples. FIG. 6 shows the relationship between alkali production and cell voltage in the Examples and Reference Examples. FIG. 7 shows the relationship between alkali production and cell voltage in the Examples and Reference Examples. FIG. 8 shows the relationship between alkali production and current efficiency in the Examples and Reference Examples. FIG. 9 shows the relationship between alkali production and current efficiency in the Examples and Reference Examples. FIG. 10 shows the relationship between alkali production and alkali production unit consumption in the Examples and Reference Examples. FIG. 11 shows the relationship between alkali production and alkali production unit consumption in the Examples and Reference Examples. FIG. 12 shows the relationship between acid production and acid production unit consumption in the Examples and Reference Examples.

[0010] The method for producing an acid and an alkali of the present invention is a method for producing an acid and an alkali by supplying brine to a bipolar membrane electrodialysis device equipped with a bipolar membrane, a cation exchange membrane, and an anion exchange membrane as ion exchange membranes, and performing electrodialysis to produce an acid and an alkali, wherein the hydrogen ion permeation flux of the anion exchange membrane is 7×10 －８ mol m －２ s －１ or above or 150 x 10 for sulfuric acid －８ mol m －２ s －１ This is the method for producing an acid and an alkali as described above. A bipolar membrane is an ion exchange membrane having a structure in which an anion exchange layer and a cation exchange layer are bonded together, and the bipolar membrane in the present invention is not particularly limited as long as it is an ion exchange membrane having such a structure. Examples of commercially available membranes include Neosepta (registered trademark) BM-1 (manufactured by Astom Corporation), Neosepta BPU (manufactured by Astom Corporation), and Fumasep FBM (manufactured by FuMA-Tech). In the present invention, the reaction of hydrogen ions (H ＋ ) The permeation flux is the permeation flux of an anion exchange membrane with an effective membrane area of ​​8 cm ２ The hydrogen ion permeation flux in electrodialysis measured in an atmosphere at 25°C by applying a constant current of 0.1 A in an electrodialysis apparatus sandwiched between a 0.5 M HCl aqueous solution and a 1 M NaCl aqueous solution is 7 × 10 hydrogen ion permeation flux in an anion exchange membrane when the hydrogen ion permeation flux ... －８ mol m －２ s －１ The hydrogen ion permeation flux measured above is 7×10 －８ mol m －２ s －１or more. Here, the effective membrane area is the membrane area through which ions actually permeate, and the same applies hereinafter. In the above measurement, an aqueous NaCl solution is placed as a salt solution on the negative electrode side of the anion exchange membrane to be measured, and an aqueous HCl solution is placed as an acid solution on the positive electrode side, and the hydrogen ion permeation flux is measured by observing the change in pH over time on the salt solution side. A specific method for measuring the hydrogen ion permeation flux is as described in the Examples. Hereinafter, unless otherwise specified, "hydrogen ion permeation flux through an anion exchange membrane for hydrochloric acid" means the hydrogen ion permeation flow rate under the above measurement conditions. In addition, in the present invention, the hydrogen ion permeation flux (H ＋ ) The permeation flux is the permeation flux of an anion exchange membrane with an effective membrane area of ​​8 cm ２ As a result, 0.5MH ２ SO ４ aqueous solution and 1M Na ２ SO ４ The hydrogen ion permeation flux in electrodialysis when a constant current of 0.1 A is applied and measured in an atmosphere of 25°C in an electrodialysis apparatus sandwiched between an anion exchange membrane and an aqueous solution, and the hydrogen ion permeation flux of the anion exchange membrane is 150 x 10 for sulfuric acid. －８ mol m －２ s －１ The hydrogen ion permeation flux measured above is 150×10 －８ mol m －２ s －１ In the above measurement, Na is used as a salt solution on the negative electrode side of the anion exchange membrane to be measured. ２ SO ４ Put the aqueous solution in the positive electrode and use H as an acid solution. ２ SO ４The hydrogen ion permeation flux is measured by pouring an aqueous solution into the anion exchange membrane and observing the change in pH over time on the salt solution side. A specific method for measuring the hydrogen ion permeation flux in the present invention is as described in the Examples. Hereinafter, unless otherwise specified, "hydrogen ion permeation flux of the anion exchange membrane with respect to sulfuric acid" refers to the hydrogen ion permeation rate under the above measurement conditions. In the present specification, mol / L may also be expressed as M. In the present invention, the hydrogen ion permeation flux of the anion exchange membrane may satisfy either the value with respect to hydrochloric acid or the value with respect to sulfuric acid, or may satisfy both. The anion exchange membrane of the present invention is not particularly limited as long as it is an anion exchange membrane that satisfies the above hydrogen ion permeation flux.

[0011] The cation exchange membrane in the present invention is not particularly limited as long as it can selectively permeate cations relative to anions. For example, the membrane resistance is 0.1 to 10 Ωcm. ２ (measured at a water temperature of 25°C and 0.5M NaCl) and a cation transference number of 0.90 to 0.99 (measured at a water temperature of 25°C and 0.5M NaCl). Examples of cation exchange membranes include commercially available membranes such as Neosepta CSE (manufactured by Astom Corporation) and SELEMION (registered trademark) CMVN (manufactured by AGC Engineering Co., Ltd.). The salt water in the present invention refers to an aqueous solution of salt, and examples of the salt include chlorides, nitrates, sulfates, carbonates, and phosphates of alkali metals. Specific examples include NaCl, KCl, LiCl, NaNO ３ , KNO ３ , LiNO ３ , Na ２ SO ４ , K. ２ SO ４ , Li ２ SO ４ , Na ２ CO ３ , K. ２ CO ３ , Na ３ P.O. ４ , K. ３ P.O. ４ In the present invention, when a salt of a monovalent acid such as NaCl is used as the salt of the brine, or when Na ２SO ４ In either case where a salt of a divalent or higher acid such as HCl or HCl is used, it is sufficient that the hydrogen ion flux for hydrochloric acid or the hydrogen ion flux for sulfuric acid is satisfied. However, when a salt of a monovalent acid is used, the hydrogen ion flux for hydrochloric acid may be used as a criterion for selecting an anion exchange membrane, and when a salt of a divalent or higher acid is used, the hydrogen ion flux for sulfuric acid may be used as a criterion for selecting an anion exchange membrane. The hydrogen ion flux for the anion exchange membrane in the present invention is 10×10 for hydrochloric acid. －８ mol m －２ s －１ or more, or 200 x 10 for sulfuric acid －８ mol m －２ s －１ The upper limit of the hydrogen ion permeation flux is not particularly limited, but for example, it is 70×10 for hydrochloric acid. －８ mol m －２ s －１ , or 600 x 10 for sulfuric acid －８ mol m －２ s －１ In addition, the anion exchange membrane of the present invention has a membrane resistance of 0.5 Ωcm as measured using 0.5 M NaCl. ２ Preferably, the NaCl permeability (salt flux) in a diffusion dialysis system measured using 3M NaCl is 1.0 x 10 or less. －４ mol m －２ s －１ The specific methods for measuring the membrane resistance and salt flux are as described in the Examples.

[0012] In the bipolar membrane electrodialysis device of the present invention, an anion exchange membrane, an acid chamber where acid is produced, a bipolar membrane, an alkali chamber where alkali is produced, a cation exchange membrane, and a brine chamber to which brine is supplied are configured as one unit, and an ion exchange section is configured by arranging a plurality of such units. Figure 2 is a schematic diagram showing the configuration of the unit. In Figure 2, electrodes are arranged at both ends of the ion exchange section, and an electrode solution is supplied to the electrode chamber in which the electrodes are arranged. In Figure 2, AEM represents the anion exchange membrane, BP represents the bipolar membrane, and CEM represents the cation exchange membrane. MA represents the M ＋ and A－ or M ＋ and A ２－ The salt (MA) is separated into two compartments, and an aqueous solution of salt (MA) is supplied to the brine compartment. In FIG. 2, water is supplied to the acid compartment and the alkaline compartment, but water or an aqueous solution containing salt may be supplied to the acid compartment and the alkaline compartment, and the salt may be the same as or different from the salt supplied to the brine compartment. When an aqueous solution containing salt is supplied to the acid compartment and the alkaline compartment, it is preferable that the salt concentration is lower than that of the aqueous solution of salt supplied to the brine compartment. The salt concentration of the brine supplied to the brine compartment is preferably 0.5 to 2.0 mol / L, and the salt concentration of the aqueous solutions supplied to the acid compartment and the alkaline compartment is preferably 0.0001 to 1.0 mol / L. In the acid compartment, A that has permeated the AEM from the brine compartment and moved to the acid compartment is － or A ２－ and H generated by BP ＋ The concentration of M increases and an acid is generated. In the alkaline chamber, M ＋ and OH generated by BP － The concentration of increases and alkali is generated. ＋ A part of the salt moves through the AEM to the brine chamber, and a part of the salt moves through the CEM to the alkaline chamber. For example, on the right side of the first unit shown in Figure 2, the AEM, acid chamber, BP, and the next unit are placed to the right of the right brine chamber. ＋ A portion of the solution passes through the AEM and moves to the brine compartment of the first unit, and a portion of the solution passes through the CEM and moves to the alkaline compartment. An acid-containing aqueous solution is discharged from the acid compartment, and an alkali-containing aqueous solution is discharged from the alkaline compartment. The bipolar membrane electrodialysis device of the present invention may be provided with supply units and tanks for various solutions that supply various solutions to the brine compartment, acid compartment, alkaline compartment, and electrode compartment, and a discharge unit that discharges the various solutions from each of the compartments, and the various solutions discharged from each of the compartments may be supplied again to each compartment and circulated.

[0013] In the present invention, the alkali production unit refers to the electric power unit calculated by the following formula (1): In the following formula, the electric power unit is calculated for NaOH, but to calculate the electric power unit for other hydroxides (alkali), the "amount of NaOH (kg) per mole" in the following formula (1) can be replaced with the amount of other hydroxide (kg) per mole.

[0014]

[0015] The current efficiency in the present invention is calculated by the following formula (2): In formula (2), the mole change is the mole change of the alkali produced, the current is the current (amperes) passed in the alkali production, and the time is the time (seconds) required for the alkali production.

[0016]

[0017] The method for operating a bipolar membrane electrodialysis device of the present invention is a method for operating a bipolar membrane electrodialysis device that includes a bipolar membrane, a cation exchange membrane, and an anion exchange membrane as ion exchange membranes, and that produces an acid and an alkali by supplying brine to the bipolar membrane electrodialysis device. The anion exchange membrane to be used is selected based on the hydrogen ion flux of the anion exchange membrane for hydrochloric acid or the hydrogen ion flux of the anion exchange membrane for sulfuric acid, depending on the type of salt in the brine to be supplied and / or the alkali concentration during operation. －８ mol m －２ s －１ The above anion exchange membrane and 7 × 10 －８ mol m －２ s －１ When selecting an anion exchange membrane to be used based on the hydrogen ion permeation flux for sulfuric acid, the anion exchange membrane having a hydrogen ion permeation flux of 150×10 －８ mol m －２ s －１ Anion exchange membrane and 150 x 10 －８ mol m －２ s －１It is preferable to select either an anion exchange membrane having a hydrogen ion permeation flux of 7×10 or less for hydrochloric acid. －８ mol m －２ s －１ An anion exchange membrane having a hydrogen ion permeation flux of less than 1.0 × 10 －８ mol m －２ s －１ 7 x 10 or more －８ mol m －２ s －１ an anion exchange membrane of less than 1.0 x 10 －８ mol m －２ s －１ The anion exchange membrane is divided into two groups, one with a hydrogen ion permeation flux of 150×10 and the other with a hydrogen ion permeation flux of 150×10. －８ mol m －２ s －１ An anion exchange membrane having a hydrogen ion permeation flux of less than 40×10 －８ mol m －２ s －１ Above 150 x 10 －８ mol m －２ s －１ an anion exchange membrane of less than 40×10 －８ mol m －２ s －１ The anion exchange membrane is divided into two sections, one with a hydrogen ion permeation flux of 7×10 for hydrochloric acid and the other with a hydrogen ion permeation flux of 7×10 for hydrochloric acid. －８ mol m －２ s －１ When selecting an anion exchange membrane having a hydrogen ion permeation flux of 10×10 for hydrochloric acid, －８ mol m －２ s －１ It is preferable to select an anion exchange membrane having a hydrogen ion permeation flux of 150×10 or more for sulfuric acid. －８ mol m －２ s －１ When selecting an anion exchange membrane having a hydrogen ion permeation flux of 200×10 －８ mol m －２ s－１ It is preferable to select the above anion exchange membranes.

[0018] Here, the anion exchange membranes when the hydrogen ion permeation flux is divided as described above are classified into high H ＋ Permeable membrane, medium H ＋ Permeable membrane, low H ＋ In the case of a permeable membrane, according to the operating method of the present invention, for example, an anion with low mobility in an anion exchange membrane, such as sulfate, is used as the salt in the brine (for example, SO ４ ２－ When using a salt that generates a divalent or higher valent anion such as a divalent or higher valent anion, regardless of the alkali concentration in the resulting alkaline aqueous solution, ＋ Select a permeable membrane. The salt in the brine is an anion with high mobility in the anion exchange membrane, such as chloride (e.g., Cl). － When using a salt that generates a monovalent anion such as a hydroxyl group, and the alkaline solution is produced at a relatively low alkaline concentration, high H ＋ If a permeable membrane is selected and operation is performed in a higher alkaline concentration range, ＋ Permeable membrane or low H ＋ According to the operation method of the present invention, the anion exchange membrane to be used can be optimized depending on the type of salt in the brine to be supplied and the alkali concentration during operation, thereby reducing the alkali production consumption rate. Conventionally, anion exchange membranes have not been selected based on hydrogen ion permeation flux as in the present invention. The present inventors have developed a method for selecting anion exchange membranes based on high H ion permeation flux, which has not been used conventionally. ＋ H like a permeable membrane ＋ The discovery of a method for producing acids and alkalis using a bipolar membrane electrodialysis device that uses an anion exchange membrane with a high hydrogen ion permeation rate has made it possible for the first time to select an anion exchange membrane based on the hydrogen ion permeation flux in order to reduce the alkali production unit. ＋ By selecting an anion exchange membrane based on the hydrogen ion permeation flux of the permeable membrane, it has become possible to optimize the alkali production consumption rate.

[0019] The anion exchange membrane of the present invention has a hydrogen ion permeation flux of 7×10 －８ mol m －２ s －１ or above or 150 x 10 for sulfuric acid －８ mol m －２ s －１ The bipolar membrane electrodialysis apparatus described above can also be operated in a manner that adjusts the alkali concentration of the aqueous alkaline solution produced during operation depending on the type of salt in the brine supplied. This operation method can optimize the alkali production consumption rate by controlling the alkali concentration depending on the type of salt in the brine supplied and adjusting the alkali concentration to a range where the alkali production consumption rate can be reduced, for example, in cases where the brine is made of sodium sulfate, and the brine is made of sodium chloride, and the alkali production consumption rate can be reduced regardless of the alkali concentration in the aqueous alkaline solution produced.

[0020] The method for producing an acid and alkali, the bipolar membrane electrodialysis apparatus, and the method for operating the bipolar membrane electrodialysis apparatus of the present invention can be used in a carbon recycling process as shown in Figure 1. As shown in Figure 1, calcium is efficiently extracted from calcium-containing waste using an acid solution obtained by acid and alkali regeneration using bipolar membrane electrodialysis, and CO contained in exhaust gases, etc. is removed using an alkaline solution. ２ By reacting the two, CO ２The purpose is to immobilize minerals. The resulting alkaline salt solution, such as NaCl, is used as brine to be supplied to the brine chamber of the bipolar membrane electrodialysis device, and as a solution to be supplied to the acid and alkaline chambers. Acid and alkaline solutions are then produced again by electrodialysis in the bipolar membrane electrodialysis device. This process can be repeated to recycle carbon. According to the operating method of the bipolar membrane electrodialysis device of the present invention, the anion exchange membrane to be used is selected based on the hydrogen ion permeation flux for hydrochloric acid or the hydrogen ion permeation flux for sulfuric acid, depending on the type of alkaline salt solution produced in the carbon recycling process and the alkali concentration of the alkaline solution to be produced. This allows optimization of the alkali production unit. Furthermore, with the recent spread of lithium batteries and other devices, the demand for lithium hydroxide as a lithium source has increased, and high-purity lithium hydroxide is particularly desired. Accordingly, methods have been proposed for producing lithium hydroxide from lithium salts using lithium chloride or lithium sulfate as raw materials via electrodialysis using bipolar membranes. However, it has been difficult to reduce the lithium hydroxide production unit, i.e., the alkali production unit, and thereby improve production efficiency. According to the method for producing an acid and an alkali, the bipolar membrane electrodialysis apparatus, and the method for operating the bipolar membrane electrodialysis apparatus of the present invention, the production unit consumption when producing lithium hydroxide from a solution of a lithium salt such as lithium chloride or lithium sulfate by electrodialysis can be optimized to be low, and lithium hydroxide can be produced with high production efficiency. Therefore, the method for producing an acid and an alkali, the bipolar membrane electrodialysis apparatus, and the method for operating the bipolar membrane electrodialysis apparatus of the present invention can reduce CO ２ It can be suitably used not only for producing alkali for immobilization but also for producing lithium hydroxide.

[0021] The present invention will be described below with reference to examples, but the present invention is not limited to these specific embodiments.

[0022] The properties of the membranes used in the Examples and Reference Examples are shown in Table 1. In Table 1, CSE stands for Neosepta CSE (manufactured by Astom Corporation), ASE stands for Neosepta ASE (manufactured by Astom Corporation), FAS-20 stands for FAS-20 (manufactured by Fumatech), AID stands for Neosepta AID (manufactured by Astom Corporation), and ACM stands for Neosepta ACM (manufactured by Astom Corporation). CSE and ASE are membranes that are typically used as cation exchange membranes and anion exchange membranes, respectively, and ASE is a membrane with a medium H ＋ AID and ACM are generally difficult (low) H ＋ It is called a permeable anion exchange membrane and has low H ＋ It corresponds to a permeable membrane. ＋ This corresponds to the permeable membrane. Ｗ represents the water flux in the diffusion dialysis system, and J Ｓ represents the salt flux in the diffusion dialysis system.

[0023]

[0024] (H ＋ Measurement of permeation flux) H per AEM in electrodialysis ＋ In order to evaluate the permeation flux of H, electrodialysis was carried out using a small cell shown in Figure 3. In this evaluation, a more accurate H ＋ Since it was necessary to keep the pH of the solution constant in order to calculate the permeation flux, all solutions used were used in the dialysis experiment immediately after their preparation. In addition, the laboratory was ventilated to prevent an increase in the carbon dioxide concentration. The sample membrane and end membrane used were immersed twice for 5 minutes in a 0.5 mol / L NaCl aqueous solution, and the experiment was started. Four AEMs used in the Examples and Reference Examples were sandwiched in the sample section as sample membranes, and a CSE used in the Examples and Reference Examples was sandwiched in the end membrane section as end membrane (CEM), and electrodialysis was performed at a constant current of 0.1 A for 30 minutes in a 25°C atmosphere. The effective membrane area was 8 cm ２The electrode solution in the electrode chamber was 1 mol / L NaCl. The volume of each of the electrode chamber, salt solution chamber, and acid solution chamber was 200 mL, and the amount of solution used in each of the electrode chamber, salt solution chamber, and acid solution chamber was 100 mL, and stirring was performed at a rotation speed of 2500 rpm. After the measurement, a current of 0.5 A was passed in the opposite direction to that during measurement for 15 minutes to regenerate the electrode. In this measurement, an aqueous NaCl solution or Na ２ SO ４ The acid solution chamber on the positive side of the sample membrane is filled with an aqueous solution of HCl or H ２ SO ４ The aqueous solution is poured into the chamber, and the pH of the salt solution chamber is continuously measured. ＋ The H concentration is converted into a concentration and the H concentration is calculated over time. ＋ From the gradient of the change in concentration, H is calculated using the following formula (3): ＋ Permeation flux (J ｉ :mol m －２ s －１ In the following formula, V is the volume of the solution placed in the salt solution chamber (m ３ ), and S is the effective membrane area (m ２ ) and ΔC ｉ / Δt is H ＋ The gradient of the concentration change (mol m －３ s －１ Table 2 shows the solution conditions under which the experiment was conducted. Measurements were carried out twice for each condition, and the H values ​​of each film were ＋ The average values ​​of the permeation flux are shown in Table 3.

[0025]

[0026]

[0027]

[0028] (J Ｗ and J Ｓ Measurement of J in Table 1 Ｗ and J Ｓ The method for measuring the water flux J in a diffusion dialysis system is shown in Fig. 4(a) using the apparatus shown in Fig. 4(a) to measure the water permeability and the permeability of secondary ions. Ｗ and salt flux J ＳIn the diffusion dialysis system, the current flowing is zero, so the flux of counterions and secondary ions is equal to the flux of salt, and therefore J Ｓ By measuring this, the permeability of secondary ions can be evaluated. In this device, a sample membrane is sandwiched between two containers, Cell I and Cell II, and a 3M NaCl solution is placed in Cell I, which has a graduated capillary tube, while deionized water is placed in Cell II, and a sensor for measuring conductivity is placed inside. By observing the change in water level Δh in the capillary tube of Cell I at predetermined measurement times, the volume change ΔV = Δh × a (a is the cross-sectional area of ​​the capillary tube) is measured, and J is calculated from the equation in Figure 4(a). Ｗ In addition, the conductivity change is measured at predetermined time intervals using a conductivity meter placed in Cell II, and the NaCl concentration change ΔC is calculated from this value. By substituting this value into the equation in FIG. 4(a), J Ｓ The temperature during the measurement was 25°C.

[0029] (Measurement of membrane resistance) The method for measuring the membrane resistance in Table 1 is shown below. Figure 4(b) shows the measurement device and measurement conditions for membrane resistance. First, a platinum electrode was placed on a membrane with a current-carrying area of ​​0.949 cm. ２ An aqueous NaCl solution (NaCl concentration 0.5 mol / L) was placed in an acrylic cell as a measurement solution, and the solution resistance (R ０ After that, the sample film was sandwiched between the two cells, and the resistance (R １ The membrane resistance (R ｍ ) to R ｍ =R １ -R ０ It was calculated from the formula: １ [Ω cm ２ ] is the resistance measured by sandwiching the sample film between two cells, and R ０ [Ω cm ２ ] is the solution resistance measured without sandwiching the sample film, and R ｍ [Ω cm ２ ] is the membrane resistance.

[0030] (Measurement of Cation Transference Number) The cation transference number was measured by the following method. The membrane to be measured was a membrane having an effective membrane area of ​​8.0 cm as shown in FIG. ２The tube was sandwiched between two cells of an electrodialysis device (2.0 cm x 4.0 cm), and 100 mL of 0.5 M NaCl solution was placed in each cell. A silver chloride electrode was used as the negative electrode and a silver electrode as the positive electrode, and the tube was subjected to a current of 10 mA / cm under an atmosphere of 25°C. ２ Electrodialysis was performed by applying a direct current at a current density of t for 75 minutes. Thereafter, the measurement solutions in the two cells were taken out and diluted with a 300 mL measuring flask. The conductivity was measured using a conductivity meter, and the change in the number of moles, Δm, during electrodialysis was calculated from the conductivity. This Δm was calculated as t ＋ The dynamic transport number was calculated by substituting the formula t = Δm / Ea, and this was taken as the cation transport number. ＋ represents the dynamic transport number, Δm represents the transfer equivalent (the change in the number of moles during electrodialysis), Ea represents the theoretical equivalent (= I × t / F), I represents the current [A], t represents the electrodialysis time [s], and F represents the Faraday constant [C / mol]. As a result of the measurement, the cation transport number of CSE was found to be 0.98.

[0031] Examples 1 to 5 Acid-alkali generation experiments were carried out using a benchtop bipolar membrane electrodialysis device using the ion exchange membrane unit shown in Figure 2. This device has 10 pairs of cells, with the AEM, acid chamber, BP, alkaline chamber, CEM, and brine chamber being considered as one pair of cells (units) in the schematic diagram of the bipolar membrane electrodialysis device shown in Figure 2. The effective membrane area per membrane was 55 cm. ２The electrodialysis device has nickel electrodes and electrode chambers at both ends. The equipment conditions used are shown in Figure 5(a). Figure 5(b) shows the experimental conditions. In the experiment, the specified salt solution (brine water), acid solution (supply solution to the acid chamber), alkaline solution (supply solution to the alkaline chamber), and electrode solution shown in Figure 5(b) were supplied to each chamber by pumps and circulated through the salt water tank, acid solution tank, alkaline solution tank, and electrode solution tank, respectively. As ions move in the electrodialysis experiment, the water that hydrates the ions (hydration water) also moves. Therefore, in the experiment, each tank was placed on an electronic balance, and the change in volume over time was calculated from the change in weight. In this experiment, a CSE was used as the cation exchange membrane (CEM), and a Neosepta BPU (manufactured by Astom Corporation) was used as the bipolar membrane. Furthermore, an FAS-20 was used as the anion exchange membrane (AEM). Example 1 is an example in which KCl was used as the salt in the brine, Example 2 is an example in which NaCl was used, Example 3 is an example in which LiCl was used, and Example 4 is an example in which Na ２ SO ４ An example using Li ２ SO ４ Example 5 is an example in which an aqueous solution of the same salt as the salt in the brine supplied to the salt chamber was supplied to the alkaline chamber and the acid chamber in each example. However, the initial salt concentrations of the aqueous solutions supplied to each chamber were 1.0 M in the salt chamber, 0.001 M in the alkaline chamber, and 0.001 M in the acid chamber. 1.0 M NaOH was used as the electrode solution. The initial liquid volume of each of these solutions was 500 mL. The initial liquid volume is the total liquid volume in each chamber, each liquid tank, and the piping connecting each chamber to each liquid tank. Electrodialysis was carried out by using an aqueous solution of LiCl and Li ２ SO ４ In experiments using aqueous solutions, a constant current of 3.0 A was used, and in experiments using other salt solutions, a constant current of 4.4 A was used. The change in concentration over time in each tank was measured using a pH meter or a conductivity meter and recorded on a logging PC. The ion concentration, solution volume, inter-electrode voltage, and inter-platinum electrode voltage in each solution tank were measured over the course of electrodialysis.

[0032] [Reference Examples 1 to 3] In Reference Examples 1 to 3, experiments were carried out in the same manner as in Example 1, except that the anion exchange membranes used were changed. The anion exchange membranes used in Reference Examples 1 to 3 were ASE, AID, and ACM, respectively.

[0033] [Reference Examples 4 to 6] In Reference Examples 4 to 6, experiments were carried out in the same manner as in Example 2, except that the anion exchange membranes used were changed. The anion exchange membranes used in Reference Examples 4 to 6 were ASE, AID, and ACM, respectively.

[0034] [Reference Examples 7 to 9] In Reference Examples 7 to 9, experiments were carried out in the same manner as in Example 3, except that the anion exchange membranes used were changed. The anion exchange membranes used in Reference Examples 7 to 9 were ASE, AID, and ACM, respectively.

[0035] [Reference Examples 10 to 12] In Reference Examples 10 to 12, experiments were carried out in the same manner as in Example 4, except that the anion exchange membranes used were changed. The anion exchange membranes used in Reference Examples 10 to 12 were ASE, AID, and ACM, respectively.

[0036] Reference Examples 13 to 15 were carried out in the same manner as in Example 5, except that the anion exchange membranes used were changed. The anion exchange membranes used in Reference Examples 13 to 15 were ASE, AID, and ACM, respectively.

[0037] (Cell Voltage) The cell voltage is the voltage across one cell (one unit) composed of the AEM, acid compartment, bipolar membrane (BP), alkaline compartment, CEM, and brine compartment shown in Figure 2. In this experiment, platinum band electrodes were inserted in contact with the membrane on the anode compartment side of the membrane adjacent to the anode electrode compartment (anode compartment) and on the cathode compartment side of the membrane adjacent to the cathode electrode compartment (cathode compartment). The cell voltage was calculated by dividing the voltage between these two platinum band electrodes by a logarithm (here, 10 pairs) during the experiment. Figures 6 and 7 show the relationship between cell voltage and alkaline solution concentration. The vertical axis of each graph represents cell voltage, and the horizontal axis represents the alkaline concentration of the alkaline aqueous solution produced in the alkaline compartment. Figure 6(a) shows the results of Example 1 and Reference Examples 1 to 3, where KCl was used as the salt in the brine; Figure 6(b) shows the results of Example 2 and Reference Examples 4 to 6, where NaCl was used as the salt in the brine; and Figure 6(c) shows the results of Example 3 and Reference Examples 7 to 9, where LiCl was used as the salt in the brine. Figure 7(a) shows the salt content of saltwater.２ SO ４ 7(b) shows the results of Example 4 and Reference Examples 10 to 12 in which Li was used as the salt in the brine. ２ SO ４ The results of Example 5 and Reference Examples 13 to 15, in which KCl, NaCl, and LiCl were used as salts, are shown below. When KCl, NaCl, and LiCl were used as salts, in both the Examples and Reference Examples, the cell voltage initially decreased and then increased after reaching a certain value. This is because, over time, alkali and acid are generated in the aqueous salt solution in the alkaline and acid compartments, respectively, with an initial salt concentration of 0.001 M, and it takes time for these to circulate within the device and reach a uniform concentration. The increase in cell voltage in the latter half is due to the decrease in conductivity of the brine in the salt compartment, which has an initial concentration of 1 M, being desalinated over time. When Na was used as salt, ２ SO ４ and Li ２ SO ４ When the salt is KCl, NaCl, and LiCl, the cell voltage initially drops and then remains at a constant value. Comparing the cell voltages when the salt is KCl, NaCl, and LiCl, in the case of KCl and NaCl, FAS-20<ASE=ACM<AID is satisfied in almost all alkaline concentration ranges. In the case of LiCl, FAS-20<ASE<AID<ACM is satisfied in almost all alkaline concentration ranges. ２ SO ４ and Li ２ SO ４ In the case of FAS-20, the cell voltage was FAS-20<ASE<ACM<AID in all alkaline concentration ranges. When comparing the cell voltage when chloride salts were used and when sulfate salts were used, the cell voltage was higher in the case of sulfate salts than when chloride salts were used, except for FAS-20, and the cell voltage was particularly high when AID was used with sulfate salts. This is because Cl － and SO ４ ２－ In the case of Cl, the mobility in the film is －Here, in the descriptions of the cell voltage and the alkaline current efficiency and alkaline production unit consumption described below, "<" means that the value when the anion exchange membrane on the right side is used is higher than the value when the anion exchange membrane on the left side is used, and "=" means that the value when the anion exchange membrane on the right side is used is almost the same as the value when the anion exchange membrane on the left side is used.

[0038] (Current efficiency) Figures 8 and 9 show the relationship between the current efficiency of alkali generation (alkaline current efficiency) and the alkali generation concentration. The vertical axis of the figure shows the current efficiency, and the horizontal axis shows the alkali concentration of the alkaline aqueous solution generated in the alkaline chamber. Figure 8(a) shows the results of Example 1 and Reference Examples 1 to 3, in which KCl was used as the salt in the brine; Figure 8(b) shows the results of Example 2 and Reference Examples 4 to 6, in which NaCl was used as the salt in the brine; and Figure 8(c) shows the results of Example 3 and Reference Examples 7 to 9, in which LiCl was used as the salt in the brine. Figure 9(a) shows the results of Example 1 and Reference Examples 1 to 3, in which NaCl was used as the salt in the brine. ２ SO ４ 9(b) shows the results of Example 4 and Reference Examples 10 to 12 in which Li was used as the salt in the brine. ２ SO ４ The results are shown for Example 5 and Reference Examples 13 to 15, in which NaCl was used. In both Examples and Reference Examples, the alkaline current efficiency increases at low alkali concentrations because, although acid and alkali are generated by passing a current through the device, it takes time for the generated acid and alkali to spread uniformly within the device, resulting in a low alkaline current efficiency in the initial stage. Excluding this range, the current efficiency when NaCl is used is close to 100%, but this value decreases as the alkali concentration increases. When KCl and LiCl are used, the current efficiency also decreases as the alkali concentration increases, and in all cases of KCl, NaCl, and LiCl, the degree of decrease in current efficiency is greatest for FAS-20, followed by ASE. In almost all alkaline concentration ranges, the current efficiency values ​​are FAS-20<ASE<AID<ACM when KCl is used, FAS-20<ASE<AID=ACM when NaCl is used, and FAS-20<ASE=ACM<AID when LiCl is used. ２ SO４ and Li ２ SO ４ In the case of (1), the alkaline current efficiency was low in the early stage of operation, then increased on the low concentration side, and decreased as the alkaline concentration increased. However, FAS-20, ASE, ACM, and AID showed the same level of current efficiency in almost all alkaline concentration ranges, and the rate of decrease in current efficiency due to an increase in alkaline concentration was also almost the same.

[0039] (Alkali production unit consumption) Figures 10 and 11 show the relationship between the power consumption unit for alkali production (alkali production unit consumption) and the alkali production concentration. The vertical axis of the figure shows the power consumption unit, and the horizontal axis shows the alkali concentration of the alkaline aqueous solution produced in the alkaline chamber. Figure 10(a) shows the results of Example 1 and Reference Examples 1 to 3 in which KCl was used as the salt in the brine, Figure 10(b) shows the results of Example 2 and Reference Examples 4 to 6 in which NaCl was used as the salt in the brine, and Figure 10(c) shows the results of Example 3 and Reference Examples 7 to 9 in which LiCl was used as the salt in the brine. Figure 11(a) shows the results of Example 1 and Reference Examples 1 to 3 in which NaCl was used as the salt in the brine, and Figure 11(c) shows the results of Example 3 and Reference Examples 7 to 9 in which LiCl was used as the salt in the brine. ２ SO ４ 11(b) shows the results of Example 4 and Reference Examples 10 to 12 in which Li was used as the salt in the brine. ２ SO ４ The results of Example 5 and Reference Examples 13 to 15 using KCl and LiCl are shown below. The sudden drop in the consumption rate on the low concentration side is a phenomenon that accompanies the increase in current efficiency shown in Figures 8 and 9, and is thought to be due to the fact that the generated alkali is not uniformly spread in the alkali side tank at the beginning of operation. When KCl, NaCl, or LiCl was used as the salt, the consumption rate of FAS-20 was the lowest in the low alkali concentration range. In the range of higher alkali concentrations, when KCl and NaCl were used, the consumption rate of ACM was the lowest, and ASE and AID were almost the same values. When LiCl was used as the salt, ASE and AID were almost the same and were the lowest. When NaCl was used as the salt, ２ SO ４ and Li ２ SO ４In all cases, when FAS-20 was used, it showed the lowest unit consumption over the entire range of alkali concentrations, with the order being FAS-20 < ASE < ACM < AID. As shown in Figures 10 and 11, it is possible to select an anion exchange membrane that can minimize the unit consumption of alkali production based on the difference in hydrogen ion permeation flux, depending on the type of salt and the alkali concentration of the alkaline aqueous solution to be obtained by operating the bipolar membrane electrodialysis device. For example, when a monovalent acid salt such as NaCl is used as the salt in the brine, an anion exchange membrane with a large hydrogen ion permeation flux and a high H ＋ When using a permeable membrane and operating in a higher concentration range, low H ions with a small hydrogen ion permeation flux such as ACM or AID are used. ＋ A permeable membrane is used, and in some cases, a medium H ＋ There is an option to use a permeable membrane. ２ SO ４ When using a salt of a divalent or higher valent acid such as FAS-20, regardless of the alkali concentration during operation, a high H ＋ It is possible to select an anion exchange membrane. The higher the hydrogen ion permeation flux of the anion exchange membrane, the lower the cell voltage, which leads to a reduction in the alkali production consumption. However, the higher the hydrogen ion permeation flux, the lower the alkali current efficiency, and the degree of this decrease is particularly large in the region of high alkali production concentration. Therefore, depending on the type of salt in the brine, the alkali production consumption may be reversed in the region of high alkali production concentration, and high H ＋ In some cases, the alkali production unit consumption is lower with other permeable membranes than with permeable membranes. When operating in such an alkali production concentration range, ＋ Permeable membrane and low H ＋By using a permeable membrane, the alkali production consumption rate can be reduced. In addition, the higher the hydrogen ion permeation flux of the anion exchange membrane, the lower the alkali production consumption rate at low alkali production concentrations. However, if the hydrogen ion permeation flux becomes too high, the alkali production concentration range in which the alkali production consumption rate can be reduced becomes narrow. Therefore, in a practical alkali production concentration range, high H ＋ An upper limit for the hydrogen ion permeation flux of the permeable membrane can be determined.

[0040] (Acid production unit) Figure 12 shows the relationship between the power consumption unit for acid production (acid production unit) and the acid production concentration. The vertical axis of the figure shows the power consumption unit, and the horizontal axis shows the acid concentration (H ＋ 12(a) shows the results of Example 1 and Reference Examples 1 and 2, in which KCl was used as the salt in the brine; FIG. 12(b) shows the results of Example 2 and Reference Examples 4 and 5, in which NaCl was used as the salt in the brine; and FIG. 12(c) shows the results of Example 2 and Reference Examples 4 and 5, in which NaCl was used as the salt in the brine. ２ SO ４ The results of Example 4 and Reference Examples 10 and 11 using the same are shown below. Table 4 also shows the numerical values ​​of each measurement result.

[0041]

[0042] Salts include KCl, NaCl, and Na ２ SO ４ When either of the above salts was used, the consumption unit of FAS-20 was the lowest in the low acid concentration range. In the higher acid concentration range, when KCl and NaCl were used, the ASE and AID were almost the same. ２ SO ４In all cases, when FAS-20 was used, it showed the lowest unit consumption over the entire range of acid concentrations, with the order being FAS-20 < ASE < AID. As shown in Figure 12, based on the difference in hydrogen ion permeation flux, it is possible to select an anion exchange membrane that can minimize the unit consumption of acid production depending on the type of salt and the acid concentration of the acid aqueous solution to be obtained by operating the bipolar membrane electrodialysis device. For example, when a monovalent acid salt such as NaCl is used as the salt in the brine, an anion exchange membrane with a large hydrogen ion permeation flux and a high H ＋ When using a permeable membrane and operating in a higher concentration range, a medium H ＋ A permeable membrane is used, and in some cases, a low H ＋ There is an option to use a permeable membrane. ２ SO ４ When using a salt of a divalent or higher valent acid such as FAS-20, regardless of the acid concentration during operation, a high H ＋ The use of a permeable membrane can be selected. The higher the hydrogen ion permeation flux of the anion exchange membrane, the lower the cell voltage, which leads to a reduction in the acid production unit. However, the higher the hydrogen ion permeation flux, the lower the acid current efficiency, and the degree of this decrease is particularly large in the region of high acid production concentration. Therefore, depending on the type of salt in the brine, in the region of high acid production concentration, high H ＋ Permeable membrane and medium H ＋ Permeable membrane or low H ＋ When operating in such an acid production concentration range, the acid production consumption rate may be almost the same as that of the permeable membrane, or may be reversed. ＋ Permeable membrane and low H ＋ By using a permeable membrane, the acid production consumption rate can be reduced. In addition, the higher the hydrogen ion permeation flux of the anion exchange membrane, the lower the acid production consumption rate at low acid production concentrations. However, if the hydrogen ion permeation flux becomes too high, the acid production concentration range in which the acid production consumption rate can be reduced becomes narrow. Therefore, in a practical acid production concentration range, high H＋ An upper limit for the hydrogen ion permeation flux of the permeable membrane can be determined.

[0043] The method for producing an acid and an alkali, the bipolar membrane electrodialysis apparatus, the anion exchange membrane, and the method for operating the bipolar membrane electrodialysis apparatus of the present invention can reduce the alkali production consumption rate or the acid production consumption rate, or the alkali production consumption rate and the acid production consumption rate, and can be suitably used in a carbon recycling process, etc. They can also be suitably used in the production of lithium hydroxide.

Claims

1. A method for producing an acid and an alkali by supplying brine to a bipolar membrane electrodialysis device equipped with a bipolar membrane, a cation exchange membrane, and an anion exchange membrane as ion exchange membranes, and performing electrodialysis to produce an acid and an alkali, wherein the hydrogen ion permeation flux of the anion exchange membrane is 7 x 10 for hydrochloric acid. －８ mol m －２ s －１ or above or 150 x 10 for sulfuric acid －８ mol m －２ s －１ The above method for producing an acid and an alkali.

2. A bipolar membrane electrodialysis device equipped with a bipolar membrane, a cation exchange membrane, and an anion exchange membrane as ion exchange membranes, wherein the anion exchange membrane, an acid chamber in which acid is produced, the bipolar membrane, an alkali chamber in which alkali is produced, the cation exchange membrane, and a brine chamber to which brine is supplied are treated as one unit, and an ion exchange section is formed by arranging a plurality of such units, and the anion exchange membrane has a 7 x 10 －８ mol m －２ s －１ or above or 150 x 10 for sulfuric acid －８ mol m －２ s －１ A bipolar membrane electrodialysis device using an anion exchange membrane having a hydrogen ion permeation flux of 1000 or more.

3. A bipolar membrane electrodialysis device equipped with a bipolar membrane, a cation exchange membrane, and an anion exchange membrane as ion exchange membranes, wherein the anion exchange membrane, the acid chamber where acid is produced, the bipolar membrane, the alkali chamber where alkali is produced, the cation exchange membrane, and the brine chamber to which brine is supplied are made into one unit, and a plurality of such units are arranged to form an ion exchange section. This bipolar membrane electrodialysis device is used for 7 x 10 hydrochloric acid. －８ mol m －２ s －１ or above or 150 x 10 for sulfuric acid －８ mol m －２ s －１ An anion exchange membrane having a hydrogen ion permeation flux of 1000 kJ / cm or more.

4. A method for operating a bipolar membrane electrodialysis device that produces acid and alkali by supplying brine to a bipolar membrane electrodialysis device equipped with a bipolar membrane, a cation exchange membrane, and an anion exchange membrane as ion exchange membranes, wherein the anion exchange membrane to be used is selected based on the hydrogen ion permeation flux of the anion exchange membrane relative to hydrochloric acid or the hydrogen ion permeation flux of the anion exchange membrane relative to sulfuric acid, depending on the type of salt in the brine to be supplied and / or the alkalinity during operation.

5. When selecting based on the hydrogen ion permeation flux for hydrochloric acid, the hydrogen ion permeation flux is 7 x 10 －８ mol m －２ s －１ The above anion exchange membrane and 7 × 10 －８ mol m －２ s －１ When selecting an anion exchange membrane to be used based on the hydrogen ion permeation flux for sulfuric acid, an anion exchange membrane having a hydrogen ion permeation flux of 150×10 －８ mol m －２ s －１ Anion exchange membrane and 150 x 10 －８ mol m －２ s －１ 5. The method for operating a bipolar membrane electrodialysis apparatus according to claim 4, wherein either one of anion exchange membranes having a molecular weight of 1000 or less is selected as the anion exchange membrane to be used.

6. A method for operating a bipolar membrane electrodialysis apparatus according to claim 4 or 5, wherein the brine produced by a carbon recycling process using the bipolar membrane electrodialysis apparatus according to claim 4 or 5 is used as the brine to be supplied to said bipolar membrane electrodialysis apparatus.

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