Method for preparing ferulic acid and arginine composite salt through self-desalting bipolar membrane electrodialysis

Abstract

The invention discloses a method for preparing ferulic acid and arginine composite salt by self-desalting bipolar membrane electrodialysis, which adopts a bipolar membrane electrodialysis device for preparation, and the device comprises an anode plate, a cathode plate and a middle membrane stack, an anode, an anode chamber, a bipolar membrane, an acid chamber, a cation exchange membrane, a salt chamber, an anion exchange membrane, an alkali chamber, n, a bipolar membrane and a cathode chamber are sequentially arranged from the anode to the cathode; the preparation method comprises the following steps: S1, adding an alcohol-water solution of sodium ferulate into an acid chamber, adding a sodium chloride solution into a salt chamber, adding an L-Arg hydrochloride solution into an alkali chamber, and adding a sodium sulfate solution into an anode chamber and a cathode chamber; s2, each chamber is adjusted to be at a constant temperature, and self-circulation is started; s3, applying direct current; and S4, stopping electrifying when the conductivity of the alkali chamber is reduced to 1-2.5 mS / cm, and mixing the feed liquid in the acid chamber with the feed liquid in the alkali chamber to prepare the ferulic acid and arginine composite salt with the purity as high as 99%. Meanwhile, high-concentration and high-purity sodium chloride byproducts can be obtained in the self-desalting process, and the economic benefits and the environmental benefits of the technological process are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of pharmaceutical engineering, and particularly relates to a method for preparing ferulic acid arginine complex salt by self-desalting bipolar membrane electrodialysis. Background Art

[0002] Ferulic acid belongs to one of the phenolic acids and has two structures, cis and trans. It is widely present in nature and is contained in many plants such as Umbelliferae, Ranunculaceae, and Gramineae. For example, Angelica sinensis, Ligusticum chuanxiong, Cimicifuga foetida, Sparganium stoloniferum, etc. are the active ingredients in many traditional Chinese medicine herbs. Many studies have shown that ferulic acid has strong antioxidant properties and can effectively scavenge hydrogen peroxide, hydroxyl radicals, and superoxide radicals. At the same time, it also has the function of regulating physiological functions. In addition, ferulic acid also has the effects of antibacterial and anti-inflammatory, preventing and treating coronary heart disease, protecting women's ovaries, and inhibiting liver damage, and is also a cancer-preventive substance recognized internationally in recent years. Ferulic acid is easily absorbed by the human body, has low toxicity, and is relatively safe to use. Its medicinal value has been increasingly emphasized.

[0003] Currently, sodium ferulate is commonly used clinically, but the stability of its sodium salt is very unsatisfactory. Especially when it is made into an injection, its content will rapidly decrease after being placed, which brings great inconvenience to production, storage, circulation, and clinical application. In order to solve the problem of poor stability of sodium ferulate, it is found that the amino acid salt and hydrate of ferulic acid can greatly improve its stability. Patent CN101195570B proposes that using ferulic acid as a raw material, adding 95% ethanol and sodium bisulfite, slowly heating and stirring until dissolved, then adding an aqueous solution containing amino acids, adjusting the pH, adding activated carbon for decolorization after stirring, filtering and freezing crystallization, washing the filter cake with absolute ethanol, and vacuum drying to obtain the crude product of ferulic acid amino salt. Dissolving the above crude product in deionized water, adding activated carbon, filtering and decolorizing, and then adding acetone to precipitate a large amount of white crystals, and obtaining the refined product after standing and filtering. However, this process has cumbersome procedures, will introduce a large amount of impurities, consumes a large amount of organic solvents, and needs to be further optimized. Summary of the Invention

[0004] In view of the above problems, the present invention provides a method for preparing ferulic acid arginine complex salt by self-desalting bipolar membrane electrodialysis. This method has the advantages of no consumption of chemical reagents, high production efficiency, low energy consumption, etc., and can directly prepare high-purity ferulic acid arginine complex salt.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for preparing ferulic acid arginine complex salt by self-desalting bipolar membrane electrodialysis. The method for preparing ferulic acid arginine complex salt is prepared by a bipolar membrane electrodialysis device. The bipolar membrane electrodialysis device includes an anode plate, a cathode plate and a membrane stack placed between the anode plate and the cathode plate. The membrane stack is composed of n groups of electrodialysis units connected in series. The device from the anode to the cathode direction is: anode - anode chamber - [bipolar membrane - acid chamber - cation exchange membrane - salt chamber - anion exchange membrane - alkali chamber]n - bipolar membrane - cathode chamber;

[0007] The method for preparing ferulic acid arginine complex salt includes the following steps:

[0008] S1. Add an aqueous solution of sodium ferulate in alcohol to the acid chamber, add a sodium chloride solution to the salt chamber, add an L-Arg hydrochloride solution to the alkali chamber, and add a sodium sulfate solution to the anode chamber and the cathode chamber;

[0009] S2. Adjust the temperature of the solutions in each chamber to a constant temperature and start the self-circulation of each chamber;

[0010] S3. Apply a direct current between the anode plate and the cathode plate for electrodialysis;

[0011] S4. Stop power supply when the conductivity of the alkali chamber drops to 1.5 ± 1 mS / cm, and then mix the feed liquid in the acid chamber and the feed liquid in the alkali chamber evenly to obtain ferulic acid arginine complex salt.

[0012] The present invention designs a new membrane stack configuration for preparing ferulic acid arginine complex salt. The difficulty of the electrodialysis method lies in how to combine two charged organic ions under the action of an electric field. By investigating different membrane types, the present invention explores the removal of inorganic ions and the leakage of organic ions. When the conductivity of the alkali chamber drops to 1.5 ± 1 mS / cm, the pH in the acid chamber is in the range of 2 - 3, and the pH in the alkali chamber is in the range of 10 - 11. Then, the feed liquid in the acid chamber and the feed liquid in the alkali chamber are mixed evenly. The pH of the mixed solution is in the range of 7.1 - 7.9. At this time, all ferulic acid anions carry negative charges, and most arginines carry one positive charge, and the content of inorganic ions is very small. The product obtained after mixing is ferulic acid arginine complex salt. In the traditional process, the raw materials are ferulic acid and arginine; the present invention directly prepares from their corresponding salts, saving the operation process and avoiding the consumption of acid and base reagents, and having advantages such as high removal rate of impurity ions, high production efficiency, and low energy consumption. At the same time, in order to improve the solubility of ferulic acid, experiments are carried out in an alcohol-water system and equipped with a constant temperature heating device to improve the production efficiency of the process. In addition, the inorganic salts obtained from the self-desalting process can be recovered as by-products, avoiding the discharge of high-salt wastewater and enhancing the economic and environmental benefits of the process.

[0013] Preferably, the aqueous solution of alcohol is n-propanol - water, and the volume ratio of alcohol to water in the aqueous solution of alcohol is 50:50.

[0014] Preferably, the concentration of the aqueous solution of sodium ferulate in the acid chamber is 0.1 - 0.5 mol / L.

[0015] Preferably, the concentration of the sodium chloride solution in the salt chamber is 0.1 mol / L.

[0016] Preferably, the concentration of the L-Arg hydrochloride solution in the alkali chamber is 0.1 - 0.5 mol / L; the concentration of the sodium sulfate solution is 0.1 - 0.6 mol / L.

[0017] Preferably, the temperature of the solutions in each chamber is adjusted to 30 ± 1 - 40 ± 1 °C, and the linear velocity of the solution flow is 1 - 10 cm / s.

[0018] Preferably, the cation exchange membrane used in the membrane stack is CGU, CIMS or C1S; the anion exchange membrane used in the membrane stack is AGU, ACS or A1R.

[0019] Preferably, the bipolar membrane electrodialysis device operates in a constant voltage mode, and the operating voltage is 1 - 4 V for each electrodialysis unit.

[0020] Preferably, the value of n is 1 - 1000.

[0021] Preferably, the bipolar membrane electrodialysis device further includes liquid storage tanks and circulation pumps corresponding to the anode chamber, cathode chamber, acid chamber, salt chamber, and alkali chamber respectively; a constant temperature heating device is provided at the bottom of each liquid storage tank; the anode chamber, cathode chamber, acid chamber, salt chamber, and alkali chamber are each provided with a feed port and a discharge port, and each chamber is connected to the corresponding liquid storage tank through a pipeline and forms a self-circulation loop with its respective circulation pump as the power

[0022] Advantages of the present invention: The raw materials for producing the ferulic acid arginine complex salt in the prior art are ferulic acid and L-Arg, while the raw materials required in the present invention are sodium ferulate and L-Arg hydrochloride, omitting the step of removing impurity ions with ion exchange resin to obtain ferulic acid and L-Arg. In addition, the inorganic ions introduced by the traditional process are difficult to completely remove. Through the bipolar membrane electrodialysis technology, the removal efficiency of these impurity ions is greatly improved, and the consumption of organic reagents is reduced. Therefore, this process is simple, the product purity is high, and it is more energy-saving and environmentally friendly. Description of the Drawings

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention, and those of ordinary skill in the art can also obtain other drawings according to the provided drawings without creative efforts.

[0024] Figure 1 This is a schematic diagram of the principle of preparing ferulic acid arginine complex salt by self-desalting bipolar membrane electrodialysis of the present invention.

[0025] Figure 2 This is the flux of ferulic acid root and arginine root under different membrane types in Examples 1-3 of the present invention.

[0026] Figure 3 This is the flux of ferulic acid root and arginine root under different feed concentrations in the acid chamber and the alkali chamber in Examples 1, 6-8 of the present invention. Detailed implementation manners

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0028] Example 1

[0029] This example uses a bipolar membrane electrodialysis experimental device as shown in Figure 1 which includes an anode plate, a cathode plate, and a membrane stack placed between the anode plate and the cathode plate. An anode chamber and a cathode chamber are respectively formed between the two sides of the membrane stack and the anode plate and the cathode plate; the membrane stack includes 2 groups of electrodialysis units. Each group of electrodialysis units is sequentially arranged in the direction from the anode plate to the cathode plate in the order of a bipolar membrane, a cation exchange membrane, an anion exchange membrane, and a bipolar membrane to form a three-compartment. The compartment on the side close to the anode plate in the three-compartment is denoted as the acid chamber, the middle compartment is the salt chamber, and the compartment on the side close to the cathode plate is denoted as the alkali chamber; it also includes liquid storage tanks and circulation pumps corresponding to the anode chamber, the cathode chamber, the acid chamber, the salt chamber, and the alkali chamber respectively; a constant temperature heating device is provided at the bottom of each liquid storage tank; the anode chamber, the cathode chamber, the acid chamber, the salt chamber, and the alkali chamber are all provided with a feed port and a discharge port, and each chamber is connected to the corresponding liquid storage tank through a pipeline and forms a self-circulation loop with its respective circulation pump as the power;

[0030] From the anode to the cathode direction of the membrane stack is: anode - anode chamber - [bipolar membrane - acid chamber - cation exchange membrane - salt chamber - anion exchange membrane - alkali chamber]n - bipolar membrane - cathode chamber, and the number of repeating units is 2. The anode and cathode materials in the membrane stack are ruthenium-coated titanium with corrosion resistance. Each compartment between adjacent bipolar membranes and cation exchange membranes is composed of a spacer mesh with a flow channel, and the thickness of a single spacer mesh is 0.8 mm. The BP-1 exchange membrane used in the membrane stack is the BP-1 type bipolar membrane produced by ASTOM Company of Japan, and the effective area of a single membrane is 189 cm 2(9 cm × 21 cm). The cation exchange membrane used in the membrane stack can be CGU or CIMS produced by ASTOM Corporation of Japan, or C1S produced by Shandong Tianwei; the anion exchange membrane used in the membrane stack can be AGU or ACS produced by ASTOM Corporation of Japan, or A1R produced by Shandong Tianwei.

[0031] An anode chamber and a cathode chamber are formed between the anode plate and the cathode plate and the adjacent membranes. The anode chamber and the cathode chamber are connected in series. The cation exchange membrane and the anion exchange membrane used in this embodiment are CGU and AGU respectively. 500 mL of 0.3 mol / L sodium sulfate solution is introduced into the electrode chamber as the electrode solution. 500 mL of 0.2 mol / L sodium ferulate solution prepared with n-propanol-water (volume ratio 50:50) is introduced into the acid chamber. 500 mL of 0.1 mol / L sodium chloride solution is introduced into the salt chamber. 500 mL of 0.2 mol / L L-Arg hydrochloride solution is introduced into the alkali chamber. The constant temperature heating devices and self-circulation of each chamber are turned on. The linear flow velocity of each compartment during the process is 4 cm / s. The experiment adopts a constant voltage operation mode, the voltage is set at 6 V, and the operating temperature is controlled at 40 ± 1 °C. The experiment is stopped when the conductivity of the alkali chamber drops to 2.1 mS / cm. After the feed liquids in the acid chamber and the alkali chamber are mixed, the pH is 7.1, and the entire experiment runs for 65 min.

[0032] Example 2

[0033] This example uses the same bipolar membrane electrodialysis experimental device as in Example 1. An anode chamber and a cathode chamber are formed between the anode plate and the cathode plate and the adjacent membranes. The anode chamber and the cathode chamber are connected in series. The cation exchange membrane and the anion exchange membrane used in this embodiment are CIMS and ACS respectively. 500 mL of 0.3 mol / L sodium sulfate solution is introduced into the electrode chamber as the electrode solution. 500 mL of 0.2 mol / L sodium ferulate solution prepared with n-propanol-water (volume ratio 50:50) is introduced into the acid chamber. 500 mL of 0.1 mol / L sodium chloride solution is introduced into the salt chamber. 500 mL of 0.2 mol / L L-Arg hydrochloride solution is introduced into the alkali chamber. The linear flow velocity of each compartment during the experiment is 4 cm / s. The experiment adopts a constant voltage operation mode, the voltage is set at 6 V, and the operating temperature is controlled at 40 ± 1 °C. The experiment is stopped when the conductivity of the alkali chamber drops to 2.5 mS / cm. After the feed liquids in the acid chamber and the alkali chamber are mixed, the pH is 7.5, and the entire experiment runs for 70 min.

[0034] Example 3

[0035] This example uses the same bipolar membrane electrodialysis experimental device as in Example 1. An anode chamber and a cathode chamber are formed between the anode plate and the adjacent membrane, and the anode chamber and the cathode chamber are connected in series. In this example, the cation exchange membrane and the anion exchange membranes C1S and A1R are used. 500 mL of 0.3 mol / L sodium sulfate solution is introduced into the electrode chamber as the electrode solution. 500 mL of 0.2 mol / L sodium ferulate solution prepared with n-propanol-water (volume ratio 50:50) is introduced into the acid chamber. 500 mL of 0.1 mol / L sodium chloride solution is introduced into the salt chamber. 500 mL of 0.2 mol / L L-Arg hydrochloride solution is introduced into the alkali chamber. During the experiment, the linear flow velocity in each compartment is 4 cm / s. The experiment adopts a constant voltage operation mode, the voltage is set to 6 V, and the operating temperature is controlled at 40 ± 1 °C. The experiment stops when the conductivity of the alkali chamber drops to 2.2 mS / cm. After mixing the feed liquids in the acid chamber and the alkali chamber, the pH is 7.24, and the entire experiment runs for 80 min.

[0036] Example 4

[0037] The bipolar membrane electrodialysis device used in this example is the same as that in Example 2.

[0038] An anode chamber and a cathode chamber are formed between the anode plate and the adjacent membrane, and the anode chamber and the cathode chamber are connected in series. 500 mL of 0.3 mol / L sodium sulfate solution is introduced as the electrode solution. 500 mL of 0.2 mol / L sodium ferulate solution prepared with n-propanol-water (volume ratio 50:50) is introduced into the acid chamber. 500 mL of 0.1 mol / L sodium chloride solution is introduced into the salt chamber. 500 mL of 0.2 mol / L L-Arg hydrochloride solution is introduced into the alkali chamber. During the experiment, the linear flow velocity in each compartment is 4 cm / s. The experiment adopts a constant voltage operation mode, the voltage is set to 8 V, and the operating temperature is controlled at 40 ± 1 °C. The experiment stops when the conductivity of the alkali chamber drops to 1.1 mS / cm. After mixing the feed liquids in the acid chamber and the alkali chamber, the pH is 7.28, and the entire experiment runs for 55 min.

[0039] Example 5

[0040] The bipolar membrane electrodialysis device used in this example is the same as that in Example 2.

[0041] An anode chamber and a cathode chamber are formed between the anode plate and the cathode plate and the adjacent membranes. The anode chamber and the cathode chamber are connected in series. 500 mL of a 0.3 mol / L sodium sulfate solution is introduced as the electrode solution. 500 mL of a 0.2 mol / L sodium ferulate solution prepared with n-propanol-water (volume ratio 50:50) is introduced into the acid chamber. 500 mL of a 0.1 mol / L sodium chloride solution is introduced into the salt chamber. 500 mL of a 0.2 mol / L L-Arg hydrochloride solution is introduced into the alkali chamber. During the experiment, the linear flow velocity of each compartment is 4 cm / s. The experiment adopts a constant voltage operation mode, the voltage is set to 10 V, and the operating temperature is controlled at 40 ± 1 °C. The experiment is stopped when the conductivity of the alkali chamber drops to 0.6 mS / cm. After mixing the feed solutions in the acid chamber and the alkali chamber, the pH is 7.63, and the entire experiment runs for 40 min.

[0042] Example 6

[0043] The bipolar membrane electrodialysis device used in this example is the same as that in Example 2.

[0044] An anode chamber and a cathode chamber are formed between the anode plate and the cathode plate and the adjacent membranes. The anode chamber and the cathode chamber are connected in series. 500 mL of a 0.3 mol / L sodium sulfate solution is introduced as the electrode solution. 500 mL of a 0.3 mol / L sodium ferulate solution prepared with n-propanol-water (volume ratio 50:50) is introduced into the acid chamber. 500 mL of a 0.1 mol / L sodium chloride solution is introduced into the salt chamber. 500 mL of a 0.3 mol / L L-Arg hydrochloride solution is introduced into the alkali chamber. During the experiment, the linear flow velocity of each compartment is 4 cm / s. The experiment adopts a constant voltage operation mode, the voltage is set to 8 V, and the operating temperature is controlled at 40 ± 1 °C. The experiment is stopped when the conductivity of the alkali chamber drops to 1.0 mS / cm. After mixing the feed solutions in the acid chamber and the alkali chamber, the pH is 7.93, and the entire experiment runs for 80 min.

[0045] Example 7

[0046] The bipolar membrane electrodialysis device used in this example is the same as that in Example 2.

[0047] An anode plate and a cathode plate form an anode chamber and a cathode chamber with adjacent membranes. The anode chamber and the cathode chamber are connected in series. 500 mL of a 0.2 mol / L sodium sulfate solution is introduced as the electrode solution. 500 mL of a 0.4 mol / L sodium ferulate solution prepared with n-propanol-water (volume ratio 50:50) is introduced into the acid chamber. 500 mL of a 0.1 mol / L sodium chloride solution is introduced into the salt chamber. 500 mL of a 0.4 mol / L L-Arg hydrochloride solution is introduced into the alkali chamber. During the experiment, the flow linear velocity of each compartment is 4 cm / s. The experiment adopts a constant voltage operation mode, with the voltage set at 6 V, and the operating temperature is controlled at 40 ± 1 °C. The experiment stops when the conductivity of the alkali chamber drops to 0.9 mS / cm. After mixing the feed liquids in the acid chamber and the alkali chamber, the pH is 7.76, and the entire experiment runs for 100 min.

[0048] Example 8

[0049] The bipolar membrane electrodialysis device used in this example is the same as that in Example 2.

[0050] An anode plate and a cathode plate form an anode chamber and a cathode chamber with adjacent membranes. The anode chamber and the cathode chamber are connected in series. 500 mL of a 0.3 mol / L sodium sulfate solution is introduced as the electrode solution. 500 mL of a 0.5 mol / L sodium ferulate solution prepared with n-propanol-water (volume ratio 50:50) is introduced into the acid chamber. 500 mL of a 0.1 mol / L sodium chloride solution is introduced into the salt chamber. 500 mL of a 0.5 mol / L L-Arg hydrochloride solution is introduced into the alkali chamber. During the experiment, the flow linear velocity of each compartment is 4 cm / s. The experiment adopts a constant voltage operation mode, with the voltage set at 6 V, and the operating temperature is controlled at 40 ± 1 °C. The experiment stops when the conductivity of the alkali chamber drops to 1.2 mS / cm. After mixing the feed liquids in the acid chamber and the alkali chamber, the pH is 7.97, and the entire experiment runs for 115 min.

[0051] The experimental conditions, the energy consumption of ferulic acid, the energy consumption of L-Arg, the product quality, and the product purity in Examples 1 - 8 are shown in Table 1:

[0052] Table 1 Experimental conditions and results in Examples 1 - 8

[0053]

[0054]

[0055] It can be seen from Table 1 that under the same experimental conditions, the quality of the ferulic acid arginine complex salt prepared with different membrane types is different because ferulate ions and arginine ions will leak into the salt chamber, thus affecting the product quality. The fluxes of ferulate ions and arginine ions are as Figure 2 and Figure 3 shown. The leakage of organic acid ions is related to the types of anion and cation membranes and the feed concentration.

[0056] The foregoing description of the disclosed embodiments enables those skilled in the art to practice or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing arginine ferulate composite salt by self-desalting bipolar membrane electrodialysis, characterized in that: The method for preparing arginine ferulic acid composite salt adopts a bipolar membrane electrodialysis device, wherein the bipolar membrane electrodialysis device comprises an anode plate, a cathode plate and a membrane stack disposed between the anode plate and the cathode plate, wherein the membrane stack is formed by connecting n groups of electrodialysis units in series, and the device is arranged in the following order from the anode to the cathode: anode-anode chamber-[bipolar membrane-acid chamber-cation exchange membrane-salt chamber-anion exchange membrane-alkali chamber]n-bipolar membrane-cathode chamber; The method for preparing arginine ferulate composite salt comprises the following steps: S1, add the alcohol aqueous solution of sodium ferulate to the acid chamber, add the sodium chloride solution to the salt chamber, add the L-Arg hydrochloride solution to the base chamber, and add the sodium sulfate solution to the anode chamber and the cathode chamber; S2, adjusting the temperature of the solution in each chamber to a constant temperature, and starting the self-circulation of each chamber; S3, applying direct current between the anode plate and the cathode plate to perform electrodialysis; S4. When the conductivity of the alkali chamber drops to 1.5±1 mS / cm, the power is turned off, and then the acid chamber feed liquid and the alkali chamber feed liquid are evenly mixed to obtain arginine ferulic acid composite salt.

2. The method according to claim 1, characterized in that The alcohol aqueous solution is n-propanol-water, and the volume ratio of alcohol to water in the alcohol aqueous solution is 50:

50.

3. The method according to claim 1, characterized in that The concentration of the alcohol aqueous solution of sodium ferulate in the acid chamber is 0.1-0.5 mol / L.

4. The method according to claim 1, characterized in that: The concentration of the sodium chloride solution in the salt chamber is 0.1 mol / L.

5. The method according to claim 1, characterized in that The concentration of the L-Arg hydrochloride solution in the alkali chamber is 0.1-0.5 mol / L; the concentration of the sodium sulfate solution is 0.1-0.6 mol / L.

6. The method according to claim 1, characterized in that The temperature of the solution in each chamber is adjusted to 30±1~40±1℃, and the linear velocity of the solution flow is adjusted to 1~10cm / s.

7. The method according to claim 1, characterized in that: The cation exchange membrane used in the membrane stack is CGU, CIMS or C1S; the anion exchange membrane used in the membrane stack is AGU, ACS or A1R.

8. The method according to claim 1, characterized in that The bipolar membrane electrodialysis device operates in a constant voltage mode with an operating voltage of 1-4V per group of electrodialysis units.

9. The method according to claim 1, characterized in that: The value of n is 1-1000.

10. The method according to claim 1, characterized in that It also includes liquid storage tanks and circulation pumps corresponding to the anode chamber, cathode chamber, acid chamber, salt chamber, and alkali chamber respectively; a constant temperature heating device is provided at the bottom of each liquid storage tank; the anode chamber, cathode chamber, acid chamber, salt chamber, and alkali chamber are all provided with a feed inlet and a discharge port, and each chamber is connected to the corresponding liquid storage tank through a pipeline, and uses its own circulation pump as power to form a self-circulating loop.

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