A method for in-situ boron removal from brine and its application

Abstract

This invention discloses a method for in-situ boron removal from brine and its application. The method includes: adding the brine to be treated, a first sodium chloride solution, and a second sodium chloride solution to the acid chamber, salt chamber, and alkali chamber of a bipolar membrane electrodialysis device, respectively; adding an electrode solution to both the anode and cathode chambers; and performing electrodialysis to form boric acid in the acid chamber. This method offers good boron removal efficiency and is environmentally friendly, energy-saving, and economical, making it suitable for applications such as lithium extraction from brine or boron-containing water treatment.

Description

Technical Field

[0001] This invention relates to the field of brine treatment technology, specifically to a method for boron removal from brine and its application. Background Technology

[0002] Brine treatment is involved in numerous industrial applications, such as salt chemical industry, seawater desalination, and electrodialysis water treatment. Brine often contains impurities such as borates, which pose challenges to brine treatment. For example, in the process of lithium extraction via brine electrodialysis, when the boron concentration exceeds a certain range, it can lead to membrane fouling, resulting in poor lithium extraction efficiency and excessively high residual boron content in the lithium-extracted product, causing it to fail to meet quality standards.

[0003] Traditional methods for boron removal from brine mainly include chemical precipitation, membrane separation, and ion exchange. While these methods have some effect on removing boron from brine, they also have limitations. For example, the acid-based chemical precipitation method for salt lake brine not only consumes large amounts of acid chemicals, but also incurs high operating costs due to the long-distance transportation of these chemicals, as salt lakes are generally located in remote areas. Furthermore, the water content in the acid chemicals themselves dilutes the brine (commonly at acid concentrations of 2 mol / L), reducing the effectiveness of boron removal and potentially introducing other groups or impurities such as acid radicals. Membrane separation technology is highly dependent on the chemical composition of the brine, and its boron removal efficiency is overly reliant on the selectivity of the membrane material. Boron in brine typically exists as borate and boric acid molecules. Since boric acid molecules can migrate across the membrane through nanofiltration, the boron removal effect is not ideal. When the brine contains high levels of SO4... 2- When divalent or other high-valence ions are present, the operating pressure of membrane separation becomes high, resulting in significant energy consumption. Ion exchange is generally only suitable for brine with low boron concentrations. When the boron concentration in the brine is high, boron removal using ion exchange requires frequent periodic resin regeneration, making the process complex and time-consuming.

[0004] Therefore, there is a need to develop an efficient and economical method for treating boron-containing brine to meet the needs of industrial production. Summary of the Invention

[0005] This invention aims to at least solve one of the technical problems existing in the prior art. To this end, this invention proposes a method for removing boron from brine that achieves excellent boron removal results without using chemical acids, and is also environmentally friendly, energy-saving, and economical.

[0006] The present invention also provides an application of the above-described method for removing boron from brine.

[0007] Specifically, the first aspect of this invention relates to a method for removing boron from brine, comprising the following steps:

[0008] A first sodium chloride solution, a second sodium chloride solution, an electrode solution, and a bipolar membrane electrodialysis device are provided. The bipolar membrane electrodialysis device includes an anode, a cathode, and a membrane stack arranged between the anode and cathode at intervals. The membrane stack includes at least one membrane unit, which includes an acid chamber, a salt chamber, and an alkali chamber arranged in order of distance from the anode. The acid chamber, salt chamber, and alkali chamber are formed by a first bipolar membrane, an acid-blocking anion exchange membrane, a cation exchange membrane, and a second bipolar membrane arranged in sequence at intervals. If there are multiple membrane units, in two adjacent membrane units, the second bipolar membrane of the membrane unit closer to the anode serves as the first bipolar membrane of the other membrane unit. The anode and the first bipolar membrane of the nearest membrane unit form an anode chamber, and the cathode and the second bipolar membrane of the nearest membrane unit form a cathode chamber. The electrode solution is selected from a first sodium hydroxide solution or a sodium sulfate solution.

[0009] The brine to be treated, the first sodium chloride solution, and the second sodium chloride solution are added to the acid chamber, salt chamber, and alkali chamber, respectively. The electrode liquid is added to both the anode chamber and the cathode chamber for electrodialysis, and boric acid and the second sodium hydroxide solution are formed in the acid chamber and the alkali chamber, respectively.

[0010] The method for removing boron from brine according to the first aspect of the present invention has at least the following beneficial effects:

[0011] In this bipolar membrane electrodialysis device, an acid chamber is formed between the first bipolar membrane and the acid-blocking anion exchange membrane; a salt chamber is formed between the acid-blocking anion exchange membrane and the cation exchange membrane; and an alkali chamber is formed between the cation exchange membrane and the second bipolar membrane. The cathode and anode chambers are located at opposite ends of the membrane stack. When a reverse voltage is applied to the anode and cathode (anode connected to the positive electrode, cathode connected to the negative electrode), a narrow region of strong electric field appears at the interface layer between the two bipolar membranes (i.e., the first bipolar membrane and the second bipolar membrane, abbreviated as BP). At this time, water molecules rapidly dissociate to generate H+. + and OH - The water molecules migrate to the acid and base chambers respectively, and the consumed water molecules are replenished from the external solution to the intermediate interface layer through diffusion. H+ migrates to the acid chamber. + With boron anions (B(OH)4) in the brine - In situ, they combine to form boric acid, which readily precipitates out, thus achieving in-situ removal of boron from the brine; OH- migrating to the alkali chamber reacts with Na+ that has passed through the cation exchange membrane. + They combine to form sodium hydroxide.

[0012] Acid-resistant anion exchange membranes (e.g., anion exchange membranes modified with weakly basic exchange groups (e.g., tertiary amine groups)) are effective against H+. + Strong barrier properties ensure the H+ in the acid chamber +Concentration can improve boron removal efficiency. Adding brine to the acid chamber allows for in-situ generation of boric acid, achieving efficient removal of boron from the brine. Adding sodium chloride solution to the salt and alkali chambers, and sodium hydroxide or sodium sulfate solution to the electrode chambers (cathode / anode chambers), ensures efficient boric acid generation while minimizing interpenetration between solutions, resulting in low brine expansion and minimal impact on other brine components.

[0013] Electrodialysis utilizes an electric field to dissociate water molecules, achieving brine acidification and in-situ boron removal. This avoids the negative effects of adding chemicals for boron removal, such as excessive dilution of the brine. This method offers excellent boron removal efficiency, is less affected by the chemical composition of boron-containing brine, and boasts advantages such as simple operation, low energy consumption, and no secondary pollution, thus achieving efficient, environmentally friendly, energy-saving, and economical treatment.

[0014] According to some embodiments of the present invention, the concentrations of the first sodium chloride solution and the second sodium chloride solution are independently 1.5–2.5 mol / L, specifically 1.5 mol / L, 1.8 mol / L, 2 mol / L, 2.2 mol / L, 2.5 mol / L, or any value between the two. That is, the specific salt concentration is not limited to the listed values, and other unlisted values ​​within the range are also applicable. At this salt concentration, a certain conductivity can be ensured to promote boric acid formation and water electrolysis, thereby improving the boron removal effect, while avoiding excessively high concentrations that could lead to osmosis and affect the brine composition.

[0015] According to some embodiments of the present invention, the concentrations of the first sodium chloride solution and the second sodium chloride solution are independently 2 to 2.5 mol / L.

[0016] According to some embodiments of the present invention, the first sodium chloride solution and the second sodium chloride solution have the same concentration.

[0017] According to some embodiments of the present invention, the polar liquid is selected from a first sodium hydroxide solution.

[0018] According to some embodiments of the present invention, the mass concentration of the first sodium hydroxide solution is 3% to 4%. The sodium hydroxide solution in the anode and cathode chambers plays a role in promoting ion circulation. During electrodialysis, the sodium hydroxide solution essentially does not decrease or increase, so it does not need to be replenished.

[0019] According to some embodiments of the present invention, the brine to be treated is old brine from a salt lake. Old brine from a salt lake refers to the concentrated solution remaining after the extraction of salt minerals from a salt lake. Old brine contains a variety of minerals and chemical components, mainly including sodium, potassium, magnesium, lithium, boron, calcium, and other ions.

[0020] According to some embodiments of the present invention, the voltage applied during electrodialysis is a constant voltage.

[0021] According to some embodiments of the present invention, in the electrodialysis, the voltage applied to a single membrane module unit is 1.9 to 2.5V, for example, it can be 1.9V, 2V, 2.3V, 2.5V, or any value between the two. This voltage range is beneficial for water electrolysis, while excessively high voltage may cause bipolar membrane polarization.

[0022] According to some embodiments of the present invention, in the electrodialysis, the voltage applied to a single membrane module unit is 1.9 to 2.1 V.

[0023] According to some embodiments of the present invention, the pH of the brine electrodialyzed into the acid chamber is maintained at 1-3. The brine pH is generally close to neutral, requiring further introduction of H₂. + This promotes the formation of boric acid. As the pH value of the acid chamber brine decreases, the effect of in-situ boron removal by electrodialysis becomes better and better, and the volume ratio of the brine before and after treatment does not change much.

[0024] According to some embodiments of the present invention, the pH of the brine electrodialyzed into the acid chamber is maintained at 1 to 2.

[0025] According to some embodiments of the present invention, during the electrodialysis process, the internal temperature of the membrane stack is maintained at 30-35°C, and a certain feed solution temperature is maintained to reduce the precipitation of boric acid in the membrane stack.

[0026] According to some embodiments of the present invention, the volume ratio of the first sodium chloride solution added to the salt chamber to the second sodium chloride solution added to the alkali chamber is 1:1 to 4:1, for example, it can be 1:1, 2:1, 3:1, 4:1 or any value between the two. Appropriately increasing this volume ratio is beneficial to improving the boron removal effect.

[0027] According to some embodiments of the present invention, the volume ratio of the first sodium chloride solution added to the salt chamber to the second sodium chloride solution added to the alkali chamber is 2:1 to 4:1.

[0028] According to some embodiments of the present invention, the volume of the brine to be treated added to the acid chamber is equal to the volume of the second sodium chloride solution added to the alkali chamber.

[0029] According to some embodiments of the present invention, the volume of the second sodium chloride solution added to the alkali chamber is equal to the volume of the electrode liquid added to at least one of the anode chamber and the cathode chamber. That is, the volume of the added second sodium chloride solution is equal to the volume of the electrode liquid added to the anode chamber or the cathode chamber, and when the volumes of the electrode liquid added to the anode chamber and the cathode chamber are equal, the volumes of the above three solutions are all equal.

[0030] According to some embodiments of the present invention, an equal volume of a first sodium hydroxide solution is added to the anode chamber and the cathode chamber.

[0031] According to some embodiments of the present invention, the first sodium chloride solution and the second sodium chloride solution may use sodium chloride produced from salt lakes to save costs.

[0032] According to some embodiments of the present invention, a collection container is used to collect the feed solution in the acid chamber after electrodialysis. Specifically, the temperature of the feed solution inside the membrane stack can be controlled, for example, by maintaining the temperature of the feed solution inside the membrane stack at 30-35°C, to reduce the precipitation of boric acid in the acid chamber. After electrodialysis, the feed solution in the acid chamber is transferred to the collection container, and boric acid is precipitated in the collection container by means of cooling or other measures, thereby reducing the fouling of the electrodialysis membrane.

[0033] According to some embodiments of the present invention, the number of membrane modules is 1 to 50, for example, it can be 1, 5, 10, 20, 30, 40, or any value between any two. It is understood that when there are multiple membrane modules, adjacent membrane modules share a single bipolar membrane. This can be understood as the second bipolar membrane of the membrane module closer to the anode serving as the first bipolar membrane of the other membrane module. Under the same conditions, increasing the number of membrane modules is beneficial for increasing the brine treatment capacity.

[0034] According to some embodiments of the present invention, the number of membrane units is 5 to 40.

[0035] According to some embodiments of the present invention, the electrodialysis is continuous or intermittent.

[0036] According to some embodiments of the present invention, the brine to be treated is subjected to electrodialysis once or multiple times. Multiple times can be performed intermittently or continuously in cycles, which can further improve the boron removal rate.

[0037] According to some embodiments of the present invention, the brine to be treated is further subjected to ultrafiltration to remove impurities. The pore size of the ultrafiltration is, for example, ≤100 nm.

[0038] According to some embodiments of the present invention, the method further includes a step of removing heavy metal ions from the first sodium chloride solution and / or the second sodium chloride solution. Specifically, known ion exchange resins can be used to adsorb and remove heavy metal ions.

[0039] The second aspect of the present invention relates to the application of the above-described method for removing boron from brine in the extraction of lithium from brine or in the treatment of boron-containing water.

[0040] Given that the above method has good boron removal effect and has the advantages of high efficiency, environmental protection, energy saving and economy, it can improve the lithium extraction effect, reduce the residual boron content in lithium products, and at the same time has environmental protection, energy saving and economy.

[0041] In addition, it can be used for boron removal treatment of boron-containing water, such as seawater desalination, which can improve boron removal efficiency, reduce boron removal costs, and ensure environmental friendliness.

[0042] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. Attached Figure Description

[0043] Figure 1 The image shows the XRD pattern of the boric acid precipitate separated from the acid chamber feed solution after electrodialysis in Example 1.

[0044] Figure 2 This is a simplified flow chart of the continuous electrodialysis process in Example 1.

[0045] Figure 3 This is a schematic diagram of the boron removal principle by electrodialysis in Example 1. Detailed Implementation

[0046] The embodiments of the present invention are described in detail below. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0047] In the following examples, the brine is old brine from a salt lake, which has been pre-treated by ultrafiltration to remove impurities. The filter pore size is 100 nm. The composition of the brine after impurity removal is shown in Table 1. The pH of the brine is 6.41.

[0048] Table 1. Main components of the brine after ultrafiltration (g / L)

[0049]

[0050] The selection of membrane stacks and membrane materials is shown in Table 2.

[0051] Table 2. Models and Manufacturers of Membrane Stacks and Membrane Materials

[0052]

[0053] Ion content determination:

[0054] The concentration of Li in the solution was determined using an inductively coupled plasma optical emission spectrometer (ICP-OES, Thermo Scientific iCAP-7200). + Na + K + and Mg 2+ Ca 2+Concentration and B content; H + OH - The concentration was determined by phenolphthalein titration; Cl - Titration was performed using silver nitrate solution.

[0055] Unless otherwise specified, all raw materials or equipment involved are commercially available standard products.

[0056] Example 1

[0057] A method for removing boron from brine:

[0058] (1) The salt chamber, acid chamber, alkali chamber, and electrode chambers (including the anode and cathode chambers) were circulated and cleaned with pure water until the conductivity was 0, and then the feed solution was added. 500 mL of 3 wt% NaOH solution was added to the electrode chambers. 2.1 mol / L sodium chloride solution was added to the salt and alkali chambers, and brine was added to the acid chamber. The volume of each acid / alkali chamber was 500 mL, and the volume of the salt chamber was 1000 mL. The sodium chloride solution was pre-adsorbed with LSC-100 chelating resin (iminodiacetic acid type chelated weakly acidic macroporous cation exchange resin) to remove heavy metals. Then, a circulation pump was connected, and the solution was circulated for 30 min until no bubbles were present.

[0059] (2) Set the voltage and current. Set the current to the maximum value and the voltage to 20V (20V / 10 membranes, i.e., 2V per membrane). Then turn on the power to perform electrodialysis, record the pH value of the brine in the acid chamber, and maintain the feed temperature at 35℃.

[0060] Electrodialysis can be intermittent: When the pH stabilizes at the endpoint of electrodialysis (pH 3), stop the electrodialysis and record the liquid levels in the acid / salt / alkali chambers, as well as the current and voltage. Sampling and testing: Collect the liquid from the acid chamber, cool it to below 20°C, and let it stand overnight (12 hours). Boric acid crystals will precipitate. Perform solid-liquid separation, and after drying the solid, perform phase analysis. XRD pattern is shown below. Figure 1 It can be seen that high-purity boric acid was separated from the brine through electrodialysis.

[0061] Electrodialysis can also be performed using a continuous process, see reference. Figure 2 Brine is pumped into the acid chamber via an acid feed pump, while sodium chloride solution is pumped into the salt and alkali chambers via salt and alkali feed pumps, respectively, for electrodialysis treatment. A diaphragm pump facilitates feed-liquid circulation within the membrane stack. Data is recorded and samples are taken for testing when the brine pH is maintained at 3. The brine discharge from the acid chamber is transferred to a boron-removed old brine collection tank (the discharge volume from the acid chamber is recorded) for boric acid precipitation and solid-liquid separation. Solid phase analysis results are compared with... Figure 2 Similarly, the alkali chamber discharges the material into a brine collection tank. Automatic control of material replenishment or circulation is achieved via a control panel.

[0062] Boron removal principle reference Figure 3(Taking only one membrane unit as an example), when a reverse voltage is applied across the bipolar membrane, a narrow region of strong electric field appears in the middle interface layer of the bipolar membrane (BP). At this time, water molecules rapidly dissociate to generate H+. + and OH - The water molecules migrate to the acid and base chambers respectively, and the consumed water molecules are replenished from the external solution to the intermediate interface layer through diffusion. H+ migrates to the acid chamber... + With boron anions (B(OH)4) in the brine - OH- ions bind in situ and migrate to the alkali chamber. - With Na passing through the cation membrane + The compounds combine to form boric acid and NaOH in the acid chamber and the alkali chamber, respectively.

[0063] Example 2 (Different endpoint pH)

[0064] A method for removing boron from brine is identical to Example 1, except that in step (3), the final pH of the brine at the electrodialysis endpoint is 2 (achieved by extending the electrodialysis time) (taking the intermittent method as an example, the effect of the continuous method is similar).

[0065] Example 3 (Different endpoint pH)

[0066] A method for removing boron from brine is identical to that in Example 1, except that the final pH of the brine at the electrodialysis endpoint (3) is 1.

[0067] Example 4 (Different salt / alkali chamber concentrations)

[0068] A method for removing boron from brine is identical to that in Example 1, except that in step (1), the sodium chloride concentration in both the salt chamber and the alkali chamber is 1.5 mol / L.

[0069] Example 5 (Different types of polar liquid)

[0070] A method for removing boron from brine is identical to that in Example 1, except that in step (1), 500 mL of 3 wt% Na2SO4 is added to the electrode chamber.

[0071] Example 6 (Different Voltages)

[0072] A method for removing boron from brine is identical to that in Example 1, except that step (2) sets the voltage to 25V (25V / 10 membranes, i.e., 2.5V per membrane).

[0073] Comparative Example 1 (Direct addition of acid to remove boron)

[0074] A method for removing boron directly from brine by adding acid includes:

[0075] Take an appropriate amount of brine (same as in Example 1) into a beaker and record the initial volume. Place the beaker in a constant temperature water bath at 25-30℃. Then, slowly add 2 mol / L hydrochloric acid to the brine while monitoring the pH of the brine in real time. When pH = 3, stop adding hydrochloric acid to the brine and record the amount of acid added and the volume of the brine at the end.

[0076] Comparative Example 2 (different vaginal membranes)

[0077] A method for removing boron from brine is the same as in Example 1, except that in step (5), the acid-blocking anion membrane is replaced with a regular anion membrane.

[0078] The boron removal rate and brine expansion rate of each embodiment and comparative example are shown in Tables 3 and 4.

[0079] The boron removal rate is calculated as follows: (Boron content in the brine before treatment - Boron content in the brine after treatment (liquid phase after solid-liquid separation)) * 100% / Boron content in the brine before treatment, where the unit of boron content is g.

[0080] Expansion rate of old brine = (volume of brine after treatment - volume of brine before treatment) * 100% / volume of brine before treatment.

[0081] Table 3 Comparison of In-situ Boron Removal Conditions in Experiments

[0082]

[0083] Table 4 Comparison of boron removal efficiency and expansion rate between in-situ boron removal and acid-based boron removal.

[0084]

[0085] According to Table 3, as shown in Examples 1 and 4, an initial salt concentration of 2.1 mol / L is more effective at removing boron than 1.5 mol / L. This is because a higher salt concentration results in higher conductivity, lower membrane stack resistance, higher current under constant voltage conditions, and faster ion migration, which is beneficial for the formation of boric acid and promotes the dissociation of water by the bipolar membrane to generate H₂. + and OH - This improves boron removal efficiency. As shown in Examples 1 and 5, using NaOH solution as the electrode liquid is more effective than using Na2SO4 solution. This is because, at the same concentration, NaOH solution has a higher conductivity than Na2SO4 solution. Under constant pressure conditions, NaOH solution provides a larger current as the electrode liquid, resulting in a faster ion migration rate inside the membrane stack and a higher H2O generation rate from the bipolar membrane dissociation. + and OH - The more. As seen in Examples 1 and 6, a voltage of 20V is more effective at removing boron than 25V. This is because excessively high voltage can cause polarization of the bipolar film, which is detrimental to the electrolysis of water to generate H₂. + and OH - .

[0086] As can be seen from Example 1 and Comparative Example 2, the boron removal effect of the acid-barrier anion membrane is significantly better than that of the ordinary anion membrane. This is because H + Due to the tunneling effect, leakage can easily occur in the acid chamber. + The concentration is reduced, and using an acid-blocking anion exchange membrane can reduce H+. + The leakage occurred. The slight difference in the expansion rate of the old brine between the two may be related to the difference in permeability caused by the different materials of the ordinary anion membrane and the acid-barrier anion membrane.

[0087] According to Table 4, as shown in Example 1 and Comparative Example 1, when the pH of the acid chamber brine is 3 after electrodialysis, the boron removal rates of in-situ electrodialysis and direct acid addition are similar (the difference in boron removal rates between the two is considered as an error range). However, in terms of the expansion rate of the old brine, in-situ electrodialysis boron removal is only about 1 / 5 of that of direct acid addition boron removal. As shown in Examples 2 and 3, as the pH value of the treated acid chamber brine decreases, the effect of in-situ electrodialysis boron removal becomes better and better, with a boron removal rate as high as 62.61%, and the volume ratio of the brine before and after the treatment does not change much.

[0088] Compared to chemical treatment methods that directly add acid, bipolar membrane electrodialysis technology does not require the introduction of additional acid, avoiding the shortcomings of directly adding chemical acids for boron removal. Furthermore, by adjusting process parameters such as electric field strength, a higher boron removal rate can be achieved, and the process is stable and controllable. This method has excellent boron removal performance and offers advantages in terms of efficiency, environmental friendliness, energy saving, and economy. Consequently, this method can be used in the boron removal process of lithium extraction from salt lake brine, reducing the residual boron content in the lithium product while also offering advantages in environmental protection, energy saving, and economy.

[0089] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A method for removing boron from brines, characterized in that, The method comprises the following steps: Providing a first sodium chloride solution, a second sodium chloride solution, an electrolyte solution and a bipolar membrane electrodialysis device; the bipolar membrane electrodialysis device comprises an anode, a cathode, and a membrane stack arranged between the anode and the cathode; the membrane stack comprises at least one membrane group unit, the membrane group unit comprises an acid chamber, a salt chamber and a base chamber arranged in sequence from the anode to the cathode; the acid chamber, the salt chamber and the base chamber are formed by a first bipolar membrane, an acid-resistant anion exchange membrane, a cation exchange membrane and a second bipolar membrane arranged in sequence; if there are multiple membrane group units, in two adjacent membrane group units, the second bipolar membrane of the membrane group unit close to the anode is used as the first bipolar membrane of the other membrane group unit; the anode and the first bipolar membrane of the closest membrane group unit form an anode chamber, and the cathode and the second bipolar membrane of the closest membrane group unit form a cathode chamber; the electrolyte solution is selected from a first sodium hydroxide solution or a sodium sulfate solution; Adding the brine to be treated, the first sodium chloride solution and the second sodium chloride solution into the acid chamber, the salt chamber and the base chamber respectively, and adding the electrolyte solution into the anode chamber and the cathode chamber, and performing electrodialysis to form boric acid and a second sodium hydroxide solution in the acid chamber and the base chamber respectively.

2. The method of removing boron from brines according to claim 1, characterized in that, The concentration of the first sodium chloride solution and the second sodium chloride solution is independently 1.5-2.5 mol / L.

3. The method of removing boron from brines according to claim 2, wherein, The concentration of the first sodium chloride solution and the second sodium chloride solution is the same.

4. The method of claim 1, wherein, The electrolyte solution is selected from a first sodium hydroxide solution.

5. The method of claim 4, wherein the brine is a sodium chloride solution. The mass concentration of the first sodium hydroxide solution is 3%-4%.

6. The method of removing boron from brines according to claim 1, wherein, The voltage applied in the electrodialysis is a constant voltage.

7. The method of removing boron from brines according to claim 6, wherein, The voltage applied to a single membrane group unit in the electrodialysis is 1.9-2.5 V.

8. The method of removing boron from brines according to claim 1, wherein, The pH of the brine in the acid chamber in the electrodialysis is maintained at 1-3.

9. The method of removing boron from brines according to claim 8, wherein, The internal temperature of the membrane stack is maintained at 30-35°C during the electrodialysis.

10. The method of removing boron from brines according to claim 1, wherein, The volume ratio of the first sodium chloride solution added into the salt chamber to the second sodium chloride solution added into the base chamber is 1:1-4:

1.

11. The method of removing boron from brines according to claim 10, wherein, The volume of the brine to be treated added into the acid chamber is equal to that of the second sodium chloride solution added into the base chamber.

12. The method of removing boron from brines according to claim 10, wherein, The volume of the second sodium chloride solution added into the base chamber is equal to that of the electrolyte solution added into at least one of the anode chamber and the cathode chamber.

13. The method of removing boron from brines according to claim 10, wherein, Equal volumes of the first sodium hydroxide solution are added into the anode chamber and the cathode chamber.

14. The method of removing boron from brines according to claim 1, wherein, The number of the membrane group units is 1-50.

15. The method of removing boron from brines according to claim 1, wherein, The brine to be treated is subjected to electrodialysis once or multiple times.

16. The method of removing boron from brines according to claim 15, wherein, The electrodialysis is continuous or intermittent.

17. The method of removing boron from brines according to claim 1, wherein, The brine to be treated is subjected to ultrafiltration.

18. The method of removing boron from brines according to claim 17, wherein, The first sodium chloride solution and / or the second sodium chloride solution is subjected to a step of removing heavy metal ions.

19. The method for removing boron from brine according to any one of claims 1-18 is applied to lithium extraction from brine or treatment of water containing boron.

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