A method for separating lithium and sodium

Abstract

The present application relates to the technical field of ion separation and extraction, and particularly relates to a lithium-sodium separation method.A lithium-sodium separation method comprises the following steps: S1, adding electrode liquid into an anode chamber and a cathode chamber of a bipolar membrane separation device; S2, adding an adsorbent into a first salt chamber of the bipolar membrane separation device, and adding water into a second salt chamber of the bipolar membrane separation device; S3, adding a mixed solution containing lithium ions and sodium ions into the first salt chamber and staying for a period of time; S4, collecting a solution in the first salt chamber; S5, injecting a solution containing lithium ions into the first salt chamber; S6, electrifying the bipolar membrane separation device; and S7, collecting a solution in the second salt chamber; the lithium-sodium separation method can realize continuous separation of lithium and sodium, and the recovery rate of lithium ions can reach about 90%. The method is mature, simple and easy to realize, can effectively remove sodium ions in a lithium product, and improves the purity and quality of the lithium product.

Description

Technical Field

[0001] This invention relates to the field of ion separation and extraction technology, specifically to a method for separating lithium and sodium. Background Technology

[0002] Currently, there are various methods for lithium extraction from salt lakes. Among them, nanofiltration has been widely used in the extraction of lithium resources from salt lakes due to its advantages such as good separation effect of monovalent and divalent ions, high recovery rate, and environmental friendliness. Nanofiltration ultimately yields a mixed solution of lithium and sodium ions, as both lithium and sodium ions are monovalent, and nanofiltration can only separate monovalent and divalent ions. Furthermore, many other lithium extraction methods also produce products with mixed ion valence states. Given the increasing demand for pure lithium products, it is necessary to separate sodium ions. Since lithium and sodium are elements in the same group, have similar chemical properties, and are both relatively light, traditional methods are difficult to use for separation. Chinese invention patent CN108517421A proposes a method for separating lithium and sodium. This method requires acid-base treatment, followed by ion exchange resin, and finally desorption of the adsorbent. This method is relatively cumbersome and is more suitable for systems with high lithium content. Chinese patents CN111197123A and CN108893605A also involve the separation of lithium and sodium using resin methods. Methods for using bipolar membranes and adsorption aggregates that are easier to operate have not yet been addressed.

[0003] Therefore, providing a simple method for separating lithium and sodium is currently the main technical problem that needs to be solved. Summary of the Invention

[0004] To address the aforementioned problems, this invention proposes a lithium-sodium separation method that can effectively separate lithium and sodium from solutions containing lithium and sodium, resulting in a purer lithium product.

[0005] This invention provides a method for separating lithium and sodium, comprising the following steps: S1. Add the electrode solution to the anode and cathode chambers of the bipolar membrane separation device; S2. Add the adsorbent to the first salt chamber of the bipolar membrane separation device, and add water to the second salt chamber of the bipolar membrane separation device; S3. Add the mixture containing lithium ions and sodium ions into the first salt chamber and let it stand for a period of time; S4. Collect the solution from the first salt chamber; S5. Inject a solution containing lithium ions into the first salt chamber; S6. Power on the bipolar membrane separation equipment; S7. Collect the solution in the second salt chamber.

[0006] Preferably, the adsorbent is selected from one or more combinations of zeolite, titanium-based ion sieve, manganese-based ion sieve, and aluminate-based ion sieve.

[0007] Preferably, as an feasible option, the titanium-based ion sieve can be a Li2TiO3 type ion sieve, and the Li2TiO3 type ion sieve is purchased from Shanghai E. En Chemical Technology Co., Ltd.

[0008] Preferably, as an feasible option, the aluminate-based ion sieve can be LiAl. 0.5 Mn 1.5 O4 type ion sieve, the LiAl 0.5 Mn 1.5 The O4 type ion sieve was purchased from Henan Ruisi Environmental Protection Technology Co., Ltd.

[0009] Preferably, the manganese-based ion sieve is an feasible option. The manganese-based ion sieve can be a LiMn2O4 type ion sieve, which is purchased from Wuxi Jingshi New Energy Co., Ltd., and the model is MSL-30 series.

[0010] Preferably, the mixture containing lithium and sodium includes an inorganic salt containing lithium ions and an inorganic salt containing sodium ions.

[0011] Preferably, the molar ratio of lithium ions to sodium ions in the lithium-sodium mixture is 1:(1-20).

[0012] Furthermore, the molar ratio of lithium ions to sodium ions in the lithium-sodium mixture is 1:(3-10).

[0013] Preferably, the mixture containing lithium and sodium includes a mixture containing NaCl and LiCl.

[0014] Preferably, the mass concentration of NaCl in the mixture is 1%-4%.

[0015] Preferably, the mass concentration of LiCl in the mixture is 0.1%-3.5%.

[0016] Preferably, the volume ratio of the adsorbent to the mixture is 1:(1.1-3.5).

[0017] Preferably, the dwell time in S3 is 0.05 h to 2 h.

[0018] Preferably, the electrode solution is an aqueous solution comprising one or more of sodium sulfate, sodium chloride, and lithium chloride.

[0019] Preferably, the concentrations of sodium sulfate, sodium chloride, and lithium chloride in the electrode solution are 3%-10%.

[0020] Preferably, the current density used to energize the bipolar membrane separation device in step S6 is 50-400 A / m. 2 .

[0021] Preferably, the current density used to energize the bipolar membrane separation device in step S6 is 100-200 A / m. 2 .

[0022] To achieve a more environmentally friendly separation of lithium and sodium ions without using acids or alkalis, the inventors discovered in experiments that using titanium-based ion sieves, manganese-based ion sieves, and aluminate-based ion sieves as adsorbents to adsorb lithium and sodium mixtures, especially when the volume ratio of adsorbent to mixture is 1:(1.1-3.5) and the molar ratio of lithium ions to sodium ions in the mixture is 1:(1-20), and hydrogen ions are generated by bipolar membrane electrolysis of water, the adsorbent desorbs the adsorbed lithium ions. When the bipolar membrane separation device is powered on and a current of 50-400 A / m² is applied, under the action of an electric field, the desorbed lithium ions pass through the cathode membrane into the second salt chamber, thus achieving the separation of sodium and lithium ions in the mixture.

[0023] Preferably, the bipolar membrane separation device includes a cathode chamber, an anode chamber, a first salt chamber, and a second salt chamber.

[0024] Preferably, in step S5, a solution containing lithium ions is injected into the first salt chamber; preferably, a solution containing LiCl is injected into the first salt chamber; preferably, the mass concentration of LiCl in the solution is 1%-2%.

[0025] Preferably, a bipolar membrane is disposed in the portion of the first salt chamber separated from the anode chamber, and a cation exchange membrane is disposed in the portion of the first salt chamber separated from the second salt chamber.

[0026] Preferably, an anion exchange membrane is disposed in the portion of the second salt chamber that is separated from the cathode chamber.

[0027] As an feasible option, the bipolar membrane can be a bipolar membrane (BP-2) or a bipolar membrane (ASTOM, BP-1E).

[0028] The bipolar membrane (BP-2) was purchased from Hangzhou Lanran Technology Co., Ltd., and its model is bipolar membrane BP-2.

[0029] The bipolar membrane (ASTOM, BP-1E) was purchased from ASTOM Corporation of Japan, and its model number is BP-1E.

[0030] The separation method of this invention specifies the use of bipolar membranes (BP-2) or (ASTOM, BP-1E), which can reduce the hydrolysis voltage and consume less energy. The water in the first salt chamber is electrolyzed to produce hydrogen ions, and the generated hydrogen ions can interact with the adsorbent to desorb lithium ions.

[0031] The anion exchange membrane was purchased from Hangzhou Lanran Technology Co., Ltd., and its model number is ATD.

[0032] The cation exchange membrane was purchased from Hangzhou Lanran Technology Co., Ltd., and its model number is CT-4.

[0033] To achieve continuous separation of lithium and sodium, effectively separating lithium and sodium from lithium-containing solutions, purifying lithium products, and improving their quality, the inventors discovered that by adding a mixed solution to a bipolar membrane separation device, which includes a cathode chamber, an anode chamber, a first salt chamber, and a second salt chamber, a bipolar membrane is installed between the first salt chamber and the anode chamber, a cation exchange membrane is installed between the first and second salt chambers, and an anion exchange membrane is installed between the second salt chamber and the cathode chamber. Electrode solutions with a concentration of 3%-10% are injected into the cathode and anode chambers respectively. After adsorption of the mixed solution by adding adsorbent from the first salt chamber, the solution in the first salt chamber is collected using a cyclic collection method. This allows for timely separation of the mixed solution that does not contain lithium ions. Upon energization, a lithium ion desorption process is initiated. After separation, the process repeats for the next cycle, thus achieving continuous separation of sodium and lithium ions in the mixed solution.

[0034] Beneficial effects 1. The method of the present invention does not use additional acids or alkalis, making it more environmentally friendly and resource-saving, and it is easy to operate.

[0035] 2. The method of this invention can achieve continuous separation of lithium and sodium, effectively separating lithium and sodium from lithium- and sodium-containing solutions, thereby purifying lithium products and improving their quality. 3. By limiting the type of bipolar membrane used in the separation method of this invention, the hydrolysis voltage can be reduced and the energy consumption is low. Hydrogen ions are electrolyzed from the water in the first salt chamber. The generated hydrogen ions can interact with the adsorbent to release lithium ions, making the separation method more environmentally friendly.

[0036] 4. By adopting the method of the present invention, cyclic separation and continuous separation can be achieved, reducing the complexity of separation methods. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of a bipolar membrane separation device.

[0038] In the diagram: 1. Anode plate, 2. Cathode plate, 3. Anode chamber, 4. First salt chamber, 5. Adsorbent, 6. Second salt chamber, 7. Cathode chamber. Detailed Implementation

[0039] Example 1 This embodiment provides a method for separating lithium and sodium, including the following steps: S1. Add the electrode solution to the anode chamber 3 and cathode chamber 7 of the bipolar membrane separation device; S2. Add the adsorbent to the first salt chamber 4 of the bipolar membrane separation device, and add water to the second salt chamber 6 of the bipolar membrane separation device; S3. Add the mixture containing lithium ions and sodium ions into the first salt chamber and let it stand for 50 minutes; S4. Collect the solution containing sodium ions in the first salt chamber 4; S5. Inject a solution containing lithium ions into the first salt chamber 4; S6. Power on the bipolar membrane separation equipment; S7. Measure the pH value of the solution in the second salt chamber 6. Stop the experiment when the pH value decreases and collect the lithium-containing solution in the second salt chamber 6.

[0040] Figure 1 A schematic diagram of a bipolar membrane separation device is provided.

[0041] The electrode solution is a 3% sodium sulfate solution, and 3L of the 3% sodium sulfate solution is added to both the anode chamber and the anolyte chamber.

[0042] The adsorbent in S2 is a titanium-based ion sieve, and the amount of adsorbent added is 2L.

[0043] The amount of water added in S2 is 1L.

[0044] The titanium-based ion sieve is a Li2TiO3 type ion sieve, and the manufacturer of the Li2TiO3 type ion sieve is Shanghai Yi'en Chemical Technology Co., Ltd.

[0045] The lithium and sodium mixture in S3 is a mixture of NaCl and LiCl. 2 L of the mixture is added to the first salt chamber 4 and left to stand. The molar ratio of lithium ions to sodium ions in the mixture is 3:1.

[0046] The mass concentration of NaCl in the mixture is 1.1%. The mass concentration of LiCl in the mixture is 2.9%.

[0047] In step S5, 2 L of a lithium chloride solution with a mass concentration of 2% is injected into the first salt chamber 4.

[0048] The current density for energizing the bipolar membrane separation device in S6 is 100 A / m. 2 .

[0049] The bipolar membrane separation device includes a cathode chamber 7, an anode chamber 3, a first salt chamber 4, and a second salt chamber 6.

[0050] A bipolar membrane is provided at the portion where the first salt chamber 4 is connected to the anode chamber 3, and a cation exchange membrane is provided at the portion where the first salt chamber 4 is connected to the second salt chamber 6; an anion exchange membrane is provided at the portion where the second salt chamber 6 is connected to the cathode chamber 7.

[0051] The bipolar membrane is a bipolar membrane (BP-2), which was purchased from Hangzhou Lanran Technology Co., Ltd., and its model is bipolar membrane BP-2.

[0052] The anion exchange membrane was purchased from Hangzhou Lanran Technology Co., Ltd., and its model number is ATD.

[0053] The cation exchange membrane was purchased from Hangzhou Lanran Technology Co., Ltd., and its model number is CT-4.

[0054] The lithium-containing solution collected in the second salt chamber 6 was tested using an ICP detection device to determine the lithium ion recovery rate of 80%.

[0055] Example 2 This embodiment provides a method for separating lithium and sodium, including the following steps: S1. Add the electrode solution to the anode chamber 3 and cathode chamber 7 of the bipolar membrane separation device; S2. Add the adsorbent to the first salt chamber 4 of the bipolar membrane separation device, and add water to the second salt chamber 6 of the bipolar membrane separation device; S3. Add the mixture containing lithium ions and sodium ions into the first salt chamber and let it stand for 30 minutes; S4. Collect the solution containing sodium ions in the first salt chamber 4; S5. Inject a solution containing lithium ions into the first salt chamber 4; S6. Power on the bipolar membrane separation equipment; S7. Measure the pH value of the solution in the second salt chamber 6. Stop the experiment when the pH value decreases and collect the lithium-containing solution in the second salt chamber 6.

[0056] The electrode solution is a 5% sodium sulfate solution, and 3L of the 5% sodium sulfate solution is added to both the anode chamber and the ion chamber.

[0057] The amount of water added in S2 is 2L.

[0058] The adsorbent in S2 is a titanium-based ion sieve, and the amount of adsorbent added is 1.5L.

[0059] The titanium-based ion sieve is a Li2TiO3 type ion sieve, and the manufacturer of the Li2TiO3 type ion sieve is Shanghai Yi'en Chemical Technology Co., Ltd.

[0060] The lithium and sodium mixture in S3 is a mixture of NaCl and LiCl. 2.5 L of the mixture is added to the first salt chamber 4 and left to stand. The molar ratio of lithium ions to sodium ions in the mixture is 1:2.

[0061] The mass concentration of NaCl in the mixture is 2.2%. The mass concentration of LiCl in the mixture is 1%.

[0062] In step S5, 2 L of a lithium chloride solution with a mass concentration of 1.5% is injected into the first salt chamber 4.

[0063] The current density for energizing the bipolar membrane separation device in S6 is 150 A / m. 2 .

[0064] The bipolar membrane separation device includes a cathode chamber 7, an anode chamber 3, a first salt chamber 4, and a second salt chamber 6.

[0065] A bipolar membrane is provided at the portion where the first salt chamber 4 is connected to the anode chamber 3, and a cation exchange membrane is provided at the portion where the first salt chamber 4 is connected to the second salt chamber 6; an anion exchange membrane is provided at the portion where the second salt chamber 6 is connected to the cathode chamber 7.

[0066] The bipolar membrane is a bipolar membrane (BP-2), which was purchased from Hangzhou Lanran Technology Co., Ltd., and its model is bipolar membrane BP-2.

[0067] The anion exchange membrane was purchased from Hangzhou Lanran Technology Co., Ltd., and its model number is ATD.

[0068] The cation exchange membrane was purchased from Hangzhou Lanran Technology Co., Ltd., and its model number is CT-4.

[0069] The lithium-containing solution collected in the second salt chamber 6 was tested using an ICP detection device to determine the lithium ion recovery rate of 90%.

[0070] Example 3 This embodiment provides a method for separating lithium and sodium, including the following steps: S1. Add the electrode solution to the anode chamber 3 and cathode chamber 7 of the bipolar membrane separation device; S2. Add the adsorbent to the first salt chamber 4 of the bipolar membrane separation device, and add water to the second salt chamber 6 of the bipolar membrane separation device; S3. Add the mixture containing lithium ions and sodium ions into the first salt chamber and let it stand for 20 minutes; S4. Collect the solution containing sodium ions in the first salt chamber 4; S5. Inject a solution containing lithium ions into the first salt chamber 4; S6. Power on the bipolar membrane separation equipment; S7. Measure the pH value of the solution in the second salt chamber 6. Stop the experiment when the pH value decreases and collect the lithium-containing solution in the second salt chamber 6.

[0071] The electrode solution is a 3% sodium sulfate solution, and 3L of the 3% sodium sulfate solution is added to both the anode chamber and the anolyte chamber.

[0072] The adsorbent in S2 is a titanium-based ion sieve, and the amount of adsorbent added is 1L.

[0073] The amount of water added in S2 is 1L.

[0074] The titanium-based ion sieve is a Li2TiO3 type ion sieve, and the manufacturer of the Li2TiO3 type ion sieve is Shanghai Yi'en Chemical Technology Co., Ltd.

[0075] The lithium and sodium mixture in S3 is a mixture of NaCl and LiCl. 3 L of the mixture is added to the first salt chamber 4 and left to stand. The molar ratio of lithium ions to sodium ions in the mixture is 1:3.

[0076] The mass concentration of NaCl in the mixture is 3.2%. The mass concentration of LiCl in the mixture is 0.8%.

[0077] In step S5, 2 L of a lithium chloride solution with a mass concentration of 1% is injected into the first salt chamber 4.

[0078] The current density for energizing the bipolar membrane separation device in S6 is 100 A / m. 2 .

[0079] The bipolar membrane separation device includes a cathode chamber 7, an anode chamber 3, a first salt chamber 4, and a second salt chamber 6.

[0080] A bipolar membrane is provided at the portion where the first salt chamber 4 is connected to the anode chamber 3, and a cation exchange membrane is provided at the portion where the first salt chamber 4 is connected to the second salt chamber 6; an anion exchange membrane is provided at the portion where the second salt chamber 6 is connected to the cathode chamber 7.

[0081] The bipolar membrane is a bipolar membrane (BP-2), which was purchased from Hangzhou Lanran Technology Co., Ltd., and its model is bipolar membrane BP-2.

[0082] The anion exchange membrane was purchased from Hangzhou Lanran Technology Co., Ltd., and its model number is ATD.

[0083] The cation exchange membrane was purchased from Hangzhou Lanran Technology Co., Ltd., and its model number is CT-4.

[0084] The lithium-containing solution collected in the second salt chamber 6 was tested using an ICP detection device to determine the lithium ion recovery rate, which was found to be 92%.

[0085] Example 4 This embodiment provides a method for separating lithium and sodium, including the following steps: S1. Add the electrode solution to the anode chamber 3 and cathode chamber 7 of the bipolar membrane separation device; S2. Add the adsorbent to the first salt chamber 4 of the bipolar membrane separation device, and add water to the second salt chamber 6 of the bipolar membrane separation device; S3. Add the mixture containing lithium ions and sodium ions into the first salt chamber and let it stand for 20 minutes; S4. Collect the solution containing sodium ions in the first salt chamber 4; S5. Inject a solution containing lithium ions into the first salt chamber 4; S6. Power on the bipolar membrane separation equipment; S7. Measure the pH value of the solution in the second salt chamber 6. Stop the experiment when the pH value decreases and collect the lithium-containing solution in the second salt chamber 6.

[0086] The electrode solution is a 3% sodium sulfate solution, and 3L of the 3% sodium sulfate solution is added to both the anode chamber and the anolyte chamber.

[0087] The amount of water added in S2 is 1L.

[0088] The adsorbent in S2 is an aluminate-based ion sieve, and the amount of the adsorbent added is 1.5L.

[0089] The aluminate-based ion sieve is LiAl 0.5 Mn 1.5 O4 type ion sieve, the LiAl 0.5 Mn 1.5 The O4 type ion sieve was purchased from Henan Ruisi Environmental Protection Technology Co., Ltd.

[0090] The lithium and sodium mixture in S3 is a mixture of NaCl and LiCl. 3 L of the mixture is added to the first salt chamber 4 and left to stand. The molar ratio of lithium ions to sodium ions in the mixture is 1:5.

[0091] The mass concentration of NaCl in the mixture is 3.5%. The mass concentration of LiCl in the mixture is 0.5%.

[0092] In step S5, 1.5 L of a lithium chloride solution with a mass concentration of 1% is injected into the first salt chamber 4.

[0093] The current density for energizing the bipolar membrane separation device in S6 is 100 A / m. 2 .

[0094] The bipolar membrane separation device includes a cathode chamber 7, an anode chamber 3, a first salt chamber 4, and a second salt chamber 6.

[0095] A bipolar membrane is provided at the portion where the first salt chamber 4 is connected to the anode chamber 3, and a cation exchange membrane is provided at the portion where the first salt chamber 4 is connected to the second salt chamber 6; an anion exchange membrane is provided at the portion where the second salt chamber 6 is connected to the cathode chamber 7.

[0096] The bipolar membrane is an ASTOM (BP-1E) bipolar membrane, which was purchased from ASTOM Corporation of Japan, and its model is BP-1E.

[0097] The anion exchange membrane was purchased from Hangzhou Lanran Technology Co., Ltd., and its model number is ATD.

[0098] The cation exchange membrane was purchased from Hangzhou Lanran Technology Co., Ltd., and its model number is CT-4.

[0099] The lithium-containing solution collected in the second salt chamber 6 was tested using an ICP detection device to determine the lithium ion recovery rate, which was found to be 93%.

[0100] Example 5 This embodiment provides a method for separating lithium and sodium, including the following steps: S1. Add the electrode solution to the anode chamber 3 and cathode chamber 7 of the bipolar membrane separation device; S2. Add the adsorbent to the first salt chamber 4 of the bipolar membrane separation device, and add water to the second salt chamber 6 of the bipolar membrane separation device; S3. Add the mixture containing lithium ions and sodium ions into the first salt chamber and let it stand for 35 minutes; S4. Collect the solution containing sodium ions in the first salt chamber 4; S5. Inject a solution containing lithium ions into the first salt chamber 4; S6. Power on the bipolar membrane separation equipment; S7. Measure the pH value of the solution in the second salt chamber 6. Stop the experiment when the pH value decreases and collect the lithium-containing solution in the second salt chamber 6.

[0101] The electrode solution is a 5% sodium sulfate solution, and 3L of the 5% sodium sulfate solution is added to both the anode chamber and the ion chamber.

[0102] The amount of water added in S2 is 1L.

[0103] The adsorbent in S2 is a manganese-based ion sieve, and the amount of adsorbent added is 2L.

[0104] The manganese-based ion sieve is a LiMn2O4 type ion sieve, which was purchased from Wuxi Jingshi New Energy Co., Ltd., and the model is MSL-30 series.

[0105] The lithium and sodium mixture in S3 is a mixture of NaCl and LiCl. 2.5 L of the mixture is added to the first salt chamber 4 and left to stand. The molar ratio of lithium ions to sodium ions in the mixture is 1:1.

[0106] The mass concentration of NaCl in the mixture is 2.4%. The mass concentration of LiCl in the mixture is 1.6%.

[0107] In step S5, 2.5 L of a lithium chloride solution with a mass concentration of 1.5% is injected into the first salt chamber 4.

[0108] The current density for energizing the bipolar membrane separation device in S6 is 150 A / m. 2 .

[0109] The bipolar membrane separation device includes a cathode chamber 7, an anode chamber 3, a first salt chamber 4, and a second salt chamber 6.

[0110] A bipolar membrane is provided at the portion where the first salt chamber 4 is connected to the anode chamber 3, and a cation exchange membrane is provided at the portion where the first salt chamber 4 is connected to the second salt chamber 6; an anion exchange membrane is provided at the portion where the second salt chamber 6 is connected to the cathode chamber 7.

[0111] The bipolar membrane is an ASTOM (BP-1E) bipolar membrane, which was purchased from ASTOM Corporation of Japan, and its model is BP-1E.

[0112] The anion exchange membrane was purchased from Hangzhou Lanran Technology Co., Ltd., and its model number is ATD.

[0113] The cation exchange membrane was purchased from Hangzhou Lanran Technology Co., Ltd., and its model number is CT-4.

[0114] The lithium-containing solution collected in the second salt chamber 6 was tested using an ICP detection device to determine the lithium ion recovery rate, which was 87%.

[0115] Example 6 This embodiment provides a method for separating lithium and sodium, including the following steps: S1. Add the electrode solution to the anode chamber 3 and cathode chamber 7 of the bipolar membrane separation device; S2. Add the adsorbent to the first salt chamber 4 of the bipolar membrane separation device, and add water to the second salt chamber 6 of the bipolar membrane separation device; S3. Add the mixture containing lithium ions and sodium ions into the first salt chamber and let it stand for 15 minutes; S4. Collect the solution containing sodium ions in the first salt chamber 4; S5. Inject a solution containing lithium ions into the first salt chamber 4; S6. Power on the bipolar membrane separation equipment; S7. Measure the pH value of the solution in the second salt chamber 6. Stop the experiment when the pH value decreases and collect the lithium-containing solution in the second salt chamber 6.

[0116] The electrode solution is a 5% sodium sulfate solution, and 3L of the 5% sodium sulfate solution is added to both the anode chamber and the ion chamber.

[0117] The amount of water added in S2 is 1L.

[0118] The adsorbent in S2 is a manganese-based ion sieve, and the amount of adsorbent added is 1L.

[0119] The manganese-based ion sieve is a LiMn2O4 type ion sieve, which was purchased from Wuxi Jingshi New Energy Co., Ltd., and the model is MSL-30 series.

[0120] The lithium and sodium mixture in S3 is a mixture of NaCl and LiCl. 3L of the mixture is added to the first salt chamber 4 and left to stand. The molar ratio of lithium ions to sodium ions in the mixture is 1:9.

[0121] The mass concentration of NaCl in the mixture is 3.7%. The mass concentration of LiCl in the mixture is 0.3%.

[0122] In step S5, 2L of a lithium chloride solution with a mass concentration of % is injected into the first salt chamber 4.

[0123] The current density for energizing the bipolar membrane separation device in S6 is 200 A / m. 2 .

[0124] The bipolar membrane separation device includes a cathode chamber 7, an anode chamber 3, a first salt chamber 4, and a second salt chamber 6.

[0125] A bipolar membrane is provided at the portion where the first salt chamber 4 is connected to the anode chamber 3, and a cation exchange membrane is provided at the portion where the first salt chamber 4 is connected to the second salt chamber 6; an anion exchange membrane is provided at the portion where the second salt chamber 6 is connected to the cathode chamber 7.

[0126] The bipolar membrane is an ASTOM (BP-1E) bipolar membrane, which was purchased from ASTOM Corporation of Japan, and its model is BP-1E.

[0127] The anion exchange membrane was purchased from Hangzhou Lanran Technology Co., Ltd., and its model number is ATD.

[0128] The cation exchange membrane was purchased from Hangzhou Lanran Technology Co., Ltd., and its model number is CT-4.

[0129] The lithium-containing solution collected in the second salt chamber 6 was tested using an ICP detection device to determine the lithium ion recovery rate of 90%.

Claims

1. A method for separating lithium and sodium, characterized in that, Includes the following steps: S1. Add the electrode solution to the anode and cathode chambers of the bipolar membrane separation device; S2. Add the adsorbent to the first salt chamber of the bipolar membrane separation device, and add water to the second salt chamber of the bipolar membrane separation device; S3. Add the mixture containing lithium ions and sodium ions into the first salt chamber and let it stand for a period of time; S4. Collect the solution in the first salt chamber; S5. Inject a solution containing lithium ions into the first salt chamber; S6. Power on the bipolar membrane separation equipment; S7. Collect the solution in the second salt chamber; The adsorbent is selected from one or more combinations of zeolite, titanium ion sieve, manganese ion sieve and aluminate ion sieve. The molar ratio of lithium ions to sodium ions in the mixture is 1:(1-20); the volume ratio of the adsorbent to the mixture is 1:(1.1-3.5). The current density for energizing the bipolar membrane separation device in step S6 is 50-400 A / m. 2 ; The bipolar membrane separation device includes a cathode chamber, an anode chamber, a first salt chamber, and a second salt chamber; a bipolar membrane is disposed in the portion of the first salt chamber separated from the anode chamber, and a cation exchange membrane is disposed in the portion of the first salt chamber separated from the second salt chamber.

2. The lithium and sodium separation method as described in claim 1, characterized in that, The molar ratio of lithium ions to sodium ions in the mixture is 1:(3-10).

3. The lithium and sodium separation method according to any one of claims 1-2, characterized in that, The dwell time in S3 is 0.05 h to 2 h.

4. The lithium and sodium separation method as described in claim 1, characterized in that, The electrode solution is an aqueous solution of one or more of sodium sulfate, sodium chloride, and lithium chloride.

5. The lithium and sodium separation method as described in claim 4, characterized in that, The concentration of the electrode solution is 3%-10%.

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