Composite lithium extraction adsorbent, and preparation method therefor and use thereof

Abstract

Provided in the present disclosure are a composite lithium extraction adsorbent, and a preparation method therefor and the use thereof. The composite lithium extraction adsorbent comprises a lithium extraction adsorbent and a modified oxygen evolution catalyst provided on the surface of the lithium extraction adsorbent, and the modified oxygen evolution catalyst comprises a sulfur-containing NiFe-LDH oxygen evolution catalyst. In the present disclosure, the lithium extraction adsorbent and the modified oxygen evolution catalyst are compounded to prepare the composite lithium extraction adsorbent, the composite lithium extraction adsorbent is electrified during the adsorption and lithium extraction process to ensure that OH- on the surface of the adsorbent is consumed, and also, the adverse effect of ClO- is eliminated, the alkalinity of the surface of the adsorbent is reduced, corrosion of the adsorbent is reduced, and the service life of the adsorbent is prolonged.

Description

A composite lithium extraction adsorbent and its preparation method and application Technical Field

[0001] The present invention belongs to the technical field of recycling and utilizing lithium precipitation mother liquor, and relates to a composite lithium extraction adsorbent, a preparation method thereof, and an application thereof. Background Art

[0002] With the rapid development of lithium-ion batteries, lithium resources have garnered widespread attention. my country boasts abundant salt lake lithium resources, with Qinghai Province alone possessing tens of thousands of tons of lithium chloride. Currently reported methods for extracting lithium from salt lakes include adsorption, precipitation, extraction, membrane separation, and calcination. Adsorption, however, has garnered significant attention in the field of lithium extraction from salt lake brines due to its suitability for salt lakes with high magnesium-to-lithium ratios, low production costs, simple process, and minimal energy consumption.

[0003] The adsorption method mainly uses an adsorbent to adsorb brine, remove magnesium, and concentrate to obtain a high-lithium and qualified liquid, and finally obtain a lithium carbonate product by washing with lithium precipitation. Since the solubility of lithium carbonate at the crystallization temperature of lithium precipitation is about 1g / 100g H2O, the concentration of lithium ions in the lithium precipitation mother liquor will be about 1-2g / L, which causes a huge waste of lithium ions. In addition, the lithium precipitation mother liquor also contains a large amount of sodium ions, carbonate ions, sulfate or chloride ions. If it is directly refluxed to the lithium extraction system, it will cause impurity ion negative electrode, and the discharge will cause a large amount of lithium ion waste. Moreover, the lithium precipitation mother liquor is highly alkaline, and there will be serious corrosion problems during the adsorption process, which seriously affects the recovery of lithium ions in the lithium precipitation mother liquor.

[0004] CN114853037A discloses a method for recovering lithium from lithium precipitation mother liquor. Before lithium precipitation, impurities such as boron, calcium and magnesium are removed from the concentrated brine after evaporation and concentration in the salt field. The method includes the following process steps and conditions: A. lithium precipitation: sodium phosphate is added to the lithium precipitation mother liquor, stirred and reacted to obtain lithium precipitation slurry, and the lithium precipitation slurry is subjected to conventional solid-liquid separation to obtain lithium phosphate and filtrate; B. transformation: lithium phosphate is slurried using boron-removed brine to transform into lithium chloride and slurry.

[0005] CN111533146A discloses a method for recovering lithium from a lithium carbonate precipitation mother liquor. The method comprises the following steps: 1. Adsorbing the lithium carbonate precipitation mother liquor using a titanium-based adsorbent for 0.5 to 12 hours; performing column adsorption or stirring adsorption to obtain an adsorbent A1 loaded with lithium ions and an adsorption mother liquor B1; 2. Adding an acid solution to the lithium ion-loaded adsorbent A1 obtained in step 1 and desorbing the lithium ions for 0.5 to 12 hours by column desorption or stirring desorption; obtaining an adsorbent A2 and a lithium-containing desorption liquid C1 after desorption of lithium ions; and recovering the lithium-containing desorption liquid C1 to obtain a lithium-containing compound.

[0006] The method for recovering lithium from lithium precipitation mother liquor described in the above scheme has a low lithium recovery rate, and the adsorbent is severely corroded during the recovery process, and it is impossible to achieve efficient lithium extraction in practical applications.

[0007] Summary of the Invention

[0008] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

[0009] The purpose of the present invention is to provide a composite lithium extraction adsorbent and its preparation method and application. The present invention prepares a composite lithium extraction adsorbent by combining a lithium extraction adsorbent and a modified oxygen evolution catalyst. When the composite lithium extraction adsorbent is electrified during the lithium extraction process, it can ensure that the OH on the surface of the adsorbent is consumed. - Eliminate ClO - It can reduce the adverse effects of adsorbents, reduce the alkalinity of the adsorbent surface, reduce the corrosion of the adsorbent, and increase the service life of the adsorbent.

[0010] To achieve this purpose, the present disclosure adopts the following technical solutions:

[0011] In a first aspect, the present disclosure provides a composite lithium extraction adsorbent, comprising a lithium extraction adsorbent and a modified oxygen evolution catalyst disposed on the surface of the lithium extraction adsorbent, wherein the modified oxygen evolution catalyst comprises a sulfur-containing NiFe-LDH oxygen evolution catalyst.

[0012] The present invention composites a modified oxygen evolution catalyst on the surface of a lithium extraction adsorbent. The modified oxygen evolution catalyst has a low overpotential. When the composite lithium extraction adsorbent is energized during lithium extraction, an electrolytic water-electrolysis oxygen evolution reaction occurs on the adsorbent surface. This ensures that the OH on the surface of the lithium extraction adsorbent is consumed. - Eliminate ClO - The adverse effects of the adsorbent can be reduced, thereby reducing the concentration of hydroxide on the surface of the composite adsorbent and reducing the corrosion problem of the adsorbent.

[0013] In one embodiment, the modified oxygen evolution catalyst is at 100 mA / cm 2 The overpotential is <300mV.

[0014] In one embodiment, the lithium-extracting adsorbent includes a manganese-based lithium ion-extracting adsorbent and / or a titanium-based lithium ion-extracting adsorbent eluted with acid.

[0015] In one embodiment, the molar concentration of the acid solution is 0.01 to 1 mol / L, for example, 0.01 mol / L, 0.05 mol / L, 0.1 mol / L, 0.5 mol / L or 1 mol / L.

[0016] In one embodiment, the acid solution includes any one of sulfuric acid, nitric acid, hydrochloric acid or oxalic acid, or a combination of at least two thereof.

[0017] In one embodiment, the manganese-based lithium ion screening lithium adsorbent comprises lithium manganate.

[0018] In one embodiment, the titanium-based lithium ion screening lithium adsorbent comprises lithium titanate.

[0019] In a second aspect, the present disclosure provides a method for preparing the composite lithium extraction adsorbent as described in the first aspect, the preparation method comprising the following steps:

[0020] (1) mixing a nickel source, an iron source, and urea with a solvent to obtain a mixed solution, and then adding a lithium extraction adsorbent to obtain a composite lithium extraction adsorbent precursor through a one-step reaction;

[0021] (2) Mixing the sulfur source solution with the lithium extraction adsorbent precursor to obtain the composite lithium extraction adsorbent through a two-step reaction.

[0022] The present invention discloses a composite lithium extraction adsorbent obtained by compounding a modified oxygen evolution catalyst with a lithium extraction adsorbent. The composite lithium extraction adsorbent can reduce the contact between the lithium extraction adsorbent and the strong alkaline lithium precipitation mother liquor. When power is applied during the lithium extraction adsorption process, the catalyst on the surface of the composite lithium extraction adsorbent can undergo an oxygen evolution reaction, consuming OH. - , reduce the alkalinity of the surface of the lithium extraction adsorbent, reduce the corrosion of the lithium extraction adsorbent, and increase the service life of the lithium extraction adsorbent.

[0023] In one embodiment, the nickel source in step (1) comprises nickel nitrate.

[0024] In one embodiment, the iron source comprises ferric nitrate.

[0025] In one embodiment, the molar ratio of the nickel source to the iron source is (1.8-2.2):1, for example: 1.8:1, 1.9:1, 2:1, 2.1:1 or 2.2:1.

[0026] In one embodiment, the molar concentration of the nickel source in the mixed solution is 0.02-0.03 mol / L, for example, 0.02 mol / L, 0.022 mol / L, 0.025 mol / L, 0.028 mol / L or 0.03 mol / L.

[0027] In one embodiment, the molar concentration of the iron source in the mixed solution is 0.01 to 0.015 mol / L, for example, 0.01 mol / L, 0.012 mol / L, 0.013 mol / L, 0.014 mol / L or 0.015 mol / L.

[0028] In one embodiment, the molar concentration of urea in the mixed solution is 0.1-0.2 mol / L, for example, 0.1 mol / L, 0.12 mol / L, 0.15 mol / L, 0.18 mol / L or 0.2 mol / L.

[0029] In one embodiment, the lithium extraction adsorbent in step (1) comprises lithium manganate and / or lithium titanate eluted with an acid solution.

[0030] In one embodiment, the temperature of the one-step reaction is 110-130°C, for example, 110°C, 115°C, 120°C, 125°C or 130°C.

[0031] In one embodiment, the one-step reaction time is 10 to 15 hours, for example, 10 hours, 11 hours, 12 hours, 13 hours or 15 hours.

[0032] In one embodiment, the one-step reaction is followed by washing and drying.

[0033] In one embodiment, the sulfur source solution in step (2) comprises a sodium sulfide solution.

[0034] In one embodiment, the molar concentration of the sulfur source solution is 0.01 to 0.02 mol / L, for example, 0.01 mol / L, 0.012 mol / L, 0.015 mol / L, 0.018 mol / L or 0.02 mol / L.

[0035] In one embodiment, the mass volume ratio of the lithium-extracting adsorbent precursor to the sulfur source solution is 80-120 g / L, for example, 80 g / L, 90 g / L, 100 g / L, 110 g / L or 120 g / L.

[0036] In one embodiment, the temperature of the second-step reaction in step (2) is 80-120°C, for example, 80°C, 90°C, 100°C, 110°C or 120°C.

[0037] In one embodiment, the two-step reaction time is 10 to 15 hours, for example, 10 hours, 11 hours, 12 hours, 13 hours or 15 hours.

[0038] In one embodiment, the two-step reaction is followed by washing and drying.

[0039] In a third aspect, the present disclosure provides a method for extracting lithium from a lithium precipitation mother liquor, wherein the method uses the composite lithium extraction adsorbent as described in the first aspect, and the method comprises the following steps:

[0040] (A) a composite lithium extraction adsorbent and a conductive agent are mixed and placed in an adsorption column, the adsorption column is placed in an adsorption tank provided with an anode electrode, the electrolyte is placed in an electrolyte tank provided with a cathode electrode, and a salt bridge is provided between the adsorption tank and the electrolyte tank;

[0041] (B) controlling the lithium precipitation mother liquor to flow through the adsorption tank while applying power to adsorb and extract lithium; after the adsorption is completed, rinsing and desorbing the composite lithium extraction adsorbent to obtain a lithium-rich solution.

[0042] In the lithium extraction method for lithium precipitation mother liquor disclosed in the present invention, lithium extraction by adsorption is only carried out on the surface of the lithium extraction adsorbent, and there is no need to add too much acid to adjust the overall pH value of the lithium extraction solution, which can reduce costs and environmental pressure, and the lithium extraction adsorbent can be repeatedly used in highly alkaline lithium precipitation mother liquor.

[0043] In one embodiment, the mass ratio of the composite lithium extraction adsorbent and the conductive agent in step (A) is (5-10):1, for example: 5:1, 6:1, 7:1, 8:1 or 10:1.

[0044] In one embodiment, the conductive agent includes any one of conductive carbon black, graphene, carbon nanotubes, or carbon fibers, or a combination of at least two thereof.

[0045] In one embodiment, the electrolyte comprises sodium sulfate solution and / or potassium sulfate solution.

[0046] In one embodiment, the molar concentration of the electrolyte is 0.1 to 1 mol / L, for example, 0.1 mol / L, 0.2 mol / L, 0.5 mol / L, 0.8 mol / L or 1 mol / L.

[0047] In one embodiment, the salt bridge comprises a potassium sulfate salt bridge and / or a sodium sulfate salt bridge.

[0048] In one embodiment, the molar concentration of the salt bridge is 3 to 5 mol / L, for example, 3 mol / L, 3.5 mol / L, 4 mol / L, 4.5 mol / L or 5 mol / L.

[0049] In one embodiment, the flow rate of the lithium precipitation mother liquor in step (B) is 2 to 10 n / h, for example, 2 n / h, 4 n / h, 6 n / h, 8 n / h or 10 n / h, etc., wherein n is the volume of the composite lithium extraction adsorbent.

[0050] In one embodiment, the voltage of the power supply is 1.3-1.55V, for example, 1.3V, 1.35V, 1.4V, 1.5V or 1.55V.

[0051] In one embodiment, the rinse detergent comprises deionized water.

[0052] In one embodiment, the desorption method includes acid washing.

[0053] As an optional solution of the present disclosure, the lithium extraction method includes the following steps:

[0054] (A) A composite lithium extraction adsorbent and a conductive agent are mixed in a mass ratio of (5-10):1 and placed in an adsorption column, the adsorption column is placed in an adsorption tank provided with an anode electrode, the electrolyte is placed in an electrolyte tank provided with a cathode electrode, and a salt bridge with a molar concentration of 3-5 mol / L is provided between the adsorption tank and the electrolyte tank;

[0055] (B) introducing a lithium precipitation mother liquor into the adsorption tank, wherein the volume of the composite lithium extraction adsorbent is n, controlling the flow rate of the lithium precipitation mother liquor to be 2 to 10 n / h, passing a voltage of 1.3 to 1.55 V to perform adsorption and lithium extraction, and after the adsorption is completed, rinsing and acid-washing the composite lithium extraction adsorbent to obtain a lithium-rich solution.

[0056] Compared with the prior art, the present disclosure has the following beneficial effects:

[0057] (1) The present invention composites a modified oxygen evolution catalyst on the surface of a lithium extraction adsorbent. The modified oxygen evolution catalyst has a low overpotential. When the composite lithium extraction adsorbent is energized during lithium extraction, an electrolytic water-electrolysis oxygen evolution reaction occurs on the adsorbent surface. This ensures that the OH on the surface of the lithium extraction adsorbent is consumed. - Eliminate ClO - The adverse effects of the adsorbent can be reduced, thereby reducing the concentration of hydroxide on the surface of the composite adsorbent and reducing the corrosion problem of the adsorbent.

[0058] (2) The composite lithium extraction adsorbent disclosed in the present invention adsorbs lithium in the lithium extraction mother solution under the condition of power supply, consuming OH - , reduce the alkalinity of the surface of the lithium extraction adsorbent, reduce the corrosion of the lithium extraction adsorbent, and increase the service life of the lithium extraction adsorbent.

[0059] (3) The composite lithium extraction adsorbent disclosed in the present invention is used in the process of lithium extraction from lithium precipitation mother liquor. The lithium adsorption capacity in the first cycle can reach more than 117.31 mg, and the lithium adsorption capacity after 100 cycles can still reach more than 116.46 mg. The average lithium recovery rate can reach more than 95.4%. The composite sulfur-modified Ni2Fe-LDH catalyst on the lithium extraction adsorbent can greatly improve the lithium extraction performance of the adsorbent under strong alkaline conditions.

[0060] Still other aspects will become apparent upon reading and understanding the accompanying drawings and detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0061] The accompanying drawings are used to provide a further understanding of the technical solution of this article and constitute a part of the specification. Together with the embodiments of this application, they are used to explain the technical solution of this article and do not constitute a limitation on the technical solution of this article.

[0062] Figure 1 is a schematic diagram of the device for the lithium extraction method described in Application Example 1 of the present disclosure, 1-anode electrode, 2-salt bridge, 3-cathode electrode, 4-adsorption column, 5-composite lithium extraction adsorbent, 6-conductive agent, 7-electrolyte. DETAILED DESCRIPTION

[0063] The technical solution of the present disclosure is further described below through specific implementation methods. It should be understood by those skilled in the art that the embodiments are only used to help understand the present disclosure and should not be regarded as specific limitations of the present disclosure.

[0064] Example 1

[0065] This embodiment provides a composite lithium extraction adsorbent, which is prepared by the following method:

[0066] (1) A mixed solution of nickel nitrate, 0.0125 mol / L ferric nitrate, and 0.15 mol / L urea was prepared, wherein the molar ratio of Ni:Fe in the mixed solution was 2:1, and the solution was stirred evenly at room temperature. An adsorbent (the adsorbent was lithium manganate that had been eluted with a 0.05 mol / L hydrochloric acid solution) was then added to the solution. After stirring evenly, the mixed suspension was transferred to a reactor and reacted at 120°C for 12 hours. After the reaction, the product was centrifuged and separated, washed twice with deionized water, and then vacuum dried at 60°C to obtain a composite adsorbent precursor.

[0067] (2) A 0.015 mol / L sodium sulfide solution was prepared, and the sodium sulfide solution and the composite adsorbent precursor were added to the reactor with a solid-liquid ratio of 100 g / L. The reaction was carried out at 100 °C for 12 h. After the reaction was completed, the product was centrifuged and separated, washed with deionized water three times, and then vacuum dried at 60 °C to obtain a composite adsorbent containing Ni2Fe-LDH / FeNi2S modified oxygen evolution catalyst.

[0068] Example 2

[0069] This embodiment provides a composite lithium extraction adsorbent, which is prepared by the following method:

[0070] (1) A mixed solution of nickel nitrate, 0.014 mol / L iron nitrate, and 0.17 mol / L urea with a Ni:Fe molar ratio of 2:1 was prepared and stirred at room temperature. An adsorbent (the adsorbent was lithium titanate eluted with a 0.05 mol / L hydrochloric acid solution) was then added to the solution. After stirring, the mixed suspension was transferred to a reactor and reacted at 100°C for 14 hours. After the reaction, the product was centrifuged and separated, washed twice with deionized water, and then dried in vacuum at 60°C to obtain a composite adsorbent precursor.

[0071] (2) A 0.018 mol / L sodium sulfide solution was prepared, and the sodium sulfide solution and the composite adsorbent precursor were added to a reactor with a solid-liquid ratio of 100 g / L. The reaction was carried out at 120°C for 8 h. After the reaction was completed, the product was centrifuged and separated, washed with deionized water three times, and then vacuum-dried at 60°C to obtain a composite adsorbent containing a Ni2Fe-LDH / FeNi2S modified oxygen evolution catalyst.

[0072] Example 3

[0073] This embodiment provides a composite lithium extraction adsorbent, which is prepared by the following method:

[0074] (1) A mixed solution of nickel nitrate, 0.015 mol / L ferric nitrate, and 0.2 mol / L urea was prepared, wherein the molar ratio of Ni:Fe in the mixed solution was 2:1, and the solution was stirred evenly at room temperature. An adsorbent (the adsorbent was lithium manganate that had been eluted with a 0.05 mol / L hydrochloric acid solution) was then added to the solution. After stirring evenly, the mixed suspension was transferred to a reactor and reacted at 110°C for 15 hours. After the reaction, the product was centrifuged and separated, washed twice with deionized water, and then vacuum dried at 60°C to obtain a composite adsorbent precursor.

[0075] (2) A 0.02 mol / L sodium sulfide solution was prepared, and the sodium sulfide solution and the composite adsorbent precursor were added to a reactor with a solid-liquid ratio of 120 g / L. The reaction was carried out at 120°C for 10 h. After the reaction was completed, the product was centrifuged and separated, washed with deionized water three times, and then vacuum-dried at 60°C to obtain a composite adsorbent containing a Ni2Fe-LDH / FeNi2S modified oxygen evolution catalyst.

[0076] Example 4

[0077] The only difference between this embodiment and embodiment 1 is that the molar concentration of the sodium sulfide solution is 0.005 mol / L, and the other conditions and parameters are exactly the same as those in embodiment 1.

[0078] Example 5

[0079] The only difference between this embodiment and embodiment 1 is that the molar concentration of the sodium sulfide solution is 0.03 mol / L, and the other conditions and parameters are exactly the same as those in embodiment 1.

[0080] Comparative Example 1

[0081] The only difference between this comparative example and Example 1 is that the adsorbent is not compounded, and the other conditions and parameters are exactly the same as those in Example 1.

[0082] Comparative Example 2

[0083] The only difference between this comparative example and Example 1 is that conventional unmodified Ni2Fe-LDH (100 mA / cm 2 The other conditions and parameters are exactly the same as those in Example 1.

[0084] Application Example 1

[0085] This application example provides a method for extracting lithium from a lithium precipitation mother liquor. A schematic diagram of the apparatus for the lithium extraction method is shown in FIG1 , wherein 1 is an anode electrode, 2 is a salt bridge, 3 is a cathode electrode, 4 is an adsorption column, 5 is a composite lithium extraction adsorbent, 6 is a conductive agent, and 7 is an electrolyte. The lithium extraction method comprises the following steps:

[0086] (1) The composite lithium extraction adsorbent prepared in Example 1 and conductive carbon black were mixed in a mass ratio of 5:1 and placed in an adsorption column. The adsorption column was placed in an adsorption tank (connected to the positive electrode), and a 0.5 mol / L sodium sulfate electrolyte was placed in an electrolyte tank (connected to the negative electrode). A salt bridge with a molar concentration of 4 mol / L was set between the adsorption tank and the electrolyte tank;

[0087] (2) The lithium precipitation mother liquor is introduced into the adsorption tank, the volume of the composite lithium extraction adsorbent is n, the flow rate of the lithium precipitation mother liquor is controlled to be 5n / h, and 1.5V is applied to adsorb and extract lithium. After the adsorption is completed, the composite lithium extraction adsorbent is rinsed and desorbed using 0.2mol / L sulfuric acid to obtain a lithium-rich solution.

[0088] Application Example 2

[0089] The only difference between this application example and application example 1 is that the composite lithium extraction adsorbent is prepared using Example 2, and the other conditions and parameters are exactly the same as those in application example 1.

[0090] Application Example 3

[0091] The only difference between this application example and application example 1 is that the composite lithium extraction adsorbent is prepared using Example 3, and the other conditions and parameters are exactly the same as those in application example 1.

[0092] Application Example 4

[0093] The only difference between this application example and application example 1 is that the composite lithium extraction adsorbent is prepared using Example 4, and the other conditions and parameters are exactly the same as those in application example 1.

[0094] Application Example 5

[0095] The only difference between this application example and application example 1 is that the composite lithium extraction adsorbent is prepared using Example 5, and the other conditions and parameters are exactly the same as those in application example 1.

[0096] Comparative Application Example 1

[0097] The only difference between this comparative application example and application example 1 is that the composite lithium extraction adsorbent is prepared using comparative example 1, and the other conditions and parameters are exactly the same as those in application example 1.

[0098] Comparative Application Example 2

[0099] The only difference between this comparative application example and application example 1 is that the composite lithium extraction adsorbent is prepared using comparative example 2, and the other conditions and parameters are exactly the same as those in application example 1.

[0100] Performance testing:

[0101] The adsorbed lithium amount and lithium recovery rate of the test application examples and comparative application examples were tested, where lithium recovery rate = (brine lithium concentration - adsorption tail liquid lithium concentration) / brine lithium concentration * 100%; adsorbed lithium amount = brine lithium concentration * adsorption brine volume * lithium recovery rate. The test results are shown in Table 1:

[0102] Table 1

[0103] As can be seen from Table 1, from Application Examples 1-3, the composite lithium extraction adsorbent disclosed in the present invention is used in the lithium extraction process of lithium precipitation mother liquor, and the lithium adsorption amount in the first cycle can reach more than 117.31 mg, and the lithium adsorption amount after 100 cycles can still reach more than 116.46 mg. The average lithium recovery rate can reach more than 95.4%. The composite sulfur-modified Ni2Fe-LDH catalyst on the lithium extraction adsorbent can greatly improve the lithium extraction performance of the adsorbent under strong alkaline conditions.

[0104] By comparing Example 1 with Examples 4-5, it can be seen that in the preparation process of the composite lithium extraction adsorbent described in the present disclosure, the concentration of the sulfur source solution used will affect its performance, and thus affect the lithium extraction effect. The molar concentration of the sulfur source solution is controlled at 0.01-0.02 mol / L, and the performance of the composite lithium extraction adsorbent obtained is better. If the molar concentration of the sulfur source solution is too low, the modification effect of sulfur ions on Ni2Fe-LDH is poor, and the improvement of the oxygen evolution electrocatalytic performance of Ni2Fe-LDH is not obvious. If the molar concentration of the sulfur source solution is too high, Ni2Fe-LDH is excessively converted into nickel-iron sulfide, which will also affect the oxygen evolution performance of the catalyst on the surface of the composite adsorbent.

[0105] From the comparison between Application Example 1 and Comparative Application Example 1, it can be seen that the present disclosure obtains the composite lithium extraction adsorbent by compounding the modified oxygen evolution catalyst with the lithium extraction adsorbent. The composite lithium extraction adsorbent can reduce the contact between the lithium extraction adsorbent and the strong alkaline lithium precipitation mother liquor. When power is applied during the lithium extraction adsorption process, the catalyst on the surface of the composite lithium extraction adsorbent can undergo oxygen evolution reaction, consuming OH - , reduce the alkalinity of the surface of the lithium extraction adsorbent, reduce the corrosion of the lithium extraction adsorbent, and increase the service life of the lithium extraction adsorbent.

[0106] From the comparison between Application Example 1 and Comparative Application Example 2, it can be seen that the modified oxygen evolution catalyst disclosed in the present invention has a lower overpotential than the conventional NiFe-LDH oxygen evolution catalyst, which can ensure that the oxygen evolution reaction occurs below the overpotential of chloride ion precipitation and reduce the hydroxide on the surface of the adsorbent. If a catalyst with an overpotential greater than 300 mV is used, the adverse effect of chloride ions on the adsorbent cannot be avoided well.

Claims

1. A composite lithium extraction adsorbent, comprising a lithium extraction adsorbent and a modified oxygen evolution catalyst disposed on the surface of the lithium extraction adsorbent, wherein the modified oxygen evolution catalyst comprises a sulfur-containing NiFe-LDH oxygen evolution catalyst.

2. The composite lithium extraction adsorbent according to claim 1, wherein: The modified oxygen evolution catalyst is 100 mA / cm 2 The overpotential is <300mV.

3. The composite lithium extraction adsorbent according to claim 1 or 2, wherein: The lithium-extracting adsorbent includes a manganese-based lithium-ion-extracting adsorbent and / or a titanium-based lithium-ion-extracting adsorbent eluted with an acid solution.

4. The composite lithium extraction adsorbent according to claim 3, wherein: The molar concentration of the acid solution is 0.01 to 1 mol / L; Optionally, the acid solution includes any one of sulfuric acid, nitric acid, hydrochloric acid or oxalic acid, or a combination of at least two of them.

5. The composite lithium extraction adsorbent according to claim 3 or 4, wherein: The manganese-based lithium ion screening lithium adsorbent includes lithium manganate; Optionally, the titanium-based lithium ion screening lithium adsorbent includes lithium titanate.

6. A method for preparing the composite lithium extraction adsorbent according to any one of claims 1 to 5, the preparation method comprising the following steps: (1) mixing a nickel source, an iron source and urea with a solvent to obtain a mixed solution, and then adding a lithium extraction adsorbent to obtain a composite lithium extraction adsorbent precursor through a one-step reaction; (2) Mixing the sulfur source solution with the lithium extraction adsorbent precursor to obtain the composite lithium extraction adsorbent through a two-step reaction.

7. The preparation method according to claim 6, wherein The nickel source in step (1) comprises nickel nitrate; Optionally, the iron source comprises ferric nitrate; Optionally, the molar ratio of the nickel source to the iron source is (1.8-2.2):1; Optionally, the molar concentration of the nickel source in the mixed solution is 0.02-0.03 mol / L; Optionally, the molar concentration of the iron source in the mixed solution is 0.01 to 0.015 mol / L; Optionally, the molar concentration of urea in the mixed solution is 0.1 to 0.2 mol / L; Optionally, the lithium extraction adsorbent includes lithium manganate and / or lithium titanate eluted with an acid solution.

8. The preparation method according to claim 6 or 7, wherein: The temperature of the one-step reaction is 110-130°C; Optionally, the one-step reaction time is 10 to 15 hours; Optionally, the one-step reaction is followed by washing and drying.

9. The preparation method according to any one of claims 6 to 8, wherein: The sulfur source solution in step (2) comprises a sodium sulfide solution; Optionally, the molar concentration of the sulfur source solution is 0.01 to 0.02 mol / L; Optionally, the mass volume ratio of the lithium extraction adsorbent precursor to the sulfur source solution is 80 to 120 g / L; Optionally, the temperature of the second step reaction is 80-120°C; Optionally, the two-step reaction time is 10 to 15 hours; Optionally, the two-step reaction is followed by washing and drying.

10. A method for extracting lithium from lithium precipitation mother liquor, the method using the composite lithium extraction adsorbent according to any one of claims 1 to 5, the method comprising the following steps: (A) mixing a composite lithium extraction adsorbent and a conductive agent and placing them in an adsorption column, wherein the adsorption column is placed in an adsorption tank provided with an anode electrode, and the electrolyte is placed in an electrolyte tank provided with a cathode electrode, and a salt bridge is provided between the adsorption tank and the electrolyte tank; (B) controlling the lithium precipitation mother liquor to flow through the adsorption tank, and simultaneously applying power to adsorb and extract lithium, and after the adsorption is completed, washing and desorbing the composite lithium extraction adsorbent to obtain a lithium-rich solution.

11. The lithium extraction method according to claim 10, wherein: The mass ratio of the composite lithium extraction adsorbent and the conductive agent in step (A) is (5-10):1; Optionally, the conductive agent includes any one or a combination of at least two of conductive carbon black, graphene, carbon nanotubes or carbon fibers; Optionally, the electrolyte includes sodium sulfate solution and / or potassium sulfate solution; Optionally, the molar concentration of the electrolyte is 0.1 to 1 mol / L; Optionally, the salt bridge comprises a potassium sulfate salt bridge and / or a sodium sulfate salt bridge; Optionally, the molar concentration of the salt bridge is 3 to 5 mol / L.

12. The lithium extraction method according to claim 10 or 11, wherein: The flow rate of the lithium precipitation mother solution in step (B) is 2 to 10 n / h, wherein n is the volume of the composite lithium extraction adsorbent; Optionally, the voltage of the power supply is 1.3 to 1.55V; Optionally, the rinsing detergent comprises deionized water; Optionally, the desorption method includes acid washing.

13. The lithium extraction method according to any one of claims 10 to 12, wherein: The lithium extraction method comprises the following steps: (A) a composite lithium extraction adsorbent and a conductive agent are mixed in a mass ratio of (5-10):1 and placed in an adsorption column, the adsorption column is placed in an adsorption tank provided with an anode electrode, the electrolyte is placed in an electrolyte tank provided with a cathode electrode, and a salt bridge with a molar concentration of 3-5 mol / L is set between the adsorption tank and the electrolyte tank; (B) A lithium precipitation mother liquor is introduced into the adsorption tank, the volume of the composite lithium extraction adsorbent is n, the flow rate of the lithium precipitation mother liquor is controlled to be 2-10n / h, 1.3-1.55V of electricity is passed to adsorb and extract lithium, and after the adsorption is completed, the composite lithium extraction adsorbent is rinsed and acid-washed for desorption to obtain a lithium-rich solution.

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