A composite lithium extraction adsorbent and its preparation method and application

Abstract

The present disclosure provides a composite lithium extraction adsorbent and a preparation method and application thereof, wherein the composite lithium extraction adsorbent comprises 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. The present disclosure prepares the composite lithium extraction adsorbent by combining the lithium extraction adsorbent and the modified oxygen evolution catalyst, and energizes the composite lithium extraction adsorbent during the lithium extraction adsorption process, so as to 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.

Description

Technical Field

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

[0002] With the rapid development of lithium-ion batteries, lithium resources have received extensive attention. my country has abundant salt lake lithium resources, with tens of thousands of tons of lithium chloride in Qinghai Province alone. The methods of extracting lithium from salt lakes that have been reported so far mainly include adsorption, precipitation, extraction, membrane separation, calcination, etc. Among them, the adsorption method has received extensive attention in the field of extracting lithium from salt lake brine because it is suitable for salt lakes with high magnesium-lithium ratios, and has low production costs, simple processes, and low energy consumption.

[0003] The adsorption method mainly uses an adsorbent to adsorb brine, remove magnesium, and concentrate to obtain high-lithium and qualified liquids, and finally obtain lithium carbonate products through lithium precipitation and washing. 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 great waste of lithium ions. In addition, the lithium precipitation mother liquor also contains a large amount of sodium ions, carbonate ions, sulfate ions 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 has a high alkalinity, 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, wherein impurities such as boron, calcium and magnesium in the concentrated brine after evaporation and concentration in the salt field are removed in advance before lithium precipitation, and the method comprises the following process steps and conditions: A. lithium precipitation: adding sodium phosphate to the lithium precipitation mother liquor, stirring and reacting to obtain lithium precipitation slurry, and subjecting the lithium precipitation slurry to conventional solid-liquid separation to obtain lithium phosphate and filtrate; B. transformation: using the boron-removing brine to slurry the lithium phosphate, and transforming to obtain lithium chloride and slurry.

[0005] CN111533146A discloses a method for recovering lithium from lithium carbonate mother liquor, comprising the following steps: step 1, using a titanium-based adsorbent to adsorb the lithium carbonate mother liquor for an adsorption time of 0.5 h to 12 h; the adsorption method is column adsorption or stirring adsorption to obtain an adsorbent A1 loaded with lithium ions and an adsorption mother liquor B1; step 2, adding an acid solution to the adsorbent A1 loaded with lithium ions obtained in step 1, and desorbing the adsorbent for 0.5 to 12 h, and the desorption method is column desorption or stirring desorption; obtaining an adsorbent A2 after desorption of lithium ions and a lithium-containing desorption liquid C1; 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 efficient lithium extraction cannot be achieved in practical applications. Summary of the invention

[0007] 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.

[0008] The purpose of the present invention is to provide a composite lithium extraction adsorbent and a preparation method and application thereof. The present invention prepares the composite lithium extraction adsorbent by combining the lithium extraction adsorbent and the modified oxygen evolution catalyst. During the lithium extraction adsorption process of the composite lithium extraction adsorbent, power is supplied to 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.

[0009] To achieve this purpose, the present invention adopts the following technical solutions:

[0010] 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.

[0011] 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. During the lithium extraction process of the composite lithium extraction adsorbent, electricity is applied to cause an electrolytic water-electrolysis oxygen evolution reaction to occur 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.

[0012] In one embodiment, the modified oxygen evolution catalyst is at 100 mA / cm 2 The overpotential is <300mV.

[0013] In one embodiment, the lithium-extracting adsorbent includes a manganese-based lithium-ion-extracting lithium adsorbent and / or a titanium-based lithium-ion-extracting lithium adsorbent eluted with an acid solution.

[0014] 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.

[0015] 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.

[0016] In one embodiment, the manganese-based lithium ion screening lithium adsorbent includes lithium manganate.

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

[0018] 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:

[0019] (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;

[0020] (2) Mixing the sulfur source solution with the lithium extraction adsorbent precursor to obtain the composite lithium extraction adsorbent through a two-step reaction.

[0021] The present invention 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 solution. 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.

[0022] In one embodiment, the nickel source in step (1) comprises nickel nitrate.

[0023] In one embodiment, the iron source comprises ferric nitrate.

[0024] 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, etc.

[0025] 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.

[0026] In one embodiment, the molar concentration of the iron source in the mixed solution is 0.01-0.015 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.

[0027] 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.

[0028] In one embodiment, the lithium extraction adsorbent in step (1) comprises lithium manganate and / or lithium titanate eluted with an acid solution.

[0029] 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.

[0030] 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.

[0031] In one embodiment, the one-step reaction is followed by washing and drying.

[0032] In one embodiment, the sulfur source solution in step (2) comprises a sodium sulfide solution.

[0033] In one embodiment, the molar concentration of the sulfur source solution is 0.01-0.02 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.

[0034] 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.

[0035] In one embodiment, the temperature of the two-step reaction in step (2) is 80-120°C, for example, 80°C, 90°C, 100°C, 110°C or 120°C.

[0036] 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.

[0037] In one embodiment, the two-step reaction is followed by washing and drying.

[0038] In a third aspect, the present disclosure provides a method for extracting lithium from a lithium precipitation mother liquor, wherein the lithium extraction method uses the composite lithium extraction adsorbent as described in the first aspect, and the lithium extraction method comprises the following steps:

[0039] (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;

[0040] (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.

[0041] In the lithium extraction method of the lithium precipitation mother liquor disclosed in the present invention, the adsorption and extraction of lithium 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 pressures, and the lithium extraction adsorbent can be repeatedly used in the highly alkaline lithium precipitation mother liquor.

[0042] 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, etc.

[0043] 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.

[0044] In one embodiment, the electrolyte includes sodium sulfate solution and / or potassium sulfate solution.

[0045] In one embodiment, the molar concentration of the electrolyte is 0.1-1 mol / L, for example, 0.1 mol / L, 0.2 mol / L, 0.5 mol / L, 0.8 mol / L or 1 mol / L.

[0046] In one embodiment, the salt bridge comprises a potassium sulfate salt bridge and / or a sodium sulfate salt bridge.

[0047] In one embodiment, the molar concentration of the salt bridge is 3-5 mol / L, for example, 3 mol / L, 3.5 mol / L, 4 mol / L, 4.5 mol / L or 5 mol / L.

[0048] 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.

[0049] In one embodiment, the powered voltage is 1.3-1.55V, for example, 1.3V, 1.35V, 1.4V, 1.5V or 1.55V.

[0050] In one embodiment, the rinse detergent comprises deionized water.

[0051] In one embodiment, the desorption method includes acid washing.

[0052] As an optional solution of the present disclosure, the lithium extraction method comprises the following steps:

[0053] (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;

[0054] (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.

[0055] Compared with the prior art, the present invention has the following beneficial effects:

[0056] (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. During the lithium extraction process of the composite lithium extraction adsorbent, electricity is applied to cause an electrolytic water-electrolysis oxygen evolution reaction to occur 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.

[0057] (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.

[0058] (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.

[0059] Other aspects will be apparent upon reading and understanding the drawings and detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] The accompanying drawings are used to provide further understanding of the technical solution of this article and constitute a part of the specification. Together with the embodiments of the present 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.

[0061] Figure 1 This 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

[0062] The technical solution of the present disclosure is further described below through specific implementation methods. Those skilled in the art should understand that the embodiments are only to help understand the present disclosure and should not be regarded as specific limitations of the present disclosure.

[0063] Example 1

[0064] This embodiment provides a composite lithium extraction adsorbent, which is prepared by the following method:

[0065] (1) preparing a mixed solution of 0.025 mol / L nickel nitrate, 0.0125 mol / L iron nitrate, and 0.15 mol / L urea, wherein the molar ratio of Ni:Fe in the mixed solution is 2:1, stirring the mixed solution uniformly at room temperature, then adding an adsorbent (the adsorbent is lithium manganate that has been eluted with a 0.05 mol / L hydrochloric acid solution) to the solution, stirring the mixed suspension uniformly, transferring the mixed suspension to a reactor and reacting it at 120°C for 12 hours, centrifuging and separating the product after the reaction, washing it twice with deionized water, and vacuum drying it at 60°C to obtain a composite adsorbent precursor;

[0066] (2) A 0.015 mol / L sodium sulfide solution was prepared, and the sodium sulfide solution and the composite adsorbent precursor were added into a reactor with a solid-liquid ratio of 100 g / L. The mixture was reacted at 100° C. for 12 h. After the reaction was completed, the product was separated by centrifugation, washed with deionized water for 3 times, and then vacuum dried at 60° C. to obtain a composite adsorbent containing a Ni2Fe-LDH / FeNi2S modified oxygen evolution catalyst.

[0067] Example 2

[0068] This embodiment provides a composite lithium extraction adsorbent, which is prepared by the following method:

[0069] (1) a mixed solution of 0.028 mol / L nickel nitrate, 0.014 mol / L iron nitrate and 0.17 mol / L urea, wherein the molar ratio of Ni:Fe in the mixed solution is 2:1, is stirred evenly at room temperature, and then an adsorbent (the adsorbent is lithium titanate that has been eluted with a 0.05 mol / L hydrochloric acid solution) is added to the solution, and after stirring evenly, the mixed suspension is transferred to a reactor and reacted at 100°C for 14 hours. After the reaction is completed, the product is separated by centrifugation, washed twice with deionized water and dried in vacuum at 60°C to obtain a composite adsorbent precursor;

[0070] (2) A 0.018 mol / L sodium sulfide solution was prepared, and the sodium sulfide solution and the composite adsorbent precursor were added into 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 separated by centrifugation, washed with deionized water for 3 times, and then vacuum dried at 60° C. to obtain a composite adsorbent containing a Ni2Fe-LDH / FeNi2S modified oxygen evolution catalyst.

[0071] Example 3

[0072] This embodiment provides a composite lithium extraction adsorbent, which is prepared by the following method:

[0073] (1) preparing a mixed solution of 0.03 mol / L nickel nitrate, 0.015 mol / L iron nitrate, and 0.2 mol / L urea, wherein the molar ratio of Ni:Fe in the mixed solution is 2:1, stirring the mixed solution uniformly at room temperature, then adding an adsorbent (the adsorbent is lithium manganate that has been eluted with a 0.05 mol / L hydrochloric acid solution) to the solution, stirring the mixed suspension uniformly, transferring the mixed suspension to a reactor and reacting it at 110°C for 15 hours, centrifuging the product after the reaction, washing it twice with deionized water, and vacuum drying it at 60°C to obtain a composite adsorbent precursor;

[0074] (2) A 0.02 mol / L sodium sulfide solution was prepared, and the sodium sulfide solution and the composite adsorbent precursor were added into 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 separated by centrifugation, washed with deionized water for 3 times, and then vacuum dried at 60° C. to obtain a composite adsorbent containing a Ni2Fe-LDH / FeNi2S modified oxygen evolution catalyst.

[0075] Example 4

[0076] 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.

[0077] Example 5

[0078] 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.

[0079] Comparative Example 1

[0080] 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.

[0081] Comparative Example 2

[0082] 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.

[0083] Application Example 1

[0084] This application example provides a method for extracting lithium from a lithium precipitation mother solution. The schematic diagram of the device for the lithium extraction method is as follows: Figure 1 As shown, 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 includes the following steps:

[0085] (1) The composite lithium extraction adsorbent prepared in Example 1 and the 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), a 0.5 mol / L sodium sulfate electrolyte was placed in an electrolyte tank (connected to the negative electrode), and a salt bridge with a molar concentration of 4 mol / L was set between the adsorption tank and the electrolyte tank;

[0086] (2) 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 5n / h, and 1.5V of electricity is passed to adsorb and extract lithium. After the adsorption is completed, the composite lithium extraction adsorbent is rinsed and desorbed using 0.2 mol / L sulfuric acid to obtain a lithium-rich solution.

[0087] Application Example 2

[0088] 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.

[0089] Application Example 3

[0090] 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.

[0091] Application Example 4

[0092] 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.

[0093] Application Example 5

[0094] 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.

[0095] Comparative application example 1

[0096] 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 of application example 1.

[0097] Comparative Application Example 2

[0098] 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 of application example 1.

[0099] Performance Test:

[0100] The adsorbed lithium amount and lithium recovery rate of the test application examples and comparative application examples, wherein lithium recovery rate = (lithium concentration of brine - lithium concentration of adsorbed tail liquid) / lithium concentration of brine * 100%; adsorbed lithium amount = lithium concentration of brine * volume of adsorbed brine * lithium recovery rate. The test results are shown in Table 1:

[0101] Table 1

[0102]

[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, 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 well 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 disclosed in the present invention, 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 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] By comparing Application Example 1 with 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, and the composite lithium extraction adsorbent can reduce the contact between the lithium extraction adsorbent and the strong alkaline lithium precipitation mother solution. 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 under the overpotential of chloride ion precipitation and reduce the hydroxide on the surface of the adsorbent. If a catalyst with an overpotential greater than 300mV 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; The lithium extraction adsorbent includes lithium manganate eluted with acid solution and / or lithium titanate eluted with acid solution.

2. The composite lithium extraction adsorbent according to claim 1, wherein: The modified oxygen evolution catalyst has a 2 The overpotential is <300mV.

3. The composite lithium extraction adsorbent according to claim 1, wherein: The molar concentration of the acid solution is 0.01-1 mol / L.

4. The composite lithium extraction adsorbent according to claim 1, wherein: 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. A method for preparing the composite lithium extraction adsorbent according to any one of claims 1 to 4, the preparation method comprising the following steps: (1) A nickel source, an iron source and urea are mixed with a solvent to obtain a mixed solution, and then a lithium extraction adsorbent is added to obtain a composite lithium extraction adsorbent precursor through a one-step reaction; The lithium extraction adsorbent includes lithium manganate eluted with acid solution and / or lithium titanate eluted with acid solution; (2) Mixing the sulfur source solution with the composite lithium extraction adsorbent precursor, and obtaining the composite lithium extraction adsorbent through a two-step reaction.

6. The preparation method according to claim 5, wherein The nickel source in step (1) includes nickel nitrate.

7. The preparation method according to claim 5, wherein The iron source includes ferric nitrate.

8. The preparation method according to claim 5, wherein The molar ratio of the nickel source to the iron source is (1.8-2.2):

1.

9. The preparation method according to claim 5, wherein: The molar concentration of the nickel source in the mixed solution is 0.02-0.03 mol / L.

10. The preparation method according to claim 5, wherein: The molar concentration of the iron source in the mixed solution is 0.01-0.015 mol / L.

11. The preparation method according to claim 5, wherein: The molar concentration of urea in the mixed solution is 0.1-0.2 mol / L.

12. The preparation method according to claim 5, wherein: The temperature of the one-step reaction is 110-130°C.

13. The preparation method according to claim 5, wherein: The one-step reaction time is 10 to 15 hours.

14. The preparation method according to claim 5, wherein: The one-step reaction is followed by washing and drying.

15. The preparation method according to claim 5, wherein: The sulfur source solution in step (2) includes a sodium sulfide solution.

16. The preparation method according to claim 5, wherein: The molar concentration of the sulfur source solution is 0.01-0.02 mol / L.

17. The preparation method according to claim 5, wherein: The mass volume ratio of the composite lithium extraction adsorbent precursor to the sulfur source solution is 80-120 g / L.

18. The preparation method according to claim 5, wherein: The temperature of the two-step reaction is 80-120°C.

19. The preparation method according to claim 5, wherein: The time of the two-step reaction is 10 to 15 hours.

20. The preparation method according to claim 5, wherein: The two-step reaction is followed by washing and drying.

21. 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 4, the method comprising the following steps: (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, an 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, while 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.

22. The lithium extraction method according to claim 21, wherein: The mass ratio of the composite lithium extraction adsorbent and the conductive agent in step (A) is (5-10):

1.

23. The lithium extraction method according to claim 21, wherein: The conductive agent includes any one of conductive carbon black, graphene, carbon nanotubes or carbon fibers, or a combination of at least two of them.

24. The lithium extraction method according to claim 21, wherein: The electrolyte includes sodium sulfate solution and / or potassium sulfate solution.

25. The lithium extraction method according to claim 21, wherein: The molar concentration of the electrolyte is 0.1-1 mol / L.

26. The lithium extraction method according to claim 21, wherein: The salt bridge comprises a potassium sulfate salt bridge and / or a sodium sulfate salt bridge.

27. The lithium extraction method according to claim 21, wherein: The molar concentration of the salt bridge is 3-5 mol / L.

28. The method for extracting lithium according to claim 21, wherein: In step (B), the flow rate of the lithium precipitation mother liquor is 2-10 n / h, wherein n is the volume of the composite lithium extraction adsorbent.

29. The lithium extraction method according to claim 21, wherein: The voltage of the power supply is 1.3~1.55V.

30. The lithium extraction method according to claim 21, wherein: The rinse detergent includes deionized water.

31. The lithium extraction method according to claim 21, wherein: The desorption method includes pickling.

32. The lithium extraction method according to claim 21, 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, and 1.3~1.55V of electricity is passed to adsorb and extract lithium. 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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