Lithium adsorbent, and preparation method and application thereof

Abstract

The present application relates to a kind of lithium adsorbent and its preparation method and application, the method includes the following steps: providing first mixture, the first mixture includes water-soluble lithium salt, water-soluble aluminum salt and silane amino acid;The first mixture is coprecipitation with alkaline solution, and second mixture is obtained;And the second mixture is aged;Wherein, by water-soluble amino acid and isocyanate silane are prepared the silane amino acid;The water-soluble amino acid includes aspartic acid, glutamic acid, histidine, lysine, arginine, serine, threonine, cysteine, asparagine, glutamine one or more thereof.The preparation method of an embodiment of the present application is prepared lithium adsorbent, with high cyclic adsorption capacity, stable performance, long service life characteristics.

Description

Technical Field

[0001] This invention relates to the separation of lithium, and more particularly to an adsorbent capable of efficiently extracting lithium. Background Technology

[0002] Lithium, as the lightest metallic element in nature with the lowest standard electrode potential and the smallest electrochemical equivalent, has wide applications in 3C digital products, electric vehicles, and energy storage. Lithium resource supply is divided into three major systems: lithium ore, lepidolite, and brine from salt lakes, with brine resources accounting for approximately 70% of the global lithium resource total. Furthermore, the lower cost and faster technological upgrades of lithium extraction from salt lakes suggest that they are poised to become a major source of lithium supply in the future.

[0003] The technological routes for lithium extraction from salt lakes exhibit a "one lake, one policy" characteristic, varying according to the vast differences in brine resource endowment. The main developments include precipitation, extraction, membrane separation, and diversified technological paths such as electrodialysis, electrochemical deintercalation, and adsorption. Among these, the core of the adsorption method lies in developing lithium adsorbents with large adsorption capacity, high selectivity, and long lifespan. Lithium adsorbents mainly include aluminum-based lithium adsorbents, manganese-based lithium ion sieves, and titanium-based lithium ion sieve adsorbents, among which aluminum-based adsorbents are currently the most mature and the only industrialized lithium adsorbent.

[0004] The structure of aluminum-based lithium adsorbent powder is generally represented as LiCl·2Al(OH)3·nH2O or similar compounds. For existing aluminum-based lithium adsorbents, during actual operation of the granulated and packed adsorption tower, to maintain the layered structure of the top adsorbent from collapse and damage, after water washing to remove lithium, the lithium removal rate of the upper section of the adsorbent in the adsorption tower remains at around 60%, while the lithium removal rate in the middle and lower sections is only 10%-20%. During the lithium adsorbent elution process, Li... + Incomplete elution leads to a significant reduction in the number of effective vacancies released, resulting in a large discrepancy between the adsorption capacity during recycling and the theoretical adsorption capacity, thus reducing production efficiency. When the production process is adjusted, such as increasing the elution volume or raising the elution water temperature, excessive lithium intercalation / deintercalation may occur in the adsorbent, causing all Cl₂ in the interlayer to be lost. - Once all the lithium has been removed from the adsorbent, the layered structure will collapse, and the lithium adsorbent will no longer have the ability to adsorb lithium. Summary of the Invention

[0005] To overcome at least one of the defects of the prior art, in a first aspect, one embodiment of the present invention provides a method for preparing a lithium adsorbent, comprising the following steps:

[0006] A first mixture is provided, the first mixture comprising a water-soluble lithium salt, a water-soluble aluminum salt, and a silane amino acid;

[0007] The first mixture was subjected to a co-precipitation reaction with an alkaline solution to obtain a second mixture; and

[0008] The second mixture is then aged.

[0009] The silane amino acid is prepared by reacting water-soluble amino acids with isocyanate silanes. The water-soluble amino acids include one or more of aspartic acid, glutamic acid, histidine, lysine, arginine, serine, threonine, cysteine, asparagine, and glutamine.

[0010] Secondly, one embodiment of the present invention provides a lithium adsorbent, which is prepared by the above-described preparation method.

[0011] Thirdly, one embodiment of the present invention provides the application of the lithium adsorbent prepared by the above-described preparation method in lithium extraction from salt lakes.

[0012] The lithium adsorbent prepared by the preparation method of one embodiment of the present invention has the characteristics of high cyclic adsorption capacity, stable performance and long service life. Attached Figure Description

[0013] The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of the invention. Wherein:

[0014] Figure 1 The image shows the XRD pattern of the lithium adsorbent prepared in Example 1 of this invention.

[0015] Figure 2 The image shows the XRD pattern of the lithium adsorbent prepared in Comparative Example 1 of this invention. Detailed Implementation

[0016] Typical embodiments embodying the features and advantages of the present invention will be described in detail in the following description. It should be understood that the present invention can have various variations in different embodiments without departing from the scope of the present invention, and the description herein is for illustrative purposes only and not intended to limit the present invention.

[0017] One embodiment of the present invention provides a method for preparing a lithium adsorbent, comprising the following steps:

[0018] A first mixture is provided, comprising a water-soluble lithium salt, a water-soluble aluminum salt, and a silane amino acid;

[0019] The first mixture was subjected to a co-precipitation reaction with an alkaline solution to form a nascent lithium aluminum bis hydroxide precipitate, yielding a second mixture; and

[0020] The second mixture is then aged.

[0021] The method involves preparing silane amino acids by an addition reaction of water-soluble amino acids with isocyanate silanes; the water-soluble amino acids include one or more of aspartic acid, glutamic acid, histidine, lysine, arginine, serine, threonine, cysteine, asparagine, and glutamine; preferably, the water-soluble amino acids are selected from one or more of aspartic acid, glutamic acid, histidine, lysine, and arginine; more preferably, the water-soluble amino acids are selected from one or two of aspartic acid and glutamic acid.

[0022] In one embodiment, the method for preparing the lithium adsorbent includes:

[0023] Silane amino acids are prepared by adding water-soluble amino acids to isocyanate silanes.

[0024] A first mixture is obtained by mixing a water-soluble lithium salt, a water-soluble aluminum salt, a silane amino acid, and a solvent (e.g., water).

[0025] The first mixture was added dropwise to an alkaline solution to carry out a co-precipitation reaction, yielding a second mixture;

[0026] The second mixture was aged to obtain the third mixture.

[0027] In one embodiment, water-soluble lithium salt refers to a lithium salt that can dissolve in water, such as one or more of lithium chloride, lithium bromide, and lithium nitrate.

[0028] In one embodiment, water-soluble aluminum salts refer to aluminum salts that are soluble in water, such as one or more of aluminum chloride, aluminum bromide, and aluminum nitrate.

[0029] In one embodiment, water-soluble amino acids refer to amino acids that can dissolve in water.

[0030] In one embodiment, the isocyanate silane includes one or more of α-isocyanate-methyltrimethoxysilane, α-isocyanate-methyltriethoxysilane, γ-isocyanate-propyltrimethoxysilane, and γ-isocyanate-propyltriethoxysilane.

[0031] In one embodiment, the reaction temperature between the water-soluble amino acid and the isocyanate silane can be 10–35°C, for example 15°C, 20°C, 25°C, or 30°C; and the time can be 10–20 h, for example 12 h, 15 h, 17 h, or 19 h.

[0032] In one embodiment, the molar ratio of water-soluble amino acid to isocyanate silane is 1:(1 to 1.2), for example 1:1, 1:1.05, 1:1.1, preferably 1:1.

[0033] In one embodiment, the molar concentration of the alkaline solution is 4.5 to 5.8 mol / L, for example, 4.8 mol / L, 5.0 mol / L, 5.2 mol / L, or 5.4 mol / L; further, the alkaline solution may include one or more of sodium hydroxide, potassium hydroxide, and ammonia water.

[0034] In one embodiment, the molar ratio of aluminum salt to silane amino acid is 2:(0.04-0.15), for example 2:0.05, 2:0.06, 2:0.08, 2:0.1, 2:0.12, 2:0.14; preferably, the molar ratio of aluminum salt to silane amino acid is 2:(0.08-0.12).

[0035] In one embodiment, the molar ratio of lithium salt to aluminum salt is (0.9–2):2, for example, 1:2, 1.2:2, 1.5:2, 1.6:2, or 1.8:2; preferably, the molar ratio of lithium salt to aluminum salt is (1.2–1.5):2.

[0036] In one embodiment, the molar ratio of lithium salt, aluminum salt, and silane amino acid is (0.9-2):2:(0.04-0.15).

[0037] In one embodiment, the temperature of the coprecipitation reaction can be 60–90°C, for example 65°C, 70°C, 75°C, 80°C, or 85°C; the endpoint pH of the coprecipitation reaction is 4.5–5.5, for example 4.8 or 5.0.

[0038] In one embodiment, the aging process is continued at the above-mentioned reaction temperature under the action of stirring; the aging time can be 0.5 to 3 hours, for example 1 hour, 1.5 hours, 2 hours, or 2.5 hours.

[0039] In one embodiment, the third mixture is filtered, washed with water, and dried to obtain a lithium adsorbent. Further, the dried material can be crushed to obtain a powdered lithium adsorbent.

[0040] One embodiment of the present invention provides a lithium adsorbent, which is prepared by the above-described preparation method.

[0041] In one embodiment, the lithium adsorbent has a silane amino acid-pillared lithium aluminum double hydroxide layered structure.

[0042] One embodiment of the present invention provides the application of the above-mentioned lithium adsorbent in lithium extraction from salt lakes.

[0043] This invention discloses a method for preparing a lithium adsorbent by introducing silane-modified amino acids as pillar structures into a layered structure. This results in a lithium adsorbent with high cyclic adsorption capacity, stable performance, and long service life. Specifically, modifying the amino acids with silane before introducing them into the layered structure allows the amino acids to be fixed between the layers through covalent bonds and other interactions, improving the stability of the pillar structure and thus enhancing the adsorbent's adsorption capacity and long-term cyclic adsorption performance.

[0044] The lithium adsorbent of one embodiment of the present invention can be used for long-term recycling at a high elution rate of 85-100%, which greatly improves the production efficiency and solves the problem of low production efficiency of existing aluminum-based lithium adsorbents; at the same time, it can reduce the amount of adsorbent used in a 10,000-ton lithium carbonate plant.

[0045] The preparation method of lithium adsorbent according to one embodiment of the present invention is simple and can greatly improve the cyclic adsorption capacity of the adsorbent by using a small amount of amino acids.

[0046] The preparation method of the lithium adsorbent according to one embodiment of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. The main raw materials used are shown in the table below; other raw materials are common commercially available products and can be purchased from reagent suppliers such as Inokai and Aladdin.

[0047]

[0048] Example 1

[0049] (1) 13.31 g (0.1 mol) of L-aspartic acid was placed in 150 mL of dehydrated tetrahydrofuran, and 20.53 g (0.1 mol) of γ-isocyanate-propyltrimethoxysilane was added dropwise under magnetic stirring in a water bath at 25 °C. The reaction was continued for 15 h, and the solvent was evaporated to obtain trimethoxysilane-propylurea-aspartic acid.

[0050] (2) Weigh 241.43g AlCl3·6H2O (1mol), 25.43g LiCl (0.6mol) and 16.92g trimethoxysilanepropylurea-aspartic acid (0.05mol) respectively, add them to 300mL of deionized water, stir and mix evenly to obtain the first mixture.

[0051] (3) The first mixture was added to 500 mL of NaOH solution (5.4 mol / L) at a dropping rate of 10 mL / min. The water bath temperature used to heat the reaction system was 80 °C, the stirring speed of the reaction system was 250 r / min, the pH of the dropping endpoint was 5.0, and the second mixture was obtained after the dropping was completed.

[0052] (4) Continue stirring and aging the second mixture system obtained in step (3) at 80°C for 2 hours to obtain the third mixture.

[0053] (5) The third mixture is filtered, washed, dried and crushed to obtain urea-aspartic acid intercalated powdered lithium adsorbent.

[0054] Example 2

[0055] (1) 14.71 g (0.1 mol) of L-glutamic acid was placed in 150 mL of dehydrated tetrahydrofuran, and 24.73 g (0.1 mol) of γ-isocyanate-propyltriethoxysilane was added dropwise under magnetic stirring in a water bath at 20 °C. The reaction was continued for 17 h, and the solvent was evaporated to obtain triethoxysilane-propylurea-glutamic acid.

[0056] (2) Weigh 375.13g Al(NO3)3·9H2O (1mol), 51.72g LiNO3 (0.75mol) and 7.89g triethoxysilanepropylurea glutamic acid (0.02mol) respectively, add them to 300mL of deionized water, stir and mix evenly to obtain the first mixture.

[0057] (3) The first mixture was added to 500 mL of NaOH solution (4.5 mol / L) at a dropping rate of 10 mL / min. The water bath temperature used to heat the reaction system was 90 °C, the stirring speed of the reaction system was 250 r / min, the pH at the drop end was 4.8, and the second mixture was obtained after the drop was completed.

[0058] (4) The second mixture system obtained in step (3) is stirred and aged at 90°C for 0.5 h to obtain the third mixture.

[0059] (5) The third mixture is filtered, washed, dried and crushed to obtain urea-glutamic acid intercalated powdered lithium adsorbent.

[0060] Example 3

[0061] (1) 14.62 g (0.1 mol) of L-lysine was placed in 150 mL of dehydrated tetrahydrofuran, and 17.72 g (0.1 mol) of α-isocyanate-methyltrimethoxysilane was added dropwise under magnetic stirring in a water bath at 10 °C. The reaction was continued for 20 h, and the solvent was evaporated to obtain trimethoxysilane-methylurea-lysine.

[0062] (2) Weigh 266.69g AlBr3 (1mol), 39.08g LiBr (0.45mol) and 24.26g trimethoxysilane methylurea lysine (0.075mol) respectively, add them to 300mL of deionized water, stir and mix evenly to obtain the first mixture.

[0063] (3) The first mixture was added to 500 mL of ammonia solution (5.0 mol / L) at a dropping rate of 10 mL / min. The water bath temperature used to heat the reaction system was 65 °C, the stirring speed of the reaction system was 250 r / min, the pH at the droplet endpoint was 4.5, and the second mixture was obtained after the droplet addition was completed.

[0064] (4) Continue stirring and aging the second mixture system obtained in step (3) at 65°C for 3 hours to obtain the third mixture.

[0065] (5) The third mixture is filtered, washed, dried and crushed to obtain urea-lysine-intercalated lithium adsorbent powder.

[0066] Example 4

[0067] (1) 11.91 g (0.1 mol) L-threonine was placed in 150 mL of dehydrated tetrahydrofuran, and 21.93 g (0.1 mol) α-isocyanate-methyltriethoxysilane was added dropwise under magnetic stirring in a water bath at 30 °C. The reaction was continued for 12 h, and the solvent was evaporated to obtain triethoxysilane-methylurea-threonine.

[0068] (2) Weigh 241.43g AlCl3·6H2O (1mol), 86.85g LiBr (1mol) and 13.54g triethoxysilanemethylureathreonine (0.04mol) respectively, add them to 300mL of deionized water, stir and mix evenly to obtain the first mixture.

[0069] (3) The first mixture was added to 500 mL of NaOH solution (5.8 mol / L) at a rate of 10 mL / min to carry out the reaction. The water bath temperature used to heat the reaction system was 70 °C, the stirring speed of the reaction system was 250 r / min, the pH of the droplet addition endpoint was 5.5, and the second mixture was obtained after the droplet addition was completed.

[0070] (4) The second mixture system obtained in step (3) is further stirred and aged at 70°C for 2.5 h to obtain the third mixture.

[0071] (5) The third mixture is filtered, washed, dried and crushed to obtain ureothreonine-intercalated lithium adsorbent powder.

[0072] Example 5

[0073] (1) 15.62 g (0.1 mol) of L-arginine was placed in 150 mL of dehydrated tetrahydrofuran. 17.72 g (0.1 mol) of α-isocyanate-methyltrimethoxysilane was added dropwise under magnetic stirring in a water bath at 35 °C. The reaction was continued for 10 h. After evaporating the solvent, trimethoxysilane-methylurea-arginine was obtained.

[0074] (2) Weigh 375.13g Al(NO3)3·9H2O (1mol), 33.91g LiCl (0.8mol) and 23.34g trimethoxysilanemethylureaarginine (0.07mol) respectively, add them to 300mL of deionized water, stir and mix evenly to obtain the first mixture.

[0075] (3) The first mixture was added to 500 mL of KOH solution (4.8 mol / L) at a dropping rate of 10 mL / min. The water bath temperature used to heat the reaction system was 60 °C, the stirring speed of the reaction system was 250 r / min, the pH at the drop end was 5.2, and the second mixture was obtained after the drop was completed.

[0076] (4) Continue stirring and aging the second mixture system obtained in step (3) at 60°C for 3 hours to obtain the third mixture.

[0077] (5) The third mixture is filtered, washed, dried and crushed to obtain urea-arginine intercalated powdered lithium adsorbent.

[0078] Example 6

[0079] (1) 12.81 g (0.1 mol) L-glutamine was placed in 150 mL of dehydrated tetrahydrofuran, and 20.53 g (0.1 mol) γ-isocyanate-propyltrimethoxysilane was added dropwise under magnetic stirring in a water bath at 15 °C. The reaction was continued for 19 h, and the solvent was evaporated to obtain trimethoxysilane-propylurea-glutamine.

[0080] (2) Weigh 266.69g AlBr3 (1mol), 34.48g LiNO3 (0.5mol) and 20.00g trimethoxysilanepropylurea glutamine (0.06mol) respectively, add them to 300mL of deionized water, stir and mix evenly to obtain the first mixture.

[0081] (3) The first mixture was added to 500 mL of KOH solution (5.2 mol / L) at a dropping rate of 10 mL / min. The water bath temperature used to heat the reaction system was 75 °C, the stirring speed of the reaction system was 250 r / min, the pH of the dropping endpoint was 5.0, and the second mixture was obtained after the dropping was completed.

[0082] (4) The second mixture system obtained in step (3) is stirred and aged at 75°C for 1.5 h to obtain the third mixture.

[0083] (5) The third mixture is filtered, washed, dried and crushed to obtain urea-glutamine intercalated powdered lithium adsorbent.

[0084] Comparative Example 1

[0085] (1) Weigh 241.43g AlCl3·6H2O (1mol) and 25.43g LiCl (0.6mol) respectively, add them to 300mL of deionized water, and stir to mix evenly.

[0086] (2) The mixture obtained in step (1) was added to 500 mL of ammonia solution (5.4 mol / L) at a dropping rate of 10 mL / min for reaction. The water bath temperature used to heat the reaction system was 80 °C, the stirring speed was 250 r / min, and the pH at the drop end was 5.0.

[0087] (3) Continue stirring and aging the system from step (2) at 80°C for 2 hours.

[0088] (4) The system of step (3) is filtered, washed, dried and crushed to obtain powdered lithium adsorbent.

[0089] Comparative Example 2

[0090] (1) Weigh out 241.43g AlCl3·6H2O (1mol), 25.43g LiCl (0.6mol), and 6.66g L-aspartic acid (0.05mol), respectively, and add them to 300mL of deionized water. Stir and mix evenly.

[0091] (2) The mixture obtained in step (1) was added to 500 mL of ammonia solution (5.4 mol / L) at a dropping rate of 10 mL / min for reaction. The water bath temperature used to heat the reaction system was 80 °C, the stirring speed was 250 r / min, and the pH at the drop end was 5.0.

[0092] (3) Continue stirring and aging the system from step (2) at 80°C for 2 hours.

[0093] (4) The system of step (3) is filtered, washed, dried and crushed to obtain aspartic acid intercalated powdered lithium adsorbent.

[0094] XRD test

[0095] The lithium adsorbents prepared in each embodiment and comparative example were tested using X-ray powder polycrystalline diffraction (XRD). The operating parameters were: Cu-Kα target, scanning voltage / current of 45 kV / 40 mA, scanning range of 5-80°, and scanning step size of 0.02°. For detailed results, please refer to [link to specific results]. Figure 1 , 2 See Table 1.

[0096] Table 1. XRD interlayer spacing results of lithium adsorbents in Examples 1-6 and Comparative Examples 1-2

[0097]

[0098] As can be seen from the descriptions of the various embodiments and comparative examples, silane amino acids were used in the preparation of the lithium adsorbents in Examples 1-6, while silane amino acids were not used in Comparative Example 1, and aspartic acid was used instead of silane amino acids in Comparative Example 2. Figure 1 , 2 The results show that the use of silane amino acids did not change the overall structure of the adsorbent prepared in Example 1. The structure of the prepared adsorbent is roughly the same as that of the adsorbent in Comparative Example 1, and it still maintains a layered structure.

[0099] Furthermore, according to the results in Table 1, the interlayer spacing of the lithium adsorbents in Examples 1-6 is significantly larger than that in Comparative Example 1, indicating that the silane amino acids introduced into the interlayer structure can act as pillar structures, increasing the interlayer distance. Although the interlayer spacing of Comparative Example 2 is slightly increased compared to Comparative Example 1, it is still significantly smaller than that of Examples 1-6, indicating that modifying the amino acids with silane before introducing them into the layered structure of the adsorbent can enhance their role as pillar structures.

[0100] Adsorption performance test

[0101] The lithium adsorbents prepared in each embodiment and comparative example were subjected to adsorption performance tests. The pretreatment method of the adsorbent is as follows: the adsorbent was stirred and eluted in hot water at 50℃ (safe deintercalation) and hot water at 80℃ (excessive deintercalation) at a ratio of 1g adsorbent / 80mL water for 2h to form lithium ion vacancies, and then filtered and dried to obtain the effective adsorbent.

[0102] The test method for the lithium-aluminum composition of the adsorbent is as follows: Take 0.1g of lithium adsorbent, dissolve it in 2ml of concentrated nitric acid, and then dilute it with ultrapure water to the test range of the inductively coupled plasma optical emission spectrometer (ICP-OES). Calculate the molar ratio of lithium to aluminum using the test data of lithium and aluminum elements.

[0103] The test method for the saturated adsorption capacity of the adsorbent is as follows: Weigh 0.5g of pretreated lithium adsorbent, add 50g of old brine from Chaka Salt Lake, and place it in a constant temperature shaker at 25℃. Set the shaker speed to 150rpm. After adsorption for 15h, test the lithium content in the brine before and after adsorption, and calculate the saturated adsorption capacity. The results are shown in Table 3.

[0104] The formula for calculating the adsorption capacity is: Saturated adsorption capacity = (Lithium content in the brine before adsorption - Lithium content in the brine after adsorption) * Mass of salt lake brine / Mass of adsorbent.

[0105] Table 2 Chemical composition of Chaka Salt Lake Brine

[0106] element Li Na K Mg B mg / kg 296 1650 850 87869 257

[0107] Table 3. Molar ratio of lithium to aluminum and saturated adsorption capacity after elution with lithium adsorbent.

[0108]

[0109] As shown in Table 3, after elution in hot water at 50°C, 25-60% of lithium ions remained in the structure of the lithium adsorbents in each example and comparative example, with a measured saturated adsorption capacity of approximately 15-17 mg / g. However, after elution in hot water at 80°C, approximately 90% of the lithium ions in the lithium adsorbents of each example and comparative example were removed. The lithium adsorbents in Examples 1-6 maintained their original layered structure due to the pillaring effect of silane amino acids, and their saturated adsorption capacity increased to over 30 mg / g. In contrast, the lithium adsorbent in Comparative Example 1 collapsed due to the removal of the vast majority of lithium ions and interlayer chloride ions, resulting in almost no adsorption capacity. In Comparative Example 2, due to the lack of covalent fixation of interlayer amino acids, some were eluted, failing to fully exert the pillaring effect and retaining only the original adsorption capacity.

[0110] Long-term cyclic adsorption performance test

[0111] The lithium adsorbents prepared in each embodiment and comparative example were subjected to long-term cyclic adsorption performance tests, as follows:

[0112] (1) Adsorption process: Weigh 5g of lithium adsorbent that has been pretreated with hot water at 50℃, add 200g of old brine from Chahar, and adsorb for 4h at 150rpm in a constant temperature shaker at 25℃. Separate the adsorption tail liquid from the adsorbent by centrifugation and determine the lithium content in the adsorption tail liquid.

[0113] (2) Washing process: Add 50g of pure water to the above-mentioned saturated lithium adsorbent, mix quickly for 5min, and centrifuge to separate the washing solution from the adsorbent.

[0114] (3) Desorption process: Add 100g of pure water to the lithium adsorbent after washing with water, and wash for 2 hours at 150rpm in a constant temperature shaker at 60℃. Separate the desorbed liquid from the adsorbent by centrifugation and determine the lithium content in the desorbed liquid.

[0115] The processes (1), (2), and (3) above represent a complete adsorption cycle. This cycle is repeated to test the long-term cyclic adsorption performance of the lithium adsorbent.

[0116] The formula for calculating the working desorption capacity is: Desorption capacity = Lithium content in the desorption solution * Mass of the desorption solution / Mass of the adsorbent; The formula for calculating the working adsorption capacity is the same as the formula for calculating the saturated adsorption capacity mentioned above.

[0117] Table 4 Initial adsorption and desorption capacities of lithium adsorbent and adsorption and desorption capacities at the 50th cycle.

[0118]

[0119] As shown in Table 4, after 50 cycles of adsorption-desorption cycling experiments, the lithium adsorbents prepared in Examples 1-6 still maintained high adsorption and desorption capacities, exhibiting characteristics of high cyclic adsorption-desorption capacity, stable performance, and long service life. In contrast, the lithium adsorbent prepared in Comparative Example 1 showed a sharp decline in adsorption and desorption capacity due to long-term heating and desorption. The amino acid physically intercalated lithium adsorbent prepared in Comparative Example 2 also exhibited adsorption and desorption capacity degradation.

[0120] Unless otherwise specified, the terms used in this invention have the meanings commonly understood by those skilled in the art.

[0121] The embodiments described in this invention are for illustrative purposes only and are not intended to limit the scope of protection of this invention. Those skilled in the art can make various other substitutions, changes and improvements within the scope of this invention. Therefore, this invention is not limited to the above embodiments, but is only defined by the claims.

Claims

1. A method for preparing a lithium adsorbent, comprising the following steps: providing a first mixture, wherein the first mixture comprises a water-soluble lithium salt, a water-soluble aluminum salt and a silane amino acid; co-precipitating the first mixture with an alkaline solution to obtain a second mixture; and aging the second mixture; wherein the silane amino acid is prepared by reacting a water-soluble amino acid with an isocyanate silane, wherein the water-soluble amino acid comprises one or more of aspartic acid, glutamic acid, histidine, lysine, arginine, serine, threonine, cysteine, asparagine and glutamine.

2. The production method according to claim 1, wherein, the isocyanate silane comprises one or more of α-isocyanatomethyltrimethoxysilane, α-isocyanatomethyltriethoxysilane, γ-isocyanatopropyltrimethoxysilane and γ-isocyanatopropyltriethoxysilane; and / or, a molar ratio of the water-soluble amino acid to the isocyanate silane is 1: (1-1.2).

3. The production method according to claim 1, wherein, the water-soluble lithium salt comprises one or more of lithium chloride, lithium bromide and lithium nitrate; and / or, the water-soluble aluminum salt comprises one or more of aluminum chloride, aluminum bromide and aluminum nitrate.

4. The production method according to claim 1, wherein the alkaline solution comprises one or more of sodium hydroxide, potassium hydroxide and ammonia.

5. The production method according to claim 1, wherein a molar ratio of the water-soluble aluminum salt to the silane amino acid is 2: (0.04-0.15) ; and / or, a molar ratio of the water-soluble lithium salt to the water-soluble aluminum salt is (0.9-2) :

2.

6. The production method according to claim 1, wherein a temperature of the co-precipitation reaction is 60-90℃; and / or, an end-point pH of the co-precipitation reaction is 4.5-5.

5.

7. The production method according to claim 1, wherein the aging is performed under stirring; and / or, a temperature of the aging is 60-90℃; and / or, a time of the aging is 0.5-3h.

8. The production method according to claim 1, wherein the second mixture is aged to obtain a third mixture; the third mixture is filtered, washed with water and dried to obtain the lithium adsorbent. 9.A lithium adsorbent prepared by the method according to any one of claims 1 to 8. 10.Use of the lithium adsorbent prepared by the method according to any one of claims 1 to 8 in extracting lithium from a salt lake.

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