A lithium-aluminum layered double hydroxide adsorbent regeneration method based on lithium-containing eutectic solvent

Abstract

This invention relates to the field of adsorbent regeneration technology, specifically to a method for regenerating lithium-aluminum layered double hydroxide adsorbents based on a lithium-containing eutectic solvent. The method involves mixing structurally deactivated lithium-aluminum layered double hydroxide adsorbents with a lithium-containing eutectic regeneration solution, regenerating them under heating conditions, and obtaining the regenerated lithium-aluminum layered double hydroxide adsorbent after solid-liquid separation. The lithium-containing eutectic regeneration solution is obtained by mixing lithium salt with a hydrogen bond donor, a hydrogen bond acceptor, and water. This invention utilizes the lithium-containing eutectic regeneration solution to provide a high-activity lithium source and a special solvation environment, achieving the transformation of the deactivated adsorbent from a lithium-deficient / collapsed structure to a Li / Al-LDH active structure under mild conditions. It has the advantages of high regeneration efficiency, mild conditions, environmental friendliness, and simple operation; the lithium adsorption capacity recovery rate of the regenerated adsorbent can reach over 90%.

Description

Technical Field

[0001] This invention relates to the field of adsorption material regeneration technology, specifically to a method for regenerating lithium-aluminum layered double hydroxide adsorbents based on lithium-containing eutectic solvents. Background Technology

[0002] Lithium-aluminum layered double hydroxides (Li / Al-LDH) are based on the octahedral structure of aluminum hydroxide, with lithium ions filling the cavities within the octahedrons and other anions inserted into the interlayer spaces to balance the charge. The host and guest atoms are bonded by hydrogen bonds, electrostatic forces, and van der Waals forces. This unique structure gives Li / Al-LDH adjustable interlayer spacing, a large specific surface area, and high ion exchange capacity. It also boasts advantages such as simple preparation, low cost, and non-toxicity, and is currently widely used in lithium extraction from salt lakes and wastewater treatment.

[0003] In practical applications of Li / Al-LDH adsorbents, excessive release of lithium ions from the octahedral cavities of aluminum hydroxide during adsorption-desorption cycles can lead to structural deactivation of the adsorbent, resulting in significant material waste and increased costs. This deactivation manifests as a decrease in the Li / Al ratio, weakening of the Li / Al-LDH crystal phase, and partial or complete transformation to Gibbsite / Bayerite / Al(OH)3, which is fundamentally different from simple pore blockage.

[0004] To address the structural deactivation problem of Li / Al-LDH adsorbents, patent application CN112691654A discloses a one-step regeneration method for lithium aluminum salt adsorbents. This method involves mixing the deactivated lithium aluminum salt adsorbent with an organic solvent, ultrasonically dispersing it, vacuum drying it, and then impregnating it with a regenerating agent for regeneration. The organic solvent is at least one selected from methanol, ethanol, acetic acid, and acetone; the regenerating agent is a lithium salt solution or a mixed solution of lithium salt and alkali metal salt. While this method achieves regeneration, the use of organic solvents easily leads to pollution and waste, and the use of other alkali metal salts in the process can easily contaminate the adsorbent, resulting in an impure crystalline phase.

[0005] Patent application CN106140121A discloses a regeneration method for restoring the performance of aluminum salt lithium adsorbent. It uses an acidic solution with a pH of 2 to 6 as the first regeneration liquid and a lithium-containing system with a pH of 8 to 11 as the second regeneration liquid for regeneration. This method belongs to a dual-liquid switching restoration process, and the regeneration process is relatively complex.

[0006] Patent application CN115814775B discloses a regeneration method for a lithium-aluminum layered double hydroxide adsorbent, which employs an aqueous solution atmospheric pressure sealed aging process. This method involves mixing the deactivated adsorbent with a lithium source for regeneration and deionized water. Although the steps are simple, the ordinary aqueous solution system has limited ability to repair structural deactivation, and the regeneration efficiency needs to be improved. Summary of the Invention

[0007] To address the above problems, this invention provides a method for regenerating lithium-aluminum layered double hydroxide adsorbents based on a lithium-containing eutectic solvent. Using a lithium-containing eutectic regeneration solution as the regeneration medium, the structure of lithium-aluminum layered double hydroxide adsorbents that have become structurally deactivated due to excessive lithium ion release is restored and their performance recovered under mild conditions. The lithium-containing eutectic regeneration solution is a low-melting-point liquid system formed by lithium salt, hydrogen bond donor, hydrogen bond acceptor, and water. Its high lithium activity and unique solvation environment promote the migration and re-intercalation of lithium ions to the surface and interior of the deactivated adsorbent, while simultaneously inducing local dissolution, rearrangement, and layered reconstruction of the gibbersite / Al(OH)3 phase, achieving a transformation from a lithium-deficient collapsed structure to a Li / Al-LDH structure. This method requires no organic solvent pretreatment, no two-liquid switching, and can be implemented under normal pressure. It has the advantages of simple process flow, high regeneration efficiency, low equipment requirements, and environmental friendliness, and is suitable for the regeneration and repair of powdered, granular, and column-packed Li / Al-LDH adsorbents.

[0008] To achieve the above objectives, the technical solution of the present invention is as follows.

[0009] This invention provides a method for regenerating a lithium-aluminum layered double hydroxide adsorbent based on a lithium-containing eutectic solvent, comprising the following steps: The deactivated lithium-aluminum layered double hydroxide adsorbent is mixed with a lithium-containing eutectic regeneration solution and regenerated under atmospheric pressure heating or microwave-assisted heating. After solid-liquid separation, the regenerated lithium-aluminum layered double hydroxide adsorbent is obtained. The atmospheric pressure heating regeneration temperature is 40℃~120℃, and the regeneration time is 2min~12h. The microwave-assisted heating microwave power is 100W~1000W, and the microwave treatment time is 0.5min~60min. Optionally, after microwave treatment, the temperature is kept at 40℃~100℃ for 1min~6h. The lithium-containing eutectic regeneration solution is a mixture of lithium salt, hydrogen bond donor, hydrogen bond acceptor, and water, and the water content of the lithium-containing eutectic regeneration solution is 1wt%~25wt%. The hydrogen bond donor is an aqueous hydrogen bond donor.

[0010] Preferably, the lithium salt is selected from one or more of lithium water, lithium chloride, lithium fluoride, lithium bromide, lithium iodide, lithium nitrate, lithium acetate, and lithium hydroxide; the hydrogen bond donor is selected from water, or one or more of ethylene glycol, glycerol, urea, acetamide, and thiourea mixed with water; the hydrogen bond acceptor is selected from one or more of choline chloride, urea, acetamide, and thiourea; wherein urea, acetamide, and thiourea can simultaneously serve as hydrogen bond donors and hydrogen bond acceptors.

[0011] Preferably, the lithium-containing eutectic regenerated solution is selected from one or more of the following systems: urea-lithium chloride hydrate system, choline chloride-lithium chloride hydrate system, and choline chloride-urea-lithium chloride hydrate system. The urea-lithium chloride hydrate system is a mixture of lithium chloride, urea, and water; the choline chloride-lithium chloride hydrate system is a mixture of lithium chloride, choline chloride, and water; and the choline chloride-urea-lithium chloride hydrate system is a mixture of lithium chloride, choline chloride, urea, and water.

[0012] Preferably, in the choline chloride-lithium chloride hydrate system, choline chloride acts as a hydrogen bond acceptor, and water in the lithium chloride hydrate acts as a hydrogen bond donor.

[0013] Preferably, in the lithium-containing eutectic regeneration solution, the ratio of the molar amount of lithium salt to the total molar amount of hydrogen bond donors and hydrogen bond acceptors is 1:0.1 to 10; and the water content of the lithium-containing eutectic regeneration solution is 0.5 wt% to 40 wt%.

[0014] Preferably, in the lithium-containing eutectic regeneration solution, the molar ratio of the lithium salt to the total molar ratio of the hydrogen bond donor and the hydrogen bond acceptor is 1:0.1 to 6.

[0015] Preferably, the ratio of the deactivated lithium-aluminum layered double hydroxide adsorbent to the lithium-containing eutectic regeneration solution is 1g:1mL~30mL.

[0016] Preferably, the ratio of the deactivated lithium-aluminum layered double hydroxide adsorbent to the lithium-containing eutectic regeneration solution is 1g:3mL~20mL.

[0017] Preferably, the ambient pressure heating temperature is 50℃~100℃, and the time is 2min~8h; the microwave-assisted heating microwave power is 200W~800W, and the microwave time is 1min~30min.

[0018] Preferably, the molar ratio of Li to Al in the deactivated lithium-aluminum layered double hydroxide adsorbent is 1:4 to 5; and the molar ratio of Li to Al in the regenerated lithium-aluminum layered double hydroxide adsorbent is 1:2 to 2.2.

[0019] Preferably, the regeneration process is carried out using one or more of the following methods: stirring impregnation, static impregnation, circulating impregnation, and flowing contact.

[0020] This invention uses a lithium-containing eutectic solvent (DES) instead of traditional saline aqueous solutions as the regeneration medium. Based on the unique mechanism of DES in the regeneration process of aluminum-based lithium adsorbents, it achieves synergistic regulation of "stabilizing the framework, opening pores, and regenerating active sites." DES has low water activity, which can significantly weaken the framework damage and inert phase transformation caused by hydrolysis during regeneration, thus helping to maintain the structural integrity and cycle stability of aluminum-based adsorbents. Metal ions in DES are in a controllable coordination environment, which can promote the regeneration of Li through specific coordination and ion activity regulation. + The desorption-re-intercalation equilibrium and active site reconstruction of DES improve regeneration efficiency. DES combines dissolution, complexation, and interface regulation, achieving synergistic enhancement of pore-blocking species removal, pore reopening, and local structural remodeling under milder conditions, avoiding particle breakage, crystal phase collapse, and performance degradation caused by traditional strong acid / base regeneration. DES has advantages such as low vapor pressure, near-non-volatile nature, and high thermal stability, effectively avoiding system composition changes and environmental pollution problems caused by volatilization, while reducing dependence on special equipment conditions such as sealed pressurized containers.

[0021] In lithium-containing eutectic regeneration solutions, the high-activity lithium source and unique solvation environment facilitate the migration and reintercalation of lithium ions to the surface and interior of the deactivated adsorbent. Simultaneously, the localized structure composed of lithium salt, water, and hydrogen bond donors / acceptors promotes local dissolution, rearrangement, and layered reconstruction of the Gibbsite / Bayerite / Al(OH)3 phase. Under atmospheric pressure or microwave fields, these processes are further enhanced, thereby achieving a transformation from a lithium-deficient / collapsed structure to a lithium-adsorbing Li / Al-LDH structure.

[0022] The beneficial effects of this invention are: 1. This invention precisely targets the structural deactivation caused by over-lithiation. Through the re-intercalation of a high-activity lithium source and phase reconstruction under a special solvation environment, it achieves the directional transformation of the gibbersite / Al(OH)3 phase towards the Li / Al-LDH structure. The regenerated adsorbent exhibits high crystal phase purity and good structural integrity. This invention is applicable to the regeneration and repair of powdered, granular, and column-packed Li / Al-LDH adsorbents, has low equipment requirements, and is highly adaptable to industrial implementation.

[0023] 2. Compared to traditional organic solvent regeneration methods, this invention avoids the use of organic solvents such as methanol, ethanol, acetic acid, and acetone, making it environmentally friendly. Furthermore, the regenerated liquid has a low vapor pressure, is recyclable, and offers high process safety. Compared to two-liquid switching regeneration processes, this invention employs a one-step regeneration process, directly reacting the deactivated adsorbent with a lithium-containing eutectic regeneration liquid to achieve structural recovery. This is simple to operate and requires no multiple steps. Compared to conventional aqueous solution regeneration under normal pressure and sealed aging conditions, this invention achieves highly efficient regeneration under normal pressure, mild temperature, or microwave-assisted conditions, significantly improving regeneration efficiency. Microwave assistance can further shorten the regeneration time. Attached Figure Description

[0024] Figure 1 XRD patterns of aluminum-based adsorbent samples before and after regeneration.

[0025] Figure 2 SEM images of aluminum-based adsorbent samples before and after regeneration are shown. Among them, (a) is the new adsorbent; (b) is the exhausted adsorbent; (c) is the adsorbent regenerated in Example 1; (d) is the adsorbent regenerated in Example 2; and (e) is the new adsorbent regenerated in Example 3. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0027] Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] The technical solution of the present invention will be further described below through specific embodiments.

[0029] This invention addresses the structural deactivation problem of lithium / aluminum layered double hydroxide (Li / Al-LDH) adsorbents caused by excessive lithium ion release during adsorption-desorption cycles. It proposes a repair strategy using a lithium-containing eutectic regeneration solution as the regeneration medium. The core concept lies in utilizing the high-activity lithium source in a eutectic solvent (DES) or molten salt hydrate system, a unique solvation environment, and controllable water activity to synergistically promote the local dissolution of the lithium-deficient phase (gibbsite / Al(OH)3) in the deactivated adsorbent, lithium ion re-intercalation, and layered structure reconstruction, thereby achieving a transformation from an inactive phase to an active Li / Al-LDH structure.

[0030] Specifically, the lithium salt in the lithium-containing eutectic regenerated solution provides a high concentration of lithium ions, and the local network constructed by hydrogen bond donors / acceptors regulates ion transport channels and interfacial reactivity, while the presence of an appropriate amount of water balances the system's solubility and structural stability. Under atmospheric pressure heating or microwave-assisted conditions, the regenerated solution comes into full contact with the deactivated adsorbent, allowing lithium ions to diffuse into the adsorbent and reoccupy interlayer positions. Simultaneously, the gibbsite / Al(OH)3 phase undergoes local dissolution and rearrangement under the unique solvation effect of the regenerated solution, gradually restoring the crystal phase structure of the layered double hydroxide and its lithium adsorption activity.

[0031] The following steps or conditions may be adjusted according to actual needs, and are not limited to the specific methods described in the embodiments: The composition of the lithium-containing eutectic regenerated liquid is not limited to the urea-LiCl·H2O system, choline chloride-LiCl·H2O system and choline chloride-urea-LiCl·H2O ternary system listed in the examples. Other deep eutectic solvents formed by lithium salts, hydrogen bond donors, hydrogen bond acceptors and water, aqueous deep eutectic systems, eutectic ionic liquids or molten salt hydrate systems are also applicable.

[0032] The lithium salt is not limited to lithium chloride hydrate, lithium chloride, lithium nitrate, lithium acetate, and lithium hydroxide; other lithium-containing inorganic or organic salts may also be used.

[0033] The hydrogen bond donors are not limited to urea, ethylene glycol, glycerol, acetamide, and thiourea; other compounds containing hydroxyl, amino, or amide groups may also be used.

[0034] The hydrogen bond acceptor is not limited to choline chloride, urea, acetamide, or thiourea; other quaternary ammonium salts, zwitterionic compounds, or organic molecules containing lone pairs of electrons may also be used.

[0035] The heating method is not limited to atmospheric pressure heating and microwave-assisted heating. Other heating methods that can provide heat energy, such as oil bath heating, electric heating mantle heating, infrared heating, and ultrasonic-assisted heating, are also applicable.

[0036] The regeneration process is not limited to stirring impregnation, static impregnation, circulating impregnation, or flow contact. Other processing methods that can achieve sufficient solid-liquid contact, such as spraying and fluidized bed treatment, are also applicable.

[0037] The washing solution is not limited to deionized water or ethanol / water mixture; other solvents that can effectively remove residual regeneration solution and do not react adversely with the adsorbent are also applicable.

[0038] The solid-liquid separation method is not limited to centrifugal separation and filtration separation; other conventional solid-liquid separation methods such as vacuum filtration and sedimentation separation are also applicable.

[0039] The drying method is not limited to vacuum drying and oven drying. Other drying methods that can effectively remove moisture and maintain the stability of the adsorbent structure, such as freeze drying and spray drying, are also applicable.

[0040] In the following embodiments, unless otherwise specified, the methods described are conventional methods; and unless otherwise specified, the reagents and materials described are commercially available.

[0041] Example 1 A method for regenerating a lithium-aluminum layered double hydroxide adsorbent based on a lithium-containing eutectic solvent includes the following steps: S1. Weigh 9.97g of urea and 10.03g of lithium chloride monohydrate (LiCl·H2O) respectively, grind and mix them, and add them to a 100mL round-bottom flask. Proceed to 75℃ and keep warm for 1h. Stir until a uniform and transparent liquid is formed to obtain a urea-based lithium eutectic regeneration solution, denoted as UL-1 (the molar ratio of urea to LiCl·H2O is about 1:1, and the water content is about 14.9wt%).

[0042] S2. Weigh 1.67g of structurally deactivated lithium-aluminum layered double hydroxide adsorbent and mix it with the urea-based lithium eutectic regeneration solution UL-1 prepared in S1 (solid-liquid ratio 1:10g / mL). Control the stirring speed to 120r / min, raise the system temperature to 90℃ and keep it at that temperature for 5min to complete the regeneration.

[0043] S3. After the S2 treatment, the sample is centrifuged (4000 r / min, 5 min), washed 3 times with deionized water until the filtrate is neutral (pH=7.0), and vacuum dried at 60℃ (-0.1 MPa) for 2 h to obtain the regenerated lithium aluminum layered double hydroxide adsorbent.

[0044] Example 2 A method for regenerating a lithium-aluminum layered double hydroxide adsorbent based on a lithium-containing eutectic solvent includes the following steps: S1. Weigh 10.72g of choline chloride and 9.28g of lithium chloride monohydrate, grind and mix them, and add them to a 100mL round-bottom flask. Proceed to 95℃ and keep warm for 2 hours. Stir until a uniform and transparent liquid is formed to obtain a choline-based lithium eutectic regeneration solution, denoted as ChL-1 (the molar ratio of choline chloride to LiCl·H2O is approximately 1:2, and the water content is approximately 13.8wt%).

[0045] S2. Weigh 1.67g of structurally deactivated lithium-aluminum layered double hydroxide adsorbent and mix it with the lithium-containing eutectic regeneration solution ChL-1 prepared in step S1 (solid-liquid ratio 1:10g / mL). Control the stirring speed to 210r / min, raise the system temperature to 90℃ and keep it at that temperature for 20min to complete the regeneration.

[0046] S3. Following the same step S3 as in Example 1, the regenerated lithium-aluminum layered double hydroxide adsorbent is obtained.

[0047] Example 3 A method for regenerating a lithium-aluminum layered double hydroxide adsorbent based on a lithium-containing eutectic solvent includes the following steps: S1. Weigh 6.65g of urea, 3.57g of choline chloride, and 9.78g of lithium chloride monohydrate, grind and mix them, and add them to a 100mL round-bottom flask. Proceed to 85℃ and keep warm for 2 hours to obtain a choline-based lithium eutectic regeneration solution, denoted as UChL-1 (the molar ratio of urea, choline chloride, and LiCl·H2O is approximately 1:2:1, and the water content is approximately 14.5wt%).

[0048] S2. Weigh 1.67g of structurally deactivated lithium aluminum layered double hydroxide adsorbent and mix it with the lithium-containing eutectic regeneration solution UChL-1 prepared in S1. Control the stirring speed to 140r / min, raise the system temperature to 90℃ and keep it at that temperature for 10min to complete the regeneration. S3. Following the same step S3 as in Example 1, the regenerated lithium-aluminum layered double hydroxide adsorbent is obtained.

[0049] The exhausted adsorbent, the new adsorbent, and the lithium-aluminum layered double hydroxide adsorbent regenerated by the methods described in Examples 1 to 3 were subjected to XRD phase analysis. The results are shown in the figure. Figure 1 As shown. By Figure 1 It can be seen that obvious Al(OH)3 impurity diffraction peaks appeared in the deactivated adsorbent, indicating that the adsorbent underwent structural transformation during the deactivation process. The characteristic Al(OH)3 peaks of the lithium aluminum layered double hydroxide adsorbent regenerated by the methods described in Examples 1 to 3 were significantly weakened or even basically disappeared, indicating that the regeneration method can effectively eliminate the impurity phases generated during the deactivation process, promote the structural recovery of the adsorbent, and has a good regeneration effect.

[0050] The morphology of the failed adsorbent, the new adsorbent, and the lithium-aluminum layered double hydroxide adsorbent regenerated by the methods described in Examples 1 to 3 were analyzed by SEM. The results are shown in the figure. Figure 2 As shown. By Figure 2It can be seen that the surface of the deactivated adsorbent showed obvious fragmented and damaged structures, indicating that the adsorbent underwent significant morphological and structural deterioration during deactivation, resulting in the destruction of its original layered structure and particle integrity. After regeneration using the methods described in Examples 1 to 3, the regenerated lithium-aluminum layered double hydroxide adsorbent had a regular overall morphology and intact structure, which was basically consistent with the newly prepared adsorbent. The results show that the regeneration method described in this invention can effectively repair the fragmented and damaged structures formed during deactivation, promote the restoration of the adsorbent's morphology and layered structure, and has a significant regeneration and repair effect.

[0051] The regenerated lithium-aluminum layered double hydroxide adsorbents obtained in Examples 1-3, as well as the newly prepared adsorbent and the depleted adsorbent, were weighed out at 1.0 g each and added to 30 mL of a certain chloride-type salt lake brine (Li). + The concentration was 0.231 g / L, Mg 2+ The lithium ion concentration was 114.3 g / L, and the adsorption was carried out at room temperature with shaking for 8 h. After the adsorption was completed, the lithium ion concentration in the solution was measured, and the adsorption capacity of each adsorbent for lithium in a certain chloride-type salt lake brine was calculated accordingly. The results are shown in Table 1.

[0052] Table 1. Changes in the adsorption capacity of aluminum-based adsorbent samples for lithium in brine before and after regeneration. Note: "-" indicates no data. New adsorbent refers to lithium-aluminum layered double hydroxide adsorbent that has not undergone adsorption-desorption cycles and is in its initial activated state. Deactivated adsorbent refers to structurally deactivated lithium-aluminum layered double hydroxide adsorbent.

[0053] As shown in Table 1, compared with the freshly prepared adsorbent, the adsorption capacity of the deactivated adsorbent for lithium decreased by about 45%, indicating that its effective adsorption performance was significantly reduced. However, the lithium-aluminum layered double hydroxide adsorbent regenerated by the methods described in Examples 1 to 3 can restore the effective adsorption capacity for lithium to 99.58% to 99.99% of the initial capacity, indicating that the regeneration method described in this invention can significantly restore the adsorption performance of the deactivated aluminum-based adsorbent, and the regeneration effect is very significant.

[0054] The lithium and aluminum content of the newly prepared adsorbent, the depleted adsorbent, and the regenerated lithium-aluminum layered double hydroxide adsorbent obtained in Examples 1 to 3 were tested, and the corresponding Li / Al molar ratios were calculated. The results are shown in Table 2.

[0055] Table 2. Changes in lithium / aluminum ratio of aluminum-based adsorbent samples before and after regeneration. Table 2 shows that the Li to Al molar ratio in the freshly prepared adsorbent is 1:2.02, while the Li to Al molar ratio in the deactivated adsorbent is 1:4.12. This indicates that the active lithium sites in the adsorbent are significantly reduced and the structural composition changes significantly during the deactivation process. The lithium-aluminum layered double hydroxide adsorbent regenerated using the methods described in Examples 1-3 has a Li to Al molar ratio restored to 1:2.02-2.11, close to the level of the freshly prepared adsorbent. This demonstrates that the regeneration method described in this invention can effectively restore the compositional characteristics and active structure of the deactivated aluminum-based adsorbent, achieving good regeneration results.

[0056] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for regenerating a lithium-aluminum layered double hydroxide adsorbent based on a lithium-containing eutectic solvent, characterized in that, Includes the following steps: The deactivated lithium-aluminum layered double hydroxide adsorbent was mixed with a lithium-containing eutectic regeneration solution and regenerated under normal pressure heating or microwave-assisted heating conditions. After solid-liquid separation, the regenerated lithium-aluminum layered double hydroxide adsorbent was obtained. The conditions for atmospheric pressure heating are: regeneration temperature of 40℃~120℃, and regeneration time of 2min~12h; The conditions for microwave-assisted heating are: microwave power of 100W to 1000W, microwave processing time of 0.5min to 60min, and temperature of 40℃ to 100℃. The lithium-containing eutectic regenerated solution is obtained by mixing lithium salt, hydrogen bond donor and hydrogen bond acceptor, and the water content of the lithium-containing eutectic regenerated solution is 1wt% to 25wt%. The hydrogen bond donor is a water-containing hydrogen bond donor.

2. The method for regenerating lithium-aluminum layered double hydroxide adsorbent based on a lithium-containing eutectic solvent according to claim 1, characterized in that, The lithium salt is selected from one or more of lithium chloride hydrate, lithium chloride, lithium fluoride, lithium bromide, lithium iodide, lithium nitrate, lithium acetate, and lithium hydroxide; The hydrogen bond donor is selected from water, or one or more of ethylene glycol, glycerol, urea, acetamide and thiourea mixed with water; The hydrogen bond acceptor is selected from one or more of choline chloride, urea, acetamide, and thiourea.

3. The method for regenerating lithium-aluminum layered double hydroxide adsorbent based on a lithium-containing eutectic solvent according to claim 2, characterized in that, The lithium-containing eutectic regenerated solution is selected from one or more of the following systems: urea-lithium chloride hydrate system, choline chloride-lithium chloride hydrate system, and choline chloride-urea-lithium chloride hydrate system. The urea-lithium chloride hydrate system is a mixture of lithium chloride, urea, and water. The choline chloride-lithium chloride hydrate system is a mixture of lithium chloride, choline chloride, and water; The choline chloride-urea-lithium chloride hydrate system is a mixture of lithium chloride, choline chloride, urea and water.

4. The method for regenerating lithium-aluminum layered double hydroxide adsorbent based on a lithium-containing eutectic solvent according to claim 1, characterized in that, In the lithium-containing eutectic regenerated solution, the ratio of the molar amount of the lithium salt to the total molar amount of the hydrogen bond donor and the hydrogen bond acceptor is 1:0.1 to 10. The water content of the lithium-containing eutectic regenerated solution is 0.5wt% to 40wt%.

5. The method for regenerating a lithium-aluminum layered double hydroxide adsorbent based on a lithium-containing eutectic solvent according to claim 1, characterized in that, In the lithium-containing eutectic regenerated solution, the ratio of the molar amount of the lithium salt to the total molar amount of the hydrogen bond donor and the hydrogen bond acceptor is 1:0.1 to 6.

6. The method for regenerating a lithium-aluminum layered double hydroxide adsorbent based on a lithium-containing eutectic solvent according to claim 1, characterized in that, The ratio of the deactivated lithium-aluminum layered double hydroxide adsorbent to the lithium-containing eutectic regeneration solution is 1g:1mL~30mL.

7. The method for regenerating a lithium-aluminum layered double hydroxide adsorbent based on a lithium-containing eutectic solvent according to claim 1, characterized in that, The molar ratio of Li to Al in the deactivated lithium-aluminum layered double hydroxide adsorbent is 1:4-5; the molar ratio of Li to Al in the regenerated lithium-aluminum layered double hydroxide adsorbent is 1:2-2.2.

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