Aluminum hydroxide-based adsorbent materials, their preparation methods, and their applications in the selective adsorption of lithium ions.

Abstract

This invention relates to an aluminum hydroxide-based adsorbent material, its preparation method, and its application in the selective adsorption of lithium ions, belonging to the field of adsorbent material technology. It solves the problems of existing lithium ion adsorbent materials, such as complex preparation processes, high costs, environmental pollution, low adsorption performance, poor selectivity for lithium ions, and unsuitability for high magnesium-to-lithium ratio brine. The preparation method of this invention involves first mixing an aluminum salt solution and a urea solution uniformly at room temperature, magnetically stirring at 30-90°C, allowing it to stand, filtering, and drying to obtain x-UA; then, at room temperature, performing lithium ion saturation adsorption of x-UA in a lithium chloride solution, filtering, and drying to obtain Li-x-UA; finally, washing Li-x-UA with a detergent, filtering, and drying to obtain the adsorbent material. This adsorbent material can achieve highly selective extraction of lithium ions in high magnesium-to-lithium ratio brine.

Description

Technical Field

[0001] This invention belongs to the field of adsorption material technology, specifically relating to an aluminum hydroxide-based adsorption material, its preparation method, and its application in the selective adsorption of lithium ions, particularly the application of this aluminum hydroxide-based adsorption material in the selective extraction of lithium ions from salt lake brines with a high magnesium-to-lithium ratio. Background Technology

[0002] Against the backdrop of rapid development in the new energy industry, the demand for lithium continues to rise. Most lithium salt production still relies on lithium ore extraction, but the ore-based lithium extraction method is costly, economically unsustainable, and relatively weak in market competitiveness.

[0003] The chemical composition of salt lake brines is extremely complex, and its composition varies significantly due to regional differences. Therefore, different production processes must be adopted for different salt lakes. This characteristic has largely restricted the large-scale development of lithium resources in salt lakes. Currently, research on lithium extraction technology from salt lake brines at home and abroad mainly focuses on evaporation crystallization, precipitation, solvent extraction, calcination leaching, and adsorption methods.

[0004] Evaporation crystallization is an extraction method that gradually evaporates brine through natural sun exposure, causing lithium salts to crystallize and precipitate. This process is mainly suitable for areas with abundant sunshine and high evaporation rates, with the Zabuye Salt Lake being a typical example, which has a low magnesium-to-lithium ratio (Mg / Li < 0.1).

[0005] Precipitation methods utilize solar energy to evaporate and concentrate brine in salt lakes through a series of stages. Once lithium ions reach a certain concentration, impurities such as boron, calcium, and magnesium are removed sequentially. A precipitant or salting-out agent is then added to precipitate lithium as lithium salts. Among these methods, carbonate precipitation offers advantages such as ease of operation, energy saving, environmental friendliness, and suitability for industrial application, but it suffers from a longer process and lower lithium recovery rates. While aluminate and aluminum salt precipitation methods offer higher lithium recovery rates and product purity, they are primarily suitable for salt lake brine resources with high magnesium-to-lithium ratios and consume significant amounts of freshwater and sodium carbonate, resulting in high energy consumption.

[0006] Solvent extraction for lithium extraction leverages the difference in partition coefficients of lithium ions in two immiscible solvent phases to achieve the separation, purification, and enrichment of lithium ions. This technology boasts high extraction efficiency and is suitable for brine systems with high magnesium-to-lithium ratios in salt lakes. However, it also has several limitations, including the high cost and susceptibility to loss of organic extractants, significant potential environmental risks, and the high requirements for equipment materials and operational stability due to the large volume of brine to be processed, resulting in high overall costs for industrial applications.

[0007] The calcination-leaching method uses brine after boron extraction as the research object. A mixed salt containing MgCl₂•₆H₂O and LiCl is obtained through evaporation and concentration. Based on the characteristic that MgCl₂•₆H₂O decomposes into magnesium oxide and hydrogen chloride gas above 550℃, while LiCl remains stable at this temperature, the mixed salt is calcined at high temperature, followed by leaching with water to allow soluble LiCl to enter the liquid phase. The resulting solution is further purified and concentrated, and then sodium carbonate is added to precipitate lithium carbonate. This process is suitable for salt lake resources with high magnesium and lithium content, but its main drawback is that the HCl gas released during the calcination of MgCl₂•₆H₂O is not only highly corrosive to equipment but also causes significant environmental pollution.

[0008] Lithium extraction via adsorption utilizes materials with selective lithium-ion adsorption capabilities to separate lithium ions from brine, and then achieves effective separation of lithium from other impurity ions through acid elution. Currently, widely studied adsorbents include amorphous hydroxide adsorbents, layered adsorbents, lithium aluminum salt adsorbents, and ion-sieve oxide adsorbents. However, in high magnesium-to-lithium ratio salt lakes, the separation of magnesium and lithium is challenging, and traditional adsorption lithium extraction technologies generally suffer from low separation efficiency and insufficient selectivity, limiting their practical application.

[0009] In the prior art, a Li / Al layered double hydroxide crystal structure and Li + Efficient regeneration of adsorption capacity (Materials Letters, 340 (2023), 134159): A one-step co-precipitation method was used to synthesize lithium aluminum layered double hydroxides LDHs-A, LDHs-B, and LDHs-C for adsorbing lithium from salt lakes. The specific preparation scheme is as follows: Lithium / aluminum-hydrotalcite was synthesized by co-precipitation according to Heidari's method, denoted as LDHs-A. 5g of LDHs-A was dispersed in 750mL of deionized water and washed at 75℃ for 2 hours. Then, it was filtered, washed until the filtrate was neutral, and dried in a drying oven. The resulting product was denoted as LDHs-B. Subsequently, 5g of LDHs-B and 2.5g of lithium chloride were added to 250mL of deionized water and soaked at room temperature for 30 minutes to achieve ion pre-exchange. Then, the pH of the mixed solution was adjusted to 8 and aged at 60℃ for 4 hours. After the reaction was completed, the final product was obtained by filtration, thorough washing, and drying, denoted as LDHs-C. However, the maximum adsorption capacity of lithium ions for LDHs-A, LDHs-B, and LDHs-C is only 6.69 mg·g⁻¹, respectively. -1 3.16 mg·g -1 and 5.85 mg·g -1The adsorption performance is low and needs further improvement; moreover, in a simulated brine system with equal concentrations of lithium ions, magnesium ions, potassium ions, and sodium ions, the separation coefficient and distribution coefficient of the above materials for lithium ions are both at a low level, indicating that their selective separation performance for lithium ions still needs to be improved.

[0010] In the prior art, Chinese invention patent application CN106430254A discloses a method for extracting lithium from salt lake brine. This method involves calcining kaolin and acid leaching to obtain an aluminum leaching solution and a silica-alumina based adsorbent. The aluminum leaching solution is used to initially precipitate lithium in the brine. Subsequently, the silica-alumina based adsorbent is used to enrich the residual lithium in the brine after precipitation, followed by desorption for secondary lithium precipitation. Finally, the aluminum-lithium precipitates obtained from the two precipitation processes are separated to obtain a relatively homogeneous lithium solution. However, the lithium ion adsorption capacity of the adsorbents obtained in both processes is only 2.3 mg·g. -1 and 2.93 mg·g -1 The adsorption performance is relatively low and needs further improvement. Furthermore, the brine used in this lithium extraction process is a simulated brine from Damxung Co Salt Lake, with a Mg / Li ratio of 1, significantly lower than that of the Qarhan Salt Lake, thus making lithium ion extraction relatively easier.

[0011] In the prior art, a study on the preparation and lithium extraction performance of a functionalized covalent organic framework adsorbent was disclosed (Master's thesis, Shihezi University, 2024). A series of sulfonated covalent organic framework (S-COF) adsorbents were synthesized by adjusting the concentration of the catalyst through a hydrothermal reaction. However, the adsorption of lithium from salt lake brine by functionalized covalent organic framework adsorbents has the following drawbacks: 1) The material preparation process is complex and costly, resulting in poor industrial applicability; 2) The Mg / Li ratio of the simulated salt lake brine used in the lithium extraction process is 1, which is significantly lower than that of the Qarhan Salt Lake, thus making lithium ion extraction relatively easier; 3) In the simulated salt lake brine, the adsorbent has low selectivity for lithium ions compared to magnesium, potassium, sodium, and calcium ions, and further improvement is needed. Summary of the Invention

[0012] This invention addresses the problems of complex preparation processes, high costs, environmental pollution, low adsorption performance, poor selectivity for lithium ions, and unsuitability for high magnesium-to-lithium ratio brine in existing lithium-ion adsorbent materials. It utilizes lithium ions as a template to prepare a porous lithium-ion adsorbent material with an aluminum hydroxide framework through ultra-uniform precipitation and freeze-drying techniques. This material achieves highly selective extraction of lithium ions in high magnesium-to-lithium ratio brine, with a lithium adsorption capacity as high as 23.18 mg / g at room temperature. -1 Furthermore, its adsorption capacity increases with increasing temperature, opening up a new path for lithium extraction technology from salt lakes.

[0013] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows.

[0014] In a first aspect, the present invention provides a method for preparing an aluminum hydroxide-based adsorbent material, comprising the following steps:

[0015] 1) Mix aluminum salt solution and urea solution evenly at room temperature, stir magnetically at 30℃-90℃, cool, let stand, vacuum filter, freeze dry the filter residue to obtain x-UA;

[0016] 2) At room temperature, x-UA was subjected to lithium-ion saturation adsorption in a lithium chloride solution. After vacuum filtration, the filter residue was freeze-dried to obtain Li-x-UA.

[0017] 3) Li-x-UA was washed with detergent, and after washing, it was vacuum filtered and the filter residue was vacuum dried to obtain aluminum hydroxide-based adsorbent (Li-templated-x-UA).

[0018] The detergent contains 0.1-1 mol·L⁻¹ -1 A mixture of ferric chloride hydrochloric acid solution, tributyl phosphate, and ethyl acetate in a mass ratio of 1:1 to 5:5;

[0019] Alternatively, the detergent contains 0.1-1 mol·L⁻¹ -1 A mixture of ferric chloride hydrochloric acid solution, carboxylic acid ionic liquid, and ethyl acetate in a mass ratio of 1:0.1-0.5:5, wherein the carboxylic acid ionic liquid is an ionic compound composed of an organic cation containing a hydroxyl group and a carboxylate anion.

[0020] Preferably, in step 1), the aluminum salt is one or more of aluminum chloride, aluminum sulfate, and aluminum nitrate.

[0021] Preferably, in step 1), the molar ratio of the aluminum salt to urea is 5:1 to 1:5.

[0022] Preferably, in step 1), the concentration of the aluminum salt solution is 0.1-1 mol·L⁻¹. -1 .

[0023] Preferably, in step 1), the concentration of the urea solution is 0.1-1 mol·L⁻¹. -1 .

[0024] Preferably, in step 1), the mixture is magnetically stirred at 30℃-90℃ for 1-2 days, cooled to room temperature, and left to stand for 2-10 hours.

[0025] Preferably, in step 2), the mass ratio of x-UA to lithium chloride is 1:1 to 1:3.

[0026] Preferably, in step 2), the concentration of the lithium chloride solution is 0.01-0.8 mol·L⁻¹. -1 .

[0027] Preferably, step 2), the process of saturating x-UA with lithium ions in lithium chloride solution, is as follows: mix x-UA with lithium chloride solution, stir magnetically for 1-2 days, and then age for 2-10 hours.

[0028] Preferably, in step 3), the washing process is as follows: soaking Li-x-UA in detergent for 4-6 hours, and then rinsing with detergent for 0.5-1 hours.

[0029] Preferably, in step 3), the carboxylic acid ionic liquid is one or more of 1-hydroxyethyl-3-methylimidazolium acetate, 1-hydroxyethyl-3-methylimidazolium carboxylate, and hydroxyethyltrimethylammonium acetate.

[0030] Preferably, in step 3), the temperature of the vacuum drying is 20-60°C.

[0031] Preferably, in step 3), the pH of the hydrochloric acid solution is 1.

[0032] Secondly, the present invention also provides an aluminum hydroxide-based adsorbent prepared by the above-mentioned method for preparing aluminum hydroxide-based adsorbent materials.

[0033] Thirdly, the present invention also provides the application of the above-mentioned aluminum hydroxide-based adsorbent material in the selective adsorption of lithium ions.

[0034] Preferably, the aluminum hydroxide-based adsorbent is used in the extraction of lithium ions from salt lake brine with a magnesium-to-lithium ratio >250.

[0035] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0036] The preparation method of the aluminum hydroxide-based adsorbent material of the present invention is simple, the raw materials are cheap and readily available, it is easy to promote in industry, and it is environmentally friendly and pollution-free.

[0037] The method for preparing the aluminum hydroxide-based adsorbent material of the present invention uses a lithium-ion detergent, which can effectively improve the elution rate of lithium ions, thereby increasing the adsorption capacity of the adsorbent material for lithium ions.

[0038] The aluminum hydroxide-based adsorbent of this invention exhibits a lithium adsorption capacity as high as 23.18 mg·g at room temperature. -1 Furthermore, its adsorption capacity increases with increasing temperature, far exceeding the adsorption capacity of various amorphous hydroxide adsorbents, layered adsorbents, and lithium aluminum salt adsorbents for lithium ions.

[0039] The aluminum hydroxide-based adsorbent of the present invention reacts with Li +Lithium adsorption selectivity was high in simulated salt lake brine containing multiple metal cations (magnesium, potassium, sodium, and calcium ions) at equal concentrations, with partition coefficients of each metal cation greater than 200.

[0040] The aluminum hydroxide-based adsorbent of this invention, when simulating the high magnesium-to-lithium ratio (Mg / Li > 250) brine of the Qarhan Salt Lake, still exhibits partition coefficients of all metal cations greater than 30, which is higher than that of various lithium-ion sieve-type oxide adsorbents currently available. Attached Figure Description

[0041] Figure 1 The diagram shows the process flow charts for preparing aluminum hydroxide-based adsorbent materials in Examples 1-10 and Comparative Examples 1-4 of the present invention, where x represents 140.

[0042] Figure 2 The Li-templated-140-UA prepared in Examples 1-10 of this invention adsorbs Li at different temperatures + The isotherms are fitted using the equations from (a) Langmuir, (b) Freundlich, (c) Temkin, and (d) Dubinin-Radushkevich, respectively. In the figure, C... e q represents the concentration at adsorption equilibrium. e To balance the adsorption amount, ε 2 This represents the square of the Polanyi potential.

[0043] Figure 3 The Li-templated-140-UA prepared in Examples 1-10 of this invention adsorbs Li at different temperatures + The kinetic curves are fitted by (a) pseudo-first-order and (b) pseudo-second-order kinetic equations, respectively. In the figures, t represents time, and q represents... t This represents the amount of adsorption at the corresponding time.

[0044] Figure 4 The graphs show the adsorption thermodynamics of Li-templated-140-UA prepared in Examples 1-10 of this invention (a) and the results of fitting the pseudo-first-order adsorption kinetic rate constants at different temperatures using the Arrhenius empirical formula (b). In the figures, T represents temperature, K... D (L) is the theoretical adsorption equilibrium constant, k1 is the first-order adsorption kinetic constant, A is the pre-factor, and E a As the activation energy, R 2 The correlation coefficient. Detailed Implementation

[0045] To further understand the present invention, preferred embodiments of the present invention are described below. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the scope of the claims of the present invention.

[0046] The method for preparing the aluminum hydroxide-based adsorbent material of the present invention includes the following steps:

[0047] 1) Mix aluminum salt solution and urea solution evenly at room temperature, stir magnetically at 30℃-90℃, cool, let stand, vacuum filter, freeze dry the filter residue to obtain x-UA;

[0048] 2) At room temperature, x-UA was subjected to lithium-ion saturation adsorption in a lithium chloride solution. After vacuum filtration, the filter residue was freeze-dried to obtain Li-x-UA.

[0049] 3) The Li-x-UA was washed with detergent, and then vacuum filtered. The filter residue was dried under vacuum to obtain aluminum hydroxide-based adsorbent (Li-templated-x-UA).

[0050] In this invention, the 'x' in x-UA, Li-x-UA, and Li-templated-x-UA is used to facilitate the labeling of different products. In the actual preparation process, 'x' can be the volume of urea solution used when the aluminum salt solution is 100 mL. For example, if 100 mL of aluminum salt solution and 140 mL of urea solution are used, 'x' is 140.

[0051] In step 1) of this invention, the preferred molar ratio of aluminum salt to urea is 5:1 to 1:5. For example, in some embodiments, the molar ratio of aluminum salt to urea is 5:1, 4:1, 3:1, 2:1, 1:1, 1:2, 1:3, 1:4, or 1:5.

[0052] In step 1) of this invention, the aluminum salt is preferably one or more of aluminum chloride, aluminum sulfate, and aluminum nitrate. The concentration of the aluminum salt solution is preferably 0.1-1 mol·L⁻¹. -1 For example, in some implementations, 0.1 mol·L⁻¹ is used. -1 0.2 mol·L -1 0.3 mol·L -1 0.4 mol·L -1 0.5 mol·L -1 0.6 mol·L -1 0.7 mol·L -1 0.8 mol·L -1 0.9 mol·L -1 1.0 mol·L -1 .

[0053] In step 1) of this invention, the concentration of the urea solution is preferably 0.1-1 mol·L⁻¹. -1 For example, in some implementations, 0.1 mol·L⁻¹ is used. -1 0.2 mol·L -1 0.3 mol·L -1 0.4 mol·L -1 0.5 mol·L -1 0.6 mol·L -1 0.7 mol·L -1 0.8 mol·L -1 0.9 mol·L -1 1.0 mol·L -1 .

[0054] In step 1) of this invention, magnetic stirring is preferably performed at 30℃-90℃ for 1-2 days, such as in some embodiments using 30℃, 40℃, 50℃, 60℃, 70℃, 80℃, or 90℃. Cooling to room temperature is preferred. Standing is preferred for 2-10 hours, such as in some embodiments using 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, or 10 hours.

[0055] In step 2) of this invention, the preferred mass ratio of x-UA to lithium chloride is 1:1 to 1:3. In some embodiments, ratios of 1:1, 1:2, and 1:3 are used.

[0056] In step 2) of this invention, the concentration of the lithium chloride solution is preferably 0.01-0.8 mol·L⁻¹. -1 For example, in some implementations, 0.01 mol·L⁻¹ is used. -1 0.05 mol·L -1 0.1 mol·L -1 0.2 mol·L -1 0.3 mol·L -1 0.4 mol·L -1 0.5 mol·L -1 0.6 mol·L -1 0.7 mol·L -1 0.8 mol·L -1 .

[0057] In step 2) of the present invention, the preferred process for saturating lithium ion adsorption of x-UA in lithium chloride solution is as follows: mix x-UA with lithium chloride solution, stir magnetically for 1-2 days, and then age for 2-10 hours.

[0058] In step 3) of this invention, the detergent contains 0.1-1 mol·L⁻¹ -1A mixture of ferric chloride hydrochloric acid solution, tributyl phosphate, and ethyl acetate in a mass ratio of 1:1 to 5:5, such as 1:1:5, 1:2:5, 1:3:5, 1:4:5, or 1:5:5 in some embodiments, wherein the tributyl phosphate and ethyl acetate are pure substances, and the pH of the hydrochloric acid solution is 1. Alternatively, the detergent contains 0.1-1 mol·L⁻¹ of... -1 A mixture of ferric chloride hydrochloric acid solution, a carboxylic acid ionic liquid, and ethyl acetate in a mass ratio of 1:0.1-0.5:5, such as 1:0.1:5, 1:0.2:5, 1:0.3:5, 1:0.4:5, or 1:0.5:5 in some embodiments. The carboxylic acid ionic liquid and ethyl acetate are pure substances, and the pH of the hydrochloric acid solution is 1. The carboxylic acid ionic liquid is an ionic compound composed of a hydroxyl-containing organic cation and a carboxylate anion, such as one or more of 1-hydroxyethyl-3-methylimidazolium acetate, 1-hydroxyethyl-3-methylimidazolium carboxylate, and hydroxyethyltrimethylammonium acetate.

[0059] In step 3) of the present invention, the preferred washing process is as follows: soaking Li-x-UA in detergent for 4-6 hours, and then rinsing with detergent for 0.5-1 hours.

[0060] In step 3) of the present invention, the preferred temperature for vacuum drying is 20-60°C.

[0061] The aluminum hydroxide-based adsorbent prepared by the method of this invention can be used in the selective adsorption of lithium ions, especially in the extraction of lithium ions from brine in salt lakes with a magnesium-to-lithium ratio >250. The lithium adsorption capacity at room temperature reaches as high as 23.18 mg / g. -1 .

[0062] In this invention, room temperature is defined as 10-30℃.

[0063] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to embodiments and comparative examples.

[0064] In the following examples and comparative examples, the various processes and methods not described in detail are conventional methods known in the art. Unless otherwise specified, the materials, reagents, apparatus, instruments, equipment, etc., used in the following examples and comparative examples are commercially available.

[0065] Example 1

[0066] like Figure 1 As shown, the preparation method of aluminum hydroxide-based adsorbent material is as follows:

[0067] 1) Add 100 mL of a 0.5 mol·L⁻¹ solution to the solution. -1Add 140 mL of a 0.5 mol·L⁻¹ aluminum salt solution (aluminum chloride) to the solution. -1 A urea solution was prepared, with the molar ratio of aluminum salt to urea controlled at 1:1.4. After thorough mixing at room temperature, the resulting mixture was transferred to a constant-temperature water bath at 90°C and stirred continuously with a magnetic stirrer for one day. Subsequently, it was allowed to cool naturally to room temperature and stand for 5 hours (ultra-homogeneous precipitation). The filter residue collected by vacuum filtration was then freeze-dried. The product was designated as 140-UA.

[0068] 2) Add 140-UA to a lithium chloride solution (concentration 0.1 mol·L⁻¹). -1 In this process, the mass ratio of 140-UA to lithium chloride was controlled at 1:2, and the mixture was magnetically stirred at room temperature for 1.5 days, followed by aging for 5 hours (Li... + (Saturated adsorption). The filter residue collected by vacuum filtration was then freeze-dried. The product was designated Li-140-UA.

[0069] 3) Contain 1 mol·L -1 A detergent (FeCl3-TBP-EtOAc) is obtained by mixing ferric chloride hydrochloric acid solution (pH=1), tributyl phosphate and ethyl acetate in a mass ratio of 1:2:5.

[0070] After soaking Li-140-UA in detergent for 5 hours, it was rinsed with detergent for 0.7 hours, vacuum filtered, and the resulting filter residue was vacuum dried at 40°C to obtain the adsorbent material, which was named Li-templated-140-UA.

[0071] Example 2

[0072] In Example 1, aluminum chloride was replaced with aluminum sulfate. All other procedures were the same as in Example 1.

[0073] Example 3

[0074] In Example 1, aluminum chloride was replaced with aluminum nitrate. All other procedures were the same as in Example 1.

[0075] Example 4

[0076] The ultra-uniform precipitation conditions in Example 1 were replaced with: water bath temperature controlled at 30°C, continuous stirring with a magnetic stirrer for 2 days, followed by natural cooling to room temperature and standing for 2 hours. Other operations were the same as in Example 1.

[0077] Example 5

[0078] The ultra-uniform precipitation conditions in Example 1 were replaced with: water bath temperature controlled at 50°C, continuous stirring with a magnetic stirrer for 1.5 days, followed by natural cooling to room temperature and standing for 10 hours. Other operations were the same as in Example 1.

[0079] Example 6

[0080] Li in Example 1 + The conditions for saturated adsorption were changed to: controlling the mass ratio of 140-UA and lithium chloride to 1:1, magnetically stirring at room temperature for 1 day, followed by aging for 10 hours. Other operations were the same as in Example 1.

[0081] Example 7

[0082] Li in Example 1 + The conditions for saturated adsorption were changed as follows: the mass ratio of 140-UA to lithium chloride was controlled at 1:3, magnetic stirring was performed at room temperature for 2 days, followed by aging for 2 hours. Other operations were the same as in Example 1.

[0083] Example 8

[0084] Replace the detergent in Example 1 with:

[0085] Containing 1 mol·L -1 A detergent is obtained by mixing a hydrochloric acid solution of ferric chloride (pH=1), a carboxyl ionic liquid, and ethyl acetate in a mass ratio of 1:0.3:5, wherein the carboxylic acid ionic liquid is 1-hydroxyethyl-3-methylimidazolium carboxylate.

[0086] After soaking Li-140-UA in detergent for 6 hours, it was rinsed with detergent for 0.5 hours, vacuum filtered, and the resulting filter residue was vacuum dried at 20°C to obtain the adsorbent material, which was named Li-templated-140-UA. Other operations were the same as in Example 1.

[0087] Example 9

[0088] Replace the detergent in Example 1 with:

[0089] Containing 1 mol·L -1 A detergent is obtained by mixing a hydrochloric acid solution of ferric chloride (pH=1), a carboxyl ionic liquid, and ethyl acetate in a mass ratio of 1:0.3:5. The carboxylic acid ionic liquid is 1-hydroxyethyl-3-methylimidazolium acetate.

[0090] After soaking Li-140-UA in detergent for 4 hours, it was rinsed with detergent for 1 hour, vacuum filtered, and the resulting filter residue was vacuum dried at 60°C to obtain the adsorbent material, which was named Li-templated-140-UA. Other operations were the same as in Example 1.

[0091] Example 10

[0092] Replace the detergent in Example 1 with:

[0093] Containing 1 mol·L -1 A detergent is obtained by mixing a hydrochloric acid solution of ferric chloride (pH=1), a carboxyl ionic liquid, and ethyl acetate in a mass ratio of 1:0.3:5. The carboxyl ionic liquid is hydroxyethyltrimethylammonium acetate.

[0094] After soaking Li-140-UA in detergent for 5 hours, it was rinsed with detergent for 0.8 hours, vacuum filtered, and the resulting filter residue was vacuum dried at 40°C to obtain the adsorbent material, which was named Li-templated-140-UA. Other operations were the same as in Example 1.

[0095] Comparative Example 1

[0096] like Figure 1 As shown, the detergent in step 3) of Example 1 was replaced with deionized water, and the other operations were the same as in Example 1. The resulting adsorbent material was named Li-W-140-UA.

[0097] Comparative Example 2

[0098] like Figure 1 As shown, the detergent in step 3) of Example 1 was replaced with a 35% HCl solution, and other operations were the same as in Example 1. The resulting adsorbent material was named Li-H-140-UA.

[0099] Comparative Example 3

[0100] like Figure 1 As shown, the detergent in step 3) of Example 1 was replaced with a solution containing 1 mol·L⁻¹ -1 The ferric chloride hydrochloric acid solution (pH=1) was used, and other operations were the same as in Example 1. The resulting adsorbent was named Li-F-140-UA.

[0101] Comparative Example 4

[0102] like Figure 1 As shown, the detergent in step 3) of Example 1 was replaced with ethyl acetate, and the other operations were the same as in Example 1. The resulting adsorbent material was named Li-E-140-UA.

[0103] After washing the Li-140-UA prepared in step 2) with different detergents from Examples 1-10 and Comparative Examples 1-4, the Li + elution rate and Al 3+ The elution rates are shown in Table 1.

[0104] Table 1. Effects of different detergents on Li in Li-140-UA + And Al 3+ elution rate

[0105]

[0106] As can be seen from Table 1, the detergents used in Examples 1-10 were applied to Li + It has the highest elution rate.

[0107] The Li-templated-140-UA prepared in Examples 1-10 was applied to different concentrations of Li + Adsorption of lithium in a solution (lithium chloride solution, a single metal cation solution).

[0108] Tests were conducted on the adsorption of different concentrations of Li by Li-templated-140-UA at different temperatures. + The equilibrium adsorption capacity of the solution was determined, and isotherms were plotted and fitted using the Langmuir, Freundlich, Emkin, and Dubinin-Radushkevich equations, respectively. The results are as follows: Figure 2 As shown in (a)-(d) and Table 2-3.

[0109] Table 2. Li adsorbed by Li-templated-140-UA at different temperatures + The parameters obtained by fitting the isotherms to the Langmuir and Freundlich equations respectively

[0110]

[0111] In Table 2, q m For the maximum adsorption capacity, K L K is the Langmuir adsorption constant. F R is the Freundlich adsorption constant, n is the Freundlich adsorption index, and R is the Freundlich adsorption constant. 2 The correlation coefficients are independent of each other.

[0112] Table 3. Li adsorbed by Li-templated-140-UA at different temperatures + The parameters of the isotherms were obtained by fitting the Temkin and Dubinin-Radushkevich equations, respectively.

[0113]

[0114] In Table 3, b T Let A be the Temkin adsorption constant. T K is the Temkin equilibrium constant. ad The adsorption constant is used to characterize the adsorption free energy, where E is the adsorption free energy and R is the adsorption free energy. 2 The correlation coefficients are independent of each other.

[0115] The adsorption of Li by Li in Li-templated-140-UA prepared in Examples 1-10 at different temperatures and at different times was investigated. + The kinetic curves obtained from the saturated adsorption capacity were fitted with pseudo-first-order and pseudo-second-order kinetic equations, respectively, and the results are as follows: Figure 3 As shown in (a)-(b) and Table 4.

[0116] Table 4. Li adsorbed by Li-templated-140-UA at different temperatures + The parameters obtained by fitting the kinetic curves with pseudo-first-order and pseudo-second-order kinetic equations are respectively

[0117]

[0118] In Table 4, k1 and k2 are the first-order and second-order adsorption kinetic constants, respectively, and q e The values ​​of R1 and R2 are independent equilibrium adsorption amounts, and the values ​​of R2 are independent correlation coefficients.

[0119] The adsorption thermodynamic functions of Li-templated-140-UA prepared in Examples 1-10 at different temperatures are as follows: Figure 4 In section (a), the parameters are shown in Table 5. The pseudo-first-order adsorption kinetic rate constants at different temperatures are fitted using the Arrhenius empirical formula as follows: Figure 4 As shown in (b).

[0120] Table 5. Adsorption thermodynamic parameters of Li-templated-140-UA at different temperatures

[0121]

[0122] In Table 5, q m For the maximum adsorption capacity, K L K is the Langmuir adsorption constant. D (L) is the theoretical adsorption equilibrium constant, Δ ads G ° For the standard adsorption Gibbs free energy change, Δ ads H ° For standard adsorption enthalpy change, Δ ads S °R² is the standard adsorption entropy change, and R² is the correlation coefficient.

[0123] The 140-UA prepared in Examples 1-10, the Li-W-140-UA prepared in Comparative Example 1, and the Li-templated-140-UA prepared in Examples 1-10 were respectively applied to Li + The adsorption of lithium in simulated salt lake brine with multiple metal cations coexisting at equal concentrations and the adsorption of lithium in simulated Qarhan Salt Lake brine are shown in Table 6. The concentrations of various ions in Qarhan Salt Lake brine and simulated Qarhan Salt Lake brine are shown in Tables 7-8.

[0124] Table 6. Concentrations of various ions in the brine of Qarhan Salt Lake and the simulated brine of Qarhan Salt Lake

[0125]

[0126] Table 7 shows the separation factors and partition coefficients of various metal cations when 140-UA, Li-W-140-UA, and Li-templated-140-UA were applied to the adsorption of lithium in simulated salt lake brine with multiple metal cations coexisting. The initial concentrations of all metal cations were maintained at 10 mmol·L⁻¹. -1

[0127]

[0128] In Table 7, and These are the separation factor and partition coefficient for various metal cations, respectively.

[0129] Table 8. Separation factors and partition coefficients of various metal cations when Li-templated-140-UA is applied to the adsorption of lithium in simulated Chaka Salt Lake brine.

[0130]

[0131] In Table 8, This is the initial concentration. The concentration at adsorption equilibrium. To balance the adsorption amount, and These are the separation factor and partition coefficient for various metal cations, respectively.

[0132] Obviously, the above embodiments are merely examples for clear illustration and are not intended to limit the embodiments. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all embodiments here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing aluminum hydroxide-based adsorbent materials, characterized in that, Includes the following steps: 1) Mix aluminum salt solution and urea solution evenly at room temperature, stir magnetically at 30℃-90℃, cool, let stand, vacuum filter, freeze dry the filter residue to obtain x-UA; 2) At room temperature, x-UA was subjected to lithium-ion saturation adsorption in a lithium chloride solution. After vacuum filtration, the filter residue was freeze-dried to obtain Li-x-UA. 3) Li-x-UA was washed with detergent, and after washing, it was vacuum filtered and the filter residue was vacuum dried to obtain aluminum hydroxide-based adsorbent material; The detergent contains 0.1-1 mol·L⁻¹ -1 A mixture of ferric chloride hydrochloric acid solution, carboxylic acid ionic liquid, and ethyl acetate in a mass ratio of 1:0.1-0.5:5; wherein the carboxylic acid ionic liquid is one or more of 1-hydroxyethyl-3-methylimidazolium acetate, 1-hydroxyethyl-3-methylimidazolium carboxylate, and hydroxyethyltrimethylammonium acetate. The molar ratio of the aluminum salt to urea is 1:1.4; In step 3), the washing process is as follows: soak Li-x-UA in detergent for 4-6 hours, and then rinse with detergent for 0.5-1 hour.

2. The method for preparing the aluminum hydroxide-based adsorbent material according to claim 1, characterized in that, In step 1), one or more of the following characteristics are present: The aluminum salt is one or more of aluminum chloride, aluminum sulfate, and aluminum nitrate; The concentration of the aluminum salt solution is 0.1-1 mol·L⁻¹ -1 ; The concentration of the urea solution is 0.1-1 mol·L⁻¹ -1 .

3. The method for preparing the aluminum hydroxide-based adsorbent material according to claim 1, characterized in that, In step 1), stir magnetically at 30℃-90℃ for 1-2 days, cool to room temperature, and let stand for 2-10 hours.

4. The method for preparing the aluminum hydroxide-based adsorbent material according to claim 1, characterized in that, In step 2), one or more of the following characteristics are present: The mass ratio of x-UA to lithium chloride is 1:1 to 1:3; The concentration of the lithium chloride solution is 0.01-0.8 mol·L⁻¹. -1 .

5. The method for preparing the aluminum hydroxide-based adsorbent material according to claim 1, characterized in that, In step 2), the process of saturating x-UA with lithium ions in lithium chloride solution is as follows: mix x-UA with lithium chloride solution, stir magnetically for 1-2 days, and then age for 2-10 hours.

6. The method for preparing the aluminum hydroxide-based adsorbent material according to claim 1, characterized in that, In step 3), one or more of the following characteristics are present: The temperature for vacuum drying is 20-60℃; The pH of the hydrochloric acid solution is 1.

7. The aluminum hydroxide-based adsorbent prepared by the method for preparing aluminum hydroxide-based adsorbents according to any one of claims 1-6.

8. The application of the aluminum hydroxide-based adsorbent material according to claim 7 in the selective adsorption of lithium ions.

9. The application of the aluminum hydroxide-based adsorbent material according to claim 8 in the selective adsorption of lithium ions, characterized in that, Application of the aluminum hydroxide-based adsorbent material in extracting lithium ions from salt lake brine with a magnesium-to-lithium ratio >250.

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