Aluminum-based lithium adsorbent and preparation method thereof

Abstract

This disclosure discloses an aluminum-based lithium adsorbent and a method for preparing the same. The method comprises the following steps: mixing aluminum chloride and sodium hydroxide solution, followed by heating and reacting to obtain a precursor; mixing the obtained precursor with lithium chloride, adding MoS2, and ball milling to obtain the aluminum-based lithium adsorbent. The MoS2 is synthesized by a hydrothermal method and has a nanoflower-like flaky structure.

Description

Technical Field

[0001] The present disclosure belongs to the technical field of adsorbents, and particularly relates to an aluminum-based lithium adsorbent and a preparation method thereof. Background Art

[0002] Lithium, the lightest naturally occurring metallic element with the lowest standard electrode potential and the largest electrochemical equivalent, is globally recognized as the "white oil of the future." As China's largest power battery producer and the largest consumer of lithium resources, improving lithium mining efficiency is a crucial issue.

[0003] One of the main sources of lithium resources is lithium ore, but after hundreds of years of mining, large-scale, high-grade, and easily mined high-quality lithium resource projects are now scarce, resulting in high production costs for lithium extraction from ore. According to USGS statistics, the total global lithium resources in 2021 were 85.56 million tons of metal, of which 65% of lithium resources existed in brine, including salt lake brine (59%), geothermal brine (3%), and oilfield brine (3%). Currently, the raw material for lithium extraction from brine is mainly salt lake brine. In recent years, the upgrading and iteration speed of salt lake lithium extraction technology is accelerating. At present, aluminum salt adsorbents have been successfully applied to industrial production. The United States' FMC Corporation and my country's Qinghai Lanke Lithium Industry both use aluminum salt adsorbents to recover lithium from the Hombre Muerto Salt Lake and the Qarhan Salt Lake, respectively.

[0004] The use of aluminum salt adsorbents for lithium extraction from salt lakes is developed from the aluminum salt precipitation method for lithium extraction. The expression of the adsorbent is LiX·2Al(OH)3·nH2O, where X represents an anion, usually Cl; n represents the number of crystal water. It is a compound generated by the insertion of LiCl into Al(OH)3. When the defects of Al(OH)3 obtained by chemical or mechanochemical methods appear in the form of a matrix, the intercalation process of LiCl will be enhanced. The Al-OH layer is not harmonious, and the Al-OH layer in the area in contact with LiCl will be disorganized. In this case, the obtained compound has a defective structure of the initial compound. Under this structure, the ionic radius is similar to that of Li + Close Mg 2+ , will eliminate Mg 2+ The possibility of inclusion into defective structures. The Li / Al molar ratio is 0.38±0.01. When the molar fraction is too high, it will affect the mechanical strength of the microcrystals and make the Al(OH)3 crystal structure fragile. The layered structure of traditional aluminum-based adsorbents has low mechanical strength, resulting in low lithium storage during the adsorption process. As the adsorption process prolongs, the intercalation structure becomes unstable and the van der Waals forces are destroyed, which in turn increases dissolution and deteriorates the desorption effect. Summary of the Invention

[0005] The present disclosure aims to address at least one of the technical problems existing in the aforementioned prior art. To this end, the present disclosure provides an aluminum-based lithium adsorbent and a method for its preparation. This method achieves a high lithium recovery rate and has great potential for application.

[0006] According to the first aspect of the present disclosure, a method for preparing the aluminum-based lithium adsorbent is proposed, comprising the following steps:

[0007] S1: mixing aluminum chloride and sodium hydroxide solution and heating them to react to obtain a precursor;

[0008] S2: The precursor is mixed with lithium chloride, MoS2 is added, and an aluminum-based lithium adsorbent is obtained after ball milling; the MoS2 is prepared by dissolving sodium molybdate in an ethanol aqueous solution, adding hydroxylamine hydrochloride and thiourea in sequence, and then heating and reacting. The MoS2 is in the form of nano-flower cluster sheets.

[0009] In some embodiments, in step S1, the concentration of the sodium hydroxide solution ranges from 0.01 mol / L to 5 mol / L.

[0010] In some embodiments, in step S1, the concentration of the sodium hydroxide solution ranges from 0.05 mol / L to 2 mol / L.

[0011] In some embodiments, in step S1, the liquid-to-solid ratio of the sodium hydroxide solution to aluminum chloride is in the range of (2 mL to 40 mL): 1 g.

[0012] In some embodiments, in step S1, the liquid-to-solid ratio of the sodium hydroxide solution to aluminum chloride is in the range of (3 mL to 5 mL): 1 g.

[0013] In some embodiments, in step S1, the temperature of the heating reaction is 40°C to 90°C, and the reaction time is 5 min to 90 min.

[0014] In some embodiments, in step S1, the temperature of the heating reaction is 50°C to 80°C, and the reaction time is 10 min to 40 min.

[0015] In some embodiments, in step S1, the particle size of the precursor is 30 μm to 280 μm.

[0016] In some embodiments, in step S2, the precursor obtained in step S1 is further subjected to solid-liquid separation, washing, and drying before being mixed with lithium chloride.

[0017] In some embodiments, in step S2, the particle size of the MoS2 is 5 μm to 10 μm.

[0018] In some embodiments, in step S2, the ethanol aqueous solution is prepared by mixing ethanol and water in a volume ratio of 1:1.

[0019] In some embodiments, in step S2, the molar ratio of the lithium chloride to the Li / Al precursor is in the range of 0.02 to 0.2.

[0020] In some embodiments, in step S2, the molar ratio of the lithium chloride to the Li / Al precursor is in the range of 0.08 to 0.1.

[0021] In some embodiments, in step S2, the amount of MoS2 added is 5 wt% to 15 wt% of the total mass of the mixture obtained by mixing the lithium chloride and the precursor.

[0022] In some embodiments, in step S2, the ball milling is dry ball milling, and stearic acid is used as a ball milling aid.

[0023] In some embodiments, in step S2, the ball milling speed is 200 r / min to 11500 r / min, and the time is 1 h to 8 h.

[0024] In some embodiments, in step S2, the ball milling speed is 300 r / min to 500 r / min, and the time is 2 h to 7 h.

[0025] According to a second aspect of the present disclosure, an aluminum-based lithium adsorbent is provided, wherein the aluminum-based lithium adsorbent is in the form of nano-flower cluster sheets.

[0026] In some embodiments, the aluminum-based lithium adsorbent has a particle size of 10 μm to 210 μm, and a lithium adsorption capacity greater than 5 mg / g.

[0027] According to the third aspect of the present disclosure, the application of the aluminum-based lithium adsorbent proposed in the second aspect of the present disclosure in lithium extraction from salt lakes is proposed.

[0028] According to one embodiment of the present disclosure, there are at least the following beneficial effects:

[0029] (1) The aluminum-based lithium adsorbent prepared in the present invention contains nano-flower cluster flake MoS2, which is synthesized by a hydrothermal method and presents a layered structure. Strong covalent bonds act within the S-Mo-S hexagonal structural layers, and weak van der Waals forces act between the layers. The layered nano-flower sheet structure allows the embedding and de-embedding of lithium ions and has a good lithium storage mechanism.

[0030] (2) The preparation method disclosed in the present invention is based on the mechanochemical effect of lithium chloride inserted into the aluminum hydroxide layer. The precursor is first synthesized by hydrothermal synthesis; then lithium chloride and nano-flower cluster flake MoS2 are doped into the defect structure of the precursor by mechanical ball milling to generate a material capable of separating Mg 2+ He Li + , Opposition + A specially selective molybdenum sulfide / lithium chloride / aluminum hydroxide composite adsorbent. The aluminum-based lithium adsorbent prepared by the above method has a good lithium storage mechanism, a layered structure with high mechanical strength, a stable intercalation structure, a particle size between 10μm and 210μm, and a working adsorption capacity greater than 5mg / g, effectively improving the adsorption capacity of aluminum-based adsorbents. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The present disclosure is further described below with reference to the accompanying drawings and embodiments, wherein:

[0032] Figure 1 Schematic diagram of the process disclosed herein;

[0033] Figure 2 This is a SEM image of the aluminum-based lithium adsorbent synthesized in Example 1 of the present disclosure, magnified 10,000 times;

[0034] Figure 3 This is a 30,000-fold magnified SEM image of the aluminum-based lithium adsorbent synthesized in Example 1 of the present disclosure. DETAILED DESCRIPTION

[0035] The following will clearly and completely describe the concept and technical effects of the present disclosure in conjunction with embodiments to fully understand the purpose, features and effects of the present disclosure.

[0036] The preparation method of nano-flower cluster flake MoS2 is as follows:

[0037] 8 mmol of sodium molybdate was dissolved in 120 mL of a 1:1 ethanol-water mixture, and 16 mmol of hydroxylamine hydrochloride was added and stirred thoroughly. Then, 16 mmol of thiourea was added, stirred thoroughly, and transferred to a 200 mL reactor. The reaction was set at 190°C for 24 hours. After cooling, the mixture was filtered under reduced pressure and washed three times with deionized water and ethanol. The resulting product was vacuum-dried at 50°C for 6 hours and then calcined at 500°C under nitrogen for 5 hours to obtain MoS2 with a unique flower-like structure.

[0038] Example 1

[0039] A method for preparing an aluminum-based lithium adsorbent, such as Figure 1 As shown, the following steps are included:

[0040] S1: Weigh 10 g of aluminum chloride powder and 100 mL of 1 mol / L sodium hydroxide solution, mix them evenly at a liquid-to-solid ratio of 10:1, place them in a beaker in a constant temperature water bath, set the constant temperature water bath to 50°C, and react for 20 minutes;

[0041] S2: After the hydrothermal reaction reaches the end point, the beaker is removed and the mixed slurry is poured out, vacuum filtered, washed, and dried in a drying oven at 40°C for 2 hours to obtain a NaCl·2Al(OH)3·3H2O precursor;

[0042] S3: Lithium chloride and the NaCl·2Al(OH)3·3H2O precursor obtained in step S2 were weighed according to a Li / Al molar ratio of 0.08, and 5 wt% of nano-flower cluster flake MoS2 was added. 5 mm stainless steel balls were selected as grinding balls, the ball milling speed was controlled to 300 r / min, and the ball milling time was set to 4 h to obtain an aluminum-based lithium adsorbent.

[0043] The results show that the particle size of the obtained adsorbent is between 30 and 180 μm.

[0044] The SEM image of the aluminum-based lithium adsorbent prepared in Example 1 is as follows: Figure 2 、 Figure 3 As shown, the aluminum-based lithium adsorbent contains flower-shaped MoS2. The MoS2 nanoflowers are composed of dozens to hundreds of petal tissues, which grow radially from a center in all directions. The average particle size of each nanoflower is 5 to 10 μm.

[0045] Example 2

[0046] A method for preparing an aluminum-based lithium adsorbent comprises the following steps:

[0047] S1: Weigh 20 g of aluminum chloride powder and 160 mL of 2 mol / L sodium hydroxide solution, mix them evenly at a liquid-to-solid ratio of 8:1, place them in a beaker in a constant temperature water bath, set the constant temperature water bath temperature to 60°C, and react for 30 min;

[0048] S2: After the hydrothermal reaction reaches the end point, the beaker is removed and the mixed slurry is poured out, vacuum filtered, washed, and dried in a drying oven at 40°C for 2 hours to obtain a NaCl·2Al(OH)3·3H2O precursor;

[0049] S3: Lithium chloride and the NaCl·2Al(OH)3·3H2O precursor obtained in step S2 were weighed according to a Li / Al molar ratio of 0.1, and 10 wt% of nano-flower cluster flake MoS2 was added. 5 mm stainless steel balls were selected as grinding balls, the ball milling speed was controlled to 400 r / min, and the ball milling time was set to 6 h to obtain an aluminum-based lithium adsorbent.

[0050] The results show that the particle size of the obtained adsorbent is between 10 and 150 μm.

[0051] Example 3

[0052] A method for preparing an aluminum-based lithium adsorbent comprises the following steps:

[0053] S1: Weigh 30 g of aluminum chloride powder and 600 mL of 1 mol / L sodium hydroxide solution, mix them evenly at a liquid-to-solid ratio of 20:1, place them in a beaker in a constant temperature water bath, set the constant temperature water bath temperature to 70°C, and react for 40 min;

[0054] S2: After the hydrothermal reaction reaches the end point, the mixed slurry is poured out and vacuum filtered. After washing, the leached residue is dried in a drying oven at 40°C for 2 hours to obtain a NaCl·2Al(OH)3·3H2O precursor;

[0055] S3: Lithium chloride and the NaCl·2Al(OH)3·3H2O precursor obtained in step S2 were weighed according to a Li / Al molar ratio of 0.09, and 15 wt% of nano-flower cluster flake MoS2 was added. 5 mm stainless steel balls were selected as grinding balls, the ball milling speed was controlled to 500 r / min, and the ball milling time was set to 6 h to obtain an aluminum-based lithium adsorbent.

[0056] The results show that the particle size of the obtained adsorbent is between 10 and 150 μm.

[0057] Example 4

[0058] A method for preparing an aluminum-based lithium adsorbent comprises the following steps:

[0059] S1: Weigh 40 g of aluminum chloride powder and 160 mL of 1.5 mol / L sodium hydroxide solution, mix them evenly at a liquid-to-solid ratio of 4:1, place them in a beaker in a thermostatic water bath, set the thermostatic water bath to 60°C, and react for 35 minutes;

[0060] S2: After the hydrothermal reaction reaches the end point, the mixed slurry is poured out and vacuum filtered. After washing, the leached residue is dried in a drying oven at 40°C for 2 hours to obtain a NaCl·2Al(OH)3·3H2O precursor;

[0061] S3: Lithium chloride and the NaCl·2Al(OH)3·3H2O precursor obtained in step S2 were weighed according to a Li / Al molar ratio of 0.1, and 10 wt% of nano-flower cluster flake MoS2 was added. 5 mm stainless steel balls were selected as grinding balls, the ball milling speed was controlled to 400 r / min, and the ball milling time was set to 6 h to obtain an aluminum-based lithium adsorbent.

[0062] The results show that the particle size of the obtained adsorbent is between 10 and 150 μm.

[0063] Comparative Example 1

[0064] An aluminum-based lithium adsorbent is prepared by mechanical ball milling, comprising the following steps:

[0065] Weigh 10g of aluminum chloride, sodium hydroxide, and lithium chloride (with a Li / Al molar ratio of 0.08) and mix them. Place the mixture in a ball mill using 5mm stainless steel balls. Control the mill speed at 300 rpm and set the dry milling time to 4 hours. Add 10ml of deionized water and wet mill for 2 hours. Maintain the same ball-to-material mass ratio and speed settings during both dry and wet milling to obtain an intercalated LiCl·2Al(OH)3·3H2O adsorbent.

[0066] Comparative Example 2

[0067] An aluminum-based lithium adsorbent, which differs from Example 1 only in that nano-flower cluster flake MoS2 is not added in step S3, comprises the following steps:

[0068] S1: Weigh 10 g of aluminum chloride powder and 100 mL of 1 mol / L sodium hydroxide solution, mix them evenly at a liquid-to-solid ratio of 10:1, place them in a beaker in a constant temperature water bath, set the constant temperature water bath to 50°C, and react for 20 minutes;

[0069] S2: After the hydrothermal reaction reaches the end point, the beaker is removed and the mixed slurry is poured out, vacuum filtered, washed, and dried in a drying oven at 40°C for 2 hours to obtain a NaCl·2Al(OH)3·3H2O precursor;

[0070] S3: Lithium chloride and the NaCl·2Al(OH)3·3H2O precursor obtained in step S2 were weighed according to a Li / Al molar ratio of 0.08, 5 mm stainless steel balls were selected as grinding balls, the ball milling speed was controlled to 300 r / min, and the ball milling time was set to 4 h to obtain an aluminum-based lithium adsorbent.

[0071] Test example

[0072] The aluminum-based lithium adsorbent prepared in Example 1 was applied to Li + Lithium was extracted from aluminum salt solution with a high magnesium-lithium ratio of 598 mg / L. The cyclic adsorption and desorption experiments were carried out on Li + The adsorption capacity is 5.12-8.37 mg / g, which can achieve a magnesium-lithium separation efficiency greater than 99.9%, effectively improving the adsorption capacity of aluminum-based adsorbents.

[0073] The composition of the high magnesium-to-lithium ratio aluminum salt solution is shown in Table 1:

[0074] Table 1 Brine composition analysis table (pH = 7.07)

[0075]

[0076] The adsorption effect of the adsorbent prepared in Example 1 is shown in Table 2 and Table 3:

[0077] Table 2 Before and after adsorption

[0078]

[0079] Table 3 Adsorbent performance indicators

[0080]

[0081] The aluminum-based lithium adsorbent prepared in Example 2 was applied to Li + Lithium was extracted from brine with a concentration of 0.6 g / L. The cyclic adsorption and analysis experiments showed that Li + The adsorption capacity is 8.25 mg / g, which can achieve a magnesium-lithium separation efficiency greater than 99.9%, effectively improving the adsorption capacity of aluminum-based adsorbents.

[0082] The aluminum-based lithium adsorbent prepared in Example 3 was applied to Li + Lithium extraction from brine with a high magnesium-lithium ratio of 2.6 g / L, and cyclic adsorption and analysis experiments on Li + The adsorption capacity is 10.61 mg / g, which can achieve a magnesium-lithium separation efficiency greater than 99.9%, effectively improving the adsorption capacity of aluminum-based adsorbents.

[0083] The aluminum-based lithium adsorbent prepared in Example 4 was applied to Li + Lithium was extracted from brine with a concentration of 0.6 g / L. The cyclic adsorption and analysis experiments showed that Li + The adsorption capacity is 10.15 mg / g, which can achieve a magnesium-lithium separation efficiency greater than 99.9%, effectively improving the adsorption capacity of aluminum-based adsorbents.

[0084] The adsorbent prepared in Comparative Example 1 was used to perform an adsorption experiment on the brine in Table 1. The results are shown in Tables 4 and 5:

[0085] Table 4 Comparative Example 1 before and after adsorption

[0086]

[0087] Table 5 Performance index of adsorbent of comparative example 1

[0088]

[0089] The adsorbent prepared in Comparative Example 2 was used to perform an adsorption test on the brine in Table 1. The results are shown in Tables 6 and 7:

[0090] Table 6 Comparative Example 2 before and after adsorption

[0091]

[0092] Table 7 Comparative Example 2 Adsorbent Performance Index

[0093]

[0094] As can be seen from Comparative Examples 1 and 2, the adsorbents prepared by the mechanical ball milling method and the undoped MoS2 method have a mass adsorption capacity of 2.56 mg / g and 4.99 mg / g for Li, respectively, an adsorption rate of 51.17% and 99.42%, and a resolution rate of 36.58% and 39.66%, respectively. Compared with the composite adsorbent prepared by the hydrothermal synthesis method of doped MoS2 in Example 1, the adsorption capacity of Li is 8.37 mg / g, the adsorption rate is 99.98%, and the resolution rate is 99.95%. It can be seen that the adsorbent prepared by the traditional mechanical ball milling method has a low adsorption capacity and poor resolution effect; although the aluminum-based lithium adsorbent prepared by the undoped MoS2 method has an improved adsorption capacity, the resolution effect is still very poor. The aluminum-based lithium adsorbent prepared by the preparation method proposed in the present disclosure has a high adsorption capacity, good resolution effect, and good magnesium-lithium separation effect.

Claims

1. A method for preparing an aluminum-based lithium adsorbent, characterized in that: The following steps are involved: S1: mixing aluminum chloride and sodium hydroxide solution and heating them to react to obtain a precursor; S2: The precursor is mixed with lithium chloride, MoS2 is added, and the mixture is ball-milled to obtain an aluminum-based lithium adsorbent; the MoS2 is prepared by dissolving sodium molybdate in an ethanol aqueous solution, adding hydroxylamine hydrochloride and thiourea in sequence, and then heating to react. The MoS2 is in the form of nano-flower cluster flakes; In step S2, the precursor is subjected to solid-liquid separation, washing and drying before being mixed with lithium chloride; In step S2, the Li / Al molar ratio of the lithium chloride to the precursor is 0.02 to 0.2; In step S2, the amount of MoS2 added is 5wt% to 15wt% of the total mass of the mixture obtained by mixing the lithium chloride and the precursor.

2. The method for preparing the aluminum-based lithium adsorbent according to claim 1, wherein: In step S1, the concentration range of the sodium hydroxide solution is 0.01 mol / L to 5 mol / L.

3. The method for preparing the aluminum-based lithium adsorbent according to claim 1, characterized in that: In step S1, the liquid-to-solid ratio of the sodium hydroxide solution to the aluminum chloride is in the range of (2 mL to 40 mL): 1 g.

4. The method for preparing the aluminum-based lithium adsorbent according to claim 1, wherein: In step S1, the temperature of the heating reaction is 40° C. to 90° C., and the reaction time is 5 min to 90 min.

5. The method for preparing the aluminum-based lithium adsorbent according to claim 1, wherein: In step S1, the particle size of the precursor is 30 μm to 280 μm.

6. The method for preparing the aluminum-based lithium adsorbent according to claim 1, characterized in that: In step S2, the particle size of the MoS2 is 5 μm to 10 μm.

7. The method for preparing the aluminum-based lithium adsorbent according to claim 1, characterized in that: In step S2, the ethanol aqueous solution is prepared by mixing ethanol and water in a volume ratio of 1:

1.

8. The method for preparing the aluminum-based lithium adsorbent according to claim 1, characterized in that: In step S2, the ball milling is dry ball milling, and stearic acid is used as a ball milling aid.

9. The method for preparing an aluminum-based lithium adsorbent according to claim 1, wherein: In step S2, the ball milling speed is 200 r / min to 11500 r / min, and the time is 1 h to 8 h.

10. An aluminum-based lithium adsorbent, characterized in that Prepared by the preparation method according to any one of claims 1 to 9, the aluminum-based lithium adsorbent is in the form of nano-flower cluster sheets.

11. The aluminum-based lithium adsorbent according to claim 10, characterized in that The particle size of the aluminum-based lithium adsorbent is 10 μm to 210 μm, and the lithium adsorption capacity is greater than 5 mg / g.

12. Use of the aluminum-based lithium adsorbent according to claim 10 in extracting lithium from salt lakes.

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