Aluminum-based lithium adsorbent, its preparation method and application

Abstract

The application discloses an aluminum-based lithium adsorbent and a preparation method and application thereof, and belongs to the field of adsorbents. The aluminum-based lithium adsorbent is derived from a metal organic framework (MOFs) material as a precursor, has a highly porous structure, high adsorption capacity and high stability, and is helpful to realize efficient lithium extraction from salt lake brine. In the preparation method, the aluminum-based lithium adsorbent is prepared by in-situ conversion of the metal organic framework precursor. According to the selection of different lithium compound alkaline solutions, the aluminum-based adsorbent can be prepared, and the regulation of interlayer ions of the aluminum-based adsorbent can also be realized. In the adsorption process, the adsorption method is used to extract lithium from the salt lake brine. In the desorption process, deionized water is commonly used as a desorption liquid. In the adsorption process, the adsorption capacity can reach 6.8 mg / g, the solution loss rate is low, and the cycle and selection functions are provided.

Description

Technical Field

[0001] This invention relates to an aluminum-based lithium adsorbent, its preparation method, and its application, belonging to the field of adsorbents. Background Technology

[0002] Lithium, the lightest metallic element in nature with the lowest standard electrode potential, is globally recognized as the "white oil of the future." Global lithium resources mainly originate from lithium ores, salt lakes, and lepidolite. In China, the vast majority of lithium resources are stored in salt lake brines, mostly with a high magnesium-to-lithium ratio. Therefore, developing efficient lithium adsorbents for lithium extraction from salt lake brines is a crucial research topic. Currently, the main lithium adsorbents under research include aluminum-based adsorbents, manganese-based ion sieves, and titanium-based ion sieves. Although aluminum-based adsorbents have a relatively low lithium adsorption capacity, they possess unique advantages such as high selectivity, fast adsorption-desorption rates, simple regeneration processes, low cost, and ease of preparation. They are currently the only adsorbents with industrialized applications for lithium extraction from brine using adsorption methods.

[0003] Aluminum-based lithium adsorbent has a layered hydrotalcite structure, with the formula LiX·2Al(OH)3·n H2O, where X represents an anion, which can be Cl-. - CO3 2- OH - ; n represents the number of water molecules containing crystals. Commonly used preparation methods for aluminum-based lithium adsorbents include hydrothermal methods, precipitation methods, and ball milling methods. Researchers are dedicated to improving the adsorption capacity of aluminum-based adsorbents by increasing porosity and enhancing processability through granulation and doping. Recently, metal-organic frameworks (MOFs) have become an attractive porous material due to their large surface area, tunable functionality, unique porous structure, and moderate chemical stability. Furthermore, MOFs can also serve as precursors to prepare hydrotalcite structures with abundant reactivity, tunable composition, high porosity, and large surface area. Therefore, aluminum-based lithium adsorbents derived from MOFs possess highly porous structures, high adsorption capacity, and high stability, which is beneficial for achieving efficient lithium extraction from salt lake brine. Summary of the Invention

[0004] In view of this, existing work on the preparation of aluminum-based adsorbents focuses on improving the adsorption capacity of aluminum-based adsorbents by increasing porosity and improving processability through granulation and doping. This invention provides an aluminum-based lithium adsorbent, its preparation method and application. Using metal-organic framework (MOF) materials as precursors, an aluminum-based lithium adsorbent with a highly porous structure, high adsorption capacity and high stability is prepared, which helps to achieve efficient lithium extraction from salt lake brine.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for preparing an aluminum-based lithium adsorbent includes the following steps:

[0007] S1. Dissolve aluminum nitrate and 2-aminoterephthalic acid in ultrapure water and N,N-dimethylformamide, respectively;

[0008] S2. Thoroughly mix the two solutions in S1, then add the mixture to the reaction vessel and heat to react;

[0009] S3. Centrifuge the product obtained in S2, wash it with ethanol, and then dry it under vacuum.

[0010] S4. Disperse the product obtained in S3 in ultrapure water, add an alkaline solution of lithium compound while stirring, and continue heating and stirring until the reaction is complete.

[0011] S5. Stop stirring and allow the mixture to age to obtain a precipitate. Centrifuge the precipitate, wash it with ultrapure water, and then heat and dry it.

[0012] S6. The product obtained in S5 is desorbed with deionized water, centrifuged, and dried to obtain aluminum-based lithium adsorbent.

[0013] Based on the above technical solution, the present invention has the following further limitations:

[0014] Furthermore, the molar ratio of aluminum nitrate to p-2-aminoterephthalic acid in S1 is 2:1 to 1:2.

[0015] Furthermore, the reaction temperature in S2 is 120–140°C, and the reaction time is 20–24 hours;

[0016] In S3, the centrifugation speed is 8000-10000 rpm, the product is washed three times with ethanol, and the vacuum drying temperature is 100-150℃ for 8-12 hours.

[0017] The heating temperature in S4 is 75–95°C, and the reaction time is 8–16 hours.

[0018] The aging time in S5 is 12-24 hours; the centrifugation speed is 8000-10000 rpm; the drying temperature is 60-90℃; and the drying time is 12-24 hours.

[0019] In S6, the desorption temperature is 30℃~60℃, the desorption time is 3~9 hours, the centrifugation speed is 8000~10000 rpm, and the drying temperature is 60~90℃.

[0020] Furthermore, the amount of product obtained in S3 in S4 is 0.5–1.0 g, and the lithium compound content in the alkaline solution of the lithium compound is 5–15 mmol.

[0021] Furthermore, the alkaline solution of the lithium compound is any one of lithium hydroxide solution, sodium hydroxide solution of lithium chloride, or urea solution of lithium chloride.

[0022] Furthermore, in S5, the washing process involves three centrifugal washes with ultrapure water.

[0023] The present invention also provides an aluminum-based lithium adsorbent prepared by the above method.

[0024] This invention also provides the application of the above-mentioned aluminum-based lithium adsorbent in lithium extraction from brine, the steps of which are as follows:

[0025] a. Extract lithium ions by placing aluminum-based lithium adsorbent in brine;

[0026] b. Desorb the aluminum-based lithium adsorbent after adsorbing lithium ions with ultrapure water to obtain a lithium ion solution.

[0027] Furthermore, in step a, the adsorption temperature is 30℃~60℃, the adsorption time is 30~120 minutes, and the adsorption liquid-solid ratio is 30~200mL / g;

[0028] Furthermore, in step b, the desorption temperature is 30℃~60℃, the desorption time is 3~9 hours, the number of desorption cycles is 1~3, and the desorption liquid-to-solid ratio is 100~200mL / g.

[0029] The beneficial effects of this invention are as follows:

[0030] 1. In terms of preparation method, aluminum-based lithium adsorbents are prepared by in-situ conversion of metal-organic framework precursors. Aluminum-based adsorbents can be prepared using different alkaline solutions of lithium compounds, and the interlayer ions of the aluminum-based adsorbents can also be controlled. Its chemical formula is LiX·2Al(OH)3·n H2O, where X can be Cl... - CO3 2- OH - ;

[0031] 2. In terms of adsorption process, lithium is extracted from salt lake brine by adsorption method. During the desorption process, deionized water is often used as the desorption liquid. During the adsorption process, the adsorption capacity can reach 6.8 mg / g, with low dissolution rate and circulation and selection functions. Attached Figure Description

[0032] Figure 1 This is a scanning electron microscope image of the metal-organic framework precursor of Example 1 of the present invention;

[0033] Figure 2 This is an X-ray powder diffraction pattern of the metal-organic framework precursor of Example 1 of the present invention;

[0034] Figure 3 This is a scanning electron microscope image of the aluminum-based lithium adsorbent in Example 1 of the present invention;

[0035] Figure 4 This is a scanning electron microscope image of the aluminum-based lithium adsorbent in Example 2 of the present invention;

[0036] Figure 5 This is a scanning electron microscope image of the aluminum-based lithium adsorbent in Example 3 of the present invention;

[0037] Figure 6 The X-ray powder diffraction patterns are for Examples 1-3 of the present invention. Detailed Implementation

[0038] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. 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.

[0039] Example 1

[0040] The preparation method of aluminum-based lithium adsorbent includes the following steps:

[0041] (1) 1.18 g of aluminum nitrate was dissolved in 20 mL of ultrapure water to obtain solution A, and 0.56 g of 2-aminoterephthalic acid was dissolved in 20 mL of N,N-dimethylformamide to obtain solution B. Solutions A and B were thoroughly mixed and sonicated to obtain a mixed solution. The mixed solution was then added to a reaction vessel and placed in an oven at 150 °C for 24 hours. After cooling, the mixture was centrifuged, washed three times with ethanol, and dried in a vacuum oven at 120 °C for 12 hours to obtain the metal-organic framework precursor MIL-53-NH2(Al). Its scanning electron microscope image and X-ray powder diffraction pattern are shown below. Figure 1 and Figure 2 As shown.

[0042] (2) Take 1g of dried MIL-53-NH2(Al) sample and place it in a 100mL capped screw-top glass bottle. Dissolve it in ultrapure water by sonication. Add 0.27g of lithium hydroxide while stirring, and react at 75℃ for 8 hours. After aging for 12 hours, centrifuge, wash three times with ultrapure water, and dry at 60℃ for 12 hours. Desorb the aluminum-based adsorbent in water at 60℃ for 3 hours, then centrifuge and dry at 60℃ to obtain the finished aluminum-based lithium adsorbent of this embodiment. Its scanning electron microscope image and X-ray powder diffraction pattern are shown below. Figure 3 and Figure 6 As shown.

[0043] Example 2

[0044] The preparation method of the aluminum-based lithium adsorbent is the same as in Example 1, and step (2) is as follows:

[0045] 1 g of dried MIL-53-NH2(Al) sample was placed in a 100 mL capped screw-top glass bottle and dissolved in ultrapure water by ultrasonication. Under stirring, 0.47 g of lithium chloride and 0.45 g of sodium hydroxide were added, and the mixture was reacted at 75 °C for 8 hours. After aging for 12 hours, the sample was centrifuged, washed three times with ultrapure water, and dried at 60 °C for 12 hours. The aluminum-based adsorbent was desorbed in water at 60 °C for 3 hours, then centrifuged and dried at 60 °C to obtain the finished aluminum-based lithium adsorbent of this embodiment. Its scanning electron microscope (SEM) image and X-ray powder diffraction pattern are shown below. Figure 4 and Figure 6 As shown.

[0046] Example 3

[0047] The preparation method of the aluminum-based lithium adsorbent is the same as in Example 1, and step (2) is as follows:

[0048] 1 g of dried MIL-53-NH2(Al) sample was placed in a 100 mL capped screw-top glass bottle and dissolved in ultrapure water by ultrasonication. Under stirring, 0.47 g of lithium chloride and 2.22 g of urea were added, and the mixture was reacted at 75 °C for 8 hours. After aging for 12 hours, the sample was centrifuged, washed three times with ultrapure water, and dried at 60 °C for 12 hours. The aluminum-based adsorbent was desorbed in water at 60 °C for 3 hours, then centrifuged and dried at 60 °C to obtain the finished aluminum-based lithium adsorbent of this embodiment. Its scanning electron microscope (SEM) image and X-ray powder diffraction (XRD) pattern are shown below. Figure 5 and Figure 6 As shown.

[0049] Example 4

[0050] Extraction efficiency test

[0051] The aluminum-based lithium adsorbents prepared in Examples 1-3 were used for lithium extraction. Adsorption and desorption experiments were carried out in a shaker with a shaking speed of 150 rpm and a temperature of 60 °C. Specifically, 0.5 g of aluminum-based lithium adsorbent was weighed and placed in 100 mL of 600 mg / L lithium chloride solution for adsorption for 120 minutes, and its adsorption capacity was calculated. The adsorbed aluminum-based lithium adsorbent was then desorbed with ultrapure water at 60 °C, and the desorption rate was calculated. The results are shown in Table 1.

[0052] Table 1. Adsorption capacity and desorption rate of aluminum-based lithium adsorbents in Examples 1-3

[0053]

[0054] Example 5

[0055] Adsorption temperature investigation experiment

[0056] The adsorption temperature was investigated using the aluminum-based lithium adsorbent in Example 1. The adsorption temperatures were 30, 45, and 60°C, the liquid-to-solid ratio was 100, the adsorption time was 120 minutes, and the adsorbent was a 600 mg / L lithium chloride solution. The desorption liquid-to-solid ratio was 100, the desorption temperature was 60°C, the desorption time was 3 hours, and the desorption was performed once. The results are shown in Table 2.

[0057] Table 2 Adsorption capacity and desorption rate

[0058]

[0059] Example 6

[0060] Adsorption liquid-solid ratio condition investigation experiment

[0061] The adsorption conditions of the aluminum-based lithium adsorbent prepared in Example 1 were investigated. The adsorption temperature was 60°C, the adsorption liquid-to-solid ratio was 30, 50, 100 and 200, the adsorption time was 120 minutes, and the adsorption liquid was a 600 mg / L lithium chloride solution. The desorption liquid-to-solid ratio was 100, the desorption temperature was 60°C, the desorption time was 3 hours, and the desorption was performed once. The results are shown in Table 3.

[0062] Table 3 Adsorption capacity and desorption rate

[0063]

[0064] Example 7

[0065] Adsorption time study experiment

[0066] The adsorption time was investigated using the aluminum-based lithium adsorbent prepared in Example 1 under the following conditions: adsorption temperature was 60°C, adsorption liquid-to-solid ratio was 200, adsorption time was 30, 60, and 120 minutes, and the adsorption liquid was a 600 mg / L lithium chloride solution; desorption liquid-to-solid ratio was 100, desorption temperature was 60°C, desorption time was 3 hours, and desorption was performed once; the results are shown in Table 4.

[0067] Table 4 Adsorption capacity and desorption rate

[0068]

[0069] Example 8

[0070] Lithium chloride concentration investigation experiment

[0071] The concentration of lithium chloride in the adsorption solution was investigated using the aluminum-based lithium adsorbent prepared in Example 1. The adsorption temperature was 60℃, the adsorption liquid-to-solid ratio was 200, and the adsorption time was 120 minutes. Lithium chloride solutions with concentrations of 200, 300, 400, 500, and 600 mg / L were used as the adsorption solution. The desorption liquid-to-solid ratio was 100, the desorption temperature was 60℃, the desorption time was 3 hours, and the desorption was performed once. The results are shown in Table 5.

[0072] Table 5 Adsorption capacity and desorption rate

[0073]

[0074] Example 9

[0075] Desorption liquid-solid ratio investigation experiment

[0076] The aluminum-based lithium adsorbent prepared in Example 1 was used to conduct an experiment to investigate the desorption liquid-to-solid ratio under the following conditions: adsorption temperature 60℃, adsorption liquid-to-solid ratio 200, adsorption time 120 minutes, and 600 mg / L lithium chloride solution as the adsorbent; desorption liquid-to-solid ratios of 100, 50, and 30, desorption temperature 60℃, desorption time 3 hours, and desorption was performed once; the results are shown in Table 6.

[0077] Table 6 Adsorption capacity and desorption rate

[0078] 100 60 3 1 96 50 60 3 1 85 30 60 3 1 76

[0079] Example 10

[0080] Desorption temperature investigation experiment

[0081] The desorption temperature was investigated using the aluminum-based lithium adsorbent prepared in Example 1. The adsorption temperature was 60°C, the adsorption liquid-to-solid ratio was 200, the adsorption time was 120 minutes, and the adsorption liquid was a 600 mg / L lithium chloride solution. The desorption liquid-to-solid ratio was 100, the desorption temperature was 30, 45, and 60°C, the desorption time was 3 hours, and the desorption was performed once. The results are shown in Table 7.

[0082] Table 7 Adsorption capacity and desorption rate

[0083] 100 30 3 1 93 100 45 3 1 95 100 60 3 1 96

[0084] Example 11

[0085] Desorption time study experiment

[0086] The desorption time was investigated under the following conditions using the aluminum-based lithium adsorbent prepared in Example 1: adsorption temperature was 60°C, adsorption liquid-to-solid ratio was 200, adsorption time was 120 minutes, and the adsorption liquid was a 600 mg / L lithium chloride solution; desorption liquid-to-solid ratio was 100, desorption temperature was 60°C, desorption time was 3, 6, and 9 hours, and desorption was performed once; the results are shown in Table 8.

[0087] Table 8 Adsorption capacity and desorption rate

[0088] 100 60 3 1 96 100 60 6 1 97 100 60 9 1 97

[0089] Example 12

[0090] Desorption count test experiment

[0091] The aluminum-based lithium adsorbent prepared in Example 1 was used to investigate the number of desorption cycles under the following conditions: adsorption temperature was 60°C, adsorption liquid-to-solid ratio was 200, adsorption time was 120 minutes, and the adsorption liquid was a 600 mg / L lithium chloride solution; desorption liquid-to-solid ratio was 100, desorption temperature was 60°C, desorption time was 3 hours, and desorption was performed 1, 2, and 3 times. The results are shown in Table 9.

[0092] Table 9 Adsorption capacity and desorption rate

[0093] 100 60 3 1 96 100 60 3 2 98 100 60 3 3 100

[0094] Example 13

[0095] Simulated brine lithium extraction experiment

[0096] The aluminum-based lithium adsorbent prepared in Example 1 was used to conduct a simulated brine lithium extraction experiment. The adsorption temperature was 60℃, the liquid-to-solid ratio was 30, and the adsorption time was 120 minutes. The results are shown in Table 10.

[0097] Table 10 Results of simulated brine lithium extraction experiments

[0098] <![CDATA[Concentration before adsorption C₀ (mg / L)]]> 560 1000 552 585 654 <![CDATA[Concentration after adsorption C e (mg / L)]]> 506 980 548 578 640 Adsorption capacity Qe (mg / g) 1.74 0.64 0.13 0.24 0.47 <![CDATA[Partition coefficient Kd M (mL / g)]]> 3.44 0.65 0.23 0.41 0.70

Claims

1. A method for preparing an aluminum-based lithium adsorbent, characterized in that, Includes the following steps: S1. Dissolve aluminum nitrate and 2-aminoterephthalic acid in ultrapure water and N,N-dimethylformamide, respectively; S2. Thoroughly mix the two solutions in S1, then add the mixture to the reaction vessel and heat to react; S3. Centrifuge the product obtained in S2, wash it with ethanol, and then dry it under vacuum. S4. Disperse the product obtained in S3 in ultrapure water, add an alkaline solution of lithium compound while stirring, and continue heating and stirring until the reaction is complete. S5. Stop stirring and allow aging to obtain precipitate. Centrifuge the precipitate, wash it with ultrapure water, and then heat and dry it. S6. The product obtained in S5 is desorbed with deionized water, centrifuged, and dried to obtain aluminum-based lithium adsorbent.

2. The method for preparing the aluminum-based lithium adsorbent according to claim 1, characterized in that, The molar ratio of aluminum nitrate and p-2-aminoterephthalic acid in S1 is 2:1 to 1:

2.

3. The method for preparing the aluminum-based lithium adsorbent according to claim 1, characterized in that, The reaction temperature described in S2 is 120–140°C, and the reaction time is 20–24 hours; The centrifugation speed in S3 is 8000-10000 rpm, the washing is done three times with ethanol, the vacuum drying temperature is 100-150℃, and the drying time is 8-12 hours. The heating temperature described in S4 is 75–95°C, and the reaction time is 8–16 hours; The aging time mentioned in S5 is 12 to 24 hours; the centrifugal speed is 8000 to 10000 rpm; the drying temperature is 60 to 90°C; and the drying time is 12 to 24 hours. The desorption temperature described in S6 is 30℃~60℃, the desorption time is 3~9 hours, the centrifugation speed is 8000~10000 rpm, and the drying temperature is 60~90℃.

4. The method for preparing the aluminum-based lithium adsorbent according to claim 1, characterized in that, The amount of product obtained in S3 described in S4 is 0.5–1.0 g, and the lithium compound content in the alkaline solution of the lithium compound is 5–15 mmol.

5. The method for preparing the aluminum-based lithium adsorbent according to claim 1 or 4, characterized in that, The alkaline solution of the lithium compound is any one of lithium hydroxide solution, sodium hydroxide solution of lithium chloride, or urea solution of lithium chloride.

6. The method for preparing the aluminum-based lithium adsorbent according to claim 1, characterized in that, The washing described in S5 involves centrifuging and washing three times with ultrapure water.

7. An aluminum-based lithium adsorbent, characterized in that, It is prepared by the preparation method according to any one of claims 1 to 6.

8. The application of the aluminum-based lithium adsorbent of claim 7 in lithium extraction from brine.

9. The application of the aluminum-based lithium adsorbent according to claim 8 in lithium extraction from brine, characterized in that, The steps are as follows: a. Extract lithium ions by placing aluminum-based lithium adsorbent in brine; b. Desorb the aluminum-based lithium adsorbent after adsorbing lithium ions with ultrapure water to obtain a lithium ion solution.

10. The application of the aluminum-based lithium adsorbent according to claim 9 in lithium extraction from brine, characterized in that, In step a, the adsorption temperature is 30℃~60℃, the adsorption time is 30~120 minutes, and the adsorption liquid-solid ratio is 30~200 mL / g; The desorption temperature in step b is 30℃~60℃, the desorption time is 3~9 hours, the number of desorption cycles is 1~3, and the desorption liquid-solid ratio is 100~200 mL / g.

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