A "hollow-mesoporous" microreactor for extracting lithium and a preparation method and application thereof

Abstract

This invention belongs to the field of lithium extraction technology from salt lake brine, specifically relating to a hollow-mesoporous microreactor for lithium extraction, its preparation method, and its application. Addressing the problems of solvent loss and poor adsorption selectivity of porous materials in the existing TBP-sulfonated kerosene-ferric chloride extraction system, this invention utilizes the selective complexation ability of the TBP-sulfonated kerosene-ferric chloride system to obtain Na[FeCl4·2TBP] molecules with high selectivity for lithium ions. These molecules are then confined within a hollow-mesoporous material to prepare an organic adsorption nanomaterial for lithium extraction, namely the hollow-mesoporous microreactor. When applied to lithium resource extraction from salt lake brine, this material exhibits good selectivity and high adsorption capacity for lithium ions.

Description

Technical Field

[0001] This invention belongs to the field of lithium extraction technology from salt lake brine, specifically relating to a hollow-mesoporous microreactor for lithium extraction, its preparation method, and its application. Background Technology

[0002] Lithium is a crucial energy material and strategic resource for the 21st century. This lightest alkali metal plays a vital role in numerous processes, including rechargeable batteries, thermonuclear fusion, and pharmaceuticals. Consequently, global demand for lithium resources continues to increase. Currently, lithium resources mainly originate from ores and brines, and separating lithium from water resources containing mixed metal ions is a critical process in lithium extraction. However, my country possesses numerous salt lakes with extremely rich brine lithium resources, boasting enormous reserves. These resources typically exhibit a high magnesium-to-lithium ratio. According to the diagonal principle, since Li... + With Mg 2+ Because they have similar properties, the separation process is relatively difficult.

[0003] Magnesium in brine can affect lithium extraction. Currently, the main lithium extraction technologies from salt lake brine include precipitation, membrane separation, solvent extraction, and adsorption. Precipitation is effective for separating lithium ions when magnesium and lithium levels are low, but it is not used when magnesium and lithium levels are high. Membrane separation is a well-established method for ion separation, but it typically only separates ions of different valence states. Solvent extraction offers advantages such as high throughput, high selectivity, fine separation, and energy efficiency, and is considered a promising method; however, this system suffers from significant dissolution losses and the presence of a third phase.

[0004] Adsorption is an effective method for separating lithium and has been successfully applied to the recovery of lithium from salt lake brines. Adsorption is widely used to separate different ions in liquids and is known for its simplicity, high recovery rate, and large processing capacity. The adsorption method utilizes Li extraction adsorbents to separate Li... + Selective adsorption is performed, followed by elution to remove Li + Elution, thereby achieving the removal of Li from salt lake brine + Selective separation is achieved. Currently, most commonly used adsorbents are ion sieve adsorbents, but they suffer from solubility loss during preparation and regeneration. However, organic adsorbent materials can not only solve the problem of organic extractant / solvent loss but also be recycled. Therefore, designing and searching for a novel organic adsorbent material as a lithium-ion adsorbent to overcome its shortcomings in practical applications is a key focus and future research trend in lithium-ion adsorbent material research. Summary of the Invention

[0005] To address the problems of existing lithium extraction processes requiring large amounts of extractants, co-extractants, high concentrations of acid, and solvent loss of lithium adsorbents during preparation and regeneration, this invention provides a hollow-mesoporous microreactor for lithium extraction, along with its preparation method and applications. Lithium extraction using Na[FeCl4·2TBP] molecules is a method within solvent extraction, involving two-phase mixing and separation during extraction, back-extraction, and regeneration. However, solvent loss is inevitable during separation. The hollow-mesoporous microreactor synthesized in this invention confines Na[FeCl4·2TBP] molecules within a hollow-mesoporous material, eliminating the two-phase separation process during adsorption and desorption, thus effectively solving the solvent loss problem in lithium extraction.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] A method for preparing a hollow-mesoporous microreactor for lithium extraction includes the following steps:

[0008] Step 1: Mix tributyl phosphate (TBP), sulfonated kerosene, ferric chloride and hydrochloric acid evenly, stir, let stand to separate, and retain the organic phase; then add the aqueous phase to the organic phase, stir, let stand to separate, and retain the organic phase; finally add sodium hydroxide solution to the organic phase, stir, let stand to separate, and retain the organic phase to obtain Na[FeCl4·2TBP] lithium molecules.

[0009] Step 2: Dissolve hexadecyltrimethylammonium bromide in an ethanol-water solution containing concentrated ammonia, stir vigorously, then add tetraethyl orthosilicate, continue stirring, and centrifuge; add the separated product to water, stir, and centrifuge; then transfer the separated product to an ethanol solution containing hydrochloric acid, stir, and centrifuge to obtain a white product;

[0010] Step 3: Confine the lithium molecules obtained in Step 1 into the white product obtained in Step 2, vacuum inject, remove the solvent by rotary evaporation, and vacuum dry to obtain a "hollow-mesoporous" microreactor.

[0011] Furthermore, in step 1, the amount of tributyl phosphate and sulfonated kerosene used is 50-60 mL, the amount of ferric chloride used is 25-30 mL, and the amount of hydrochloric acid used is 11-14 mL.

[0012] Furthermore, the amount of aqueous phase used in step 1 is 5-6 mL.

[0013] Furthermore, the amount of sodium hydroxide used in step 1 is 1 to 3.5 mL.

[0014] Further, in step 2, the amount of hexadecyltrimethylammonium bromide used is 0.1-0.35 g, the amount of concentrated ammonia water used is 0.5-1 mL, the volume ratio of ethanol to water in the ethanol aqueous solution is 0.46-0.75, and the amount of tetraethyl orthosilicate used is 1-2 mL.

[0015] Furthermore, in step 2, the temperature at which the separated product is added to water and stirred is 25–90°C, and the time is 2–148 hours.

[0016] Furthermore, in step 2, the amount of ethanol used in the ethanol solution containing hydrochloric acid is 100-120 mL.

[0017] A hollow-mesoporous microreactor prepared by the method described above is a hollow-mesoporous nano-adsorbent material that exhibits a finite-domain effect on lithium extraction molecules Na[FeCl4·2TBP].

[0018] An application of the "hollow-mesoporous" microreactor described above, used as a lithium-ion adsorption material for lithium extraction from salt lake brine.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0020] The hollow-mesoporous microreactor prepared in this invention is a lithium-ion nanomaterial with simple preparation process, good selectivity, stable cycle performance, high adsorption rate, and simple magnesium-lithium separation. This material achieves lithium-ion adsorption and desorption by confining lithium extraction molecules Na[FeCl4·2TBP] within the hollow-mesoporous nanomaterial, utilizing the selective complexing ability of the TBP-sulfonated kerosene-ferric chloride system for lithium ions and the porous structure of the hollow-mesoporous nanomaterial. This solves the problems of solvent loss and poor adsorption selectivity of porous materials in the existing TBP-sulfonated kerosene-ferric chloride extraction process. Attached Figure Description

[0021] Figure 1 This is a flowchart illustrating the preparation route of the "hollow-mesoporous" microreactor in Example 1;

[0022] Figure 2 This is a SEM image of the "hollow-mesoporous" microreactor prepared in Example 2. Detailed Implementation

[0023] To facilitate understanding of the present invention, a more comprehensive description will be given below. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0024] Preparation Example 1

[0025] A method for preparing a hollow-mesoporous microreactor for lithium extraction includes the following steps:

[0026] Step 1: Under normal temperature conditions, mix 50 mL of tributyl phosphate (TBP) / sulfonated kerosene mixed solution, 25 mL of ferric chloride and 11 mL of hydrochloric acid, stir continuously for 0.5 h, let stand to separate, and retain the organic phase; then add 5 mL of aqueous phase to the organic phase, continue stirring, let stand to separate, and retain the organic phase; finally, add 1 mL of sodium hydroxide solution to the organic phase, stir, let stand to separate, and retain the organic phase to obtain Na[FeCl4·2TBP] lithium molecules;

[0027] Step 2: At 35°C, dissolve 0.1 g of hexadecyltrimethylammonium bromide in 110 mL of an ethanol-water solution containing 0.5 mL of concentrated ammonia (ethanol to water volume ratio of 0.5), stir vigorously for a certain period of time, then add 1 mL of tetraethyl orthosilicate, continue stirring, and centrifuge; add the separated product to 160 mL of water, stir at 70°C for 12 h, and centrifuge; then transfer the separated product to 120 mL of an ethanol solution containing high-concentration hydrochloric acid (240 μL), stir magnetically, and centrifuge to obtain a white product;

[0028] Step 3: The lithium molecules obtained in Step 1 are confined into the white product obtained in Step 2, vacuum-injected, solvent removed by rotary evaporation, and vacuum dried to finally obtain particles with a diameter of approximately 550 nm, a shell thickness of approximately 100 nm, and a specific surface area of ​​1032.88 m². 2 g -1 Hollow-mesoporous microreactors with a mesopore size of 3.7 nm.

[0029] Preparation Example 2

[0030] Step 1: Under normal temperature conditions, mix 60 mL of tributyl phosphate (TBP) / sulfonated kerosene mixed solution, 30 mL of ferric chloride and 14 mL of hydrochloric acid, stir continuously for 1 h, let stand to separate, and retain the organic phase; then add 6 mL of aqueous phase to the organic phase, continue stirring, let stand to separate, and retain the organic phase; finally, add 3.5 mL of sodium hydroxide solution to the organic phase, stir, let stand to separate, and retain the organic phase to obtain Na[FeCl4·2TBP] lithium molecules;

[0031] Step 2: At 35°C, dissolve 0.15 g of hexadecyltrimethylammonium bromide in 100 mL of an ethanol-water solution containing 0.5 mL of concentrated ammonia (ethanol to water volume ratio of 0.5), stir vigorously for a certain period of time, then add 1 mL of tetraethyl orthosilicate, continue stirring, and centrifuge; add the separated product to 160 mL of water, stir at 90°C for 12 h, and centrifuge; then transfer the separated product to 120 mL of an ethanol solution containing high-concentration hydrochloric acid (240 μL), stir magnetically, and centrifuge to obtain a white product;

[0032] Step 3: The lithium molecules obtained in Step 1 are confined into the white product obtained in Step 2, vacuum-filled, the solvent is removed by rotary evaporation, and then vacuum-dried to finally obtain particles with a particle size of approximately 530 nm, a shell thickness of approximately 90 nm, and a specific surface area of ​​1062.54 m². 2 g -1 Hollow-mesoporous microreactors with a mesopore size of 4.2 nm.

[0033] Application Example 1

[0034] The hollow-mesoporous microreactor obtained in Preparation Example 1 was applied to the extraction of lithium ions from a lithium-containing simulated brine. + With a concentration of 50 mg / L and a Mg / Li ratio of 50, an adsorption-desorption experiment was conducted. The adsorption reached equilibrium within 50 minutes, with a maximum adsorption capacity of 32.48 mg / g and a desorption rate of 94.3%. After five cycles, the adsorption rate of the adsorbent remained at 96.58%.

[0035] Application Example 2

[0036] The hollow-mesoporous microreactor obtained in Preparation Example 1 was applied to the extraction of lithium ions from a lithium-containing simulated brine. + With a concentration of 100 mg / L and a Mg / Li ratio of 100, the adsorption experiment showed that the adsorption reached equilibrium in 50 minutes. The maximum adsorption capacity was 33.52 mg / g, and the desorption rate reached 92.8%. After 5 cycles, the adsorption rate of the adsorbent was still maintained at 96.01%.

[0037] Application Example 3

[0038] The hollow-mesoporous microreactor obtained in Preparation Example 2 was applied to lithium ion extraction from a lithium-containing simulated brine. + With a concentration of 200 mg / L and a Mg / Li ratio of 200, an adsorption experiment was conducted. The adsorption reached equilibrium within 50 minutes, and the maximum adsorption capacity was measured to be 31.67 mg / g. The desorption rate reached 95.6%, and the adsorption rate of the adsorbent remained at 97.61% after 5 cycles.

[0039] The above description is only for better explaining the embodiments of the present invention and is not intended to limit them. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention shall fall within the scope of the present invention.

Claims

1. A method for preparing a hollow-mesoporous microreactor for lithium extraction, characterized in that, Includes the following steps: Step 1: Mix tributyl phosphate, sulfonated kerosene, ferric chloride and hydrochloric acid evenly, stir, let stand to separate, and retain the organic phase; then add the aqueous phase to the organic phase, stir, let stand to separate, and retain the organic phase; finally add sodium hydroxide solution to the organic phase, stir, let stand to separate, and retain the organic phase to obtain Na[FeCl4·2TBP] lithium molecules; Step 2: Dissolve hexadecyltrimethylammonium bromide in an ethanol-water solution containing concentrated ammonia, stir vigorously, add tetraethyl orthosilicate, continue stirring, and centrifuge to separate. Add the separated product to water, stir, and centrifuge. The separated product was then transferred to an ethanol solution containing hydrochloric acid, stirred, and centrifuged to obtain a white product. Step 3: Confine the lithium molecules obtained in Step 1 into the white product obtained in Step 2, vacuum inject, remove the solvent by rotary evaporation, and vacuum dry to obtain a "hollow-mesoporous" microreactor.

2. The preparation method according to claim 1, characterized in that, In step 1, the amount of tributyl phosphate and sulfonated kerosene used is 50-60 mL, the amount of ferric chloride used is 25-30 mL, and the amount of hydrochloric acid used is 11-14 mL.

3. The preparation method according to claim 1, characterized in that, The amount of aqueous phase used in step 1 is 5-6 mL.

4. The preparation method according to claim 1, characterized in that, The amount of sodium hydroxide used in step 1 is 1 to 3.5 mL.

5. The preparation method according to claim 1, characterized in that, In step 2, the amount of hexadecyltrimethylammonium bromide used is 0.1-0.35 g, the amount of concentrated ammonia water used is 0.5-1 mL, the volume ratio of ethanol to water in the ethanol-water solution is 0.46-0.75, and the amount of tetraethyl orthosilicate used is 1-2 mL.

6. The preparation method according to claim 1, characterized in that, In step 2, the separated product is added to water and stirred at a temperature of 25–90°C for 2–148 hours.

7. The preparation method according to claim 1, characterized in that, In step 2, the amount of ethanol used in the ethanol solution containing hydrochloric acid is 100-120 mL.

8. A hollow-mesoporous microreactor prepared by the preparation method according to any one of claims 1 to 7, characterized in that, It is a "hollow-mesoporous" nano-adsorbent material that exhibits the finite-domain effect of lithium extraction molecules Na[FeCl4·2TBP].

9. An application of the "hollow-mesoporous" microreactor as described in claim 8, characterized in that, It is used as a lithium-ion adsorption material for lithium extraction from salt lake brine.

Images