Lithium ion sieve adsorbent, preparation method and application thereof

Abstract

This invention belongs to the field of lithium extraction technology from salt lakes, specifically relating to a lithium-ion sieve adsorbent, its preparation method, and its application. This invention forms a polyionic liquid with phosphate groups on a manganese-based ion sieve material. The polyionic liquid not only acts as a binder but also plays a role in lithium extraction, avoiding the problem of decreased lithium extraction performance caused by the binder covering the active adsorption sites of the ion sieve. It can increase the lithium adsorption capacity while reducing the manganese dissolution rate.

Description

Technical Field

[0001] This invention belongs to the field of lithium extraction technology from salt lakes, specifically relating to a lithium-ion sieve adsorbent, its preparation method, and its application. Background Technology

[0002] With the rapid development of electronic products and new energy vehicles, the demand for lithium resources is increasing year by year. However, the supply of lithium resources is limited, and the contradiction between supply and demand has made the efficient development and extraction of lithium resources a research hotspot. Currently, lithium resources in salt lake brines are more abundant than those in ores. Furthermore, lithium extraction from ores generally suffers from high energy consumption and high pollution, making salt lake brine extraction a primary method for obtaining lithium resources. Currently, the development and utilization of lithium resources in salt lake brines mainly utilizes methods such as ion exchange and adsorption, extraction, nanofiltration, selective electrodialysis, and electrochemistry. Among these, the adsorbent method utilizes adsorbents to selectively adsorb lithium ions. After adsorption, the adsorbents can be desorbed by acid washing, thus separating lithium ions from other ions. This method has advantages such as easy regeneration, simple operation, and high recovery rate, making it one of the most promising lithium extraction methods.

[0003] Lithium extraction adsorbents from salt lakes mainly include aluminum-based, manganese-based, and titanium-based adsorbents. Currently, all manganese-based ion sieves are in powder form, exhibiting insufficient permeability and poor flowability, generally resulting in high dissolution rates, low lithium recovery rates, and reduced adsorption capacity during elution. Current methods to improve ion sieve morphology include granulation, membrane fabrication, foaming, nanofiber membrane fabrication, membrane electrode assembly, and magnetization. Granulation is the most commonly used method. Granulation typically involves directly mixing the precursor with a binder, or cross-linking the precursor in a polymer solution to obtain granular ion sieve adsorbents. However, granulation reduces the adsorption capacity in actual salt lake brine because the binder or polymer can clog adsorption sites, reducing the number of active sites for lithium adsorption.

[0004] Therefore, there is an urgent need to improve the preparation process of manganese-based lithium ion sieve adsorbents in order to enhance the stability of the ion sieve adsorbents and increase the lithium adsorption capacity while reducing the manganese dissolution rate.

[0005] In view of this, the present invention is proposed. Summary of the Invention

[0006] The present invention aims to provide a lithium-ion sieve adsorbent, its preparation method and application, with the goal of reducing the dissolution rate of manganese while increasing the adsorption capacity of lithium.

[0007] To achieve the above-mentioned objectives of this invention, the following technical solutions can be adopted:

[0008] In a first aspect, the solution provided by the present invention includes a lithium ion sieve adsorbent, comprising a manganese-based ion sieve material, wherein a polyionic liquid is bonded to the manganese-based ion sieve material.

[0009] In particular, the anions in polyionic liquids carry P=O groups.

[0010] In some embodiments of the present invention, the lithium-ion sieve adsorbent is obtained by polymerizing a vinyl-modified adsorbent and an ionic liquid monomer; wherein the ionic liquid monomer contains phosphate groups and vinyl groups; the vinyl-modified adsorbent includes a manganese-based ion sieve material, on which a vinyl-containing silane coupling agent is bonded.

[0011] Preferably, the ionic liquid monomer is selected from at least one of 1-vinyl-3-ethylimidazolium dibutyl phosphate and 1-vinyl-3-ethylimidazolium diethyl phosphate;

[0012] Preferably, the manganese-based ion sieve material is selected from at least one of MnO2·0.5H2O, λ-MnO2, and MnO2·0.3H2O;

[0013] Preferably, in the lithium-ion sieve adsorbent, the mass percentage of phosphate groups is 15%-35%;

[0014] Preferably, the silane coupling agent is selected from at least one of vinyltrimethoxysilane, vinyltriethoxysilane, 3-methacryloylpropyltrimethoxysilane, vinyltriacetoxysilane, ethylenetriisopropenyloxysilane, methylvinyldimethoxysilane, methylvinyldiethoxysilane, methacryloxytrimethoxysilane, methacryloxytriethoxysilane, and tetramethyldivinyldisiloxane.

[0015] Secondly, the present invention also provides a method for preparing a lithium-ion sieve adsorbent, comprising: mixing and reacting a vinyl-modified adsorbent with an ionic liquid monomer containing phosphate groups and vinyl groups to polymerize the ionic liquid monomer;

[0016] Among them, the vinyl-modified adsorbent includes manganese-based ion sieve materials, on which a vinyl-containing silane coupling agent is bonded.

[0017] In some embodiments of the present invention, the following are included: modifying a manganese-based ion sieve material with a vinyl-containing silane coupling agent to obtain a vinyl-modified adsorbent, and mixing and reacting the vinyl-modified adsorbent with an ionic liquid monomer.

[0018] Preferably, the preparation process of the vinyl-modified adsorbent includes: mixing manganese-based ion sieve material, silane coupling agent and solvent, and reacting at 40℃-85℃ for 12h-24h; more preferably, the silane coupling agent and solvent are mixed to obtain a silane coupling agent solution, and the manganese-based ion sieve material and the silane coupling agent solution are mixed, wherein the concentration of the silane coupling agent solution is 0.5wt%-10wt%.

[0019] Preferably, the mass ratio of manganese-based ion sieve material to silane coupling agent is 1:(0.4-0.8); more preferably, the particle size of manganese-based ion sieve material is 800 mesh-1000 mesh.

[0020] Preferably, the solvent is a mixed solvent formed by an organic solvent and water, wherein the mass fraction of water in the mixed solvent is 5%-15%; more preferably, the organic solvent is selected from at least one of methanol, ethanol, isopropanol, dimethyl sulfoxide and N-methylpyrrolidone.

[0021] Preferably, after the reaction between the manganese-based ion sieve material and the silane coupling agent is completed, solid-liquid separation is performed to obtain solid material, and the solid material is washed and dried to obtain vinyl-modified adsorbent.

[0022] In some embodiments of the present invention, a vinyl-modified adsorbent, a solvent, an ionic liquid monomer, a crosslinking agent, and an initiator are mixed and subjected to a polymerization reaction at 65°C-75°C for 6-24 hours.

[0023] Preferably, the mass ratio of the vinyl-modified adsorbent to the ionic liquid monomer is (5-15):1;

[0024] Preferably, the crosslinking agent is selected from at least one of ethylene glycol dimethacrylate and divinylbenzene; the mass ratio of the crosslinking agent to the ionic liquid monomer is (10-15):100;

[0025] Preferably, the initiator is selected from at least one of azobisisobutyronitrile and benzoyl peroxide; the mass ratio of initiator to ionic liquid monomer is (1.0-1.5):100.

[0026] In some embodiments of the present invention, the vinyl-modified adsorbent and solvent are first mixed, then mixed with ionic liquid monomer, crosslinking agent and initiator, and an inert gas is introduced for 30 min-60 min, and then the polymerization reaction is carried out under closed conditions.

[0027] Preferably, the solvent is selected from at least one of N,N-dimethylformamide and N-methylpyrrolidone; the amount of solvent used per gram of vinyl-modified adsorbent is 1 mL to 3 mL;

[0028] Preferably, after the polymerization reaction is completed, solid-liquid separation is performed to obtain solid material, which is then washed and dried.

[0029] In some embodiments of the present invention, the preparation process of the ionic liquid monomer includes: reacting a phosphoric acid organic compound with a vinyl compound;

[0030] Among them, the phosphoric acid organic compound is selected from at least one of tributyl phosphate and triethyl phosphate;

[0031] The vinyl compound is selected from at least one of 1-vinylimidazolium and 2-dimethylaminoethyl methacrylate;

[0032] Preferably, the reaction temperature of the phosphoric acid organic compound with the vinyl compound is 120℃-160℃, and the reaction time is 10h-20h;

[0033] Preferably, the molar ratio of the phosphoric acid organic compound to the vinyl compound is 1:(0.9-1.1);

[0034] Preferably, after the reaction between the phosphoric acid organic compound and the vinyl compound is complete, extraction and washing are performed; wherein the extractant used in the extraction process is selected from at least one of diethyl ether and ethyl acetate.

[0035] Thirdly, the present invention also provides a lithium extraction method, which uses the lithium-ion sieve adsorbent in any of the above embodiments or the lithium-ion sieve adsorbent prepared by the preparation method in any of the above embodiments to adsorb lithium-containing brine.

[0036] In some embodiments of the present invention, after adsorption is complete, the lithium ion sieve adsorbent is washed in an inorganic acid solution to obtain delithiated lithium ion sieve particles.

[0037] Preferably, the concentration of the inorganic acid solution is 0.6 mol / L-1.1 mol / L, and the mass ratio of the lithium ion sieve adsorbent to the inorganic acid solution is 1:(90-110).

[0038] In some embodiments of the present invention, the method further includes: mixing delithiated lithium-ion sieve particles and phosphoric acid organic compounds, and reacting them at 120°C-160°C for 5-10 hours.

[0039] Preferably, the phosphate-based organic compound is selected from at least one of tributyl phosphate and triethyl phosphate;

[0040] Preferably, the mass ratio of delithiated lithium-ion sieve particles to phosphoric acid organic compounds is 1:(0.2-0.5);

[0041] Preferably, the product is washed after the delithiated lithium-ion sieve particles and the phosphoric acid organic compound have reacted.

[0042] A polyionic liquid with phosphate groups will be formed on a manganese-based ion sieve material. This polyionic liquid can not only act as a binder, but also interact with Li in the brine through specific P=O-Li coordination bonds and Coulomb forces. + By combining the binder with the ion sieve, lithium extraction is achieved, avoiding the problem of decreased lithium extraction performance caused by the binder covering the adsorption active sites of the ion sieve. This method can improve lithium adsorption capacity while reducing manganese dissolution rate. Attached Figure Description

[0043] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0044] Figure 1 A flowchart illustrating the preparation process of the lithium-ion sieve adsorbent provided by this invention;

[0045] Figure 2 Infrared spectra of manganese-based ion sieve particles before and after lithium adsorption. Detailed Implementation

[0046] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0047] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0048] This invention provides a method for preparing a lithium-ion sieve adsorbent; please refer to [reference needed]. Figure 1 This includes the following steps:

[0049] S1, providing ionic liquid monomers

[0050] The ionic liquid monomer contains phosphate groups and vinyl groups, and the specific types are not limited. Ionic liquid monomers containing both of the above groups are suitable for the method provided by the present invention.

[0051] In some embodiments of the present invention, the ionic liquid monomer is selected from at least one of 1-vinyl-3-ethylimidazolium dibutyl phosphate and 1-vinyl-3-ethylimidazolium diethyl phosphate. The ionic liquid monomer can be any one or more of the above, and can be prepared by existing methods or commercially available materials.

[0052] In some embodiments of the present invention, the preparation process of the ionic liquid monomer includes: reacting a phosphoric acid organic compound with a vinyl compound; wherein the phosphoric acid organic compound is selected from at least one of tributyl phosphate and triethyl phosphate, and may be any one or more thereof; the vinyl compound is selected from at least one of 1-vinylimidazole and 2-dimethylaminoethyl methacrylate, and may be any one or more thereof. Taking tributyl phosphate and 1-vinylimidazole as an example, the reaction yields 1-vinyl-3-ethylimidazole dibutyl phosphate salt [VEIm][DBP], and the synthesis reaction is as follows:

[0053]

[0054] In some embodiments of the present invention, the reaction temperature of the phosphoric acid organic compound and the vinyl compound is 120℃-160℃, and the reaction time is 10h-20h. By controlling the reaction temperature and time, the reaction is promoted to proceed fully and the utilization rate of raw materials is improved. Specifically, the reaction temperature can be 120℃, 130℃, 140℃, 150℃, 160℃, etc., and the reaction time can be 10h, 13h, 15h, 18h, 20h, etc.

[0055] Furthermore, the molar ratio of phosphoric acid organic compounds to vinyl compounds is 1:(0.9-1.1), such as 1:0.9, 1:1, 1:1.1, etc., with 1:1 being preferable.

[0056] Furthermore, after the reaction between the phosphoric acid organic compound and the vinyl compound is complete, extraction and washing are performed to remove unreacted phosphoric acid organic compounds and vinyl compounds. The extractant used in the extraction process is selected from at least one of diethyl ether and ethyl acetate, and the extractant can be any one or more of the above.

[0057] S2. Preparation of vinyl-modified adsorbents

[0058] Vinyl-modified adsorbents were prepared by modifying manganese-based ion sieve materials with vinyl-containing silane coupling agents.

[0059] In some embodiments of the present invention, the preparation process of the vinyl-modified adsorbent includes: mixing a manganese-based ion sieve material, a silane coupling agent, and a solvent, and reacting them at 40°C-85°C for 12-24 hours. The reaction temperature and time are controlled to ensure the reaction proceeds fully. During the reaction, the hydrolyzed product of the vinyl-based silane coupling agent has a highly polar hydroxyl group, which can undergo a condensation dehydration reaction with the hydroxyl groups on the surface of the manganese-based ion sieve material to form covalent bonds.

[0060] Specifically, the reaction temperature of manganese-based ion sieve materials and silane coupling agents can be 40℃, 50℃, 60℃, 70℃, 80℃, 85℃, etc., and the reaction time can be 12h, 15h, 18h, 20h, 24h, etc.

[0061] In some embodiments of the present invention, the manganese-based ion sieve material is selected from at least one of MnO2·0.5H2O, λ-MnO2 and MnO2·0.3H2O, and can be any one or more of the above. All of the above manganese-based ion sieve materials are commercially available materials, such as MnO2·0.5H2O purchased from Wanlishi Company's manganese-based ion sieve products.

[0062] Furthermore, the manganese-based ion sieve material has a particle size of 800-1000 mesh. Before the reaction, the manganese-based ion sieve material can be pulverized, specifically using a high-speed pulverizer, to ensure the particle size meets the 800-1000 mesh requirement. This allows for a more complete reaction and prevents excessively large particle sizes from affecting the introduction of vinyl groups. Specifically, the particle size of the manganese-based ion sieve material can be 800 mesh, 850 mesh, 900 mesh, 950 mesh, 1000 mesh, etc.

[0063] In some embodiments of the present invention, the silane coupling agent is selected from at least one of vinyltrimethoxysilane, vinyltriethoxysilane, 3-methacryloylpropyltrimethoxysilane, vinyltriacetoxysilane, ethylenetriisopropenyloxysilane, methylvinyldimethoxysilane, methylvinyldiethoxysilane, methacryloxytrimethoxysilane, methacryloxytriethoxysilane, and tetramethyldivinyldisiloxane. It can be any one or more of the above. All of the above silane coupling agents are commercially available raw materials and can all modify manganese-based ion sieve materials to prepare vinyl-modified adsorbents.

[0064] Furthermore, the mass ratio of manganese-based ion sieve material to silane coupling agent is 1:(0.4-0.8). By adjusting this mass ratio, the amount of vinyl groups introduced can be controlled, thereby controlling the amount of polyionic liquid introduced. Within this range, the lithium adsorption capacity can be further improved. Specifically, the mass ratio of manganese-based ion sieve material to silane coupling agent can be 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, etc.

[0065] In practical operation, the silane coupling agent and solvent are first mixed to obtain a silane coupling agent solution. Then, the manganese-based ion sieve material is mixed with the silane coupling agent solution. The concentration of the silane coupling agent solution is 0.5wt%-10wt%, which allows for sufficient reaction between the manganese-based ion sieve material and the silane coupling agent. Specifically, the concentration of the silane coupling agent solution can be 0.5wt%, 1.0wt%, 3.0wt%, 5.0wt%, 8.0wt%, 10.0wt%, etc.

[0066] In some embodiments of the present invention, the solvent is a mixed solvent formed by an organic solvent and water, wherein the mass fraction of water in the mixed solvent is 5%-15%. Using an organic solvent and water as a mixed solvent can better dissolve the silane coupling agent and promote the reaction. Specifically, the mass fraction of water in the mixed solvent can be 5%, 8%, 10%, 12%, 15%, etc.

[0067] Furthermore, the organic solvent is selected from at least one of methanol, ethanol, isopropanol, dimethyl sulfoxide and N-methylpyrrolidone, and the organic solvent can be any one or more of the above.

[0068] In some embodiments of the present invention, after the reaction between the manganese-based ion sieve material and the silane coupling agent is completed, solid-liquid separation is performed to obtain a solid material. The solid material is then washed and dried to obtain a vinyl-modified adsorbent. The solid-liquid separation method is not limited, and conventional suction filtration can be used. The washing reagent used during washing is not limited and can be an organic alcohol, such as ethanol. The drying temperature is not limited, as long as it can sufficiently remove the organic alcohol reagent from the surface.

[0069] S3, Aggregation

[0070] The vinyl-modified adsorbent prepared in step S2 and the ionic liquid monomer containing phosphate groups and vinyl groups prepared in step S1 are mixed and reacted to polymerize the ionic liquid monomer.

[0071] In practice, the vinyl-modified adsorbent, solvent, ionic liquid monomer, crosslinking agent, and initiator are mixed and polymerized at 65℃-75℃ for 6-24 hours. During polymerization, the vinyl groups on the vinyl-modified adsorbent and the vinyl groups in the ionic liquid monomer react to form a polyionic liquid. Specifically, the polymerization temperature can be 65℃, 70℃, 75℃, etc., and the polymerization time can be 6h, 10h, 15h, 20h, 24h, etc.

[0072] In some embodiments of the present invention, the vinyl-modified adsorbent and solvent can be mixed first, then mixed with the ionic liquid monomer, crosslinking agent, and initiator. An inert gas is then introduced for 30-60 minutes to remove dissolved oxygen from the system. The polymerization reaction is then carried out under closed conditions to prevent oxygen interference. Specifically, the inert gas can be nitrogen, and the inert gas introduction time can be 30, 40, 50, or 60 minutes, etc.

[0073] Furthermore, the mass ratio of the vinyl-modified adsorbent to the ionic liquid monomer is (5-15):1. It is preferable to control the mass ratio of the vinyl-modified adsorbent to the ionic liquid monomer within the above range to ensure the content of the polyionic liquid in the product is within an optimal range and to guarantee the adsorption capacity of the adsorbent. Specifically, the mass ratio of the vinyl-modified adsorbent to the ionic liquid monomer can be 5:1, 8:1, 10:1, 12:1, 15:1, etc.

[0074] In some embodiments of the present invention, the crosslinking agent is selected from at least one of ethylene glycol dimethacrylate and divinylbenzene, and the crosslinking agent can be any one or more of the above. The mass ratio of the crosslinking agent to the ionic liquid monomer is (10-15):100, and the amount of crosslinking agent used is preferably within the above range to promote the polymerization reaction. Specifically, the mass ratio of the crosslinking agent to the ionic liquid monomer can be 10:100, 11:100, 12:100, 13:100, 14:100, 15:100, etc.

[0075] In some embodiments of the present invention, the initiator is selected from at least one of azobisisobutyronitrile (AIBN) and benzoyl peroxide. The initiator can be any one or more of the above. The mass ratio of initiator to ionic liquid monomer is (1.0-1.5):100, and the amount of initiator within the above range can promote the polymerization reaction. Specifically, the mass ratio of initiator to ionic liquid monomer can be 1.0:100, 1.1:100, 1.2:100, 1.3:100, 1.4:100, 1.5:100, etc.

[0076] In some embodiments of the present invention, the solvent is selected from at least one of N,N-dimethylformamide and N-methylpyrrolidone. Any one or more of these solvents can effectively disperse the vinyl-modified adsorbent. The amount of solvent used per gram of vinyl-modified adsorbent is 1 mL to 3 mL, and the amount of solvent within this range is preferable to maintain the concentration of the reactants within an optimal range and improve the reaction rate. Specifically, the amount of solvent used per gram of vinyl-modified adsorbent can be 1 mL, 2 mL, 3 mL, etc., and the amount of solvent can be calculated based on the mass of the vinyl-modified adsorbent.

[0077] Furthermore, after the polymerization reaction is complete, solid-liquid separation is performed to obtain solid material. The solid material is then washed and dried to obtain lithium-ion sieve adsorbent particles. The solid-liquid separation method is not limited and can be a general filtration method; the washing reagent is not limited and can be an organic alcohol, such as methanol, preferably by soaking and washing multiple times with methanol; the drying temperature is not limited and can be used to remove the organic alcohol.

[0078] This invention also provides a lithium-ion sieve adsorbent, comprising a manganese-based ion sieve material, wherein a polyionic liquid is bonded to the manganese-based ion sieve material; wherein the polyionic liquid contains phosphate groups.

[0079] It should be noted that the ionic liquid [VEIm][DBP] interacts with Li in the brine through a specific P=O-Li coordination bond and Coulomb forces. + The process of combining these elements to achieve lithium extraction follows the following reaction procedure:

[0080] Li + +2[VEIm][DBP]+Cl - →LiCl·2[VEIm][DBP];

[0081] The adhesive provided in this embodiment of the invention is a polyionic liquid based on [VEIm][DBP]. By using the polyionic liquid as an adhesive, it also has lithium extraction performance, reducing the decline in lithium extraction performance caused by the adhesive covering the adsorption active sites of the ion sieve.

[0082] In some embodiments of the present invention, the lithium-ion sieve adsorbent is obtained by polymerizing a vinyl-modified adsorbent and an ionic liquid monomer; wherein the ionic liquid monomer contains phosphate groups and vinyl groups; the vinyl-modified adsorbent includes a manganese-based ion sieve material, on which a vinyl-containing silane coupling agent is bonded; the specific preparation process can be referred to the above description in the specification.

[0083] Furthermore, in the lithium-ion sieve adsorbent, the mass percentage of phosphate groups is 15%-35%, and the mass percentage of phosphate groups within the above range is preferable to further improve the lithium extraction effect.

[0084] This invention also provides a lithium extraction method, which uses the lithium-ion sieve adsorbent provided in this invention to adsorb lithium-containing brine. Compared with commonly used manganese-based ion sieve materials, the lithium-ion sieve adsorbent provided in this invention can further improve the adsorption capacity and reduce the manganese dissolution rate during the adsorption and regeneration process.

[0085] In some embodiments of the present invention, after adsorption is complete, the lithium-ion sieve adsorbent is washed in an inorganic acid solution to obtain delithiated lithium-ion sieve particles. During the acid washing process, on the one hand, Li... + Extracted from manganese-based lithium ion sieves; on the other hand, Li + It is extracted from LiCl·2[VEIm][DBP], while [VEIm]... + With Cl - Combined, [DBP] - With H + They combine to form dibutyl phosphate. Because dibutyl phosphate is hydrophobic, it adheres to the lithium ion sieve adsorbent particles, preventing them from entering the aqueous phase and causing water pollution. It also serves as a raw material for the regeneration of ionic liquids.

[0086] Furthermore, when washing in an inorganic acid solution, the concentration of the inorganic acid solution used should be 0.6 mol / L-1.1 mol / L, and the mass ratio of lithium ion sieve adsorbent to inorganic acid solution should be 1:(90-110). During the acid washing process, it is advisable to control the acid concentration to 0.6 mol / L-1.1 mol / L. If the acid concentration is too high, it will damage the crystal structure of the manganese-based lithium ion sieve, leading to increased manganese loss. If the acid concentration is too low, it will lead to incomplete lithium extraction from the ionic liquid, resulting in a reduction in lithium adsorption capacity.

[0087] In some embodiments of the present invention, the method further includes: mixing the delithiated lithium-ion sieve particles with a phosphoric acid organic compound and reacting them at 120°C-160°C for 5-10 hours to regenerate the delithiated lithium-ion sieve particles, after which poly(1-vinyl-3-ethylimidazolium dibutyl phosphate) [VEIm][DBP] can be obtained. The phosphoric acid organic compound used in this step is the same as that used in step S2, and the phosphoric acid organic compound is selected from at least one of tributyl phosphate and triethyl phosphate, and can be any one or more of the above.

[0088] Specifically, the reaction temperature of the delithiated lithium-ion sieve particles and the phosphoric acid organic compound can be 120℃, 130℃, 140℃, 150℃, 160℃, etc., and the reaction time can be 5h, 8h, 10h, etc.

[0089] Furthermore, the mass ratio of delithiated lithium-ion sieve particles to phosphoric acid organic compounds is 1:(0.2-0.5), that is, the solid-liquid ratio is controlled to be 1:(0.2-0.5), such as 1:0.2, 1:0.3, 1:0.4, 1:0.5, etc.

[0090] Further, after the delithiated lithium-ion sieve particles and the phosphoric acid organic compound have reacted completely, the product is washed to remove unreacted tributyl phosphate and regenerate 1-vinyl-3-ethylimidazolium dibutyl phosphate salt [VEIm][DBP]. The washing agent is not limited and can be diethyl ether.

[0091] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0092] Example 1

[0093] This embodiment provides a method for preparing a lithium-ion sieve adsorbent, the specific steps of which are as follows:

[0094] (1) Tributyl phosphate and 1-vinylimidazole in a molar ratio of 1:1 were placed in a flask and refluxed in a constant temperature oil bath at 140℃. The mixture was magnetically stirred for 15 h. The product after reaction was removed from the flask and washed with diethyl ether to remove unreacted tributyl phosphate and 1-vinylimidazole, to obtain 1-vinyl-3-ethylimidazole dibutyl phosphate salt [VEIm][DBP].

[0095] (2) Using a 90wt% methanol aqueous solution as a solvent, a 5wt% 3-methacryloylpropyltrimethoxysilane coupling agent solution was prepared. MnO2·0.5H2O material was pulverized to a particle size of 900 mesh using a high-speed pulverizer to obtain adsorbent powder. A certain amount of adsorbent powder was placed in the silane coupling agent solution and dispersed evenly. The reaction was carried out at 65℃ for 18 hours. After the reaction was completed, the mixture was filtered, and the product was washed with ethanol and dried to obtain a vinyl-modified adsorbent. The mass ratio of the adsorbent powder to the silane coupling agent was controlled to be 1:0.6.

[0096] (3) The vinyl-modified adsorbent obtained in step (2) was dispersed in N,N-dimethylformamide solvent at a solid-liquid ratio of 1 g: 2 mL. 1-Butyl-3-methylimidazolium phosphate dibutyl ester obtained in step (1) was added as the monomer, ethylene glycol dimethacrylate as the crosslinking agent, and azobisisobutyronitrile as the initiator. Nitrogen gas was introduced for 40 min to remove dissolved oxygen from the system. The reaction was then carried out under sealed conditions at 70 °C for 15 h. After the reaction was complete, the reactants were filtered out, washed three times with methanol, and dried to obtain lithium-ion sieve adsorbent particles. The mass ratio of vinyl-modified adsorbent to monomer was 10:1, the mass of the initiator was 1.2% of the monomer mass, and the mass of the crosslinking agent was 12% of the monomer mass.

[0097] This embodiment also provides a lithium extraction method, including the following steps:

[0098] (1) Lithium ion sieve adsorbent particles are placed in lithium-containing brine for lithium adsorption. After adsorption, the lithium ion sieve adsorbent particles are washed in 0.8 mol / L hydrochloric acid aqueous solution to obtain delithiated lithium ion sieve particles. The solid-liquid ratio of lithium ion sieve adsorbent particles to hydrochloric acid solution is 1:100.

[0099] The lithium-containing brine has the following composition: sodium ions (25.0 g / L), magnesium ions (32.4 g / L), lithium ions (0.6 g / L), chloride ions (311.3 g / L), and carbonate ions (15.5 g / L).

[0100] (2) The lithium-ion delithiation state lithium ion sieve particles and tributyl phosphate were mixed in a solid-liquid ratio of 1:0.35 and placed in a flask. The mixture was refluxed and condensed in a constant temperature oil bath at 140℃. The mixture was then magnetically stirred for 7 hours. The product was removed from the flask and washed with diethyl ether to remove unreacted tributyl phosphate and regenerate to obtain 1-vinyl-3-ethylimidazolium dibutyl phosphate salt [VEIm][DBP].

[0101] Example 2

[0102] This embodiment provides a method for preparing a lithium-ion sieve adsorbent, the specific steps of which are as follows:

[0103] (1) Tributyl phosphate and 1-vinylimidazole in a molar ratio of 1:1 were placed in a flask and refluxed in a constant temperature oil bath at 120°C. The mixture was magnetically stirred for 10 h. The product after reaction was removed from the flask and washed with diethyl ether to remove unreacted tributyl phosphate and 1-vinylimidazole, to obtain 1-vinyl-3-ethylimidazole dibutyl phosphate salt [VEIm][DBP].

[0104] (2) Using a 95wt% methanol aqueous solution as a solvent, a 0.5wt% 3-methacryloylpropyltrimethoxysilane coupling agent solution was prepared. MnO2·0.5H2O material was pulverized to a particle size of 800 mesh using a high-speed pulverizer to obtain adsorbent powder. A certain amount of adsorbent powder was placed in the silane coupling agent solution and dispersed evenly. The reaction was carried out at 85℃ for 12 hours. After the reaction was completed, the mixture was filtered, and the product was washed with ethanol and dried to obtain a vinyl-modified adsorbent. The mass ratio of the adsorbent powder to the silane coupling agent was controlled to be 1:0.4.

[0105] (3) The vinyl-modified adsorbent obtained in step (2) was dispersed in N,N-dimethylformamide solvent at a solid-liquid ratio of 1 g:1 mL. 1-Butyl-3-methylimidazolium phosphate dibutyl ester obtained in step (1) was added as the monomer, ethylene glycol dimethacrylate as the crosslinking agent, and azobisisobutyronitrile as the initiator. Nitrogen gas was introduced for 30 min to remove dissolved oxygen from the system. The reaction was then carried out under sealed conditions at 65°C for 24 h. After the reaction was complete, the reactants were filtered out, washed three times with methanol, and dried to obtain lithium-ion sieve adsorbent particles. The mass ratio of vinyl-modified adsorbent to monomer was 5:1, the mass of the initiator was 1% of the monomer mass, and the mass of the crosslinking agent was 10% of the monomer mass.

[0106] This embodiment also provides a lithium extraction method, including the following steps:

[0107] (1) The lithium ion sieve adsorbent particles were placed in lithium brine (with the same composition as in Example 1) for lithium adsorption. After adsorption, the lithium ion sieve adsorbent particles were washed in 0.6 mol / L hydrochloric acid. The solid-liquid ratio of the lithium ion sieve adsorbent particles to the hydrochloric acid solution was 1:100.

[0108] (2) The lithium-ion delithiation state lithium ion sieve particles and tributyl phosphate were mixed in a solid-liquid ratio of 1:0.2 and placed in a flask. The mixture was refluxed and condensed in a constant temperature oil bath at 120℃. The mixture was magnetically stirred for 10 h. The product after the reaction was removed from the flask and washed with diethyl ether to remove unreacted tributyl phosphate and regenerate to obtain 1-vinyl-3-ethylimidazolium dibutyl phosphate salt [VEIm][DBP].

[0109] Example 3

[0110] This embodiment provides a method for preparing a lithium-ion sieve adsorbent, the specific steps of which are as follows:

[0111] (1) Tributyl phosphate and 1-vinylimidazole in a molar ratio of 1:1 were placed in a flask and refluxed in a constant temperature oil bath at 160℃. The mixture was magnetically stirred for 20 h. The product after reaction was removed from the flask and washed with diethyl ether to remove unreacted tributyl phosphate and 1-vinylimidazole, to obtain 1-vinyl-3-ethylimidazole dibutyl phosphate salt [VEIm][DBP].

[0112] (2) Using a 55wt% methanol-containing aqueous solution as a solvent, a 10wt% 3-methacryloylpropyltrimethoxysilane coupling agent solution was prepared. MnO2·0.5H2O material was pulverized to a particle size of 1000 mesh using a high-speed pulverizer to obtain adsorbent powder. A certain amount of adsorbent powder was placed in the silane coupling agent solution and dispersed evenly. The reaction was carried out at 40℃ for 24 hours. After the reaction was completed, the mixture was filtered, and the product was washed with ethanol and dried to obtain a vinyl-modified adsorbent. The mass ratio of adsorbent powder to silane coupling agent was 1:0.8.

[0113] (3) The vinyl-modified adsorbent obtained in step (2) was dispersed in N,N-dimethylformamide solvent at a solid-liquid ratio of 1 g:3 mL. 1-Butyl-3-methylimidazolium phosphate dibutyl ester obtained in step (1) was added as a monomer, ethylene glycol dimethacrylate as a crosslinking agent, azobisisobutyronitrile as an initiator, and n-propanol as a pore-forming agent. Nitrogen gas was introduced for 60 min to remove dissolved oxygen from the system. The reaction was then carried out under sealed conditions at 75°C for 6 h. After the reaction was complete, the reactants were filtered out, washed three times with methanol, and dried to obtain lithium-ion sieve adsorbent particles. The mass ratio of vinyl-modified adsorbent to monomer was 15:1, the mass of the initiator was 1.5% of the monomer mass, and the mass of the crosslinking agent was 15% of the monomer mass.

[0114] This embodiment also provides a lithium extraction method, including the following steps:

[0115] (1) Lithium ion sieve adsorbent particles are placed in lithium brine for lithium adsorption. After adsorption, the lithium ion sieve adsorbent particles are washed in 1.1 mol / L hydrochloric acid. The solid-liquid ratio of lithium ion sieve adsorbent particles to hydrochloric acid solution is 1:100.

[0116] (2) The lithium-ion sieve particles in the delithiation state were mixed with tributyl phosphate at a solid-liquid ratio of 1:0.5 and placed in a flask. The mixture was refluxed and condensed in a constant temperature oil bath at 160℃. The mixture was magnetically stirred for 5 hours. The product after the reaction was removed from the flask and washed with diethyl ether to remove unreacted tributyl phosphate and regenerate to obtain 1-vinyl-3-ethylimidazolium dibutyl phosphate salt [VEIm][DBP].

[0117] Example 4

[0118] The only difference between Example 4 and Example 1 is that the concentration of hydrochloric acid used for washing during lithium extraction is 0.2 mol / L.

[0119] Example 5

[0120] The only difference between Example 5 and Example 1 is that the concentration of hydrochloric acid used for washing during lithium extraction is 1.5 mol / L.

[0121] Example 6

[0122] The only difference between Example 6 and Example 1 is that the mass ratio of vinyl-modified adsorbent to polymer monomer in step (3) is 2:1.

[0123] Example 7

[0124] The only difference between Example 7 and Example 1 is that the mass ratio of vinyl-modified adsorbent to polymer monomer in step (3) is 20:1.

[0125] Example 8

[0126] The only difference between Example 8 and Example 1 is that the mass ratio of adsorbent powder to silane coupling agent in step (2) is 1:0.1.

[0127] Example 9

[0128] The only difference between Example 9 and Example 1 is that the mass ratio of adsorbent powder to silane coupling agent in step (2) is 1:1.3.

[0129] Example 10

[0130] The only difference between Example 10 and Example 1 is that the ionic liquid monomer prepared in step (1) is 1-vinyl-3-butylimidazolium bromide [VBIm]Br.

[0131] Example 11

[0132] The only difference between Example 11 and Example 1 is that the ionic liquid monomer prepared in step (1) is 1-vinyl-3-ethylimidazolium phosphate diethyl ester salt.

[0133] Comparative Example 1

[0134] The only difference between Comparative Example 1 and Example 1 is that Comparative Example 1 directly uses manganese-based ion sieve materials for lithium extraction without granulation.

[0135] Comparative Example 2

[0136] The only difference between Comparative Example 2 and Example 1 is that step (2) is omitted and the adsorbent is not modified using a silane coupling agent.

[0137] Comparative Example 3

[0138] This comparative example provides a method for preparing a lithium-ion sieve adsorbent. The preparation method is conventional, and the specific steps are as follows: Take the adsorbent powder consistent with that in Example 1, mix it with the binder polyvinylidene fluoride (PVDF) powder and the organic solvent N,N'-dimethylacetamide (DMAC) at a mass ratio of 1:0.15:0.15, and then extrude and granulate it using a twin-screw extruder. The extruder die temperature is 230°C. After extrusion, the extruded strip is granulated using a pelletizer to obtain porous particles.

[0139] The lithium extraction method provided in this comparative example is the same as that in Example 1.

[0140] Experimental Example 1

[0141] Infrared spectroscopy tests were performed on the adsorbent particles prepared in Example 1 before and after lithium adsorption. Figure 2 As shown.

[0142] Depend on Figure 2 It can be seen that the infrared spectrum of the adsorbent is at 600 cm⁻¹ -1 The basic characteristic peaks of Mn-O bonds appear on both sides, at 1243 cm⁻¹. -1 The peak at the position is the stretching vibration peak of -P=O. This stretching vibration peak can be seen in the infrared spectrum after lithium adsorption by the adsorbent, starting from 1243 cm⁻¹. -1 The wavenumber shifted down to 1229 cm⁻¹, and the decrease was due to the O atom in the —P=O bond reacting with the Li atom. + The coordination formation of —P=O—Li weakens the bond energy of the —P=O bond and reduces the stretching vibration frequency. Furthermore, the peak intensity of the —P=O bond decreases after lithium adsorption, which may be related to the reduced electron cloud density of O on the —P=O bond, further illustrating the influence of Li. + It can gain electrons from the O at the -P=O junction. Therefore, in the lithium extraction process using this adsorbent particles, Li... + In addition to combining with manganese-based ion sieves through ion exchange reactions, it can also gain electrons from the O of the —P=O—Li in poly[VEIm][DBP] ion liquid. The —P=O—Li coordination bond formed based on this electron donation and acceptance increases the number of lithium adsorption sites after the manganese-based lithium ion sieve is granulated, thereby improving the lithium adsorption capacity of the manganese-based lithium ion sieve after molding.

[0143] Experimental Example 2

[0144] The adsorbents prepared in the examples and comparative examples were subjected to adsorption capacity tests and manganese dissolution tests. The test results are shown in Table 1.

[0145] Test method:

[0146] (1) Adsorption capacity test: Lithium-ion sieve adsorbent particles were immersed in a lithium-containing solution (0.05 mol / L, S / L = 1:1000) and shaken at 100 rpm in a constant temperature shaking chamber at 25℃ for 24 h to ensure adsorption equilibrium. The Li+ content in the solution was determined using ICP-OES. The adsorption capacity Q (mg / g) was calculated using the following formula: Q = (C0 - C t )V / m, where C0 (mg / L) is Li + The initial concentration of lithium ions is Ct (mg / L), which is the concentration of lithium ions when adsorption equilibrium is reached; V (L) is the volume of the solution; and m (g) is the mass of the lithium ion sieve.

[0147] (2) Manganese dissolution test: The lithium ion sieve adsorbent particles were acid-washed with HCl at a solid-liquid ratio of 1:100 at room temperature for 24 hours. The supernatant was then partially removed using a pipette, and the concentration of metal cations in the solution was measured using ICP-OES. The manganese dissolution rate (DE) was then calculated. Mn The calculation formula is as follows: DE Mn = (C1×V1) / m, where C1 (mg / L) is the detection concentration of manganese ions, V1 (L) is the solution volume, and m (g) is the mass of the adsorbent powder.

[0148] Table 1. Adsorption capacity and manganese dissolution test results of the adsorbents prepared in the examples and comparative examples.

[0149]

[0150]

[0151] As can be seen from Table 1, the manganese-based adsorbent prepared in the embodiments of the present invention can significantly improve the lithium adsorption capacity after being polymerized and granulated with ionic liquid, while reducing the manganese dissolution rate and increasing the cycle life of the adsorbent.

[0152] As can be seen from Examples 1, 4 and 5, during the acid elution process, excessive acid concentration will damage the crystal structure of the manganese-based ion sieve, leading to increased manganese loss, while insufficient acid concentration will result in incomplete lithium removal from the ionic liquid, leading to a reduction in lithium adsorption capacity.

[0153] Industrial applicability

[0154] This invention involves forming a polyionic liquid with phosphate groups on a manganese-based ion sieve material. The polyionic liquid can not only act as a binder but also play a role in lithium extraction. The modification process is convenient to operate, and the reaction conditions are mild and controllable, making it highly practical for industrial applications.

Claims

1. A lithium-ion sieve adsorbent, characterized in that, Includes manganese-based ion sieve materials, on which polyionic liquids are bonded; The anions in the polyionic liquid contain P=O groups; The lithium-ion sieve adsorbent is obtained by polymerizing a vinyl-modified adsorbent and an ionic liquid monomer; wherein the ionic liquid monomer contains phosphate groups and vinyl groups; the vinyl-modified adsorbent includes a manganese-based ion sieve material, on which a vinyl-containing silane coupling agent is bonded.

2. The lithium-ion sieve adsorbent according to claim 1, characterized in that, The ionic liquid monomer is selected from at least one of 1-vinyl-3-ethylimidazolium dibutyl phosphate and 1-vinyl-3-ethylimidazolium diethyl phosphate.

3. The lithium-ion sieve adsorbent according to claim 1, characterized in that, The manganese-based ion sieve material is selected from at least one of MnO2·0.5H2O, λ-MnO2, and MnO2·0.3H2O.

4. The lithium-ion sieve adsorbent according to claim 1, characterized in that, In the lithium-ion sieve adsorbent, the mass percentage of phosphate groups is 15%-35%.

5. The lithium-ion sieve adsorbent according to claim 1, characterized in that, The silane coupling agent is selected from at least one of vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, ethylenetriisopropenyloxysilane, methylvinyldimethoxysilane, methylvinyldiethoxysilane, and tetramethyldivinyldisiloxane.

6. A method for preparing the lithium-ion sieve adsorbent according to any one of claims 1-5, characterized in that, include: A vinyl-modified adsorbent is mixed and reacted with an ionic liquid monomer containing phosphate groups and vinyl groups to polymerize the ionic liquid monomer. The vinyl-modified adsorbent includes a manganese-based ion sieve material, on which a vinyl-containing silane coupling agent is bonded.

7. The preparation method according to claim 6, characterized in that, include: The manganese-based ion sieve material is modified with a vinyl-containing silane coupling agent to obtain a vinyl-modified adsorbent, and the vinyl-modified adsorbent is mixed and reacted with the ionic liquid monomer.

8. The preparation method according to claim 7, characterized in that, The preparation process of the vinyl-modified adsorbent includes: mixing the manganese-based ion sieve material, the silane coupling agent and the solvent, and reacting them at 40℃-85℃ for 12h-24h.

9. The preparation method according to claim 8, characterized in that, A silane coupling agent and a solvent are mixed to obtain a silane coupling agent solution. The manganese-based ion sieve material is then mixed with the silane coupling agent solution, and the concentration of the silane coupling agent solution is 0.5wt%-10wt%.

10. The preparation method according to claim 8, characterized in that, The mass ratio of the manganese-based ion sieve material to the silane coupling agent is 1:(0.4-0.8).

11. The preparation method according to claim 8, characterized in that, The particle size of the manganese-based ion sieve material is 800-1000 mesh.

12. The preparation method according to claim 8, characterized in that, The solvent is a mixture of an organic solvent and water, wherein the mass fraction of water in the mixture is 5%-15%.

13. The preparation method according to claim 12, characterized in that, The organic solvent is selected from at least one of methanol, ethanol, isopropanol, dimethyl sulfoxide, and N-methylpyrrolidone.

14. The preparation method according to claim 8, characterized in that, After the reaction between the manganese-based ion sieve material and the silane coupling agent is completed, solid-liquid separation is performed to obtain a solid material. The solid material is then washed and dried to obtain the vinyl-modified adsorbent.

15. The preparation method according to claim 7, characterized in that, The vinyl-modified adsorbent, solvent, ionic liquid monomer, crosslinking agent, and initiator are mixed and polymerized at 65℃-75℃ for 6h-24h.

16. The preparation method according to claim 15, characterized in that, The mass ratio of the vinyl-modified adsorbent to the ionic liquid monomer is (5-15):

1.

17. The preparation method according to claim 15, characterized in that, The crosslinking agent is selected from at least one of ethylene glycol dimethacrylate and divinylbenzene; the mass ratio of the crosslinking agent to the ionic liquid monomer is (10-15):

100.

18. The preparation method according to claim 15, characterized in that, The initiator is selected from at least one of azobisisobutyronitrile and benzoyl peroxide; the mass ratio of the initiator to the ionic liquid monomer is (1.0-1.5):

100.

19. The preparation method according to claim 15, characterized in that, First, the vinyl-modified adsorbent and the solvent are mixed, then the ionic liquid monomer, the crosslinking agent and the initiator are mixed, and an inert gas is introduced for 30-60 minutes. After that, the polymerization reaction is carried out under closed conditions.

20. The preparation method according to claim 19, characterized in that, The solvent is selected from at least one of N,N-dimethylformamide and N-methylpyrrolidone; the amount of solvent used per gram of the vinyl-modified adsorbent is 1 mL to 3 mL.

21. The preparation method according to claim 19, characterized in that, After the polymerization reaction is completed, solid-liquid separation is performed to obtain solid material, which is then washed and dried.

22. The preparation method according to claim 6, characterized in that, The preparation process of the ionic liquid monomer includes: reacting a phosphoric acid organic compound with a vinyl compound; The phosphate-based organic compound is selected from at least one of tributyl phosphate and triethyl phosphate; The vinyl compound is selected from at least one of 1-vinylimidazolium and 2-dimethylaminoethyl methacrylate.

23. The preparation method according to claim 22, characterized in that, The reaction temperature between the phosphate organic compound and the vinyl compound is 120℃-160℃, and the reaction time is 10h-20h.

24. The preparation method according to claim 22, characterized in that, The molar ratio of the phosphate organic compound to the vinyl compound is 1:(0.9-1.1).

25. The preparation method according to claim 22, characterized in that, After the reaction between the phosphoric acid organic compound and the vinyl compound is complete, extraction and washing are performed; wherein the extractant used in the extraction process is selected from at least one of diethyl ether and ethyl acetate.

26. A method for lithium extraction, characterized in that, The lithium-ion sieve adsorbent prepared by any one of the lithium-ion sieve adsorbents according to claims 1-5 or any one of the preparation methods according to claims 6-25 is used to adsorb lithium-containing brine.

27. The lithium extraction method according to claim 26, characterized in that, After adsorption is complete, the lithium-ion sieve adsorbent is washed in an inorganic acid solution to obtain delithiated lithium-ion sieve particles.

28. The lithium extraction method according to claim 27, characterized in that, The concentration of the inorganic acid solution is 0.6 mol / L-1.1 mol / L, and the mass ratio of the lithium ion sieve adsorbent to the inorganic acid solution is 1:(90-110).

29. The lithium extraction method according to claim 27, characterized in that, Also includes: The delithiated lithium-ion sieve particles and phosphate-based organic compounds are mixed and reacted at 120℃-160℃ for 5-10 hours.

30. The lithium extraction method according to claim 29, characterized in that, The phosphate-based organic compound is selected from at least one of tributyl phosphate and triethyl phosphate.

31. The lithium extraction method according to claim 29, characterized in that, The mass ratio of the delithiated lithium-ion sieve particles to the phosphoric acid organic compound is 1:(0.2-0.5).

32. The lithium extraction method according to claim 29, characterized in that, After the delithiated lithium-ion sieve particles and the phosphoric acid organic compound have reacted completely, the product is washed.

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