Lithium adsorbent, method of preparation and use

Abstract

The application discloses a lithium adsorbent, a preparation method and application, wherein the lithium adsorbent comprises lithium ion sieves and a first coating layer, and the first coating layer comprises a polymer containing -NH-COO- and S-S groups. The application has repeating reaction nodes -NH-COO- in the polymer chain of the adsorbent, can form a rich hydrogen bond network, and has dynamic disulfide bonds and hydrogen bonds in the first coating layer. The rearrangement of the dynamic disulfide bonds and the hydrogen bonds can simultaneously repair defects on the first coating layer in the coating process, improve the strength of the first coating layer, reduce damage and peeling of the first coating layer in the lithium extraction process, and the existence of the first coating layer can reduce the loss of the lithium ion sieves in the lithium extraction process.

Description

Technical Field

[0001] This invention relates to the field of lithium extraction technology, and more specifically, to lithium adsorbents, preparation methods, and applications. Background Technology

[0002] Lithium, the lightest metallic element in nature, has a wide range of applications. In nature, lithium is mainly found in spodumene, lepidolite, and brine. Currently, there are two main lithium extraction technologies: the calcination method using lithium ore as raw material and the adsorption method extracting lithium resources from brine. While ore-based lithium extraction is a mature technology, it is costly. In contrast, brine-based lithium extraction does not require a calcination process, resulting in relatively lower costs and attracting widespread attention from researchers.

[0003] Currently, there are two main methods for extracting lithium from salt lake brine: one is adsorption, which currently mostly uses aluminum-based adsorbents. However, aluminum-based adsorbents have low adsorption capacity (1-3 mg / g), resulting in low lithium ion concentration in the eluent (30-80 mg / L), high washing and concentration costs, and thus poor economic efficiency. The second method is membrane separation or nanofiltration, but this method suffers from drawbacks such as short membrane lifespan and low lithium ion concentration (50-100 mg / L), making it unsuitable for long-term use and inefficient. Considering the characteristics of salt lake brine in my country, adsorption is the optimal solution. Manganese-based ion sieve adsorbents have a large adsorption capacity (15-40 mg / g) and have attracted much attention from researchers. However, manganese dissolution during adsorption leads to adsorbent loss. This problem can be addressed by coating. However, current technology struggles to achieve a tight bond between the coating layer and the core, making it prone to detachment and damage during lithium extraction, thus affecting adsorbent performance. Summary of the Invention

[0004] The purpose of this invention is to provide a lithium adsorbent, a preparation method, and an application. The coating layer in the lithium adsorbent is tightly bonded to the core, and the coating layer is not easily damaged or detached during the lithium extraction process.

[0005] This invention is implemented as follows:

[0006] In a first aspect, the present invention provides a lithium adsorbent comprising a lithium ion sieve and a first coating layer, wherein the first coating layer comprises a polymer containing -NH-COO- and SS groups.

[0007] In some embodiments, the lithium-ion screen is a manganese-based lithium-ion screen;

[0008] And / or, in the lithium adsorbent, the mass fraction of polymers containing -NH-COO- and SS groups is 1% to 5%;

[0009] And / or, the first coating layer contains primary lithium-ion sieve particles, the primary lithium-ion sieve particles comprising a lithium-ion sieve and a first polymer coated on the lithium-ion sieve, the first polymer having -NH-COO- groups;

[0010] And / or, the mass ratio of lithium ion screen to first polymer in the primary particles of the lithium ion screen is (2-5):1;

[0011] And / or, the polymer containing -NH-COO- and SS groups is an amorphous polymer.

[0012] In a second aspect, the present invention provides a method for preparing a lithium adsorbent, comprising: coating the surface of the lithium ion sieve with a polymer containing -NH-COO- and SS groups to obtain a lithium adsorbent.

[0013] In some implementations, the following are included:

[0014] A single polymerization process is performed to coat the lithium-ion sieve once, resulting in lithium-ion sieve primary particles coated with a first polymer, wherein the first polymer has -NH-COO- groups.

[0015] Secondary polymerization involves reacting the primary lithium-ion sieve particles with a second polymer containing SS bonds to obtain the lithium adsorbent.

[0016] In some embodiments, the first polymer is end-capped with -NCO, and the second polymer is end-capped with -NH2 or -OH.

[0017] In some embodiments, in the primary polymerization step, the lithium ion sieve, the -OH-containing polymer, and the first -NCO-containing compound are mixed to obtain a first mixture, which is then subjected to a primary polymerization reaction and granulation to obtain the primary lithium ion sieve particles;

[0018] Preferably, the -OH-containing polymer is one or more selected from polybutanediol, polytetrahydrofuran ether, polyethylene glycol, and polypentylene glycol;

[0019] Preferably, the first -NCO-containing compound is one or more of hexamethylene diisocyanate, toluene diisocyanate, methyl isocyanate, n-butyl isocyanate, tert-butyl isocyanate, phenyl isocyanate, p-chlorophenyl isocyanate, 3-chlorophenyl isocyanate, 3,4-dichlorophenyl isocyanate, p-methylphenyl isocyanate, isophorone diisocyanate, and phenylmethane triisocyanate.

[0020] In some implementations, the primary aggregation step satisfies at least one of the following:

[0021] a. The molar ratio of -OH to -NCO in the first mixture is 1:(2-3);

[0022] b. The mass ratio of the lithium-ion sieve to the total amount of the -OH-containing polymer and the first -NCO-containing compound is (10-15):1;

[0023] c. The first mixture further includes a first solvent, wherein the total concentration of the lithium ion sieve, the -OH-containing polymer, and the first -NCO-containing compound in the first mixture is 1 g / ml to 5 g / ml;

[0024] d. The first mixture further includes a first solvent, which is one or more of dichloromethane, diethyl ether, toluene, and ethyl acetate;

[0025] e. The first mixture also includes a first catalyst, wherein the amount of the first catalyst added is 1% to 3% of the mass of the first -NCO compound;

[0026] f. The first mixture further includes a first catalyst, which is one or more of dibutyltin diacid, palladium metal catalyst, and nickel metal catalyst;

[0027] g. The temperature of the primary polymerization reaction is 50℃~70℃, and the reaction time is 3h~5h;

[0028] h. After the granulation step, drying is carried out at a temperature of 60℃~80℃ for a time of 20h~50h.

[0029] In some implementations, the secondary polymerization step satisfies at least one of the following AG:

[0030] A. The reaction temperature of the secondary polymerization step is 60℃~80℃, and the reaction time is 5h~10h;

[0031] B. After the secondary polymerization reaction is completed, the reaction liquid is filtered and dried to separate the lithium adsorbent;

[0032] C. The mass of the second polymer is 1% to 5% of the mass of the primary particles from the lithium-ion sieve;

[0033] D. The reaction solution also includes a second solvent, and the content of primary lithium-ion sieve particles in the pre-reaction solution of the secondary polymerization reaction is 1 g / ml to 5 g / ml;

[0034] E. The reaction solution also includes a second solvent, which is one or more of dichloromethane, diethyl ether, toluene, and ethyl acetate;

[0035] F. The reaction solution also includes a second catalyst, the amount of which is 1% to 3% of the mass of the second polymer;

[0036] G. The reaction solution also includes a second catalyst, which is one or more of dibutyltin diacid, palladium metal catalyst and nickel metal catalyst.

[0037] In some embodiments, the preparation of the second polymer is also included: a third polymerization reaction is carried out between an SS-containing compound and a second -NCO-containing compound to obtain the second polymer, wherein the SS-containing compound further has -NH2 or -OH.

[0038] Preferably, the reaction temperature of the third polymerization reaction is 30℃~50℃, and the reaction time is 10h~20h;

[0039] Preferably, the molar ratio of the SS-containing compound to the second -NCO-containing compound is (1.1-1.2):1;

[0040] Preferably, the SS-containing compound is one or more selected from cystamine, 4,4"-diaminodiphenyl disulfide, 2-hydroxyethyl disulfide, bis(2-hydroxyethyl) disulfide, 3,3-dihydroxydiphenyl disulfide, 4,4-dihydroxydiphenyl disulfide and 2,2-diaminodiphenyl disulfide.

[0041] Preferably, the second -NCO-containing compound is one or more selected from hexamethylene diisocyanate, toluene diisocyanate, methyl isocyanate, n-butyl isocyanate, tert-butyl isocyanate, phenyl isocyanate, p-chlorophenyl isocyanate, 3-chlorophenyl isocyanate, 3,4-dichlorophenyl isocyanate, p-methylphenyl isocyanate, isophorone diisocyanate, and phenylmethane triisocyanate.

[0042] Preferably, the reaction solution of the third polymerization reaction further includes a third solvent, which is one or more of dimethyl sulfoxide, N,N-dimethylformamide, dichloromethane, tetrahydrofuran, and N-methylpyrrolidone; more preferably, the third polymerization reaction includes: adding solution A dropwise to solution B while stirring, and after the addition is complete, reacting at 30℃~50℃ for 10h~20h, then drying by rotary evaporation to separate the second polymer, wherein solution A is a mixture containing an SS compound and a third solvent, and solution B is a mixture containing a second -NCO compound and a third solvent; more preferably, the concentration of the solute in solution A and / or solution B is 1g / ml~5g / ml.

[0043] Thirdly, the present invention provides the application of the lithium adsorbent described in the foregoing embodiments or the lithium adsorbent prepared by the method described in any one of the foregoing embodiments in selective lithium extraction.

[0044] The present invention has the following beneficial effects:

[0045] The polymer chain in the adsorbent of this invention has repeating reaction nodes -NH-COO-, which can form a rich hydrogen bond network. The first coating layer contains dynamic disulfide bonds and hydrogen bond rearrangements. By utilizing the self-repairing effect of these rearrangements, defects on the first coating layer can be repaired simultaneously during the coating process, thereby improving the strength of the first coating layer and reducing damage and detachment of the first coating layer during lithium extraction. The presence of the first coating layer can reduce the loss during lithium ion sieve lithium extraction. Attached Figure Description

[0046] 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.

[0047] Figure 1 This is a schematic diagram of the mechanism of lithium adsorbent remediation in this invention;

[0048] Figure 2 The preparation process of the first coating layer in the lithium adsorbent in Example 1;

[0049] Figure 3 The infrared spectrum of the lithium adsorbent in Example 1;

[0050] Figure 4 The image shows the XRD pattern of the lithium adsorbent in Example 1. Detailed Implementation

[0051] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0052] The present invention provides a lithium adsorbent, comprising a lithium ion sieve and a first coating layer, wherein the first coating layer comprises a polymer containing -NH-COO- and SS groups.

[0053] The polymer chain in the adsorbent of this invention has repeating reaction nodes -NH-COO-, which can form a rich hydrogen bond network. The first coating layer contains dynamic disulfide bond and hydrogen bond rearrangements. Utilizing the self-healing effect of these rearrangements, defects in the first coating layer can be simultaneously repaired during the coating process, improving the strength of the first coating layer and reducing damage and detachment during lithium extraction. The mechanism is as follows: Figure 1 As shown, the presence of the first coating layer can reduce the loss during the lithium ion screening and extraction process.

[0054] In some embodiments, the lithium-ion sieve is a manganese-based lithium-ion sieve, which has a large adsorption capacity.

[0055] In some embodiments, the first coating layer contains primary lithium-ion sieve particles coated with a first polymer, the first polymer having -NH-COO- groups. The first polymer encapsulates the lithium-ion sieve, providing initial protection. Furthermore, compared to directly coating the lithium-ion sieve surface with a polymer containing -NH-COO- and SS groups, the presence of the first polymer allows for dynamic rearrangement of disulfide and hydrogen bonds between the first coating layer and the core of the primary lithium-ion sieve particles. This rearrangement, with its self-healing effect, simultaneously repairs defects at the interface between the first coating layer and the core during the coating process, enhancing the bond between them. This rearrangement results in a tighter coating, further reducing damage and detachment of the first coating layer during lithium extraction. Additionally, the presence of the first coating layer reduces losses during lithium extraction from the lithium-ion sieve.

[0056] In some embodiments, the mass fraction of the polymer containing -NH-COO- and SS groups in the lithium adsorbent is 1% to 5%, specifically, it can be any value between 1%, 2%, 3%, 4%, 5%, or 1% to 5%. If the content of the coated polymer is too small, it cannot effectively reduce the loss of lithium ions; if the content of the coated polymer is too large, it will also reduce the adsorption capacity.

[0057] In some embodiments, the mass ratio of lithium ion screen to first polymer in the primary particles of the lithium ion screen is (2-5):1, specifically any value between 2:1, 3:1, 4:1, 5:1 or (2-5):1. If the content of the first polymer is too low, it cannot effectively encapsulate the lithium ion screen.

[0058] In some embodiments, the polymer containing -NH-COO- and SS groups is an amorphous polymer. The local movement of the molecular chains of the amorphous polymer is conducive to the rapid transport of lithium ions, and therefore does not affect the insertion and extraction of lithium ions during the lithium extraction process.

[0059] Secondly, the present invention provides a method for preparing the lithium adsorbent described in the foregoing embodiments, comprising: coating the surface of the lithium ion sieve with a polymer containing -NH-COO- and SS groups to obtain the lithium adsorbent.

[0060] In some implementations, the following are included:

[0061] A single polymerization process is performed to coat the lithium-ion sieve once, resulting in lithium-ion sieve primary particles coated with a first polymer, wherein the first polymer has -NH-COO- groups.

[0062] Secondary polymerization involves reacting the primary lithium-ion sieve particles with a second polymer containing SS bonds to obtain the lithium adsorbent.

[0063] like Figure 2 As shown, two polymerization reactions are carried out. The primary lithium-ion screen particles obtained by the first polymerization reaction are particles obtained by embedding multiple lithium-ion screen particles in the first polymer. The second polymerization forms a first coating layer on the surface of the primary lithium-ion screen particles, which plays a protective role for the primary lithium-ion screen particles and can reduce the wear of the lithium-ion screen.

[0064] In some embodiments, the first polymer is end-capped with -NCO, and the second polymer is end-capped with -NH2 or -OH. The connection between the first polymer and the second polymer is achieved by the reaction of -NCO in the first polymer with -NH2 or -OH in the second polymer.

[0065] In some embodiments, in the primary polymerization step, the lithium ion sieve, the -OH-containing polymer, and the first -NCO-containing compound are mixed to obtain a first mixture, and then subjected to a primary polymerization reaction and granulation to obtain the primary lithium ion sieve particles. Typically, granulation is performed by basic granulation.

[0066] Preferably, the -OH-containing polymer is one or more of polybutanediol, polytetrahydrofuran ether, polyethylene glycol, and polypentylene glycol, providing the -OH required for the reaction;

[0067] Preferably, the first -NCO-containing compound is one or more of hexamethylene diisocyanate, toluene diisocyanate, methyl isocyanate, n-butyl isocyanate, tert-butyl isocyanate, phenyl isocyanate, p-chlorophenyl isocyanate, 3-chlorophenyl isocyanate, 3,4-dichlorophenyl isocyanate, p-methylphenyl isocyanate, isophorone diisocyanate, and phenylmethane triisocyanate, providing the -NCO required for the reaction.

[0068] In some implementations, the primary aggregation step satisfies at least one of the following:

[0069] a. The molar ratio of -OH to -NCO in the first mixture is 1:(2-3), specifically any value between 1:2, 1:2.2, 1:2.4, 1:2.6, 1:2.8, 1:3 or 1:(2-3), wherein -NCO is in excess and can subsequently react with the second polymer.

[0070] b. The mass ratio of the lithium ion sieve to the total amount of the -OH-containing polymer and the first -NCO-containing compound is (10-15):1, specifically, it can be any value between 10:1, 11:1, 12:1, 13:1, 14:1, 15:1 or (10-15):1. If the content of the coated polymer is too small, the loss of the lithium ion sieve cannot be effectively reduced. If the content of the coated polymer is too large, the adsorption capacity will also be reduced.

[0071] c. The first mixture further includes a first solvent, wherein the total concentration of the lithium ion sieve, the -OH-containing polymer and the first -NCO-containing compound in the first mixture is 1 g / ml to 5 g / ml, specifically it can be any value between 1 g / ml, 2 g / ml, 3 g / ml, 4 g / ml, 5 g / ml or 1 g / ml to 5 g / ml, and the liquid phase environment is conducive to improving reaction efficiency and the full reaction of reactants;

[0072] d. The first mixture also includes a first solvent, which is one or more of dichloromethane, diethyl ether, toluene, and ethyl acetate, and has a low boiling point, making it easy to remove;

[0073] e. The first mixture also includes a first catalyst, the amount of which is 1% to 3% of the mass of the first -NCO compound, specifically any value between 1%, 1.5%, 2%, 2.5%, 3% or 1% to 3%, which is beneficial to the forward reaction and improves the reaction efficiency;

[0074] f. The first mixture further includes a first catalyst, which is one or more of dibutyltin diacid, palladium metal catalyst, and nickel metal catalyst;

[0075] g. The temperature of the primary polymerization reaction is 50℃~70℃, specifically 50℃, 55℃, 60℃, 65℃, 70℃ or any value between 50℃ and 70℃, and the reaction time is 3h~5h, specifically 3h, 3.5h, 4h, 4.5h, 5h or any value between 3h and 5h, so that the reactants can react completely;

[0076] h. After the granulation step, drying is performed at a temperature of 60℃~80℃, specifically any value between 60℃, 65℃, 70℃, 75℃, 80℃ or 60℃~80℃, for a drying time of 20h~50h, specifically any value between 20h, 30h, 40h, 50h or 20h~50h, to remove the solvent.

[0077] In some implementations, the secondary polymerization step satisfies at least one of the following AG:

[0078] A. The reaction temperature of the secondary polymerization step is 60℃~80℃, specifically any value between 60℃, 65℃, 70℃, 75℃, 80℃ or 60℃~80℃, and the reaction time is 5h~10h, specifically any value between 5h, 6h, 7h, 8h, 9h, 10h or 5h~10h, to ensure that the reactants react completely;

[0079] B. After the secondary polymerization reaction is completed, the reaction liquid is filtered and dried to remove the solvent and separate the lithium adsorbent;

[0080] C. The mass of the second polymer is 1% to 5% of the mass of the primary particles of the lithium ion sieve. Specifically, it can be any value between 1%, 2%, 3%, 4%, 5%, or 1% to 5%. If the SS content in the first coating layer is too low, it cannot effectively reduce the loss of the lithium ion sieve. If the SS content in the first coating layer is too high, the total content of the polymer will also increase, thereby reducing the adsorption capacity.

[0081] D. The reaction solution also includes a second solvent. The content of primary lithium-ion sieve particles in the pre-reaction solution of the secondary polymerization reaction is 1g / ml to 5g / ml. Specifically, it can be any value between 1g / ml, 2g / ml, 3g / ml, 4g / ml, 5g / ml or 1g / ml to 5g / ml. The liquid phase environment is conducive to improving reaction efficiency and the full reaction of reactants.

[0082] E. The reaction solution also includes a second solvent, which is one or more of dichloromethane, diethyl ether, toluene, and ethyl acetate, and has a low boiling point, making it easy to remove;

[0083] F. The reaction solution also includes a second catalyst, the amount of which is 1% to 3% of the mass of the second polymer, specifically any value between 1%, 1.5%, 2%, 2.5%, 3%, or 1% to 3%, which is beneficial to the forward reaction and improves the reaction efficiency;

[0084] G. The reaction solution also includes a second catalyst, which is one or more of dibutyltin diacid, palladium metal catalyst and nickel metal catalyst.

[0085] In some embodiments, the preparation of the second polymer is further included: a third polymerization reaction is carried out between an SS-containing compound and a second -NCO-containing compound to obtain the second polymer, wherein the SS-containing compound also has -NH2 or -OH; and an SS-terminated polymer with -NH2 or -OH ends is obtained for reaction with the first polymer in the primary particles of the lithium ion sieve.

[0086] Preferably, the reaction temperature of the third polymerization reaction is 30℃~50℃, specifically it can be any value between 30℃, 35℃, 40℃, 45℃, 50℃ or 30℃~50℃, and the reaction time is 10h~20h, specifically it can be any value between 10h, 12h, 14h, 16h, 18h, 20h or 10h~20h, so that the reactants can react completely;

[0087] Preferably, the molar ratio of the SS-containing compound to the second -NCO-containing compound is (1.1 to 1.2):1, specifically it can be any value between 1.1:1, 1.12:1, 1.14:1, 1.16:1, 1.18:1, 1.2:1 or (1.1 to 1.2):1;

[0088] Preferably, the SS-containing compound is one or more of cystamine, 4,4"-diaminodiphenyl disulfide, 2-hydroxyethyl disulfide, bis(2-hydroxyethyl) disulfide, 3,3-dihydroxydiphenyl disulfide, 4,4-dihydroxydiphenyl disulfide, and 2,2-diaminodiphenyl disulfide, providing SS and -NH2 or -OH;

[0089] Preferably, the second -NCO-containing compound is one or more of hexamethylene diisocyanate, toluene diisocyanate, methyl isocyanate, n-butyl isocyanate, tert-butyl isocyanate, phenyl isocyanate, p-chlorophenyl isocyanate, 3-chlorophenyl isocyanate, 3,4-dichlorophenyl isocyanate, p-methylphenyl isocyanate, isophorone diisocyanate, and phenylmethane triisocyanate, providing -NCO;

[0090] Preferably, the reaction solution of the third polymerization reaction further includes a third solvent, which is one or more of dimethyl sulfoxide, N,N-dimethylformamide, dichloromethane, tetrahydrofuran, and N-methylpyrrolidone; more preferably, the third polymerization reaction includes: adding solution A dropwise to solution B and stirring to control the uniformity of the reaction; after the addition is complete, reacting at 30℃~50℃ for 10h~20h, followed by rotary evaporation and drying to separate the second polymer, specifically at temperatures of 30℃, 35℃, 40℃, 45℃, 50℃ or 30℃~50℃. The reaction time can be any value between 0°C and 10h, 12h, 14h, 16h, 18h, 20h or any value between 10h and 20h; wherein solution A is a mixture containing an SS compound and a third solvent, and solution B is a mixture containing a second -NCO compound and a third solvent. More preferably, the concentration of solute in solution A and / or solution B is 1g / ml to 5g / ml, specifically 1g / ml, 2g / ml, 3g / ml, 4g / ml, 5g / ml or any value between 1g / ml and 5g / ml.

[0091] Thirdly, the present invention provides the application of the lithium adsorbent described in the foregoing embodiments or the lithium adsorbent prepared by the method described in any one of the foregoing embodiments in selective lithium extraction.

[0092] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0093] Example 1:

[0094] This embodiment provides a method for preparing a lithium adsorbent, including the following steps:

[0095] S1: Lithium-ion sieve primary polymerization granulation

[0096] Lithium manganese oxide lithium ion sieve, polybutane glycol, hexamethylene diisocyanate, and dibutyltin diacid were mixed and added to dichloromethane. The mixture was stirred and reacted in a nitrogen glove box at 60°C for 3 hours. Subsequently, the mixture was granulated by extrusion and dried at 70°C for 24 hours to obtain primary lithium ion sieve particles.

[0097] The raw material addition ratio is: -OH, -NCO group ratio 1:2.5; the total concentration of lithium manganese oxide lithium ion sieve, polybutane glycol, and hexamethylene diisocyanate in the dichloromethane solution is 1.5 g / ml; the mass ratio of lithium ion sieve to polybutane glycol and hexamethylene diisocyanate is 12:1; and the amount of dibutyltin diacid added is 2% of the mass of hexamethylene diisocyanate.

[0098] S2: Preparation of polymers containing SS bonds

[0099] Cystamine was dissolved in N-methylpyrrolidone to obtain solution 1, and hexamethylene diisocyanate was dissolved in N-methylpyrrolidone to obtain solution 2. Solution 1 was slowly added dropwise to solution 2 while stirring continuously. After the addition was complete, the reaction was carried out at 40°C for 15 hours. The concentration of solution 1 and solution 2 was prepared to be 2 g / ml. After the reaction was completed, the polymer containing SS bonds was obtained by rotary evaporation and drying.

[0100] The molar ratio of cystamine to hexamethylene diisocyanate is 1.1:1;

[0101] S3: Lithium-ion sieve secondary polymerization coating

[0102] The primary lithium-ion sieve particles, dichloromethane, the polymer containing SS bonds synthesized in step S2, and dibutyltin diacid were mixed. The amount of dibutyltin diacid added was 2% of the mass of the polymer containing SS bonds, and the mass ratio of the primary lithium-ion sieve particles to the polymer containing SS bonds was 1:3%. The concentration of the primary lithium-ion sieve particles in the solution before the reaction was 1.5 g / ml. The reaction was stirred at 70℃ for 8 h, followed by filtration and drying to obtain the lithium-ion sieve adsorbent. The infrared and XRD results of the lithium-ion sieve adsorbent are shown in the figure. Figure 3and Figure 4 This indicates that the lithium adsorbent obtained in this embodiment contains -NH-COO- and SS, and the polymer is amorphous.

[0103] Example 2:

[0104] This embodiment provides a method for preparing a lithium adsorbent, including the following steps:

[0105] Lithium manganese oxide lithium ion sieve, polybutane glycol, hexamethylene diisocyanate, cystamine, and dibutyltin diacid were mixed and added to dichloromethane. The mixture was stirred and reacted in a nitrogen glove box at 60°C for 3 hours. Subsequently, the mixture was granulated by extrusion and dried at 70°C for 24 hours to obtain primary lithium ion sieve particles.

[0106] The ratio of raw materials added is: -OH, -SS-, -NCO groups in the ratio of 1:1:2.5, and the ratio of the mass of the reaction raw materials to the volume of the solvent dichloromethane is 1.5 g / ml.

[0107] The mass ratio of lithium ion sieve to hexamethylene diisocyanate, cystamine and polybutanediol is 12:1.

[0108] The amount of dibutyltin dicarboxylate added is 2% of the mass of hexamethylene diisocyanate.

[0109] Example 3:

[0110] This embodiment provides a method for preparing a lithium adsorbent, including the following steps:

[0111] S1: Same as S2 in Example 1;

[0112] S2: The only difference from S3 in Example 1 is that the lithium ion screen particles are replaced with lithium manganese oxide lithium ion screens of equal mass.

[0113] Example 4

[0114] This embodiment provides a method for preparing a lithium adsorbent, including the following steps:

[0115] S1: Same as S1 in Example 1;

[0116] S2: The only difference from S3 in Example 1 is that the polymer containing SS bonds synthesized in step S2 is replaced with an equal amount of cystamine as in step S2 of Example 1.

[0117] Example 5

[0118] This embodiment provides a method for preparing a lithium adsorbent, including the following steps:

[0119] S1: Lithium-ion sieve primary polymerization granulation

[0120] Lithium manganese oxide lithium ion sieve, polybutane glycol, hexamethylene diisocyanate, and dibutyltin diacid were mixed and added to dichloromethane. The mixture was stirred and reacted in a nitrogen glove box at 70°C for 5 hours. Subsequently, the mixture was granulated by extrusion and dried at 80°C for 20 hours to obtain primary lithium ion sieve particles.

[0121] The raw material addition ratio is: -OH, -NCO group ratio 1:3; the total concentration of lithium manganese oxide lithium ion sieve, polybutane glycol, and hexamethylene diisocyanate in the dichloromethane solution is 1.5 g / ml; the mass ratio of lithium ion sieve to polybutane glycol and hexamethylene diisocyanate is 15:1; and the amount of dibutyltin diacid added is 1% of the mass of hexamethylene diisocyanate.

[0122] S2: Preparation of polymers containing SS bonds

[0123] Cystamine was dissolved in N-methylpyrrolidone to obtain solution 1, and hexamethylene diisocyanate was dissolved in N-methylpyrrolidone to obtain solution 2. Solution 1 was slowly added dropwise to solution 2 while stirring continuously. After the addition was complete, the reaction was carried out at 50°C for 10 hours. The concentration of solution 1 and solution 2 was prepared to be 2 g / ml. After the reaction was completed, the polymer containing SS bonds was obtained by rotary evaporation and drying.

[0124] The molar ratio of cystamine to hexamethylene diisocyanate is 1.2:1;

[0125] S3: Lithium-ion sieve secondary polymerization coating

[0126] The primary lithium-ion sieve particles, dichloromethane, the polymer containing SS bonds synthesized in step S2, and dibutyltin diacid were mixed. The amount of dibutyltin diacid added was 1% of the mass of the polymer containing SS bonds, and the mass ratio of the primary lithium-ion sieve particles to the polymer containing SS bonds was 1:5%. The concentration of the primary lithium-ion sieve particles in the solution before the reaction was 1.5 g / ml. The mixture was stirred at 80°C for 5 h, then filtered and dried to obtain the lithium-ion sieve adsorbent.

[0127] Example 6

[0128] This embodiment provides a method for preparing a lithium adsorbent, including the following steps:

[0129] S1: Lithium-ion sieve primary polymerization granulation

[0130] Lithium manganese oxide lithium ion sieve, polybutane glycol, hexamethylene diisocyanate, and dibutyltin diacid were mixed and added to dichloromethane. The mixture was stirred and reacted in a nitrogen glove box at 50°C for 4 hours. Subsequently, the mixture was granulated by extrusion and dried at 60°C for 50 hours to obtain primary lithium ion sieve particles.

[0131] The raw material addition ratio is as follows: -OH to -NCO group ratio 1:2; the total concentration of lithium manganese oxide lithium ion sieve, polybutane glycol, and hexamethylene diisocyanate in the dichloromethane solution is 1.5 g / ml; the mass ratio of lithium ion sieve to polybutane glycol and hexamethylene diisocyanate is 10:1; and the amount of dibutyltin diacid added is 3% of the mass of hexamethylene diisocyanate.

[0132] S2: Preparation of polymers containing SS bonds

[0133] Cystamine was dissolved in N-methylpyrrolidone to obtain solution 1, and hexamethylene diisocyanate was dissolved in N-methylpyrrolidone to obtain solution 2. Solution 1 was slowly added dropwise to solution 2 while stirring continuously. After the addition was complete, the reaction was carried out at 30°C for 20 hours. The concentration of solution 1 and solution 2 was prepared to be 2 g / ml. After the reaction was completed, the polymer containing SS bonds was obtained by rotary evaporation and drying.

[0134] The molar ratio of cystamine to hexamethylene diisocyanate is 1.15:1;

[0135] S3: Lithium-ion sieve secondary polymerization coating

[0136] The primary lithium-ion sieve particles, dichloromethane, the polymer containing SS bonds synthesized in step S2, and dibutyltin diacid were mixed. The amount of dibutyltin diacid added was 3% of the mass of the polymer containing SS bonds. The mass ratio of the primary lithium-ion sieve particles to the polymer containing SS bonds was 1:1%, and the concentration of the primary lithium-ion sieve particles in the solution before the reaction was 1.5 g / ml. The reaction was stirred at 60 °C for 10 h, followed by filtration and drying to obtain the lithium-ion sieve adsorbent.

[0137] Comparative Example 1:

[0138] The difference from Example 1 is that cystamine is not added.

[0139] Performance testing:

[0140] Measure the brine concentration before adsorption and after adsorption equilibrium, and calculate the adsorption capacity according to the following formula.

[0141] The adsorption capacity of the adsorbent is: Q = V(C0 - C) / m;

[0142] Q is the adsorption capacity, mg / g; V is the adsorption liquid volume, L; m is the adsorbent mass, g; C0 and C are the lithium ion concentrations in the brine before adsorption and after adsorption equilibrium, respectively, mg / L.

[0143] The brine composition is as follows: COD: 4598 mg / L, Li + 30mg / L

[0144] The ratio of the adsorption capacity to the initial adsorption capacity after 100 cycles is used to obtain the capacity retention rate after 100 cycles.

[0145] The test results are shown in Table 1:

[0146] Table 1

[0147] Example 1 25.47 98.74 Example 2 23.67 94.51 Example 3 24.82 90.27 Example 4 24.98 91.47 Example 5 25.13 98.21 Example 6 25.18 98.34 Comparative Example 1 23.14 89.43

[0148] As can be seen from the data in the table above, compared to Example 1: Example 2, by adding organic matter containing SS bonds only during granulation, results in disulfide bonds existing only inside the particles. The particles lack a separate coating layer and there is no disulfide bond rearrangement between the coating layer and the core, thus affecting their cycling stability. Example 3 omits the primary granulation step of the lithium-ion sieve, essentially mixing the polymer containing disulfide bonds with the lithium-ion sieve. This results in poor particle formation and weak bonding between the polymer and the ion sieve, leading to reduced stability and affecting the lithium extraction performance of the ion sieve. Example 4 directly reacts cystamine with the primary lithium-ion sieve particles, causing disulfide bond and -NH-COO- rearrangement between the primary lithium-ion sieve particles and the first coating layer. However, the first coating layer only contains disulfide bonds, without any rearrangement of disulfide bonds and hydrogen bonds, which fails to effectively mitigate lithium-ion sieve loss, resulting in relatively low capacity retention after 100 cycles. However, compared to Comparative Example 1, due to the presence and rearrangement of SS and hydrogen bonds, each example can mitigate lithium-ion sieve loss to some extent.

Claims

1. A lithium adsorbent, characterized in that, It includes a lithium-ion sieve and a first coating layer, wherein the first coating layer includes a polymer containing -NH-COO- and SS groups; The first coating layer contains primary lithium-ion sieve particles, which include a lithium-ion sieve and a first polymer coated on the lithium-ion sieve, the first polymer having -NH-COO- groups.

2. The lithium adsorbent according to claim 1, characterized in that, The lithium-ion screen is a manganese-based lithium-ion screen. And / or, in the lithium adsorbent, the mass fraction of the polymer containing -NH-COO- and SS groups is 1% to 5%; And / or, the mass ratio of lithium ion screen to first polymer in the primary particles of the lithium ion screen is (2~5):1; And / or, the polymer containing -NH-COO- and SS groups is an amorphous polymer.

3. A method for preparing the lithium adsorbent according to claim 1 or 2, characterized in that, include: A polymer containing -NH-COO- and SS groups is coated onto the surface of the lithium-ion sieve to obtain a lithium adsorbent.

4. The method for preparing the lithium adsorbent according to claim 3, characterized in that, include: A single polymerization process is performed to coat the lithium-ion sieve once, resulting in lithium-ion sieve particles coated with a first polymer, wherein the first polymer has -NH-COO- groups. Secondary polymerization involves reacting the primary lithium-ion sieve particles with a second polymer containing SS bonds to obtain the lithium adsorbent.

5. The method for preparing the lithium adsorbent according to claim 4, characterized in that, The first polymer is end-capped with -NCO, and the second polymer is end-capped with -NH2 or -OH.

6. The method for preparing the lithium adsorbent according to claim 4, characterized in that, In the primary polymerization step, the lithium ion sieve, the -OH-containing polymer, and the first -NCO-containing compound are mixed to obtain a first mixture, which is then subjected to a primary polymerization reaction and granulation to obtain the primary lithium ion sieve particles.

7. The method for preparing the lithium adsorbent according to claim 6, characterized in that, The -OH-containing polymer is one or more of polybutanediol, polytetrahydrofuran ether, polyethylene glycol, and polypentylene glycol.

8. The method for preparing the lithium adsorbent according to claim 6, characterized in that, The first -NCO-containing compound is one or more of hexamethylene diisocyanate, toluene diisocyanate, methyl isocyanate, n-butyl isocyanate, tert-butyl isocyanate, phenyl isocyanate, p-chlorophenyl isocyanate, 3-chlorophenyl isocyanate, 3,4-dichlorophenyl isocyanate, p-methylphenyl isocyanate, isophorone diisocyanate, and phenylmethane triisocyanate.

9. The method for preparing the lithium adsorbent according to claim 6, characterized in that, The first aggregation step satisfies at least one of the following: a. The molar ratio of -OH to -NCO in the first mixture is 1:(2~3); b. The mass ratio of the lithium-ion sieve to the total amount of the -OH-containing polymer and the first -NCO-containing compound is (10~15):1; c. The first mixture further includes a first solvent, wherein the total concentration of the lithium ion sieve, the -OH-containing polymer, and the first -NCO-containing compound in the first mixture is 1 g / ml to 5 g / ml; d. The first mixture further includes a first solvent, which is one or more of dichloromethane, diethyl ether, toluene, and ethyl acetate; e. The first mixture further includes a first catalyst, wherein the amount of the first catalyst added is 1% to 3% of the mass of the first -NCO-containing compound; f. The first mixture further includes a first catalyst, which is one or more of dibutyltin diacid, palladium metal catalyst, and nickel metal catalyst; g. The temperature of the primary polymerization reaction is 50℃~70℃, and the reaction time is 3h~5h; h. After the granulation step, drying is carried out at a temperature of 60℃~80℃ for a time of 20h~50h.

10. The method for preparing the lithium adsorbent according to claim 4, characterized in that, The secondary polymerization step satisfies at least one of the following AG: A. The reaction temperature of the secondary polymerization step is 60℃~80℃, and the reaction time is 5h~10h; B. After the secondary polymerization reaction is completed, the reaction liquid is filtered and dried to separate the lithium adsorbent; C. The mass of the second polymer is 1% to 5% of the mass of the primary particles from the lithium-ion sieve; D. The reaction solution also includes a second solvent, and the content of primary lithium-ion sieve particles in the pre-reaction solution of the secondary polymerization reaction is 1 g / ml to 5 g / ml; E. The reaction solution also includes a second solvent, which is one or more of dichloromethane, diethyl ether, toluene, and ethyl acetate; F. The reaction solution also includes a second catalyst, the amount of which is 1% to 3% of the mass of the second polymer; G. The reaction solution also includes a second catalyst, which is one or more of dibutyltin diacid, palladium metal catalyst and nickel metal catalyst.

11. The method for preparing the lithium adsorbent according to claim 4, characterized in that, It also includes the preparation of the second polymer: a third polymerization reaction is carried out between an SS-containing compound and a second -NCO-containing compound to obtain the second polymer, wherein the SS-containing compound also has -NH2 or -OH.

12. The method for preparing the lithium adsorbent according to claim 11, characterized in that, The reaction temperature of the third polymerization reaction is 30℃~50℃, and the reaction time is 10h~20h.

13. The method for preparing the lithium adsorbent according to claim 11, characterized in that, The molar ratio of the SS-containing compound to the second -NCO-containing compound is (1.1~1.2):

1.

14. The method for preparing the lithium adsorbent according to claim 11, characterized in that, The SS-containing compound is one or more of cystamine, 4,4'-diaminodiphenyl disulfide, 2-hydroxyethyl disulfide, bis(2-hydroxyethyl) disulfide, 3,3-dihydroxydiphenyl disulfide, 4,4-dihydroxydiphenyl disulfide and 2,2-diaminodiphenyl disulfide.

15. The method for preparing the lithium adsorbent according to claim 11, characterized in that, The second -NCO-containing compound is one or more of hexamethylene diisocyanate, toluene diisocyanate, methyl isocyanate, n-butyl isocyanate, tert-butyl isocyanate, phenyl isocyanate, p-chlorophenyl isocyanate, 3-chlorophenyl isocyanate, 3,4-dichlorophenyl isocyanate, p-methylphenyl isocyanate, isophorone diisocyanate, and phenylmethane triisocyanate.

16. The method for preparing the lithium adsorbent according to claim 11, characterized in that, The reaction solution of the third polymerization reaction also includes a third solvent, which is one or more of dimethyl sulfoxide, N,N-dimethylformamide, dichloromethane, tetrahydrofuran, and N-methylpyrrolidone.

17. The method for preparing the lithium adsorbent according to claim 16, characterized in that, The third polymerization reaction includes: adding solution A dropwise to solution B and stirring, and then reacting at 30℃~50℃ for 10h~20h before rotary drying to separate the second polymer. Solution A is a mixture of SS-containing compound and third solvent, and solution B is a mixture of second -NCO-containing compound and third solvent.

18. The method for preparing the lithium adsorbent according to claim 17, characterized in that, The concentration of the solute in solution A and / or solution B is 1 g / ml to 5 g / ml.

19. The application of a lithium adsorbent according to claim 1 or 2, or a lithium adsorbent prepared by the method according to any one of claims 3-18, in selective lithium extraction.

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