Lithium-printed ion-sieve composite material, and preparation method and use thereof

Abstract

The application provides a lithium imprinting ion sieve composite material and a preparation method and application thereof, the lithium imprinting ion sieve composite material is composed of lithium ion imprinting polymer and lithium ion sieve; the lithium ion imprinting polymer is synthesized by using a specific crown ether crosslinking agent, the lithium ion imprinting polymer can play the effect of a granulating binder of the lithium ion sieve, can avoid the problem that the active sites of the lithium ion sieve are covered due to the use of a traditional binder, and can reduce the lithium extraction capacity, and improves the stability of use; meanwhile, the specific crosslinking agent has diversity, contains various hydrogen-containing groups (such as carboxyl, amide, hydroxyl and amine), provides various hydrogen bond crosslinking in the polymer, so that the lithium imprinting ion sieve composite material can be water-soluble and swollen in the lithium extraction solution, the swelling rate is more than 100%, the wettability of the lithium ion sieve in water is improved, and the lithium adsorption performance is improved.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion resource extraction technology, and relates to a lithium-imprinted ion sieve composite material, its preparation method and application. Background Technology

[0002] Currently, liquid lithium resources, such as salt lake brines, are generally characterized by low lithium-ion concentrations, high magnesium-to-lithium ratios, complex compositions, and numerous associated elements. Coupled with a lack of mature separation and extraction technologies, liquid lithium resources cannot yet be industrially developed and utilized on a large scale. To achieve the separation and extraction of lithium ions from liquid lithium resources, researchers have successively developed methods such as calcination impregnation, solar evaporation, co-precipitation, solvent extraction, and adsorption.

[0003] Among these methods, adsorption is a relatively ideal technique for extracting lithium ions from seawater or salt lakes. Adsorption uses adsorbents selectively targeting lithium ions to adsorb them. Based on the mechanism of ion exchange, after the target lithium ions are extracted (in a lithium-depleted state), they can be reintroduced and react to form a composite material (in a lithium-rich state). Therefore, it is more suitable for the separation and enrichment of lithium ions in large-scale liquid environments, and also has the advantages of low energy consumption, environmental friendliness, and ease of operation.

[0004] The key to the adsorbent method is the use of high-performance and highly stable lithium-ion adsorbents. Lithium-ion sieves are a special type of lithium-ion adsorbent with high adsorption capacity and high selectivity. Currently, lithium-ion sieves mainly include three categories: manganese-based lithium-ion sieves (LMO), titanium-based lithium-ion sieves (LTO), and aluminum-based adsorbents (LiAl-LDHs), as well as phosphate, silicate, and antimonate materials. However, regardless of the type of lithium-ion sieve, the synthesized product is mostly in powder form. In industrial applications, it has poor flowability, poor water wettability, low circulation efficiency, is not easy to separate from aqueous environments and is easily lost, which can lead to large pressure drops and high energy consumption in column operations, thus hindering industrial applications. Existing technologies usually use granulation, film formation, foaming, and electrospinning for reshaping, but these methods all use polymers as binders or loading materials, which can cause the active sites of the lithium-ion sieve to be covered by the binder, resulting in a decrease in lithium extraction capacity and rate.

[0005] Therefore, a new technical solution needs to be developed to avoid the impact of binder use on lithium-ion sieve molding, thereby obtaining a high-performance and highly stable lithium extraction material. Summary of the Invention

[0006] In view of the problems existing in the prior art, the purpose of the present invention is to provide a lithium-imprinted ion sieve composite material, its preparation method and application. The lithium-imprinted ion sieve composite material is composed of a lithium-ion imprinted polymer and a lithium-ion sieve. The lithium-ion imprinted polymer is synthesized using a specific crown ether crosslinking agent, which can replace the binder to fix the lithium-ion sieve without covering the active sites. It can also enhance water absorption and swelling properties, thereby improving the wettability of the lithium-ion sieve and effectively improving the performance of lithium adsorption and the stability of use.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a method for preparing a lithium-imprinted ion sieve composite material, the method comprising:

[0009] The polymer monomer, initiator, lithium salt, lithium ion sieve, branched polymer crosslinking agent and crown ether crosslinking agent with the structure shown in Formula I are mixed and polymerized and aged sequentially to obtain a precursor; the obtained precursor is subjected to delithiation treatment to obtain lithium-imprinted ion sieve composite material.

[0010]

[0011] In Formula I, R1, R2, R3 and R4 represent hydrogen or hydrogen substituents, and at least one of R1, R2, R3 and R4 is a hydrogen substituent, which includes an end group having the structure shown in Formula II.

[0012]

[0013] The preparation method of this invention involves compounding a lithium-ion imprinted polymer with a lithium-ion sieve to obtain the lithium-ion imprinted ion sieve composite material. The lithium-ion imprinted polymer is obtained by polymerizing a monomer (such as acrylic acid and its derivatives) with a specific crown ether crosslinking agent, a branched crosslinking polymer crosslinking agent, and a lithium salt in solution. The lithium-ion imprinted polymer is an adsorbent material, and its preparation process introduces Li... + As a template, its coordination structure (i.e., "imprinted cavities") and position remain unchanged after delithiation, thus exhibiting an affinity for lithium. Therefore, this invention, by obtaining a specific lithium-ion imprinted polymer and using it as a granulation binder for lithium-ion sieves, avoids the problem of lithium-ion sieve active sites being masked, leading to a decrease in delithiation capacity, which is caused by the use of traditional binders, thereby improving the stability of use. At the same time, the specific crosslinking agent is diverse, containing various hydrogen-containing groups (such as carboxyl, amide, hydroxyl, and amine groups), providing diverse hydrogen bond crosslinks within the polymer. This allows the lithium-imprinted ion sieve composite material to absorb water and swell in the lithium extraction / delithiation solution, achieving a swelling rate of over 100%, improving the wettability of the lithium-ion sieve in water, and thus enhancing its lithium adsorption performance.

[0014] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The technical objectives and beneficial effects of the present invention can be better achieved and realized through the following technical solutions.

[0015] As a preferred embodiment of the present invention, a method for preparing a crown ether crosslinking agent having the structure shown in Formula I includes:

[0016] 4,5-Diaminobenzo-12-crown-4 was heated under alkaline conditions to carry out the first reaction with a substance having the structure shown in Formula III, and the crown ether crosslinking agent was obtained after purification.

[0017]

[0018] In Formula III, X is Cl or Br.

[0019] In Formula III, when X is Cl, the obtained substance is 2-chloroethyl methacrylate; when X is Br, the obtained substance is 2-bromoethyl methacrylate; in the preparation method of the present invention, any one or a combination of two of 2-chloroethyl methacrylate and 2-bromoethyl methacrylate can be used simultaneously.

[0020] It should be noted that after the first reaction of 4,5-diaminobenzo-12-crown-4 with a substance having the structure shown in Formula III, different crown ether crosslinking agents can be obtained depending on the degree of reaction. This results in the two amino groups on 4,5-diaminobenzo-12-crown-4 being co-substituted with 1, 2, 3, or 4 end groups (i.e., ethyl methacrylate groups) having the structure shown in Formula II as substituents for the hydrogen. It can be understood that the unsubstituted positions are occupied by -H. For example, a representative example is the substance shown in Formula IV:

[0021]

[0022] Preferably, the heating temperature of the first reaction is 60 to 80°C, for example, it can be 60°C, 65°C, 70°C, 75°C or 80°C, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0023] Preferably, the reaction time is 4 to 6 hours, for example, 4 hours, 4.5 hours, 5 hours, 5.5 hours or 6 hours, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0024] Preferably, the molar ratio of the 4,5-diaminobenzo-12-crown-4 to the substance having the structure shown in Formula III is 1:(2.2 to 3), for example, it can be 1:2.2, 1:2.3, 1:2.4, 1:2.5, 1:2.6, 1:2.7, 1:2.8, 1:2.9 or 1:3, etc., but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0025] Preferably, the molar ratio of the substance having the structure shown in Formula III to the alkaline substance maintaining the alkaline conditions is 1:(3 to 5), for example, it can be 1:3, 1:3.2, 1:3.4, 1:3.6, 1:3.8, 1:4, 1:4.2, 1:4.4, 1:4.6, 1:4.8 or 1:5, etc., but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0026] As a preferred embodiment of the present invention, the method for preparing the 4,5-diaminobenzo-12-crown-4 includes:

[0027] Benzo-12-crown-4 was dissolved in chloroform, concentrated nitric acid was added, and the mixture was stirred at room temperature to carry out a nitration reaction. After purification, 4,5-dinitrobenzo-12-crown-4 was obtained. The obtained 4,5-dinitrobenzo-12-crown-4 was dissolved in hydrochloric acid solution, and then placed in an ice bath with zinc powder added and stirred. After the zinc powder was completely dissolved, the ice bath was removed, and the mixture was stirred at room temperature. After the reaction was completed, alkali solution was added for neutralization. The filtrate was filtered and purified to obtain 4,5-diaminobenzo-12-crown-4.

[0028] As a preferred embodiment of the present invention, the branched polymer crosslinking agent contains vinyl groups for polymerization.

[0029] Preferably, the method for preparing the branched polymer crosslinking agent includes:

[0030] Branched polyethyleneimine is heated with a substance having the structure shown in Formula III under alkaline conditions to carry out a second reaction, and the branched polymer crosslinking agent is obtained after purification.

[0031]

[0032] In Formula III, X is Cl or Br.

[0033] In this invention, the substance having the structure shown in Formula III used to prepare the crown ether crosslinking agent and the branched polymer crosslinking agent can be the same or different. For example, 2-chloroethyl methacrylate is used to prepare the crown ether crosslinking agent, and 2-bromoethyl methacrylate is used to prepare the branched polymer crosslinking agent.

[0034] Preferably, the alkaline condition for the second reaction is pH = 10 to 11, for example, it can be 10, 10.1, 10.2, 10.3, 10.4, 10.5, 10.6, 10.7, 10.8, 10.9 or 11, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0035] Preferably, the alkaline solution comprises sodium hydroxide solution and / or potassium hydroxide solution.

[0036] Preferably, the heating temperature of the second reaction is 70 to 90°C, for example, 70°C, 75°C, 80°C, 85°C or 90°C, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0037] Preferably, the second reaction time is 6 to 10 hours, for example, 6 hours, 7 hours, 8 hours, 9 hours or 10 hours, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0038] Preferably, the amino group content of the branched polyethyleneimine is 15-20 mmol / g (tested by titration), for example, it can be 15 mmol / g, 16 mmol / g, 17 mmol / g, 18 mmol / g, 19 mmol / g or 20 mmol / g, etc., but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0039] Preferably, the molar ratio of the branched polyethyleneimine to the substance having the structure shown in Formula III is 1:(1 to 1.1), for example, 1:1, 1:1.01, 1:1.02, 1:1.03, 1:1.04, 1:1.05, 1:1.06, 1:1.07, 1:1.08, 1:1.09 or 1:1, but is not limited to the listed values; other unlisted values ​​within the above range are also applicable.

[0040] As a preferred technical solution of the present invention, the preparation method includes:

[0041] First, the polymer monomer, the initiator, the branched polymer crosslinking agent, and the crown ether crosslinking agent are dissolved in the lithium salt solution and stirred evenly. Then, the lithium ion sieve is added to form a suspension, and the polymerization reaction is carried out on the suspension.

[0042] Preferably, the concentration of lithium salt in the lithium salt solution is 0.8 to 1.2 mol / L, for example, it can be 0.8 mol / L, 0.9 mol / L, 1 mol / L, 1.1 mol / L or 1.2 mol / L, etc., but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0043] As a preferred embodiment of the present invention, the mass ratio of the branched polymer crosslinking agent to the crown ether crosslinking agent is 1:(2-6), for example, it can be 1:2, 1:2.2, 1:2.4, 1:2.6, 1:2.8, 1:3, 1:3.2, 1:3.4, 1:3.6, 1:3.8, 1:4, 1:4.2, 1:4.4, 1:4.6, 1:4.8, 1:5, 1:5.2, 1:5.4, 1:5.6, 1:5.8 or 1:6, etc., but is not limited to the listed values, other unlisted values ​​within the above range are also applicable.

[0044] The crown ether crosslinking agent described in this invention can adjust the swelling rate of the final product and affect the lithium extraction capacity.

[0045] Preferably, the mass ratio of the lithium-ion sieve to the polymer monomer is 1:(0.8 to 1.5), for example, it can be 1:0.8, 1:0.85, 1:0.9, 1:0.95, 1:1, 1:1.05, 1:1.1, 1:1.15, 1:1.2, 1:1.25, 1:1.3, 1:1.35, 1:1.4, 1:1.45 or 1:1.5, etc., but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0046] Preferably, the ratio of the total mass of the branched polymer crosslinking agent and the crown ether crosslinking agent to the mass of the polymer monomer is (0.3 to 0.7):1, for example, it can be 0.3:1, 0.4:1, 0.5:1, 0.6:1 or 0.7:1, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0047] In this invention, the total amount of polymer (including polymer monomers and crosslinking agents) must be appropriate to ensure sufficient bonding to the lithium ion sieve without being excessive and reducing lithium extraction performance.

[0048] Preferably, the ratio of the total mass of the polymeric monomer, the branched polymer crosslinking agent, and the crown ether crosslinking agent to the mass of the initiator is 1:(0.03 to 0.05), for example, it can be 1:0.03, 1:0.035, 1:0.04, 1:0.045, or 1:0.05, but it is not limited to the values ​​listed above. Other unlisted values ​​within the above range are also applicable.

[0049] As a preferred embodiment of the present invention, the lithium-ion sieve is in a lithium-rich state.

[0050] Preferably, the lithium-ion sieve in the lithium-rich state includes LiMn2O4, Li 1.5 Mn2O4, Li1.33 Mn 1.67 O4, Li 1.6 Mn 1.6 O4, Li2TiO3, Li4Ti5O 12 At least one of them, for example typical but non-limiting examples include LiMn2O4 and Li 1.5 Combinations of Mn2O4 and Li 1.33 Mn 1.67 O4 and Li 1.6 Mn 1.6 Combinations of O4, Li2TiO3 and Li4Ti5O 12 Combinations of LiMn2O4 and Li 1.6 Mn 1.6 Combinations of O4, etc.

[0051] Preferably, the polymeric monomer includes at least one of (meth)acrylic acid, (meth)acrylamide, (meth)acrylic acid hydroxyethyl ester, or 2AM12C4, for example, typical but non-limiting combinations include combinations of (meth)acrylic acid and (meth)acrylamide, combinations of (meth)acrylic acid and (meth)acrylic acid hydroxyethyl ester, or combinations of (meth)acrylic acid and 2AM12C4, etc.

[0052] Preferably, the initiator includes a thermal initiator and / or a photoinitiator.

[0053] Preferably, the thermal initiator comprises at least one of azobisisobutyronitrile, azobisisoheptanenitrile, dimethyl azobisisobutyrate, benzoyl peroxide, or cumene hydroperoxide. Typical but non-limiting examples of combinations include a combination of azobisisobutyronitrile and azobisisoheptanenitrile, a combination of azobisisobutyronitrile and dimethyl azobisisobutyrate, or a combination of benzoyl peroxide and cumene hydroperoxide.

[0054] Preferably, the photoinitiator includes at least one of benzoin dimethyl ether, 2-hydroxy-2-methyl-1-phenylpropanone, or 1-hydroxycyclohexyl ketone. Typical but non-limiting examples of combinations include combinations of benzoin dimethyl ether and 2-hydroxy-2-methyl-1-phenylpropanone, combinations of benzoin dimethyl ether and 1-hydroxycyclohexyl ketone, or combinations of 2-hydroxy-2-methyl-1-phenylpropanone and 1-hydroxycyclohexyl ketone.

[0055] Preferably, the lithium salt comprises lithium chloride and / or lithium nitrate.

[0056] Preferably, the lithium salt solution contains solvent A and solvent B, wherein solvent A includes methanol and / or ethanol; and solvent B includes DMSO and / or DMF.

[0057] As a preferred embodiment of the present invention, the polymerization reaction is carried out under heating and / or ultraviolet light irradiation.

[0058] Preferably, the aging temperature is 40-60°C, for example, 40°C, 45°C, 50°C, 55°C or 60°C, and the time is 6-24h, for example, 6h, 12h, 16h, 20h or 24h, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0059] Preferably, the aging process is followed by drying, and the drying method includes freeze drying or heat drying.

[0060] Preferably, the method for delithiation includes acid washing.

[0061] Preferably, the pickling solution includes hydrochloric acid with a concentration of 0.3 to 0.7 mol / L, such as 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, or 0.7 mol / L, but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0062] Preferably, the pickling is performed by controlling the amount of precursor and pickling solution according to a solid-liquid ratio S / L of (0.8-1.2) g:100 mL, such as 0.8 g:100 mL, 0.9 g:100 mL, 1 g:100 mL, 1.1 g:100 mL or 1.2 g:100 mL, etc., but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0063] Preferably, the pickling time is 12 to 36 hours, such as 12 hours, 16 hours, 20 hours, 24 hours, 28 hours, 32 hours or 36 hours, but it is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0064] In a second aspect, the present invention provides a lithium-imprinted ion sieve composite material, which is obtained according to the preparation method described in the first aspect.

[0065] Thirdly, the present invention provides an application of the lithium-imprinted ion sieve composite material described in the second aspect, the application including lithium extraction from liquid lithium ore resources.

[0066] Compared with existing technical solutions, the present invention has at least the following beneficial effects:

[0067] The preparation method of this invention involves compounding a specific lithium-ion imprinted polymer with a lithium-ion sieve to obtain the lithium-ion imprinted ion sieve composite material. The resulting specific lithium-ion imprinted polymer, used as a granulation binder for the lithium-ion sieve, avoids the problem of reduced delithiation capacity caused by the masking of active sites on the lithium-ion sieve due to the use of traditional binders, thus improving stability in use. Simultaneously, the lithium-ion imprinted polymer prepared using a specific crosslinking agent exhibits diversity, containing various hydrogen-containing groups (such as carboxyl, amide, hydroxyl, and amine groups), providing diverse hydrogen bond crosslinks within the polymer. This allows the lithium-ion imprinted ion sieve composite material to absorb water and swell in the lithium extraction / delithiation solution, achieving a swelling rate of over 100%, thereby improving the wettability of the lithium-ion sieve in water and enhancing its lithium adsorption performance. Attached Figure Description

[0068] Figure 1 These are actual images of the lithium-imprinted ion sieve composite material obtained in Example 1 before and after swelling. Detailed Implementation

[0069] The technical solution of the present invention will be further illustrated below through specific embodiments.

[0070] Those skilled in the art will understand that the embodiments described are merely illustrative of the invention and should not be construed as limiting the invention.

[0071] Example 1

[0072] This embodiment provides a method for preparing a lithium-imprinted ion sieve composite material, the method comprising:

[0073] [Preparation of crown ether crosslinking agents]

[0074] (1-1) Preparation of 4,5-dinitrobenzo-12-crown-4

[0075] Benzo-12-crown-4 was dissolved in chloroform, concentrated nitric acid was added, and the mixture was stirred at room temperature for 7 days for nitration. After the reaction was completed, an equal volume of distilled water and chloroform were added for extraction to separate the organic phase. An equal volume of distilled water was added for washing until the aqueous phase was neutral. The organic phase was concentrated to obtain the crude product. The crude product was dissolved in ethyl acetate and recrystallized in petroleum ether. After drying, 4,5-dinitrobenzo-12-crown-4 was obtained with a yield of 78%.

[0076] In step (1-1), the feeding ratio of benzo-12-crown-4, concentrated nitric acid, and chloroform is controlled to be 1g:40mL:25mL; the ratio of crude product, ethyl acetate, and petroleum ether is controlled to be 1g:5mL:200mL.

[0077] The obtained 4,5-dinitrobenzo-12-crown-4 was subjected to nuclear magnetic resonance (NMR) analysis. The 1H-NMR (300 MHz, CDCl3) results were: 3.78 (4H, OCH2CH2O), 3.95–3.97 (4H, OCH2CH2O), 4.35–4.37 (4H, OCH2CH2O), 7.45 (2H, ArH).

[0078] (1-2) Preparation of 4,5-diaminobenzo-12-crown-4

[0079] The 4,5-dinitrobenzo-12-crown-4 obtained in step (1-1) was dissolved in 20 wt% hydrochloric acid solution, then placed in an ice bath and zinc powder was added and stirred. After the zinc powder was completely dissolved, the ice bath was removed, and the reaction was stirred at room temperature. After the reaction was completed, 1M NaOH was added to neutralize the solution to neutrality. The solution was filtered, and the filtrate was extracted with an equal volume of chloroform. The extraction was repeated 3 times. The organic phases were combined and subjected to rotary evaporation under reduced pressure to obtain a solid crude product. The solid crude product was dissolved in chloroform and then recrystallized in petroleum ether. After drying, 4,5-diaminobenzo-12-crown-4 was obtained with a yield of 51%.

[0080] In steps (1-2), the feeding ratio of 4,5-dinitrobenzo-12-crown-4, 20wt% hydrochloric acid solution, and zinc powder is controlled to be 1g:100mL:10g; the ratio of the solid crude product, chloroform, and petroleum ether is controlled to be 1g:5mL:200mL.

[0081] The obtained 4,5-diaminobenzo-12-crown-4 was subjected to nuclear magnetic resonance (NMR) analysis. The 1H-NMR (300 MHz, CDCl3) results were: 3.78 (4H, OCH2CH2O), 3.95–3.97 (4H, OCH2CH2O), 4.35–4.37 (4H, OCH2CH2O), 5.22 (4H, NH2), and 6.84 (2H, ArH).

[0082] (1-3) Preparation of crown ether crosslinking agent

[0083] The 4,5-diaminobenzo-12-crown-4 obtained in step (1-2) was dissolved in ethanol, 2-chloroethyl methacrylate and 1M NaOH solution were added, the mixture was heated to 70℃ and refluxed for 5 h, the crude product was obtained by rotary evaporation and dissolved in dichloromethane (DCM), filtered and washed with an equal volume of water, repeated 3 times, and then subjected to silica gel column chromatography with chloroform as eluent. After drying, the crown ether crosslinking agent was obtained with a yield of 68%.

[0084] In steps (1-3), the molar ratio of 4,5-diaminobenzo-12-crown-4 to 2-chloroethyl methacrylate is controlled to be 1:2.5; the molar ratio of 2-chloroethyl methacrylate to NaOH is controlled to be 1:4.

[0085] [Preparation of branched polymer crosslinking agents]

[0086] (2) Dissolve branched polyethyleneimine and 2-chloroethyl methacrylate in ethanol, add 1M NaOH solution to adjust pH to 10, heat to 80℃ and stir for 8h. After the reaction is completed, concentrate the crude product and dissolve it with DCM. After filtration, add an equal volume of aqueous solution to wash until the aqueous phase is neutral. Take the organic phase and dry to obtain the branched polymer crosslinking agent.

[0087] In step (2), the amino group content of the branched polyethyleneimine is controlled to be 17.35 mmol / g (titration method); the molar ratio of the amino group of the branched polyethyleneimine to the molar ratio of 2-chloroethyl methacrylate is controlled to be 1:1.

[0088] [Preparation of precursors]

[0089] (3) Dissolve the polymer monomer, the crown ether crosslinking agent obtained in step (1-3), the branched polymer crosslinking agent obtained in step (2), and the thermal initiator azobisisobutyronitrile in a lithium salt solution, stir evenly, add lithium-rich lithium ion sieve LiMn2O4, sonicate to form a suspension, heat to 80°C to carry out the polymerization reaction, obtain a gel, transfer the gel to a mold and age at 50°C for 12 hours, and then dry at 80°C to obtain the precursor;

[0090] In step (3), the polymer monomer is controlled to be a mixture of methacrylic acid, acrylamide, and hydroxyethyl methacrylate in a molar ratio of 2:1.2:0.8; the mass ratio of the crown ether crosslinking monomer to the branched polymer crosslinking agent is controlled to be 4:1; the mass ratio of the lithium ion sieve, the polymer monomer, to the total mass of the branched polymer crosslinking agent and the crown ether crosslinking agent is controlled to be 1:1:0.5; the mass of the initiator is controlled to be 3% of the total mass of the polymer monomer, the branched polymer crosslinking agent, and the crown ether crosslinking agent; the lithium salt solution is a solution of lithium chloride dissolved in DMF / ethanol (v / v = 1 / 3) with a concentration of 1M.

[0091] [Preparation of Lithium-Imprinted Ion Sieve Composite Materials]

[0092] (4) The precursor obtained in step (3) was added to a 0.5 mol / L hydrochloric acid solution with a solid-liquid ratio of 1 g: 100 mL. After ultrasonic degassing, it was shaken in a shaker at room temperature for 24 h to allow lithium ions in the precursor to be fully removed. Then it was ultrasonically washed with methanol and water respectively and dried to obtain lithium imprinted ion sieve composite material.

[0093] Example 2

[0094] This embodiment provides a method for preparing a lithium-imprinted ion sieve composite material. The preparation method adjusts the amino group content (titration method) of branched polyethyleneimine in step (2) from 17.35 mmol / g to 19.63 mmol / g. Except for the above, the other conditions are exactly the same as in Example 1.

[0095] Example 3

[0096] This embodiment provides a method for preparing a lithium-imprinted ion sieve composite material. The preparation method adjusts the amino group content (titration method) of branched polyethyleneimine in step (2) from 17.35 mmol / g to 15.24 mmol / g. Except for the above, the other conditions are exactly the same as in Example 1.

[0097] Example 4

[0098] This embodiment provides a method for preparing lithium-imprinted ion sieve composite materials, wherein step (3) of the preparation method is as follows:

[0099] The polymer monomer, the crown ether crosslinking agent obtained in step (1-3), the branched polymer crosslinking agent obtained in step (2), and the photoinitiator benzoin dimethyl ether were dissolved in a lithium salt solution. After stirring evenly, lithium-rich lithium ion sieve LiMn2O4 was added, and a suspension was formed by ultrasonication. The polymerization reaction was carried out by turning on the ultraviolet lamp to obtain a sol solution. The sol was transferred to a mold and aged at 50°C for 12 hours. Then it was dried at 80°C to obtain the precursor.

[0100] In step (3), the polymer monomer is controlled to be a mixture of methacrylic acid, acrylamide, hydroxyethyl methacrylate and 2AM124 in a molar ratio of 1.8:1:0.2:1; the mass ratio of the crown ether crosslinking monomer and the branched polymer crosslinking agent is controlled to be 2:1; the mass ratio of the lithium ion sieve, the polymer monomer, and the total mass of the branched polymer crosslinking agent and the crown ether crosslinking agent is controlled to be 1:1:0.5; the mass of the initiator is controlled to be 5% of the total mass of the polymer monomer, the branched polymer crosslinking agent and the crown ether crosslinking agent; the lithium salt solution is a solution of lithium nitrate dissolved in DMSO / methanol (v / v = 1 / 3) with a concentration of 1M.

[0101] Apart from the above, all other conditions are exactly the same as in Example 1.

[0102] Example 5

[0103] This embodiment provides a method for preparing a lithium-imprinted ion sieve composite material. In step (3), the ratio of the mass of the lithium ion sieve, the mass of the polymer monomer, to the total mass of the branched polymer crosslinking agent and the crown ether crosslinking agent is adjusted from 1:1:0.5 to 1:1:0.3. Except for the above, the other conditions are exactly the same as in Example 1.

[0104] Example 6

[0105] This embodiment provides a method for preparing a lithium-imprinted ion sieve composite material. In step (3), the ratio of the mass of the lithium ion sieve, the mass of the polymer monomer, and the total mass of the branched polymer crosslinking agent and crown ether crosslinking agent is adjusted from 1:1:0.5 to 1:1:0.7. Except for the above, the other conditions are exactly the same as in Example 1.

[0106] Example 7

[0107] This embodiment provides a method for preparing a lithium-imprinted ion sieve composite material. In step (3) of the preparation method, the drying after aging is adjusted to freeze drying at -80°C for 12 hours; the mass ratio of the crown ether crosslinking monomer and the branched polymer crosslinking agent is adjusted from 2:1 to 6:1; the mass ratio of the lithium ion sieve, the mass of the polymer monomer, and the total mass of the branched polymer crosslinking agent and the crown ether crosslinking agent is adjusted from 1:1:0.5 to 1:0.8:0.4. Except for the above, the other conditions are exactly the same as in Example 1.

[0108] Example 8

[0109] This embodiment provides a method for preparing a lithium-imprinted ion sieve composite material. In step (3) of the preparation method, the ratio of the mass of the lithium ion sieve, the mass of the polymer monomer, and the total mass of the branched polymer crosslinking agent and the crown ether crosslinking agent is adjusted from 1:1:0.5 to 1:1.5:0.75.

[0110] Comparative Example 1

[0111] This comparative example provides a method for preparing a lithium-imprinted ion sieve composite material. The preparation method does not include steps (1-1), (1-2), and (1-3). The crown ether crosslinking agent is not used in step (3). Except for the above, the other conditions are exactly the same as in Example 1.

[0112] Comparative Example 2

[0113] This comparative example provides a method for preparing a lithium-imprinted ion sieve composite material. The preparation method does not include step (2), and the branched polymer crosslinking agent is not used in step (3). Except for the above, the other conditions are exactly the same as those in Example 1.

[0114] Comparative Example 3

[0115] This comparative example provides a method for preparing a lithium-ion adsorbent material. The method uses polyvinyl chloride as a binder and employs conventional granulation techniques, specifically including:

[0116] LiMn2O4 and PVC were mixed and dispersed in N-methylpyrrolidone to obtain a first solution. The first solution was then dripped into water with an injection agent to form particles with a particle diameter of 2-4 mm. The obtained particles were washed with deionized water and dried at 80°C for 12 h to obtain a shaped lithium-ion adsorbent material precursor. After acid leaching and drying, the lithium-ion adsorbent material was obtained.

[0117] Testing and Characterization:

[0118] I. Water Absorption Test: After drying the sample to constant weight, weigh it (m0). Then, immerse it in neutral (deionized water) and acidic solutions (0.5M hydrochloric acid aqueous solution) at room temperature, respectively. After standing for 24 hours, remove it, absorb excess water with filter paper, and weigh it (m1). The water absorption rate is calculated using the following formula:

[0119]

[0120] A higher water absorption rate indicates a higher swelling rate. Figure 1 The lithium-imprinted ion sieve composite material obtained in Example 1 before water absorption and swelling ( Figure 1 (a) and after water absorption and swelling ( Figure 1 As shown in the physical image of (b), after absorbing water and swelling, the volume expands significantly but the material structure remains stable.

[0121] II. Adsorption performance test:

[0122] Adsorption capacity test: The sample to be tested was immersed in a lithium-containing solution (containing 0.05 mol / L lithium chloride) at a solid-liquid ratio of 1 g:1000 mL. The solution was shaken at 100 rpm for 24 hours at 25°C to ensure adsorption equilibrium was reached. The Li content in the solution was determined using ICP-OES. + The content of . Adsorption capacity Q e The formula for calculating (mg / g) is as follows:

[0123]

[0124] In the formula, C0 (mg / L) represents Li + The initial concentration of C; e (mg / L) is the concentration of lithium ions when adsorption equilibrium is reached; V(L) is the volume of the solution; m(g) is the mass of the sample to be tested.

[0125] Table 1

[0126] Example 1 125.3 24.22 98.22 Example 2 112.4 22.36 99.03 Example 3 133.1 25.65 96.78 Example 4 108.7 20.05 99.25 Example 5 138.9 23.45 95.35 Example 6 104.2 22.27 98.56 Example 7 114.5 18.78 99.58 Example 8 95.65 26.64 99.17 Comparative Example 1 142.25 19.24 90.51 Comparative Example 2 65.25 20.25 99.25 Comparative Example 3 1.02 18.65 98.24

[0127] As can be seen from the above, the lithium-ion imprinted polymer obtained by polymerizing the polymer monomer with a specific crown ether crosslinking agent, a branched crosslinking polymer crosslinking agent, and lithium salt in solution can be used as a granulation binder for lithium-ion sieves. This avoids the problem of lithium-ion sieve active sites being masked and resulting in a decrease in delithiation capacity caused by the use of traditional binders, thus improving the stability of use. At the same time, the specific crosslinking agent is diverse, containing a variety of hydrogen-containing groups (such as carboxyl, amide, hydroxyl, and amine groups), providing diverse hydrogen bond crosslinks within the polymer. This allows the lithium-imprinted ion sieve composite material to absorb water and swell in the lithium extraction / delithiation solution, achieving a swelling rate of over 100%, thereby improving the wettability of the lithium-ion sieve in water and thus enhancing its lithium adsorption performance.

[0128] This invention illustrates the detailed process equipment and process flow through the above embodiments. However, this invention is not limited to the detailed process equipment and process flow described above, meaning that this invention does not necessarily depend on the detailed process equipment and process flow to be implemented. Those skilled in the art should understand that any improvements to this invention, equivalent substitutions of raw materials for the product of this invention, addition of auxiliary components, and selection of specific methods, all fall within the protection scope and disclosure scope of this invention.

[0129] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0130] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0131] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A method for preparing a lithium-imprinted ion sieve composite material, characterized in that, The preparation method includes: The polymer monomer, initiator, lithium salt, lithium ion sieve, branched polymer crosslinking agent and crown ether crosslinking agent with the structure shown in Formula I are mixed and polymerized and aged sequentially to obtain a precursor; the obtained precursor is subjected to delithiation treatment to obtain a lithium-imprinted ion sieve composite material. In Formula I, R1, R2, R3 and R4 represent hydrogen or hydrogen substituents, and at least one of R1, R2, R3 and R4 is a hydrogen substituent, which includes an end group having the structure shown in Formula II. ； The lithium-imprinted ion sieve composite material is composed of a lithium-ion imprinted polymer and a lithium-ion sieve, wherein the lithium-ion imprinted polymer serves as a granulation binder for the lithium-ion sieve.

2. The preparation method according to claim 1, characterized in that, Methods for preparing crown ether crosslinking agents having the structure shown in Formula I include: 4,5-Diaminobenzo-12-crown-4 was heated under alkaline conditions to carry out the first reaction with a substance having the structure shown in Formula III, and the crown ether crosslinking agent was obtained after purification. In Formula III, X is Cl or Br.

3. The preparation method according to claim 2, characterized in that, The heating temperature for the first reaction is 60~80℃.

4. The preparation method according to claim 2, characterized in that, The first reaction takes 4 to 6 hours.

5. The preparation method according to claim 2, characterized in that, The molar ratio of the 4,5-diaminobenzo-12-crown-4 to the substance having the structure shown in Formula III is 1:(2.2~3).

6. The preparation method according to claim 2, characterized in that, The molar ratio of the substance having the structure shown in Formula III to the alkaline substance maintaining the alkaline conditions is 1:(3~5).

7. The preparation method according to claim 2, characterized in that, The method for preparing the 4,5-diaminobenzo-12-crown-4 includes: Benzo-12-crown-4 was dissolved in chloroform, concentrated nitric acid was added, and the mixture was stirred at room temperature to carry out a nitration reaction. After purification, 4,5-dinitrobenzo-12-crown-4 was obtained. The obtained 4,5-dinitrobenzo-12-crown-4 was dissolved in hydrochloric acid solution, and then placed in an ice bath with zinc powder added and stirred. After the zinc powder was completely dissolved, the ice bath was removed, and the mixture was stirred at room temperature. After the reaction was completed, alkali solution was added for neutralization. The filtrate was filtered and purified to obtain 4,5-diaminobenzo-12-crown-4.

8. The preparation method according to claim 1, characterized in that, The branched polymer crosslinking agent contains vinyl groups for polymerization.

9. The preparation method according to claim 1, characterized in that, The method for preparing the branched polymer crosslinking agent includes: Branched polyethyleneimine is heated with a substance having the structure shown in Formula III under alkaline conditions to carry out a second reaction, and the branched polymer crosslinking agent is obtained after purification. In Formula III, X is Cl or Br.

10. The preparation method according to claim 9, characterized in that, The alkaline conditions for the second reaction are pH = 10~11.

11. The preparation method according to claim 9, characterized in that, The heating temperature for the second reaction is 70~90℃.

12. The preparation method according to claim 9, characterized in that, The second reaction takes 6 to 10 hours.

13. The preparation method according to claim 9, characterized in that, The branched polyethyleneimine has an amino group content of 15-20 mmol / g.

14. The preparation method according to claim 9, characterized in that, The molar ratio of the branched polyethyleneimine to the substance having the structure shown in Formula III is 1:(1~1.1).

15. The preparation method according to claim 1, characterized in that, The preparation method includes: First, the polymer monomer, the initiator, the branched polymer crosslinking agent, and the crown ether crosslinking agent are dissolved in the lithium salt solution and stirred evenly. Then, the lithium ion sieve is added to form a suspension, and the polymerization reaction is carried out on the suspension.

16. The preparation method according to claim 15, characterized in that, The concentration of lithium salt in the lithium salt solution is 0.8~1.2 mol / L.

17. The preparation method according to claim 1, characterized in that, The mass ratio of the branched polymer crosslinking agent to the crown ether crosslinking agent is 1:(2~6).

18. The preparation method according to claim 1, characterized in that, The mass ratio of the lithium-ion sieve to the polymer monomer is 1:(0.8~1.5).

19. The preparation method according to claim 1, characterized in that, The ratio of the total mass of the branched polymer crosslinking agent and the crown ether crosslinking agent to the mass of the polymer monomer is (0.3~0.7):

1.

20. The preparation method according to claim 1, characterized in that, The ratio of the total mass of the polymeric monomer, the branched polymer crosslinking agent, and the crown ether crosslinking agent to the mass of the initiator is 1:(0.03~0.05).

21. The preparation method according to claim 1, characterized in that, The lithium-ion sieve is in a lithium-rich state.

22. The preparation method according to claim 21, characterized in that, The lithium-ion sieve in the lithium-rich state includes LiMn2O4, Li 1.5 Mn2O4, Li 1.33 Mn 1.67 O4, Li 1.6 Mn 1.6 O4, Li2TiO3, Li4Ti5O 12 At least one of them.

23. The preparation method according to claim 1, characterized in that, The polymer monomer includes at least one of acrylic acid, acrylamide, hydroxyethyl acrylate, or 2AM12C4.

24. The preparation method according to claim 1, characterized in that, The initiator includes thermal initiators and / or photoinitiators.

25. The preparation method according to claim 24, characterized in that, The thermal initiator includes at least one of azobisisobutyronitrile, azobisisoheptanenitrile, dimethyl azobisisobutyrate, benzoyl peroxide, or cumene hydroperoxide.

26. The preparation method according to claim 24, characterized in that, The photoinitiator includes at least one of benzoin dimethyl ether, 2-hydroxy-2-methyl-1-phenylpropanone, or 1-hydroxycyclohexyl ketone.

27. The preparation method according to claim 1, characterized in that, The lithium salt includes lithium chloride and / or lithium nitrate.

28. The preparation method according to claim 15, characterized in that, The lithium salt solution contains solvent A and solvent B, wherein solvent A includes methanol and / or ethanol; and solvent B includes DMSO and / or DMF.

29. The preparation method according to claim 1, characterized in that, The polymerization reaction is carried out under heating and / or ultraviolet light irradiation.

30. The preparation method according to claim 1, characterized in that, The aging temperature is 40~60℃, and the time is 6~24h.

31. The preparation method according to claim 1, characterized in that, The aging process is followed by drying, and the drying method includes freeze drying or heat drying.

32. The preparation method according to claim 1, characterized in that, The delithiation process includes acid washing.

33. A lithium-imprinted ion sieve composite material, characterized in that, The preparation method according to any one of claims 1-32 is obtained.

34. The use of the lithium-imprinted ion sieve composite material according to claim 33, characterized in that, The applications include lithium extraction from liquid lithium ore resources.

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