Lithium adsorbent material, method of making and use thereof

Abstract

The application relates to the field of adsorbing materials, and discloses a lithium adsorbing material and a preparation method and application thereof. The lithium adsorbing material comprises a skeleton and lithium ion sieve material dispersed in the skeleton, the lithium ion sieve material is connected with the skeleton through a coupling agent, and the skeleton is provided by a crosslinked or non-crosslinked polyhydroxy polymer. The method can prepare the lithium adsorbing material which has hydrophilicity, structural stability, acid and alkali resistance, a large saturated adsorption capacity for lithium, a high extraction rate and high selectivity, and is more suitable for practical application.

Description

Technical Field

[0001] This invention relates to the field of adsorption materials, specifically to a lithium adsorption material, its preparation method, and its application. Background Technology

[0002] With the rapid development of the lithium battery industry, the demand for lithium resources from various sectors is continuously increasing, and the importance of lithium production is also growing. Currently, lithium resources are mainly distributed in lithium ore and salt lake brine, but lithium ore resources are constantly decreasing, and development costs are constantly increasing; in contrast, lithium resources in salt lake brine are low-cost and abundant. my country has abundant liquid lithium resources, but extracting lithium from lithium lake brine is a challenging task.

[0003] Currently, the main methods for lithium extraction from salt lakes include adsorption, precipitation, extraction, electrodialysis, and calcination. Among these, adsorption offers advantages such as simple process, energy efficiency, and high selectivity, outperforming other methods in terms of both time and cost, and thus has broad application prospects. Since salt lake brine often suffers from low lithium content, the core of lithium extraction using adsorption is the preparation of highly selective adsorbents. Highly selective lithium adsorbents mainly include ion sieve adsorbents and amorphous hydroxide adsorbents. However, because these adsorbents are synthesized in powder form, they cannot be directly applied to conventional equipment such as fixed-bed adsorption-desorption systems for lithium extraction. Currently, lithium adsorbents are also granulated to obtain granular lithium adsorbent materials. Common granulation methods include: (1) using inorganic binders such as alumina and silica gel for granulation. This method is simple to prepare granular adsorbents, but the stability is poor. It is often used in conjunction with polymer granulation methods. (2) using natural polymer materials such as chitosan and sodium alginate for granulation. However, the products prepared by this method have poor long-term performance stability. (3) using organic polymer materials such as PU, PAM, and PVC as binders for granulation. However, the prepared granular adsorbents have poor hydrophilicity and are prone to encapsulation of powder adsorbents, which leads to a significant decrease in adsorption capacity.

[0004] Most existing methods involve physically blending polymers with lithium-ion adsorbents, followed by cross-linking with aldehydes such as glutaraldehyde, and then granulation. However, granules prepared by this method exhibit poor stability during long-term use, are prone to detachment from the ion sieve powder, and suffer from poor dispersibility. Furthermore, due to the unique structural characteristics of titanium-based and manganese-based lithium-ion sieves, their adsorption capacity under alkaline conditions is higher than under neutral or acidic conditions, and their desorption efficiency under acidic conditions is higher than under neutral or alkaline conditions. Therefore, industrial processes require granulated products to have a certain degree of tolerance to acidic or alkaline solutions. In conclusion, developing acid- and alkali-resistant granulation technology for lithium adsorbent powder materials is of great significance for the future development of lithium resources. Summary of the Invention

[0005] The purpose of this invention is to overcome the aforementioned problems in the prior art and provide a lithium adsorbent material, its preparation method, and its application. This method can prepare lithium adsorbent particles that are hydrophilic, structurally stable, acid and alkali resistant, and have a high lithium adsorption capacity, making them more suitable for practical applications.

[0006] To achieve the above objectives, the first aspect of the present invention provides a lithium adsorbent material comprising a framework and a lithium ion sieve material dispersed in the framework, wherein the lithium ion sieve material is connected to the framework by a coupling agent, and the framework is provided by a cross-linked or uncross-linked polyhydroxy polymer.

[0007] A second aspect of the present invention provides a method for preparing lithium adsorbent materials, the method comprising:

[0008] In the presence of a coupling agent, a polyhydroxy polymer and a lithium-ion sieve material are coupled together.

[0009] Thirdly, the present invention provides a lithium adsorbent material prepared by the method described above.

[0010] Fourthly, the present invention provides the application of the lithium adsorbent material described above in lithium extraction from salt lakes.

[0011] The method and lithium adsorbent material products provided by this invention facilitate the long-term stable adsorption performance of lithium ion sieves (especially manganese-based and titanium-based lithium ion sieve materials) in adsorption processes, enabling long-term adsorption under alkaline conditions and desorption under acidic conditions. For manganese-based and titanium-based lithium ion sieve material powders, lithium ion sieve precursors can be directly used for granulation, thus eliminating the need for acid washing of the precursor powder. Most importantly, the obtained product exhibits a large saturated adsorption capacity for lithium, high extraction rate, and strong selectivity. This method is simple to prepare, environmentally friendly, and solvent-free, possessing broad industrialization prospects.

[0012] In particular, the lithium-ion sieve material modified with polyphenols has a large number of hydroxyl groups on its surface, which have better compatibility with the polyhydroxy polymer skeleton and are easier to disperse uniformly in the skeleton. Therefore, a large amount of lithium-ion sieve material can be loaded in the skeleton. In addition, the hydroxyl groups on the surface of the polyphenol-modified lithium-ion sieve material can further bond with the coupling agent. The bonding between the polyphenol-modified lithium-ion sieve material and the skeleton can further ensure that the powder will not aggregate or be lost during long-term scouring by water flow and pressure. The granulated product has high strength and good toughness and is not easy to break or pulverize when loaded into the adsorption tower. Especially under the combined action of silane coupling agent and polyphenol-modified lithium-ion sieve material, the lithium adsorbent material loaded with polyphenol-modified lithium-ion sieve material has the following advantages: (1) large network structure, porosity and specific surface area; (2) due to the excellent hydrophilicity of polyhydroxy polymers, the adsorption kinetics of lithium ions in aqueous solution is fast and it is easy to reach the theoretical maximum adsorption capacity of the lithium-ion sieve addition amount; (3) stable under acid and alkaline conditions. Attached Figure Description

[0013] Figure 1 This is the product of Example 1, and the modified Li after step (1) of Example 1. 1.33 Mn 1.67 O4, and the infrared spectrum of polyvinyl alcohol used in Example 1;

[0014] Figure 2 The product of Example 1 and the modified Li 1.33 Mn 1.67 XRD pattern of O4;

[0015] Figure 3 This is an SEM (scanning electron microscope) image of the product from Example 1;

[0016] Figure 4 This is a physical image of the product from Example 1. Detailed Implementation

[0017] 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.

[0018] In a first aspect, the present invention provides a lithium adsorbent material comprising a framework and a lithium ion sieve material dispersed in the framework, wherein the lithium ion sieve material is connected to the framework by a coupling agent, and the framework is provided by a cross-linked or uncross-linked polyhydroxy polymer.

[0019] According to the present invention, preferably, the average particle size of the lithium adsorbent material is 1-5 mm, more preferably 2-4 mm.

[0020] Preferably, the mass content of the lithium-ion sieve material is 10-80 wt% relative to the mass of the lithium adsorbent material, more preferably 68-77 wt% (for example, it can be 68 wt%, 69 wt%, 70 wt%, 71 wt%, 72 wt%, 73 wt%, 74 wt%, 75 wt%, 76 wt%, 77 wt%, and any two of the above values ​​within the range and values ​​within the range).

[0021] Preferably, the specific surface area of ​​the lithium adsorbent material is 10-500 m². 2 / g, more preferably 10-45m 2 / g (for example, it can be 10m) 2 / g, 15m 2 / g、20m 2 / g、25m 2 / g、30m 2 / g、35m 2 / g、40m 2 / g、45m 2 / g and the range formed by any two of the above values, and the values ​​within that range).

[0022] Preferably, the average pore size of the lithium adsorbent material is 0.1-10 μm, more preferably 2-5 μm (for example, it can be 2 μm, 3 μm, 4 μm, 5 μm, or any two of the above values ​​within a range).

[0023] Preferably, the pore volume of the lithium adsorbent material is 10-100 μm. 3 / g, more preferably 50-85m 3 / g (for example, 50m) 3 / g、55m 3 / g、60m 3 / g、65m 3 / g、70m 3 / g、75m 3 / g、80m 3 / g、85m 3 / g and the range formed by any two of the above values, and the values ​​within that range).

[0024] Preferably, at 25°C, the lithium adsorbent material has a water absorption rate of 0.1-2 g / g for pure water and a volume swelling rate of 2-10% (for example, it can be 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, or any two of the above values ​​within a range).

[0025] According to the present invention, preferably, the lithium-ion sieve material is selected from titanium-based and / or manganese-based lithium-ion sieve materials.

[0026] Preferably, the average particle size of the lithium-ion sieve material is 10-500 μm (for example, it can be 10 μm, 50 μm, 100 μm, 200 μm, 300 μm, 400 μm, 500 μm, or any two of the above values ​​within a range).

[0027] Preferably, the polyhydroxy polymer is selected from at least one of polyvinyl alcohol, chitosan, polyethylene glycol and carboxymethyl cellulose, and more preferably polyvinyl alcohol.

[0028] Preferably, the coupling agent is selected from silane coupling agents.

[0029] Preferably, the silane coupling agent is selected from at least one of mercapto-containing silane coupling agents and epoxy-containing silane coupling agents, and is more preferably an epoxy-containing silane coupling agent.

[0030] More preferably, the epoxy-containing silane coupling agent is selected from at least one of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-(2,3-epoxypropoxypropyl)methyldiethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane.

[0031] According to the present invention, preferably, the lithium-ion sieve material is a lithium-ion sieve material modified with polyphenols.

[0032] Preferably, the method for polyphenol modification includes: mixing lithium ion sieve material and polyphenol to modify the lithium ion sieve material.

[0033] Preferably, the mixing is carried out in a solution environment.

[0034] Preferably, the mass ratio of lithium ion sieve material to polyphenol is 1:(0.08-0.3).

[0035] Preferably, the mixing time is 1-3 hours.

[0036] The polyphenol is selected from at least one of tannic acid, tea polyphenols, dopamine, sennaol, epicatechin, luteolin, calciferol, myricetin and genistein, preferably at least one of tannic acid, tea polyphenols and dopamine.

[0037] Secondly, the present invention provides a method for preparing lithium adsorbent materials, the method comprising:

[0038] In the presence of a coupling agent, a polyhydroxy polymer and a lithium-ion sieve material are coupled together.

[0039] It is understood that lithium-ion sieve materials refer to materials with lithium adsorption capabilities. When applied for adsorption, hydrogen ions and lithium ions in the lithium-ion sieve material exchange, thereby enriching the lithium ions onto the lithium adsorbent material. When preparing lithium adsorbent materials using lithium-ion sieve materials, the lithium-ion sieve material can be a lithium-ion sieve rich in hydrogen ions; or it can be a lithium-ion sieve precursor with a lower hydrogen ion content but a higher lithium ion content. Before application for adsorption, it is acid-washed to replace the lithium ions with hydrogen ions, thus obtaining the lithium-ion sieve. That is, the lithium-ion sieve material described in this application includes both lithium-ion sieves and lithium-ion sieve precursors.

[0040] The inventors of this invention discovered in their research that the lithium adsorbent material prepared using the above method exhibits a large saturated adsorption capacity, high extraction rate, and high selectivity for lithium. Specifically, the polyhydroxy polymer is hydrophilic, possesses a network structure in its framework, and has high porosity and specific surface area, resulting in a high adsorbent loading; this is beneficial for improving the adsorption rate and amount of lithium. After coupling, the compatibility between the polyhydroxy polymer and the lithium-ion sieve material is also better; the lithium-ion sieve material is less prone to agglomeration and is more uniformly distributed on the polyhydroxy polymer, which is more conducive to the adsorption effect.

[0041] The specific type of coupling agent is not particularly limited, as long as it can simultaneously connect the polyhydroxy polymer and the lithium-ion sieve material. However, preferably, the coupling agent is selected from silane coupling agents. Silane coupling agents generally have a YR-Si-X3 structure, where Y is an organic functional group, R is an alkylene group, and X is an alkoxy group. The alkoxy group can be hydrolyzed to obtain a hydroxyl group, thereby reacting with inorganic substances such as lithium-ion sieve materials; the organic functional group can react with organic substances such as polyvinyl alcohol.

[0042] According to the present invention, preferably, the silane coupling agent is selected from at least one of thiol-containing silane coupling agents and epoxy-containing silane coupling agents, and more preferably an epoxy-containing silane coupling agent. It is understood that thiol and epoxy groups refer to the groups contained in the YR structure of the silane coupling agent.

[0043] According to the present invention, more preferably, the epoxy-containing silane coupling agent is selected from at least one of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-(2,3-epoxypropoxypropyl)methyldiethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane. Thiol-containing silane coupling agents include γ-mercaptopropyltriethoxysilane, etc.

[0044] According to the present invention, preferably, the polyhydroxy polymer is selected from at least one of polyvinyl alcohol, chitosan, polyethylene glycol, and carboxymethyl cellulose, more preferably polyvinyl alcohol. The weight-average molecular weight of the polyhydroxy polymer is not particularly limited, for example, it can be 50,000-250,000 g / mol. The degree of alcoholysis of the polyvinyl alcohol can be 83-99%.

[0045] According to the present invention, preferably, the lithium-ion sieve material is selected from titanium-based and / or manganese-based lithium-ion sieve materials. For example, it can be LiMn2O4, Li... 1.6 Mn 1.6 O4, Li 1.33 Mn 1.67 O4, Li4Mn5O 12 , LiMnO, LiMnO2, Li2TiO3, Li 1.33 Ti 1.66 O4, Li4Ti5O 12 Such lithium-ion sieve precursors, or their corresponding acid-washed lithium-ion sieves.

[0046] According to the present invention, preferably, the average particle size of the lithium-ion sieve material is 10-500 μm (for example, it can be 10 μm, 50 μm, 100 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 500 μm, or any value within the range formed by any two of the above values). During preparation, the lithium-ion sieve material in powder form within the above particle size range can be used.

[0047] The aforementioned lithium-ion sieve materials can be obtained by purchase or prepared by the manufacturer. The preparation method can be a conventional method in the field. Taking the high-temperature solid-phase synthesis preparation method of Li2TiO3 as an example: anatase TiO2 and Li2CO3 (both referred to as solids) can be weighed at a molar ratio of 1:1-1.2 and added to a stainless steel ball mill jar. Then, ethanol equivalent to 1.8-2.2 times the mass of the solids and stainless steel beads (with a diameter of 3-5 mm) equivalent to 18-25 times the mass of the solids are added to the ball mill jar. The mixture is ball-milled at a speed of 180-220 rpm for 3.5-4.5 h using a planetary ball mill. After drying at 35-45℃, the mixture is placed in a muffle furnace and calcined in an air atmosphere at 750-850℃ for 5-7 h. After cooling, the mixture is eluted with 0.4-0.6 mol / L HCl solution for 18-28 h to obtain lithium-ion adsorbent powder Li2TiO3.

[0048] According to the present invention, preferably, prior to coupling, the method further includes: mixing the lithium-ion sieve material with polyphenols to modify the lithium-ion sieve material.

[0049] According to the present invention, preferably, the mixing is carried out in a solution environment. For example, it can be carried out in an aqueous solution environment of polyphenols.

[0050] Preferably, the mass ratio of lithium-ion sieve material to polyphenol is 1:(0.08-0.3). In the aqueous solution, the concentration of polyphenol can be 0.1-1 mg / L.

[0051] Preferably, the mixing time is 1-3 hours. During mixing, stirring can be performed (at a speed of 300-500 rpm), and the mixing can be carried out at room temperature.

[0052] Preferably, the polyphenol is selected from at least one of tannic acid, tea polyphenols, dopamine, sennaol, epicatechin, luteolin, calciferol, myricetin and genistein, and more preferably at least one of tannic acid, tea polyphenols and dopamine.

[0053] The above modifications generally enable the formation of a polyphenol modified layer of about 0.1-2 nm on the surface of the lithium ion screen material, resulting in a large number of hydroxyl groups on the surface of the lithium ion screen material. This leads to better compatibility with the polyhydroxy polymer skeleton and easier uniform dispersion in the skeleton, further ensuring that the lithium ion screen material will not accumulate or be lost during long-term scouring by water flow and pressure.

[0054] After mixing and stirring, the material can be separated into solid and liquid phases (e.g., by centrifugation), and the resulting solid material can be dried (at a temperature of 30-80℃ for 4-12 hours).

[0055] Using the above method, a 10-50 nm polyphenol modification layer can generally be formed on the surface of lithium-ion sieve materials. Understandably, the particle size of the lithium-ion sieve materials does not change significantly before and after modification.

[0056] According to the present invention, preferably, the mass ratio of the polyhydroxy polymer, the lithium-ion sieve material, and the coupling agent is 1:(0.1-5):(0.05-1.5), more preferably 1:(3-5):(0.1-1.5). This allows for a more uniform and efficient loading of the lithium-ion sieve powder material onto the polyvinyl alcohol framework.

[0057] According to the present invention, the preferred coupling conditions include: a temperature of 50-90°C (e.g., 50°C, 60°C, 70°C, 80°C, 90°C), a time of 1-24 hours (e.g., 1 hour, 3 hours, 5 hours, 8 hours, 10 hours, 12 hours, 15 hours, 18 hours, 20 hours, 22 hours, 24 hours), and a pH of 1-3 (e.g., 1, 1.5, 2, 2.5, 3). The pH can be adjusted using hydrochloric acid.

[0058] In use, polyhydroxy polymers are generally used in the form of aqueous solutions, with a concentration of 8-16 wt% in the aqueous solution.

[0059] Preferably, after coupling, the method further includes: aging and granulating the material sequentially.

[0060] Preferably, the aging conditions include a temperature of 50-70°C and a time of 0.2-2 hours.

[0061] Preferably, granulation is performed to achieve a material particle size of 1-5 mm, more preferably 2-4 mm. This can be carried out in a granulator. The particle size of the granulated material may not be completely uniform, but rather fall within a range.

[0062] According to the present invention, preferably, the method further includes: cross-linking the granulated product under the action of a cross-linking agent. It is understood that the cross-linking agent causes the backbone of the lithium adsorbent material, i.e., the polyhydroxy polymer, to cross-link.

[0063] According to the present invention, preferably, the crosslinking method is as follows: immersing the granulated product in a crosslinking agent solution with a concentration of 0.1-1 wt% (e.g., 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, or 1 wt%), at a crosslinking temperature of 20-40°C (e.g., 20°C, 25°C, 30°C, 35°C, or 40°C), and for a crosslinking time of 30-120 min (e.g., 30 min, 40 min, 50 min, 60 min, 70 min, 80 min, 90 min, 100 min, 110 min, or 120 min). Generally, the amount of crosslinking agent solution relative to 1 g of granulated product can be 80-150 ml.

[0064] After re-coupling, the above cross-linking process is carried out, resulting in a stronger bond between the polyhydroxy polymer and the lithium ion sieve material, a more stable structure, and a more acid and alkali resistant lithium adsorbent material.

[0065] According to the present invention, preferably, the crosslinking agent is selected from at least one aldehyde compound, and more preferably from at least one of C1-C5 monoaldehydes and C1-C5 dialdehydes. It is understood that the particle size of the material does not change significantly before and after crosslinking. The aldehyde group in the crosslinking agent can undergo an aldol condensation reaction with the hydroxyl group in the polyhydroxy polymer to form a crosslinked polyhydroxy polymer structure.

[0066] According to the present invention, preferably, the method further includes: acid washing of the crosslinked product after crosslinking. Before acid washing, the material can be dried (or oven-dried) at 50-70°C for 18-36 hours, and then circulated and acid-washed in an adsorption column using 0.05-0.3 mol / L hydrochloric acid for 0.5-2 hours. The acid-washed material can be circulated once more with deionized water for washing. Acid washing can replace lithium ions on the lithium-ion sieve material with hydrogen ions.

[0067] Thirdly, the present invention provides a lithium adsorbent material prepared by the method described above.

[0068] Preferably, the average particle size of the lithium adsorbent material is 1-5 mm, more preferably 2-4 mm.

[0069] Fourthly, the present invention provides the application of the lithium adsorbent material described above in lithium extraction from salt lakes.

[0070] One method for applying the aforementioned lithium adsorbent material to lithium-containing solutions (such as salt lakes) is as follows: The lithium adsorbent material is mixed with brine containing lithium ions for adsorption. The brine generally also contains magnesium ions, and the lithium ion concentration in the brine can be 10-800 ppm, while the total lithium ion concentration can be 1000-4000 ppm. The pH of the brine can be 8.8-11.2. The amount of lithium adsorbent material used is 0.3-1 g per 40 ml of brine.

[0071] The present invention will be described in detail below through embodiments.

[0072] In the following embodiments, the method for drying, acid washing, and water washing of the cross-linked material is as follows: the cross-linked material is dried in an oven at 60°C for 24 hours, then the material is loaded into an adsorption column and circulated in the column with 0.1 mol / L HCl for 1 hour. The acid-washed material is then circulated with deionized water once and washed with water.

[0073] Example 1

[0074] (1) Take powder Li 1.33 Mn 1.67 O4 (average particle size 300 μm) was mixed with an aqueous solution of tannic acid (tannic acid concentration 0.1 mg / L) to make the mass ratio of lithium ion sieve material to polyphenol 1:0.1. The mixture was stirred at room temperature for 2 h (300 rpm), then centrifuged and the solid phase material was dried (temperature 60℃, time 8 h) to complete the modification of lithium ion sieve material.

[0075] (2) Take a 15wt% polyvinyl alcohol aqueous solution (degree of alcoholysis 88%, weight average molecular weight 89000 g / mol) and the modified Li prepared in step (1).1.33 Mn 1.67 O4 powder was mixed and stirred evenly, and γ-(2,3-epoxypropoxy)propyltrimethoxysilane was added to make polyvinyl alcohol: modified Li 1.33 Mn 1.67 The mass ratio of O4 to γ-(2,3-epoxypropoxy)propyltrimethoxysilane was 1:5:1.5, and the pH of the system was adjusted to 1 with 0.1 mol / L HCl. The mixture was stirred at 70°C for 8 hours and then aged in a 60°C oven for 30 minutes to obtain a semi-solid product. This product was then extruded to obtain a material with a particle size of 2-3 mm.

[0076] (3) The material obtained in step (2) is immersed in a formaldehyde aqueous solution with a formaldehyde concentration of 0.1wt% at 20°C for 120 minutes to carry out cross-linking.

[0077] The cross-linked material is dried, acid-washed, and water-washed to obtain the product as follows: Figure 4 As shown.

[0078] Example 2

[0079] (1) Take powder Li 1.33 Mn 1.67 O4 (average particle size 250 μm) was mixed with an aqueous solution of tannic acid (tannic acid concentration 0.5 mg / L) to make the mass ratio of lithium ion sieve material to polyphenol 1:0.3. The mixture was stirred at room temperature for 1 h (400 rpm), then centrifuged and the solid phase material was dried (temperature 60℃, time 8 h) to complete the modification of lithium ion sieve material.

[0080] (2) Take a 13wt% polyvinyl alcohol aqueous solution (degree of alcoholysis 88%, weight average molecular weight 89000 g / mol) and the modified Li prepared in step (1). 1.33 Mn 1.67 O4 powder was mixed and stirred evenly, and γ-(2,3-epoxypropoxy)propyltrimethoxysilane was added to make polyvinyl alcohol: modified Li 1.33 Mn 1.67 The mass ratio of O4 to γ-(2,3-epoxypropoxy)propyltrimethoxysilane was 1:3:0.8, and the pH of the system was adjusted to 2 with 0.1 mol / L HCl. The mixture was stirred at 50 °C for 24 h and then aged in an oven at 55 °C for 60 min to obtain a semi-solid product. The product was then extruded to obtain a material with a particle size of 2-3 mm.

[0081] (3) The material obtained in step (2) is immersed in a formaldehyde aqueous solution with a formaldehyde concentration of 1 wt% at 30°C (the amount of crosslinking agent solution is 100 ml relative to 1 g of granulated product) for 30 min to carry out crosslinking.

[0082] Example 3

[0083] (1) Take powder Li 1.33 Mn 1.67 O4 (average particle size 350 μm) was mixed with an aqueous solution of tannic acid (tannic acid concentration 1 mg / L) to make the mass ratio of lithium ion sieve material to polyphenol 1:0.08. The mixture was stirred at room temperature for 3 h (500 rpm), then centrifuged and the solid phase material was dried (temperature 60℃, time 8 h) to complete the modification of lithium ion sieve material.

[0084] (2) Take a 10wt% polyvinyl alcohol aqueous solution (degree of alcoholysis 88%, weight average molecular weight 89000 g / mol) and the modified Li prepared in step (1). 1.33 Mn 1.67 O4 powder was mixed and stirred evenly, and γ-(2,3-epoxypropoxy)propyltrimethoxysilane was added to make polyvinyl alcohol: modified Li 1.33 Mn 1.67 The mass ratio of O4 to γ-(2,3-epoxypropoxy)propyltrimethoxysilane was 1:3.5:0.1, and the pH of the system was adjusted to 3 with 0.1 mol / L HCl. The mixture was stirred at 90 °C for 1 h and then aged in a 70 °C oven for 120 min to obtain a semi-solid product. The product was then extruded to obtain a material with a particle size of 2-3 mm.

[0085] (3) The material obtained in step (2) is immersed in a formaldehyde aqueous solution with a formaldehyde concentration of 0.8wt% at 38°C for 80 minutes to carry out cross-linking.

[0086] Example 4

[0087] The method of Example 1 is followed, except that in step (1), tannic acid is replaced with tea polyphenols.

[0088] Example 5

[0089] The procedure was carried out according to Example 1, except that in step (1), tannic acid was replaced with dopamine.

[0090] Example 6

[0091] The procedure was carried out according to Example 1, except that the coupling agent was replaced with γ-mercaptopropyltriethoxysilane.

[0092] Example 7

[0093] The method of Example 1 was followed, except that in step (2), the coupling agent was replaced with 3-aminopropyltrimethoxysilane.

[0094] Example 8

[0095] The lithium adsorbent material was prepared according to the method of Example 1, except that the modification in step (1) was not performed.

[0096] Comparative Example 1

[0097] The lithium adsorbent material was prepared according to the method of Example 1, except that in step (2), γ-(2,3-epoxypropoxy)propyltrimethoxysilane was replaced with glutaraldehyde, and step (3) was not performed.

[0098] Comparative Example 2

[0099] The lithium adsorbent material was prepared according to the method of Example 1, except that the powder modification in step (1) was not performed; and in step (2), γ-(2,3-epoxypropoxy)propyltrimethoxysilane was replaced with glutaraldehyde.

[0100] Comparative Example 3

[0101] The lithium adsorbent material was prepared according to the method of Example 1, except that no coupling agent was used in step (2).

[0102] Comparative Example 4

[0103] The lithium adsorbent material was prepared according to the method of Example 1, except that polyvinyl alcohol was not added in step (2) (that is, the polyvinyl alcohol aqueous solution in Example 1 was replaced with the same weight of water).

[0104] Test case

[0105] The lithium adsorbent materials prepared in the above examples and comparative examples were subjected to the following measurements:

[0106] Adsorption capacity determination:

[0107] Take 0.5g of lithium adsorbent material and 40ml of lithium-magnesium mixed solution (Li + The concentration is 100 ppm, Mg 2+ Static adsorption was performed using a mixed solution of lithium chloride and magnesium chloride (2000 ppm, pH 10.0, alkaline conditions). The change in adsorption capacity over time during the adsorption process was monitored, resulting in the kinetic curve (adsorption capacity - adsorption time). Adsorption kinetics reflects the rate of adsorption by the adsorbent.

[0108] After static adsorption for 24 hours, solid-liquid separation was performed, and the saturated adsorption capacity Q was calculated according to the following formula. Then, desorption was carried out with 0.5M HCl for 24 hours.

[0109]

[0110] Where Q is the saturated adsorption capacity in mg / g, reflecting the amount of adsorption at equilibrium; C0 and C are the initial and saturated ion concentrations in the solution, respectively, in mg / L; V is the volume of the adsorption solution in L; and M is the mass of the particulate adsorbent in g. Ion concentrations were determined using ion chromatography (ICS-1100, DIONEX, America).

[0111] Lithium extraction efficiency is the ratio of the mass of lithium adsorbed by the adsorbent to the mass of lithium in the solution.

[0112] Selectivity coefficient This refers to the preference of an adsorbent for ions A when adsorbing two ions, A and B. A higher value indicates better selectivity for ions A, reflecting the adsorbent's selectivity for different ions. The partition coefficient (K) represents the ratio of the two ions. d The ratio of ).

[0113]

[0114]

[0115] In the above formula, C0 is the concentration of each ion in the solution before adsorption, mg / L; C is the concentration of each ion when adsorption is saturated, mg / L; V is the solution volume, mL; and m is the mass of the adsorbent, g.

[0116] The stability of the lithium adsorbent material for recycling was characterized using dynamic adsorption. The specific method was as follows: At 40℃, the lithium adsorbent material was packed into an adsorption column with a column volume of one fluidized bed (1 BV). Dynamic adsorption was performed, with 8 BV of brine injected and passed through the granules at a flow rate of 3 BV / h. After adsorption, desorption was performed using 2 BV of desorption solution, passed through the granules at a flow rate of 1-8 BV / h. The pH of the injected brine was 12, and the pH of the desorption solution was 3.

[0117] Table 1

[0118]

[0119] The inventors of this invention also discovered that after 40 cycles of alkaline adsorption and acid washing to desorb the products of Examples 1-6, the adsorption capacity of the products did not change significantly, and the mass loss ratio was less than 1%, indicating that the products prepared by the scheme of this invention have a stable structure and good acid resistance. In contrast, the mass loss ratio of Comparative Examples 1-2 was 2-5%. Furthermore, hardness tests using a Shore A hardness tester revealed that the Shore A hardness of the products of Examples 1-6 was 60-70, while the Shore A hardness of the products of Comparative Examples 1-2 was less than 20. The particles of Comparative Examples 1-2 were brittle and easily broken in the dry state, the particles of Comparative Example 3 had a loose structure and were difficult to form, and the particles of Comparative Example 4 disintegrated upon dissolving in water, making the above tests impossible. These results demonstrate that the granulated products have a stable structure and the powder is not easily detached after long-term use.

[0120] The inventors of this invention also discovered that the products of Examples 1-6 achieve adsorption equilibrium within 4 hours, and reach 90% adsorption capacity within 30 minutes. The products provided by this invention have strong hydrophilicity, excellent water permeability, and can rapidly exchange water and ions.

[0121] Test Example 2

[0122] The product of Example 1 and the Li modified in step (1) of Example 1 1.33 Mn 1.67 O4 and the polyvinyl alcohol used in Example 1 were characterized by infrared spectroscopy using a Fourier transform infrared spectrometer (FT-IR, MAGNA-IR 550). The results are shown in [Figure 1]. Figure 1 .

[0123] Figure 1 It can be seen that the absorption peak of the tannic acid-modified lithium-ion sieve material is at 3400 cm⁻¹. -1 The hydroxyl peak appeared at 1637 cm⁻¹ -1 The appearance of the C=C peak indicates successful polyphenol modification. The IR peak of polyvinyl alcohol (PVA) at 3400 cm⁻¹... -1 The large peak is the -OH peak, at 1733 cm⁻¹. -1 2927cm -1 The peak represents the stretching vibration of -C=C. The IR absorption peak of the product in Example 1 is at 2927 cm⁻¹. -1 3400cm -1 The peak (3400 cm⁻¹) of the tannic acid-modified lithium-ion sieve material was observed. -1 The C=C characteristic peak of PVA (2927 cm⁻¹) and PVA -1 ), and 1197cm -1The nearby characteristic peaks are characteristic peaks of Si-O-C, indicating that the coupling agent in the product of Example 1 successfully coupled PVA and polyphenol-modified lithium-ion sieve material. Infrared characterization also revealed that the coupling agent in the products of Examples 1-8 also successfully coupled PVA and polyphenol-modified lithium-ion sieve material.

[0124] The product of Example 1 and the modified Li 1.33 Mn 1.67 The XRD pattern of O4 is shown below. Figure 2 It can be observed that the characteristic peaks and peak spacing of the product in Example 1 are similar to those of Li. 1.33 Mn 1.67 The O4 powder was basically similar and showed no significant changes, indicating that the prepared product did not affect the composition of the lithium-ion sieve material. The corresponding situations in Examples 1-6 were similar to those in the Examples.

[0125] The products prepared in Examples 1-6 have good powder dispersibility. Taking the product of Example 1 as an example, the results were obtained by scanning electron microscopy (SEM, S-4800) (see the results of Example 1 for details). Figure 3 Electron microscopy reveals an irregular porous structure within the particles, with pore sizes ranging from 2 to 5 μm. The powdered adsorbent is relatively uniformly dispersed and embedded within this microporous network framework. This structure prevents powder leakage during long-term use, thereby ensuring the product's strength and stability, and preventing significant changes in performance over extended periods. This demonstrates that polyphenol modification increases compatibility and improves the dispersibility of lithium-ion sieve materials on the product.

[0126] Test Example 3

[0127] The lithium adsorbent materials prepared in the above examples and comparative examples were subjected to the following measurements:

[0128] The specific surface area and pore volume were determined by measuring the adsorption-desorption isotherm of N2 on the lithium adsorbent material at 77 K and fitting the data to obtain the BET specific surface area and pore volume.

[0129] The average aperture was determined by scanning electron microscopy.

[0130] The water absorption rate A and volume swelling rate P were determined by placing a lithium adsorbent material with a mass of W0 and a volume of V0 in sufficient distilled water at 25℃. After 24 hours, the weight W1 and volume V1 were measured. A = (W1-W0) / W0, unit g / g; P = (V1-V0) / V0.

[0131] The method for determining the mass content of lithium-ion sieve materials and framework relative to the mass of lithium adsorbent materials is as follows:

[0132] For the products of Examples 1-8, the contents of Mn, Si, C, and O elements were determined by X-ray photoelectron spectroscopy (XPS). The mass of the lithium-ion sieve was calculated based on the Mn content, the mass of the coupling agent was calculated based on the Si content, and the remaining part was the mass of the framework. For the products of Comparative Examples 1-2, the Mn content was determined by X-ray photoelectron spectroscopy (XPS). The mass of the lithium-ion sieve was calculated based on the Mn content, and the remaining part was the mass of the framework.

[0133] The results are shown in Table 2-3.

[0134] Table 2

[0135]

[0136]

[0137] Table 3

[0138]

[0139] In Examples 4-7, the lithium-ion sieve material has a mass content of 71-72.5 wt%, and the skeleton has a mass content of 14-15 wt%.

[0140] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A lithium adsorbent material, characterized in that, The lithium adsorbent material includes a framework and a lithium ion sieve material dispersed in the framework. The lithium ion sieve material is connected to the framework by a coupling agent. The framework is provided by a cross-linked or uncross-linked polyhydroxy polymer. The lithium-ion sieve material is a lithium-ion sieve material modified with polyphenols.

2. The lithium adsorbent material according to claim 1, wherein, The average particle size of the lithium adsorbent material is 1-5 mm; And / or, the mass content of the lithium-ion sieve material is 10-80 wt% relative to the mass of the lithium adsorbent material; And / or, the specific surface area of ​​the lithium adsorbent material is 10-500 m². 2 / g; And / or, the average pore size of the lithium adsorbent material is 0.1-10 μm; And / or, the pore volume of the lithium adsorbent material is 10-100 m³. 3 / g; And / or, at 25°C, the lithium adsorbent material has a water absorption rate of 0.1-2 g / g for pure water and a volume swelling rate of 2-10%.

3. The lithium adsorbent material according to claim 2, wherein, The average particle size of the lithium adsorbent material is 2-4 mm; And / or, relative to the mass of the lithium adsorbent material, the mass content of the lithium ion sieve material is 68-77 wt%; And / or, the specific surface area of ​​the lithium adsorbent material is 10-45 m². 2 / g; And / or, the average pore size of the lithium adsorbent material is 2-5 μm; And / or, the pore volume of the lithium adsorbent material is 50-85 m³. 3 / g.

4. The lithium adsorbent material according to claim 1, wherein, The lithium-ion sieve material is selected from titanium-based and / or manganese-based lithium-ion sieve materials; And / or, the average particle size of the lithium-ion sieve material is 10-500 μm; And / or, the polyhydroxy polymer is selected from at least one of polyvinyl alcohol, chitosan, polyethylene glycol and carboxymethyl cellulose; And / or, the coupling agent is selected from silane coupling agents.

5. The lithium adsorbent material according to claim 4, wherein, The polyhydroxy polymer is polyvinyl alcohol.

6. The lithium adsorbent material according to claim 4, wherein, The silane coupling agent is selected from at least one of thiol-containing silane coupling agents and epoxy-containing silane coupling agents.

7. The lithium adsorbent material according to claim 6, wherein, The silane coupling agent is an epoxy-containing silane coupling agent.

8. The lithium adsorbent material according to claim 7, wherein, The epoxy-containing silane coupling agent is selected from at least one of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-(2,3-epoxypropoxypropyl)methyldiethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane.

9. The lithium adsorbent material according to claim 1, wherein, The method for polyphenol modification includes: mixing lithium ion sieve material with polyphenols to modify the lithium ion sieve material.

10. The lithium adsorbent material according to claim 9, wherein, The mixing takes place in a solution environment.

11. The lithium adsorbent material according to claim 9, wherein, The mass ratio of lithium-ion sieve material to polyphenol is 1:(0.08-0.3).

12. The lithium adsorbent material according to claim 9, wherein, The mixing time is 1-3 hours.

13. The lithium adsorbent material according to claim 9, wherein, The polyphenols are selected from at least one of tannic acid, tea polyphenols, dopamine, sennaol, epicatechin, luteolin, calciferol, myricetin and genistein.

14. The lithium adsorbent material according to claim 13, wherein, Polyphenols are at least one of tannic acid, tea polyphenols, and dopamine.

15. A method for preparing lithium adsorbent materials, characterized in that, The method includes: In the presence of a coupling agent, a polyhydroxy polymer and a lithium-ion sieve material are coupled together; Prior to coupling, the method further includes: mixing the lithium-ion sieve material with polyphenols to modify the lithium-ion sieve material.

16. The method according to claim 15, wherein, The coupling agent is selected from silane coupling agents.

17. The method according to claim 16, wherein, The silane coupling agent is selected from at least one of thiol-containing silane coupling agents and epoxy-containing silane coupling agents.

18. The method according to claim 17, wherein, The silane coupling agent is an epoxy-containing silane coupling agent.

19. The method according to claim 18, wherein, The epoxy-containing silane coupling agent is selected from at least one of γ-(2,3-epoxypropoxy)propyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-(2,3-epoxypropoxypropyl)methyldiethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane.

20. The method according to any one of claims 15-19, wherein, The polyhydroxy polymer is selected from at least one of polyvinyl alcohol, chitosan, polyethylene glycol, and carboxymethyl cellulose.

21. The method according to claim 20, wherein, The polyhydroxy polymer is polyvinyl alcohol.

22. The method according to claim 15, wherein, The lithium-ion sieve material is selected from titanium-based and / or manganese-based lithium-ion sieve materials; And / or, the average particle size of the lithium-ion sieve material is 10-500 μm.

23. The method according to claim 15, wherein, The mixing takes place in a solution environment.

24. The method according to claim 23, wherein, The mass ratio of lithium-ion sieve material to polyphenol is 1:(0.08-0.3).

25. The method according to claim 23, wherein, The mixing time is 1-3 hours.

26. The method according to claim 15, wherein, The polyphenols are selected from at least one of tannic acid, tea polyphenols, dopamine, sennaol, epicatechin, luteolin, calciferol, myricetin and genistein.

27. The method according to claim 26, wherein, Polyphenols are at least one of tannic acid, tea polyphenols, and dopamine.

28. The method according to claim 15, wherein, The mass ratio of the polyhydroxy polymer, lithium-ion sieve material, and coupling agent is 1:(0.1-5):(0.05-1.5).

29. The method according to claim 28, wherein, The mass ratio of the polyhydroxy polymer, lithium-ion sieve material, and coupling agent is 1:(3-5):(0.1-1.5).

30. The method according to claim 15, wherein, The coupling conditions include: temperature of 50-90℃, time of 1-24h, and pH of 1-3; And / or, after coupling, the method further includes: aging and granulating the material sequentially.

31. The method according to claim 30, wherein, The aging conditions include a temperature of 50-70℃ and a time of 0.2-2h.

32. The method according to claim 30, wherein, Granulation results in a material particle size of 1-5mm.

33. The method according to claim 32, wherein, Granulation results in a material particle size of 2-4 mm.

34. The method of claim 30, wherein, The method also includes: cross-linking the granulated product under the action of a cross-linking agent.

35. The method according to claim 34, wherein, The crosslinking method is as follows: the granulated product is immersed in a crosslinking agent solution with a crosslinking agent concentration of 0.1-1wt%, the crosslinking temperature is 20-40℃, and the crosslinking time is 30-120min.

36. The method according to claim 34, wherein, The crosslinking agent is selected from at least one of aldehyde compounds; And / or, the method further includes: acid washing the crosslinked product after crosslinking.

37. The method of claim 36, wherein, The crosslinking agent is selected from at least one of C1-C5 monoaldehydes and C1-C5 dialdehydes.

38. The lithium adsorbent material prepared by the method according to any one of claims 15-37.

39. The lithium adsorbent material according to claim 38, wherein, The average particle size of the lithium adsorbent material is 1-5 mm.

40. The lithium adsorbent material according to claim 39, wherein, The average particle size of the lithium adsorbent material is 2-4 mm.

41. The application of the lithium adsorbent material according to any one of claims 38-40 in lithium extraction from salt lakes.

Images