Lithium ion adsorbent as well as preparation method and application thereof

Abstract

The invention relates to the field of adsorption materials, and discloses a lithium ion adsorbent and a preparation method and application thereof. The lithium ion adsorbent comprises a polyvinyl chloride molecular chain and a polymer molecular chain A, wherein the polymeric molecular chain A comprises a structural unit I from crown ether containing vinyl and a structural unit II from a vinyl silane modified lithium ion sieve. The vinyl silane modified lithium ion sieve in the lithium ion adsorbent can be connected with a polymer molecular chain through a chemical bond, so that the lithium ion sieve can be uniformly dispersed on a polymer skeleton, and the lithium ion adsorbent has excellent structural stability, high adsorption capacity and high magnesium-lithium selectivity; and the solution loss rate of the lithium ion sieve is obviously reduced.

Description

Technical Field

[0001] This invention relates to the field of adsorption materials, specifically to a lithium-ion adsorbent, 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 polyurethane (PU), polyvinylidene fluoride (PVDF), and polyvinyl chloride (PVC) as binders for granulation. However, the granular adsorbents prepared have poor hydrophilicity and are prone to burying the powder adsorbent, which leads to a significant decrease in adsorption capacity and poor long-term cycle performance.

[0004] Therefore, it is urgent to solve the problems of poor hydrophilicity, adsorbent encapsulation, and long-term degradation of the cycling performance of PVC-based granulated products. Summary of the Invention

[0005] The purpose of this invention is to overcome the problems of low adsorption capacity, high lithium ion sieve dissolution loss, and poor magnesium-lithium selectivity in existing technologies using polyvinyl chloride as a skeleton granulation products. This invention provides a lithium ion adsorbent, its preparation method, and its application. In this lithium ion adsorbent, the vinylsilane-modified lithium ion sieve can be chemically bonded to the polymer molecular chain, allowing the lithium ion sieve to be uniformly dispersed on the polymer skeleton. This results in the lithium ion adsorbent exhibiting excellent structural stability, high adsorption capacity, and high magnesium-lithium selectivity, while significantly reducing the dissolution loss of the lithium ion sieve.

[0006] To achieve the above objectives, the first aspect of the present invention provides a lithium-ion adsorbent, wherein the lithium-ion adsorbent comprises a polyvinyl chloride molecular chain and a polymer molecular chain A;

[0007] The polymer molecular chain A includes structural unit I from a vinyl-containing crown ether and structural unit II from a vinylsilane-modified lithium-ion sieve.

[0008] A second aspect of the present invention provides a method for preparing a lithium-ion adsorbent, wherein the preparation method includes:

[0009] (1) A vinyl silane was used to modify a lithium-ion sieve to obtain a vinyl silane-modified lithium-ion sieve;

[0010] (2) Polyvinyl chloride, vinyl-containing crown ether, vinyl silane-modified lithium ion sieve are mixed with the first solvent to obtain the first mixture;

[0011] (3) The initiator is mixed with the second solvent to obtain a second mixture;

[0012] (4) The first mixture is added dropwise to the second mixture to carry out the polymerization reaction, and a lithium ion adsorbent is obtained.

[0013] A third aspect of the present invention provides a lithium-ion adsorbent prepared by the above-described preparation method.

[0014] The fourth aspect of the present invention provides an application of the above-mentioned lithium-ion adsorbent in lithium extraction, preferably in lithium extraction in a liquid environment.

[0015] Through the above technical solutions, the lithium-ion adsorbent, its preparation method, and its application provided by the present invention achieve the following beneficial effects:

[0016] In the lithium-ion adsorbent provided by this invention, the vinylsilane-modified lithium-ion sieve can be connected to the polymer molecular chains forming the framework through chemical bonds. During long-term use, the lithium-ion sieve is not easily detached, reducing the loss of lithium-ion sieve during use and improving the stability of the lithium-ion adsorbent. Furthermore, the vinylsilane-modified lithium-ion sieve has excellent compatibility with the polymer framework, allowing the lithium-ion sieve to be uniformly dispersed in the polymer framework, reducing the embedding phenomenon of lithium-ion sieve in the lithium-ion adsorbent. This results in the lithium-ion adsorbent having high adsorption and desorption rates, selectivity, and stability. At the same time, the structural unit II from the vinylsilane-modified lithium-ion sieve present in the lithium-ion adsorbent can significantly reduce the manganese dissolution loss of the lithium-ion sieve, especially the manganese-based lithium-ion sieve.

[0017] Furthermore, the manganese-based lithium ion sieve in the lithium ion adsorbent provided by the present invention works in conjunction with the crown ether structure in the polymer framework, which can further improve the adsorption capacity and magnesium-lithium selectivity of the lithium ion adsorbent. Attached Figure Description

[0018] Figure 1 This is a SEM image of the cross-section of the lithium-ion adsorbent in Example 1;

[0019] Figure 2 This is a SEM image of the lithium-ion adsorbent profile in Comparative Example 2. Detailed Implementation

[0020] 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.

[0021] To achieve the above objectives, the first aspect of the present invention provides a lithium-ion adsorbent, wherein the lithium-ion adsorbent comprises a polyvinyl chloride molecular chain and a polymer molecular chain A.

[0022] The polymer molecular chain A includes structural unit I from a vinyl-containing crown ether and structural unit II from a vinylsilane-modified lithium-ion adsorbent.

[0023] In this invention, the vinylsilane-modified lithium-ion sieve in the lithium-ion adsorbent can be connected to the polymer molecular chains forming the framework through chemical bonds. During long-term use, the lithium-ion sieve is not easily detached, reducing the loss of lithium-ion sieve during use and improving the stability of the lithium-ion adsorbent. Furthermore, the vinylsilane-modified lithium-ion sieve has excellent compatibility with the polymer framework, allowing the lithium-ion sieve to be uniformly dispersed in the polymer framework, reducing the embedding phenomenon of lithium-ion sieve in the lithium-ion adsorbent. This results in the lithium-ion adsorbent having high adsorption and desorption rates, selectivity, and stability. At the same time, the structural unit II from the vinylsilane-modified lithium-ion sieve present in the lithium-ion adsorbent can significantly reduce the manganese dissolution loss of the lithium-ion sieve, especially the manganese-based lithium-ion sieve.

[0024] Furthermore, the semi-interpenetrating network structure formed between polymer molecular chain A and polyvinyl chloride molecular chain can significantly increase the connectivity of PVC channels. In particular, the structural unit I (crown ether structure) contained in polymer molecular chain A can improve the adsorption capacity of lithium ions and the magnesium-lithium selectivity of lithium ion adsorbent.

[0025] According to the present invention, based on the total weight of the lithium-ion adsorbent, the content of the polyvinyl chloride molecular chain is 16-24 wt%; the content of structural unit I in the polymer molecular chain A is 2-9 wt%, and the content of structural unit II in the polymer molecular chain A is 70-82 wt%.

[0026] In this invention, the inventors discovered that when the content of polyvinyl chloride molecular chains, structural unit I and structural unit II in polymer molecular chain A of the lithium ion adsorbent meets the above-mentioned range, the lithium ion adsorbent has excellent adsorption capacity. At the same time, the lithium ion adsorbent has strong selectivity for lithium ions and excellent resistance to solvent damage.

[0027] In this invention, the sum of the contents of the polyvinyl chloride molecular chain, structural unit I in polymer molecular chain A, and structural unit II in polymer molecular chain A is 100 wt%.

[0028] In this invention, the contents of polyvinyl chloride molecular chains, structural unit I, and structural unit II in the lithium-ion adsorbent are determined by X-ray photoelectron spectroscopy (XPS). Specifically, the content of vinyl chloride molecular chains is obtained from the Cl element content (mass percentage of vinyl chloride structural units = percentage of chlorine / 35.5 × relative atomic mass of vinyl chloride), and the content of structural unit II is obtained from the Mn metal content (mass percentage of lithium-ion sieve = mass percentage of manganese / relative atomic mass of manganese × relative atomic mass of lithium-ion sieve). The remainder is the content of structural unit I (1 - mass percentage of vinyl chloride structural units - mass percentage of lithium-ion sieve).

[0029] Furthermore, based on the total weight of the lithium-ion adsorbent, the content of the polyvinyl chloride molecular chain is 18-20 wt%; the content of structural unit I in the polymer molecular chain A is 3-6 wt%, and the content of structural unit II in the polymer molecular chain A is 74-77 wt%.

[0030] According to the present invention, the vinyl-containing crown ether is selected from 4-vinylbenzo-15-crown 5 and / or 4-vinylbenzo-18-crown ether-6.

[0031] In this invention, selecting the aforementioned specific types of vinyl-containing crown ethers can improve the magnesium-lithium selectivity and adsorption capacity of lithium adsorbent materials.

[0032] In one specific embodiment of the present invention, preferably, the vinyl-containing crown ether is 4-vinylbenzo-15-crown-5.

[0033] According to the present invention, the vinyl silane is selected from at least one of vinyltriethoxysilane, vinyltrimethoxysilane, vinyltri(2-methoxyethoxy)silane, vinyltriisopropoxysilane, methylvinyldimethoxysilane, and vinyltriacetoxysilane.

[0034] In one specific embodiment of the present invention, preferably, the vinylsilane is vinyltriisopropoxysilane.

[0035] According to the present invention, the thickness of the coating layer formed by vinylsilane in the vinylsilane modified lithium ion sieve is 0.5-2 nm.

[0036] In this invention, when the thickness of the coating layer formed by vinyl silane in the vinyl silane-modified lithium-ion sieve is controlled to meet the above-mentioned range, it can ensure excellent compatibility between the lithium-ion sieve and the polymer. The resulting vinyl silane-modified lithium-ion sieve can be uniformly dispersed in the polymer framework, and the loading of the vinyl silane-modified lithium-ion sieve in the polymer framework is increased. Furthermore, the lithium-ion sieve in the resulting lithium-ion adsorbing material has a high specific surface area, thereby improving the adsorption capacity of the lithium-ion adsorbing material.

[0037] In this invention, the thickness of the coating layer formed by vinylsilane in the vinylsilane-modified lithium-ion sieve was observed and measured using TEM transmission electron microscopy.

[0038] In one specific embodiment of the present invention, the thickness of the coating layer formed by vinylsilane in the vinylsilane-modified lithium-ion sieve is 0.8-1.7 nm.

[0039] According to the present invention, the lithium ion sieve is a manganese-based lithium ion sieve.

[0040] In this invention, a manganese-based lithium ion sieve is used as the lithium ion sieve, which can cooperate with the crown ether structure in the polymer skeleton, thereby further improving the adsorption capacity and magnesium-lithium selectivity of the lithium ion adsorbent.

[0041] Furthermore, the lithium ions are screened from LiMn2O4 and Li 1.6 Mn 1.6 O4, Li 1.33 Mn 1.67 O4, Li4Mn5O 12 At least one of LiMnO2.

[0042] According to the present invention, the average particle size of the lithium-ion adsorbent is 2-4 mm.

[0043] In this invention, when the lithium-ion adsorbent has the aforementioned specific average particle size, it can ensure that the lithium-ion adsorbent has a high packing density when used for lithium extraction in a liquid environment, thereby ultimately improving the adsorption capacity and selectivity for lithium.

[0044] In this invention, the average particle size of the lithium-ion adsorbent material is measured using vernier calipers. Specifically, the testing method involves placing the adsorbent between the two clips of the vernier caliper, with the clips holding the diameter of the adsorbent, and then taking the reading. Each adsorbent particle is measured using the vernier caliper, and the average value is then calculated.

[0045] According to the present invention, the average pore size of the lithium-ion adsorbent is 1-10 μm.

[0046] In this invention, when the lithium-ion adsorbent has the aforementioned specific average pore size, it enables the lithium-ion adsorbent to have a high saturation adsorption capacity when used for liquid lithium extraction.

[0047] In one specific embodiment of the present invention, the lithium-ion adsorbent has an average pore size of 3-5 μm.

[0048] In this invention, the average pore size of the lithium-ion adsorbent refers to the average pore size of the lithium-ion adsorbent profile, measured using a scanning electron microscope. Specifically, the lithium-ion adsorbent material is cut open, and 10 observation points are randomly selected from the profile for scanning electron microscopy testing. Each observation area is not less than 500 × 500 μm, and the average value is calculated.

[0049] A second aspect of the present invention provides a method for preparing a lithium-ion adsorbent, wherein the preparation method includes the following steps:

[0050] (1) A vinyl silane was used to modify a lithium-ion sieve to obtain a vinyl silane-modified lithium-ion sieve;

[0051] (2) Polyvinyl chloride, vinyl-containing crown ether, vinyl silane-modified lithium ion sieve are mixed with the first solvent to obtain the first mixture;

[0052] (3) The initiator is mixed with the second solvent to obtain a second mixture;

[0053] (4) The first mixture is added dropwise to the second mixture to carry out the polymerization reaction, and a lithium ion adsorbent is obtained.

[0054] In this invention, in the presence of polyvinyl chloride (PVC), a vinyl silane-modified lithium-ion sieve is polymerized with a vinyl-containing crown ether. During the polymerization of the vinyl silane-modified lithium-ion sieve and the vinyl-containing crown ether to form polymer molecular chains, entanglement occurs between the lithium-ion sieve and the PVC molecular chains, forming a polymer backbone with an interpenetrating network structure. This not only allows the lithium-ion sieve to be uniformly dispersed within the polymer backbone, but also ensures that the lithium-ion sieve and the backbone are connected by chemical bonds. During long-term use, the lithium-ion sieve is less prone to detachment, resulting in a lithium-ion adsorbent that exhibits both high adsorption and desorption rates and high stability.

[0055] According to the present invention, the lithium-ion sieve is a manganese-based ion sieve. Further, the lithium-ion sieve is selected from LiMn2O4, Li... 1.6 Mn 1.6 O4, Li 1.33 Mn 1.67 O4, Li4Mn5O 12 At least one of LiMnO2.

[0056] In this invention, the average particle size of the lithium ion sieve is 0.05-500 μm.

[0057] According to the present invention, the vinyl silane is selected from at least one of vinyltriethoxysilane, vinyltrimethoxysilane, vinyltri(2-methoxyethoxy)silane, vinyltriisopropoxysilane, methylvinyldimethoxysilane, and vinyltriacetoxysilane, preferably vinyltriisopropoxysilane.

[0058] According to the present invention, the mass ratio of the lithium ion sieve to the vinylsilane is 1:0.1-0.8.

[0059] In this invention, when the weight ratio of vinylsilane to lithium ion sieve is controlled to meet the above-mentioned range, it can be ensured that the obtained vinylsilane-modified lithium ion sieve contains sufficient reactive groups that can react with vinyl crown ethers. This enables the formation of an interpenetrating network structure between polyvinyl chloride molecular chains and polymer molecular chains, while significantly improving the hydrophilicity of the lithium ion adsorbent.

[0060] According to the present invention, the modification is carried out under acidic conditions.

[0061] In one specific embodiment of the present invention, the modification conditions include: pH value of 1-3, reaction temperature of 70-80℃, and reaction time of 4-6h.

[0062] In this invention, the modification further includes ball milling and drying the modified product. Preferably, in this invention, the ball milling and drying result in a moisture content of less than or equal to 0.5 wt% for the vinylsilane-modified lithium-ion sieve.

[0063] In this invention, when the moisture content of the vinylsilane-modified lithium-ion sieve is controlled to meet the above-mentioned range, phase separation between the polymer and the vinylsilane-modified lithium-ion sieve due to the presence of moisture can be avoided, which would lead to a decrease in the compatibility between the polymer molecular chain containing the vinylsilane-modified lithium-ion sieve structural unit and the polyvinyl chloride molecular chain.

[0064] In this invention, the water content of the hydroxyl-modified lithium ion screen refers to the free water content in the hydroxyl-modified lithium ion screen.

[0065] According to the present invention, the thickness of the coating layer formed by vinylsilane in the vinylsilane modified lithium ion sieve is 0.5-2 nm.

[0066] In this invention, when the thickness of the coating layer formed by vinyl silane in the vinyl silane-modified lithium-ion sieve is controlled to meet the above-mentioned range, excellent compatibility between the lithium-ion sieve and the polymer can be guaranteed. The vinyl silane-modified lithium-ion sieve obtained thereby can be uniformly dispersed in the polymer skeleton, and the loading of the vinyl silane-modified lithium-ion sieve in the polymer skeleton is increased. Furthermore, the lithium-ion sieve in the resulting lithium-ion adsorbent has a high specific surface area, thereby improving the adsorption capacity of the lithium-ion adsorbent.

[0067] According to the present invention, the weight-average molecular weight of the polyvinyl chloride is 50,000 to 110,000 g / mol.

[0068] In this invention, polyvinyl chloride with the aforementioned specific weight-average molecular weight is used, which more easily forms an interpenetrating network structure with polymer molecular chains A containing vinylsilane-modified lithium-ion sieve structural units and vinyl crown ether structural units.

[0069] According to the present invention, the vinyl-containing crown ether is selected from 4-vinylbenzo-15-crown 5 and / or 4-vinylbenzo-18-crown ether-6.

[0070] According to the present invention, in step (2), based on the total weight of the polyvinyl chloride, the vinyl-containing crown ether and the first solvent, the amount of polyvinyl chloride is 8-12 wt%, the amount of vinyl-containing crown ether is 1-5 wt%, and the mass ratio of the vinyl silane modified lithium ion sieve to the polyvinyl chloride is 2-6:1.

[0071] In this invention, when the amounts of polyvinyl chloride, vinyl-containing crown ether, and vinylsilane-modified lithium-ion sieve are controlled to meet the above requirements, the adsorption performance of the lithium-ion adsorbent can be significantly improved, the service life of the lithium-ion adsorbent can be increased, and the resistance to solvent damage can be enhanced.

[0072] Further, in step (2), based on the total weight of the polyvinyl chloride, the vinyl-containing crown ether and the first solvent, the amount of polyvinyl chloride used is 9-10 wt%, the amount of vinyl-containing crown ether used is 2-4 wt%, and the mass ratio of the vinyl silane modified lithium ion sieve to the polyvinyl chloride is 3-5:1.

[0073] In this invention, there is no particular limitation on the type of the first solvent, but an organic solvent is preferred, and it is sufficient to ensure that polyvinyl chloride, vinyl crown ether, and vinylsilane modified lithium ion sieve are fully and uniformly mixed. For example, the first solvent is selected from at least one of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and dimethyl sulfoxide.

[0074] There is no particular limitation on the amount of the first solvent, as long as it can ensure that the polyvinyl chloride, the vinyl silane-modified lithium ion sieve, and the vinyl monomer containing electron-withdrawing groups are fully mixed.

[0075] In this invention, there are no particular limitations on the mixing conditions in step (2), as long as the polyvinyl chloride, vinyl silane modified lithium ion sieve and vinyl monomer containing electron-withdrawing groups are mixed evenly. For example, the mixing conditions include a mixing temperature of 30-70°C, preferably 30-50°C.

[0076] In a preferred embodiment of the present invention, polyvinyl chloride, a vinyl-containing crown ether, and a first solvent are mixed, followed by the addition of vinylsilane for modification and further mixing. By employing the above preferred embodiment, the microstructure, such as the pore structure, of the lithium-ion adsorbent can be controlled, resulting in a significant increase in the adsorption capacity of the lithium-ion adsorbent.

[0077] According to the present invention, the initiator is selected from at least one of potassium persulfate, ammonium persulfate and azobisisobutyronitrile.

[0078] According to the present invention, the amount of the initiator is 0.5-3 wt%, based on the total amount of vinylsilane-modified lithium-ion sieve and the vinyl-containing crown ether.

[0079] In this invention, when the amount of initiator is controlled to meet the above-mentioned range, a suitable polymerization rate can be achieved between the vinylsilane-modified lithium-ion sieve and the vinyl-containing crown ether, thereby controlling the polyvinyl chloride molecular chain and polymer molecular chain A to form an interpenetrating network structure at a suitable rate.

[0080] In this invention, the second solvent is water.

[0081] In one specific embodiment of the present invention, the concentration of the initiator in the second mixture is 1-5 wt%.

[0082] According to the present invention, the dripping rate is 1-5 mL / min.

[0083] In this invention, when the rate at which the first mixture is added to the second mixture is controlled to meet the above-mentioned range, a suitable polymerization rate can be achieved between the vinylsilane-modified lithium ion sieve and the vinyl-containing crown ether, thereby controlling the polyvinyl chloride molecular chain and polymer molecular chain A to form an interpenetrating network structure at a suitable rate.

[0084] Furthermore, the dropping rate is 2-3 mL / min.

[0085] According to the present invention, the conditions for the polymerization reaction include: a polymerization temperature of 30-75°C and a polymerization time of 2-12 h.

[0086] According to the present invention, the method further includes the step of washing the material that adsorbs lithium ions with an acidic solution.

[0087] In this invention, the material that adsorbs lithium ions is a lithium ion adsorption precursor. The material is washed with an acidic solution to remove the lithium ions from the precursor. + and H + Exchange is used to activate the precursor, resulting in an H-type lithium-ion sieve, such as Li. 1.33 Mn 1.67 O4 is converted to H 1.33 Mn 1.67 O4. H-type lithium ion sieves have a specific adsorption effect on lithium ions.

[0088] According to the present invention, the material adsorbing lithium ions is circulated and washed by an acidic solution under the action of a peristaltic pump.

[0089] Furthermore, the acidic solution is selected from at least one of hydrochloric acid, phosphoric acid, and sulfuric acid.

[0090] Furthermore, the concentration of the acidic solution is 0.1-1 mol / L.

[0091] Furthermore, the flow rate of the peristaltic pump is 1-6 BV / h, and the circulation time is 1-24h.

[0092] In this invention, when the conditions for circulating washing or the concentration of the acidic solution are controlled to meet the above-mentioned range, ion exchange can be guaranteed without damaging the structure of the ion sieve.

[0093] In one specific embodiment of the present invention, the concentration of the acidic solution is 0.1-0.6 mol / L; the flow rate of the peristaltic pump is 2-5 BV / h; and the circulation time is 4-24h.

[0094] A third aspect of the present invention provides a lithium-ion adsorbent prepared by the above method.

[0095] The fourth aspect of the present invention provides an application of the above-mentioned lithium-ion adsorbent in lithium extraction, preferably in lithium extraction in a liquid environment.

[0096] The present invention will be described in detail below through embodiments.

[0097] The adsorbent materials prepared in the examples and comparative examples were subjected to the following measurements:

[0098] The moisture content of the vinylsilane-modified lithium-ion sieve was determined using a precision moisture balance EM120-HR.

[0099] The average pore size and average particle size of the lithium-ion adsorbent were measured by scanning electron microscopy.

[0100] The contents of polyvinyl chloride (PVC) molecular chains, structural unit I, and structural unit II in the lithium-ion adsorbent were determined by X-ray photoelectron spectroscopy (XPS). Specifically, the content of PVC molecular chains was obtained from the Cl element content (mass percentage of PVC structural unit = chlorine content percentage / 35.5 × relative atomic mass of PVC), and the content of structural unit II was obtained from the Mn metal content (mass percentage of lithium-ion sieve = mass percentage of manganese / relative atomic mass of manganese × relative atomic mass of lithium-ion sieve). The remainder was the content of structural unit I (1 - mass percentage of PVC structural unit - mass percentage of lithium-ion sieve).

[0101] Adsorption capacity: The obtained granulated particles (4g) were packed into a glass column and acid-washed (using H2O). +The adsorption-desorption cycle was performed for 24 hours using 0.5 mol / L hydrochloric acid at a rate of 2 BV / h. A mixture of lithium chloride and magnesium chloride (lithium ion concentration 1000 mg / L, magnesium ion concentration 1000 mg / L, pH adjusted to 9.5 with ammonia-ammonium chloride buffer, V = 400 mL) was then pumped in at a flow rate of 2 BV / h using a peristaltic pump for 24 hours to desorb lithium ions from the particles. The particles were then washed with deionized water until neutral, constituting one cycle. During one adsorption process, the change in adsorption capacity over time was monitored, and the saturated adsorption capacity Q was calculated using the following formula:

[0102]

[0103] 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).

[0104] Distribution coefficient (K) d (Unit: mg / L) represents the affinity of the reactive adsorbent for ions. Selectivity coefficient. The partition coefficient (K) indicates the preference of an adsorbent for ions A when adsorbing ions A and B. A higher value indicates better selectivity for ions A, reflecting the adsorbent's selectivity for different ions. d The ratio of ).

[0105]

[0106] In the above formula, C0 represents the concentration of each ion in the solution before adsorption, in mg / L; C e K represents the concentration of each ion at adsorption saturation, in mg / L; V is the solution volume, in mL; and m is the adsorbent mass, in g. A K is the partition coefficient of A ions; B It is the partition coefficient of B ions.

[0107] Test method for Mn dissolution: 4g of manganese-based adsorbent was packed into a glass column, and 500mL of 5M hydrochloric acid was added. The column was circulated at a rate of 2mL / min for 24h. The concentration of Mn in the hydrochloric acid was determined by ICP-MS. Mn Dissolution rate η, η% = (c Mn ×V) / m Mn ×100%, where m Mn c represents the mass of Mn in 4g of manganese-based adsorbent, in g. Mn, where g / L is the unit and V is the volume of hydrochloric acid, in L.

[0108] The percentage decrease in adsorption capacity after 30 cycles = (Q1-Q30) / Q1×100%, where Q1 is the initial adsorption capacity and Q30 is the adsorption capacity on the 30th cycle.

[0109] In addition, in the following examples and comparative examples: all reagents were purchased from Bailingwei Technology Co., Ltd.

[0110] Example 1

[0111] (1) Take Li 1.6 Mn 1.6 O4 (average particle size 1 μm) was homogenized and mixed with an aqueous solution of vinyltriisopropoxysilane (pH adjusted to 2 with hydrochloric acid) to achieve a lithium-ion sieve to vinyltriisopropoxysilane mass ratio of 1:0.1. The mixture was stirred at 70°C for 5 hours. The solution was then centrifuged, and the solid phase was dried to obtain a vinylsilane-modified lithium-ion sieve. The moisture content of the dried powder was less than 0.5%.

[0112] (2) Dissolve 10g of polyvinyl chloride (weight average molecular weight 50,000 g / mol) and 2g of 4-vinylbenzo-15-crown-5 in 88g of DMF, stir at 60°C for 24h, then add 40g of the vinylsilane-modified lithium-ion sieve prepared in step (1), stir at 60°C for 24h to obtain the first mixture. The amount of polyvinyl chloride is 10wt%, the amount of 4-vinylbenzo-15-crown-5 is 2wt%, and the mass ratio of vinylsilane-modified lithium-ion sieve to polyvinyl chloride is 4:1.

[0113] (3) The first mixture was added dropwise to a 1wt% (500mL) ammonium persulfate aqueous solution (second mixture) at a rate of 2mL / min, and reacted at 50℃ for 12h. The mixture was then rinsed with deionized water to obtain adsorbent material M1.

[0114] Example 2

[0115] (1) Take Li 1.6 Mn 1.6 O4 (average particle size 1 μm) was homogenized and mixed with an aqueous solution of vinyltriisopropoxysilane (pH adjusted to 2 with hydrochloric acid) to achieve a lithium-ion sieve to vinyltriisopropoxysilane mass ratio of 1:0.5. The mixture was stirred at 70°C for 5 hours. The solution was then centrifuged, and the solid phase was dried to obtain a vinylsilane-modified lithium-ion sieve. The moisture content of the dried powder was less than 0.5%.

[0116] (2) Dissolve 10g of polyvinyl chloride (weight average molecular weight 50,000 g / mol) and 4g of 4-vinylbenzo-15-crown-5 in 86g of DMF, stir at 60°C for 24h, then add 40g of the vinylsilane-modified lithium-ion sieve obtained in step (1), and stir at 60°C for 24h to obtain the first mixture. The amount of polyvinyl chloride is 10wt%, the amount of 4-vinylbenzo-15-crown-5 is 4wt%, and the mass ratio of vinylsilane-modified lithium-ion sieve to polyvinyl chloride is 4:1.

[0117] (3) The first mixture was added dropwise to a 1wt% (500mL) ammonium persulfate aqueous solution (the second mixture) at a rate of 2mL / min, and reacted at 50℃ for 12h. The mixture was then rinsed with deionized water to obtain the adsorbent material M2.

[0118] Example 3

[0119] (1) Take Li 1.6 Mn 1.6 O4 (average particle size 1 μm) was homogenized and mixed with an aqueous solution of vinyltriisopropoxysilane (pH adjusted to 2 with hydrochloric acid) to achieve a lithium-ion sieve to vinyltriisopropoxysilane mass ratio of 1:0.8. The mixture was stirred at 70°C for 5 hours. The solution was then centrifuged, and the solid phase was dried to obtain a vinylsilane-modified lithium-ion sieve. The moisture content of the dried powder was less than 0.5%.

[0120] (2) Dissolve 10g of polyvinyl chloride (weight average molecular weight 50,000 g / mol) and 3g of 4-vinylbenzo-15-crown-5 in 87g of DMF, stir at 60°C for 24h, then add 40g of the vinylsilane-modified lithium-ion sieve prepared in step (1), stir at 60°C for 24h to obtain the first mixture. The amount of polyvinyl chloride used is 10wt%, the amount of 4-vinylbenzo-15-crown-5 used is 3wt%, and the mass ratio of the vinylsilane-modified lithium-ion sieve to polyvinyl chloride is 4:1.

[0121] (3) The first mixture was added dropwise to a 1wt% (500mL) ammonium persulfate aqueous solution (second mixture) at a rate of 2mL / min, and reacted at 50℃ for 12h. The mixture was then rinsed with deionized water to obtain adsorbent material M3.

[0122] Example 4

[0123] (1) Same as Example 1.

[0124] (2) Dissolve 8g of polyvinyl chloride (weight average molecular weight 50,000 g / mol) and 1g of 4-vinylbenzo-15-crown-5 in 91g of DMF, stir at 60°C for 24h, then add 40g of the vinylsilane-modified lithium-ion sieve prepared in step (1), stir at 60°C for 24h to obtain the first mixture. The amount of polyvinyl chloride is 8wt%, the amount of 4-vinylbenzo-15-crown-5 is 1wt%, and the mass ratio of vinylsilane-modified lithium-ion sieve to polyvinyl chloride is 5:1.

[0125] (3) Same as in Example 1. Adsorbent material M4 was obtained.

[0126] Example 5

[0127] (1) Same as Example 1.

[0128] (2) Dissolve 12g of polyvinyl chloride and 5g of 4-vinylbenzo-15-crown-5 in DMF, stir at 60°C for 24h, then add 40g of the vinylsilane-modified lithium-ion sieve obtained in step (1), stir at 60°C for 24h to obtain the first mixture. The amount of polyvinyl chloride is 12wt%, the amount of 4-vinylbenzo-15-crown-5 is 5wt%, and the mass ratio of vinylsilane-modified lithium-ion sieve to polyvinyl chloride is 3.3:1.

[0129] (3) Same as in Example 1. Adsorbent material M5 was obtained.

[0130] Example 6

[0131] (1) Same as Example 1.

[0132] (2) Dissolve 10g of polyvinyl chloride (weight average molecular weight 50,000 g / mol) and 2g of 4-vinylbenzo-15-crown-5 in 88g of DMF, stir at 60°C for 24h, then add 30g of the vinylsilane-modified lithium-ion sieve prepared in step (1), stir at 60°C for 24h to obtain the first mixture. The amount of polyvinyl chloride used is 10wt%, the amount of 4-vinylbenzo-15-crown-5 used is 2wt%, and the mass ratio of the vinylsilane-modified lithium-ion sieve to polyvinyl chloride is 3:1.

[0133] (3) Same as in Example 1. Adsorbent material M6 was obtained.

[0134] Example 7

[0135] (1) Same as Example 1.

[0136] (2) Dissolve 6g of polyvinyl chloride (weight average molecular weight 50,000 g / mol) and 2g of 4-vinylbenzo-15-crown-5 in 88g of DMF, stir at 60°C for 24h, then add 50g of the vinylsilane-modified lithium-ion sieve prepared in step (1), stir at 60°C for 24h to obtain the first mixture. The amount of polyvinyl chloride is 6wt%, the amount of 4-vinylbenzo-15-crown-5 is 2wt%, and the mass ratio of vinylsilane-modified lithium-ion sieve to polyvinyl chloride is 8.3:1.

[0137] (3) Same as in Example 1. Adsorbent material M7 was obtained.

[0138] Example 8

[0139] Same as Example 1, except that in step (2), 4-vinylbenzo-15-crown-5 is replaced with 4-vinylbenzo-18-crown-ether-6. Adsorbent material M8 is obtained.

[0140] Example 9

[0141] Same as Example 1, except that in step (1), the silane coupling agent is replaced with vinyltriethoxysilane. Adsorbent material M9 is obtained.

[0142] Comparative Example 1

[0143] Similar to Example 1, step (1) is skipped, and the lithium ion sieve is directly used in step (2) to obtain adsorbent material N1.

[0144] Comparative Example 2

[0145] Similar to Example 1, step (1) is omitted, and the lithium-ion sieve is directly used in step (2), without adding 4-vinylbenzo-15-crown-5. Adsorbent material N2 is obtained.

[0146] Comparative Example 3

[0147] Same as in Example 1, except that 4-vinylbenzo-15-crown-5 is not added in step (2). Adsorbent material N3 is obtained.

[0148] The lithium-ion adsorbent materials prepared in the examples and comparative examples were tested. The contents of polyvinyl chloride molecular chains, vinyl crown ether structural unit I and vinyl silane modified lithium-ion sieve structural unit II in the lithium-ion adsorbent, the thickness of the coating layer formed by vinyl silane in the vinyl silane modified lithium-ion sieve, the average particle size and average pore size of the lithium-ion adsorbent are shown in Table 1.

[0149] Table 1

[0150]

[0151]

[0152] Test case

[0153] The adsorption capacity of the lithium-ion adsorbent, the dissolution rate of Mn, the adsorption capacity after 30 cycles, and the magnesium-lithium selectivity coefficient were tested, and the results are shown in Table 3.

[0154] Table 2

[0155]

[0156] As can be seen from Tables 1, 2, and 3, compared to Comparative Examples 1-3, the lithium-ion adsorbents prepared in Examples 1-9 include polyvinyl chloride molecular chains and polymer molecular chains A containing structural units from crown ether structural units and from vinylsilane-modified lithium-ion sieves. Furthermore, an interpenetrating network structure is formed in situ between the polyvinyl chloride molecular chains and polymer molecular chains A, enabling uniform dispersion of the lithium-ion sieve within the polymer framework and reducing the embedding phenomenon of the lithium-ion sieve in the lithium-ion adsorbent. When this lithium-ion adsorbent is used for liquid lithium extraction, it exhibits high adsorption capacity, magnesium-lithium selectivity coefficient, and low manganese dissolution rate. Moreover, it maintains high adsorption capacity even after 30 operating cycles, demonstrating excellent service life.

[0159] Figure 1 This is a SEM image of the lithium-ion adsorbent from Example 1. Figure 1 It can be seen that the pores in lithium-ion adsorbent A1 are highly interconnected and well-developed, with a filamentous network structure.

[0160] Figure 2 This is a SEM image of the lithium-ion adsorbent in Comparative Example 2, from... Figure 2 It can be seen that the lithium-ion adsorbent D2 powder is largely agglomerated, with no through pores and the pores are blocked.

[0161] 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-ion adsorbent, characterized in that, The lithium-ion adsorbent comprises polyvinyl chloride molecular chains and polymer molecular chain A; The polymer molecular chain A includes structural unit I from a vinyl-containing crown ether and structural unit II from a vinylsilane-modified lithium-ion sieve.

2. The lithium-ion adsorbent according to claim 1, wherein, Based on the total weight of the lithium-ion adsorbent, the content of the polyvinyl chloride molecular chain is 16-24 wt%; the content of structural unit I in polymer molecular chain A is 2-9 wt%, and the content of structural unit II in polymer molecular chain A is 70-82 wt%. Preferably, based on the total weight of the lithium-ion adsorbent, the content of the polyvinyl chloride molecular chain is 18-20 wt%; the content of structural unit I in polymer molecular chain A is 3-6 wt%, and the content of structural unit II in polymer molecular chain A is 74-77 wt%.

3. The lithium-ion adsorbent according to claim 1 or 2, wherein, The vinyl-containing crown ether is selected from 4-vinylbenzo-15-crown 5 and / or 4-vinylbenzo-18-crown ether-6; preferably 4-vinylbenzo-15-crown-5; Preferably, the vinyl silane is selected from at least one of vinyltriethoxysilane, vinyltrimethoxysilane, vinyltri(2-methoxyethoxy)silane, vinyltriisopropoxysilane, methylvinyldimethoxysilane, and vinyltriacetoxysilane, and is more preferably vinyltriisopropoxysilane.

4. The lithium-ion adsorbent according to any one of claims 1-3, wherein, The thickness of the coating layer formed by vinyl silane in the vinyl silane-modified lithium-ion sieve is 0.5-2 nm; Preferably, the moisture content of the vinylsilane-modified lithium-ion sieve is less than or equal to 0.5 wt%. Preferably, the lithium ion screen is a manganese-based ion screen; Preferably, the lithium ion screening is selected from LiMn2O4, Li 1.6 Mn 1.6 O4, Li 1.33 Mn 1.67 O4, Li4Mn5O 12 At least one of LiMnO2.

5. The lithium-ion adsorbent according to any one of claims 1-4, wherein, The average particle size of the lithium-ion adsorbent is 2-4 mm. Preferably, the lithium-ion adsorbent has an average pore size of 1-10 μm.

6. A method for preparing a lithium-ion adsorbent, characterized in that, The preparation method includes the following steps: (1) A vinyl silane was used to modify a lithium-ion sieve to obtain a vinyl silane-modified lithium-ion sieve; (2) Polyvinyl chloride, vinyl-containing crown ether, vinyl silane-modified lithium ion sieve are mixed with the first solvent to obtain the first mixture; (3) The initiator is mixed with the second solvent to obtain a second mixture; (4) The first mixture is added dropwise to the second mixture to carry out the polymerization reaction, and a lithium ion adsorbent is obtained.

7. The preparation method according to claim 6, wherein, The lithium ion sieve is a manganese-based ion sieve, preferably selected from LiMn2O4 and Li 1.6 Mn 1.6 O4, Li 1.33 Mn 1.67 O4, Li4Mn5O 12 and at least one of LiMnO2; Preferably, the vinylsilane is selected from at least one of vinyltriethoxysilane, vinyltrimethoxysilane, vinyltri(2-methoxyethoxy)silane, vinyltriisopropoxysilane, methylvinyldimethoxysilane, and vinyltriacetoxysilane; more preferably, vinyltriisopropoxysilane. Preferably, the mass ratio of the lithium-ion sieve to the vinylsilane is 1:0.1-0.8; Preferably, the modification conditions include: pH value of 1-3, reaction temperature of 70-80℃, and reaction time of 4-6h; Preferably, the moisture content of the vinylsilane-modified lithium-ion sieve is less than or equal to 0.5 wt%. Preferably, the thickness of the coating layer formed by vinylsilane in the vinylsilane-modified lithium-ion sieve is 0.5-2 nm.

8. The preparation method according to claim 6 or 7, wherein, The weight-average molecular weight of the polyvinyl chloride is 50,000-110,000 g / mol; Preferably, in step (2), based on the total weight of the polyvinyl chloride, the vinyl-containing crown ether, and the first solvent, the amount of polyvinyl chloride used is 8-12 wt%, the amount of vinyl-containing crown ether used is 1-5 wt%, and the mass ratio of the vinyl silane modified lithium ion sieve to the polyvinyl chloride is 2-6:

1.

9. The preparation method according to any one of claims 6-8, wherein, The initiator is selected from at least one of potassium persulfate, ammonium persulfate, and azobisisobutyronitrile; Preferably, the amount of the initiator is 0.5-3 wt%, based on the total amount of the vinylsilane-modified lithium-ion sieve and the vinyl-containing crown ether.

10. The preparation method according to any one of claims 6-9, wherein, The dripping rate is 1-5 mL / min, preferably 2-3 mL / min; Preferably, the conditions for the polymerization reaction include: a polymerization temperature of 30-75°C and a polymerization time of 2-12 hours.

11. The preparation method according to any one of claims 6-10, wherein, The method further includes the step of washing the lithium-ion adsorbent with an acidic solution; Preferably, the lithium-ion adsorbent is circulated and washed using an acidic solution under the action of a peristaltic pump; Preferably, the acidic solution is selected from at least one of hydrochloric acid, phosphoric acid, and sulfuric acid; Preferably, the concentration of the acidic solution is 0.1-1 mol / L; Preferably, the flow rate of the peristaltic pump is 1-6 BV / h, and the circulation time is 1-24h.

12. A lithium-ion adsorbent prepared by the preparation method according to any one of claims 6-11.

13. The application of the lithium-ion adsorbent according to any one of claims 1-5 and 12 in lithium extraction, preferably in a liquid environment.

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