Granular aluminum salt-based lithium extraction adsorbent, and preparation method and application thereof

Abstract

The present application belongs to the field of preparation of adsorption separation materials, and relates to a preparation method of granular aluminum salt-based lithium extraction adsorbent, comprising: (1) dispersing lithium aluminum layered double hydroxide precursor into chitosan aqueous solution to form a uniform mixed slurry; wherein the pH value of the chitosan aqueous solution is controlled in the range of 3.5-7.5; (2) adding a crosslinking agent into the mixed slurry for mixing, and obtaining a composite gel product through crosslinking reaction and aging treatment; (3) after the composite gel product is subjected to screening and extrusion granulation, the granular aluminum salt-based lithium extraction adsorbent is obtained through drying, rinsing and dehydration treatment. Through the preparation of the composite gel, and the steps of screening, extrusion granulation, drying, rinsing and dehydration, the adsorbent with different particle sizes can be prepared. The prepared granular adsorbent has a large adsorption capacity for lithium, and has a low solution loss rate in use. The chitosan used as a granulation binder can be biodegraded. The adsorbent preparation process does not use organic solvents, and has the advantages of green, environmental protection, low cost and the like.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of preparation of adsorption separation materials, and particularly relates to a preparation method and application of a granular aluminum salt-based lithium extraction adsorbent. BACKGROUND

[0002] Lithium is a rare light metal element. Lithium and its compounds have been widely used in various industrial fields, among which, they are mainly used for producing various types of lithium batteries, and in addition, they also have important uses in the fields of aerospace, nuclear reactors, ceramics, glass and pharmaceuticals. The global consumption of lithium in 2021 is estimated to be 93,000 tons, an increase of 33% compared with 70,000 tons in 2020.

[0003] According to the statistics of the United States Geological Survey, the total lithium resource reserves in the world are about 89 million tons. The total lithium resource reserves in China are about 5.1 million tons, among which, the lithium in the salt lake brine in Qinghai and Tibet accounts for more than 85% of the total reserves in China, and the cost of extracting lithium from salt lake brine is usually 30%-50% lower than that of extracting lithium from granitic pegmatite deposits. However, the composition of salt lake brine is complex, especially the high magnesium / lithium ratio brings great challenges to the high selectivity extraction of lithium from brine.

[0004] The methods for extracting lithium from salt lake brine include solvent extraction, adsorption, electrodialysis and membrane separation, etc. Compared with other methods, the adsorption method has the advantages of high selectivity, environmental friendliness, low cost, high recovery efficiency, easy operation, etc. Manganese-based and titanium-based lithium ion sieves and lithium aluminum layered double hydroxides (i.e. aluminum salt-based lithium extraction adsorbents) all show excellent selectivity in the extraction of lithium from salt lake brine. Compared with lithium ion sieve adsorbents, aluminum-based lithium adsorbents have the advantages of simple preparation method, mild desorption conditions and good repeated use performance, etc., and have high application value in the extraction of lithium from salt lake brine. However, when the powder-like aluminum salt-based lithium extraction adsorbent with very small particle size is directly filled into a fixed bed column for use, the hydraulic conductivity of the adsorption column is very low, which limits its application in large-scale continuous industrial production. SUMMARY

[0005] In view of the above defects or improvement needs of the prior art, the purpose of the present application is to provide a preparation method of a granular aluminum salt-based lithium extraction adsorbent, which specifically comprises: first, a composite gel product of lithium aluminum layered double hydroxide precursor and chitosan is prepared, then the composite gel product is extruded and sieved to obtain composite gel particles, and then the particles are dried, rinsed and dehydrated to obtain a granular aluminum salt-based lithium extraction adsorbent with different particle sizes as needed. The prepared granular adsorbent has a large adsorption capacity for lithium, has a low dissolution loss rate during use, the chitosan used as a granulation binder can be biodegraded, water is used as a solvent throughout the adsorbent preparation process, and no organic solvent is needed, so that the granular adsorbent has the advantages of being green, low-carbon, environmentally friendly and low-cost. The prepared granular adsorbent can be filled into a fixed bed for continuous large-scale extraction of lithium resources from various lithium-containing aqueous solutions such as salt lake brine, thereby avoiding the problems of low hydraulic conductivity and difficult solid-liquid separation of the powder-like aluminum salt-based adsorbent in the fixed bed.

[0006] To achieve the above-mentioned purpose, in the first aspect of the present application, a preparation method of a granular aluminum salt-based lithium extraction adsorbent is provided, comprising:

[0007] (1) dispersing lithium aluminum layered double hydroxide precursor into a chitosan aqueous solution to form a uniform mixed slurry of chitosan and lithium aluminum layered double hydroxide precursor; wherein the pH value of the chitosan aqueous solution is controlled in the range of 3.5-7.5;

[0008] (2) adding a crosslinking agent to the mixed slurry in step (1) and mixing, and then performing crosslinking reaction and aging treatment to obtain a composite gel product of chitosan and lithium aluminum layered double hydroxide precursor;

[0009] (3) extruding and sieving the composite gel product in step (2) to obtain composite gel particles, and then drying, rinsing and dehydrating the particles to obtain a granular aluminum salt-based lithium extraction adsorbent.

[0010] As a preferred embodiment of the present application, in step (1), the chitosan aqueous solution is prepared by dissolving chitosan in an acidic aqueous solution; and the mass fraction of chitosan in the chitosan aqueous solution is 0.5%-5%.

[0011] As a preferred embodiment of the present application, in step (1), the mass ratio of chitosan to lithium aluminum layered double hydroxide precursor is 1:(1-8); and the temperature when the chitosan aqueous solution is mixed with the lithium aluminum layered double hydroxide precursor is 5-40℃.

[0012] As a preferred embodiment of the present application, in step (2), the crosslinking agent comprises at least one of glyoxal, malondialdehyde, butanedialdehyde and pentanedialdehyde, and the amount of the crosslinking agent is 0.1%-35% of the mass of chitosan.

[0013] As a preferred embodiment of the present application, in step (2), the temperature of the cross-linking reaction is 5-70°C, and the time of the cross-linking reaction is 5 min-24 h.

[0014] As a preferred embodiment of the present application, in step (2), the temperature of the aging is 20-60°C, and the time of the aging is 1 h-24 h.

[0015] As a preferred embodiment of the present application, after the composite gel product is extruded and granulated through a sieve with a mesh size of 5-50, the obtained composite gel particles are dried at 40-60°C for 1 h-24 h, rinsed, and dehydrated to obtain the granular aluminum salt-based lithium extraction adsorbent.

[0016] As a preferred embodiment of the present application, the lithium aluminum layered double hydroxide precursor is prepared by a coprecipitation method or a hydrothermal method.

[0017] In another aspect of the present application, a granular aluminum salt-based lithium extraction adsorbent prepared based on the method of the first aspect of the present application is provided.

[0018] In yet another aspect of the present application, the granular aluminum salt-based lithium extraction adsorbent provided in the first aspect of the present application is applied in lithium extraction, preferably in the extraction of lithium from salt lake brine, groundwater, seawater, or industrial lithium-containing wastewater.

[0019] Overall, compared with the prior art, the above technical solutions conceived by the present application mainly have the following technical advantages:

[0020] (1) The present application first forms a composite gel of chitosan and a lithium aluminum layered double hydroxide precursor, then extrudes and granulates the composite gel through a sieve to obtain composite gel particles, and finally obtains a granular adsorbent through drying, rinsing, and dehydration. Since the composite gel of the present application is formed under weakly acidic and neutral conditions, the collapse and destruction of the structure of the lithium aluminum layered double hydroxide precursor caused by the need to drop the gel beads in a strong alkaline receiving solution in the prior art can be avoided, and thus the significant reduction in the lithium extraction performance of the adsorbent can be further avoided. Because the main component of the lithium aluminum layered double hydroxide precursor is aluminum hydroxide, which can maintain its structure stable under weakly acidic and neutral conditions, but it will dissolve in a strong alkaline solution. The longer the gel beads are soaked in the strong alkaline receiving solution, the greater the degree of dissolution of the lithium aluminum salt precursor structure embedded in the gel beads, and thus the adsorption capacity of the gel beads will be greatly affected.

[0021] (2) The prepared composite gel particles have uniform distribution of cross-linking agent inside and outside, so the cross-linking degree inside and outside of the composite gel particles is uniform and controllable, and the particulate adsorbent with better mechanical strength can be obtained. This is because the composite gel is prepared by first dispersing the cross-linking agent uniformly in the mixed slurry of chitosan and lithium-aluminum layered double hydroxide precursor, and then initiating the cross-linking reaction, so that the composite gel with uniform cross-linking degree inside and outside can be obtained. However, the existing drop ball technology is to drop the gel balls in a strong alkaline receiving liquid, and then put the gel balls into an aqueous solution containing cross-linking agent to occur cross-linking reaction. However, the hydrophilicity of these cross-linking agents is generally poor, so it is not easy to diffuse from the outside of the gel balls to the inside, which may result in smaller cross-linking degree inside, and lower mechanical strength of the whole gel ball.

[0022] (3) The preparation method of the present application is to extrude the composite gel through a screen to form particles, and through the processing steps such as screening, the particle size of the prepared adsorbent can be controlled. Generally speaking, the smaller the particle size of the adsorbent, the larger the specific surface area, and the larger the adsorption capacity. Therefore, by selecting a screen with a larger mesh number, an aluminum salt-based lithium extraction adsorbent with smaller particle size can be prepared to increase its adsorption capacity. Therefore, the preparation method of the present application can not only obtain particles with different particle sizes by selecting screens with different mesh numbers, but also prepare particles with smaller particle sizes than the existing drop ball granulation technology. This is because the smaller the particle size of the dropped gel balls, the smaller the drop ball channel of the granulator needs to be. When the content of solid nanoparticles in the glue solution is high or the concentration of the glue solution is high, the drop ball channel of the granulator is easily blocked, making it difficult to prepare gel balls with smaller particle sizes by drop ball process.

[0023] (4) The screening granulation forming process of the present application can be carried out at room temperature, which is convenient to operate, has small equipment investment, high granulation efficiency and low cost. Compared with the drop ball granulation method in the prior art, only one ball can be dropped per unit time in one machine, while in the present application, more gel particles can be formed by selecting appropriate screens so that the composite gel can pass through multiple screen holes at the same time per unit time. In addition, when the content of solid nanoparticles in the glue solution is high or the concentration of the glue solution is high, the drop ball channel of the granulator is easily blocked, and often needs to be stopped for maintenance.

[0024] (5) The granulation binder of the present application has simple composition, low price and is green and environmentally friendly. Chitosan is used as the granulation binder in the present application, and chitosan is a deacetylated product of chitin, which is widely available and low in price, and can reduce the granulation cost. Chitosan is non-toxic and has good biocompatibility and biodegradability, and using chitosan as the granulation binder meets the green and low-carbon environmental protection requirements. In the process of preparing the particulate adsorbent using chitosan as the binder, only water is used as the solvent, and no organic solvent is needed, so the process of preparing the particulate adsorbent is green and environmentally friendly.

[0025] (6) Since chitosan has good hydrophilicity, and has good compatibility and combination with the hydrophilic lithium-aluminum layered double hydroxide, the composite adsorbent of lithium-aluminum layered double hydroxide and chitosan is beneficial to the diffusion of water molecules in the adsorbent particles, improves the adsorption performance of the granular adsorbent, and also reduces the pollution of oily pollutants in the brine to the adsorbent. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 A process flow chart for preparing the granular aluminum salt-based lithium extraction adsorbent of the present application is shown in the figure.

[0027] Figure 2 A photo of the granular aluminum salt-based lithium extraction adsorbent sample exemplified in Example 2 of the present application is shown in the figure.

[0028] Figure 3 A morphology diagram of the granular aluminum salt-based lithium extraction adsorbent exemplified in Example 2 of the present application obtained under a microscope is shown in the figure.

[0029] Figure 4 A scanning electron microscope diagram of the granular aluminum salt-based lithium extraction adsorbent exemplified in Example 2 of the present application is shown in the figure.

[0030] Figure 5 An XRD spectrum diagram of the granular aluminum salt-based lithium extraction adsorbent exemplified in Example 2 of the present application is shown in the figure.

[0031] Figure 6 An XRD spectrum diagram comparison of the granular aluminum salt-based lithium extraction adsorbent exemplified in Example 2-3 of the present application, the aluminum salt-based lithium extraction adsorbent exemplified in Comparative Example 1, and pure chitosan is shown in the figure.

[0032] Figure 7 A reuse diagram of the granular aluminum salt-based lithium extraction adsorbent exemplified in Example 2 of the present application is shown in the figure. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of the present application clearer and more apparent, the present application will be further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application, and are not used to limit the present application. In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as they do not conflict with each other.

[0034] In the embodiments of the present application, the preparation method of the granular aluminum salt-based lithium extraction adsorbent is as shown in the figure, and is specifically as follows: Figure 1

[0035] ​Step 1, prepare lithium-aluminum layered double hydroxide precursor by co-precipitation method or hydrothermal method, which does not need further washing and drying and other subsequent treatments, and can be directly dispersed in chitosan aqueous solution.

[0036] Step 2, dissolve chitosan in one of acidic aqueous solutions such as acetic acid aqueous solution, hydrochloric acid aqueous solution or sulfuric acid aqueous solution to obtain uniform chitosan aqueous solution. At the same time, according to the need, use hydrochloric acid or sodium hydroxide to adjust the pH value of the chitosan aqueous solution to 3.5-7.5, wherein the mass fraction of chitosan in the chitosan aqueous solution is 0.5%-5%.

[0037] At a temperature of 5-40℃, disperse the lithium-aluminum layered double hydroxide precursor in step 1 into the chitosan aqueous solution and fully mix by vigorous stirring to obtain a uniform mixed slurry, and the mass ratio of chitosan to lithium-aluminum layered double hydroxide precursor in the slurry is 1:(1-8).

[0038] Step 3, add a certain amount of crosslinking agent to the mixed slurry of chitosan and lithium-aluminum layered double hydroxide precursor prepared in step 2, uniformly stir, and then react at a certain temperature for a period of time and age for a period of time, finally obtain chitosan and lithium-aluminum layered double hydroxide precursor composite gel product.

[0039] The crosslinking agent of chitosan is at least one of glyoxal, malondialdehyde, butanedial, glutaraldehyde, and the amount of crosslinking agent is 0.1%-35% of the mass of chitosan; the crosslinking reaction temperature of chitosan is controlled in the range of 5-70℃, the crosslinking reaction time is controlled in the range of 5min-24h, and the gel aging time is controlled in the range of 1h-24h.

[0040] Step 4, after the composite gel product in step 3 is extruded and granulated through a 5-50 mesh (national standard sieve size) screen, the composite gel particles are vacuum dried at 40℃-60℃, and then rinsed and dehydrated to obtain granular aluminum salt-based lithium extraction adsorbent.

[0041] For example, the granular aluminum salt-based lithium extraction adsorbent can be further treated by vacuum drying or room temperature air drying to obtain granular adsorbent with a certain water content or completely dried granular adsorbent for standby use. The granular adsorbent needs to be rinsed and dehydrated for 12-24h before use, and can be directly filled into a fixed bed column for lithium extraction in various lithium-containing aqueous solutions including salt lake brine, groundwater, seawater and industrial lithium-containing wastewater.

[0042] The chemical composition of the simulated old salt lake brine used in the embodiments of the present application is shown in Table 1:

[0043] Table 1 Main ions and their concentrations in the simulated old salt lake brine (pH is 5.6):

[0044]

[0045] The specific implementation is as follows:

[0046] Example 1

[0047] Lithium chloride and aluminum chloride were dissolved in deionized water in a molar ratio of Li + : Al 3+ 1:2 to obtain a lithium-aluminum salt mixed solution. Under the action of intense mechanical stirring, a 12 mol / L NaOH solution was added dropwise to the lithium-aluminum salt mixed solution until the pH of the lithium-aluminum salt mixed solution reached 4.4. After the mixed solution was continuously stirred for 30 min, the supernatant was discarded by centrifugal separation to obtain a lithium-aluminum layered double hydroxide precursor precipitate (Li-Al-LDH).

[0048] The wet Li-Al-LDH (with a wet weight of 8.10 g and a dry weight of 2.4 g) was dispersed into 40 mL of a 3% chitosan aqueous solution (chitosan was dissolved in an acetic acid aqueous solution, and the pH of the chitosan aqueous solution was adjusted to 4.4), and the mixed slurry was intensively mechanically stirred in a 15°C water bath for 20 min. Then, under the condition of intense mechanical stirring, 4 mL of a glutaraldehyde aqueous solution (with a mass fraction of 4.5% of glutaraldehyde in the aqueous solution, and the total mass of the glutaraldehyde crosslinking agent being 15% of the mass of chitosan) was slowly added to the mixed slurry, and the crosslinking agent was uniformly dispersed in the mixed slurry. Then, the water bath temperature was increased to 40°C, and the reaction was continued at this temperature for 20 min until the composite gel was generated, and the composite gel was aged at room temperature for 4.5 h.

[0049] The composite gel was crushed and passed through a 20-mesh screen to obtain composite gel particles, which were vacuum dried at 55°C for 12 h. The dried gel particles were rinsed with deionized water three times, and were dehydrated by suction filtration. After surface air drying at room temperature, the granular aluminum salt-based lithium extraction adsorbent No. 1 was obtained.

[0050] Before use, the granular adsorbent No. 1 was rinsed with deionized water for 12 h at a solid-liquid ratio of 1 g: 100 mL. Then, the lithium-depleted granular adsorbent No. 1 was added to the simulated salt lake brine at a solid-liquid ratio of 1 g (dry weight of the adsorbent): 30 mL, and was oscillated in a constant-temperature water bath shaker at 30°C at a rotation speed of 200 rpm for 48 h. The equilibrium adsorption capacity of the adsorbent for lithium was measured to be 8.33 mg / g.

[0051] Example 2

[0052] The preparation method of the granular aluminum salt-based lithium extraction adsorbent is the same as that in Example 1, except that the amount of the wet Li-Al-LDH dispersed into the chitosan aqueous solution in Example 1 is adjusted: in the mixed slurry of chitosan and Li-Al-LDH in the present example, the wet weight of the added Li-Al-LDH is 12.2 g, the dry weight of which is 3.6 g, and the mass ratio of chitosan to Li-Al-LDH is 1:3, so that the granular aluminum salt-based lithium extraction adsorbent No. 2 is prepared.

[0053] Under the same adsorption conditions for determining the static adsorption amount of lithium by the adsorbent in Example 1, the equilibrium adsorption amount of lithium by the granular adsorbent No. 2 is measured to be 9.71 mg / g.

[0054] Figure 2 It is an optical photograph of the granular aluminum salt-based lithium extraction adsorbent in Example 2 of the present application, and compared with the gel beads prepared by the existing drop ball granulation technology, the particle size of the adsorbent of the present application appears much smaller in appearance; Figure 3 It is a morphology diagram of the granular aluminum salt-based lithium extraction adsorbent in Example 2 of the present application observed under a microscope, and as can be seen from the diagram, the shape of the granular adsorbent is irregular, and the particle size thereof is mainly in the range of 600-1000 microns; Figure 4 It is a scanning electron microscope diagram of the granular aluminum salt-based lithium extraction adsorbent in Example 2 of the present application, and even under the magnification of 40,000 times, no obvious lithium aluminum layered double hydroxide in the form of nanoparticles can be observed, indicating that the lithium aluminum layered double hydroxide is uniformly distributed in the chitosan gel network. Figure 5 As shown in the XRD spectrum of the granular aluminum salt-based lithium extraction adsorbent in Example 2, there is a very strong characteristic diffraction peak signal of lithium aluminum layered double hydroxide, indicating that a large amount of lithium aluminum layered double hydroxide capable of extracting lithium is distributed in the chitosan gel network.

[0055] Example 3

[0056] The preparation method of the granular aluminum salt-based lithium extraction adsorbent is the same as that in Example 1, except that the amount of the wet Li-Al-LDH dispersed into the chitosan aqueous solution in Example 1 is adjusted: in the mixed slurry of chitosan and Li-Al-LDH in the present example, the wet weight of the added Li-Al-LDH is 32.4 g, the dry weight of which is 9.6 g, and the mass ratio of chitosan to Li-Al-LDH is 1:8, so that the granular aluminum salt-based lithium extraction adsorbent No. 3 is prepared.

[0057] Under the same adsorption conditions for determining the static adsorption amount of lithium by the adsorbent in Example 1, the equilibrium adsorption amount of lithium by the granular adsorbent No. 3 is measured to be 11.86 mg / g.

[0058] Comparative Example 1

[0059] The wet precipitate of Li-Al-LDH was centrifuged and dried at 55°C under vacuum for 12h. The dried Li-Al-LDH was rinsed with deionized water for 12h to remove lithium, and then dried at 55°C under vacuum for 12h to obtain the lithium-removed Li-Al-LDH adsorbent, which was ground and passed through a 200-mesh sieve for use.

[0060] Under the same adsorption conditions as in Example 1 for determining the static adsorption amount of lithium by the adsorbent, the equilibrium adsorption amount of lithium by the lithium-removed Li-Al-LDH adsorbent was measured to be 6.50mg / g.

[0061] Figure 6 For comparison of the XRD spectra of the pure chitosan, the corresponding aluminum salt-based lithium extraction adsorbents in Comparative Example 1 and Examples 2-3, the characteristic diffraction peaks of lithium aluminum layered double hydroxide (compared with the standard card JCPDS 31-0704 of lithium aluminum layered double hydroxide LiAl2(OH)7-xH2O) appeared in the aluminum salt-based lithium extraction adsorbents in Comparative Example 1 and Examples 2-3, in addition to the pure chitosan. The higher the content of lithium aluminum layered double hydroxide in the granular adsorbent, the stronger the diffraction peak. Obviously, the diffraction peak intensity of Example 3 was higher than that of Example 2. The diffraction peak intensity of Comparative Example 1 was higher than that of Examples 2-3, because Comparative Example 1 was pure lithium aluminum layered double hydroxide.

[0062] Example 4

[0063] The preparation method of the granular aluminum salt-based lithium extraction adsorbent was the same as in Example 1, except that the screen for processing the composite gel product in Example 1 was adjusted. In this example, the prepared composite gel was crushed and passed through a 30-mesh sieve to obtain smaller gel particles, so that the granular aluminum salt-based lithium extraction adsorbent No. 4 was prepared.

[0064] Under the same adsorption conditions as in Example 1 for determining the static adsorption amount of lithium by the adsorbent, the equilibrium adsorption amount of lithium by the granular adsorbent No. 4 was measured to be 8.86mg / g.

[0065] Example 5

[0066] The preparation method of the granular aluminum salt-based lithium extraction adsorbent was the same as in Example 1, except that the screen for processing the composite gel product in Example 1 was adjusted. In this example, the prepared composite gel was crushed and passed through a 10-mesh sieve to obtain larger gel particles, so that the granular aluminum salt-based lithium extraction adsorbent No. 5 was prepared.

[0067] Under the same adsorption conditions as in Example 1 for determining the static adsorption amount of lithium by the adsorbent, the equilibrium adsorption amount of lithium by the granular adsorbent No. 5 was measured to be 7.79mg / g.

[0068] Example 6

[0069] The preparation method of granular aluminum salt-based lithium extraction adsorbent is the same as in Example 1, except that the amount of glutaraldehyde, the crosslinking agent added when preparing the composite gel in Example 1, is changed to 30% of the mass of chitosan. In this way, granular aluminum salt-based lithium extraction adsorbent No. 6 is prepared.

[0070] Under the same adsorption conditions as those used in Example 1 for determining the static adsorption capacity of the adsorbent for lithium, the equilibrium adsorption capacity of granular adsorbent No. 6 for lithium was determined to be 8.25 mg / g.

[0071] Example 7

[0072] The preparation method of the granular aluminum salt-based lithium extraction adsorbent is the same as that in Example 1, except that the crosslinking agent added when preparing the composite gel in Example 1 is changed to glyoxal, thus obtaining granular aluminum salt-based lithium extraction adsorbent No. 7.

[0073] Under the same adsorption conditions used in Example 1 to determine the static adsorption capacity of the adsorbent for lithium, the equilibrium adsorption capacity of granular adsorbent No. 7 for lithium was measured to be 7.45 mg / g.

[0074] Example 8

[0075] The reusability of granular adsorbent No. 2 prepared in Example 2 under static adsorption conditions was investigated. The lithium-desorbed granular adsorbent No. 2 was added to simulated old brine from a salt lake at a solid-liquid ratio of 1 g (dry weight of adsorbent): 30 mL. Adsorption was carried out for 48 h at 200 rpm in a constant-temperature water bath shaker at 30°C. After the adsorption process, the lithium-adsorbed granular adsorbent No. 2 was obtained by filtration, and the residual lithium concentration in the filtrate was determined by ICP-OES. Impurity ions adhering to the surface of adsorbent No. 2 were removed by rinsing with ice-cold deionized water at a solid-liquid ratio of 1 g: 30 mL. Then, the lithium-adsorbed granular adsorbent No. 2 was dispersed in deionized water at a solid-liquid ratio of 1 g: 100 mL, and lithium was removed by shaking at 200 rpm in a constant-temperature water bath shaker at 30°C for 4 h. The delithiated granular adsorbent No. 2 was obtained by filtration, thus completing the first adsorption-desorption cycle.

[0076] like Figure 7 As shown, the amount of lithium adsorbent No. 2 did not change significantly during 15 adsorption-desorption cycles, indicating that granular adsorbent No. 2 has good reusability.

[0077] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. Use of a particulate aluminosilicate-based lithium extraction adsorbent in the extraction of lithium, characterised in that, The application of the granular aluminum salt-based lithium extraction adsorbent in extracting lithium from salt lake brine, underground water, seawater or industrial lithium-containing wastewater is disclosed. (1) dispersing a lithium aluminum layered double hydroxide precursor precipitate Li-Al-LDH into a chitosan aqueous solution to form a uniform mixed slurry of chitosan and the lithium aluminum layered double hydroxide precursor; wherein the pH value of the chitosan aqueous solution is controlled in the range of 3.5-7.5; the mass fraction of chitosan in the chitosan aqueous solution is 3%-5%; and the mass ratio of chitosan to the lithium aluminum layered double hydroxide precursor is 1:(1-8); (2) adding a crosslinking agent into the mixed slurry in step (1) to mix, and obtaining a composite gel product of chitosan and the lithium aluminum layered double hydroxide precursor through crosslinking reaction and aging treatment; (3) extruding and granulating the composite gel product in step (2) through a screen to obtain composite gel particles, and then drying, rinsing and dehydrating the composite gel particles to obtain the granular aluminum salt-based lithium extraction adsorbent.

2. Use of the particulate aluminium salt-based lithium extraction adsorbent according to claim 1 for the extraction of lithium, characterized in that, In step (1), the chitosan aqueous solution is prepared by dissolving chitosan in an acidic aqueous solution.

3. Use of the particulate aluminium salt-based lithium extraction adsorbent according to claim 1 for the extraction of lithium, characterized in that, In step (1), the temperature of the chitosan aqueous solution mixed with the lithium aluminum layered double hydroxide precursor is 5-40℃.

4. Use of the particulate aluminium salt-based lithium extraction adsorbent according to claim 1 for the extraction of lithium, characterized in that, In step (2), the crosslinking agent includes at least one of glyoxal, malondialdehyde, succindialdehyde and glutaraldehyde, and the amount of the crosslinking agent is 0.1%-35% of the mass of chitosan.

5. Use of the particulate aluminium salt-based lithium extraction adsorbent according to claim 1 for the extraction of lithium, characterized in that, In step (2), the temperature of the crosslinking reaction is 5-70℃, and the time of the crosslinking reaction is 5 min-24 h.

6. Use of the particulate aluminium salt-based lithium extraction adsorbent according to claim 1 for the extraction of lithium, characterized in that, In step (2), the temperature of the aging is 20-60℃, and the time of the aging treatment is 1 h-24 h.

7. Use of the particulate aluminium salt-based lithium extraction adsorbent according to claim 1 for the extraction of lithium, characterized in that, In step (3), the composite gel product is extruded and granulated through a screen with a mesh size of 5-50, and then the obtained composite gel particles are dried at 40-60℃ for 1 h-24 h, rinsed and dehydrated to obtain the granular aluminum salt-based lithium extraction adsorbent.

8. Use of a particulate aluminium salt-based lithium extraction adsorbent according to any one of claims 1 to 7 for the extraction of lithium, characterized in that, The lithium aluminum layered double hydroxide precursor precipitate Li-Al-LDH is prepared by a coprecipitation method or a hydrothermal method.

Images