Silicate mineral-based lithium ion sieve adsorbent and preparation method thereof

Abstract

The invention relates to the technical field of lithium ion adsorption, in particular to a silicate mineral-based lithium ion sieve adsorbent and a preparation method thereof. The method comprises the following steps: S1, calcining silicate mineral powder in an air atmosphere, soaking in deionized water, filtering and washing a sample for multiple times, and drying; s2, titanium dioxide powder and minerals are mixed and fully ground, the mixture is uniformly dispersed in a lithium hydroxide solution for a hydrothermal reaction, centrifugation and drying are performed, and white precipitates are obtained; s3, calcining the white precipitate in a nitrogen atmosphere to obtain an adsorbent precursor; and S4, placing the adsorbent precursor in a hydrochloric acid solution, magnetically stirring, centrifugally recovering, washing and drying to obtain the mineral-based lithium ion sieve adsorbent. The lithium ion sieve adsorbent obtained by the preparation method disclosed by the invention not only has extremely high lithium ion adsorption capacity and relatively high adsorption rate, but also has extremely high selectivity to lithium ions.

Description

Technical Field

[0001] The invention relates to the technical field of lithium ion adsorption, and in particular to a silicate mineral-based lithium ion sieve adsorbent and a preparation method thereof. Background Art

[0002] Global lithium resources are mainly divided into two categories, solid lithium ore and salt lake brine lithium ore, which account for 21.6% and 78.3% of the total reserves respectively. Therefore, the recovery of lithium resources in salt lakes is crucial.

[0003] At present, the ways to recover lithium resources from brine and seawater include precipitation, adsorption, extraction, membrane separation and ion exchange. Among them, precipitation is costly, with low recovery efficiency and purity; extraction is prone to damage to equipment; membrane separation and ion exchange have high process requirements; adsorption has high capacity and high selectivity, good cycle stability and simple process, and is a good lithium recovery method.

[0004] The basic principle of the adsorption method is to use an adsorption material that is selective for lithium ions to recover lithium, desorb after recovery, obtain a lithium ion solution with less impurities, and finally synthesize the corresponding lithium product according to demand. At present, the adsorbent selection of the adsorption method is mainly aluminum adsorbent, manganese adsorbent and titanium adsorbent. The adsorption capacity of aluminum adsorbent is low, and manganese adsorbent is prone to disproportionation reaction, with a high dissolution rate and easy to the environment. Therefore, titanium adsorbent has a broad application prospect.

[0005] Patent CN118145699A discloses a method of synthesizing a mixed crystal structure having two crystal forms, rutile and anatase, by using metatitanic acid as an initial titanium source and regulating the calcination temperature. However, in practice, the sample calcined by this method is prone to agglomeration, resulting in a decrease in the adsorption capacity of the material.

[0006] Patent CN117772123A discloses a method for synthesizing titanium-based lithium ion sieves, which comprises mixing a lithium-containing compound, a titanium-containing compound, polyethylene glycol PEG400, and water for hydrothermal reaction, drying and calcining the product to obtain a precursor, mixing the precursor with EVOH composite rubber, extruding and forming granules, drying, and acidifying to obtain the titanium-based lithium ion sieve. However, the synthesis process is relatively complicated and the adsorption capacity is not high. Summary of the invention

[0007] The purpose of the present invention is to address the above-mentioned deficiencies in the prior art and to provide a silicate mineral-based lithium ion sieve adsorbent having high adsorption capacity, high selectivity and low synthesis cost and a preparation method thereof.

[0008] The method for preparing a silicate mineral-based lithium ion sieve adsorbent of the present invention comprises the following steps:

[0009] S1. Calcine the silicate mineral powder in air atmosphere, then soak it in deionized water, filter and wash the sample several times and then dry it;

[0010] S2, mixing titanium dioxide powder and mineral, grinding them thoroughly, evenly dispersing them in lithium hydroxide solution for hydrothermal reaction, centrifuging and drying to obtain a white precipitate;

[0011] S3, calcining the white precipitate under a nitrogen atmosphere to obtain an adsorbent precursor;

[0012] S4. The adsorbent precursor is placed in a hydrochloric acid solution and stirred with a magnetic stirrer, and then centrifuged, washed, and dried to obtain a silicate mineral-based lithium ion sieve adsorbent.

[0013] Furthermore, in step S1, the silicate mineral is one of the silicate minerals selected from diatomite, kaolin, halloysite, attapulgite and vermiculite.

[0014] Furthermore, in step S1, the calcination temperature is 180-200°C, the calcination time is 3-5 hours, and the heating rate is 5-10°C / min.

[0015] Furthermore, in step S1, the deionized water soaking time is 12-24 hours; the drying temperature is 50-80° C., and the drying time is 8-12 hours.

[0016] Furthermore, in step S2, the molar ratio of Li to Ti in the lithium hydroxide and titanium dioxide is 1.8-2.2:0.9-1.1, and the mass ratio of titanium dioxide to silicate mineral is 2-3:0.5-5.

[0017] Furthermore, in step S2, the concentration of LiOH is 0.8-1.6 mol / L.

[0018] Furthermore, in step S2, the hydrothermal temperature is 160-180° C., and the insulation time is 24-48 hours.

[0019] Furthermore, in step S3, the calcination temperature is 550-600°C, 3-5h, and the heating rate is 4-6°C / min.

[0020] Furthermore, in step S2, the grinding time is 0.5-1h; the ultrasonic time is 10-30min, and the stirring time is 30-60min.

[0021] Furthermore, in step S4, the concentration of hydrochloric acid is 0.05-0.4 mol / L.

[0022] Furthermore, in step S4, the solid-liquid ratio of the precursor and hydrochloric acid is 0.9-1 g: 200-250 mL.

[0023] Furthermore, in step S4, the stirring time is 12-24 hours.

[0024] Furthermore, in step S4, the drying temperature is 50-70° C., and the drying time is 8-12 hours.

[0025] A silicate mineral-based lithium ion sieve adsorbent prepared by the above-mentioned preparation method.

[0026] In the synthesis process of the silicate mineral-based lithium ion sieve adsorbent provided by the present invention, the mineral not only serves as a carrier, thereby increasing the specific surface area and porosity of the material, promoting the dispersion of Li2TiO3, and increasing the adsorption capacity of the adsorbent; at the same time, an alkaline hydrothermal environment is utilized to promote the dissolution of Si in the silicate mineral, so that the dissolved Si participates in and affects the synthesis of Li2TiO3, increases the adsorption active sites for lithium recovery, increases the compressive stress between the material structure, and thereby increases the adsorption capacity.

[0027] Minerals are hydrophilic and have good ion exchange capacity, which accelerates the contact between lithium ions and active sites and improves the adsorption rate. The addition of minerals also enables the material to obtain higher porosity and specific surface area, and increases the contact probability between the adsorbent and lithium ions, further improving the adsorption rate.

[0028] The silicate mineral-based lithium ion sieve adsorbent obtained by the preparation method of the present invention not only has extremely high lithium ion adsorption capacity and relatively fast adsorption rate, but also has extremely high selectivity for lithium ions.

[0029] The synthesis process of the invention is simple, and while improving the adsorption performance, the costs of lithium source and titanium source are reduced. It has high economic benefits, is suitable for large-scale production, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a scanning electron microscope image of the vermiculite-based titanium-based lithium ion sieve adsorbent prepared in Example 1;

[0031] Figure 2 is a transmission electron microscope image of the vermiculite-based titanium-based lithium ion sieve adsorbent prepared in Example 1;

[0032] Figure 3 and Figure 4 are XRD images of the adsorbent precursor LTO-VMT prepared in Example 1 and the adsorbent precursor LTO prepared in Comparative Example 1;

[0033] Figure 5 This is the compressive stress distribution of the titanium-based lithium ion sieve adsorbent prepared in Comparative Example 1;

[0034] Figure 6 is the compressive stress distribution of the vermiculite-based titanium-based lithium ion sieve adsorbent prepared in Example 1;

[0035] Figure 7 Capacity-time curves of adsorption tests of the vermiculite-based titanium-based lithium ion sieve adsorbent prepared in Example 1 and the titanium-based lithium ion sieve adsorbent prepared in Comparative Example 1. DETAILED DESCRIPTION

[0036] The following are specific embodiments of the present invention and the accompanying drawings to further describe the technical solution of the present invention, but the present invention is not limited to these embodiments.

[0037] Embodiment 1

[0038] A method for preparing a mineral-based lithium ion sieve, using a hydrothermal synthesis method, specifically comprises the following steps:

[0039] Step A: 10 g of mineral vermiculite powder was calcined at 200° C. for 4 h in an air atmosphere, and then soaked in deionized water for 24 h. The sample was filtered and washed multiple times, dried at 80° C. for 8 h, and then sealed and stored.

[0040] Step B: 0.25g TiO2 and 0.1g treated vermiculite were mixed, ground for 30min, dispersed in 40mL 0.8mol / L LiOH solution, and deionized water was ultrasonically treated for 5min for degassing. After stirring at room temperature for 30min, the mixed solution was placed in an autoclave and stored at 170℃ for 48h. After cooling to 20℃, a white precipitate was obtained by centrifugation and dried in a vacuum oven. Finally, the white precipitate was annealed at 600℃ for 3h in a nitrogen atmosphere to obtain the adsorbent precursor LTO-VMT.

[0041] Step C: 0.1 g of the precursor was placed in 20 mL of 0.2 M HCl solution and magnetically stirred. After stirring for 24 h, the white sample was recovered by centrifugation and washed with deionized water until pH = 7. Finally, the sample was dried at 60 ° C for 8 h to obtain a vermiculite-based lithium ion sieve adsorbent. The adsorbent was named HTO-1.

[0042] Comparative Example 1

[0043] A comparative sample was obtained by the same procedure as Example 1 but without adding vermiculite, and was named HTO.

[0044] A method for preparing a titanium-based lithium ion sieve, using a hydrothermal synthesis method, specifically comprises the following steps:

[0045] 0.25g TiO2 was dispersed in 40mL 0.8mol / L LiOH solution, and deionized water was ultrasonically treated for 5min for degassing. After stirring at room temperature for 30min, the mixed solution was placed in an autoclave and stored at 170℃ for 48h. After cooling to 20℃, a white precipitate was obtained by centrifugation and dried in a vacuum oven. Finally, the white precipitate was annealed at 600℃ for 3h to obtain the adsorbent precursor LTO.

[0046] 0.1 g of the precursor was placed in 20 mL of 0.2 M HCl solution and magnetically stirred. After stirring for 24 h, the white sample was recovered by centrifugation and washed with deionized water until pH = 7. Finally, the sample was dried at 60 ° C for 8 h to obtain a titanium-based lithium ion sieve adsorbent, which was named HTO.

[0047] Here, HTO-1 is named HTO-VMT, its precursor is LTO-VMT, and the precursor of HTO is named LTO. In order to prove the advantages of adding vermiculite, the following characterization analysis was done:

[0048] Table 1 shows the pores and specific surface areas of vermiculite-based titanium-based lithium ion sieve adsorbent and titanium-based lithium ion sieve adsorbent. Figure 7 Capacity-time curves of adsorption tests of vermiculite-based titanium-based lithium ion sieve adsorbent and titanium-based lithium ion sieve adsorbent.

[0049] Table 1

[0050] Material Name Porosity Specific surface area HTO 0.283348cm3 / g 40.2020m2 / g HTO-VMT 0.297766cm3 / g 60.9672m2 / g

[0051] from Figure 7 It can be seen that the adsorption rate of the vermiculite-based titanium-based lithium ion sieve adsorbent is higher than that of the titanium-based lithium ion sieve adsorbent. This is because the addition of vermiculite enables the material to obtain a higher porosity and specific surface area (as can be seen from Table 1), and the contact probability between the adsorbent and lithium ions is increased. Therefore, the adsorption rate of the material is faster than that of the sample without vermiculite.

[0052] Figure 1 is a scanning electron microscope image of the vermiculite-based titanium-based lithium ion sieve adsorbent prepared in Example 1; Figure 2 is a transmission electron microscope image of the vermiculite-based titanium-based lithium ion sieve adsorbent prepared in Example 1; Figure 1 and Figure 2 It can be seen that Li2TiO3 is in the form of small particles with uniform particle size and good particle integrity, and is evenly distributed on the vermiculite lamellar structure without obvious agglomeration.

[0053] Figure 3 and Figure 4 is the XRD image of the adsorbent precursor LTO-VMT prepared in Example 1 and the adsorbent precursor LTO prepared in Comparative Example 1; Figure 3It can be seen that the main phases of the material are Li2TiO3 (PDF#00-033-0831) and vermiculite, and the vermiculite peak is mainly at 9°. XRD shows that the vermiculite-based titanium-based lithium ion sieve adsorbent was successfully synthesized. Figure 4 In the figure, the peak shift of the material at 18°-19° can infer that Si successfully participated in the synthesis of Li2TiO3 particles.

[0054] Figure 5 This is the compressive stress distribution of the titanium-based lithium ion sieve adsorbent prepared in Comparative Example 1; Figure 6 The compressive stress distribution of the vermiculite-based titanium-based lithium ion sieve adsorbent prepared in Example 1 is shown in FIG. Figure 5 and Figure 6 From the compressive stress distribution, we can see that the blue area of ​​HTO-VMT is larger and the compressive stress is greater, which confirms the doping of Si to Li2TiO3. In summary, vermiculite can not only provide a carrier, but also provide a Si source, which changes the structure of Li2TiO3 and thus improves the adsorption performance of the material.

[0055] The adsorption capacity of sample HTO-1 was tested. The test steps and methods are as follows: 0.1g of material was taken and placed in 50ml of adsorption solution for 24h. The concentration of Li was determined by inductively coupled plasma optical emission spectroscopy (ICP-OES). The test temperature was selected as 25℃, the adsorption solution was LiCl, the concentration was 200PPM, and the pH of the solution was 12.

[0056] The solution before and after adsorption was detected using inductively coupled plasma optical emission spectroscopy (ICP-OES), the concentration of Li ions in the solution before and after adsorption was measured, and the adsorption capacity of the adsorbent was calculated according to the formula Qe = (Co-Ce) * V / m. Where Qe is the adsorption capacity at equilibrium, Co is the initial concentration of ions in the solution before adsorption, Ce is the ion concentration in the solution after adsorption, V is the volume of the solution, and m is the mass of the adsorbent added.

[0057] Conclusion: The adsorption capacity of HTO-1 was measured to be 35.63 mg / g, while the adsorption capacity of the sample HTO without vermiculite was only 28.7 mg / g. And according to the characterization analysis, the addition of vermiculite can improve the adsorption performance of the material.

[0058] A selective adsorption test was performed on sample HTO-1, and an adsorption solution containing LiCl, NaCl and KCl was prepared, and the concentrations of LiCl, NaCl and KCl were all 200 PPM, and the pH was 12.

[0059] The concentrations of Li, Na and K were determined by inductively coupled plasma optical emission spectroscopy (ICP-OES), and the corresponding adsorption capacities were calculated.

[0060] The results are as follows: Under the condition that LiCl, NaCl and KCl exist in the solution at the same time, the adsorption capacity of the material for Li ions is 32.69 mg / g, the adsorption capacity of the material for Na ions is 0.17 mg / g, and the adsorption capacity of the material for K ions is 0.32 mg / g. The separation coefficient of the material for Li ions and Na ions is 217.19, and the separation coefficient for Li ions and K ions is 123.51.

[0061] Embodiment 2

[0062] The difference between this example and Example 1 is that in step A, 10 g of montmorillonite powder is calcined at 200° C. in an air atmosphere for 4 h, then soaked in deionized water for 24 h, the sample is filtered and washed multiple times, dried at 80° C. for 8 h, and then sealed and stored. The remaining steps are the same as in Example 1, and the mineral-based lithium ion sieve prepared in this example is named HTO-2.

[0063] The adsorption capacity of HTO-2 was tested. The test equipment and test method were the same as those of HTO-1. The adsorption capacity of HTO-2 was obtained as follows: 32.2 mg / g.

[0064] Embodiment 3

[0065] The difference between this example and Example 1 is that in step A, 10 g of attapulgite is calcined at 200° C. in an air atmosphere for 4 h, then soaked in deionized water for 24 h, the sample is filtered and washed multiple times, dried at 80° C. for 8 h, and then sealed and stored. The remaining steps are the same as in Example 1, and the mineral-based lithium ion sieve prepared in this example is named HTO-3.

[0066] The adsorption capacity of HTO-3 was tested using the same testing equipment and testing method as HTO-1. The adsorption capacity of HTO-3 was 31.57 mg / g.

[0067] Embodiment 4

[0068] The difference between this example and Example 1 is that in step A, 10 g of diatomaceous earth is calcined at 200° C. in an air atmosphere for 4 h, then soaked in deionized water for 24 h, the sample is filtered and washed multiple times, dried at 80° C. for 8 h, and then sealed and stored. The remaining steps are the same as in Example 1, and the mineral-based lithium ion sieve prepared in this example is named HTO-4.

[0069] The adsorption capacity of HTO-4 was tested using the same equipment and method as HTO-1, and the adsorption capacity of HTO-4 was obtained as follows: 34.58 mg / g.

[0070] Embodiment 5

[0071] The difference between this example and Example 4 is that in step B, 0.5 g TiO2 and 0.1 g treated vermiculite are mixed, ground for 30 min, dispersed in 40 mL 0.8 mol / L LiOH solution, and deionized water is ultrasonically treated for 5 min for degassing. After stirring at room temperature for 30 minutes, the mixed solution is placed in an autoclave, stored at 170° C. for 48 h, cooled to 20° C., centrifuged to obtain a white precipitate, and dried in a vacuum oven. Finally, the white precipitate is annealed at 600° C. in a nitrogen atmosphere for 3 hours.

[0072] The remaining steps are the same as those in Example 4. The mineral-based lithium ion sieve prepared in this example is named HTO-5.

[0073] The adsorption capacity of HTO-5 was tested using the same equipment and method as HTO-1, and the adsorption capacity of HTO-5 was obtained as follows: 29.19 mg / g.

[0074] Embodiment 6

[0075] The difference between this example and Example 5 is that in step B, 0.5 g TiO2 and 0.1 g treated vermiculite are mixed, ground for 30 min, dispersed in 40 mL 1.6 mol / L LiOH solution, and deionized water is ultrasonically treated for 5 min for degassing. After stirring at room temperature for 30 minutes, the mixed solution is placed in an autoclave, stored at 170°C for 48 hours, cooled to 20°C, centrifuged to obtain a white precipitate, and dried in a vacuum oven. Finally, the white precipitate is annealed at 600°C for 3 hours in a nitrogen atmosphere.

[0076] The remaining steps are the same as those in Example 4. The mineral-based lithium ion sieve prepared in this example is named HTO-6.

[0077] The adsorption capacity of HTO-6 was tested using the same equipment and method as HTO-1, and the adsorption capacity of HTO-6 was obtained as follows: 32.2 mg / g.

[0078] Embodiment 7

[0079] The difference between this example and Example 1 is that in step B, 0.25g TiO2 and 0.05g treated vermiculite are mixed, ground for 30min, dispersed in 40mL 0.8mol / L LiOH solution, and deionized water is ultrasonically treated for 5min for degassing. After stirring at room temperature for 30 minutes, the mixed solution is placed in an autoclave, stored at 170°C for 48h, cooled to 20°C, centrifuged to obtain a white precipitate, and dried in a vacuum oven. Finally, the white precipitate is annealed at 600°C for 3 hours in a nitrogen atmosphere.

[0080] The remaining steps are the same as those in Example 4. The mineral-based lithium ion sieve prepared in this example is named HTO-7.

[0081] The adsorption capacity of HTO-7 was tested using the same equipment and method as HTO-1, and the adsorption capacity of HTO-7 was obtained as follows: 34.3 mg / g.

[0082] Embodiment 8

[0083] The difference between this example and Example 1 is that in step B, 0.25g TiO2 and 0.2g treated vermiculite are mixed, ground for 30min, dispersed in 40mL 0.8mol / L LiOH solution, and deionized water is ultrasonically treated for 5min for degassing. After stirring at room temperature for 30 minutes, the mixed solution is placed in an autoclave, stored at 170°C for 48h, cooled to 20°C, centrifuged to obtain a white precipitate, and dried in a vacuum oven. Finally, the white precipitate is annealed at 600°C for 3 hours in a nitrogen atmosphere.

[0084] The remaining steps are the same as those in Example 4. The mineral-based lithium ion sieve prepared in this example is named HTO-8.

[0085] The adsorption capacity of HTO-8 was tested using the same equipment and method as HTO-1, and the adsorption capacity of HTO-8 was 28 mg / g.

[0086] For matters not mentioned above, the prior art applies.

[0087] Although some specific embodiments of the present invention have been described in detail through examples, those skilled in the art should understand that the above examples are for illustration only and are not intended to limit the scope of the present invention. Those skilled in the art to which the present invention belongs may make various modifications or supplements to the specific embodiments described or replace them in a similar manner, but they will not deviate from the direction of the present invention or exceed the scope defined by the attached claims. Those skilled in the art should understand that any modifications, equivalent substitutions, improvements, etc. made to the above embodiments based on the technical essence of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing a silicate mineral-based lithium ion sieve adsorbent, Features: The steps include: S1. Calcine the silicate mineral powder in air atmosphere, then soak it in deionized water, filter and wash the sample several times and then dry it; S2, mixing titanium dioxide powder and mineral, grinding them thoroughly, evenly dispersing them in lithium hydroxide solution for hydrothermal reaction, centrifuging and drying to obtain a white precipitate; S3, calcining the white precipitate under a nitrogen atmosphere to obtain an adsorbent precursor; S4. The adsorbent precursor is placed in a hydrochloric acid solution and stirred with a magnetic stirrer, and then centrifuged, washed, and dried to obtain a silicate mineral-based lithium ion sieve adsorbent.

2. The preparation method according to claim 1, Features: In step S1, the silicate mineral is one of the silicate minerals diatomite, kaolin, halloysite, attapulgite, and vermiculite.

3. The preparation method according to claim 1, Features: In step S1, the calcination temperature is 180-200°C, the calcination time is 3-5 hours, and the heating rate is 5-10°C / min.

4. The preparation method according to claim 1, Features: In step S1, the deionized water soaking time is 12-24 hours; the drying temperature is 50-80° C., and the drying time is 8-12 hours.

5. The preparation method according to claim 1, Features: In step S2, the molar ratio of Li to Ti in the lithium hydroxide and titanium dioxide is 1.8-2.2:0.9-1.1, and the mass ratio of titanium dioxide to silicate mineral is 2-3:0.5-5.

6. The preparation method according to claim 1, Features: In step S2, the concentration of LiOH is 0.8-1.6 mol / L.

7. The preparation method according to claim 1, Features: In step S2, the hydrothermal temperature is 160-180° C., and the insulation time is 24-48 hours.

8. The preparation method according to claim 1, Features: In step S3, the calcination temperature is 550-600°C, the calcination time is 3-5h, and the heating rate is 4-6°C / min.

9. The preparation method according to claim 1, Features: In step S2, the grinding time is 0.5-1h; the ultrasonic time is 10-30min, and the stirring time is 30-60min; In step S4, the concentration of hydrochloric acid is 0.05-0.4 mol / L; In step S4, the solid-liquid ratio of the precursor and hydrochloric acid is 0.9-1 g: 200-250 mL; In step S4, the stirring time is 12-24h; In step S4, the drying temperature is 50-70° C. and the drying time is 8-12 hours.

10. A silicate mineral-based lithium ion sieve adsorbent prepared by the preparation method according to any one of claims 1 to 9.

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