Lithium extraction adsorbent based on breathable titanic acid nanosheets as well as preparation and application of lithium extraction adsorbent

Abstract

The invention relates to the technical field of materials, and discloses a lithium extraction adsorbent based on breathable titanic acid nanosheets and preparation and application thereof.The preparation method comprises the steps that layered titanic acid is added into an ammonium solution, after standing, titanium oxide nanosheets of an accordion structure are obtained, then the titanium oxide nanosheets of a fish scale structure are obtained through drying and lodging, and the lithium extraction adsorbent based on the breathable titanic acid nanosheets is obtained. The lithium extraction adsorbent is obtained. The preparation method provided by the invention comprises the following steps: by taking layered titanic acid as a precursor, treating the precursor with an ammonium solution to obtain the accordion-structure titanium oxide nanosheet, and then lodging the accordion-structure titanium oxide nanosheet in a drying process to obtain the scale-structure titanium oxide nanosheet. The layered titanic acid with a novel structure is reported for the first time, the steps of the layered titanic acid are stacked tidily, the length is controllable, and the layered titanic acid is simple in preparation process, low in energy consumption, high in repeatability and high in adsorption performance.

Description

Technical Field

[0001] The present invention relates to the technical field of materials, and particularly relates to a lithium extraction adsorbent based on breathable titanic acid nanosheets and its preparation and application. Background Art

[0002] In the current global trend of energy transformation, lithium, as a key strategic metal, plays an indispensable role in the field of rechargeable batteries, especially in lithium-ion batteries. Lithium-ion batteries are widely used in electric vehicles, portable electronic devices, and large-scale energy storage systems, etc., due to their advantages such as high energy density, long cycle life, and low self-discharge rate. With the rapid development of the electric vehicle market and the increasing demand for renewable energy storage, the global demand for lithium has shown an explosive growth trend. In recent years, efficiently extracting lithium from low-grade lithium resources such as salt lake brine and seawater has become a key way to solve the contradiction between the supply and demand of lithium resources.

[0003] Currently, the main methods for lithium extraction from salt lakes are adsorption method, membrane separation methods (such as electrodialysis, nanofiltration), and extraction method. Among them, the adsorption method has become the mainstream because of its high selectivity and simple operation. The adsorption method has the characteristics of simple process and environmental friendliness in nuclear wastewater. Layered titanic acid-based adsorbent materials have received extensive attention in the adsorption field due to their good chemical stability, high theoretical adsorption capacity, and simple synthesis method. However, due to the influence of its own microstructure, charge density, and layer spacing, the adsorbed ions are not easy to diffuse into the interlayer, resulting in a relatively low actual adsorption efficiency of layered titanic acid. More seriously, due to the need to use acid treatment to regenerate the adsorbent during the continuous adsorption-desorption process, high-concentration or multiple acid picklings will damage the layered structure to a certain extent, thereby leading to a reduction in adsorption sites and a decrease in structural stability. Xu et al. prepared three-dimensional porous H 2 TiO 3 The adsorbent compared with the original H 2 TiO 3 nanoparticles, the adsorption capacity of three-dimensional porous H 2 TiO 3 is 76.3 mg·g -1 , compared with 44.8 mg·g 2 TiO 3 of H -1 nanoparticles, which is nearly twice as high, but its adsorption rate is still relatively low. Summary of the Invention

[0004] To overcome the defects of the above-mentioned existing technologies, the object of the present invention is to provide a lithium extraction adsorbent based on breathable titanium dioxide nanosheets and its preparation and application. The preparation method has mild reaction conditions, simple operation, and high repeatability. The breathable titanium dioxide nanosheets prepared by this method have controllable morphology and microstructure, fast adsorption rate, and high capacity.

[0005] To achieve the above object, the present invention provides a preparation method of a lithium extraction adsorbent based on breathable titanium acid nanosheets. Layered titanic acid with a plate-like morphology is added to an ammonium solution. After standing, titanium dioxide nanosheets with an accordion structure are obtained. After drying and lodging, titanium dioxide nanosheets with a fish scale structure are obtained, which is the lithium extraction adsorbent.

[0006] The structural formula of the layered titanic acid is H 0.8 Ti 2-x M x O 4 (x = 0.4 - 0.8), H 1.07 Ti 1.73 O 4 or H 2 O 2 -H 1.07 Ti 1.73 O 4 , where M is selected from Mg, Co, Ni, Cu, Zn, Mn(Ⅲ), Fe(Ⅲ)), H 1.07 Ti 1.73 O 4 , H 2 O 2 -H 1.07 Ti 1.73 O 4 of one kind.

[0007] The layered titanic acid of the present invention is prepared by existing conventional technologies. The preparation method of H 0.8 Ti 2-x M x O 4 (x = 0.4 - 0.8) can refer to the literature "Liao J, Hu Q, Sheng X, et al. ACS Materials Letters, 2022, 4(9): 1653 - 1659; Harada M, Sasaki T, Ebina Y, et al. Journal of Photochemistry and Photobiology A: Chemistry, 2002, 148(1 - 3): 273 - 276."; H 1.07 Ti 1.73 O 4The preparation method of can be found in the literature "Sasaki T, Kooli F, Iida M, et al. Chemistry of materials, 1998, 10 (12): 4123-4128."; H 2 O 2 -H 1.07 Ti 1.73 O 4 The preparation method can be found in the literature “Wang X. Chemical Communications, 2021, 57(60): 7394-7397.”.

[0008] As a further preferred technical solution of the present invention, the dosage ratio of titanic acid and ammonium solution is 0.2-1 g:15-100 mL.

[0009] As a further preferred technical solution of the present invention, the ammonium solution is at least one of dimethylaminoethanol, tetrabutylammonium hydroxide, trimethylamine, dimethylethanolamine, 3-dimethylamino-1-propanol, and N,N-dimethylbutylamine solution.

[0010] As a further preferred technical solution of the present invention, the static time is 30 minutes to 12 hours.

[0011] As a further preferred technical solution of the present invention, the length of the accordion-structured titanium oxide nanosheets is 2 μm to 5 mm, and the thickness is 2 to 200 nm.

[0012] According to another aspect of the present invention, the present invention also provides a lithium extraction adsorbent, which is prepared by the above method.

[0013] According to another aspect of the present invention, the present invention also provides an application of a lithium extraction adsorbent, in which fish-scale structured titanium oxide nanosheets are placed in a lithium ion solution to adsorb lithium ions and then transformed into accordion structured titanium oxide nanosheets with lithium ion intercalation, and the accordion structured titanium oxide nanosheets with lithium ion intercalation shrink to the original layered titanic acid after desorbing lithium ions in an acid solution.

[0014] Compared with the prior art, the present invention has the following beneficial technical effects:

[0015] The preparation method provided by the present invention uses layered titanic acid as a precursor, and obtains accordion-structured titanium oxide nanosheets through ammonium solution treatment, and then the accordion-structured titanium oxide nanosheets are made to fall down during the drying process to obtain fish-scale-structured titanium oxide nanosheets. The present invention is the first to report a layered titanic acid with a novel structure, whose steps are neatly stacked and whose length is controllable, and whose preparation process is simple, with low energy consumption, high repeatability and high adsorption performance.

[0016] The lithium extraction adsorbent provided by the present invention is placed in lithium chloride solutions of 20 mg / L and 100 mg / L respectively and stands still for 10 s, and 100% adsorption of Li + can be achieved. After desorption by treatment with low-concentration acid, the adsorbent shrinks to desorb Li + . After repeating the adsorption and desorption experiment for more than 10 times, the adsorbent still exhibits excellent adsorption rate, indicating its good cycle stability. Description of the Drawings

[0017] The present invention will be further described in detail below in conjunction with the drawings and specific embodiments.

[0018] Figure 1 (a) is the optical microscope image of the layered titanic acid precursor H 1.07 Ti 1.73 O 4 in Example 1; (b) is the optical microscope image of the expansion after adding ammonium solution to H 1.07 Ti 1.73 O 4 ;

[0019] Figure 2 is the fish scale structure obtained after the accordion-structured titanium oxide nanosheets in Example 1 are filtered and toppled over;

[0020] Figure 3 is the accordion structure obtained after re-expansion and contraction after adsorbing lithium ions in the adsorption experiment of Example 1;

[0021] Figure 4 is the optical microscope image of the accordion structure after acid contraction in the desorption experiment of Example 1;

[0022] Figure 5 is the adsorption time efficiency curve of Example 1 and Example 3.

[0023] The realization, functional characteristics and advantages of the object of the present invention will be further described in conjunction with the embodiments with reference to the drawings. Specific Embodiments

[0024] The following further describes the specific embodiments of the present invention in conjunction with the drawings. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0025] Unless otherwise defined, the technical terms used in the following embodiments have the same meaning as commonly understood by those skilled in the art to which the present invention pertains. The test reagents used in the following embodiments are all conventional biochemical reagents unless otherwise specified; the experimental methods are all conventional methods unless otherwise specified.

[0026] Term Explanation: There is a reversible transformation among the layered titanate precursor, the titanium oxide nanosheets with accordion structure, and the titanium oxide nanosheets with fish scale structure, which is called "breathable titanium oxide nanosheets".

[0027] Example 1

[0028] 1) Preparation of the layered titanate precursor: 2 g of potassium carbonate, 0.36 g of lithium carbonate, 5 g of titanium dioxide, and 20 g of potassium molybdate were mixed and ball-milled evenly, and then the obtained mixture powder was calcined at 1100 °C for 10 h to obtain layered titanic acid H 1.07 Ti 1.73 O 4 , with a length of about 100 μm and a thickness of about 1 μm.

[0029] 2) Preparation of the lithium extraction adsorbent: 0.5 g of layered titanic acid H 1.07 Ti 1.73 O 4 was added to 50 mL of 0.02 mol / L dimethylamine and reacted for 10 min to obtain titanium oxide nanosheets with accordion structure. During the suction filtration process, a large amount of water molecules in the accordion structure were lost, and then the nanosheets toppled from the vertical direction to obtain titanium oxide nanosheets with fish scale structure, with a length of about 100 μm and a thickness of about 10 nm. The accordion shape and fish scale shape before and after the structure toppling can be observed through an optical electron microscope.

[0030] 3) Adsorption experiment: 0.2 g of titanium oxide nanosheets with fish scale structure was placed in 20 mL of 20 mg / L LiCl solution and reacted at room temperature for 10 s. After the reaction, titanium oxide nanosheets with intercalated lithium ions in the interlayer were obtained, with a length of about 100 μm and a thickness of about 10 nm.

[0031] 4) Desorption experiment: The titanium oxide nanosheets with intercalated lithium ions in the interlayer were placed in 0.1 mol / L HCl and stirred for 30 min, and Li + was removed from the interlayer to obtain the shrunk layered titanic acid.

[0032] See Figure 1 , which is the optical microscope photo of the titanium oxide nanosheets with accordion structure prepared in Example 1. It can be clearly seen from the figure that before the reaction, the precursor is plate-shaped and has a small lateral size ( Figure 1 (a)), and after expansion ( Figure 1 (b)), the plate extends infinitely along the (010) crystal plane until it stabilizes, and titanium oxide nanosheets with a similar accordion structure are obtained.

[0033] See Figure 2 , which is the optical microscope photo of the titanium oxide nanosheets with fish scale structure prepared in Example 1. It can be clearly seen from the figure that the product after suction filtration and toppling is similar to a scale shape.

[0034] See Figure 3 , which is the optical microscope photograph of the lithium-ion intercalated accordion-structured titanium oxide nanosheets obtained from the adsorption experiment in Example 1. Compared with Figure 2 , after adsorbing lithium ions, the fish-scale structure transforms into the accordion structure again.

[0035] See Figure 4 , which is the optical microscope photograph of the lithium-ion desorption product obtained from the desorption experiment in Example 1. Compared with Figure 3 , it can be seen that after desorbing lithium ions, the accordion structure shrinks into layered titanic acid with a plate-like morphology.

[0036] From Figure 1 , Figure 2 , Figure 3 and Figure 4 as shown, it can be known that the titanium oxide nanosheets with a similar accordion structure (i.e., lithium extraction adsorbent), fish-scale structured titanium oxide nanosheets and the original layered titanic acid are reversibly transformable. Utilizing their reversible characteristics, the desorption and adsorption of lithium ions can be repeatedly realized.

[0037] Stability evaluation experiment: Repeat the above adsorption-desorption experiment 10 times. The experimental results show that the fish-scale structured titanium oxide nanosheets can still achieve efficient adsorption within 10 s after 10 times of desorption, proving its good cycle stability, and the adsorption capacity and adsorption rate remain unchanged.

[0038] Example 2

[0039] 1) Preparation of layered titanic acid precursor: Mix 2 g of potassium carbonate, 0.36 g of lithium carbonate, 5 g of titanium dioxide, and 20 g of potassium molybdate evenly by ball milling. Calcinate the obtained mixture powder at 900 °C for 10 h to obtain layered titanic acid H 1.07 Ti 1.73 O 4 . Immerse it in hydrogen peroxide solution to obtain layered titanic acid H 2 O 2 -H 1.07 Ti 1.73 O 4 , with a length of about 10 μm and a thickness of about 100 nm.

[0040] 2) Preparation of lithium extraction adsorbent: Take 0.5 g of layered titanic acid H 2 O 2 -H 1.07 Ti 1.73 O 4Add 50mL 0.02mol / L dimethylamine and react for 10 minutes to obtain accordion-structured titanium oxide nanosheets. During the filtration process, a large number of water molecules in the accordion structure are lost, and the sheets are collapsed from the vertical direction to obtain fish-scale-structured titanium oxide nanosheets, which are about 10μm long and 10nm thick. The accordion shape and fish-scale shape before and after the collapse of the structure can be observed by optical electron microscopy.

[0041] 3) Adsorption experiment: 0.2 g of fish-scale titanium oxide nanosheets was placed in 20 mL of 100 mg / L LiCl solution and reacted at room temperature for 10 s. After the reaction, accordion-structured titanium oxide nanosheets with interlayer lithium ions were obtained, which were about 10 μm in length and 10 nm in thickness.

[0042] 4) Desorption experiment: The accordion-structured titanium oxide nanosheets with interlayer lithium ions were placed in 0.1 mol / L HCl and stirred for 30 min. + It is released from between the layers to obtain a shrunken layered titanic acid.

[0043] The fish-scale structured titanium oxide nanosheets prepared in Example 2 also have the same reversible properties as those in Example 1, that is, the accordion structured titanium oxide nanosheets, the fish-scale structured titanium oxide nanosheets and the original layered titanic acid are reversibly transformed.

[0044] Stability evaluation experiment: The above adsorption-desorption experiment was repeated 10 times. The experimental results showed that after 10 desorption cycles, the fish-scale structured titanium oxide nanosheets could still achieve efficient adsorption within 10 seconds, proving that they have good cyclic stability.

[0045] Example 3

[0046] 1) Preparation of layered titanate precursor: 2.8 g potassium carbonate, 3.3 g ferric oxide, 5 g titanium dioxide, and 20 g potassium molybdate were mixed and ball-milled uniformly, and the obtained mixture powder was calcined at 1200 ° C for 24 h to obtain layered titanate H 0.8 Fe 0.8 Ti 1.2 O 4 , with a length of about 50 μm and a thickness of about 1 μm.

[0047] 2) Preparation of lithium-extracting adsorbent: 0.5 g of layered titanate H 0.8 Fe 0.8 Ti 1.2 O 4Add 50mL 0.02mol / L dimethylamine and react for 10 minutes to obtain accordion-structured titanium oxide nanosheets. During the filtration process, a large number of water molecules in the accordion structure are lost, and the sheets are collapsed from the vertical direction to obtain fish-scale-structured titanium oxide nanosheets, which are about 50μm long and 10nm thick. The accordion shape and fish-scale shape before and after the collapse of the structure can be observed by optical electron microscopy.

[0048] 3) Adsorption experiment: 0.2 g of fish-scale titanium oxide nanosheets was placed in 20 mL of 20 mg / L LiCl solution and reacted at room temperature for 10 s. After the reaction, accordion-structured titanium oxide nanosheets with interlayer lithium ions were obtained, which were about 50 μm in length and 10 nm in thickness.

[0049] 4) Desorption experiment: The accordion-structured titanium oxide nanosheets with interlayer lithium ions were placed in 0.1 mol / L HCl and stirred for 30 min. + It is released from between the layers to obtain a shrunken layered titanic acid.

[0050] The fish-scale structured titanium oxide nanosheets prepared in Example 3 also have the same reversible properties as those in Example 1, that is, the accordion structured titanium oxide nanosheets, the fish-scale structured titanium oxide nanosheets and the original layered titanic acid are reversibly transformed.

[0051] Stability evaluation experiment: The above adsorption-desorption experiment was repeated 10 times. The experimental results showed that after 10 desorption cycles, the fish-scale structured titanium oxide nanosheets could still achieve efficient adsorption within 10 seconds, proving that they have good cyclic stability.

[0052] In order to further demonstrate the beneficial technical effects of the present invention, the above examples were tested for adsorption performance. Figure 5 The adsorption rate curve of the breathing titanium oxide nanosheet is shown in FIG. 1 . It can be seen that the fish scale structure titanium oxide nanosheet can achieve complete and rapid adsorption of lithium ions within 10 seconds. The specific adsorption experiment is as follows: 0.2g of the fish scale structure titanium oxide nanosheet (Example 1 and Example 3) is placed in 20mL of 20mg / L and 100mg / L LiCl solutions, respectively, and reacted at room temperature for 10 seconds. After the reaction is completed, the product is filtered and the filtrate is collected. The initial 20mg / L LiCl and 100mg / L LiCl solutions and the Li+ in the filtrate are tested by ICP to detect the change in solution concentration before and after the reaction. Combined with the formula Q=(C 0 -C)*m / V (where Q is the adsorption capacity, C 0 is the Li in the starting solution + concentration, C is the Li + The adsorption capacity was calculated by using the adsorption capacity (m is the mass of adsorbent and V is the volume of initial solution).

[0053] Although the specific embodiments of the present invention have been described above, those skilled in the art should understand that these are only examples, and various changes or modifications can be made to this embodiment without departing from the principle and essence of the present invention. The protection scope of the present invention is only defined by the appended claims.

Claims

1. A method for preparing a lithium-extraction adsorbent based on breathable titanate nanosheets, characterized in that: Adding plate-like layered titanic acid into an ammonium solution, after standing, titanium oxide nanosheets with an accordion structure are obtained, and then drying and falling over, titanium oxide nanosheets with a fish scale structure are obtained, which are lithium extraction adsorbents; The structural formula of the layered titanic acid is H 0.8 Ti 2-x M x O4(x=0.4~0.8)、H 1.07 Ti 1.73 O4 or H2O2-H 1.07 Ti 1.73 O4, wherein M is selected from one of the elements Mg, Co, Ni, Cu, Zn, Mn(III), and Fe(III).

2. The method for preparing a lithium-extracting adsorbent based on breathable titanate nanosheets according to claim 1, characterized in that: The dosage ratio of titanic acid and ammonium solution is 0.2-1g:15-100mL.

3. The method for preparing a lithium-extracting adsorbent based on breathable titanate nanosheets according to claim 1, characterized in that: The ammonium solution is at least one of dimethylaminoethanol, tetrabutylammonium hydroxide, trimethylamine, dimethylethanolamine, 3-dimethylamino-1-propanol, and N,N-dimethylbutylamine solution.

4. The method for preparing a lithium-extracting adsorbent based on breathable titanate nanosheets according to claim 1, characterized in that: The static time is 30 minutes to 12 hours.

5. The method for preparing a lithium-extracting adsorbent based on breathable titanate nanosheets according to claim 1, characterized in that: The accordion-structured titanium oxide nanosheet has a length of 2 μm to 5 mm and a thickness of 2 to 200 nm.

6. A lithium extraction adsorbent, characterized in that: The method is prepared by any one of claims 1 to 5.

7. The use of the lithium extraction adsorbent according to claim 6, characterized in that: The fish-scale structured titanium oxide nanosheets are placed in a lithium ion solution to adsorb lithium ions and then transform into lithium ion intercalated accordion structured titanium oxide nanosheets. The lithium ion intercalated accordion structured titanium oxide nanosheets desorb lithium ions in an acid solution and then shrink to the original layered titanic acid.

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