Method for improving stability and lithium adsorption capacity of lithium ion sieve Li1. 33Mn1. 67O4 through surface modification

Abstract

The invention belongs to the technical field of preparation of lithium ion sieves, and provides a method for improving the stability and lithium adsorption capacity of a lithium ion sieve Li < 1.33 > Mn < 1.67 > O < 4 > through surface modification in order to solve the problem that an existing lithium ion sieve H < 1.33 > Mn < 1.67 > O < 4 > is poor in stability. The preparation method comprises the following steps: mixing manganese carbonate MnCO3 and lithium carbonate Li2CO3 according to a Li / Mn molar ratio of 1.33: 1.67, and carrying out heat treatment in air at 500 DEG C for 4 hours to obtain lithium manganese oxide LMO; then mixing the LMO with a lithium nitrate LiNO3 solution, and finally calcining the obtained brown powder in air to prepare the lithium ion sieve precursor L-LMO. The internal stability of the lithium ion sieve is improved, and the lithium ion sieve has good low manganese dissolution loss and high adsorption rate and adsorption capacity. And the adsorption capacity in a lithium chloride solution with the initial concentration of 25 ppm can reach up to 32.55 mg / g.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium ion sieve preparation, and specifically relates to a surface modified lithium ion sieve Li 1.33 Mn 1.67 Methods for O4 stability and lithium adsorption capacity. Background Art

[0002] In recent years, lithium has been widely used in ceramics, glass, rechargeable lithium batteries, nuclear fusion fuels, energy storage materials and other fields. However, with the gradual increase in lithium demand, meeting the supply of lithium resources has become an important challenge. According to relevant research, lithium resources mainly come from ores, salt lake seawater and seawater. Among them, Li in seawater + The content is high, but the concentration is low. At the same time, seawater also contains a large amount of coexisting alkali metal ions (Na + , K + , Ca 2+ Mg 2+ ), which gives the extraction of Li + HMO-based lithium ion sieves have become one of the most popular lithium adsorbents due to their excellent lithium selectivity and high lithium adsorption capacity. + It shows excellent selectivity, but in the process of lithium extraction, there are some problems that restrict practical application, such as: more Mn dissolution during acid leaching; longer adsorption time; lower adsorption amount, etc. Summary of the invention

[0003] The present invention aims to solve the problem of existing lithium ion sieve H 1.33 Mn 1.67 O4 has poor stability, and provides a surface modification method to improve lithium ion screening Li 1.33 Mn 1.67 The method for adjusting the stability of O4 and the amount of lithium adsorption is provided. The present invention adopts a low-temperature hydrothermal method to regulate the intrinsic stability of the lithium ion sieve and constructs the sieve precursor L-HMO.

[0004] The present invention is realized by the following technical scheme: a surface modification method for improving lithium ion screening Li 1.33 Mn 1.67 The method for improving O4 stability and lithium adsorption capacity is as follows: manganese carbonate MnCO3 and lithium carbonate Li2CO3 are mixed at a Li / Mn molar ratio of 1.33:1.67, and then heat-treated in air at 500°C for 4 hours to obtain lithium manganese oxide LMO; then LMO is mixed with lithium nitrate LiNO3 solution, and finally the obtained brown powder is calcined in air to prepare a lithium ion sieve precursor L-LMO.

[0005] The specific steps include: (1) Preparation of lithium manganese oxide LMO: manganese carbonate MnCO3 and lithium carbonate Li2CO3 were mixed according to a Li / Mn molar ratio of 1.33:1.67, and heat-treated in air at 500°C for 4 hours to obtain lithium manganese oxide LMO; (2) dissolving lithium nitrate LiNO3 in deionized water, and then mixing 0.3 g-1.0 g of the lithium manganese oxide LMO obtained in step (1) with the lithium nitrate LiNO3 solution, wherein the molar ratio of LiNO3 to LMO is 2%-12%, and stirring in a 50-100°C water bath for 3-5 h to obtain a brown powder mixture, and heating the powder to 300-600°C at a rate of 4-5°C / min and calcining in air for 2-8 h to obtain a lithium ion sieve precursor L-LMO; (3) Preparation of L-HMO nanoparticles: The lithium ion sieve precursor L-LMO obtained in step (2) was acid-washed with 0.1-1.0M HCl solution for 24 h, washed with deionized water until the pH was neutral, and then the material was dried at 60° C. to prepare L-HMO nanoparticles.

[0006] The invention also provides L-HMO nanoparticles prepared by the method.

[0007] The present invention also provides an application of the L-HMO nanoparticles in lithium extraction from seawater, and the specific method is: preparing a lithium chloride solution with a pH of 7-10 and an initial concentration of 25 ppm, performing oscillation adsorption at a rotation speed of 150 rpm on a constant temperature shaker at 25°C, and measuring the lithium ion concentration in the solution at different times by an inductively coupled plasma emission spectrometer ICP-OES.

[0008] The method of the present invention prepares a lithium ion sieve with good stability, low manganese dissolution loss, high adsorption rate and high adsorption capacity. The present invention obtains a lithium ion sieve with good stability and studies the adsorption of Li from LiCl solution. + The results show that the unmodified lithium ion sieve H 1.33 Mn 1.67 Compared with O4, the modified lithium ion sieve Li-H 1.33 Mn 1.67 O4 has good low manganese dissolution loss, high adsorption rate and adsorption capacity. The adsorption capacity of the modified lithium ion sieve in the lithium chloride solution with an initial concentration of 25 ppm can be as high as 32.55 mg / g. The adsorption capacity of the unmodified lithium ion sieve is only 19.27 mg / g. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 is the SEM image of L-LMO and L-HMO nanoparticles; Figure 2 TEM image of L-LMO; Figure 3is the XRD spectra of HMO and L-HMO; Figure 4 XPS spectra before and after L-HMO adsorption; Figure 5 Li is the concentration of HMO and L-HMO in lithium chloride solutions at different pH values. + Adsorption capacity (C0 = 25 mg L -1 ; T = 25 ℃; t = 24h); Figure 6 This is the adsorption isotherm experiment of L-HMO; Figure 7 It is the adsorption kinetics experiment of HMO and L-HMO; Figure 8 The manganese dissolution loss and lithium adsorption amount of different lithium ion sieves. DETAILED DESCRIPTION

[0010] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all the embodiments; based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0011] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs, and the disclosure and materials cited therein are hereby incorporated by reference.

[0012] Technical equivalents to the specific embodiments described that are apparent to those skilled in the art using no more than routine experimentation are intended to be encompassed by this application.

[0013] The experimental methods in the following examples are all conventional methods unless otherwise specified. The instruments and equipment used in the following examples are all conventional laboratory instruments and equipment unless otherwise specified; the experimental materials used in the following examples are all purchased from conventional biochemical reagent stores unless otherwise specified.

[0014] Example 1: The preparation method of L-HMO particles for extracting lithium from seawater in this embodiment is as follows: manganese carbonate MnCO3 and lithium carbonate Li2CO3 are mixed in a specific molar ratio, and then heat-treated in high-temperature air to obtain lithium manganese oxide (LMO); then the mixture is immersed in a lithium nitrate solution to obtain a brown powder, and the powder is calcined at a high temperature to obtain a lithium ion sieve precursor L-LMO; the prepared L-LMO nanoparticles are immersed in an HCl solution, and then rinsed with deionized water to obtain a lithium ion sieve L-HMO.

[0015] The specific steps are as follows: (1) Li 1.33 Mn 1.67Preparation of O4: A mixture of manganese carbonate MnCO3 and lithium carbonate Li2CO3 was calcined in air at 450°C for 5 h at a Li / Mn molar ratio of 1.33:1.67 to prepare LMO powder; (2) Preparation of L-LMO nanoparticles: Lithium nitrate LiNO3 was dissolved in deionized water, and then 0.3 g-1.0 g of Li 1.33 Mn 1.67 O4 is mixed with lithium nitrate LiNO3 solution, in which the molar ratio of LiNO3 to LMO is 8%, and a brown powder mixture is obtained after stirring at 70 °C for 4 hours. The powder is calcined in air at 450 °C for 5 hours to obtain a new lithium manganese oxide L-LMO.

[0016] (3) Preparation of L-HMO nanoparticles: The lithium manganese oxide L-LMO obtained in step (2) was acid-washed with a 0.5 M HCl solution for 24 h, then washed with deionized water until the pH of the solution was neutral, and finally dried at 60° C. to obtain L-HMO nanoparticles; (4) Adsorption test: The lithium ion sieve adsorbent L-HMO nanoparticles prepared above were placed in a lithium chloride solution with a pH of 10 for adsorption, and the lithium ion adsorption amount was tested using ICP-OES.

[0017] The adsorption capacity of lithium ion sieve L-HMO in lithium chloride solution is excellent. When the initial concentration is 25 ppm at room temperature, the adsorption capacity of lithium ion sieve L-HMO is 32.55 mg / g, with excellent adsorption performance.

[0018] Example 2: The other aspects are the same as in Example 1, wherein the L-LMO nanoparticles are prepared as follows: lithium nitrate LiNO3 is dissolved in deionized water, and then 0.5 g of Li 1.33 Mn 1.67 O4 is mixed with lithium nitrate LiNO3 solution, wherein the molar ratio of LiNO3 to LMO is 2%, and a brown powder mixture is obtained after stirring at 50°C for 4 hours. The powder is calcined in air at 400°C for 6 hours to obtain new lithium manganese oxide L-LMO. In this embodiment, the adsorption amount of lithium ion sieve L-HMO reaches 22.57 mg / g.

[0019] Example 3: The rest is the same as Example 1, wherein the L-LMO nanoparticles are prepared as follows: lithium nitrate LiNO3 is dissolved in deionized water, and then 0.7 g of Li 1.33 Mn 1.67O4 is mixed with a certain amount of lithium nitrate LiNO3 solution, wherein the molar ratio of LiNO3 to LMO is 4%, and a brown powder mixture is obtained after stirring at 60 °C for 4 hours. The powder is calcined in air at 500 °C for 4 hours to obtain new lithium manganese oxide L-LMO. In this embodiment, the adsorption amount of lithium ion sieve L-HMO reaches 28.59 mg / g.

[0020] Example 4: The rest is the same as Example 1, wherein the L-LMO nanoparticles are prepared as follows: lithium nitrate LiNO3 is dissolved in deionized water, and then 0.9 g of Li 1.33 Mn 1.67 O4 is mixed with lithium nitrate LiNO3 solution, wherein the molar ratio of LiNO3 to LMO is 10%, and a brown powder mixture is obtained after stirring at 80°C for a period of time. The powder is calcined in air at 600°C for 3 hours to obtain new lithium manganese oxide L-LMO. In this embodiment, the adsorption amount of lithium ion sieve L-HMO reaches 27.41 mg / g.

[0021] The preparation conditions and adsorption amounts of Examples 1 to 4 are shown in Table 1.

[0022] Table 1 The composite material obtained in Example 1 was tested. Figure 1 Figure 2 is the SEM image of L-LMO and L-HMO. The results show that the diameter of the prepared L-LMO secondary microspheres is about 2 μm and is composed of many irregular LMO nanoparticles.

[0023] The composite material obtained in Example 1 was tested. Figure 2 TEM image of L-LMO prepared according to Example 1. It can be seen from the figure that the outer surface of L-LMO is covered by an amorphous layer with a thickness of about 3-5 nm, indicating that a metal oxide layer has been successfully grown on the surface of LMO. In addition, the coating can inhibit the dissolution of Mn by preventing direct contact between LMO particles and acidic solution, thereby improving the adsorption performance.

[0024] The composite material obtained in Example 1 was tested. Figure 3 The XRD spectra of HMO and L-HMO are shown in Figure 2. The lattice index can perfectly correspond to Li 1.33 Mn 1.67 O4 (JCPDS No. 89-0753) spinel structure, indicating that Li 1.33 Mn 1.67 The internal structure of the O4 material has not changed.

[0025] The composite material obtained in Example 1 was tested. Figure 4Figure 2 is the XPS spectra before and after L-HMO adsorption. Compared with before adsorption, a new peak appeared at 53.5 eV after adsorption, which can be attributed to the Li 1s peak of L-HMO, thus confirming that Li + Adsorbed on LIS.

[0026] The composite material obtained in Example 3 was tested. Figure 5 Li is the product of HMO and L-HMO in lithium chloride solutions at different pH values. + From the adsorption amount of L-HMO (C0=25 mg / L; T=25℃; t=24h; HMO), it can be clearly seen that the adsorption amount of lithium increases with the increase of pH value. Moreover, the adsorption amount of L-HMO is significantly higher than that of HMO in alkaline environment.

[0027] The composite material obtained in Example 3 was tested. Figure 6 L-HMO particles were immersed in LiCl solutions with initial concentrations of 0–150 mg / L. The equilibrium adsorption capacity (q e ) value gradually increases until it reaches a plateau, indicating that Li + The accessible adsorption sites on LIS are already saturated.

[0028] The composite material obtained in Example 3 was tested. Figure 7 Figure 2 shows the adsorption kinetics of HMO particles and L-HMO particles. For L-HMO nanoparticles, the adsorption equilibrium (29.25 mg / g) is reached in a very short time (12 h). The adsorption rate of HMO particles is slower, and the equilibrium state (19.27 mg / g) can be reached after 24 h. Compared with HMO particles, the adsorption rate of L-HMO is faster, which may be attributed to the appropriate surface area and pore size.

[0029] Except for the different molar ratios of LiNO3 and LMO, the rest was prepared according to Example 1. Figure 8 The manganese dissolution rate and adsorption amount of ion sieve of L-LMO made of different molar ratios of LiNO3 and LMO during the pickling process. It can be seen from the figure that the manganese dissolution loss of LMO during the pickling process is large, while L-HMO alleviates the dissolution loss of manganese ions.

[0030] Therefore, the research results show that the adsorption rate and adsorption amount of the modified L-HMO particles are better than those of the unmodified HMO particles, and the manganese dissolution loss of L-HMO during the pickling process is smaller and the adsorption rate is faster, so it has great application potential in seawater.

[0031] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A surface modification to improve lithium ion screening Li 1.33 Mn 1.67 The method for O4 stability and lithium adsorption is characterized by: Manganese carbonate MnCO3 and lithium carbonate Li2CO3 are mixed at a Li / Mn molar ratio of 1.33:1.67, and then heat-treated in air at 500°C for 4 hours to obtain lithium manganese oxide LMO; then LMO is mixed with lithium nitrate LiNO3 solution, and finally the obtained brown powder is calcined in air to prepare the lithium ion sieve precursor L-LMO.

2. The surface modification according to claim 1 improves the lithium ion sieve Li 1.33 Mn 1.67 The method for O4 stability and lithium adsorption is characterized by: The specific steps include: (1) Preparation of lithium manganese oxide LMO: manganese carbonate MnCO3 and lithium carbonate Li2CO3 were mixed according to a Li / Mn molar ratio of 1.33:1.67, and heat-treated in air at 500°C for 4 hours to obtain lithium manganese oxide LMO; (2) dissolving lithium nitrate LiNO3 in deionized water, and then mixing 0.3 g-1.0 g of the lithium manganese oxide LMO obtained in step (1) with the lithium nitrate LiNO3 solution, wherein the molar ratio of LiNO3 to LMO is 2%-12%, and stirring in a 50-100°C water bath for 3-5 hours to obtain a brown powder mixture, and heating the powder to 300-600°C at a rate of 4-5°C / min and calcining in air for 2-8 hours to obtain a lithium ion sieve precursor L-LMO; (3) Preparation of L-HMO nanoparticles: The lithium ion sieve precursor L-LMO obtained in step (2) was acid-washed with 0.1-1.0 M HCl solution for 24 h, washed with deionized water until the pH was neutral, and then the material was dried at 60° C. to prepare L-HMO nanoparticles.

3. L-HMO nanoparticles prepared by the method of claim 1 or 2.

4. The use of L-HMO nanoparticles in extracting lithium from seawater according to claim 3, characterized in that: The specific method is: prepare a lithium chloride solution with a pH of 7-10 and an initial concentration of 25 ppm, perform oscillation adsorption at a speed of 150 rpm in a constant temperature shaker at 25°C, and determine the lithium ion concentration in the solution at different times by inductively coupled plasma emission spectrometer ICP-OES.

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