A granular manganese-based adsorbent and its preparation method and application

Abstract

The present invention relates to the field of adsorbent technology, and in particular to a granular manganese-based adsorbent and its preparation method and application, comprising the following steps: adding polyvinyl chloride to N-N dimethylacetamide, stirring and dissolving, then adding porogen polyethylene glycol, dispersing evenly, then adding polyvinyl alcohol and manganese oxide ion sieve powder, mixing evenly, and obtaining a lithium ion sieve spherical particle precursor solution; adding a phase separator to the lithium ion sieve spherical particle precursor solution, solidifying to form spherical particles, completing phase separation by standing to obtain lithium ion sieve spherical particles; placing the lithium ion sieve spherical particles in a cross-linking agent for cross-linking, and obtaining a granular manganese-based adsorbent through post-processing. The adsorbent prepared by the present invention has a complete spherical structure, with a fine channel structure distributed on the surface, which is conducive to the exchange of lithium ions in the solution, has good adsorption performance for lithium ions, and has a low dissolution rate.

Description

Technical Field

[0001] The present invention relates to the technical field of adsorbents, and in particular to a granular manganese-based adsorbent and a preparation method and application thereof. Background Art

[0002] Lithium, with its physical and chemical properties such as high specific heat, high electrical conductivity, and strong chemical activity, is widely used in various fields of life and industrial production, such as glass, ceramics, chemicals, metallurgy, and the nuclear industry. Salt lake brines are rich in lithium resources and have important development value. Among the methods for extracting lithium from brines, adsorption methods are simple and environmentally friendly, making them a research hotspot in this area. The core focus is on developing adsorbents with high adsorption capacity and low dissolution rate. Industrial aluminum-based adsorbents have a low adsorption capacity of 1mg / g to 2mg / g, while industrial manganese-based adsorbents offer the advantages of high selectivity and high adsorption capacity, making them promising materials for extracting lithium from salt lake brines.

[0003] During the molding and granulation process of existing manganese-based adsorbents, in addition to bonding the powdered adsorbent in the organic solvent, a small amount of polymer will also enter the pores of the adsorbent, causing structural blockage, thereby reducing the contact area between the adsorbent and lithium ions, reducing the adsorption capacity and adsorption rate, and the adsorbent will suffer high dissolution loss during use. Summary of the Invention

[0004] To address the shortcomings of the prior art, the present invention provides a granular manganese-based adsorbent, its preparation method, and application. The present invention comprises dissolving polyvinyl chloride, polyvinyl alcohol, manganese oxide lithium ion sieve, and polyethylene glycol in a solvent (NN dimethylacetamide), separating the phases in deionized water, and then cross-linking the mixture in a glutaraldehyde solution to produce the granular manganese-based adsorbent. The adsorbent has a complete spherical structure with a finely divided surface channel structure, which facilitates lithium ion exchange in solution, exhibits excellent lithium ion adsorption, and exhibits a low dissolution loss rate.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A method for preparing a granular manganese-based adsorbent comprises the following steps:

[0007] Add polyvinyl chloride to NN dimethylacetamide, stir and dissolve, then add porogen polyethylene glycol and disperse evenly, then add polyvinyl alcohol and manganese oxide ion sieve powder, mix evenly to obtain a mixed solution.

[0008] A phase separation agent is added to the mixed solution, solidified to form spherical particles, and the phase separation is completed by standing to obtain lithium ion sieve spherical particles.

[0009] The lithium ion sieve spherical particles are placed in a cross-linking agent for cross-linking, and then post-treated to obtain a granular manganese-based adsorbent.

[0010] The present invention uses NN dimethylacetamide as a solvent, and adds polyvinyl alcohol and polyvinyl chloride thereto. Under the premise of ensuring the stability of the adsorbent structure, the dissolution loss problem caused by the high hydrophilicity of polyvinyl alcohol is reduced, and its hydrophilicity can be used to promote ion exchange and increase the adsorption capacity; polyvinyl alcohol and manganese oxide ion sieve powder are then added to form a lithium ion sieve spherical particle precursor solution, so that the internal space corridor of the sphere gradually decreases and the concave-convex structure gradually increases. This structure allows the solution to fully contact the adsorbent in the sphere through the corridor structure, which is conducive to improving the adsorption efficiency. After that, a phase separator is added to the lithium ion sieve spherical particle precursor powder, solidified to form spherical particles, and phase separation is completed by standing to obtain lithium ion sieve spherical particles. Finally, the lithium ion sieve spherical particles are placed in a cross-linking agent for cross-linking to obtain a granular manganese-based adsorbent. The granular manganese-based adsorbent prepared by the present invention has a complete spherical structure with a fine channel structure distributed on the surface, which is conducive to the exchange of lithium ions in the solution, has good adsorption performance for lithium ions, and has a low dissolution rate.

[0011] In a preferred embodiment of the present invention, the mass ratio of polyvinyl alcohol to polyvinyl chloride is 1:4-6, taking into account the adsorption performance and dissolution loss rate of the adsorbent. While ensuring the stability of the adsorbent structure, the dissolution loss caused by the high hydrophilicity of PVA is minimized, while at the same time utilizing its hydrophilicity to promote ion exchange and increase adsorption capacity.

[0012] In a preferred embodiment of the present invention, the mass ratio of manganese oxide ion sieve to polyvinyl chloride is 6-7:5. At this content, the internal spatial corridors of the sphere gradually decrease, while the concave-convex structure gradually increases. This structure allows the solution to fully contact the adsorbent in the sphere through the corridor structure, which is beneficial for improving adsorption efficiency. When the adsorbent content reaches 55%, the limited polymer can effectively encapsulate the adsorbent, reducing adsorbent loss.

[0013] In a preferred embodiment of the present invention, the manganese oxide ion sieve is Li 1.6 Mn 1.6 O4 ion sieve or Li4Mn5O 12 Ion sieve.

[0014] In a preferred embodiment of the present invention, the cross-linking agent is a glutaraldehyde acid solution, the volume concentration of the glutaraldehyde acid solution is 4.5% to 5.5%, and the usage ratio of the cross-linking agent to the manganese oxide ion sieve is 100 mL to 200 mL: 0.75 g.

[0015] In a preferred embodiment of the present invention, the cross-linking reaction temperature is 28° C. to 32° C., and the cross-linking time is 0.3 h to 0.7 h.

[0016] In a preferred embodiment of the present invention, the usage ratio of polyvinyl chloride to NN dimethylacetamide is 0.6 g: 5 mL to 10 mL.

[0017] In a preferred embodiment of the present invention, the diameter of the spherical particles formed by solidification is 2 mm to 3 mm, and the standing time is 1 h to 2 h.

[0018] Another object of the present invention is to provide a granular manganese-based adsorbent prepared by any of the preparation methods described above.

[0019] A third object of the present invention is to provide a use of the above-mentioned granular manganese-based adsorbent in the adsorption of lithium ions, wherein the adsorption capacity of the granular manganese-based adsorbent in a lithium standard solution with a concentration of 0.5 g / L is 21 mg / g to 23.43 mg / g, the lithium desorption rate is higher than 95%, and the dissolution loss rate of the adsorbent is 0.4% to 0.6%.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The present invention uses NN dimethylacetamide as a solvent, and adds polyvinyl alcohol and polyvinyl chloride thereto. Under the premise of ensuring the stability of the adsorbent structure, the dissolution loss problem caused by the high hydrophilicity of polyvinyl alcohol is reduced, and its hydrophilicity can be used to promote ion exchange and increase the adsorption capacity; polyvinyl alcohol and manganese oxide ion sieve powder are then added to form a lithium ion sieve spherical particle precursor solution, so that the internal space corridor of the sphere gradually decreases and the concave-convex structure gradually increases. This structure allows the solution to fully contact the adsorbent in the sphere through the corridor structure, which is conducive to improving the adsorption efficiency. After that, a phase separator is added to the lithium ion sieve spherical particle precursor powder, solidified to form spherical particles, and phase separation is completed by standing to obtain lithium ion sieve spherical particles. Finally, the lithium ion sieve spherical particles are placed in a crosslinking agent for crosslinking to obtain a granular manganese-based adsorbent. The granular manganese-based adsorbent prepared by the present invention has a complete spherical structure with a fine channel structure distributed on the surface, which is conducive to the exchange of lithium ions in the solution, has good adsorption performance for lithium ions, and has a low dissolution rate.

[0022] 2. The present invention uses NN dimethylacetamide as a solvent. NN dimethylacetamide can dissolve PVC evenly without agglomeration, has relatively low toxicity, and causes less pollution to the environment, which is more in line with environmental protection requirements. The crosslinking agent is a glutaraldehyde acid solution with a concentration of 4.5% to 5.5%. Compared with other concentrations of glutaraldehyde, this concentration range can reduce the dissolution loss of the adsorbent while ensuring adsorption performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 (a) to (c) are morphological images of the granular manganese-based adsorbent prepared in Example 1 at different magnifications.

[0024] Figure 2 In FIG. 1 , A is a graph showing the adsorption amount of the granular manganese-based adsorbents prepared in Examples 1 to 3, and B is a graph showing the lithium desorption rate and the adsorbent dissolution rate. DETAILED DESCRIPTION

[0025] The following is a detailed description of the technical solutions in the embodiments of the present invention, using preferred embodiments and accompanying drawings in conjunction with the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0026] It should be noted that all professional terms used in the present invention are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention. Unless otherwise specified, the various raw materials, reagents, instruments and equipment used in the following embodiments of the present invention can be purchased from the market or prepared by existing methods.

[0027] Example 1

[0028] A method for preparing a granular manganese-based lithium ion adsorbent comprises the following steps:

[0029] (1) Take 10 mL of NN-dimethylacetamide, slowly add 0.6 g of polyvinyl chloride, stir until it is evenly dissolved, add pore-forming agent polyethylene glycol PEG200 to make it evenly dispersed, then add 0.12 g of polyvinyl alcohol and 0.75 g of manganese oxide lithium ion sieve Li 1.6 Mn 1.6 O4, and stirred and mixed evenly to obtain a lithium ion sieve spherical particle precursor solution.

[0030] (2) Use a dropper to drop the lithium ion sieve spherical particle precursor solution into deionized water for phase separation, solidify to form spherical particles with a particle size of 2mm~3mm, and let it stand for 1.8h until the phase separation is completed, which is recorded as PCS.

[0031] (3) The separated PCS was placed in 200 mL of 5% glutaraldehyde 0.1 mol / L hydrochloric acid solution and cross-linked at 30°C for 0.5 h. After the cross-linking was completed, the PCS was taken out and washed with deionized water until neutral to prevent the acidic liquid from remaining on the surface of the sphere. Then, the PCS was placed in an oven at 40°C for drying and weighing. The PCS was sealed and allowed to stand for use to obtain a granular manganese-based lithium ion adsorbent.

[0032] The adsorption capacity of the granular manganese adsorbent prepared in Example 1 in a lithium standard solution with a concentration of 0.5 g / L was 23.43 mg / g, the lithium desorption rate was 96%, and the dissolution rate of the adsorbent was 0.5%. Figure 2 shown.

[0033] Example 2

[0034] A method for preparing a granular manganese-based lithium ion adsorbent comprises the following steps:

[0035] (1) Take 7 mL of NN-dimethylacetamide, slowly add 0.6 g of polyvinyl chloride, stir until it is evenly dissolved, add porogen polyethylene glycol PEG200 to make it evenly dispersed, then add 0.1 g of polyvinyl alcohol and 0.72 g of manganese oxide lithium ion sieve Li4Mn5O 12 After stirring and mixing evenly, a lithium ion sieve spherical particle precursor solution is obtained.

[0036] (2) Use a dropper to drop the lithium ion sieve spherical particle precursor solution into deionized water for phase separation, solidify to form spherical particles with a particle size of 2mm~3mm, and let it stand for 1.5h until the phase separation is completed, which is recorded as PCS.

[0037] (3) The separated PCS was placed in 150 mL of 4.5% glutaraldehyde 0.1 mol / L hydrochloric acid solution and cross-linked at 28°C for 0.3 h. After the cross-linking was completed, the PCS was taken out and washed with deionized water until neutral to prevent the acidic liquid from remaining on the surface of the sphere. The PCS was then placed in an oven at 40°C for drying and weighing. The PCS was sealed and allowed to stand for use to obtain a granular manganese-based lithium ion adsorbent.

[0038] The adsorption capacity of the granular manganese adsorbent prepared in Example 2 in a lithium standard solution with a concentration of 0.5 g / L was 21 mg / g, the lithium desorption rate was 95%, and the dissolution rate of the adsorbent was 0.4%. Figure 2 shown.

[0039] Example 3

[0040] A method for preparing a granular manganese-based lithium ion adsorbent comprises the following steps:

[0041] (1) Take 5 mL of NN-dimethylacetamide, slowly add 0.6 g of polyvinyl chloride, stir until it is evenly dissolved, add pore-forming agent polyethylene glycol PEG200 to make it evenly dispersed, then add 0.15 g of polyvinyl alcohol and 0.8 g of manganese oxide lithium ion sieve Li 1.6 Mn 1.6 O4, and stirred and mixed evenly to obtain a lithium ion sieve spherical particle precursor solution.

[0042] (2) Use a dropper to drop the lithium ion sieve spherical particle precursor solution into deionized water for phase separation, solidify to form spherical particles with a particle size of 2mm~3mm, and let it stand for 2h until the phase separation is completed, which is recorded as PCS.

[0043] (3) The separated PCS was placed in 100 mL of 5.5% glutaraldehyde 0.1 mol / L hydrochloric acid solution and cross-linked at 32°C for 0.7 h. After the cross-linking was completed, the PCS was taken out and washed with deionized water until neutral to prevent the acidic liquid from remaining on the surface of the sphere. Then, the PCS was placed in an oven at 40°C for drying and weighing. The PCS was sealed and allowed to stand for use to obtain a granular manganese-based lithium ion adsorbent.

[0044] The adsorption capacity of the granular manganese-based adsorbent prepared in Example 3 in a lithium standard solution with a concentration of 0.5 g / L was 22.5 mg / g, the lithium desorption rate was 98%, and the dissolution rate of the adsorbent was 0.6%. Figure 2 shown.

[0045] Result Analysis

[0046] Figure 1 This is a morphology of the granular manganese-based adsorbent prepared in Example 1. Figure (a) shows that the adsorbent has a complete spherical structure, with good encapsulation of the ion sieve powder. Magnification of 1000x (Figure (b)) reveals the presence of fine, evenly distributed channels on the adsorbent surface. Magnification of 5000x (Figure (c)) reveals the adsorbent's compact structure, well-connected pores, and minimal disconnection. This structure facilitates lithium ion exchange in solution. The results demonstrate high lithium ion exchange efficiency, rapid adsorption, and excellent performance in solution.

[0047] In summary, the present invention uses NN dimethylacetamide as a solvent, adds polyvinyl alcohol and polyvinyl chloride thereto, and reduces the dissolution loss problem caused by the high hydrophilicity of polyvinyl alcohol while ensuring the stability of the adsorbent structure. At the same time, its hydrophilicity can be used to promote ion exchange and increase the adsorption capacity; polyvinyl alcohol and manganese oxide ion sieve powder are then added to form a lithium ion sieve spherical particle precursor solution, so that the internal space corridor of the sphere gradually decreases and the concave-convex structure gradually increases. This structure allows the solution to fully contact the adsorbent in the sphere through the corridor structure, which is beneficial to improving the adsorption efficiency. After that, a phase separator is added to the lithium ion sieve spherical particle precursor powder, solidified to form spherical particles, and phase separation is completed by standing to obtain lithium ion sieve spherical particles. Finally, the lithium ion sieve spherical particles are placed in a cross-linking agent for cross-linking to obtain a granular manganese-based adsorbent. The granular manganese-based adsorbent prepared by the present invention has a complete spherical structure with a fine channel structure distributed on the surface, which is beneficial to the exchange of lithium ions in the solution, has good adsorption performance for lithium ions, and has a low dissolution rate.

[0048] It should be noted that when the present invention relates to numerical ranges, it should be understood that both endpoints of each numerical range and any value between the two endpoints can be selected. Since the steps and methods used are the same as those in the embodiments, in order to avoid redundancy, the present invention describes the preferred embodiments. Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they understand the basic inventive concepts. Therefore, the attached protection scope is intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0049] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the present invention and its equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A method for preparing a granular manganese-based adsorbent for reducing the dissolution loss rate of the adsorbent, characterized in that: The following steps are involved: Add polyvinyl chloride to N,N-dimethylacetamide and stir to dissolve, then add porogen polyethylene glycol and disperse evenly, then add polyvinyl alcohol and manganese oxide ion sieve powder and mix evenly to obtain a lithium ion sieve spherical particle precursor solution; wherein the mass ratio of polyvinyl alcohol to polyvinyl chloride is 1:4-6; Adding a phase separation agent to the lithium ion sieve spherical particle precursor solution, solidifying to form spherical particles, and completing phase separation by standing to obtain lithium ion sieve spherical particles; placing the lithium ion sieve spherical particles in a cross-linking agent for cross-linking, and performing post-treatment to obtain a granular manganese-based adsorbent; The mass ratio of manganese oxide ion sieve to polyvinyl chloride is 6~7:5; The cross-linking agent is a glutaraldehyde acid solution, and the volume concentration of the glutaraldehyde acid solution is 4.5% to 5.5%.

2. The method for preparing a granular manganese-based adsorbent according to claim 1, wherein: Manganese oxide ion sieve for Li 1.6 Mn 1.6 O4 ion sieve or Li4Mn5O 12 Ion sieve.

3. The method for preparing a granular manganese-based adsorbent according to claim 1, wherein: The usage ratio of the cross-linking agent to the manganese oxide ion sieve is 100 mL~200 mL: 0.75 g.

4. The method for preparing a granular manganese-based adsorbent according to claim 1, wherein: The cross-linking reaction temperature is 28°C~32°C, and the cross-linking time is 0.3h~0.7h.

5. The method for preparing a granular manganese-based adsorbent according to claim 1, wherein: The usage ratio of polyvinyl chloride and N,N-dimethylacetamide is 0.6g:5mL~10mL.

6. The method for preparing a granular manganese-based adsorbent according to claim 1, wherein: The diameter of the spherical particles formed by solidification is 2mm~3mm, and the standing time is 1h~2h.

7. A granular manganese-based adsorbent prepared by the preparation method according to any one of claims 1 to 6.

8. Use of the granular manganese-based adsorbent according to claim 7 in adsorbing lithium ions.

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