Granular manganese adsorbent as well as preparation method and application thereof

Abstract

The invention relates to the technical field of adsorbents, in particular to a granular manganese adsorbent and a preparation method and application thereof.The preparation method comprises the following steps that polyvinyl chloride is added into N-N dimethylacetamide and stirred to be dissolved, then a pore-foaming agent polyethylene glycol is added and evenly dispersed, then polyvinyl alcohol and manganese oxide ion sieve powder are added and evenly mixed, and the granular manganese adsorbent is obtained; a lithium ion sieve spherical particle precursor solution is obtained; adding a phase splitting agent into the lithium ion sieve spherical particle precursor solution, curing to form spherical particles, and standing to complete phase splitting to obtain lithium ion sieve spherical particles; and putting the lithium ion sieve spherical particles into a cross-linking agent for cross-linking, and carrying out post-treatment to obtain the granular manganese adsorbent. The prepared adsorbent has a complete sphere structure, fine channel structures are distributed on the surface, exchange of lithium ions in a solution is facilitated, the adsorption performance on the lithium ions is good, and the dissolution loss rate is low.

Description

Technical Field

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

[0002] Lithium has physical and chemical properties such as high specific heat, high electrical conductivity and strong chemical activity, and is widely used in various fields of life and industrial production, such as glass, ceramics, chemical industry, metallurgy, nuclear industry, etc. The lithium resources in salt lake brine are rich and have important development value. Among the methods for extracting lithium from brine, the adsorption method has simple process and is environmentally friendly, becoming a research hotspot in the aspect of extracting lithium from brine. The core is to develop an adsorbent with high adsorption capacity and low dissolution loss rate. The industrial aluminum-based adsorbent has a small adsorption capacity, between 1mg / g and 2mg / g, while the industrial manganese-based adsorbent has the advantages of high selectivity and high adsorption capacity, making it a promising material for extracting lithium from salt lake brine.

[0003] In the process of forming and granulating the existing manganese-based adsorbent, in addition to binding the powder adsorbent, a small amount of the high polymer will enter the interior of the pores of the adsorbent in the organic solvent, causing structural blockage, thereby reducing the contact area between the adsorbent and lithium ions, decreasing the adsorption capacity and adsorption rate, and having a high dissolution loss during the use of the adsorbent. Summary of the Invention

[0004] Aiming at the above deficiencies of the prior art, the purpose of the present invention is to provide a granular manganese-based adsorbent, a preparation method thereof and an application thereof. In the present invention, polyvinyl chloride, polyvinyl alcohol, manganese oxide lithium sieve and polyethylene glycol are dissolved in the solvent N-N dimethylacetamide, phase separation is carried out in deionized water, and then crosslinking is carried out in a glutaraldehyde solution to obtain a granular manganese-based adsorbent. This adsorbent has a complete spherical structure, and a fine channel structure is 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 loss rate.

[0005] To solve the above technical problems, the present invention adopts the following technical solutions: A preparation method of a granular manganese-based adsorbent, comprising the following steps: Add polyvinyl chloride to N-N dimethylacetamide, stir and dissolve, then add the pore-forming agent polyethylene glycol, disperse evenly, and then add polyvinyl alcohol and manganese oxide lithium sieve powder, and mix evenly to obtain a mixed solution.

[0006] Add a phase separation agent to the mixed solution, solidify to form spherical particles, and complete phase separation by standing to obtain spherical lithium sieve particles.

[0007] Place the spherical lithium sieve particles in a crosslinking agent for crosslinking, and after post-treatment, obtain a granular manganese-based adsorbent.

[0008] The present invention uses N-N 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 stable structure of the adsorbent. At the same time, it can utilize its hydrophilic property to promote ion exchange and increase the adsorption capacity. Then, polyvinyl alcohol and manganese oxide sieve powder are added to form a precursor solution of spherical lithium ion sieve particles, which gradually reduces the internal space corridors of the spheres and increases the concave-convex structures. This structure enables the solution to fully contact the adsorbent in the spheres through the corridor structure, which is beneficial to improving the adsorption efficiency. After that, a phase separation agent is added to the precursor powder of spherical lithium ion sieve particles, and spherical particles are formed by curing. Phase separation is completed by standing to obtain spherical lithium ion sieve particles. Finally, the spherical lithium ion sieve particles are placed in a crosslinking agent for crosslinking to obtain granular manganese-based adsorbents. The granular manganese-based adsorbents prepared by the present invention have a complete spherical structure, and a fine channel structure is distributed on the surface, which is beneficial to the exchange of lithium ions in the solution, has good adsorption performance for lithium ions, and a low dissolution loss rate.

[0009] In a preferred embodiment of the present invention, the mass ratio of polyvinyl alcohol to polyvinyl chloride is 1:4 - 6, comprehensively considering the adsorption performance and dissolution loss rate of the adsorbent. On the premise of ensuring the stable structure of the adsorbent, the dissolution loss problem caused by the high hydrophilicity of PVA is minimized as much as possible. At the same time, its hydrophilic property can be utilized to promote ion exchange and increase the adsorption capacity.

[0010] In a preferred embodiment of the present invention, the mass ratio of manganese oxide sieve to polyvinyl chloride is 6 - 7:5. At this content, the internal space corridors of the spheres gradually decrease, and the concave-convex structures gradually increase. This structure enables the solution to fully contact the adsorbent in the spheres through the corridor structure, which is beneficial to improving the adsorption efficiency. When the adsorbent content is 55%, the limited polymer can better wrap the adsorbent and reduce the loss of the adsorbent.

[0011] In a preferred embodiment of the present invention, the manganese oxide sieve is Li 1.6 Mn 1.6 O4 ion sieve or Li4Mn5O 12 ion sieve.

[0012] In a preferred embodiment of the present invention, the crosslinking agent is glutaraldehyde acidic solution, the volume concentration of the glutaraldehyde acidic solution is 4.5% - 5.5%, and the dosage ratio of the crosslinking agent to the manganese oxide sieve is 100 mL - 200 mL:0.75 g.

[0013] In a preferred embodiment of the present invention, the crosslinking reaction temperature is 28°C - 32°C, and the crosslinking time is 0.3 h - 0.7 h.

[0014] In a preferred embodiment of the present invention, the dosage ratio of polyvinyl chloride to N-N dimethylacetamide is 0.6 g:5 mL - 10 mL.

[0015] In a preferred embodiment of the present invention, the diameter of the spherical particles formed by curing is 2 mm to 3 mm, and the standing time is 1 h to 2 h.

[0016] Another object of the present invention is to provide a granular manganese-based adsorbent prepared by the preparation method described in any one of the above.

[0017] The third object of the present invention is to provide an application of the granular manganese-based adsorbent described above in adsorbing lithium ions. 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 desorption rate of lithium is higher than 95%, and the dissolution loss rate of the adsorbent is 0.4% to 0.6%.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. The present invention uses N,N-dimethylacetamide as a solvent, and adds polyvinyl alcohol and polyvinyl chloride thereto. On the premise of ensuring the stable structure of the adsorbent, the dissolution loss problem caused by the high hydrophilicity of polyvinyl alcohol is reduced, and at the same time, its hydrophilic property can be utilized to promote ion exchange and improve the adsorption capacity; then polyvinyl alcohol and manganese oxide sieve powder are added to form a precursor solution of lithium ion sieve spherical particles, so that the internal space corridors of the spheres gradually decrease and the concave-convex structure gradually increases. This structure enables the solution to fully contact the adsorbent in the spheres through the corridor structure, which is beneficial to improving the adsorption efficiency. After that, a phase separation agent is added to the precursor powder of the lithium ion sieve spherical particles to cure and 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, and a delicate channel structure is distributed on the surface, which is beneficial to the exchange of lithium ions in the solution, has good adsorption performance for lithium ions, and a low dissolution loss rate.

[0019] 2. The present invention selects N,N-dimethylacetamide as a solvent. N,N-dimethylacetamide can uniformly dissolve PVC without agglomeration, and has relatively low toxicity and less environmental pollution, which better meets the environmental protection requirements. The cross-linking agent is a glutaraldehyde acidic solution with a concentration of 4.5% to 5.5%. Compared with glutaraldehyde with other concentrations, the concentration in this range can make the dissolution loss of the adsorbent smaller on the premise of ensuring the adsorption performance. Description of the Drawings

[0020] Figure 1 Among them, (a) to (c) are morphology diagrams of the granular manganese-based adsorbent prepared in Example 1 at different magnification multiples.

[0021] Figure 2 Among them, A is the adsorption capacity result diagram of the granular manganese-based adsorbent prepared in Examples 1 to 3, and B is the lithium desorption rate and adsorbent dissolution loss rate result diagram. Detailed implementation mode

[0022] The following combines the embodiments of the present invention, and uses preferred embodiments and accompanying drawings for detailed description. The technical solutions in the embodiments of the present invention are clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0023] It should be noted that all the professional terms used in the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the protection scope of the present invention. Unless otherwise specifically stated, various raw materials, reagents, instruments and equipment used in the following embodiments of the present invention can be obtained through the market or prepared by existing methods.

[0024] Example 1 A preparation method of granular manganese-based lithium ion adsorbent includes the following steps: (1) Take 10 mL of N-N dimethylacetamide, slowly add 0.6 g of polyvinyl chloride, stir until it is uniformly dissolved, add the pore-forming agent polyethylene glycol PEG200 to make it uniformly dispersed, and 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. After stirring and mixing evenly, a precursor solution of lithium ion sieve spherical particles is obtained.

[0025] (2) Use a dropper to drop the precursor solution of lithium ion sieve spherical particles into deionized water for phase separation, solidify to form spherical particles with a particle size of 2 mm to 3 mm, and let it stand for 1.8 h until the phase separation is completed, denoted as PCS.

[0026] (3) Place the phase-separated PCS in 200 mL of a 5% glutaraldehyde 0.1 mol / L hydrochloric acid solution, crosslink at 30 °C for 0.5 h. After the crosslinking is completed, take it out and wash it with deionized water until it is neutral to prevent residual acidic liquid on the surface of the sphere. Then put it in an oven at 40 °C to dry and weigh, seal and let it stand for use to obtain a granular manganese-based lithium ion adsorbent.

[0027] The adsorption capacity of the granular manganese-based adsorbent prepared in Example 1 in a lithium standard solution with a concentration of 0.5 g / L is 23.43 mg / g, the desorption rate of lithium is 96%, and the dissolution loss rate of the adsorbent is 0.5%. The results are as Figure 2 shown.

[0028] Example 2 A preparation method of granular manganese-based lithium ion adsorbent includes the following steps: (1) Take 7 mL of N-N dimethylacetamide, slowly add 0.6 g of polyvinyl chloride, stir until it is uniformly dissolved, add the pore-forming agent polyethylene glycol PEG200 to make it uniformly dispersed, and then add 0.1 g of polyvinyl alcohol and 0.72 g of manganese oxide lithium sieve Li4Mn5O 12 , and after stirring and mixing evenly, a precursor solution of spherical particles of lithium sieve is obtained.

[0029] (2) Use a dropper to drop the precursor solution of spherical particles of lithium sieve into deionized water for phase separation, solidify to form spherical particles with a particle size of 2 mm to 3 mm, and let it stand for 1.5 h until the phase separation is completed, denoted as PCS.

[0030] (3) Place the phase-separated PCS in 150 mL of a hydrochloric acid solution containing 4.5% glutaraldehyde at 0.1 mol / L, crosslink at 28 °C for 0.3 h, take it out after crosslinking and wash it with deionized water until neutral to prevent residual acidic liquid on the surface of the sphere, then put it in an oven at 40 °C to dry and weigh, seal and let it stand for use, and obtain granular manganese-based lithium ion adsorbent.

[0031] The adsorption capacity of the granular manganese-based adsorbent prepared in Example 2 in a lithium standard solution with a concentration of 0.5 g / L is 21 mg / g, the desorption rate of lithium is 95%, and the dissolution loss rate of the adsorbent is 0.4%. The results are as Figure 2 shown.

[0032] Example 3 A preparation method of a granular manganese-based lithium ion adsorbent, comprising the following steps: (1) Take 5 mL of N-N dimethylacetamide, slowly add 0.6 g of polyvinyl chloride, stir until it is uniformly dissolved, add the pore-forming agent polyethylene glycol PEG200 to make it uniformly dispersed, and then add 0.15 g of polyvinyl alcohol and 0.8 g of manganese oxide lithium sieve Li 1.6 Mn 1.6 O4, and after stirring and mixing evenly, a precursor solution of spherical particles of lithium sieve is obtained.

[0033] (2) Use a dropper to drop the precursor solution of spherical particles of lithium sieve into deionized water for phase separation, solidify to form spherical particles with a particle size of 2 mm to 3 mm, and let it stand for 2 h until the phase separation is completed, denoted as PCS.

[0034] (3) Place the phase-separated PCS in 100 mL of a hydrochloric acid solution containing 5.5% glutaraldehyde at 0.1 mol / L, crosslink at 32 °C for 0.7 h, take it out after crosslinking and wash it with deionized water until neutral to prevent residual acidic liquid on the surface of the sphere, then put it in an oven at 40 °C to dry and weigh, seal and let it stand for use, and obtain granular manganese-based lithium ion adsorbent.

[0035] 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 desorption rate of lithium was 98%, and the dissolution loss rate of the adsorbent was 0.6%. The results are as Figure 2 shown.

[0036] Result analysis Figure 1 FIG. 8 is a morphology diagram of the granular manganese-based adsorbent prepared in Example 1. It can be seen from FIG. (a) that the adsorbent has a complete spherical structure and the ion sieve powder is well embedded. Magnifying to 1000 times (FIG. (b)) for observation, it can be seen that there are delicate channel structures on the surface of the adsorbent and they are evenly distributed. Through 5000 times (FIG. (c)), it can be seen that the structure of the adsorbent is compact, the pore channel structures are well connected, and there are few disconnection phenomena. This structure is beneficial to the exchange of lithium ions in the solution. The results show that the adsorbent has a high lithium ion exchange efficiency, a fast adsorption rate and good performance in the solution.

[0037] In summary, in the present invention, N,N-dimethylacetamide is used as a solvent, polyvinyl alcohol and polyvinyl chloride are added thereto. On the premise of ensuring the structural stability of the adsorbent, the dissolution loss problem caused by the high hydrophilicity of polyvinyl alcohol is reduced, and at the same time, its hydrophilic property can be utilized to promote ion exchange and increase the adsorption capacity; then polyvinyl alcohol and manganese oxide ion sieve powder are added to form a precursor solution of spherical lithium ion sieve particles, so that the internal space corridors of the spheres gradually decrease and the concave-convex structures gradually increase. This structure enables the solution to fully contact the adsorbent in the spheres through the corridor structure, which is beneficial to improving the adsorption efficiency. Then, a phase separation agent is added to the precursor powder of the spherical lithium ion sieve particles, and spherical particles are formed by curing. Phase separation is completed by standing to obtain spherical lithium ion sieve particles. Finally, the spherical lithium ion sieve 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, and delicate channel structures are 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 loss rate.

[0038] It should be noted that when the present invention involves 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 adopted step methods are the same as those in the examples, in order to prevent repetition, the present invention describes the preferred embodiments. Although the preferred embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications to these embodiments once they know the basic creative concept. Therefore, the scope of protection attached is intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present invention.

[0039] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the present invention and the scope of equivalent technologies thereof, the present invention also intends to include these changes and modifications therein.

Claims

1. A preparation method of a granular manganese-based adsorbent, characterized in that, It includes the following steps: Add polyvinyl chloride into N-N dimethylacetamide, stir and dissolve it. Then add the pore-forming agent polyethylene glycol and disperse it evenly. Next, add polyvinyl alcohol and manganese oxide sieve powder and mix them evenly to obtain a precursor solution of spherical lithium-ion sieve particles. Among them, the mass ratio of polyvinyl alcohol to polyvinyl chloride is 1:4 - 6; Add a phase separation agent to the precursor solution of spherical lithium-ion sieve particles, solidify to form spherical particles, and complete phase separation by standing to obtain spherical lithium-ion sieve particles; Place the spherical lithium-ion sieve particles in a cross-linking agent for cross-linking, and after post-treatment, obtain granular manganese-based adsorbents.

2. The preparation method of the granular manganese-based adsorbent according to claim 1, characterized in that, The mass ratio of manganese oxide sieve to polyvinyl chloride is 6 - 7:

5.

3. The preparation method of the granular manganese-based adsorbent according to claim 1, characterized in that, Manganese oxygen ion sieve is Li 1.6 Mn 1.6 O4 ion sieve or Li4Mn5O 12 ion sieve.

4. The preparation method of the granular manganese-based adsorbent according to claim 1, characterized in that, The cross-linking agent is a glutaraldehyde acidic solution, the volume concentration of the glutaraldehyde acidic solution is 4.5% - 5.5%, and the dosage ratio of the cross-linking agent to the manganese oxide sieve is 100 mL - 200 mL:0.75 g.

5. The preparation method of the granular manganese-based adsorbent according to claim 1, characterized in that, The cross-linking reaction temperature is 28°C - 32°C, and the cross-linking time is 0.3 h - 0.7 h.

6. The preparation method of the granular manganese-based adsorbent according to claim 1, characterized in that, The dosage ratio of polyvinyl chloride to N-N dimethylacetamide is 0.6 g:5 mL - 10 mL.

7. The preparation method of the granular manganese-based adsorbent according to claim 1, characterized in that, The diameter of the spherical particles formed by solidification is 2 mm - 3 mm, and the standing time is 1 h - 2 h.

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

9. An application of the granular manganese-based adsorbent according to claim 8 in adsorbing lithium ions.

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