Preparation method of micro-nano fiber aerogel aluminum-based lithium adsorbent
The preparation of micro/nanofiber aerogel aluminum-based lithium adsorbents through electrospinning technology has solved the problems of poor mechanical strength and insufficient active sites in the prior art, and achieved efficient adsorption performance and good mechanical properties.
Patent Information
- Application Number
- CN202411865636.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-18
- Publication Date
- 2025-06-20
AI Technical Summary
The existing aluminum-based lithium adsorbents have poor mechanical strength and insufficient active sites during the molding process, resulting in a decrease in adsorption performance, and difficulty in filling powders, poor permeability and difficulty in recycling.
Using electrospinning technology, a mixed solution of powder adsorbent, porogen, organic solvent and polymer is sprayed into fibers through the spinning nozzle to form a three-dimensional aerogel structure, and the roughness and porosity of the material surface are increased through the phase separation process initiated by double diffusion.
It significantly improves adsorption performance, enhances mechanical properties, reduces losses during circulation, and is simple to prepare, environmentally friendly, and has a wide range of applications.
Smart Images
Figure CN120169322A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of lithium adsorbents, and particularly relates to a preparation method of a micro / nano fiber aerogel aluminum-based lithium adsorbent. Background Art
[0002] Lithium, the lightest metal in nature, is known as the green energy metal and "white petroleum", and is widely used in the fields of energy storage, chemical industry, medicine, metallurgy, electronics industry, etc. With the rapid development of the lithium battery industry, the importance of lithium resources has become increasingly prominent. There are mainly two sources of lithium in the market. One is extracted from solid ore spodumene and lepidolite, and the other is extracted from lithium in water bodies, mainly from salt lake brines. The lithium resources in salt lake brines account for about 60% of the world's proven reserves. Compared with lithium ores, they have greater industrial value, and the extraction process is generally more economical and environmentally friendly.
[0003] The methods for extracting lithium from salt lakes mainly include precipitation method, electrochemical method, nanofiltration membrane method, extraction method and adsorption method. Compared with the other four lithium extraction methods, the adsorption method has the advantages of good selectivity, environmental friendliness, high adsorption capacity, easy recovery, simple preparation process and low cost, which makes the adsorption method one of the most widely used processes. At present, the adsorption method is mainly divided into three types of lithium adsorbents: aluminum-based, manganese-based and titanium-based. Among them, the aluminum-based lithium adsorbent, namely lithium / aluminum layered double hydroxide (Li / Al-LDH), has been proven to be suitable for extracting lithium from low-lithium grade brines with a very high Mg 2+ , + / Li + ratio. And because of its neutral desorption without dissolution damage, extremely low dissolution loss, stable cycle performance, and efficient adsorption / desorption process, it is the only successful industrial adsorbent at present. In the actual use process, the disadvantages of the powder adsorbent are fully exposed. It is difficult to load the powder adsorbent, and its permeability is poor during use, making it difficult to recover and resulting in a large loss of the powder adsorbent. Therefore, it is necessary to form and granulate the powder adsorbent to solve this problem. The adsorption performance of the granulated adsorbent will deteriorate because the binder used in the forming process will reduce the active sites of the adsorbent.
[0004] Compared with the prior art, the present invention provides a method for preparing a micro / nano fiber aerogel aluminum-based lithium adsorbent. By using the electrospinning technique, after a mixed solution obtained from a powder adsorbent, a pore-forming agent, an organic solvent, and a polymer is ejected as a spinning jet through a spinning nozzle, the spinning solution rapidly undergoes a phase separation process and is transformed into fibers. There is a Coulomb repulsion force between these fibers, so they are assembled and stacked into a three-dimensional aerogel structure. By controlling the phase separation induced by the double diffusion between the mixed solution and water vapor, the roughness and porosity of the material surface can be effectively increased, resulting in more reactive sites on the surface of the formed adsorbent, which can further improve the adsorption performance. Moreover, the prepared adsorbent has good mechanical properties, is simple to prepare, easy to recycle, has a wide application range, is green and environmentally friendly, and has good industrial prospects. Summary of the Invention
[0005] The purpose of the present invention is to provide a method for preparing a micro / nano fiber aerogel aluminum-based lithium adsorbent, aiming to solve the problems of poor mechanical strength and few active sites provided during adsorption in existing forming technologies, which lead to a significant decline in adsorption performance. The adsorbent prepared by the present invention not only has a stable structure and good adsorption performance, but also has extremely little loss during the cycling process and has broad application prospects.
[0006] The specific technical solution is as follows
[0007] A method for preparing a micro / nano fiber aerogel aluminum-based lithium adsorbent, the preparation principle of which is to carry out a coprecipitation reaction between a lithium-aluminum mixed solution and an alkali solution to form a precursor of the aluminum-based lithium adsorbent, mix the binder solution with the adsorbent precursor evenly, and assemble various components through the gel electrospinning technique to obtain a formed adsorbent.
[0008] It includes the following steps:
[0009] S1: Preparation of the precursor of the micro / nano fiber aerogel aluminum-based lithium adsorbent:
[0010] Dissolve a lithium source and an aluminum source in pure water to obtain a lithium-aluminum mixed solution, and then react the mixed solution with an alkali solution under stirring conditions. After aging for a period of time, finally obtain a precursor of the aluminum-based lithium adsorbent.
[0011] S2: Forming process:
[0012] (1) Add a polymer to an organic solvent, and after complete dissolution, form a binder solution;
[0013] (2) Disperse the precursor of the aluminum-based lithium adsorbent obtained in S1 and a pore-forming agent in the different binder solutions obtained in (1) to obtain multiple groups of mixed solutions with precursor substances;
[0014] (3) Arrange the multiple syringes filled with the precursor mixed solution obtained in S2 freely, and assemble them into a mold through the gel electrospinning technique. After curing, a molded adsorbent is obtained.
[0015] In some embodiments, the lithium source described in step S1 is selected from one or more of lithium chloride, lithium carbonate, lithium sulfate, and lithium hydroxide; the aluminum source is selected from one or more of hydrated aluminum chloride, anhydrous aluminum chloride, aluminum sulfate, hydrated aluminum sulfate, aluminum nitrate, and hydrated aluminum nitrate; the alkaline solution is one or more of sodium hydroxide, ammonia water, potassium hydroxide, and urea.
[0016] Preferably, the lithium source is lithium chloride, lithium sulfate, or lithium hydroxide; the aluminum source is hydrated aluminum chloride, aluminum sulfate, or hydrated aluminum nitrate; the alkaline solution is sodium hydroxide, potassium hydroxide, or urea.
[0017] In some embodiments, in step S1, the molar ratio of the addition amounts of the lithium source and the aluminum source is Li / Al = 1:(1 - 4), and the dropping rate of the alkaline solution is 2 - 50 ml / min;
[0018] Preferably, the dropping rate is 5 ml / min, 20 ml / min, or 40 ml / min.
[0019] In some embodiments of the preparation of the lithium-aluminum adsorbent precursor described in step S1, the concentration of the alkaline solution is 2 - 10 mol / L, the pH at the end of dropping is 4 - 8, the reaction temperature is 40 - 90 °C, the stirring speed is 100 - 300 r / min, and the aging time is 0 - 2 h.
[0020] Preferably, the speed is 100 r / min, 200 r / min, or 300 r / min; the pH is 4, 6, 7, or 8; the concentration is 4 mol / L, 6 mol / L, or 10 mol / L; the temperature is 40 °C, 60 °C, or 90 °C; the time is 0.5 h, 1 h, or 2 h;
[0021] In some embodiments, in step S2, (1) the polymer is selected from one of polymethyl methacrylate, polyvinyl chloride, polystyrene, polyacrylonitrile, polyurethane, polycarbonate, polyvinylidene fluoride, methyl cellulose, and polyethersulfone; the organic solvent is selected from one of N,N-dimethylformamide, N-methylpyrrolidone, acetone, ethyl acetate, tetrahydrofuran, chloroform, dimethyl sulfoxide, and N,N-dimethylacetamide.
[0022] Preferably, the polymer is polymethyl methacrylate, polyacrylonitrile, or polyethersulfone; the organic solvent is N,N-dimethylformamide, chloroform, or tetrahydrofuran.
[0023] In some of these embodiments, in step S2 (2), the ratio of the aluminum-based lithium adsorbent precursor, the pore-forming agent, and the binder solution is 1:(0.02 - 0.5):(5 - 20).
[0024] Preferably, the ratio is 1:0.02:5, 1:0.1:10, or 1:0.5:20.
[0025] In some of these embodiments, the pore-forming agent is selected from one or more of sodium chloride, surfactant, sodium bicarbonate, potassium chloride, polyethylene glycol - 6000, chitosan, polyvinyl alcohol, polyvinylpyrrolidone, and water-soluble starch.
[0026] Preferably, the pore-forming agent is sodium chloride, polyethylene glycol - 6000, or water-soluble starch.
[0027] In some of these embodiments, in step S2 (3), the feeding rate is 1 - 6 ml / h, the voltage applied to the electrode plate is 20 - 40 KV; the distance from the spinneret to the collector is 10 - 35 cm; the number of injectors is 1 - 4.
[0028] Preferably, the voltage is 20 KV, 30 KV, or 40 KV; the distance is 15 cm, 20 cm, or 25 cm;
[0029] The number of injectors is 2 or 3.
[0030] In some of these embodiments, in step S2 (3), the moving speed of the spinneret is 150 - 400 cm / min, the temperature of the electrospinning is 21 - 45 °C; the relative humidity is 25 - 95%.
[0031] Preferably, the moving speed is 200 cm / min, 250 cm / min, or 300 cm / min; the temperature is 21 °C, 30 °C, or 45 °C; the humidity is 30%, 50%, or 90%.
[0032] The present invention has the following advantages
[0033] (1) Excellent adsorption performance: Through the electrospinning technology and the phase separation process induced by double diffusion, the prepared micro / nano fiber aerogel aluminum-based lithium adsorbent has a high surface area and porosity, providing more reactive sites, thus significantly improving the adsorption performance and solving the problem of insufficient reactive sites in the prior art.
[0034] (2) Good mechanical properties and recyclability: The adsorbent prepared by the present invention has a stable structure, good mechanical properties, and very little loss during the recycling process. Moreover, the preparation process is simple and environmentally friendly, suitable for wide applications, and has good industrial prospects. Brief Description of the Drawings
[0035] Figure 1 This is the SEM image of the aluminum-based lithium adsorbent precursor prepared in Example 1 of the present invention.
[0036] Figure 2 This is the XRD patterns of the aluminum-based lithium adsorbent precursor and the formed particles prepared in Example 3 of the present invention. Detailed implementation manners
[0037] To more conveniently understand the technical implementation method of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the technical process steps, specific implementation conditions and materials in the embodiments of the present invention. Obviously, the described embodiments are only a 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 those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.
[0038] Example 1
[0039] 4.25 g of lithium chloride and 68.3 g of crystalline aluminum chloride were stirred at 50 °C until completely dissolved in 100 ml of water. 6 mol / L NaOH solution was added to the lithium-aluminum mixed solution at a dropping rate of 6 ml / min, and the end point pH was controlled to be 7. Then it was aged for 1 h. All processes were completed under stirring conditions, and the stirring speed was 300 r / min. The white mixed solution after the reaction was filtered, washed with water to remove part of the lithium, and then dried in a blast drying oven. After pulverization, the required aluminum-based lithium adsorbent precursor was obtained. Figure 1 This is its SEM micro-morphology image.
[0040] 4 g of polystyrene was dissolved in a mixed solution of 12 mL of N,N-dimethylformamide and 15 mL of tetrahydrofuran. After complete dissolution, 10 g of the adsorbent precursor and 0.5 g of sodium chloride were added to obtain Mixed Solution 1; in addition, 4 g of polyurethane was dissolved in 25 mL of N,N-dimethylformamide. After complete dissolution, 10 g of the adsorbent precursor and 0.5 g of sodium chloride were added to obtain Mixed Solution 2; then they were arranged in the order of Mixed Solution 1 - Mixed Solution 2 - Mixed Solution 1, and ejected through a spinneret. The feeding speed was 4 ml / h, the applied voltage was 30 KV, the distance from the spinneret to the collector was 20 cm, and the relative humidity of electrospinning was 85%. The ejected substance underwent phase transformation and then was recombined and cut into the required fibrous aerogel aluminum-based lithium adsorbent.
[0041] Example 2
[0042] 10.9 g of lithium sulfate and 72.4 g of crystalline aluminum chloride were stirred at 60 °C until completely dissolved in 100 ml of water. 6 mol / L NaOH solution was added to the lithium-aluminum mixed solution at a dropping rate of 8 ml / min, and the end point pH was controlled at 7. Then it was aged for 1 h. All processes were completed under stirring conditions, with a stirring speed of 300 r / min. The white mixed solution after the reaction was filtered, washed with water to remove part of the lithium, and then dried in a blast drying oven. After pulverization, the required aluminum-based lithium adsorbent precursor was obtained.
[0043] 4 g of polystyrene was dissolved in a mixed solution of 12 mL of N,N-dimethylformamide and 15 mL of tetrahydrofuran. After complete dissolution, 10 g of the adsorbent precursor and 0.5 g of potassium chloride were added to obtain mixed solution 1. Separately, 4 g of polyacrylonitrile was dissolved in 25 mL of N,N-dimethylformamide. After complete dissolution, 10 g of the adsorbent precursor and 0.5 g of sodium chloride were added to obtain mixed solution 2. Then, in the order of mixed solution 1 - mixed solution 2 - mixed solution 1, it was ejected through a spinneret, with a feeding speed of 4 ml / h, an applied voltage of 30 KV, a distance between the spinneret and the collector of 20 cm, and an electrospinning relative humidity of 85%. The ejected substance underwent phase transformation and was then recombined and pelletized into the required fibrous aerogel aluminum-based lithium adsorbent.
[0044] Example 3
[0045] 4.25 g of lithium chloride and 68.3 g of aluminum sulfate were stirred at 50 °C until completely dissolved in 100 ml of water. 4 mol / L NaOH solution was added to the lithium-aluminum mixed solution at a dropping rate of 6 ml / min, and the end point pH was controlled at 6. Then it was aged for 1 h. All processes were completed under stirring conditions, with a stirring speed of 300 r / min. The white mixed solution after the reaction was filtered, washed with water to remove part of the lithium, and then dried in a blast drying oven. After pulverization, the required aluminum-based lithium adsorbent precursor was obtained.
[0046] Dissolve 2 g of polymethyl methacrylate and 2 g of polyvinyl chloride in 26 mL of N,N-dimethylacetamide. After complete dissolution, add 10 g of adsorbent precursor and 1.5 g of sodium bicarbonate to obtain mixed solution 1; dissolve 4 g of polyurethane in 25 mL of N,N-dimethylformamide. After complete dissolution, add 10 g of adsorbent precursor and 0.5 g of sodium chloride to obtain mixed solution 2; finally, dissolve 4 g of polystyrene in a mixed solution of 25 mL of tetrahydrofuran and N,N-dimethylformamide. After complete dissolution, add 10 g of adsorbent precursor and 0.5 g of sodium chloride to obtain mixed solution 3. Then arrange them in the order of mixed solution 1 - mixed solution 2 - mixed solution 3 - mixed solution 1, spray them out through a spinneret, with a feeding speed of 4 ml / h, an applied voltage of 30 KV, a distance from the spinneret to the collector of 20 cm, and an electrospinning relative humidity of 60%. The ejected substance undergoes phase transformation and then recombination to obtain the required fibrous aerogel aluminum-based lithium adsorbent after pelletizing. Figure 2 XRD patterns of the prepared aluminum-based lithium adsorbent precursor and the formed particles.
[0048] Example 4
[0049] Stir 4.25 g of lithium chloride and 68.3 g of aluminum sulfate at 50 °C until completely dissolved in 100 ml of water. Add 4 mol / L NaOH solution to the lithium-aluminum mixed solution at a dropping speed of 6 ml / min, control the end point pH = 6, and then age for 1 h. All processes are completed under stirring conditions, with a stirring speed of 300 r / min. Filter the white mixed solution after the reaction, wash it with water to remove part of the lithium, and then dry it in a blast drying oven. After pulverization, the required aluminum-based lithium adsorbent precursor is obtained.
[0050] Dissolve 4 g of polycarbonate in a mixed solution of 12 mL of N,N-dimethylformamide and 15 mL of N-methylpyrrolidone. After complete dissolution, add 10 g of adsorbent precursor and 0.5 g of polyvinyl alcohol to obtain mixed solution 1; dissolve 4 g of polyvinylidene fluoride in 25 mL of N,N-dimethylformamide. After complete dissolution, add 10 g of adsorbent precursor and 0.5 g of polyvinyl alcohol to obtain mixed solution 2; then arrange them in the order of mixed solution 2 - mixed solution 1 - mixed solution 2, spray them out through a spinneret, with a feeding speed of 3 ml / h, an applied voltage of 20 KV, a distance from the spinneret to the collector of 25 cm, and an electrospinning relative humidity of 35%. The ejected substance undergoes phase transformation and then recombination to obtain the required fibrous aerogel aluminum-based lithium adsorbent after pelletizing.
[0051] Comparative Example 1
[0052] The difference from Example 1 is as follows: 4 g of polystyrene is dissolved in a mixed solution of 12 mL of N,N-dimethylformamide and 15 mL of tetrahydrofuran. After complete dissolution, 10 g of adsorbent precursor and 0.5 g of sodium chloride are added thereto to obtain a mixed solution. The mixed solution is ejected through a spinneret, the feeding rate is 4 ml / h, the applied voltage is 30 KV, the distance from the spinneret to the collector is 20 cm, the relative humidity for electrospinning is 85%, and the ejected substance undergoes phase inversion and then is recombined and pelletized to obtain an aluminum-based lithium adsorbent.
[0053] Comparative Example 2
[0054] 5 g of polyvinylidene fluoride and 1.5 g of potassium chloride are added to 35 ml of N-methylpyrrolidone. After being fully dissolved at high temperature, 16 g of the adsorbent precursor prepared in Example 2 is added. After the powder is uniformly dispersed in the solution, the mixed solution is dropped into water for curing, and the formed adsorbent is spherical.
[0055] Comparative Example 3
[0056] The aluminum-based lithium adsorbent precursor prepared in Example 1 is extruded into strips by a catalyst screw extruder, and granulated by water curing and removing water-soluble organic solvents. The adsorbent precursor, polymethyl methacrylate, polyvinyl chloride, and N,N-dimethylformamide are mixed according to a weight ratio of 1:0.21:0.21:1.3. The obtained dough is formed by an extruder and then pelletized to obtain a columnar adsorbent.
[0057] The aluminum-based lithium adsorbents after forming in Examples 1-4 and the aluminum-based adsorbents after forming in Comparative Examples 1-3 are subjected to static adsorption using the brine from Inca Huaxi. The compositions of the brine are shown in Table 1. The solid-liquid ratio during adsorption is 1 / 30, that is, 10 g of granular adsorbent is added to 300 ml of brine, and the adsorption time is 4 h. The adsorption capacity data of the above granular adsorbents are shown in Table 2.
[0058] Table 1. Compositions of each component in the brine
[0059]
[0060] Table 2. Adsorption capacities of several granular adsorbents
[0061]
[0062]
[0063] It can be seen from Table 2 that the granular aluminum-based adsorbents prepared by the methods of Examples 1-4 have higher adsorption performance than the adsorbents formed by traditional granulation. During the adsorption process, they can provide more adsorption active sites, which is beneficial to increasing the adsorption amount of the material in the brine.
[0064] Table 3 shows the mass loss rates of the formed aluminum-based lithium adsorbents in Examples 1-4 and the formed aluminum-based adsorbents in Comparative Examples 1-3 after 50 cycles.
[0065] Table 3. Mass Loss Rates of Several Particle Adsorbents after Cycling
[0066]
[0067] As can be seen from Table 3, the particulate aluminum-based adsorbents formed by the methods of Examples 1-4 have good mechanical properties, high cycle stability, and low pulverization degree.
[0068] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.
Claims
1. A method for preparing a micro / nano fiber aerogel aluminum-based lithium adsorbent, characterized in that: The lithium aluminum mixed solution is subjected to a co-precipitation reaction with an alkaline solution to form an aluminum-based lithium adsorbent precursor, the binder solution and the adsorbent precursor are evenly mixed, and the various components are assembled through gel electrospinning technology to obtain a formed adsorbent.
2. The method for preparing a micro / nano fiber aerogel aluminum-based lithium adsorbent according to claim 1, characterized in that: The following steps are involved: S1: Preparation of micro / nanofiber aerogel aluminum-based lithium adsorbent precursor: The lithium source and the aluminum source are dissolved in pure water to obtain a lithium-aluminum mixed solution, and then the mixed solution is subjected to a coprecipitation reaction with an alkaline solution under stirring conditions, and an aluminum-based lithium adsorbent precursor is finally obtained after an aging process; S2: Molding process: (1) Adding the polymer into an organic solvent and allowing it to completely dissolve to form a binder solution; (2) dispersing the aluminum-based lithium adsorbent precursor and porogen obtained in S1 in different binder solutions obtained in (1) to obtain multiple groups of mixed solutions containing precursor substances; (3) The multiple injectors filled with the precursor mixed solution obtained in S2 are freely arranged, assembled and formed by gel electrospinning technology, and then solidified to obtain a molded adsorbent.
3. The preparation method according to claim 1 or 2, characterized in that: The lithium source is selected from one or more of lithium chloride, lithium carbonate, lithium sulfate, and lithium hydroxide; the aluminum source is selected from one or more of hydrated aluminum chloride, anhydrous aluminum chloride, aluminum sulfate, hydrated aluminum sulfate, aluminum nitrate, and hydrated aluminum nitrate; the alkali solution is one or more of sodium hydroxide, ammonia water, potassium hydroxide, and urea.
4. The preparation method according to claim 1 or 2, characterized in that: The molar ratio of the lithium source and the aluminum source added is Li / Al=1:(1-4), and the alkali solution dropping speed is 2-50 ml / min.
5. The preparation method according to claim 1 or 2, characterized in that: The concentration of the alkali solution is 2-10 mol / L, the pH at the end point of the dropwise addition is 4-8, the reaction temperature is 40-90°C, the stirring speed is 100-300 r / min, and the aging time is 0-2h.
6. The preparation method according to claim 1 or 2, characterized in that: The organic solvent is selected from one of polymethyl methacrylate, polyvinyl chloride, polystyrene, polyacrylonitrile, polyurethane, polycarbonate, polyvinylidene fluoride, methyl cellulose and polyether sulfone; the organic solvent is selected from one or more of N,N-dimethylformamide, N-methylpyrrolidone, acetone, ethyl acetate, tetrahydrofuran, chloroform, dimethyl sulfoxide and N,N-dimethylacetamide.
7. The preparation method according to claim 2, characterized in that: In step S2 (2), the ratio of the aluminum-based lithium adsorbent precursor, the porogen and the binder solution is 1: (0.02-0.5): (5-20).
8. The preparation method according to claim 1 or 2, characterized in that: The porogen is selected from one or more of sodium chloride, surfactant, sodium bicarbonate, potassium chloride, polyethylene glycol-6000, chitosan, polyvinyl alcohol, polyvinyl pyrrolidone and water-soluble starch.
9. The preparation method according to claim 2, characterized in that: In step S2 (3), the feed rate is 1-6 ml / h, the voltage applied to the electrode plate is 20-40 KV; the distance from the spinneret to the collector is 10-35 cm; and the number of the sample injectors is 1-4.
10. The preparation method according to claim 2, characterized in that: The moving speed of the spinneret described in (3) in step S2 is 150-300 cm / min; the temperature of electrospinning is 21-45° C., and the relative humidity of electrospinning is 25-95%.