A lithium extraction adsorbent, a preparation method and application thereof

Abstract

The application provides a lithium extraction adsorbent and a preparation method and application thereof, and the preparation method comprises the following steps: (1) mixing an aluminum salt and lithium chloride with a solvent, adding an alkali liquor for one-step reaction to obtain a precursor; (2) mixing the precursor, cysteine, 3-(trimethoxysilyl) methyl propyl methacrylate and a solvent, and performing two-step reaction to obtain a grafted precursor; (3) mixing the grafted precursor, N-isopropyl acrylamide, an initiator and a crosslinking agent with a solvent, and performing three-step reaction to obtain the lithium extraction adsorbent. The ordered vacancy type layered structure formed by inserting LiCl into Al(OH)3 is modified by grafting a sulfonic acid group and compounding a heat-sensitive polymer, and the prepared adsorbent can adjust the pore size according to the desorption temperature, so that the desorption rate of Li+ of the adsorbent is increased, and the lithium extraction efficiency is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of lithium extraction from salt lakes, and relates to a lithium extraction adsorbent and a preparation method and application thereof. BACKGROUND

[0002] In recent years, due to the wide use of lithium ion batteries in electronic products and electric vehicles, the global consumption of lithium has rapidly increased, and about 76% of the global lithium resources exist in brine. At present, the extraction methods of lithium include evaporation crystallization, membrane filtration, precipitation, extraction and adsorption. Among them, the adsorbent method is a method for selectively adsorbing lithium ions by using an adsorbent. After adsorbing lithium ions, the lithium ions can be eluted by acid, so as to separate the lithium ions from other ions. The adsorbent method has the advantages of easy regeneration, simple operation, high recovery rate and the like, and is one of the most promising lithium extraction methods.

[0003] At present, the adsorption technology for extracting lithium from salt lakes includes aluminum-based adsorbents, manganese-based adsorbents and titanium-based adsorbents. The preparation methods of the existing aluminum-based adsorbents mainly include precipitation method, hydrothermal method and the like. As a key material for extracting lithium from brine, the aluminum-based adsorbent has the advantages of low cost, high universality, stable performance and no need to consume acid in the elution process.

[0004] CN116832766A discloses a lithium adsorbent and a preparation method thereof. The lithium adsorbent has a porous structure and comprises an aluminum-based lithium adsorbent active material and a hydrophilic binder.

[0005] CN116829257A discloses an aluminum-based lithium adsorbent and a preparation method thereof. The preparation method comprises the following steps: mixing aluminum chloride and a sodium hydroxide solution, heating and reacting to obtain a precursor; mixing the obtained precursor with lithium chloride and adding MoS2, and then ball milling to obtain the aluminum-based lithium adsorbent.

[0006] The above scheme has low selective adsorption performance and low adsorption rate of Li + , which limits its practical application. SUMMARY

[0007] The application aims to provide a lithium extraction adsorbent and a preparation method and application thereof. The lithium extraction adsorbent is prepared by inserting LiCl into Al(OH)3 to form an ordered vacancy type layered structure, and then grafting modification by a sulfonic acid group and compounding with a heat-sensitive polymer. The lithium extraction adsorbent has stable structure and high adsorption rate. The pore size of the adsorbent can be adjusted according to the elution temperature, so as to increase the elution rate of Li+ of the adsorbent and further improve the lithium extraction efficiency.

[0008] To achieve the application purpose, the following technical scheme is adopted.

[0009] In a first aspect, the present application provides a preparation method of a lithium extraction adsorbent, the preparation method comprising the following steps:

[0010] (1) mixing an aluminum salt and lithium chloride with a solvent, adding a lye to perform a one-step reaction, and obtaining a LiAl-LDHs precursor;

[0011] (2) mixing the LiAl-LDHs precursor, cysteine, 3-(trimethoxysilyl)propyl methacrylate and a solvent to perform a two-step reaction, and obtaining a grafted LiAl-LDHs-SH precursor;

[0012] (3) mixing the grafted LiAl-LDHs-SH precursor, N-isopropyl acrylamide, an initiator and a crosslinking agent with a solvent to perform a three-step reaction, and obtaining the lithium extraction adsorbent.

[0013] The ordered vacancy type layered structure formed by inserting LiCl into Al(OH)3 has memory effect and steric hindrance effect, can realize selective adsorption of Li + in brine, the sulfonic acid group of cysteine is grafted in situ on the pores and surface of the porous LiAl-LDHs adsorbent by using 3-(trimethoxysilyl)propyl methacrylate (TPM), and the size screening adsorption of layered LiAl-LDHs and the pre-enrichment of the sulfonic acid group with high affinity for lithium are synergized, so that the lithium extraction adsorbent has increased affinity for Li + and improved adsorption rate. Then, the thermosensitive polymer is compounded with the adsorbent to form a stable solidified structure, the pore size of the adsorbent can be adjusted by the thermosensitive polymer changing with temperature, the pore size of the adsorbent is increased in the desorption process by increasing the temperature of the desorption solution, so as to increase the desorption rate of Li+ of the adsorbent, and finally the lithium extraction efficiency is significantly improved.

[0014] Preferably, the aluminum salt in step (1) comprises aluminum chloride and / or aluminum chloride hydrate.

[0015] Preferably, the molar ratio of the aluminum salt to lithium chloride is (1.5-2.5):1, for example, 1.5:1, 1.8:1, 2:1, 2.2:1 or 2.5:1, etc.

[0016] Preferably, the solvent comprises water.

[0017] Preferably, the pH of the one-step reaction in step (1) is 3-4, for example, 3, 3.2, 3.5, 3.8 or 4, etc.

[0018] Preferably, the temperature of the one-step reaction is 40-80℃, for example, 40℃, 50℃, 60℃, 70℃ or 80℃, etc.

[0019] Preferably, the time of the one-step reaction is 1-3 h, for example, 1 h, 1.5 h, 2 h, 2.5 h, or 3 h, etc.

[0020] Preferably, a washing, drying, and grinding process is performed after the one-step reaction.

[0021] Preferably, the solid-liquid ratio of the LiAl-LDHs precursor and the solvent in step (2) is 1:(5-10) g / mL, for example, 1:5 g / mL, 1:6 g / mL, 1:7 g / mL, 1:8 g / mL, or 1:10 g / mL, etc.

[0022] Preferably, the solvent comprises water.

[0023] Preferably, the mass ratio of the LiAl-LDHs precursor, cysteine, and 3-(trimethoxysilyl) methyl propyl methacrylate is 1:(0.2-0.3):(0.4-0.5), for example, 1:0.2:0.4, 1:0.25:0.4, 1:0.3:0.45, 1:0.3:0.4, or 1:0.3:0.5, etc.

[0024] Preferably, the temperature of the two-step reaction in step (2) is 50-90°C, for example, 50°C, 60°C, 70°C, 80°C, or 90°C, etc.

[0025] Preferably, the time of the two-step reaction is 5-10 h, for example, 5 h, 6 h, 8 h, 9 h, or 10 h, etc.

[0026] Preferably, a solid-liquid separation and drying process is performed after the two-step reaction.

[0027] Preferably, the initiator in step (3) comprises any one or a combination of at least two of azobisisobutyronitrile, dibenzoyl peroxide, or tert-butyl peroxide.

[0028] Preferably, the crosslinking agent comprises N,N-methylenebisacrylamide.

[0029] Preferably, the solvent comprises any one or a combination of at least two of tetrahydrofuran, toluene, benzene, chloroform, or dichloromethane.

[0030] Preferably, the mass ratio of the grafted LiAl-LDHs-SH precursor, N-isopropyl acrylamide, initiator, crosslinking agent, and solvent is 1:(1-5):(0.1-0.6):(0.05-0.2):(5-20), for example, 1:1:0.2:0.05:5, 1:2:0.3:0.1:10, 1:4:0.4:0.08:12, 1:3:0.5:0.15:10, or 1:5:0.6:0.2:20, etc.

[0031] The present application uses N-isopropyl acrylamide, an initiator and a crosslinking agent to form a heat-sensitive polymer, which expands in volume at a lower critical transition temperature (40℃) and shrinks in volume at a higher critical transition temperature (40℃) due to the stretching of the molecular chain of the heat-sensitive polymer, so that the heat-sensitive polymer, when combined with an aluminum-based adsorbent, can adjust the pore size of the adsorbent by utilizing the temperature-dependent properties of the heat-sensitive polymer, improve the adsorption efficiency while improving the selectivity of lithium ions by pre-enriching the small voids of the adsorbent and the sulfonic acid groups on the adsorbent during the adsorption of lithium ions, and increase the rate of desorption of Li+ from the adsorbent by increasing the temperature of the desorption solution during the desorption process, thereby significantly improving the lithium extraction efficiency.

[0032] Preferably, the temperature of the three-step reaction in step (3) is 60-70℃, for example: 60℃, 62℃, 65℃, 68℃ or 70℃, etc.

[0033] Preferably, the time of the three-step reaction is 12-24h, for example: 12h, 15h, 18h, 20h or 24h, etc.

[0034] Preferably, the three-step reaction in step (3) is followed by extrusion granulation and drying treatment of the obtained coagulation product.

[0035] In a second aspect, the present application provides a lithium extraction adsorbent prepared by the method of the first aspect.

[0036] In a third aspect, the present application provides the use of a lithium extraction adsorbent as described in the second aspect for lithium extraction from salt lakes.

[0037] Preferably, the adsorption temperature for lithium extraction from salt lakes is 20-30℃, for example: 20℃, 22℃, 25℃, 28℃ or 30℃, etc.

[0038] Preferably, the desorption temperature for lithium extraction from salt lakes is 50-70℃, for example: 50℃, 55℃, 60℃, 65℃ or 70℃, etc.

[0039] Compared with the prior art, the present application has the following beneficial effects:

[0040] (1) The present application inserts LiCl into Al(OH)3 to form an ordered vacancy-type layered structure, and then grafts and modifies it with a sulfonic acid group and composites it with a heat-sensitive polymer, thereby preparing a lithium extraction adsorbent with stable structure and high adsorption rate, which can adjust the pore size according to the desorption temperature, thereby increasing the rate of desorption of Li+ from the adsorbent and improving the lithium extraction efficiency.

[0041] (2) The lithium extraction adsorbent prepared by the method of the present application has high selectivity for lithium ions and can be used for lithium extraction.+ The adsorption capacity can reach 7.74 mg / g or more, Li + The elution capacity can reach 6.97 mg / g or more, and the Li + concentration in the elution solution can reach 2.65 g / L or more, while the Na + concentration can reach 0.14 g / L or less, the Mg 2+ concentration can reach 0.16 g / L or less, and the Ca 2+ concentration can reach 0.08 g / L or less. The lithium extraction adsorbent described in the application has a faster adsorption and elution rate of lithium ions and higher selectivity. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 is a schematic diagram of the adsorption and elution process in the lithium extraction method described in application example 1 of the application. DETAILED DESCRIPTION

[0043] The technical solutions of the application will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only to help understand the application and should not be regarded as specific limitations on the application.

[0044] The concentration of Glauber's salt used in the application examples and the comparative application examples is as follows:

[0045] Sodium ions: 23.0 g / L, magnesium ions: 18.3 g / L, lithium ions: 0.5 g / L, boron element: 3.75 g / L, chloride ions: 34 g / L, calcium ions: 7.7 g / L, and carbonate: 10.1 g / L.

[0046] Example 1

[0047] This embodiment provides a lithium extraction adsorbent, and the preparation method of the lithium extraction adsorbent is as follows:

[0048] (1) A certain amount of AlCl3·6H2O and LiCl is weighed according to the aluminum-lithium molar ratio of 2:1, dissolved in deionized water, and stirred uniformly. NaOH solution is added dropwise into the obtained mixed solution to control the pH to 3.5, and the reaction is carried out at a temperature of 60℃ for 2h. After the reaction is completed, solid-liquid separation is performed by suction filtration, and then the obtained sample is washed with deionized water for 3 times, and dried at 80℃ for 12h. The dried sample is ground to obtain a LiAl-LDHs precursor;

[0049] (2) The obtained LiAl-LDHs precursor was dispersed in deionized water at a solid-liquid ratio of 1 g: 7 mL, and then cysteine and 3-(trimethoxysilyl) methyl propyl methacrylate were added. After reaction at 70°C for 7 h, solid-liquid separation was performed, and the grafted sulfonic acid group LiAl-LDHs-SH precursor was obtained after drying. The mass ratio of the LiAl-LDHs precursor, cysteine, and 3-(trimethoxysilyl) methyl propyl methacrylate was 1:0.25:0.45;

[0050] (3) The grafted sulfonic acid group LiAl-LDHs-SH precursor was dispersed in tetrahydrofuran, and then N-isopropyl acrylamide, azobisisobutyronitrile, and N,N-methylene bisacrylamide were added. After removing air by nitrogen blowing, crosslinking polymerization was performed at a temperature of 65°C for 18 h. The mass ratio of the adsorbent, tetrahydrofuran, N-isopropyl acrylamide, azobisisobutyronitrile, and N,N-methylene bisacrylamide was 1:15:3:0.3:0.1. The obtained coagulation product was extruded and granulated, and then dried at a temperature of 50°C for 8 h to obtain the lithium extraction adsorbent.

[0051] Example 2

[0052] The present embodiment provides a lithium extraction adsorbent, and a preparation method thereof is as follows:

[0053] (1) A certain amount of AlCl3·6H2O and LiCl were weighed according to an aluminum-lithium molar ratio of 1.5:1, dissolved in deionized water, and uniformly stirred. NaOH solution was added dropwise into the obtained mixed solution to control the pH to 3, and then reaction was performed at a temperature of 80°C for 1 h. After reaction was completed, solid-liquid separation was performed by suction filtration, and then the sample was washed with deionized water for 3 times and dried at 80°C for 12 h. After drying, the sample was ground to obtain a LiAl-LDHs precursor;

[0054] (2) The obtained LiAl-LDHs precursor was dispersed in deionized water at a solid-liquid ratio of 1 g: 10 mL, and then cysteine and 3-(trimethoxysilyl) methyl propyl methacrylate were added. After reaction at 90°C for 5 h, solid-liquid separation was performed, and the grafted sulfonic acid group LiAl-LDHs-SH precursor was obtained after drying. The mass ratio of the LiAl-LDHs precursor, cysteine, and 3-(trimethoxysilyl) methyl propyl methacrylate was 1:0.2:0.5;

[0055] (3) The LiAl-LDHs-SH precursor grafted with sulfonic acid groups is dispersed in tetrahydrofuran, and then N-isopropyl acrylamide, azobisisobutyronitrile and N,N-methylene bisacrylamide are added, and after the air is removed by nitrogen blowing, crosslinking polymerization is carried out at a temperature of 60°C for 24h. The mass ratio of the adsorbent, tetrahydrofuran, N-isopropyl acrylamide, azobisisobutyronitrile and N,N-methylene bisacrylamide is 1:5:1:0.1:0.05. The obtained coagulation product is extruded into granules and dried, the drying temperature is 50°C, and the drying time is 8h, to obtain the lithium extraction adsorbent.

[0056] Example 3

[0057] The present embodiment provides a lithium extraction adsorbent, and a preparation method thereof is as follows:

[0058] (1) A certain amount of AlCl3·6H2O and LiCl is weighed according to the molar ratio of aluminum to lithium of 2.5:1, dissolved in deionized water and stirred uniformly, NaOH solution is added dropwise into the obtained mixed solution, the pH is controlled to be 4, and the reaction is carried out at a temperature of 40°C for 3h. After the reaction is completed, solid-liquid separation is carried out by suction filtration, and then washing with deionized water for 3 times, drying at 80°C for 12h, grinding the dried sample, to obtain a LiAl-LDHs precursor;

[0059] (2) The obtained LiAl-LDHs precursor is dispersed in deionized water at a solid-liquid ratio of 1g:5mL, and then cysteine and 3-(trimethoxysilyl) methyl propyl methacrylate are added, and after the reaction is carried out at 50°C for 10h, solid-liquid separation and drying are carried out, to obtain a LiAl-LDHs-SH precursor grafted with sulfonic acid groups. The mass ratio of the LiAl-LDHs precursor, cysteine and 3-(trimethoxysilyl) methyl propyl methacrylate is 1:0.3:0.4;

[0060] (3) The LiAl-LDHs-SH precursor grafted with sulfonic acid groups is dispersed in toluene, and then N-isopropyl acrylamide, azobisisobutyronitrile and N,N-methylene bisacrylamide are added, and after the air is removed by nitrogen blowing, crosslinking polymerization is carried out at a temperature of 70°C for 12h. The mass ratio of the adsorbent, toluene, N-isopropyl acrylamide, azobisisobutyronitrile and N,N-methylene bisacrylamide is 1:20:5:0.6:0.2. The obtained coagulation product is extruded into granules and dried, the drying temperature is 50°C, and the drying time is 8h, to obtain the lithium extraction adsorbent.

[0061] Example 4

[0062] The present embodiment is different from example 1 only in that the molar ratio of aluminum to lithium is 1:1, and other conditions and parameters are completely the same as those of example 1.

[0063] Example 5

[0064] The difference between this example and Example 1 is only that the molar ratio of aluminum to lithium is 3:1, and other conditions and parameters are exactly the same as those in Example 1.

[0065] Example 6

[0066] The difference between this example and Example 1 is only that the mass ratio of LiAl-LDHs precursor to cysteine is 1:0.1, and other conditions and parameters are exactly the same as those in Example 1.

[0067] Example 7

[0068] The difference between this example and Example 1 is only that the mass ratio of LiAl-LDHs precursor to cysteine is 1:0.5, and other conditions and parameters are exactly the same as those in Example 1.

[0069] Example 8

[0070] The difference between this example and Example 1 is only that the mass ratio of LiAl-LDHs-SH precursor to N-isopropyl acrylamide is 1:0.5, and other conditions and parameters are exactly the same as those in Example 1.

[0071] Example 9

[0072] The difference between this example and Example 1 is only that the mass ratio of LiAl-LDHs-SH precursor to N-isopropyl acrylamide is 1:8, and other conditions and parameters are exactly the same as those in Example 1.

[0073] Comparative Example 1

[0074] The difference between this comparative example and Example 1 is only that step (2) of grafting sulfonic acid groups is not performed, and other conditions and parameters are exactly the same as those in Example 1.

[0075] Comparative Example 2

[0076] The difference between this comparative example and Example 1 is only that step (3) of heat-sensitive polymer composite crosslinking is not performed, and other conditions and parameters are exactly the same as those in Example 1.

[0077] Application Example 1

[0078] The salt lake lithium extraction method provided in this application example comprises the following steps:

[0079] The lithium extraction adsorbent prepared in Example 1 is added to the brine, and the ion content in the brine is: under the conditions of a temperature of 25°C, a stirring speed of 300 r / min, and an adsorption time of 2 h, an adsorption experiment is performed, 500 mL of deionized water is taken after filtration, and under the conditions of a temperature of 55°C, a stirring speed of 300 r / min, and a desorption time of 2 h, a desorption experiment is performed.

[0080] The process schematic of the adsorption and desorption is shown in Figure 1 .

[0081] Application Example 2

[0082] The difference between this application example and application example 1 is that the lithium extraction adsorbent prepared in example 1 is replaced by the lithium extraction adsorbent prepared in example 2, and other conditions and parameters are completely the same as application example 1.

[0083] Application Example 3

[0084] The difference between this application example and application example 1 is that the lithium extraction adsorbent prepared in example 1 is replaced by the lithium extraction adsorbent prepared in example 3, and other conditions and parameters are completely the same as application example 1.

[0085] Application Example 4

[0086] The difference between this application example and application example 1 is that the lithium extraction adsorbent prepared in example 1 is replaced by the lithium extraction adsorbent prepared in example 4, and other conditions and parameters are completely the same as application example 1.

[0087] Application Example 5

[0088] The difference between this application example and application example 1 is that the lithium extraction adsorbent prepared in example 1 is replaced by the lithium extraction adsorbent prepared in example 5, and other conditions and parameters are completely the same as application example 1.

[0089] Application Example 6

[0090] The difference between this application example and application example 1 is that the lithium extraction adsorbent prepared in example 1 is replaced by the lithium extraction adsorbent prepared in example 6, and other conditions and parameters are completely the same as application example 1.

[0091] Application Example 7

[0092] The difference between this application example and application example 1 is that the lithium extraction adsorbent prepared in example 1 is replaced by the lithium extraction adsorbent prepared in example 7, and other conditions and parameters are completely the same as application example 1.

[0093] Application Example 8

[0094] The difference between this application example and application example 1 is that the lithium extraction adsorbent prepared in example 1 is replaced by the lithium extraction adsorbent prepared in example 8, and other conditions and parameters are completely the same as application example 1.

[0095] Application Example 9

[0096] The difference between this application example and application example 1 is that the lithium extraction adsorbent prepared in example 1 is replaced by the lithium extraction adsorbent prepared in example 9, and other conditions and parameters are completely the same as application example 1.

[0097] Comparative Application Example 1

[0098] The only difference between this comparative application example and application example 1 is that the lithium extraction adsorbent prepared in example 1 is replaced with the lithium extraction adsorbent prepared in comparative example 1, while the other conditions and parameters are exactly the same as in application example 1.

[0099] Comparative Application Example 2

[0100] The only difference between this comparative application example and application example 1 is that the lithium extraction adsorbent prepared in example 1 is replaced with the lithium extraction adsorbent prepared in comparative example 2, while the other conditions and parameters are exactly the same as in application example 1.

[0101] Comparative Application Example 3

[0102] The only difference between this comparative application example and application example 1 is that the adsorption and desorption experiments were both conducted at 25°C, while the other conditions and parameters were exactly the same as in application example 1.

[0103] Comparative Application Example 4

[0104] The only difference between this comparative application example and application example 1 is that the adsorption and desorption experiments were both conducted at 65°C, while the other conditions and parameters were exactly the same as in application example 1.

[0105] Performance testing:

[0106] The ion concentrations in the solutions before and after adsorption in both the application example and the control application example were determined using an atomic absorption spectrophotometer. The lithium-ion adsorption capacity was calculated using the following formula: Q t =(C0-C t )×V / m, where Q t It is the adsorption of Li + Adsorption capacity; C0 and C t Li at the initial stage of solution and after adsorption, respectively + Concentration, V is the volume of the solution; m is the weight of the adsorbent. The test results are shown in Table 1:

[0107] Table 1

[0108]

[0109]

[0110] As can be seen from Table 1, based on Application Examples 1-3, the lithium extraction adsorbent prepared by the method of the present invention is suitable for lithium extraction. + The adsorption capacity can reach over 7.74 mg / g, Li + The eluent capacity can reach over 6.97 mg / g, yielding Li in the eluent solution. + The concentration can reach above 2.65 g / L, while Na + Concentrations can reach below 0.14 g / L, Mg2+ The concentration can reach 0.16 g / L or below, Ca 2+ The concentration can reach 0.08 g / L or below, the lithium extraction adsorbent has a faster adsorption and desorption rate of lithium ions and a higher selectivity.

[0111] It can be seen from the comparison of Example 1 and Application Examples 4-5 that the molar ratio of aluminum salt and lithium chloride in the preparation process of the lithium extraction adsorbent of the application affects the performance. When the molar ratio of aluminum and lithium is controlled to be 1.5-2.5:1, the performance of the lithium extraction adsorbent prepared is better. If the amount of lithium chloride added is too large, the active sites in LiAl-LDHs will decrease, and the adsorption capacity of lithium ions in the solution will decrease. If the amount of lithium chloride added is too small, the synthesis rate of LiAl-LDHs will slow down, the purity of LiAl-LDHs will decrease, and thus the adsorption capacity will decrease.

[0112] It can be seen from the comparison of Example 1 and Application Examples 6-7 that the mass ratio of LiAl-LDHs precursor and cysteine in the preparation process of the lithium extraction adsorbent of the application affects the performance. When the mass ratio of LiAl-LDHs precursor and cysteine is controlled to be 1:0.2-0.3, the performance of the lithium extraction adsorbent prepared is better. If the amount of cysteine added is too large, the specific surface area of LiAl-LDHs will decrease, and thus the lithium adsorption capacity of the adsorbent will decrease. If the amount of cysteine added is too small, there will be too few sulfonic acid groups on the surface of LiAl-LDHs, and thus the selectivity of the adsorbent to lithium ions will decrease, and the content of impurity ions in the elution solution will increase.

[0113] It can be seen from the comparison of Example 1 and Application Examples 8-9 that the mass ratio of LiAl-LDHs-SH precursor and N-isopropyl acrylamide in the preparation process of the lithium extraction adsorbent of the application affects the performance. When the mass ratio of LiAl-LDHs-SH precursor and N-isopropyl acrylamide is controlled to be 1:1-5, the performance of the lithium extraction adsorbent prepared is better. If the amount of N-isopropyl acrylamide added is too large, the adsorption active sites of the adsorbent will decrease, and thus the adsorption capacity will decrease. If the amount of N-isopropyl acrylamide added is too small, the content of temperature-sensitive polymer in the adsorbent will be too low, and thus the pores of the adsorbent will be too small during the elution process, and the elution capacity of lithium will decrease.

[0114] It can be seen from the comparison of Application Example 1 and Comparative Application Example 1 that, by using 3-(trimethoxysilyl) methyl propyl methacrylate (TPM) to graft sulfonic acid groups in situ on the pores and surface of the porous LiAl-LDHs precursor, and by the size screening adsorption of the layered LiAl-LDHs and the pre-enrichment of the sulfonic acid groups with high affinity to lithium, the lithium extraction adsorbent has increased affinity to Li + and improved adsorption rate.

[0115] From the comparison of application example 1 and comparative application example 2, it can be seen that the present application can utilize the property of the heat-sensitive polymer changing with temperature to adjust the pore size of the adsorbent, and the smaller pore size of the adsorbent and the pre-enrichment effect of the sulfonic acid group on the adsorbent can improve the selectivity of lithium ions and the adsorption efficiency in the process of adsorbing lithium ions by the adsorbent. In the process of desorption, the pore size of the adsorbent can be increased by increasing the temperature of the eluent, thereby increasing the desorption rate of lithium ions by the adsorbent, and finally significantly improving the lithium extraction efficiency. + From the comparison of application example 1 and comparative application example 3-4, it can be seen that the temperature of adsorption and desorption will affect the lithium extraction and desorption effect. When the temperature is less than 40℃, the pore size of the adsorbent is small, and therefore the adsorption at room temperature can improve the selectivity of lithium ions by the adsorbent. When the temperature is greater than 40℃, the pore size of the adsorbent will increase, thereby reducing the selectivity of lithium ions. In the process of desorption of the adsorbent, the pore size of the adsorbent will increase under the action of the heat-sensitive polymer when the temperature is increased to greater than 40℃, thereby improving the desorption rate of the adsorbent and the desorption capacity of lithium.

[0116] From the comparison of application example 1 and comparative application example 3-4, it can be seen that the temperature of adsorption and desorption will affect the lithium extraction and desorption effect. When the temperature is less than 40℃, the pore size of the adsorbent is small, and therefore the adsorption at room temperature can improve the selectivity of lithium ions by the adsorbent. When the temperature is greater than 40℃, the pore size of the adsorbent will increase, thereby reducing the selectivity of lithium ions. In the process of desorption of the adsorbent, the pore size of the adsorbent will increase under the action of the heat-sensitive polymer when the temperature is increased to greater than 40℃, thereby improving the desorption rate of the adsorbent and the desorption capacity of lithium.

[0117] The applicant declares that the above description is only a specific embodiment of the present application, but the protection scope of the present application is not limited thereto. It should be understood by those skilled in the art that any changes or replacements within the technical scope disclosed by the present application can be easily thought of by those skilled in the art, and all fall within the protection scope and disclosure scope of the present application.

Claims

1. A method of preparing a lithium-uptake adsorbent, characterized by, The preparation method comprises the following steps: (1) mixing an aluminum salt and lithium chloride with a solvent, adding a lye to perform a one-step reaction to obtain a LiAl-LDHs precursor; (2) mixing the LiAl-LDHs precursor, cysteine, 3-(trimethoxysilyl)propyl methacrylate and a solvent to perform a two-step reaction to obtain a grafted LiAl-LDHs-SH precursor; (3) mixing the grafted LiAl-LDHs-SH precursor, N-isopropyl acrylamide, an initiator and a crosslinking agent with a solvent to perform a three-step reaction to obtain the lithium extraction adsorbent.

2. The production method according to claim 1, wherein The aluminum salt in step (1) comprises aluminum chloride and / or hydrated aluminum chloride.

3. The production method according to claim 1, wherein The molar ratio of the aluminum salt to lithium chloride is (1.5-2.5):

1.

4. The production method according to claim 1, wherein The solvent in step (1) comprises water.

5. The production method according to claim 1, wherein The pH of the one-step reaction in step (1) is 3-4.

6. The production method according to claim 1, wherein The temperature of the one-step reaction is 40-80°C.

7. The production method according to claim 1, wherein The time of the one-step reaction is 1-3h.

8. The production method according to claim 1, wherein Washing, drying and grinding treatment are performed after the one-step reaction.

9. The production method according to claim 1, wherein The solid-liquid ratio of the LiAl-LDHs precursor to the solvent in step (2) is 1:(5-10) g / mL.

10. The production method according to claim 1, wherein The solvent in step (2) comprises water.

11. The production method according to claim 1, wherein The mass ratio of the LiAl-LDHs precursor, cysteine and 3-(trimethoxysilyl)propyl methacrylate is 1:(0.2-0.3):(0.4-0.5).

12. The production method according to claim 1, wherein The temperature of the two-step reaction in step (2) is 50-90°C.

13. The production method according to claim 1, wherein The time of the two-step reaction is 5-10h.

14. The production method according to claim 1, wherein Solid-liquid separation and drying treatment are performed after the two-step reaction.

15. The production method according to claim 1, wherein The initiator in step (3) comprises any one or a combination of at least two of azobisisobutyronitrile, dibenzoyl peroxide or tert-butyl peroxide.

16. The production method according to claim 1, wherein The crosslinking agent comprises N,N-methylene bisacrylamide.

17. The production method according to claim 1, wherein The solvent in step (3) comprises any one or a combination of at least two of tetrahydrofuran, toluene, benzene, chloroform or dichloromethane.

18. The production method according to claim 1, wherein The mass ratio of the grafted LiAl-LDHs-SH precursor, N-isopropyl acrylamide, initiator, crosslinking agent and solvent is 1:(1-5):(0.1-0.6):(0.05-0.2):(5-20).

19. The production method according to claim 1, wherein The temperature of the three-step reaction in step (3) is 60-70°C.

20. The production method according to claim 1, wherein The time of the three-step reaction is 12-24h.

21. The production method according to claim 1, wherein Extrusion granulation and drying treatment are performed on the coagulation product obtained after the three-step reaction in step (3).

22. A lithium extraction adsorbent, characterized in that, The lithium extraction adsorbent is prepared by the method according to any one of claims 1-21.

23. The use of the lithium extraction adsorbent of claim 22, wherein the lithium extraction adsorbent is used in a lithium extraction process. The lithium extraction adsorbent is used for lithium extraction from a salt lake.

24. The use of the lithium extraction adsorbent of claim 23, wherein, The adsorption temperature for lithium extraction from the salt lake is 20-30°C.

25. The use of the lithium extraction adsorbent of claim 23, wherein the lithium extraction adsorbent is used in a lithium extraction process. The desorption temperature for lithium extraction from the salt lake is 50-70°C.

Images