High-entropy doped aluminum salt adsorbent as well as preparation method and application thereof

Abstract

The invention discloses a high-entropy doped aluminum salt adsorbent. The molecular formula of the high-entropy doped aluminum salt adsorbent is LiAl < x > M < y > (OH) < n > Cl < mH < 2 > O, wherein x is 1-5, y is 0-1, n is 6-15, and m is 0.5-10; m is a mixture of at least three of Ag < + >, Mg < 2 + >, Ca < 2 + >, Cu < 2 + >, Co < 2 + >, Zn < 2 + >, Fe < 3 + >, Mn < 2 + >, Ni < 2 + >, Ti < 4 + > and Zr < 4 + >. The preparation method comprises the following steps: S1, mixing a lithium salt, an aluminum salt and an M metal composite salt, and dissolving in deionized water to obtain a first mixed salt solution; s2, dropwise adding the alkaline solution into the first mixed salt solution, and adjusting the pH value to obtain a second mixed salt solution; s3, heating and aging the second mixed salt solution to obtain a precursor precipitate; sequentially carrying out centrifugal washing treatment and drying treatment on the precursor precipitate to obtain an adsorbent precursor; and S4, mixing the adsorbent precursor with deionized water, and carrying out oscillation activation treatment to obtain the high-entropy doped aluminum salt adsorbent. The prepared adsorbent can be used for extracting lithium from a lithium-containing solution, and has relatively good adsorption capacity, separation coefficient and circularity.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of lithium extraction from salt lakes and the field of chemical synthesis, and particularly relates to a high-entropy doped aluminum salt adsorbent as well as a preparation method and application thereof. BACKGROUND

[0002] Lithium ion batteries are favored due to their high energy density and long service life, and are widely used in various fields, which promotes the continuous rise of the demand for lithium resources. Therefore, efficient development of lithium resources is crucial. There are numerous salt lakes in the western plateau region of China, but most of the salt lake brines have the characteristics of high magnesium and low lithium (Mg / Li = 20-1000). Due to the similar physical and chemical properties of magnesium ions and lithium ions, separation is difficult, which makes lithium extraction from high magnesium-lithium ratio salt lake brine a recognized technical problem, seriously restricting the development and utilization of salt lake lithium resources. The main technologies for lithium extraction include adsorption, ion exchange, solvent extraction, membrane technology, and electrochemical technology. Among them, the adsorption method is one of the most promising methods for brine lithium extraction at present due to its high selectivity for lithium ions, simple operation, and low energy consumption.

[0003] The core material of the adsorption method is the adsorbent, which mainly includes organic adsorbents and inorganic adsorbents. Inorganic adsorbents based on manganese, titanium, and aluminum have excellent stability and cost-effectiveness, making inorganic adsorbents highly attractive in green and efficient lithium recovery work. Titanium-based adsorbents have good acid and alkali resistance, but the migration speed of lithium ions inside the adsorbent is slow, and the adsorption efficiency is low; manganese-based adsorbents have the advantages of large adsorption capacity and high adsorption efficiency, but they have poor acid and alkali resistance and high dissolution rate, which makes them unsuitable for carbonate-type salt lake lithium extraction. Aluminum-based lithium adsorbents, i.e., lithium / aluminum layered double hydroxides (Li / Al-LDH), stand out due to their excellent structural stability and become the adsorbent for industrial application. However, aluminum-based lithium adsorbents have the following shortcomings: (1) low adsorption capacity, less than half of that of manganese-based and titanium-based adsorbents; (2) poor resistance to sulfate, in lithium solutions containing sulfate, the binding force between sulfate and the adsorbent is strong after lithium ions are absorbed by the aluminum-based adsorbent, making regeneration difficult and leading to a significant decline in adsorption performance.

[0004] Therefore, there is an urgent need to develop a method for modifying aluminum-based lithium adsorbents to improve the structural and functional properties of aluminum salt adsorbents, increase their adsorption capacity, high adsorption efficiency, and prolong their cycle life. SUMMARY

[0005] To address the problems and shortcomings of existing technologies, this invention employs a high-entropy doping strategy to modify aluminum salt adsorbents, improving the structural defects of traditional aluminum salt adsorbents. Furthermore, a simple and efficient one-pot method is used to synthesize and dope aluminum salt adsorbents, resulting in the preparation of high-entropy-doped aluminum salt adsorbents. In addition, these high-entropy-doped aluminum salt adsorbents possess unique properties, such as multiple active sites, lattice distortion effects, and cocktail effects. These characteristics synergistically enhance the structural stability and adsorption-desorption capacity of the high-entropy-doped aluminum salt adsorbents, thereby enabling the high-entropy-doped aluminum salt adsorbents prepared by this invention to exhibit advantages such as high adsorption capacity, high adsorption efficiency, and long cycle life.

[0006] The first objective of this invention is to provide a high-entropy-doped aluminum salt adsorbent with the molecular formula LiAl. x M y (OH) n Cl·mH₂O; where: x is 1–5, y is 0–1, n is 6–15, m is 0.5–10; M is Ag + Mg 2+ Ca 2+ Cu 2+ Co 2+ Zn 2+ Fe 3+ Mn 2+ Ni 2+ Ti 4+ and Zr 4+ A mixture of at least three of them.

[0007] A second objective of this invention is to provide a method for preparing a high-entropy-doped aluminum-based lithium adsorbent as described above, the method comprising the following steps:

[0008] S1 mixes lithium salt, aluminum salt and M metal composite salt and dissolves them in deionized water, then mixes them by ultrasonication to obtain the first mixed salt solution;

[0009] S2 prepares an alkaline solution, adds the alkaline solution dropwise to the first mixed salt solution, adjusts the pH value to 5-8, and stirs evenly to obtain a second mixed salt solution;

[0010] S3 heats and ages the second mixed salt solution to obtain a precursor precipitate; the precursor precipitate is then subjected to centrifugal washing and drying to obtain an adsorbent precursor.

[0011] S4 The adsorbent precursor is mixed with deionized water, and a high-entropy doped aluminum salt adsorbent is obtained by oscillation activation treatment.

[0012] Specifically, the lithium salt in step S1 is any one or more of lithium chloride, lithium nitrate, lithium sulfate, lithium carbonate, and lithium hydroxide; the aluminum salt is any one or more of aluminum chloride, aluminum nitrate, aluminum sulfate, aluminum silicate, and aluminum sulfide.

[0013] Specifically, the M metal complex salt mentioned in step S1 is obtained by mixing chlorides or nitrates of at least three metals selected from Ag, Mg, Ca, Cu, Co, Zn, Mn, Ni, Fe, Ti and Zr.

[0014] Specifically, in step S1, the lithium salt and aluminum salt are mixed in a Li:Al molar ratio of 1:(0.5-3); the M metal composite salt and lithium salt are mixed in a M:Li molar ratio of (1-20):(80-99).

[0015] Specifically, in step S2, the dropping rate of the alkaline solution added to the first mixed salt solution is 0.5–10 ml / min, and the stirring rate is 100–500 r / min.

[0016] Specifically, the alkaline solution in step S2 is any one of sodium hydroxide, potassium hydroxide, sodium aluminate, urea, and ammonia water.

[0017] Specifically, in step S3, the heating time for heating and aging is 0.1 to 4 hours, the heating temperature is 25 to 95°C, and the aging time is 0.1 to 4 hours.

[0018] Specifically, the washing solution for the centrifugal washing process in step S3 is any one of deionized water, ethanol, and methanol; the drying process is freeze drying.

[0019] Specifically, in step S4, the solid-liquid ratio of the adsorbent precursor to deionized water is 40–200 g / L; the oscillation speed of the oscillation activation treatment is 10–1000 rpm, the oscillation time is 0.1–4 h, and the oscillation temperature is 25–35 °C.

[0020] The third objective of this invention is to provide an application of the high-entropy doped aluminum salt adsorbent in extracting lithium ions from a lithium-containing solution; the concentration of the aluminum salt lithium adsorbent in the lithium-containing solution is 0.01–10 g / L; the lithium-containing solution is at least one of salt lake brine, concentrated lithium-containing brine from salt fields, well water, and seawater.

[0021] Compared with the prior art, the present invention has the following beneficial technical effects:

[0022] (1) This invention proposes a novel high-entropy doped aluminum salt adsorbent, which introduces a high-energy-density metal cation M (such as Fe) into an aluminum-based framework. 3+ Co 2+Strengthening the structural stability of the laminates enhances the material's cycling performance; this is achieved by introducing elements with low charge density (such as Zn). 2+ Cu 2+ Promote the generation of lattice oxygen vacancies, thereby enhancing the lithium extraction performance of the material; introduce elements with large ionic radii (such as Zr) 4+ Ti 4+ The interlayer spacing of the material is increased by changing the interplanar spacing; the synergistic introduction of three or more dopants brings lattice distortion effect and cocktail effect to the adsorbent, regulates the adsorption of reaction intermediates, and thus improves the adsorption capacity of aluminum salt adsorbent.

[0023] (2) The present invention successfully synthesized a high-entropy doped aluminum salt adsorbent using a simple and efficient doping strategy. The doping modification process is simple. Under mild conditions, doping and synthesis can be carried out simultaneously through co-precipitation and intercalation. The energy consumption is low, the synthesis cycle is short, and there is no need for complex reaction devices and complex reaction condition control. The adsorbent prepared by the present invention can extract lithium from lithium-containing solutions with low lithium concentration and high impurity ion concentration (such as lithium-containing solutions such as salt lake brine, well water, and seawater), and has good adsorption capacity, separation coefficient and cycle performance. Attached Figure Description

[0024] Figure 1 The XRD patterns of the high-entropy doped 3% aluminum salt adsorbent prepared in Example 1 of the present invention and the aluminum salt adsorbent prepared in Comparative Example 1 are shown in comparison.

[0025] Figure 2 (a) is a SEM image of the aluminum salt adsorbent prepared in Comparative Example 1 of the present invention;

[0026] Figure 2 (b) SEM image of the high-entropy doped 3% aluminum salt adsorbent prepared in Example 1 of the present invention;

[0027] Figure 3 The XRD patterns of the 5% single-doped aluminum-based lithium adsorbents prepared in Comparative Examples 2-6 of this invention are shown.

[0028] Figure 4 The saturated adsorption capacity of the 5% single-doped aluminum-based lithium adsorbent precursors prepared in Comparative Examples 2-6 of this invention;

[0029] Figure 5 This is a comparison chart of the cyclic adsorption capacity of the high-entropy doped 3% aluminum salt adsorbent prepared in Example 1 of the present invention and the aluminum salt adsorbent prepared in Comparative Example 1.

[0030] Figure 6 A comparison chart of the cyclic adsorption capacity of the high-entropy doped 15% aluminum salt adsorbent prepared in Example 2 of the present invention and the aluminum salt adsorbent prepared in Comparative Example 1.

[0031] Figure 7 This is a comparison chart of the cyclic adsorption capacity of the high-entropy doped 5% aluminum salt adsorbent prepared in Example 3 of the present invention and the aluminum salt adsorbent prepared in Comparative Example 1.

[0032] Figure 8 A comparison chart of the cyclic adsorption capacity of the high-entropy doped 25% aluminum-based lithium adsorbent prepared in Example 4 of the present invention and the aluminum salt adsorbent prepared in Comparative Example 1. Detailed Implementation

[0033] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing specific embodiments only and is not intended to limit the present invention.

[0034] Example 1

[0035] The M metal complex salt is a mixture of zinc chloride (ZnCl2), ferric chloride (FeCl3), and magnesium chloride (MgCl2);

[0036] S1 Weigh 25.8g of aluminum chloride (AlCl3), 6.8g of lithium chloride (LiCl), 0.273g of ZnCl2, 0.325g of FeCl3, and 0.190g of MgCl2 and dissolve them in 100ml of deionized water. The molar ratio of Li to Al is 1:1.21; the molar ratio of Li to (Al+Zn+Fe+Mg) is 1:1.25; the molar ratio of Zn to Fe to Mg to Li is 1:1:1:80; and the molar ratio of Al to Zn to Fe to Mg is 97:1:1:1. After sonication for 15 minutes, the mixture is homogeneous to obtain the first mixed salt solution a.

[0037] S2 prepares an alkaline solution of NaOH with a concentration of 4 mol / L and adds it dropwise at a rate of 3 ml / min to the reaction vessel containing the first mixed salt solution a. The pH value at the endpoint of the addition is controlled at 7, and the stirring speed is 200 rpm. After stirring evenly, the second mixed salt solution a is obtained.

[0038] S3 heated the second mixed salt solution a at 75°C for 1 hour, then allowed it to stand for 0.5 hours to obtain precursor precipitate a; after centrifugation, it was washed with deionized water and freeze-dried for 12 hours to obtain adsorbent precursor a.

[0039] S4 mixed adsorbent precursor a with deionized water at a solid-liquid ratio of 100 g / mL and activated by shaking at 200 rpm for 4 h to obtain high-entropy doped aluminum salt adsorbent a with the molecular formula LiAl. 1.94 Zn 0.02 Fe 0.02 Mg 0.02 (OH) n Cl·mH2O, denoted as 3%GS-LDH.

[0040] Example 2

[0041] The M metal complex salt is a mixture of ZnCl2, FeCl3, and MgCl2;

[0042] S1 Weigh 22.6g of AlCl3, 6.8g of LiCl, 1.364g of ZnCl2, 1.624g of FeCl3, and 0.962g of MgCl2 and dissolve them in 100ml of deionized water. The molar ratio of Li to Al is 1:1.06; the molar ratio of Li to (Al+Zn+Fe+Mg) is 1:1.25; the molar ratio of Zn:Fe:Mg:Li is 5:5:5:80; and the molar ratio of Al:Zn:Fe:Mg is 85:5:5:5. After sonication for 15min, the mixture is homogeneous to obtain the first mixed salt solution b.

[0043] S2 prepares an alkaline solution of NaOH with a concentration of 4 mol / L and adds it dropwise at a rate of 0.5 ml / min to the reaction vessel containing the first mixed salt solution b. The pH value at the endpoint of the addition is controlled at 5.8, and the stirring speed is 100 rpm. After stirring evenly, the second mixed salt solution b is obtained.

[0044] S3 heated the second mixed salt solution b at 50°C for 0.1 h, and then allowed it to stand for 0.1 h to obtain the precursor precipitate b; after centrifugation, it was washed with deionized water and freeze-dried for 12 h to obtain the adsorbent precursor b.

[0045] S4 mixed adsorbent precursor b with deionized water at a solid-liquid ratio of 40 g / mL and activated by shaking at 1000 rpm for 0.1 h to obtain high-entropy doped aluminum salt adsorbent b with the molecular formula LiAl. 1.7 Zn 0.1 Fe 0.1 Mg 0.1 (OH) n Cl·mH2O, denoted as 15% GS-LDH.

[0046] Example 3

[0047] The M metal complex salt is a mixture of ZnCl2, FeCl3, MgCl2, cobalt chloride CoCl2, and copper chloride CuCl2;

[0048] S1: Weigh 25.3g of AlCl3, 6.8g of LiCl, 0.273g of ZnCl2, 0.325g of FeCl3, 0.190g of MgCl2, 0.274g of CuCl2, and 0.260g of CoCl2 and dissolve them in 100ml of deionized water; wherein, the molar ratio of Li:Al is 1:1.19; the molar ratio of Li:(Al+Zn+Fe+Mg+Co+Cu) is 1:1.25; the molar ratio of Zn:Fe:Mg:Co:Cu:Li is 1:1:1:1:1:80; and the molar ratio of Al:Zn:Fe:Mg:Co:Cu is 95:1:1:1:1:1:1. After sonication for 15min, mix thoroughly to obtain the first mixed salt solution c.

[0049] S2 prepares an alkaline solution of NaOH with a concentration of 4 mol / L and adds it dropwise at a rate of 10 ml / min to the reaction vessel containing the first mixed salt solution c. The pH value at the endpoint of the addition is controlled at 7.5, and the stirring speed is 500 rpm. After stirring evenly, the second mixed salt solution c is obtained.

[0050] S3 heated the second mixed salt solution c at 95℃ for 0.5h, and then allowed it to stand for aging for 0.5h to obtain the precursor precipitate c; after centrifugation, it was washed with deionized water and freeze-dried for 12h to obtain the adsorbent precursor c.

[0051] S4 mixed adsorbent precursor c with deionized water at a solid-liquid ratio of 200 g / mL and activated by shaking at 150 rpm for 2 h to obtain high-entropy doped aluminum salt adsorbent c with the molecular formula LiAl. 1.90 Zn 0.02 Fe 0.02 Mg 0.02 Co 0.02 Cu 0.02 (OH) n Cl·mH2O, denoted as 5%GS-LDH.

[0052] Example 4

[0053] The M metal complex salt is a mixture of ZnCl2, FeCl3, MgCl2, CoCl2 and CuCl2;

[0054] S1: Weigh 19.95g of AlCl3, 6.8g of LiCl, 1.364g of ZnCl2, 1.624g of FeCl3, 0.962g of MgCl2, 1.372g of CuCl2, and 1.302g of CoCl2 and dissolve them in 100ml of deionized water. The molar ratio of Li to Al is 1:0.94; the molar ratio of Li to (Al+Zn+Fe+Mg+Co+Cu) is 1:1.25; the molar ratio of Zn:Fe:Mg:Co:Cu:Li is 5:5:5:5:5:5:80; and the molar ratio of Al:Zn:Fe:Mg:Co:Cu is 75:5:5:5:5:5:5. After sonication for 15min, the mixture is thoroughly mixed to obtain the first mixed salt solution d.

[0055] S2 prepares an alkaline solution of NaOH with a concentration of 4 mol / L and adds it dropwise at a rate of 1 ml / min to the reaction vessel containing the first mixed salt solution d. The pH value at the endpoint of the addition is controlled at 8, and the stirring speed is 100 rpm. After stirring evenly, the second mixed salt solution d is obtained.

[0056] S3 heated the second mixed salt solution d at 25°C for 4 hours, and then allowed it to stand for 4 hours to age, to obtain the precursor precipitate d; after centrifugation, it was washed with deionized water and freeze-dried for 12 hours to obtain the adsorbent precursor d.

[0057] S4 mixed adsorbent precursor d with deionized water at a solid-liquid ratio of 150 g / mL and activated by shaking at 600 rpm for 4 h to obtain high-entropy doped aluminum salt adsorbent d with the molecular formula LiAl. 1.5 Zn 0.01 Fe 0.1 Mg 0.1 Co 0.1 Cu 0.1 (OH) n Cl·mH2O, denoted as 25% GS-LDH.

[0058] Example 5

[0059] The M metal complex salt is a mixture of silver nitrate AgNO3, calcium nitrate Ca(NO3)2, manganese nitrate Mn(NO3)2, cobalt nitrate Co(NO3)2, nickel nitrate Ni(NO3)2 and zirconium chloride ZrCl4;

[0060] S1 Weigh out 33.87g of aluminum nitrate (Al(NO3)3), 10.0g of lithium carbonate (Li2CO3), 0.287g of AgNO3, 0.278g of Ca(NO3)2, 0.303g of Mn(NO3)2, 0.309g of Co(NO3)2, 0.309g of Ni(NO3)2, and 0.394g of ZrCl4, and dissolve them in 100ml of deionized water. The ratio of Li to Al is... The molar ratio is 1:1.18; the molar ratio of Li:(Al+Ag+Ca+Mn+Co+Ni+Zr) is 1:1.25, the molar ratio of Ag:Ca:Mn:Co:Ni:Zr:Li is 1:1:1:1:1:1:80; the molar ratio of Al:Ag:Ca:Mn:Co:Ni:Zr is 94:1:1:1:1:1:1:1; after sonication for 15 min, the mixture is homogeneous to obtain the first mixed salt solution e.

[0061] S2 prepares an alkaline solution of NaOH with a concentration of 4 mol / L and adds it dropwise at a rate of 1 ml / min to the reaction vessel containing the first mixed salt solution e. The pH value at the endpoint of the addition is controlled at 8, and the stirring speed is 100 rpm. After stirring evenly, the second mixed salt solution e is obtained.

[0062] S3 heated the second mixed salt solution d at 25°C for 4 hours, and then allowed it to stand for 4 hours to age, to obtain the precursor precipitate e; after centrifugation, it was washed with deionized water and freeze-dried for 12 hours to obtain the adsorbent precursor e.

[0063] S4 mixed adsorbent precursor e with deionized water at a solid-liquid ratio of 150 g / mL and activated by shaking at 600 rpm for 4 h to obtain high-entropy doped aluminum salt adsorbent e with the molecular formula LiAl. 1.88 Ag 0.02 Ca 0.02 Mn 0.02 Co 0.02 Ni 0.02 Zr 0.02 (OH) n Cl·mH2O, denoted as 6%HS-LDH.

[0064] Example 6

[0065] The M metal complex salt is a mixture of calcium chloride (CaCl2), copper nitrate (Cu(NO3)2), manganese nitrate (Mn(NO3)2), nickel nitrate (Ni(NO3)2), and titanium chloride (TiCl4).

[0066] S1 Weigh 96.82g of aluminum sulfate Al2(SO4)3, 10.0g of lithium hydroxide LiOH·H2O, 0.331g of CaCl2, 0.559g of Cu(NO3)2, 0.533g of Mn(NO3)2, 0.544g of Ni(NO3)2, and 0.565g of TiCl4 and dissolve them in 100ml of deionized water. The molar ratio of Li:Al is 1:1.19; the molar ratio of Li:(Al+Ca+Cu+Mn+Ni+Ti) is 1:1.25; the molar ratio of Ca:Cu:Mn:Ni:Ti:Li is 1:1:1:1:1:80; and the molar ratio of Al:Ca:Cu:Mn:Ni:Ti is 95:1:1:1:1:1:1. After sonication for 15min, the mixture is homogeneous to obtain the first mixed salt solution f.

[0067] S2 prepares an alkaline solution of NaOH with a concentration of 4 mol / L and adds it dropwise at a rate of 2 ml / min to the reaction vessel containing the first mixed salt solution d. The pH value at the endpoint of the addition is controlled at 8, and the stirring speed is 400 rpm. After stirring evenly, the second mixed salt solution f is obtained.

[0068] S3 heated the second mixed salt solution e at 70℃ for 2 hours, and then allowed it to stand for 2 hours to age, to obtain the precursor precipitate f; after centrifugation, it was washed with deionized water and freeze-dried for 12 hours to obtain the adsorbent precursor f.

[0069] S4 mixed the adsorbent precursor f with deionized water at a solid-liquid ratio of 80 g / mL and activated it by shaking at 600 rpm for 4 h to obtain the high-entropy doped aluminum salt adsorbent f with the molecular formula LiAl. 1.90 Ca 0.02 Cu 0.02 Mn 0.02 Ni 0.02 Ti 0.02 (OH) n Cl·mH2O, denoted as 5% IS-LDH.

[0070] Example 7

[0071] The M metal complex salt is a mixture of CoCl2, calcium chloride CaCl2, copper nitrate Cu(NO3)2, and titanium chloride TiCl4;

[0072] S1 Weigh 16.39g of aluminum sulfide Al2S3, 10.0g of lithium sulfate Li2SO4, 0.148g of CoCl2, 0.126g of CaCl2, 0.213g of Cu(NO3)2, and 0.216g of TiCl4 and dissolve them in 100ml of deionized water. The molar ratio of Li:Al is 1:1.20; the molar ratio of Li:(Al+Co+Ca+Cu+Ti) is 1:1.25; the molar ratio of Co:Ca:Cu:Ti:Li is 1:1:1:1:80; and the molar ratio of Al:Co:Ca:Cu:Ti is 96:1:1:1:1. After sonication for 15min, the mixture is homogeneous to obtain the first mixed salt solution h.

[0073] S2 prepares an alkaline solution of NaOH with a concentration of 4 mol / L and adds it dropwise at a rate of 3 ml / min to the reaction vessel containing the first mixed salt solution d. The pH value at the endpoint of the addition is controlled at 7, and the stirring speed is 400 rpm. After stirring evenly, the second mixed salt solution h is obtained.

[0074] S3 heated the second mixed salt solution e at 75℃ for 1 hour, then allowed it to stand for 0.5 hours to obtain the precursor precipitate h; after centrifugation, it was washed with deionized water and freeze-dried for 12 hours to obtain the adsorbent precursor h.

[0075] S4 mixed the adsorbent precursor h with deionized water at a solid-liquid ratio of 100 g / mL and activated it by shaking at 200 rpm for 4 h to obtain the high-entropy doped aluminum salt adsorbent h with the molecular formula LiAl. 1.90 Co 0.025 Ca 0.02 Cu 0.02 Ti 0.02 (OH) n Cl·mH2O, denoted as 4%JS-LDH.

[0076] Example 8

[0077] The M metal complex salt is a mixture of calcium chloride CaCl2, copper nitrate Cu(NO3)2, and titanium chloride TiCl4;

[0078] S1 Weigh 28.49g of aluminum silicate Al2SiO5, 10.0g of lithium nitrate LiNO3, 0.203g of CaCl2, 0.340g of Cu(NO3)2, and 0.344g of TiCl4 and dissolve them in 100ml of deionized water. The molar ratio of Li:Al is 1:1.21; the molar ratio of Li:(Al+Ca+Cu+Ti) is 1:1.25; the molar ratio of Ca:Cu:Ti:Li is 1:1:1:80; and the molar ratio of Al:Ca:Cu:Ti is 97:1:1:1. After sonication for 15min, the mixture is homogeneous to obtain the first mixed salt solution j.

[0079] S2 prepares an alkaline solution of NaOH with a concentration of 4 mol / L and adds it dropwise at a rate of 3 ml / min to the reaction vessel containing the first mixed salt solution j. The pH value at the endpoint of the addition is controlled at 8, and the stirring speed is 200 rpm. After stirring evenly, the second mixed salt solution j is obtained.

[0080] S3 heated the second mixed salt solution e at 75°C for 1 hour, then allowed it to stand for 0.5 hours to obtain the precursor precipitate j; after centrifugation, it was washed with deionized water and freeze-dried for 12 hours to obtain the adsorbent precursor j.

[0081] S4 mixed adsorbent precursor j with deionized water at a solid-liquid ratio of 100 g / mL and activated by shaking at 200 rpm for 4 h to obtain high-entropy doped aluminum salt adsorbent j with the molecular formula LiAl. 1.94 Ca 0.02 Cu 0.02 Ti 0.02 (OH) n Cl·mH2O is denoted as 3% KS-LDH.

[0082] Comparative Example 1

[0083] It contains no other metallic elements besides Al and Li;

[0084] S1 Weigh 26.6g AlCl3 and 6.8g LiCl and dissolve them in 100ml deionized water. The Li:Al molar ratio is 1:1.25. After sonication for 15min, the mixture is homogeneous to obtain lithium-aluminum mixed solution A.

[0085] S2 prepares an alkaline solution of NaOH with a concentration of 4 mol / L and adds it dropwise at a rate of 3 ml / min to the reaction vessel containing the lithium-aluminum mixed solution A. The pH value at the endpoint of the addition is controlled at 7, and the stirring speed is 200 rpm. The mixture is stirred evenly to obtain the mixed salt solution A.

[0086] S3 heated the mixed salt solution A at 75℃ for 1 hour, then allowed it to stand for 0.5 hours to obtain the precursor precipitate A; after centrifugation, it was washed with deionized water and freeze-dried for 12 hours to obtain the adsorbent precursor A.

[0087] S4 mixed adsorbent precursor A with deionized water at a solid-liquid ratio of 100 g / mL and activated it by shaking at 200 rpm for 4 h to obtain aluminum salt adsorbent A, denoted as LDH.

[0088] Comparative Example 2

[0089] M is only Zn, to prepare a single-doped aluminum salt adsorbent;

[0090] S1: Weigh 25.3g AlCl3, 6.8g LiCl, and 1.36g ZnCl2 and dissolve them in 100ml deionized water. The molar ratio of Li to Al is 1:1.19; the molar ratio of Li to (Al+Zn) is 1:1.25; the molar ratio of Zn to Li is 5:80; and the molar ratio of Al to Zn is 95:5. After sonication for 15 minutes, the mixture is homogeneous to obtain lithium-aluminum mixed solution B.

[0091] S2 prepares an alkaline solution of NaOH with a concentration of 4 mol / L and adds it dropwise at a rate of 3 ml / min to the reaction vessel containing the lithium-aluminum mixed solution B. The pH value at the endpoint of the addition is controlled at 7, and the stirring speed is 200 rpm. The mixture is stirred evenly to obtain the mixed salt solution B.

[0092] S3 heated the mixed salt solution B at 75℃ for 1 hour, then allowed it to stand for 0.5 hours to obtain the precursor precipitate B; after centrifugation, it was washed with deionized water and freeze-dried for 12 hours to obtain the adsorbent precursor B.

[0093] S4 mixed adsorbent precursor B with deionized water at a solid-liquid ratio of 100 g / mL and activated it by shaking at 200 rpm for 4 h to obtain aluminum salt adsorbent B, denoted as 5% Zn-LDH.

[0094] Comparative Example 3

[0095] M is only Fe, to prepare a single-doped aluminum salt adsorbent;

[0096] S1: Weigh 25.3g AlCl3, 6.8g LiCl, and 1.62g FeCl3 and dissolve them in 100ml deionized water. The molar ratio of Li to Al is 1:1.19; the molar ratio of Li to (Al+Fe) is 1:1.25; the molar ratio of Fe to Li is 5:80; and the molar ratio of Al to Fe is 95:5. After sonication for 15min, the mixture is homogeneous to obtain lithium-aluminum mixed solution C.

[0097] S2 prepares an alkaline solution of NaOH with a concentration of 4 mol / L and adds it dropwise at a rate of 3 ml / min to the reaction vessel containing the lithium-aluminum mixed solution C. The pH value at the endpoint of the addition is controlled at 7, and the stirring speed is 200 rpm. The mixture is stirred evenly to obtain the mixed salt solution C.

[0098] S3 heated the mixed salt solution C at 75℃ for 1 hour, then allowed it to stand for 0.5 hours to obtain the precursor precipitate C; after centrifugation, it was washed with deionized water and freeze-dried for 12 hours to obtain the adsorbent precursor C.

[0099] S4 mixed the adsorbent precursor C with deionized water at a solid-liquid ratio of 100 g / mL and activated it by shaking at 200 rpm for 4 h to obtain aluminum salt adsorbent A, denoted as 5% Fe-LDH.

[0100] Comparative Example 4

[0101] M is only Mg, to prepare a single-doped aluminum salt adsorbent;

[0102] S1: Dissolve 25.3g AlCl3, 6.8g LiCl, and 0.962g MgCl2 in 100ml deionized water. The molar ratio of Li to Al is 1:1.19; the molar ratio of Li to (Al+Mg) is 1:1.25; the molar ratio of Mg to Li is 5:80; and the molar ratio of Al to Mg is 95:5. After sonication for 15min, the mixture is homogeneous to obtain lithium-aluminum mixed solution D.

[0103] S2 prepares an alkaline solution of NaOH with a concentration of 4 mol / L and adds it dropwise at a rate of 3 ml / min to the reaction vessel containing the lithium-aluminum mixed solution D. The pH value at the endpoint of the addition is controlled at 7, and the stirring speed is 200 rpm. The mixture is stirred evenly to obtain the mixed salt solution D.

[0104] S3 heated the mixed salt solution D at 75℃ for 1 hour, then allowed it to stand for 0.5 hours to obtain the precursor precipitate D; after centrifugation, it was washed with deionized water and freeze-dried for 12 hours to obtain the adsorbent precursor D.

[0105] S4 mixed the adsorbent precursor D with deionized water at a solid-liquid ratio of 100 g / mL and activated it by shaking at 200 rpm for 4 h to obtain aluminum salt adsorbent D, denoted as 5% Mg-LDH.

[0106] Comparative Example 5

[0107] M is only Cu, to prepare a single-doped aluminum salt adsorbent;

[0108] S1: Dissolve 25.3g AlCl3, 6.8g LiCl, and 1.372g CuCl2 in 100ml deionized water. The molar ratio of Li to Al is 1:1.19; the molar ratio of Li to (Al+Cu) is 1:1.25; the molar ratio of Cu to Li is 5:80; and the molar ratio of Al to Cu is 95:5. After sonication for 15min, the mixture is homogeneous to obtain a lithium-aluminum mixed solution E.

[0109] S2 prepares an alkaline solution of NaOH with a concentration of 4 mol / L and adds it dropwise at a rate of 3 ml / min to the reaction vessel containing the lithium-aluminum mixed solution E. The pH value at the endpoint of the addition is controlled at 7, and the stirring speed is 200 rpm. The mixture is stirred evenly to obtain the mixed salt solution E.

[0110] S3 heated the mixed salt solution E at 75℃ for 1 hour, then allowed it to stand for 0.5 hours to obtain the precursor precipitate E; after centrifugation, it was washed with deionized water and freeze-dried for 12 hours to obtain the adsorbent precursor E.

[0111] S4 mixed the adsorbent precursor E with deionized water at a solid-liquid ratio of 100 g / mL and activated it by shaking at 200 rpm for 4 h to obtain aluminum salt adsorbent E, denoted as 5% Cu-LDH.

[0112] Comparative Example 6

[0113] M is only Co, to prepare a single-doped aluminum salt adsorbent;

[0114] S1: Dissolve 25.3g AlCl3, 6.8g LiCl, and 1.302g CoCl2 in 100ml deionized water. The molar ratio of Li to Al is 1:1.19; the molar ratio of Li to (Al+Co) is 1:1.25; the molar ratio of Co to Li is 5:80; and the molar ratio of Al to Co is 95:5. After sonication for 15min, the mixture is homogeneous to obtain a lithium-aluminum mixed solution F.

[0115] S2 prepares an alkaline solution of NaOH with a concentration of 4 mol / L and adds it dropwise at a rate of 3 ml / min to the reaction vessel containing the lithium-aluminum mixed solution F. The pH value at the endpoint of the addition is controlled at 7, and the stirring speed is 200 rpm. The mixture is stirred evenly to obtain the mixed salt solution F.

[0116] S3 heated the mixed salt solution F at 75℃ for 1 hour, then allowed it to stand for 0.5 hours to obtain the precursor precipitate F; after centrifugation, it was washed with deionized water and freeze-dried for 12 hours to obtain the adsorbent precursor F.

[0117] S4 mixed the adsorbent precursor F with deionized water at a solid-liquid ratio of 100 g / mL and activated it by shaking at 200 rpm for 4 h to obtain aluminum salt adsorbent F, denoted as 5% Co-LDH.

[0118] Performance testing

[0119] Figure 1 The XRD patterns of the high-entropy doped 3% aluminum salt adsorbent prepared in Example 1 and the aluminum salt adsorbent prepared in Comparative Example 1 are shown in the comparison. Figure 1 It can be seen that the doping of multiple elements did not significantly affect the structure of the aluminum salt adsorbent. The XRD diffraction peaks were basically consistent and there were no impurity peaks, forming a stable single solid solution phase. Figure 2 (a) is a SEM image of the aluminum salt adsorbent prepared in Comparative Example 1 of the present invention; Figure 2 (b) SEM image of the 3% high-entropy aluminum salt adsorbent prepared in Example 1 of this invention; from Figure 2 It can be seen that the interlayer spacing of the aluminum salt adsorbent increases before and after high entropy doping, and multiple elements are well coupled together and incorporated into the structure of the aluminum salt adsorbent.

[0120] Figure 3 The XRD patterns of the 5% single-doped aluminum-based lithium adsorbents prepared in Comparative Examples 2-6 of this invention are shown. Figure 4 Table 1 shows the saturated adsorption capacity of the 5% single-doped aluminum-based lithium adsorbent precursors prepared in Comparative Examples 2-6 of this invention; Table 1 shows the composition of the 5% single-doped aluminum-based lithium adsorbent precursors prepared in Comparative Examples 2-6 of this invention.

[0121] Table 1

[0122] Sample Name M n+ (mg / g) M n+ (mol / g)]]> Comparative Example 2 5% Cu-LDH 31866.32551 0.501468629 Comparative Example 3 5% Fe-LDH 26700.21327 0.478112871 Comparative Example 4 5% Co-LDH 31501.28495 0.534527089 Comparative Example 5 5% Zn-LDH 31077.65009 0.475266097 Comparative Example 6 5% Mg-LDH 8459.837272 0.348069832

[0123] As shown in Table 1, each individual dopant element successfully incorporated into the interior of the aluminum salt adsorbent. Figure 3 and Figure 4 It can be seen that the adsorption capacity of a single doped element is improved compared to that of an undoped adsorbent.

[0124] Application examples

[0125] The aluminum salt adsorbents prepared in Examples 1-8 and Comparative Documents 1-6 were added to concentrated lithium-containing brine in salt fields, respectively. The mixtures were placed in a constant-temperature air bath shaker and oscillated at 200 rpm, with the temperature maintained at 25°C. After 4 hours of reaction, the mixtures were removed, and ICP measurements were performed to determine the Li content in the concentrated lithium-containing brine before and after adsorption. + The change in the adsorption capacity Q of the aluminum salt adsorbents prepared in Examples 1-8 and Comparative Documents 1-6 can be obtained from the change in the adsorption capacity. e .

[0126] Figure 5This is a comparison chart of the cyclic adsorption capacity of the high-entropy doped 3% aluminum salt adsorbent prepared in Example 1 and the aluminum salt adsorbent prepared in Comparative Example 1; (The chart is composed of...) Figure 5 It can be seen that, compared with the undoped aluminum salt adsorbent, the adsorption capacity of the high-entropy doped aluminum salt adsorbent in Example 1 was increased by 6.67%. Figure 6 This is a comparison chart of the cyclic adsorption capacity of the high-entropy doped 15% aluminum salt adsorbent prepared in Example 2 of the present invention and the aluminum salt adsorbent prepared in Comparative Example 1; Figure 6 It can be seen that, compared with the undoped aluminum salt adsorbent, the adsorption capacity of the high-entropy doped aluminum salt adsorbent in Example 2 was increased by 9.86%. Figure 7 This is a comparison chart of the cyclic adsorption capacity of the high-entropy doped 5% aluminum salt adsorbent prepared in Example 3 of the present invention and the aluminum salt adsorbent prepared in Comparative Example 1; (The chart is composed of...) Figure 7 It can be seen that, compared with the undoped aluminum salt adsorbent, the adsorption capacity of the high-entropy doped aluminum salt adsorbent in Example 3 was increased by 12.27%. Figure 8 This is a comparison chart of the cyclic adsorption capacity of the high-entropy doped 25% aluminum-based lithium adsorbent prepared in Example 4 of the present invention and the aluminum salt adsorbent prepared in Comparative Example 1. Figure 8 It can be seen that, compared with the undoped aluminum salt adsorbent, the adsorption capacity of the high-entropy doped aluminum salt adsorbent in Example 4 was increased by 15.64%. Table 2 shows the adsorption-desorption capacity data of the high-entropy doped aluminum salt adsorbent prepared in Examples 1-4 of the present invention, the single-doped aluminum-based lithium adsorbent prepared in Comparative Examples 2-6, and the undoped aluminum salt adsorbent prepared in Comparative Example 1.

[0127] Table 2

[0128] Sample Name Adsorption Capacity (mg / g) Comparative Example 1 LDH 6.856 Comparative Example 2 5% Zn-LDH 7.166 Comparative Example 3 5% Fe-LDH 7.263 Comparative Example 4 5% Mg-LDH 7.183 Comparative Example 5 5% Cu-LDH 7.382 Comparative Example 6 5% Co-LDH 7.502 Example 1 3% GS-LDH 7.313 Example 2 15% GS-LDH 7.532 Example 3 5% GS-LDH 7.697 Example 4 25% GS-LDH 7.928

[0129] As can be seen from Table 2, the adsorption capacity of adsorbents doped with Zn, Fe, Mg, Cu, and Co elements individually is lower than that of the high-entropy co-doped adsorbents prepared in Examples 1-4 of this invention. Taking Example 1 of this invention as an example, the novel high-entropy doped aluminum salt adsorbent in Example 1 of this invention improves the adsorption capacity of aluminum salt adsorbent by introducing three or more doping ions synergistically into the aluminum salt adsorbent, resulting in lattice distortion effect and cocktail effect. The specific mechanism analysis is as follows: (1) Optimization of crystal structure and surface active sites: Zn 2+ and Mg 2+ Reducing the positive charge density of the plates weakens the electrostatic attraction between Li+ and the plates, thus accelerating the ion exchange rate; Fe 3+ Introducing high energy density enhances redox activity and promotes electron transfer adsorption; the synergistic effect of multiple metals forms a high-entropy state, creates lattice defects, and optimizes surface active sites; (2) Enhanced surface electronic structure and adsorption affinity: the -OH group on the LDH surface is the key site for lithium adsorption; Fe3+ >Al 3+ >Mg 2+ The electronegativity gradient of Mg increases the protonation degree of some -OH groups, enhancing the repulsion of anions and simultaneously increasing the electrostatic attraction to cations. (3) Kinetic transport optimization: Mg 2+ The larger radius of Zn increases the interlayer spacing, reducing the resistance to Li+ diffusion; 2+ Doping increases the surface hydroxyl density, enhances the material's hydrophilicity, and makes it easier for solutions to penetrate into the internal channels, shortening the time to reach adsorption equilibrium; multi-metal doping generates surface charge heterogeneity (such as Fe). 3 Mg is positively charged 2+ (4) Special effects of multi-element doping: The synergistic effect of Zn / Fe / Mg optimizes the adsorption pathway: Mg 2+ Layer expansion → Zn 2+ Hydrophilic flow → Fe 3+ Valence state capture enables adsorption-diffusion synergistic enhancement, and the high-entropy state reduces the lattice free energy, thereby improving the structural stability of the material during cyclic adsorption-desorption and avoiding the collapse problem of traditional LDH.

[0130] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A high-entropy doped aluminum salt adsorbent, characterized in that, The high-entropy doped aluminum salt adsorbent has a molecular formula of LiAl x M y (OH) n Cl.mH2O; wherein: x is 1-5, y is 0-1, n is 6-15, m is 0.5-10; M is a mixture of at least three of Ag + , Mg 2+ , Ca 2+ , Cu 2+ , Co 2+ , Zn 2+ , Fe 3+ , Mn 2+ , Ni 2+ , Ti 4+ , and Zr 4+ .

2. A process for the preparation of high entropy doped aluminum salt adsorbents as claimed in claim 1, characterized in that, The preparation method comprises the following steps: S1: mixing a lithium salt, an aluminum salt and an M metal composite salt, dissolving them in deionized water, and ultrasonic mixing to obtain a first mixed salt solution; S2: preparing an alkaline solution, adding the alkaline solution into the first mixed salt solution dropwise, adjusting the pH value to 5-8, and stirring uniformly to obtain a second mixed salt solution; S3: heating and aging the second mixed salt solution to obtain a precursor precipitate; and sequentially performing centrifugal washing treatment and drying treatment on the precursor precipitate to obtain an adsorbent precursor; S4: mixing the adsorbent precursor with deionized water, and performing oscillation activation treatment to obtain a high-entropy doped aluminum salt adsorbent.

3. The preparation method according to claim 2, characterized in that, In step S1, the lithium salt is any one or more of lithium chloride, lithium nitrate, lithium sulfate, lithium carbonate and lithium hydroxide; the aluminum salt is any one or more of aluminum chloride, aluminum nitrate, aluminum sulfate, aluminum silicate and aluminum sulfide; and the M metal composite salt is a chloride or nitrate of at least three metals selected from Ag, Mg, Ca, Cu, Co, Zn, Mn, Ni, Fe, Ti and Zr.

4. The production method according to claim 2, characterized by, In step S1, the lithium salt and the aluminum salt are mixed in a molar ratio of Li:Al of 1:(0.5-3); and the M metal composite salt and the lithium salt are mixed in a molar ratio of M:Li of (1-20):(80-99).

5. The preparation method according to claim 2, characterized in that, In step S2, the dropwise adding speed of the alkaline solution into the first mixed salt solution is 0.5-10 ml / min, and the stirring speed is 100-500 r / min.

6. The preparation method according to claim 2, characterized in that, In step S2, the alkaline solution is any one of sodium hydroxide, potassium hydroxide, sodium aluminate, urea and ammonia water.

7. The preparation method according to claim 2, characterized in that, In step S3, the heating time of the heating and aging treatment is 0.1-4 h, and the heating temperature is 25-95℃; and the aging time is 0.1-4 h.

8. The preparation method according to claim 2, characterized in that, In step S3, the washing solution of the centrifugal washing treatment is any one of deionized water, ethanol and methanol; and the drying treatment is freeze-drying treatment.

9. The preparation method according to claim 2, characterized in that, In step S4, the solid-liquid ratio of the adsorbent precursor to deionized water is 40-200 g / L; the oscillation speed of the oscillation activation treatment is 10-1000 rpm, the oscillation time is 0.1-4 h, and the oscillation temperature is 25-35℃.

10. Use of a high-entropy doped aluminosalt adsorbent according to claim 1 for the extraction of lithium ions from a lithium-containing solution, characterized in that, The concentration of the aluminum salt lithium adsorbent applied in a lithium-containing solution is 0.01-10 g / L; and the lithium-containing solution is at least one of salt lake brine, concentrated lithium-containing old brine in a salt field, well water and seawater.

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