Lithium adsorbent and method for producing same

Abstract

A lithium adsorbent according to the present invention comprises a fluorine-doped aluminum-based layered double hydroxide, and is characterized in that a main peak appears at 2θ of 11.5° to 12.5° in an XRD analysis of the lithium adsorbent.

Description

Lithium adsorbent and method for manufacturing the same

[0001] This application claims priority to Korean Patent Application No. 10-2024-0189845 filed on December 18, 2024, and the contents of said priority application are all incorporated into this specification.

[0002] The present invention relates to a lithium adsorbent, specifically a fluorine-doped aluminum-based lithium adsorbent, and a method for manufacturing the same.

[0003] Lithium plays a key role in various advanced technology fields, such as electric vehicle batteries, portable electronic devices, and energy storage systems. In particular, due to the increasing demand for lithium-ion batteries, securing lithium resources and developing efficient recovery technologies have emerged as critical challenges.

[0004] Accordingly, the development of new adsorbents for the selective adsorption and recovery of lithium is actively underway, and among them, layered double hydroxide-based lithium adsorbents are attracting attention.

[0005] In the case of double-layered oxide-based lithium adsorbents, lithium is adsorbed into the internal pores of the adsorbent through weak interactions similar to Van der Waals forces.

[0006] Therefore, in the case of existing adsorbents, when desorption is performed using distilled water at high temperatures, an excessive amount of lithium is desorbed, and the structure of the adsorbent itself is transformed into a structure (Al(OH)3) from which the lithium contained therein has been removed, resulting in a decrease in adsorption capacity. Consequently, there was a problem in that a lithium-containing eluent such as LiCl had to be used instead of deionized water during desorption.

[0007] When using lithium-containing eluents such as LiCl, not only is there a concern about environmental pollution from wastewater, but costs are also increased because additional processes for concentration control and impurity removal may be required for reuse.

[0008] Therefore, there is a need to develop adsorbents that possess high structural stability during lithium desorption and enable efficient lithium recovery.

[0009] The present invention aims to provide an adsorbent capable of desorption using distilled water or deionized water and having excellent lithium adsorption efficiency.

[0010] In addition, the present invention aims to provide a lithium adsorbent that has high desorption stability and excellent affinity for lithium.

[0011] In addition, the present invention aims to provide a method for manufacturing a lithium adsorbent that can produce a lithium adsorbent with high structural stability and excellent adsorption capacity through a simple process.

[0012] The present invention provides a lithium adsorbent comprising a fluorine-doped aluminum-based layered double hydroxide, wherein a main peak appears at 2θ of 11.5 to 12.5° during XRD analysis.

[0013] In addition, the present invention provides a method for manufacturing a lithium adsorbent comprising the steps of: mixing an aluminum salt, an aluminum fluoride salt, and a lithium salt to obtain a mixed solution; and introducing the mixed solution into a sodium hydroxide solution to obtain a fluorine-doped aluminum-based layered double hydroxide; wherein, in the step of obtaining the fluorine-doped aluminum-based layered double hydroxide, the pH is maintained at a level greater than 10 and less than or equal to 12.

[0014] The lithium adsorbent according to the present invention has the advantage of being capable of desorption using distilled water and having superior adsorption capacity compared to an adsorbent not doped with fluorine.

[0015] In addition, the lithium adsorbent according to the present invention has the advantage of having high desorption stability and excellent affinity for lithium by introducing fluorine with high electronegativity to adsorb lithium more strongly.

[0016] In addition, the method for manufacturing a lithium adsorbent according to the present invention has the advantage of being able to manufacture a lithium adsorbent with high structural stability and excellent adsorption capacity through a simple process.

[0017] Figures 1 and 2 are XRD analysis results of lithium adsorbents according to the examples and comparative examples.

[0018] Figure 3 is the XPS analysis result of the lithium adsorbent prepared according to the example.

[0019] Figures 4 to 7 show the adsorption and desorption test results of lithium adsorbents according to examples and comparative examples.

[0020] Hereinafter, embodiments of the present invention will be described in detail. However, these are presented as examples and are not intended to limit the present invention, and the present invention is defined only by the scope of the claims set forth below.

[0021] In the present invention, when a part is described as "comprising" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components.

[0022]

[0023] Lithium Adsorbent

[0024] One aspect of the present invention relates to a lithium adsorbent comprising a fluorine-doped aluminum-based layered double hydroxide, wherein a main peak appears at 2θ of 11.5 to 12.5° during XRD analysis.

[0025] Specifically, the lithium adsorbent according to the present invention is a fluorine-doped aluminum-based lithium adsorbent.

[0026]

[0027] The lithium adsorbent according to the present invention may comprise an aluminum-based layered double hydroxide having a fluorine content of 0.1 to 12 weight% based on 100 weight% of the total. Specifically, the fluorine may be doped into the aluminum-based layered double hydroxide.

[0028] In short, the fluorine content in the fluorine-doped aluminum-based layered double hydroxide may be 0.1 to 12 weight%.

[0029]

[0030] In one embodiment of the present invention, the fluorine may replace a portion of the hydroxyl groups of the aluminum-based layered double hydroxide.

[0031] In short, the lithium adsorbent according to the present invention may have a structure in which the hydroxyl group (-OH) of an aluminum-based layered double hydroxide is partially substituted with fluorine (-F).

[0032] Specifically, in the present invention, “fluorine doping” means that fluorine is not inserted as an interlayer anion between the layered double hydroxides, but rather replaces the hydroxyl groups contained within the layered double hydroxides.

[0033]

[0034] Although I do not wish to be limited by theory, the fluorine has the advantage of being able to interact strongly with lithium compared to the hydroxyl group. Specifically, fluorine, which is a hard base ion, has excellent affinity for lithium, which is a hard acid ion. In short, the introduction of fluorine, which has high electronegativity, allows for stronger adsorption of lithium, thereby providing the advantage of high desorption stability.

[0035] In addition, the lithium adsorbent according to the present invention has excellent structural stability as structural collapse is suppressed even at high temperatures by substituting the hydroxyl group with the fluorine, in other words, by fluorine doping, and has excellent adsorption efficiency due to high affinity with lithium, and has excellent advantages such as easy desorption with high-temperature distilled water, for example, distilled water at about 40°C, without using a lithium-containing eluent such as LiCl.

[0036]

[0037] The above fluorine can be substituted with respect to the hydroxyl group in a range of 0.3 to 25%, specifically in a range of 0.8 to 15%, and more specifically in a range of 3.5 to 10%.

[0038]

[0039] The lithium adsorbent according to the present invention shows a main peak at 2θ of 11.5 to 12.5° during XRD analysis.

[0040] In another embodiment of the present invention, the lithium adsorbent according to the present invention may show a main peak at 2θ of 11.8 to 12.5°, specifically 12 to 12.5°, immediately after synthesis, in other words, when hydroxide anions are present as interlayer anions. The position of the peak may vary as the size differs depending on the type of interlayer anion inserted.

[0041]

[0042] In the present invention, the numerical value for the diffraction angle 2θ in XRD analysis may be in the range of ±1.0°, and specifically, in the range of ±0.5°.

[0043]

[0044] In another embodiment of the present invention, the lithium adsorbent may be represented by the following chemical formula 1.

[0045] [Chemical Formula 1]

[0046] xLiA·2Al(OH) 3-y F y ·nH2O

[0047] In the above chemical formula 1,

[0048] A is Cl - , OH - , I - , F - , Br - , NO3 - SO4 2- , CO3 2- and PO 4- It is one or more anions selected from the group consisting of, and

[0049] x is a value greater than 0 and less than or equal to 1.5, and

[0050] y is a value between 0.01 and 0.6.

[0051]

[0052] In another embodiment of the present invention, the interplanar distance of the crystal structure in the layered double hydroxide may be 7.0 to 8.0 Å.

[0053] In the present invention, the “interplanar distance” can be obtained using XRD analysis results and Bragg’s law.

[0054]

[0055] [Equation 1]

[0056] nλ = 2dsinθ

[0057] (n: diffraction order, λ: X-ray wavelength, d: interplane distance based on Miller exponent)

[0058]

[0059] Specifically, the interplanar distance of the crystal structure in the layered double hydroxide may be 7.2 to 7.8 Å, more specifically 7.37 to 7.54 Å.

[0060]

[0061] The fact that the interplanar distance of the crystal structure of the lithium adsorbent according to the present invention satisfies the above range implies that fluorine has substituted a portion of the hydroxyl groups, resulting in greater interlayer interaction than before the substitution. Therefore, if the interplanar distance of the crystal structure of the lithium adsorbent satisfies the above range, it can be determined that fluorine doping has occurred. Due to the high lithium affinity of fluorine, there is an excellent advantage in that lithium ions are efficiently adsorbed and do not desorb excessively. In other words, it is desirable that structural stability and selectivity are maximized during the lithium ion adsorption and desorption process.

[0062]

[0063] Method for manufacturing lithium adsorbent

[0064] Another aspect of the present invention relates to a method for manufacturing a lithium adsorbent, comprising the steps of: mixing an aluminum salt, an aluminum fluoride salt, and a lithium salt to obtain a mixed solution; and introducing the mixed solution into a sodium hydroxide solution to obtain a fluorine-doped aluminum-based layered double hydroxide, wherein in the step of obtaining the fluorine-doped aluminum-based layered double hydroxide, the pH is maintained at a level greater than 10 and less than or equal to 12.

[0065] Specifically, the method for manufacturing a lithium adsorbent according to the present invention has the advantage of easily manufacturing the aforementioned lithium adsorbent through a simple process.

[0066]

[0067] A method for manufacturing a lithium adsorbent according to the present invention comprises the step of mixing an aluminum salt, an aluminum fluoride salt, and a lithium salt to obtain a mixed solution.

[0068] In another embodiment of the present invention, the aluminum salt may comprise one or more selected from the group consisting of aluminum chloride, aluminum hydroxide, aluminum nitrate, aluminum sulfate, and aluminum acetate.

[0069] The above aluminum salt may specifically be aluminum chloride.

[0070] When the above aluminum salt is aluminum chloride, it is desirable because it allows for the production of a lithium adsorbent having a uniform structure due to its high solubility.

[0071] Specifically, the aluminum chloride may be included in the form of an anhydrous or hydrated form (AlCl3·6H2O).

[0072]

[0073] In another embodiment of the present invention, the aluminum fluoride salt may comprise one or more selected from the group consisting of creolite (Na3AlF6), aluminum fluoride (AlF3), and aluminum tetrafluoride (AlF4).

[0074] Specifically, the above aluminum fluoride salt may be creolite.

[0075] The above chryolite is inexpensive and has a structure in which aluminum and fluorine are already bonded in 6 coordination positions, which is advantageous for forming an adsorbent structure and is suitable as a source of fluorine.

[0076]

[0077] The above lithium salt may include one or more selected from the group consisting of lithium chloride, lithium hydroxide, lithium carbonate, lithium phosphate, lithium nitrate, lithium sulfate, and lithium acetate.

[0078] The above lithium salt provides lithium ions during the reaction process and is inserted into the aluminum-based layered double hydroxide structure, thereby creating a space for lithium ions and paired anions to enter and exit, and thus functions as an adsorbent.

[0079] Specifically, the above lithium salt may be lithium chloride.

[0080] When the above lithium salt is lithium chloride, it has the advantage of enabling a uniform supply of lithium ions during the lithium adsorbent formation reaction due to its higher solubility compared to other lithium salts. Therefore, it helps to increase the synthesis efficiency of the lithium adsorbent and obtain a lithium adsorbent with a uniform particle size. In addition, it offers the advantage of improved economic feasibility due to its relatively low cost.

[0081]

[0082] The above aluminum salt, the above aluminum fluoride salt, and the above lithium salt can be mixed according to the chemical stoichiometric ratio.

[0083] Specifically, the aluminum salt, the aluminum fluoride salt, and the lithium salt may be added according to the stoichiometric ratio to satisfy the compositional formula of Chemical Formula 1.

[0084]

[0085] The above mixed solution may further contain a solvent and / or an acid / base.

[0086] The above solvent may include one or more selected from the group consisting of water, ethanol, methanol, and butanol.

[0087] In addition, the acid / base may include one or more of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, sodium hydroxide, lithium hydroxide, and potassium hydroxide.

[0088] The above solvent may specifically be deionized water.

[0089] The deionized water may be included in an amount of 20 to 95 parts by weight, preferably 70 to 90 parts by weight, based on 100 parts by weight of the total mixed solution.

[0090] When the deionized water is included within the above range, the mixed solution has an appropriate viscosity, which not only improves processability but also facilitates the reaction within the mixed solution during the step of adding it to the sodium hydroxide solution described later, thereby providing the advantage of obtaining a uniform form of lithium adsorbent, which is desirable.

[0091]

[0092] The step of obtaining the above mixed solution can be performed for 0.5 to 4 hours, preferably 0.5 to 1.5 hours, and more preferably 0.7 to 1 hour.

[0093] If the step of obtaining the above mixed solution is performed within the above time range, it is desirable that the reaction is sufficiently carried out to increase the yield.

[0094]

[0095] The above mixing may be performed by stirring, but is not limited thereto.

[0096] For example, the above mixing can be performed by stirring at 80 to 1000 RPM, preferably 100 to 350 RPM, more preferably 150 to 300 RPM.

[0097] When the above mixing is performed within the above RPM range, it is desirable that the reaction can uniformly dissolve the aluminum salt, the aluminum fluoride salt, and the lithium salt.

[0098]

[0099] The above mixing can be performed at room temperature, specifically at a temperature of 20 to 25°C.

[0100]

[0101] In another embodiment of the present invention, the method may further include the step of obtaining the mixed solution; and the step of filtering the mixed solution to remove impurities thereafter, but is not limited thereto.

[0102] For example, the above filtration can be performed using a membrane filter, filter paper, vacuum filtration device, pressure filtration device, centrifugal filtration device, etc., but is not limited thereto.

[0103] If the above filtration is further performed, it is desirable to improve the purity of the mixed solution, thereby improving the quality of the finally produced lithium adsorbent.

[0104]

[0105] Step of obtaining fluorine-doped aluminum-based layered double hydroxide

[0106] A method for manufacturing a lithium adsorbent according to the present invention comprises the step of introducing the aforementioned mixed solution into a sodium hydroxide solution to obtain a fluorine-doped aluminum-based layered double hydroxide; wherein, in the step of obtaining the fluorine-doped aluminum-based layered double hydroxide, the pH is maintained at a level greater than 10 and less than or equal to 12.

[0107] Specifically, the mixed solution may be introduced such that the pH of the sodium hydroxide solution into which the mixed solution is introduced is greater than 10 and less than or equal to 12.

[0108] Although we do not wish to be limited by theory, when the above pH is 10 or lower, there is a problem of low yield of the desired lithium adsorbent because a material with a doyleite structure is produced, or a lithium adsorbent mixed with a layered double hydroxide (LDH) and a doyleite structure is produced.

[0109] Specifically, in the case of the doylite structure, there are no lithium cations and paired anions, so the interlayer distance is close, and consequently, it is difficult for lithium to enter and exit, so there is a problem in that a lithium adsorbent with the desired effect cannot be obtained.

[0110] When the pH exceeds 12, there is a problem where aluminum is leached out due to the structural stability of the layered double hydroxide, resulting in a decrease in yield.

[0111] Accordingly, in the present invention, a desired fluorine-doped aluminum-based layered double hydroxide is obtained by controlling the pH in the step of obtaining the fluorine-doped aluminum-based layered double hydroxide.

[0112]

[0113] The sodium hydroxide solution may have a concentration of 1.0 to 5.0 M, preferably 1.0 to 2.5 M, more preferably 1.5 to 2.5 M, but is not limited thereto.

[0114] However, if the concentration of the sodium hydroxide solution satisfies the above range, it is desirable that a change to the desired pH occurs rapidly, thereby forming an atmosphere in which the fluorine-doped aluminum-based layered double hydroxide can react rapidly.

[0115]

[0116] In another embodiment of the present invention, the step of obtaining the fluorine-doped aluminum-based layered double hydroxide may be performed at a temperature of 20 to 100°C.

[0117] This can be carried out by adding the mixed solution to the sodium hydroxide solution at a temperature preferably from 20 to 100°C, preferably from 40 to 90°C, and more preferably from 60 to 80°C.

[0118] When the above mixed solution is introduced into a sodium hydroxide solution within the above temperature range, it is desirable that the fluorine-doped aluminum-based layered double hydroxide is rapidly formed while the temperature for lithium salt insertion is satisfied.

[0119]

[0120] The above mixed solution may be introduced in a constant amount at a constant rate over a period of 0.5 to 2 hours. For example, it may be introduced at a rate of 3 to 20 mL / min, preferably 5 to 18 mL / min, and more preferably 7 to 15 mL / min, but is not limited thereto as this may depend on the synthesis scale.

[0121] When the above mixed solution is introduced at a rate satisfying the above range, it is desirable to be able to form a fluorine-doped aluminum-based layered double hydroxide with high structural stability while shortening the process time.

[0122]

[0123] Specifically, under stirring of the sodium hydroxide solution, the mixed solution can be added until the pH becomes greater than 10 and less than or equal to 12, and then, when the pH satisfies the desired range, the addition of the mixed solution can be stopped and stirring can be continued.

[0124] The above stirring can be performed by stirring at 80 to 800 RPM, preferably 100 to 350 RPM, and more preferably 150 to 300 RPM.

[0125] When the above stirring is performed within the above RPM range, the formation reaction of fluorine-doped aluminum-based layered double hydroxide occurs sufficiently while shortening the process time, thereby increasing the structural yield and enabling the production of an adsorbent with uniform particle size.

[0126] At this time, during the step of stopping the input of the above-mentioned mixed solution and stirring, the temperature can be maintained within the aforementioned temperature range.

[0127]

[0128] In another embodiment of the present invention, the method may further include the step of obtaining the fluorine-doped aluminum-based layered double hydroxide; and the step of washing and drying the fluorine-doped aluminum-based layered double hydroxide.

[0129] Specifically, the above-mentioned fluorine-doped aluminum-based layered double hydroxide can be separated into solid and liquid phases, and then washed with water to remove surface impurities.

[0130] At this time, it can be washed with fresh or distilled water.

[0131]

[0132] The washed fluorine-doped aluminum-based layered double hydroxide can be dried at a temperature in the range of 20°C to 105°C, preferably 40°C to 100°C, more preferably 60°C to 80°C, for 12 to 48 hours, preferably 12 to 24 hours.

[0133] When the drying temperature is within the above range, it is advantageous to prevent the problem of structural destruction and reduced adsorption performance at high temperatures while ensuring that the drying time does not take too long.

[0134]

[0135] The dried fluorine-doped aluminum-based layered double hydroxide may further include a step of washing using a salt solution.

[0136] At this time, washing can be performed to remove residual lithium salt.

[0137] The above salt solution may be, for example, one or more salts selected from the group consisting of sodium, potassium, magnesium, calcium, and lithium, specifically a solution containing one or more of sodium chloride solution, potassium chloride solution, magnesium chloride, calcium chloride solution, and lithium chloride.

[0138] The method may further include the step of separating solids and liquids, passing a medium through the solution to remove the salt solution, and desorbing lithium to activate the lithium adsorption site.

[0139]

[0140] The lithium adsorbent according to the present invention has the advantage of being capable of desorption using a lithium-containing solution, distilled water, deionized water, etc., and having excellent lithium adsorption efficiency. In particular, the lithium adsorbent according to the present invention has the advantage of high desorption stability even when using distilled water, deionized water, more specifically high-temperature distilled water, deionized water, etc., without using a lithium-containing solution.

[0141]

[0142] Preferred embodiments and comparative examples of the present invention are described below. However, the following examples are merely preferred embodiments of the present invention, and the present invention is not limited to the following examples.

[0143]

[0144]

[0145] Examples and Comparative Examples

[0146] Examples

[0147] 1.2 L of deionized water (DI water), 625 mmol of AlCl3·6H2O, 209 mmol of Na3AlF6, and 417 mmol of LiCl were dissolved by stirring for 1 hour, and then filtered using vacuum filtration.

[0148] 1 L of 2 M NaOH solution was placed in a double-jacketed water bath at 80°C and stirred.

[0149] After the temperature of the 2 M NaOH solution reached 80℃, the clear mixed solution separated from the solid was added at a rate of 10 mL / min.

[0150] Stopped adding at pH 10.3 and stirred for another 2 hours at 80℃.

[0151] Afterward, the solid (lithium adsorbent) obtained by solid-liquid separation was washed with 1 L of water and dried at 80°C for 12 hours.

[0152]

[0153] Afterward, the lithium adsorbent was prepared by washing with an NaCl solution, separating the solid and liquid phases, and desorbing with water at 20 BV to partially desorb lithium and activate the structure.

[0154]

[0155] Comparative Example 1

[0156] A lithium adsorbent was prepared using the same method as in the example, except that the pH was maintained at 7.

[0157]

[0158] Comparative Example 2

[0159] A lithium adsorbent was prepared in the same manner as in the example, except that the pH was maintained at 9.

[0160]

[0161] Comparative Example 3

[0162] A lithium adsorbent was prepared in the same manner as in the example, except that the pH was maintained at 10.

[0163]

[0164] Experimental Example

[0165] (1)XRD analysis

[0166] The lithium adsorbents prepared according to the examples and comparative examples were analyzed by XRD (Rigaku D, Cu Kα radiation, λ = 1.54060), and the results are shown in Figure 1.

[0167] Referring to Figure 1, it can be seen that the lithium adsorbent prepared according to the example exhibits a layered double hydroxide structure (LDH). On the other hand, in Comparative Example 1, no LDH structure was observed, and in Comparative Examples 2 and 3, although an LDH structure was observed, a doyleite structure was also observed, so a pure layered double hydroxide could not be obtained.

[0168]

[0169] In addition, detailed data (PXRD) of the XRD analysis results of the lithium adsorbent prepared according to the example and the non-fluorine-doped LiOH·2Al(OH)3·nH2O lithium adsorbent (commercial product, ICDD PDF Card No. 01-081-1573) are shown in Figure 2, and the main peak and interplanar distance were measured.

[0170] The main peak of LiOH·2Al(OH)3·nH2O appeared at 11.72°, and when substituted into the value of nλ = 2dsinθ (λ = wavelength of X-ray, d = interplanar distance) according to Bragg's law, d, the interplanar distance, was measured to be 7.55 Å.

[0171]

[0172] The lithium adsorbent prepared according to the example showed a main peak at 12° (2θ), and the interplanar distance according to Bragg's law was measured to be 7.37 Å.

[0173] Referring to Figure 2, it can be seen that in the case of the lithium adsorbent prepared according to the example, the peak is shifted at a higher angle compared to LiOH·2Al(OH)3·nH2O. This is presumed to be because the interlayer spacing was reduced compared to before F doping due to the high charge of F.

[0174]

[0175] (2) XPS analysis

[0176] The XPS (VG SCIENTIFIC instrument) analysis results of the lithium adsorbent prepared according to the example are shown in Figure 3.

[0177] Specifically, to remove surface contamination, 20 nm etching was performed using the Ar etching method, and then XPS was measured. In the XPS spectrum of the adsorbent prepared according to the measured example, a peak near 685 eV can be identified, which corresponds to the 1s orbital of an F atom. Through this, it can be seen that fluorine is present in the lithium adsorbent prepared according to the example.

[0178]

[0179] (3) Elemental analysis

[0180] The results of the elemental analysis of the lithium adsorbent prepared according to the example are shown in Table 1 below. Specifically, to quantitatively analyze the ratio of metal cations, the composition of the adsorbent powder was confirmed using Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES), and the anion, specifically the fluorine content, was measured using Combustion-Ion Chromatography (C-IC), and the results are shown in Table 1 below.

[0181]

[0182] wt.%ICP-OESC-ICLi3.11-Al24.75-F-3.58

[0183] Referring to Table 1, the adsorbent prepared according to the example is 0.98LiOH·2Al(OH) 2.81 F .0.19 · As an H2O structure, it can be seen that 6.65% of the -OH in the layer is substituted with -F.

[0184]

[0185] (4) High temperature structural stability

[0186] 100 mg and 1 g of the lithium adsorbent prepared according to the example and LiOH·2Al(OH)3·nH2O, respectively, were added to 100 mL of DI water at 80°C, and the Al(OH)3 ratio over time as shown in Table 2 below was measured.

[0187] Specifically, the adsorbents after each time elapsed following immersion were dried in the same manner, and XRD quantitative analysis was performed and the Al(OH)3 ratio was measured. The results are shown in Tables 2 and 3 below, respectively.

[0188] Solid-Liquid Ratio Time (min) Al(OH)3 Ratio (%) Example 10 g / L 001,4405.5

[0189] Solid-Liquid Ratio (min) Al(OH)3 Ratio (%) LiOH·2Al(OH)3·nH2O1 g / L 0 0 10 17 20 56 60 78

[0190] Generally, the amount of lithium desorption increases as the solid-liquid ratio (amount of desorption eluent / weight of adsorbent) increases. Referring to Tables 2 and 3 above, it can be seen that the lithium adsorbent prepared according to the example has a low Al(OH)3 ratio of 5.5% even after 1,440 minutes, compared to the LiOH·2Al(OH)3·nH2O material, indicating that there is less structural deformation due to excessive lithium desorption.

[0191]

[0192] (5) Adsorption / Desorption Test

[0193] Adsorption and desorption tests were performed using the lithium adsorbent prepared according to the example and the most commonly used LiCl·2Al(OH)3·nH2O lithium adsorbent.

[0194] Specifically, a lithium solution as shown in Table 4 below was prepared, and the lithium adsorbents of the Example and LiCl·2Al(OH)3·nH2O were respectively filled into columns. At 40°C, the lithium solution was flowed through the adsorbent at a flow rate of 10 BV / h, amounting to 13 times the bed volume (BV) of the adsorbent (13 BV). The adsorption curves of the lithium adsorbent prepared according to the Example and the LiCl·2Al(OH)3·nH2O lithium adsorbent are shown in Figures 4 and 5, respectively. Subsequently, the desorption curve results, which measured the lithium concentration in the desorption solution after flowing deionized water at 40°C at a rate of 22 BV, are shown in Figures 6 and 7, respectively. At this time, C in Figures 4 and 5 t / C0 represents the adsorption performance as the reduced concentration of lithium relative to the initial lithium-containing solution concentration, and in Figures 6 and 7, the y-axis represents the desorption performance as the concentration of desorbed lithium.

[0195]

[0196] Saline composition LiNaKCaB mg / L 360 44,000 16,500 30,400 390

[0197] Referring to Figures 4 and 6, when the lithium adsorbent prepared according to the example was used, the adsorption amount was 5.8 mg / g and the desorption amount was 5.8 mg / g. On the other hand, referring to Figures 5 and 7, when the LiCl·2Al(OH)3·nH2O lithium adsorbent was used, the adsorption amount was 2.7 mg / g and the desorption amount was 6.2 mg / g, confirming that the amount desorbed was in excess of the adsorption amount. In the case of the adsorbent prepared according to the example, the adsorption efficiency is excellent at 40°C, and it can be seen that the amount desorbed is stable in proportion to the amount adsorbed.

[0198]

[0199] The present invention is not limited to the above embodiments and can be manufactured in various different forms, and those skilled in the art will understand that the invention can be implemented in other specific forms without changing the technical concept or essential features of the invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive.

Claims

It includes fluorine-doped aluminum-based layered double hydroxide, In XRD analysis, a main peak appears at 2θ between 11.5 and 12.5°, Lithium adsorbent. In paragraph 1, A lithium adsorbent represented by the following chemical formula 1: [Chemical Formula 1] xLiA·2Al(OH) 3-y F y ·nH2O In the above chemical formula 1, A is Cl - , OH - , I - , F - , Br - , NO3 - SO4 2- , CO3 2- and PO 4- It is one or more anions selected from the group consisting of, and x is a value greater than 0 and less than or equal to 1.5, and y is a value between 0.01 and 0.

6. In paragraph 1, A lithium adsorbent having an interplanar distance of the crystal structure in the above-mentioned layered double hydroxide of 7.0 to 8.0 Å. In paragraph 1, A lithium adsorbent in which the main peak appears at 2θ of 12 to 12.5° during XRD analysis. In paragraph 1, The above fluorine is a lithium adsorbent that replaces part of the hydroxyl group of the above aluminum-based layered double hydroxide. A step of obtaining a mixed solution by mixing an aluminum salt, an aluminum fluoride salt, and a lithium salt; and A step of adding the above mixed solution to a sodium hydroxide solution to obtain a fluorine-doped aluminum-based layered double hydroxide; Includes, In the step of obtaining the above fluorine-doped aluminum-based layered double hydroxide; wherein the pH is maintained at greater than 10 and less than or equal to 12, Method for manufacturing a lithium adsorbent. In paragraph 6, A method for manufacturing a lithium adsorbent, wherein the aluminum salt comprises one or more selected from the group consisting of aluminum chloride, aluminum hydroxide, aluminum nitrate, aluminum sulfate, and aluminum acetate. In paragraph 6, A method for manufacturing a lithium adsorbent, wherein the aluminum fluoride salt comprises one or more selected from the group consisting of chryolite, aluminum fluoride, and aluminum tetrafluoride. In paragraph 6, A method for manufacturing a lithium adsorbent, wherein the lithium salt comprises one or more selected from the group consisting of lithium chloride, lithium hydroxide, lithium carbonate, lithium phosphate, lithium nitrate, lithium sulfate, and lithium acetate. In paragraph 6, A method for manufacturing a lithium adsorbent, wherein the step of obtaining the above-mentioned fluorine-doped aluminum-based layered double hydroxide is performed at a temperature of 20 to 100°C. In paragraph 6, The step of obtaining the above-mentioned fluorine-doped aluminum-based layered double hydroxide; thereafter, A method for manufacturing a lithium adsorbent, further comprising the step of washing and drying the above-mentioned fluorine-doped aluminum-based layered double hydroxide.

Images