Extracting agent for efficiently separating and extracting scandium and preparation method thereof

Abstract

The invention provides an extracting agent for efficiently separating and extracting scandium and a preparation method thereof, and relates to the field of solvent extraction. The preparation method comprises the following steps: mixing DMF (Dimethyl Formamide), an aminopolycarboxylic acid chelating agent, triethylamine and 1-hydroxybenzotriazole in proportion under an ice salt bath condition, uniformly stirring, adding 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride in batches for activation, then adding aliphatic secondary amine, heating, and reacting for 20-30 hours to obtain a reaction solution; after the reaction liquid is cooled, suction filtration is performed, deionized water is added, and ethyl acetate is adopted for extraction; then washing, drying and carrying out rotary evaporation to obtain an oily substance; adding petroleum ether into the oily substance, heating and stirring, cooling, removing impurities, and eluting to obtain the extracting agent. The extracting agent prepared by the method only contains four elements of C, H, O and N, meets the standard of an environment-friendly green extracting agent, not only can realize efficient extraction of scandium ions in a wider acidity range, but also has environment-friendly performance, and has good economic value.

Description

Technical Field

[0001] This invention relates to the field of solvent extraction, and more specifically, to an extractant for the efficient separation and extraction of scandium and its preparation method. Background Technology

[0002] Scandium is a rare earth element known as the "miracle metal," characterized by its low density, good ductility, excellent catalytic properties, and good electrical conductivity. This element is widely used in important fields such as aerospace, nuclear technology, metallurgy, and electric light sources. The average abundance of scandium in the Earth's crust reaches 22 g / t. However, its distribution is scattered, with high-scandium deposits being rare, and it often coexists with other ores. During resource extraction from ores, scandium often enters the slag and wastewater, resulting in a higher scandium content in secondary resources than in the ore. This leads to scandium being primarily extracted from low-grade ores and secondary resources, such as uranium ore, rare earth ores, tungsten slag, laterite nickel ore, red mud, and titanium dioxide waste acid. This results in complex extraction processes, low recovery rates, and high costs. With the widespread application of scandium in new materials, new energy, information technology, aerospace, and military defense, the demand for scandium will continue to increase, making the stable supply of scandium a crucial issue.

[0003] Currently, commonly used extractants in metal separation mainly include neutral phosphorus extractants, acidic phosphorus extractants, carboxylic acids, amines, chelates, and synergistic extraction systems. In the separation and extraction of scandium, acidic phosphorus extractants such as P204 (D2EHPA) and P507 (HEHEHP) are widely used due to their high extraction capacity and good selectivity. For example, P204 can achieve an extraction rate of over 99% for scandium under suitable acidity, making it suitable for recovering scandium from secondary resources such as red mud and titanium dioxide waste acid. However, this type of extractant is prone to emulsification and slow phase separation, increasing operating costs and process complexity. Furthermore, traditional acidic phosphorus extractants contain elements such as phosphorus and sulfur, which may produce harmful substances during incineration or degradation, posing potential environmental risks.

[0004] In recent years, to improve the environmental performance of extractants, researchers have developed green extractants containing only carbon, hydrogen, oxygen, and nitrogen (CHON), such as some carboxylic acid and amine extractants. These extractants have advantages such as complete incineration and environmental friendliness, but their extraction capacity is usually weak and their applicable acidity range is narrow. They are difficult to maintain good extraction performance under high acidity conditions (such as molar levels), which limits their application in the treatment of strongly acidic industrial wastewater.

[0005] Furthermore, it is currently difficult to directly recover scandium from mineral resources. It is typically recovered as a byproduct in other metal production processes, from tailings or industrial residues, such as those from uranium and tungsten formation, laterite nickel ore, bauxite slag, and titanium dioxide wastewater. Laterite ore typically contains over 30 g / t, reaching up to approximately 600 g / t, making it a very promising scandium resource. However, according to literature, laterite ore also contains significant amounts of elements such as Mg, Al, Fe, Co, Ni, and Sc. Therefore, how to specifically separate scandium is a major challenge that urgently needs to be addressed.

[0006] In summary, existing technologies lack an extractant that possesses both high extraction capacity and good environmental adaptability (suitable for high acidity conditions) and whose molecular structure contains only C, H, O, and N. Particularly in the extraction of Sc, achieving efficient and selective extraction in high acidity media while maintaining operational economy remains a pressing technical challenge in this field. Summary of the Invention

[0007] The purpose of this invention is to provide an efficient extractant for separating and extracting scandium and its preparation method. The extractant prepared by this method contains only C, H, O, and N, and is a green extractant. Furthermore, it is effective against Sc over a wide acidity range. 3+ It has a high extraction capacity.

[0008] The technical problem solved by this invention is achieved by the following technical solution.

[0009] On the one hand, embodiments of this application provide an extractant for the efficient separation and extraction of scandium, the chemical formula of which is shown in Formula I and / or Formula II: Formula I; Formula II; Where R1 and R2 each represent carbon chain lengths of C4-C. 12 alkane chain.

[0010] Secondly, embodiments of this application provide a method for preparing the above-mentioned highly efficient extractant for separating and extracting scandium, comprising the following steps: S1: DMF, amino polycarboxylic acid chelating agent, triethylamine and 1-hydroxybenzotriazole were mixed in proportion under ice-salt bath conditions and stirred evenly. Then, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride was added in batches for activation. Then, an aliphatic secondary amine was added, and the mixture was heated and reacted for 20-30 hours to obtain the reaction solution. S2: After the reaction solution cools, filter it, add deionized water and extract with ethyl acetate; then wash, dry and rotary evaporate to obtain an oily substance; S3: Add petroleum ether to the oily substance, heat and stir, cool, remove impurities and wash to obtain the extractant.

[0011] Furthermore, in step S1, the molar ratio of DMF, aminopolycarboxylic acid chelating agent, triethylamine, 1-hydroxybenzotriazole, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and aliphatic secondary amine is (90-95):(0.6-0.7):(11-14):(10-13):(10-14):(10-14).

[0012] Furthermore, the aminopolycarboxylic acid chelating agent is any one or more of ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, aziridinetriacetic acid, cyclohexanediaminetetraacetic acid, or ethylene glycol diethyl ether diaminetetraacetic acid.

[0013] Furthermore, the aliphatic secondary amine is any one or more of di-n-butylamine, di-n-octylamine, dihexylamine, diheptylamine, or didecylamine.

[0014] Furthermore, in step S2, the extraction is performed 3 times and the washing is performed 3 times.

[0015] Furthermore, in step S3, the elution method is silica gel column chromatography separation, and gradient elution is performed using petroleum ether / ethyl acetate at a volume ratio of (2-5):1.

[0016] Compared with the prior art, the embodiments of the present invention have at least the following advantages or beneficial effects: 1. The extractant prepared by this invention contains only four elements: C, H, O, and N, which meets the standards for environmentally friendly green extractants. It can achieve efficient extraction of scandium ions over a wide acidity range, while also being environmentally friendly and having good economic value. 2. The extractant prepared by this invention can achieve specific extraction of scandium ions among a variety of heteroions, which greatly improves the extraction efficiency of scandium and better meets the industrial demand for efficient extraction of scandium. Attached Figure Description

[0017] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a graph showing the changes in the extraction effect of three extractants on scandium ions in the embodiments of the present invention; Figure 2 Extractant L in the embodiments of the present invention ⅡA graph showing the changes in the specific extraction effect; Figure 3 Extractant L in the embodiments of the present invention Ⅰ FT-IR analysis plot; Figure 4 L in the embodiments of the present invention Ⅱ FT-IR analysis plot; Figure 5 L in the embodiments of the present invention Ⅲ FT-IR analysis plot. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0020] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to specific embodiments.

[0021] For ease of understanding, in the following embodiments, each English character represents: DMF: N, N -Dimethylformamide; EDCl: 1-Ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride; HOBT: 1-Hydroxybenzotriazole; NEt 3： Triethylamine.

[0022] Example 1 This embodiment provides a detailed method for preparing an extractant for the efficient separation and extraction of scandium. The chemical formula of the preparation process is as follows:

[0023] Specifically, it includes the following steps: S1: Under ice-salt bath conditions at 0-5℃, 700 mL of DMF, 20 g of ethylenediaminetetraacetic acid (68.4 mmol, 1.0 eq), 28.4 g of triethylamine (280.4 mmol, 4.1 eq), and 37.0 g of 1-hydroxybenzotriazole (273.7 mmol, 4.0 eq) were mixed and stirred evenly. Then, 52.5 g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (273.7 mmol, 4.0 eq) was added in portions. After the addition was complete, the mixture was stirred and activated for 1 h. Then, 35.4 g of di-n-butylamine (273.7 mmol, 4.0 eq) was slowly added to the mixture while stirring. After the addition was complete, the temperature was slowly raised to 50℃ and the reaction was kept at the open temperature for 24 h to obtain the reaction solution. In this reaction, the condensing agent EDCl first reacts with the carboxyl group to generate a highly reactive O-acylisourea intermediate. Subsequently, HOBT acts as a catalyst to convert the unstable O-acylisourea intermediate into a more stable active lipid. Finally, under the condition of NEt3 as an acid-binding agent, the secondary amine acts as a nucleophile to attack the carbonyl carbon of the active lipid. After passing through a tetrahedral intermediate, an amide bond is formed, releasing HOBT to obtain the target product.

[0024] S2: After the reaction solution cools, filter to remove insoluble matter. Add 300 mL of deionized water to the reaction solution and extract three times with 100 mL of ethyl acetate (EA). Combine the organic phases. Wash the organic phase three times with 0.10 mol / L HCl solution (100 mL × 3), saturated Na2CO3 solution (100 mL × 3), and saturated NaCl solution (100 mL × 3), respectively. After drying with anhydrous Na2SO4, remove EA by rotary evaporation to obtain an oily substance. S3: Add 100 mL of petroleum ether to the above oily substance, heat and stir briefly, cool, and then filter to remove a large amount of solid impurities. After removing PE by rotary evaporation, a yellow oily crude product is obtained. The yellow oily crude product is separated by silica gel column chromatography using a gradient elution of a mixture of petroleum ether and ethyl acetate at a volume ratio of 2:1. The resulting light yellow oily product is the extractant, denoted as extractant L. Ⅰ The extractant is N, N, N′, N′, N′′, N′′, N′′′, N′′′ - Octabutylethylenediaminetetraacetamide, with a yield of 48%, has the structural formula shown in Formula III: Formula III; Please refer to Figure 3 Extractant L Ⅰ The specific structural characterization data are as follows: 1 H NMR (400 MHz, CDCl3): δ 3.59 (s, 8H), 3.23 (q,J = 7.5 Hz, 16H), 2.91(s, 4H), 1.50-1.42 (m, 16H), 1.33-1.24 (m, 16H), 0.95-0.85 (m, 24H); ESI-HRMS (C 42 H 85 N6O4 + (Calculated value) m / z : 737.6625 (737.6627); FT-IR ( ν / cm -1 ): 2954, 2928 (–CH3, –CH2, CH stretching vibration), 2865 (–CH3, CH stretching vibration), 1640 (C=O stretching vibration), 1458, 1373 (–CH3, CH bending vibration), 1109 (CN stretching vibration), 733 (–CH2–, CH bending vibration).

[0025] Example 2 This embodiment provides another method for preparing an extractant, which is... N, N, N′, N′, N′′, N′′, N′′′, N′′′ -Octa-octylethylenediaminetetraacetamide, the preparation steps are basically the same as those in Example 1, the only difference being: In step S1, 35.4 g of di-n-butylamine is replaced with 65.9 g of di-n-octylamine; In step S3, a gradient elution is performed using a mixture of petroleum ether and ethyl acetate at a volume ratio of 5:1. The resulting extractant is denoted as extractant L. Ⅱ The yield is 51%, and its structural formula is shown in Formula IV: Formula IV; Please refer to Figure 4 Extractant L Ⅱ The specific structural characterization data are as follows: 1 H NMR (400 MHz, CDCl3): δ 3.58(s, 8H), 3.23-3.19 (m, 16H), 2.90 (s,4H), 1.47 (p, J = 7.2 Hz, 16H), 1.29-1.23 (m, 80H), 0.89-0.84 (m, 24H); ESI-HRMS (C 74 H 149 N6O4 +(Calculated value) m / z : 1186.1638 (1186.1635); FT-IR ( ν / cm -1 ): 2920, 2851 (–CH2, CH stretching vibration), 2865 (–CH3, CH stretching vibration), 1645 (C=O stretching vibration), 1461, 1377 (–CH3, CH bending vibration), 1116 (CN stretching vibration), 720 (–CH2–, CH bending vibration).

[0026] Example 3 This embodiment further provides another method for preparing the extractant, which is... N,N,N',N',N'',N'', N''',N''',N'''',N'''' -Decaoctyldiethylenetriaminepentaacetamide; its preparation process uses the following chemical formula:

[0027] The preparation steps are largely the same as those in Example 1, with the following differences: In step S1, 20 g of ethylenediaminetetraacetic acid was replaced with 19.67 g of diethylenetriaminepentaacetic acid (50 mmol, 1.0 eq), and 35.4 g of di-n-butylamine was replaced with 60.37 g of di-n-octylamine (250 mmol, 5.0 eq). 28.4g of triethylamine was replaced with 25.80g (255 mmol, 5.1 eq), 37.0g of 1-hydroxybenzotriazole was replaced with 33.78g (250 mmol, 5.0 eq), and 52.5g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride was replaced with 47.93g (250 mmol, 5.0 eq).

[0028] In step S3, a gradient elution is performed using a mixture of petroleum ether and ethyl acetate at a volume ratio of 3:1. The resulting extractant is denoted as extractant L. Ⅲ The yield is 44%, and its structural formula is shown in Equation V: Formula V; Please refer to Figure 5 Extractant L Ⅲ The specific structural characterization data are as follows: 1H NMR (400 MHz, CDCl3) δ 3.53 (s, 8H), 3.43 (s, 2H), 3.21 (q, 20H), 2.80 (d, 8H), 1.56 – 1.41 (m, 20H), 1.26 (s, 100H), 0.87 (m, 30H); ESI-HRMS (C 94 H 189 N8O5 + (Calculated value), m / z: 1511.4831 (1511.4810); FT-IR (KBr, ν / cm -1 ): 2924, 2852 (-CH3,-CH2, CH stretching vibration), 1642 (C=O stretching vibration), 1461, 1375 (-CH3,-CH2, CH bending vibration), 1113 (CN stretching vibration).

[0029] Verification example: As can be seen from the above, the extractant L synthesized in Examples 1-3 of this invention... Ⅰ -L Ⅲ All of these compounds belong to the amine-amide class. These compounds extract metal ions generally following a neutral complexation extraction mechanism, where the carbonyl oxygen atom and tertiary amine nitrogen atom in the compound form coordinate bonds with the metal ion, creating a stable extractable that is readily soluble in the organic phase. Therefore, they can efficiently extract metal ions from the aqueous phase to the organic phase. In light of this, this validation example verifies the effectiveness of extractant L. Ⅰ -L Ⅲ The effects of Sc on nitric acid solutions of different concentrations 3+ The specific extraction effect of the sample was demonstrated in the following experiments: 1) Extractant L Ⅰ -L Ⅲ The effect of HNO3 on Sc 3+ Extraction effect: Weigh out an appropriate amount of scandium nitrate and dissolve it in nitric acid solutions of different concentrations to prepare a 100 ppm Scandium solution. 3+ The solution was an aqueous phase, in which the concentration of nitric acid solution ranged from 0.05 to 2.0 mol / L. Then, the Sc in the aqueous phase was measured. 3+ Concentration, denoted as C ini， spare.

[0030] Weigh out an appropriate amount of extractant L Ⅰ Dissolve the extractant in 5 / 95 (v / v) n-octanol / n-dodecane as a diluent; separately weigh an appropriate amount of extractant L. Ⅱ and L ⅢEach of the three organic phases was dissolved in n-dodecane and prepared into a 0.10 mol / L solution as the organic phase, and the solutions were labeled in groups. Equal volumes of each organic phase were then pre-equilibrated three times with nitric acid of the corresponding acidity (0.05–2.0 mol / L for the aqueous phase corresponding to the metal ion concentration). After pre-equilibration, 1 mL of each aqueous and organic phase was mixed in a 10 mL ground glass joint test tube and placed in a constant temperature water bath at 25 ± 0.5 ℃ with magnetic stirring for 1.0 h. The test tubes were then centrifuged to separate the phases, and the scandium ion concentration in the aqueous phase after extraction was measured and denoted as C. eq The allocation ratio is calculated using the difference method, and the calculation method is as follows:

[0031] Experimental results are as follows Figure 1 As shown in the figure. It can be seen that the three extractants prepared in Examples 1-3 all have an effect on Sc. 3+ It has high extraction performance. Especially L II Extractant for Sc across the entire acidity study range 3+ The extraction partition ratios were all greater than 100.

[0032] It is worth mentioning that in carboxylic acid extraction systems commonly used for rare earth metal extraction, such as cycloalkanoic acids, their effect on Sc 3+ The extraction efficiency of such carboxylic acids typically decreases significantly with decreasing acidity. Literature reports that the extraction efficiency of Sc using such carboxylic acids in hydrochloric or sulfuric acid solutions is significantly reduced. 3+ Even under higher pH (2–4) conditions, the extraction efficiency is often below 80% (corresponding to partition ratio D). M <5–10) and sensitive to acidity, unable to maintain high extraction efficiency under strongly acidic conditions (Salman AD; et al. 2022). Similarly, for amine extractants (such as primary / secondary amines, quaternary ammonium salts, etc.), their mechanism of action is mainly anion exchange, and competitive protonation is severe under highly acidic conditions, leading to Sc 3+ Limited extraction capacity. In some studies, even when the pH was adjusted to weakly acidic conditions, the amine extraction system without cooperating ligand assistance showed limited extraction capacity. 3+ The extraction efficiency is typically difficult to exceed 70–85% (Zou, D; et al. 2021). This performance is particularly insufficient when dealing with industrial high-acidity nitric acid extraction systems.

[0033] Compared to the aforementioned common carboxylic acid and amine extractants, the L of this invention... II The extractant system not only targets Sc 3+ With an extraction partition ratio higher than 100, it exhibits higher extraction capacity and a wider operating window across the entire nitric acidity range, thereby significantly improving the extraction and separation efficiency of scandium.

[0034] at the same time, Figure 1 The experimental results also show that the concentration of nitric acid affects the extraction efficiency of Sc. 3+ The effects are not the same. Within the 0.05-2.0 mol / L nitric acid concentration range, the extractant L... I The partition ratio of scandium increases with increasing acidity, which can be attributed to the salting-out effect of nitric acid; extractant L II and L III The partition ratio of scandium decreases with increasing acidity, which may be due to the extractant L. II and L III The stronger alkalinity of the extractant leads to a decrease in the effective concentration of the extractant due to the extraction process itself involving nitric acid. At low acidity (<0.20 mol / L), the extraction capabilities of each extractant for scandium are ranked as follows: L II >L Ⅲ >L I At higher acidity (0.20 mol / L), the extraction capabilities of various extractants for scandium are as follows: L II >L I >L III In other words, the better the lipid solubility and the lower the alkalinity of the extractant, the stronger its ability to extract scandium. Therefore, suitable alkalinity and good lipid solubility enable the extractant to have the best extraction ability for scandium.

[0035] 2) Extractant L Ⅱ The effect of HNO3 on Sc 3+ Specific extraction effect: Weigh out an appropriate amount of nitrate and dissolve it in nitric acid solutions of different concentrations to prepare a mixed solution containing 100 ppm each of Mg, Al, Fe, Co, Ni and Sc as the aqueous phase. The concentration of the nitric acid solution ranges from 0.01 to 2.0 mol / L. Then, determine the initial concentration of each ion in the aqueous phase for later use.

[0036] Weigh out an appropriate amount of extractant L Ⅱ The organic phase was prepared by dissolving the organic phase in n-dodecane to a concentration of 0.1 mol / L. Pre-equilibration was then achieved three times by contacting the organic phase with nitric acid of the appropriate acidity (0.01–2.0 mol / L corresponding to the acidity of the aqueous phase containing metal ions). After pre-equilibration, 1 mL of each phase was taken and mixed in a 10 mL ground glass joint test tube. The mixture was then magnetically stirred in a constant temperature water bath at 25 ± 0.5 ℃ for 1.0 h. The tubes were then centrifuged to separate the phases. The concentrations of each ion in the extracted aqueous phase were measured and recorded as , and the separation factor was calculated as follows:

[0037] The experimental results are shown in Table 1 and Figure 2 As shown, SF is Sc 3+ Separation factor values ​​with other metals. It can be seen that L...II The extractant still has an effect on Sc even under conditions where impurities coexist. 3+ It exhibits excellent extraction performance within the set acidity range, D Sc Greater than 82.6. Furthermore, the extractant's extraction capacity for each metal ion follows the Sc... 3+ >Fe 3+ >Co 3+ Ni 2+ » Mg 2+ ≈Al 3+ The order, and basically no extraction of Mg. 2+ And Al 3+ .

[0038] In addition, although L II Extractant for Fe 3+ It also exhibited good extraction ability, but when the nitric acid concentration was greater than 1.0 mol / L, its ability to extract Fe was reduced. 3+ The extraction partition ratio decreased significantly (D) Fe <0.2). Therefore, L II The extractant in the range of 0.01–2.0 mol / L HNO3 can specifically extract Sc from solutions containing impurity ions. 3+ And the SF value can reach 10. 3 -10 4 The magnitude indicates that it has good extraction selectivity.

[0039] Table 1: L II Sc in 0.01-2.0 mol / L HNO3 3+ Separation factor value with other ions

[0040] Among them, under these conditions, no change in metal ion concentration was detected before and after extraction in a, and in D... M » 0.01.

[0041] In summary, the embodiments of the present invention provide an extractant for efficient separation and extraction of scandium and its preparation method. The extractant prepared by the present invention contains only four elements: C, H, O, and N, which meets the standards of environmentally friendly green extractants. It can achieve efficient extraction of scandium ions over a wide acidity range, while also having environmental protection properties and good economic value. The extractant prepared by this invention can achieve specific extraction of scandium ions among a variety of heteroions, greatly improving the extraction efficiency of scandium and better meeting the industrial demand for efficient extraction of scandium.

[0042] The embodiments described above are some, but not all, embodiments of the present invention. The detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. An extractant for the efficient separation and extraction of scandium, characterized in that, The chemical formula of the extractant is shown in Formula I and / or Formula II: Formula I; Formula II; Where R1 and R2 each represent carbon chain lengths of C4-C. 12 alkane chain.

2. A method for preparing an extractant for the efficient separation and extraction of scandium as described in claim 1, characterized in that, Includes the following steps: S1: DMF, amino polycarboxylic acid chelating agent, triethylamine and 1-hydroxybenzotriazole were mixed in proportion under ice-salt bath conditions and stirred evenly. Then, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride was added in batches for activation. Then, an aliphatic secondary amine was added, and the mixture was heated and reacted for 20-30 hours to obtain the reaction solution. S2: After the reaction solution is cooled, it is filtered, deionized water is added and extracted with ethyl acetate; then washed, dried and rotary evaporated to obtain an oily substance. S3: Add petroleum ether to the oily substance, heat and stir, cool, remove impurities and wash to obtain the extractant.

3. The preparation method according to claim 2, characterized in that, In step S1, the molar ratio of DMF, aminopolycarboxylic acid chelating agent, triethylamine, 1-hydroxybenzotriazole, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride and aliphatic secondary amine is (90-95):(0.6-0.7):(11-14):(10-13):(10-14):(10-14).

4. The preparation method according to claim 3, characterized in that, The aminopolycarboxylic acid chelating agent is any one or more of ethylenediaminetetraacetic acid, diethylenetriaminepentaacetic acid, aziridinetriacetic acid, cyclohexanediaminetetraacetic acid, or ethylene glycol diethyl ether diaminetetraacetic acid.

5. The preparation method according to claim 4, characterized in that, The aliphatic secondary amine is any one or more of di-n-butylamine, di-n-octylamine, dihexylamine, diheptylamine, or didecylamine.

6. The preparation method according to claim 2, characterized in that, In step S2, the extraction is performed 3 times and the washing is performed 3 times.

7. The preparation method according to claim 2, characterized in that, In step S3, the elution method is silica gel column chromatography separation, and gradient elution is performed using petroleum ether and ethyl acetate at a volume ratio of (2-5):1.

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