Homogeneous extraction method for metal ions based on temperature response type organic phosphoric acid derived ionic liquid

Abstract

The invention discloses a homogeneous extraction method for metal ions based on temperature response type organic phosphoric acid derivative ionic liquid, which comprises the following steps: screening and designing quaternary ammonium organic phosphoric acid derivative ionic liquid with temperature response characteristics, synthesizing the ionic liquid, and finally applying the ionic liquid to homogeneous liquid-liquid extraction of metal ions. The invention provides a metal ion homogeneous extraction method below a low critical solution temperature by utilizing the characteristic that the ionic liquid is mixed with water to present the low critical solution temperature. Compared with traditional heterogeneous extraction, the method has the advantages that a mass transfer barrier across a liquid-liquid interface is fundamentally eliminated, the inherent high viscosity problem of the ionic liquid is solved, the mass transfer efficiency is remarkably enhanced, and the extraction time efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrometallurgy, and in particular relates to a homogeneous extraction method of metal ions based on temperature-responsive organic phosphoric acid-derived ionic liquid. Background Art

[0002] Organophosphoric acid extractants are widely used in the field of hydrometallurgy to extract and recover precious metals such as copper, nickel, cobalt, and rare earth elements from different sources such as ores, industrial processing residues, and electronic waste. Among them, the more widely used commercial ones include P204 (di(2-ethylhexyl) phosphate), P507 (mono(2-ethylhexyl)-2-ethylhexyl phosphonate), and Cyanex272 (di(2,4,4-trimethylpentyl)phosphinic acid). Ionic liquids are salts that melt at room temperature and have significant chemical and thermal stability, non-flammability, and low volatility. Replacing the protons of organophosphoric acid and developing corresponding ionic liquid derivatives can combine the advantages of organophosphoric acid as an extractant with the inherent excellent physical and chemical properties of ionic liquids, destroy the original dimer structure and avoid proton exchange during the extraction process, thereby improving the extraction performance and having good industrial application prospects. Currently, the more successful commercial applications of this type of ionic liquid include Cyphos IL 104 (trihexyl (tetradecyl) phosphine bicyclo (2,4,4-trimethylpentyl) phosphine).

[0003] However, in actual liquid-liquid extraction applications, organophosphoric acid-derived ionic liquids are often affected by high viscosity and are accompanied by low mass transfer efficiency. The traditional solution is to add diluents, such as kerosene or other organic solvents such as toluene, to reduce viscosity, but this will introduce volatile organic solvents and increase the complexity of the composition regulation of the extractant. As an effective alternative solution, homogeneous liquid-liquid extraction technology has attracted much attention in recent years (public document "Homogeneous liquid-liquid extraction of metal ions with a functionalized ionic liquid"). The realization of homogeneous liquid-liquid extraction depends on a reversible phase change system with temperature responsiveness. The system is usually composed of two solvents, which are characterized by a high critical solution temperature (UCST, upper critical solution temperature) or a low critical solution temperature (LCST, lower critical solution temperature). The UCST system is soluble at high temperature and phase separated at low temperature, while the LCST system is the opposite. Therefore, by regulating the temperature, the heterogeneous mixture can be converted into a homogeneous mixture, thereby effectively solving the mass transfer resistance problem caused by heterogeneous extraction and high viscosity, shortening the extraction time and improving efficiency. Summary of the invention

[0004] In view of the problem that the existing organophosphate-derived ionic liquids have high mass transfer resistance in heterogeneous extraction, the present invention aims to provide a homogeneous extraction method for metal ions based on temperature-responsive organophosphate-derived ionic liquids.

[0005] The specific technical solutions are as follows:

[0006] A method for homogeneous extraction of metal ions based on temperature-responsive organophosphoric acid-derived ionic liquids comprises the following steps:

[0007] 1) Screening of temperature-responsive organophosphate-derived ionic liquids: Ionic liquids can be mixed with water to form an LCST system, and the cation of the ionic liquid is a quaternary ammonium ion [R1R2R3R4N] + The anion is a deprotonated organic phosphate, and the logP calculation is performed using the COSMO model and β1<αlogP 阳离子 +logP 阴离子 <β2 is a linear constraint condition. Under the premise of a given organic phosphate anion, for a quaternary ammonium cation [R1R2R3R4N] + The types are screened to ensure that the ionic liquid contains both hydrophilic and hydrophobic ions, and both cannot be hydrophilic or hydrophobic at the same time, wherein R1, R2, R3 and R4 are each independently selected from alkyl, alkoxy or aryl, α represents the weight coefficient, β1 represents the lower bound of the sum of the two terms, β2 represents the upper bound of the sum of the two terms, logP represents the octanol / water partition coefficient predicted based on the model, the larger the logP, the more hydrophobic, and the smaller the logP, the more hydrophilic. Considering the systematic error associated with the model calculation, the selection of its specific value depends on the logP calculation model;

[0008] 2) Synthesis of temperature-responsive organophosphoric acid-derived ionic liquid: sodium and ethanol are reacted to prepare sodium alcoholate, the sodium alcoholate is added dropwise to an ethanol solution containing quaternary ammonium chloride, the mixture is stirred for reaction, and then centrifuged to remove the precipitated sodium chloride, the supernatant is taken out, water of an equal volume to the supernatant is added, and stirred and mixed, a hydrolysis reaction occurs to generate a quaternary ammonium base and ethanol, organophosphoric acid is further added to the hydrolysis product, and an acid-base neutralization reaction occurs with the quaternary ammonium base under heating reflux conditions to obtain the target ionic liquid, after cooling to room temperature, dichloromethane is added for extraction, the organic phase and the aqueous phase are separated in a separatory funnel, and the The separated organic phase is heated to remove dichloromethane, water and ethanol to obtain a product. The product is characterized by a transparent or light yellow viscous liquid, is hygroscopic, and needs to be sealed for storage; 3) Homogeneous extraction of metal ions by organophosphoric acid-derived ionic liquid: The quaternary ammonium organophosphoric acid-derived ionic liquid synthesized in step 2) is used as an extractant and mixed with a neutral or acidic aqueous phase containing metal ions. During the mixing process, the temperature needs to be controlled below the lower critical solution temperature of the system, stirred for equilibrium, and heated to above the corresponding lower critical solution temperature of the system. The solution is phase-separated to complete the extraction.

[0009] Furthermore, the COSMO model in step 1) is a COSMO-RS, COSMO-SAC-2010 or COSMO-SAC-dsp model, and the linear constraints include β1=3, α=-0.8824, and β2=7.5.

[0010] Furthermore, in step 2), the molar ratio of sodium alkoxide to quaternary ammonium chloride is 1:1.

[0011] Furthermore, in step 2), after sodium alcoholate is added dropwise to the ethanol solution containing quaternary ammonium chloride, the reaction temperature is 313-333K, the time is 3-5h, and the reaction is centrifuged at a speed of 5000-8000rpm for 4-10min in a centrifuge to remove the precipitated sodium chloride.

[0012] Furthermore, in step 2), the molar ratio of the organic phosphoric acid to the quaternary ammonium base is 1.05-1.1:1.

[0013] Furthermore, in step 2), the mixture is heated to reflux for reaction by vigorously stirring the mixture under reflux conditions at 323-333 K for 9-12 hours. During the extraction process, the volume ratio of the added dichloromethane to the mixed solution is 0.8:1 to 1.5:1.

[0014] Furthermore, in step 3), the homogeneous extraction equilibrium time is 3-10 min, and preferably, the ionic liquid is [N 4444][Cyanex272], that is, the cation is tetrabutyl quaternary ammonium ion and the anion is deprotonated organic phosphate Cyanex272, the volume ratio of ionic liquid to water phase is 1:1, the extraction temperature is between 283K-298K, the total molar number of metal ions is <0.5mol / L, and the temperature is raised to 333-343K for phase separation after the extraction.

[0015] The beneficial effects of the present invention are:

[0016] The present invention proposes to use a temperature-responsive organophosphoric acid-derived ionic liquid that forms an LCST system with water to achieve low-temperature homogeneous extraction and high-temperature automatic phase separation, thereby breaking the mass transfer barrier of the extraction process and improving the extraction time efficiency. Furthermore, a matching design and synthesis scheme are provided for the development of the above-mentioned new ionic liquid. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the homogeneous extraction method of metal ions based on temperature-responsive organophosphate-derived ionic liquids;

[0018] Figure 2 For [N 4444 [Cyanex272] 1 H and 13 C NMR spectrum;

[0019] Figure 3 For [N 111,14 [Cyanex272] 1 H and 13 C NMR spectrum;

[0020] Figure 4 For [N 3333 [P507] 1 H and 13 C NMR spectrum;

[0021] Figure 5 For [N 4444 [P507] 1 H and 13 C NMR spectrum;

[0022] Figure 6 For [N 111,14 [P507] 1 H and 13 C NMR spectrum;

[0023] Figure 7 It is the cloud point temperature diagram of different ionic liquid-water systems;

[0024] Figure 8 For [N 4444[Cyanex272] extraction efficiency of three alkali metal ions;

[0025] Fig. 9 For Li + A graph showing how allocation ratios change over time. DETAILED DESCRIPTION

[0026] The present invention is further described below in conjunction with the accompanying drawings and embodiments, but the protection scope of the present invention is not limited thereto.

[0027] like Figure 1 As shown, it is a schematic diagram of a homogeneous extraction method of metal ions based on a temperature-responsive organophosphate-derived ionic liquid. Example 1 shows several novel organophosphate-derived ionic liquids that can form an LCST system with water, which are developed using the design and synthesis scheme provided in this application. Example 2 shows the liquid-liquid homogeneous extraction effect of different alkali metal ions, using an ionic liquid developed in Example 1 as a representative.

[0028] Example 1: Design and synthesis of thermosensitive organophosphate-derived ionic liquids

[0029] Screening of temperature-responsive organophosphate-derived ionic liquids: Anions selected as [P507] - and [Cyanex272] - The cation database contains 70 tetraalkyl-substituted quaternary ammonium cations with different carbon chain lengths. The logP calculation was performed using the COSMO-RS model and 3<-0.8824logP was applied. 阳离子 +logP 阴离子 <7.5 as the condition for screening, and several candidate quaternary ammonium cations shown in Table 1 were obtained.

[0030] Table 1 Screened cations and their corresponding chloride precursors

[0031] serial number Reagent name CAS Number cation log P 1 Tetramethylammonium chloride 75-57-0 <![CDATA[[N 1111 ] + ]]> 1.1994 2 Trimethyl Ethyl Ammonium Chloride - <![CDATA[[N 2111 ] + ]]> 1.7458 3 Methyltriethylammonium chloride 10052-47-8 <![CDATA[[N 2221 ] + ]]> 2.8203 4 Dimethylethylpropylammonium chloride - <![CDATA[[N 3211 ] + ]]> 2.8925 5 Trimethylbutylammonium chloride 4574-04-3 <![CDATA[[N 4111 ] + ]]> 2.9033 6 Tetraethylammonium chloride 56-34-8 <![CDATA[[N 2222 ] + ]]> 3.2476 7 Trimethylhexyl ammonium chloride - <![CDATA[[N 6111 ] + ]]> 3.9808 8 Trimethylheptyl ammonium chloride - <![CDATA[[N 7111 ] + ]]> 4.5339 9 Trimethyloctyl ammonium chloride 10108-86-8 <![CDATA[[N 8111 ] + ]]> 5.0708 10 Triethylhexyl ammonium chloride - <![CDATA[[N 6222 ] + ]]> 5.4505 11 Tetrapropylammonium chloride 5810-42-4 <![CDATA[[N 3333 ] + ]]> 5.6856 12 Triethylheptane ammonium chloride - <![CDATA[[N 7222 ] + ]]> 6.0122 13 Trimethyldecyl ammonium chloride 10108-87-9 <![CDATA[[N 111,10 ] + ]]> 6.1476 14 Methyltributylammonium chloride 56375-79-2 <![CDATA[[N 4441 ] + ]]> 6.3142 15 Triethyloctyl ammonium chloride - <![CDATA[[N 8222 ] + ]]> 6.5656 16 Tetrabutylammonium chloride 1112-67-0 <![CDATA[[N 4444 ] + ]]> 7.9653 17 Trimethyltetradecylammonium chloride 976753 <![CDATA[[N 111,14 ] + ]]> 8.2818

[0032] Synthesis of temperature-responsive organophosphoric acid-derived ionic liquids: Considering the purchase feasibility and economy, five anion and cation combinations were selected for the synthesis of ionic liquids: [N 4444 ][Cyanex272],[N 111,14 ][Cyanex272],[N 3333 ][P507],[N 4444 ][P507],[N 111,14][P507]. In the following description of the synthesis method, [R1R2R3R4N] is used to represent a cation, and [A] is used to represent an anion. The specific steps are as follows: 13.9 mmol of sodium is reacted with 25 mL of ethanol for 3 h to prepare a sodium alcoholate (EtONa) solution, and the sodium alcoholate solution is added dropwise to an ethanol solution containing an equal mole (13.9 mmol) of [R1R2R3R4N]Cl. The solution is stirred at 323 K for 4 h, and then placed in a centrifuge and centrifuged at 8000 rpm for 10 min to remove the precipitated sodium chloride, and the supernatant is poured out, and an equal volume of water is added and mixed for 0.5 h.

[0033] [R1R2R3R4N][OH] was obtained during the hydrolysis of [R1R2R3R4N][EtO]. Organic phosphoric acid HA was added at a molar ratio of 1:1.1 to neutralize [R1R2R3R4N][OH]. The mixture was vigorously stirred at reflux for 12 h at 323 K. After cooling to room temperature, an equal volume of dichloromethane was added to extract [R1R2R3R4N][A] from the solution. The organic phase and the aqueous phase were separated in a separatory funnel, and the separated organic phase was heated to remove dichloromethane, residual water and ethanol to obtain the purified target ionic liquid [R1R2R3R4N][A].

[0034] Characterization of temperature-responsive organophosphoric acid-derived ionic liquids: The NMR spectrum can effectively reflect that the synthesized ionic liquid is the target product, and the absence of impurity peaks can also qualitatively indicate that the product has good purity.

[0035] [N 4444 The characterization results of ][Cyanex272] are as follows Figure 2 As shown: 1 H NMR (400MHz, CDCl3, δ / ppm): 3.29 / 3.16 (m, 8H), 1.85 (s, 2H), 1.59 / 1.46 (m, 8H), 1.38 (d, J = 16.1Hz, 2H), 1.30 (q,J=7.4Hz,8H),1.18(d,J=13.7Hz,4H),1.05 / 0.93(m,8H),0.85(t,J=7.3Hz,12H),0.75(d,J=1.0Hz,18H). 13 C NMR(75MHz, CDCl3, δ / ppm):58.61(4CH2),54.07 / 53.90(2CH2),31.75(2CH2),31.07(2C H),30.17(6CH3),24.00(4CH2),22.91(2CH3),22.17(2CH),19.62(4CH2),13.61(4CH3).

[0036] [N 111,14 The characterization results of ][Cyanex272] are as follows Figure 3 As shown: 1 H NMR (400MHz, CDCl3, δ / ppm): 3.36 (s, 2H), 3.30 / 3.10 (m, 9H), 1.76 (s, 2H), 1.50 (s, 2H), 1.40 / 1.27 (m, 2 H),1.16(s,6H),1.06(dd,J=11.6,4.6Hz,20H),0.91(dq,J=10.3,3.6,3.2Hz,8H),0.80 / 0.57(m,21H). 13 C NMR (75MHz, CDCl3, δ / ppm): 66.34(CH2), 53.82(2CH2), 52.97(3CH3), 322.39(CH2), 31.72(2CH2), 31.04(2C), 30.18(6CH3), 29 .44(3CH2),29.30 / 29.24(2CH2),29.15(3CH2),26.14(CH2),25.60(CH2),24.25(CH2),23.03(CH3),22.48(2CH3),13.96(2CH).

[0037] [N 3333 The characterization results of ][P507] are as follows Figure 4 As shown: 1 H NMR (400MHz, CDCl3, δ / ppm): 3.01 (s, 2H), 2.87 / 2.57 (m, 8H), 1.19 / 1.05 (m, 9H), 0.95 / 0.83 (m,2H),0.82 / 0.74(m,4H),0.66 / 0.51(m,12H),0.39(d,J=6.9Hz,12H),0.24 / 0.10(m,13H). 13 C NMR (75MHz, CDCl3, δ / ppm): 65.34(CH2), 59.91(4CH2), 40.10(CH), 33.16(CH2), 29.62(2CH2), 28.53(CH2), 2 8.14(2CH2),26.09(CH),22.84(CH2),22.58(2CH2),15.20(4CH2),13.67(2CH3),10.32(4CH3),9.86(2CH3).

[0038] [N 4444 The characterization results of ][P507] are as follows Figure 5 As shown: 1H NMR (400MHz, CDCl3, δ / ppm): 3.41 (dd, J=15.0, 6.1Hz, 2H), 3.21 / 3.11 (m, 8H), 1.60 / 1.36 (m, 10H) ,1.23(dt,J=14.8,7.1Hz,14H),1.10 / 0.91(m,12H),0.77(t,J=7.4Hz,12H),0.68 / 0.55(m,12H). 13 C NMR (75MHz, CDCl3, δ / ppm): 65.61 (CH2), 58.52 (4CH2), 40.21 (CH), 34.26 (CH2), 31.67 (CH2), 30.34 (CH2), 29.85 (2CH2), 2 8.81(CH2),28.38(CH),23.84(4CH2),23.07(CH2),22.88(2CH2),19.50(4CH2),13.86(2CH3),13.45(4CH3),10.72(2CH3).

[0039] [N 111,14 The characterization results of ][P507] are as follows Figure 6 As shown: 1 H NMR (400MHz, CDCl3, δ / ppm): 3.65 / 3.54 (m, J=5.1Hz, 2H), 3.40 (dt, J=12.3, 4.0Hz, 2H), 3.36 / 3.25 ( m,9H),1.66(s,3H),1.52 / 1.42(m,2H),1.41 / 1.31(m,5H),1.30 / 1.06(m,34H),0.88 / 0.72(m,15H). 13 C NMR (75MHz, CDCl3, δ / ppm): 66.77(CH2), 66.23(CH2), 53.16(3CH3), 40.68(CH), 34.98(CH2), 31.94(CH2), 30.87(CH2), 29.66(6CH2), 29. 44(2CH2),29.34(2CH2),29.13(CH2),28.77(2CH2),26.33(CH2,CH),23.43(CH2),23.24(2CH2),22.71(CH2),14.14(3CH3),10.48(2CH3).

[0040] The cloud point temperature refers to the temperature at which the turbidity of a mixture suddenly increases. This phenomenon usually indicates that a transition from a homogeneous phase to a heterogeneous phase has occurred at this temperature. By measuring the cloud point temperatures under different compositions, a cloud point line can be drawn. The specific measurement process of the cloud point line in this embodiment is: ionic liquids and water of different mass ratios are mixed at low temperature, placed in a circulating water bath with magnetic stirring and slowly heated at a heating rate of 1K / min, and the temperature corresponding to the homogeneous mixture just becoming turbid is recorded. Each data point is measured three times and the average value is taken. The cloud point line drawing results of different ionic liquids are shown in the figure. Figure 7 As shown, it can be reflected that the synthesized ionic liquid can show LCST behavior after mixing with water. In particular, [N 3333 ][P507] also shows UCST behavior. Different ionic liquids have different lower critical solution temperatures, [N 3333 ][P507],[N 4444 ][P507],[N 4444 The lower critical solution temperatures of the binary systems of ][Cyanex272] and water are 352K, 309K and 324K, respectively, while [N 111,14 ][P507] and [N 111,14 The lower critical solution temperature of [Cyanex272] is below 273 K and cannot be measured. The cloud point measurement results show that the screening and synthesis scheme adopted can obtain LCST-type ionic liquids, which is feasible in implementation.

[0041] Example 2: [N 4444 [Cyanex272] Homogeneous extraction of alkali metal ions

[0042] 1) Preparation of aqueous phase: Dissolve LiCl, NaCl and KCl in deionized water, and control the concentration of the three salts at 0.5 g / L respectively;

[0043] 2) Homogeneous extraction: 2 ml of the prepared aqueous phase and 2 ml of pure extractant [N 4444 [Cyanex272] was mixed at 293K, at which time the solution was homogeneous. After stirring for 30 minutes, it was placed in a constant temperature circulating water bath at 333K for 10 minutes. At this time, the solution was completely separated and the extraction was completed.

[0044] 3) Results characterization

[0045] a) Extraction thermodynamics: The extraction rate is described by the distribution ratio D, which is defined as D = (C0-C1) / C1, where: C0 is the concentration of the target metal ion in the aqueous phase before extraction, and C1 is the concentration of the target metal ion in the aqueous phase after extraction, measured by ICP-OES ion chromatograph, such as Figure 8 As shown, compared with [N 4444[Cyanex272] The distribution ratio of different alkali metal ions when reaching the extraction equilibrium state is obviously different from that of Na + and K + In comparison, [N 4444 [Cyanex272] showed a strong affinity for Li + Therefore, as a potential application, [N 4444 [Cyanex272] can be used for selective extraction of lithium, mainly in the form of Li + with Na + , K + separation.

[0046] b) Extraction kinetics: Fig. 9 The functional relationship between the distribution ratio D of lithium ions and the extraction time is provided. The results show that [N 4444 [Cyanex272] can reach extraction equilibrium in just 3 minutes, which is also attributed to the fact that homogeneous liquid-liquid extraction is conducive to the full contact between metal ions and the extractant, thereby greatly enhancing the time efficiency of the extraction.

Claims

1. A method for homogeneous extraction of metal ions based on temperature-responsive organophosphoric acid-derived ionic liquids, characterized in that: The steps include: 1) Screening of temperature-responsive organophosphate-derived ionic liquids: Ionic liquids can be mixed with water to form an LCST system, and the cation of the ionic liquid is a quaternary ammonium ion [R1R2R3R4N] + The anion is a deprotonated organic phosphate, and the logP calculation is performed using the COSMO model and β1<αlogP 阳离子 +logP 阴离子 <β2 is a linear constraint condition. Under the premise of a given organic phosphate anion, for a quaternary ammonium cation [R1R2R3R4N] + The types are screened to ensure that the ionic liquid contains both hydrophilic and hydrophobic ions, wherein R1, R2, R3 and R4 are each independently selected from alkyl, alkoxy or aryl, α represents a weight coefficient, β1 represents a lower bound of the sum of the two terms, β2 represents an upper bound of the sum of the two terms, and logP represents an octanol / water partition coefficient predicted by the model; 2) Synthesis of temperature-responsive organophosphoric acid-derived ionic liquid: sodium and ethanol are reacted to prepare sodium alcoholate, the sodium alcoholate is added dropwise to an ethanol solution containing quaternary ammonium chloride, the mixture is stirred for reaction, and then centrifuged to remove precipitated sodium chloride, the supernatant is taken out, water of an equal volume to the supernatant is added and stirred to cause a hydrolysis reaction to generate a quaternary ammonium base and ethanol, organophosphoric acid is further added to the hydrolyzate, and the target ionic liquid is obtained by an acid-base neutralization reaction with the quaternary ammonium base under heating and reflux conditions, and after cooling to room temperature, dichloromethane is added for extraction, and an organic phase and an aqueous phase are separated in a separatory funnel, and the separated organic phase is heated to remove dichloromethane, water and ethanol to obtain a product; 3) Homogeneous extraction of metal ions by organophosphate-derived ionic liquid: The quaternary ammonium organophosphate-derived ionic liquid synthesized in step 2) is used as an extractant and mixed with a neutral or acidic aqueous phase containing metal ions. During the mixing process, the temperature needs to be controlled below the lower critical solution temperature of the system, stirred for equilibrium, and the temperature is raised to above the corresponding lower critical solution temperature of the system, and the solution is separated to complete the extraction.

2. A method for homogeneous extraction of metal ions based on temperature-responsive organophosphoric acid-derived ionic liquids according to claim 1, characterized in that: The COSMO model in step 1) is the COSMO-RS, COSMO-SAC-2010 or COSMO-SAC-dsp model, and the linear constraints include β1=3, α=-0.8824, and β2=7.

5.

3. A method for homogeneous extraction of metal ions based on temperature-responsive organophosphoric acid-derived ionic liquids according to claim 1, characterized in that: In step 2), the molar ratio of sodium alkoxide to quaternary ammonium chloride is 1:

1.

4. A method for homogeneous extraction of metal ions based on temperature-responsive organophosphoric acid-derived ionic liquids according to claim 1, characterized in that: In step 2), sodium alcoholate is added dropwise to the ethanol solution containing quaternary ammonium chloride, the reaction temperature is 313-333K, the time is 3-5h, and the reaction is centrifuged at 5000-8000rpm for 4-10min to remove the precipitated sodium chloride.

5. The method for homogeneous extraction of metal ions based on temperature-responsive organophosphoric acid-derived ionic liquid according to claim 1, characterized in that: The molar ratio of the organic phosphoric acid to the quaternary ammonium base in step 2) is 1.05-1.1:

1.

6. A method for homogeneous extraction of metal ions based on temperature-responsive organophosphoric acid-derived ionic liquids according to claim 1, characterized in that: In step 2), the mixture is heated to reflux for reaction by vigorously stirring the mixture under reflux conditions at 323-333 K for 9-12 hours. During the extraction process, the volume ratio of the added dichloromethane to the mixed solution is 0.8:1 to 1.5:

1.

7. A method for homogeneous extraction of metal ions based on temperature-responsive organophosphoric acid-derived ionic liquids according to claim 1, characterized in that: Step 3) The homogeneous extraction equilibrium time is 3-10 min.

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