Ionic liquid, preparation method and application thereof, and method for extracting gold (III) and / or palladium (II)

Abstract

The invention belongs to the technical field of precious metal separation, and particularly relates to ionic liquid, a preparation method and application thereof and a method for extracting gold (III) and / or palladium (II). The structural formula of the ionic liquid is as shown in the formula 1, and the ionic liquid is difunctional thiomorpholine ionic liquid, is low in cost, simple in structure and high in stability, and has good biodegradability, low toxicity and high recoverability. At room temperature, the ionic liquid and water are two phases which are immiscible, gold (III) and palladium (II) can be efficiently extracted, the extraction efficiency is high, the balance time is short, and the problems that mass transfer in the extraction process is blocked and depends on an organic solvent due to the fact that the viscosity of the ionic liquid is large are solved. Functional atom sulfur is introduced to a cation framework of the ionic liquid, so that the ionic liquid not only has an ion exchange function on gold (III) and palladium (II), but also has a coordination function, and shows excellent selectivity and reusability on the gold (III) and the palladium (II). # imgabs0 #

Description

Technical Field

[0001] The invention belongs to the technical field of precious metal separation, and in particular relates to an ionic liquid and a preparation method and application thereof, and a method for extracting gold (III) and / or palladium (II). Background Art

[0002] Gold and palladium have many excellent properties that cannot be replaced by other metals. With the continuous development of science and technology, gold and palladium are widely used in aerospace, biomedicine, catalysis and other fields. Gold and palladium are scarce in the earth's crust. Compared with mining and metallurgy, the recovery of gold and palladium from complex secondary resources (such as waste plastic waste, scrapped electronic and electrical equipment, and waste catalysts, etc.) is less difficult and less costly, with less waste emissions, and has important economic and environmental significance.

[0003] Liquid-liquid extraction is the main method for industrial refining of precious metals, with advantages such as simple process, fast reaction rate, good separation effect and low energy consumption. However, traditional extractants often add flammable, volatile or highly toxic organic solvents as diluents when used, resulting in a harsh production environment and a high risk factor. Therefore, it is of great significance to find a green, sustainable and highly selective extractant for the recovery of gold and palladium from secondary resources.

[0004] Ionic liquids are considered to be an effective alternative to traditional extractants. They are composed of anions and cations and have the characteristics of high stability, low volatility and non-flammability. Existing ionic liquids, such as imidazole-based, quaternary ammonium-based, and pyridinium-based ionic liquids, show excellent extraction performance for gold and palladium. However, existing ionic liquids have high viscosity, and mass transfer is hindered during the extraction process. Organic solvents must be used as diluents, and there is still a drawback of relying on organic solvents, which affects their "green and environmentally friendly" characteristics. Summary of the invention

[0005] In view of this, the object of the present invention is to provide an ionic liquid and a preparation method and application thereof, and a method for extracting gold (III) and / or palladium (II). The ionic liquid provided by the present invention has a low viscosity, which solves the problem that the mass transfer in the extraction process is blocked due to the high viscosity of the ionic liquid and the reliance on organic solvents, and the extraction of gold and palladium can be achieved without using an organic solvent.

[0006] The present invention provides an ionic liquid, the structural formula of which is shown in Formula 1:

[0007]

[0008] In Formula 1, n=5, 7 or 9.

[0009] The present invention also provides a method for preparing the ionic liquid described in the above technical solution, comprising the following steps:

[0010] Mixing thiomorpholine, halogenated alkane and acetonitrile for quaternization reaction, removing acetonitrile, and obtaining an intermediate; the halogenated alkane includes halogenated hexane, halogenated octane or halogenated decane;

[0011] The intermediate is dissolved in an organic solvent, and mixed with an aqueous solution of bistrifluoromethylsulfonyl imide salt to carry out anion exchange reaction to obtain an ionic liquid.

[0012] Preferably, the molar ratio of the thiomorpholine to the halogenated alkane is 1:2 to 1:2.5.

[0013] Preferably, the temperature of the quaternization reaction is 70-80° C. and the time is 36-48 hours.

[0014] Preferably, the molar ratio of the intermediate to the bis(trifluoromethylsulfonyl)imide salt is 1:1 to 1:1.5.

[0015] Preferably, the anion exchange reaction is carried out at room temperature and for 6 to 12 hours.

[0016] The present invention also provides the use of the ionic liquid described in the above technical solution or the ionic liquid obtained by the above preparation method in the extraction of gold (III) and / or palladium (II).

[0017] The present invention also provides a method for extracting gold (III) and / or palladium (II), comprising the following steps:

[0018] The ionic liquid and the aqueous phase containing gold (III) and / or palladium (II) are mixed and shaken for extraction, and the layers are separated to obtain a lower layer of the ionic liquid containing gold (III) and / or palladium (II) and an upper layer of the raffinate aqueous phase;

[0019] The ionic liquid is the ionic liquid described in the above technical solution or the ionic liquid obtained by the above preparation method.

[0020] Preferably, the solvent of the aqueous phase containing gold (III) and / or palladium (II) is a hydrochloric acid solution, and the concentration of HCl in the hydrochloric acid solution is 0.1 to 4 mol / L.

[0021] Preferably, the dosage ratio of the ionic liquid to the aqueous phase containing gold (III) and / or palladium (II) is 0.01-0.1 mmol:5 mL, and the total concentration of gold (III) and palladium (II) in the aqueous phase containing gold (III) and / or palladium (II) is 0.5-30 mmol / L.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The present invention provides an ionic liquid, the structural formula of which is shown in Formula 1:

[0024]

[0025] In Formula 1, n=5, 7 or 9.

[0026] The present invention creatively replaces the oxygen atoms in the traditional morpholine ionic liquid with sulfur atoms which are also electronegative, and transforms it into a bifunctional liquid; selects NTf2 - (Bistrifluoromethylsulfonyl imide ion) as the anion of the ionic liquid, the ionic liquid has the excellent properties of low viscosity, high hydrophobicity and strong stability. In the process of extracting gold (III) and palladium (II), there is no need to add additional volatile organic solvents as diluents, which is more green and safe, and solves the problem of mass transfer obstruction in the extraction process due to the high viscosity of the ionic liquid and dependence on organic solvents. At the same time, thanks to the introduction of the functional atomic sulfur, the ionic liquid has not only ion exchange function but also coordination function for gold (III) and palladium (II), breaking the traditional single extraction mechanism and improving the extraction capacity and selectivity. The ionic liquid described in the present invention has extremely high extraction efficiency and extraction selectivity for gold (III) and palladium (II), and the extraction efficiency of gold (III) and palladium (II) can reach 97% and 100% respectively, while the extraction rate of other base metals is less than 5%.

[0027] The present invention also provides a method for preparing the ionic liquid described in the above technical solution. The preparation method is simple, highly practical and easy to promote. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 : is the hydrogen nuclear magnetic resonance spectrum of the bifunctional thiomorpholine ionic liquid in the embodiment, the abscissa is the chemical shift, from bottom to top are [diHTP][Tf2N], [diOTP][Tf2N] and [diDTP][Tf2N];

[0030] Figure 2 The effect of the initial metal concentration on the ability of the ionic liquid to extract gold (III) and palladium (II) in Examples 1 to 3, the abscissa is the initial metal concentration, and the ordinate is the maximum extraction capacity of gold (III) and palladium (II);

[0031] Figure 3The effect of ionic liquids on the extraction rate of gold (III) and palladium (II) in the simulated multi-metal solution at different hydrochloric acid concentrations in Example 1, the X-axis coordinate is the metal type, the Y-axis coordinate is the hydrochloric acid concentration, and the Z-axis coordinate is the extraction rate;

[0032] Figure 4 The results of the repeated use test of ionic liquid for extracting gold (III) and palladium (II) in Example 1 are shown; the abscissa is the number of cycles, and the ordinate is the extraction rate. DETAILED DESCRIPTION

[0033] The present invention provides an ionic liquid, the structural formula of which is shown in Formula 1:

[0034]

[0035] In Formula 1, n=5, 7 or 9.

[0036] The ionic liquid described in the present invention is a bifunctional ionic liquid, which is a sulfur-functionalized thiomorpholine ionic liquid. The present invention creatively replaces the oxygen atom in the traditional morpholine ionic liquid with a sulfur atom which is also electronegative, and transforms it into a bifunctional ionic liquid. Thanks to the introduction of the functional atom sulfur, the ionic liquid has not only an ion exchange function but also a coordination function for gold (III) and palladium (II). AuCl4 - and PdCl4 2- It will preferentially react with N in the ionic liquid + Ion exchange is achieved by combining electrostatic attraction. When the anion is completely exchanged, it forms a stable extractant by coordinating with the functional sulfur atom on the cation skeleton. The introduction of sulfur atoms can improve the extraction capacity and selectivity of ionic liquids for gold (III) and palladium (II). - As the anion of ionic liquids, they can give ionic liquids excellent properties such as low viscosity, high hydrophobicity and strong stability.

[0037] In the present invention, when n=5, 7 or 9, the ionic liquids are named [diHTP][Tf2N], [diOTP][Tf2N], [diDTP][Tf2N], respectively.

[0038] The present invention also provides a method for preparing the ionic liquid described in the above technical solution, comprising the following steps:

[0039] Mixing thiomorpholine, halogenated alkane and acetonitrile for quaternization reaction, removing acetonitrile, and obtaining an intermediate; the halogenated alkane includes halogenated hexane, halogenated octane or halogenated decane;

[0040] The intermediate is dissolved in an organic solvent, and mixed with an aqueous solution of bistrifluoromethylsulfonyl imide salt to carry out anion exchange reaction to obtain an ionic liquid.

[0041] In the present invention, unless otherwise specified, the materials and equipment used are commercially available products in the art.

[0042] The invention comprises mixing thiomorpholine, halogenated alkane and acetonitrile for quaternary amination reaction, removing acetonitrile and obtaining an intermediate; the halogenated alkane comprises halogenated hexane, halogenated octane or halogenated decane.

[0043] In the present invention, the molar ratio of the thiomorpholine to the halogenated alkane is preferably 1:2 to 1:2.5, more preferably 1:2.1.

[0044] In the present invention, the halogenated alkane is preferably a brominated alkane, and the brominated alkane preferably includes hexyl bromide, octane bromide or decane bromide.

[0045] In the present invention, the usage ratio of thiomorpholine to acetonitrile is preferably 60mmol:100mL.

[0046] In the present invention, the quaternization reaction is preferably carried out under reflux, the temperature of the quaternization reaction is preferably 70-80° C., more preferably 75° C., and the time is preferably 36-48 h, more preferably 48 h.

[0047] In the present invention, the quaternization reaction preferably further comprises cooling, the temperature after cooling is preferably room temperature, and solid is precipitated after cooling; the method of removing acetonitrile is preferably rotary evaporation; after removing acetonitrile, the solid obtained is preferably washed, the washing reagent is preferably petroleum ether, the number of washings is preferably 3 times, and preferably washing is performed until the petroleum ether phase is colorless.

[0048] When the halogenated alkane is preferably a brominated alkane, the structural formula of the intermediate (N-dialkylthiomorpholine bromide) is as shown in Formula 2:

[0049]

[0050] The present invention dissolves the intermediate in an organic solvent, mixes the organic solvent with an aqueous solution of bis(trifluoromethylsulfonyl)imide salt, and performs anion exchange reaction to obtain an ionic liquid.

[0051] In the present invention, the organic solvent preferably includes dichloromethane or chloroform, more preferably dichloromethane. After the quaternization reaction, the acetonitrile is removed and the intermediate is dissolved in an organic solvent (such as dichloromethane), which is conducive to the separation of the product.

[0052] In the present invention, the bis(trifluoromethylsulfonyl)imide salt preferably includes lithium bis(trifluoromethylsulfonyl)imide (LiTf2N) or sodium bis(trifluoromethylsulfonyl)imide.

[0053] In the present invention, the molar ratio of the intermediate to the bis(trifluoromethylsulfonyl)imide salt is preferably 1:1 to 1:1.5, more preferably 1:1.1 to 1:1.5. The molar ratio of the present invention can make the reaction more complete.

[0054] In the present invention, the anion exchange reaction is preferably carried out at room temperature, and the time of the anion exchange reaction is preferably 6 to 12 hours, more preferably 12 hours.

[0055] In the present invention, after the anion exchange reaction, the process preferably further comprises: removing the aqueous phase, washing the organic phase, removing the organic phase again, and drying to obtain an ionic liquid. The aqueous phase is the upper layer of the system obtained by the anion exchange; the reagent for washing the organic phase is preferably deionized water, and the washing is preferably performed until no halogen ions are detected in the washing liquid; the drying temperature is preferably 60 to 80°C, more preferably 75°C, and the drying time is preferably 36 to 48 hours, more preferably 48 hours.

[0056] The present invention also provides the use of the ionic liquid described in the above technical solution or the ionic liquid obtained by the above preparation method in the extraction of gold (III) and / or palladium (II).

[0057] The present invention also provides a method for extracting gold (III) and / or palladium (II), comprising the following steps:

[0058] The ionic liquid and the aqueous phase containing gold (III) and / or palladium (II) are mixed and shaken for extraction, and the layers are separated to obtain a lower layer of the ionic liquid containing gold (III) and / or palladium (II) and an upper layer of the raffinate aqueous phase;

[0059] The ionic liquid is the ionic liquid described in the above technical solution or the ionic liquid obtained by the above preparation method.

[0060] In the present invention, the solvent of the aqueous phase containing gold (III) and / or palladium (II) is preferably a hydrochloric acid solution, and the concentration of HCl in the hydrochloric acid solution is preferably 0.1 to 4 mol / L. In a specific embodiment, the concentration of HCl in the hydrochloric acid solution can be 0.1, 1 or 2 mol / L.

[0061] In the present invention, the dosage ratio of the ionic liquid and the aqueous phase containing gold (III) and / or palladium (II) is preferably 0.01-0.1 mmol:5 mL, more preferably 0.05 mmol:5 mL; the total concentration of gold (III) and palladium (II) in the aqueous phase containing gold (III) and / or palladium (II) is preferably 0.5-30 mmol / L. In specific embodiments, the concentration of gold (III) in the aqueous phase or the concentration of palladium (II) in the aqueous phase can be 0.5, 1, 2, 3, 4, 5, 7.5, 10 or 30 mmol / L.

[0062] In the present invention, after the ionic liquid and the aqueous phase containing gold (III) and / or palladium (II) are mixed, the ionic liquid and the metal solution (the aqueous phase containing gold (III) and / or palladium (II)) form a homogeneous phase without additional heating. The temperature for the mixed oscillation extraction is preferably 25° C., and the time is preferably 30 seconds to 3 hours, more preferably 10 minutes to 3 hours.

[0063] In the present invention, after obtaining the ionic liquid containing gold (III) and / or palladium (II) and the raffinate aqueous phase, preferably also includes back extraction, comprising the following steps:

[0064] The ionic liquid containing gold (III) and / or palladium (II) and the thiourea solution are mixed and shaken, the obtained mixed solution, the raffinate aqueous phase and the bis(trifluoromethylsulfonyl)imide salt are mixed for regeneration, the aqueous phase is removed, the organic phase is washed, and the recovered ionic liquid is obtained.

[0065] The concentration of the thiourea solution is preferably 0.05-0.1 mol / L, and the amount of the ionic liquid containing gold (III) and / or palladium (II) and the thiourea solution is preferably 0.01-0.1 mmol:5 mL, more preferably 0.05 mmol:5 mL.

[0066] The molar ratio of the mixed solution to the bis(trifluoromethylsulfonyl)imide salt is preferably 0.05:0.025-0.5, more preferably 1:1.

[0067] The temperature of the mixing and shaking is preferably 25° C., and the time is preferably 30 seconds to 3 hours, more preferably 10 minutes to 3 hours. In the present invention, the ionic liquid containing gold (III) and / or palladium (II) and the thiourea solution are mixed and shaken without stratification to obtain a mixed solution.

[0068] The temperature for mixing the obtained mixed solution, the raffinate aqueous phase and the bis(trifluoromethylsulfonyl)imide salt is preferably 80°C, and the time is preferably 30 minutes; after the mixing, it is preferably further included: first cooling in an ice water bath for 2 hours, and then shaking for 12 hours. After the regeneration, it is preferably further included to centrifuge the regenerated reaction solution, and the centrifugation rate is preferably 8000rpm, and the time is preferably 10 minutes. The reagent for washing the organic phase is preferably deionized water, the purpose of which is to remove residual thiourea solution and unreacted bis(trifluoromethylsulfonyl)imide salt.

[0069] When the ionic liquid after extraction contains gold (III), the thiourea solution preferably further contains HCl during stripping, and the concentration of thiourea in the thiourea solution is preferably 0.1 mol / L, and the concentration of HCl is preferably 0.1 mol / L. In the present invention, adding HCl to the thiourea solution can improve the stripping rate.

[0070] The ionic liquid of the present invention has low viscosity, is beneficial to mass transfer and diffusion in the extraction process, does not need to add organic solvent as a diluent, can construct an extraction system without organic solvent as a diluent, has high extraction efficiency, and short equilibrium time (10min to 3h), solves the problem of high viscosity of current ionic liquids and obstructed mass transfer in the extraction process, can eliminate environmental pollution caused by volatilization of organic solvents, and increases production safety.

[0071] In order to further illustrate the present invention, the ionic liquid provided by the present invention, its preparation method and application, and the method for extracting gold (III) and / or palladium (II) are described in detail below in conjunction with the accompanying drawings and examples, but they should not be construed as limiting the scope of protection of the present invention.

[0072] In the following examples, unless otherwise specified, all are conventional methods.

[0073] The metal mother solution used in the following embodiments is a hydrochloric acid solution containing gold, palladium and / or other metal ions.

[0074] After the extraction and separation process is completed, the concentrations of gold (III) and palladium (II) or other metals in the raffinate are measured by atomic absorption spectrometer (AA-6880) or inductively coupled plasma spectrometer (ICAP-7850). The extraction rate is calculated according to the following formula:

[0075]

[0076] Among them, n in and n eq (mmol) are the amounts of metal ions in the aqueous phase before and after extraction, respectively.

[0077] Example 1

[0078] 1. Synthesis of [diHTP][Tf2N]

[0079] In the first step, 60 mmol of thiomorpholine, 126 mmol of bromohexane and 100 mL of acetonitrile were added to a 250 mL eggplant-shaped bottle, the temperature was raised to 75 ° C, the reaction was condensed and refluxed for 48 hours, and the reaction was allowed to stand and cool to room temperature. After the solid precipitated, the acetonitrile was removed by vacuum distillation. The solid was washed three times with 100 mL of petroleum ether each time to obtain a silver-gray intermediate product ([diHTP][Br]).

[0080] In the second step, [diHTP][Br] was dissolved in 50 mL of dichloromethane, and then an aqueous solution (100 mL) containing 66 mmol of lithium bis(trifluoromethylsulfonyl)imide was added and reacted at room temperature for 12 h. After the reaction was complete, the upper aqueous phase was removed, and the organic phase was washed with deionized water for several times until no precipitate was generated when the AgNO3 solution was added to the washing liquid. The washed organic phase was rotary evaporated to remove the organic phase. Finally, the obtained ionic liquid was vacuum dried at 75 ° C for 48 h to obtain the final product [diHTP][Tf2N].

[0081] Figure 1 This is the hydrogen nuclear magnetic resonance spectrum of the bifunctional thiomorpholine ionic liquid.

[0082] 2. Extraction process of gold (III) and palladium (II) respectively

[0083] 1) 0.05 mmol of ionic liquid is taken to form an ionic liquid phase; chloroauric acid and palladium chloride are taken respectively, dissolved and diluted with 0.1 mol / L hydrochloric acid solution to prepare an aqueous phase with a gold (III) or palladium (II) concentration of 0.5 to 15 mmol / L.

[0084] 0.05 mmol of ionic liquid phase and 5 mL of aqueous phase were mixed and placed in a constant temperature shaker at 25°C for 3 hours to achieve extraction. After the extraction is completed, the ionic liquid (extractant) loaded with gold (III) or palladium (II) is at the bottom of the centrifuge tube, and the raffinate phase is the aqueous phase (above the centrifuge tube). The concentration of gold (III) or palladium (II) in the raffinate phase is measured.

[0085] In the above extraction and separation process, the extraction capacity of gold and palladium at different initial metal ion concentrations is shown in Table 1; Figure 2 The effect of initial metal concentration on the ability of ionic liquids to extract gold (III) and palladium (II), where A is the extraction of gold (III), B is the extraction of palladium (II), the abscissa is the initial metal concentration, and the ordinate is the maximum extraction capacity of gold (III) or palladium (II).

[0086] Table 1 Extraction capacity of gold (III) and palladium (II) by [diHTP][Tf2N] at different initial metal ion concentrations

[0087]

[0088]

[0089] When the initial metal ion concentration increases, the extraction capacity gradually increases and tends to equilibrium when the metal ion concentration reaches 10mmol / L.

[0090] 2) 0.1 mol / L, 1 mol / L and 2 mol / L hydrochloric acid solutions were used to prepare multi-metal mixed solutions (aqueous phase), the concentration of each metal ion was 5 mmol / L, and the extraction and separation process was the same as the above process 1). The extraction rate of [diHTP][Tf2N] for each metal is shown in Table 2; Figure 3 The effect of ionic liquids on the extraction rate of gold (III) and palladium (II) in simulated multi-metal solutions under different hydrochloric acid concentrations. The X-axis coordinate is the metal type, the Y-axis coordinate is the hydrochloric acid concentration, and the Z-axis coordinate is the extraction rate.

[0091] Table 2 Extraction rate of [diHTP][Tf2N] for multi-metal mixed solution

[0092]

[0093] [diHTP][Tf2N] has excellent selectivity for both palladium(II) and gold(III), but not for other metals (PtCl6 2- ,Al 3+ Mg 2+ ,Mn 2+ ,Cu 2+ ,Cd 2+ ,Co 2+ ,Fe 3+ ,Ni 2+ and Zn 2+ ) are all less than 5%, so the pure ionic liquid extraction system constructed by the bifunctional ionic liquid [diHTP][Tf2N] and the aqueous phase has a good selectivity for palladium (II) and gold (III), indicating that the ionic liquid described in the present invention has broad application prospects in the recovery of palladium (II) and gold (III) in a complex secondary resource environment.

[0094] 3. Stripping of palladium (II) and gold (III) respectively

[0095] 1) Stripping of palladium (II)

[0096] 0.05mmol ionic liquid and 5mL aqueous phase (0.1mol / L hydrochloric acid solution, containing PdCl4 2- The mixture was mixed with 5 mmol / L of the mixture, placed in a constant temperature shaker at 25°C for 3 h, and separated into layers to obtain a palladium extract and a raffinate, respectively.

[0097] 0.05mol / L thiourea solution (5mL) was added to the palladium extract and vibrated for 3h to achieve stripping to obtain a mixture of thiourea solution and ionic liquid (stripping solution). After stripping, the ionic liquid cannot be directly reused. The stripping solution needs to be mixed with the raffinate (5mL) at 80°C and 0.05mmol LiTf2N is added to ensure sufficient reaction. Then, the above mixture is cooled in an ice-water bath for 2h and vibrated for 12h until the regeneration reaction is completed. The regenerated reaction solution is centrifuged for 10min (8000rpm) to ensure that the two phases are completely separated and then the upper aqueous phase is removed. The ionic liquid is washed with deionized water to remove the residual thiourea solution and unreacted LiTf2N. The treated ionic liquid is used for subsequent extraction-stripping cycle experiments. It is calculated that the stripping rate of palladium (II) is 98%.

[0098] Figure 4 The results of repeated use of ionic liquids to extract gold (III) and palladium (II), where A is the extraction of gold (III), B is the extraction of palladium (II), the horizontal axis is the number of cycles, and the vertical axis is the extraction rate. [diHTP][Tf2N] exhibits excellent extraction performance for palladium (II), with the fifth extraction rate being 99.41%. The extraction rate did not drop to 79.4% until the sixth extraction-stripping cycle.

[0099] 2) Stripping of gold (III)

[0100] 0.05mmol ionic liquid and 5mL aqueous phase (0.1mol / L hydrochloric acid solution, containing AuCl4 - The mixture was mixed with 5 mmol / L of the mixture, placed in a constant temperature shaker at 25°C for 3 h, and separated into layers to obtain a gold extract and a raffinate, respectively.

[0101] A mixed solution (5 mL) containing 0.1 mol / L thiourea and 0.1 mol / L HCl was added to the gold extract and shaken for 3 h to achieve stripping to obtain a mixed solution (stripping solution). After stripping, the ionic liquid cannot be directly reused. The stripping solution and the raffinate need to be mixed at 80 ° C and 0.05 mmol LiTf2N is added to ensure sufficient reaction. Then, the above mixture is cooled in an ice water bath for 2 h and shaken for 12 h until the regeneration reaction is completed. The regenerated reaction solution is centrifuged for 10 min (8000 rpm) to ensure that the two phases are completely separated and then the upper aqueous phase is removed. The ionic liquid is washed with deionized water to remove the residual thiourea solution and unreacted LiTf2N. The treated ionic liquid is used for subsequent extraction-stripping cycle experiments. It is calculated that the stripping rate of gold (III) is about 100%.

[0102] like Figure 4As shown, [diHTP][Tf2N] exhibits excellent extraction performance for gold (III), with an extraction rate of 98.96% in the fifth extraction and stripping cycle, which only dropped to 78.0% in the sixth extraction-stripping cycle.

[0103] Example 2

[0104] 1. Synthesis of [diOTP][Tf2N]

[0105] In the first step, 60 mmol of thiomorpholine, 126 mmol of bromooctane and 100 mL of acetonitrile were added to a 250 mL eggplant-shaped bottle, the temperature was raised to 75 ° C, the reaction was condensed and refluxed for 48 hours, and the reaction was allowed to stand and cool to room temperature. After the solid was precipitated, the acetonitrile was removed by vacuum distillation. The solid was washed with petroleum ether several times to obtain a silver-gray intermediate product ([diOTP][Br]).

[0106] In the second step, [diOTP][Br] was dissolved in 50 mL of dichloromethane, and then 66 mmol of lithium bis(trifluoromethylmethanesulfonyl)amide aqueous solution was added and reacted at room temperature for 12 hours. After the reaction was complete, the upper aqueous phase was removed and the organic phase was washed with deionized water several times. The washed organic phase was rotary evaporated to remove the organic phase. Finally, the obtained ionic liquid was vacuum dried at 75°C for 48 hours to obtain the final product [diOTP][Tf2N].

[0107] Figure 1 This is the hydrogen nuclear magnetic resonance spectrum of the bifunctional thiomorpholine ionic liquid.

[0108] 2. Extraction process of gold (III) and palladium (II) respectively

[0109] Chloroauric acid and palladium chloride are taken separately, dissolved and diluted with 0.1 mol / L hydrochloric acid solution to prepare an aqueous phase with a gold (III) or palladium (II) concentration of 0.5 to 15 mmol / L.

[0110] The ionic liquid phase and the aqueous phase are mixed and placed in a shaker, and the extraction process is the same as in Example 1. After the extraction is completed, the ionic liquid loaded with gold (III) or palladium (II) is at the bottom of the centrifuge tube, and the raffinate phase is the aqueous phase (above the centrifuge tube). The concentration of gold (III) or palladium (II) in the raffinate phase is measured.

[0111] In the above extraction and separation process, the ability to extract palladium at different initial metal ion concentrations is shown in Table 3 below; Figure 2 The effect of initial metal concentration on the ability of ionic liquids to extract gold (III) and palladium (II), where A is the extraction of gold (III), B is the extraction of palladium (II), the abscissa is the initial metal concentration, and the ordinate is the maximum extraction capacity of gold (III) or palladium (II).

[0112] Table 3 Extraction capacity of gold (III) and palladium (II) by [diOTP][Tf2N] at different initial metal ion concentrations

[0113]

[0114] As the initial metal ion concentration increased, the extraction capacity gradually increased and approached equilibrium.

[0115] Example 3

[0116] 1. Synthesis of [diDTP][Tf2N]

[0117] In the first step, 60 mmol of thiomorpholine, 126 mmol of bromodecane and 100 mL of acetonitrile were added to a 250 mL eggplant-shaped bottle, the temperature was raised to 75 ° C, the reaction was condensed and refluxed for 48 hours, and the reaction was allowed to stand and cool to room temperature. After the solid precipitated, the acetonitrile was removed by vacuum distillation. The solid was washed with petroleum ether several times to obtain a silver-gray intermediate product ([diDTP][Br]).

[0118] In the second step, [diDTP][Br] was dissolved in 50 mL of dichloromethane, and then 66 mmol of lithium bis(trifluoromethylmethanesulfonyl)amide aqueous solution was added and reacted at room temperature for 12 hours. After the reaction was complete, the upper aqueous phase was removed and the organic phase was washed with deionized water several times. The washed organic phase was rotary evaporated to remove the organic phase. Finally, the obtained ionic liquid was vacuum dried at 75°C for 48 hours to obtain the final product [diDTP][Tf2N].

[0119] Figure 1 This is the hydrogen nuclear magnetic resonance spectrum of the bifunctional thiomorpholine ionic liquid.

[0120] 2. Extraction process of gold (III) and palladium (II) respectively

[0121] Chloroauric acid and palladium chloride are taken separately, dissolved and diluted with 0.1 mol / L hydrochloric acid solution to prepare an aqueous phase with a gold (III) or palladium (II) concentration of 0.5 to 15 mmol / L.

[0122] The ionic liquid phase and the aqueous phase are mixed and placed in a shaker, and the extraction process is the same as in Example 1. After the extraction is completed, the ionic liquid loaded with gold (III) or palladium (II) is at the bottom of the centrifuge tube, and the raffinate phase is the aqueous phase (above the centrifuge tube). The concentration of gold (III) or palladium (II) in the raffinate phase is measured.

[0123] In the above extraction and separation process, the ability to extract palladium at different initial metal ion concentrations is shown in Table 4 below; Figure 2The effect of initial metal concentration on the ability of ionic liquids to extract gold (III) and palladium (II), where A is the extraction of gold (III), B is the extraction of palladium (II), the abscissa is the initial metal concentration, and the ordinate is the maximum extraction capacity of gold (III) or palladium (II).

[0124] Table 4 Extraction capacity of gold (III) and palladium (II) by [diOTP][Tf2N] at different initial metal ion concentrations

[0125]

[0126] As the initial metal ion concentration increased, the extraction capacity gradually increased and approached equilibrium.

[0127] The present invention introduces functional atomic sulfur into the cation framework of the ionic liquid, so that the ionic liquid has not only ion exchange function but also coordination function for gold (III) and palladium (II). - and PdCl4 2- It will preferentially react with N in the ionic liquid + Ion exchange is achieved by combining electrostatic attraction. When the anions are completely exchanged, they are coordinated with the functional atomic sulfur on the cationic skeleton to form a stable extractant. The ionic liquid of the present invention shows excellent selectivity and reusability for gold (III) and palladium (II), providing a new option for efficient and green separation of gold (III) and palladium (II), showing excellent industrial application potential.

[0128] Although the above-mentioned embodiments have made a detailed description of the present invention, they are only some embodiments of the present invention, rather than all embodiments. People can also obtain other embodiments based on the embodiments of the present invention without creative work, and these embodiments all fall within the scope of protection of the present invention.

Claims

1. An ionic liquid, characterized in that The structural formula is shown in Formula 1: In Formula 1, n=5, 7 or 9.

2. The method for preparing the ionic liquid according to claim 1, characterized in that: The following steps are involved: Mixing thiomorpholine, halogenated alkane and acetonitrile for quaternization reaction, removing acetonitrile, and obtaining an intermediate; the halogenated alkane includes halogenated hexane, halogenated octane or halogenated decane; The intermediate is dissolved in an organic solvent, and mixed with an aqueous solution of bistrifluoromethylsulfonyl imide salt to carry out anion exchange reaction to obtain an ionic liquid.

3. The preparation method according to claim 2, characterized in that: The molar ratio of the thiomorpholine to the halogenated alkane is 1:2 to 1:2.

5.

4. The preparation method according to claim 2 or 3, characterized in that: The temperature of the quaternization reaction is 70-80° C. and the time is 36-48 hours.

5. The preparation method according to claim 2, characterized in that: The molar ratio of the intermediate to the bis(trifluoromethylsulfonyl)imide salt is 1:1 to 1:1.

5.

6. The preparation method according to claim 2 or 5, characterized in that: The temperature of the anion exchange reaction is room temperature, and the time is 6 to 12 hours.

7. Use of the ionic liquid according to claim 1 or the ionic liquid obtained by the preparation method according to any one of claims 2 to 6 in the extraction of gold (III) and / or palladium (II).

8. A method for extracting gold (III) and / or palladium (II), characterized in that: The following steps are involved: The ionic liquid and the aqueous phase containing gold (III) and / or palladium (II) are mixed and shaken for extraction, and the layers are separated to obtain a lower layer of the ionic liquid containing gold (III) and / or palladium (II) and an upper layer of the raffinate aqueous phase; The ionic liquid is the ionic liquid according to claim 1 or the ionic liquid obtained by the preparation method according to any one of claims 2 to 6.

9. The method according to claim 8, characterized in that The solvent of the aqueous phase containing gold (III) and / or palladium (II) is a hydrochloric acid solution, and the concentration of HCl in the hydrochloric acid solution is 0.1-4 mol / L.

10. The method according to claim 8 or 9, characterized in that: The dosage ratio of the ionic liquid to the aqueous phase containing gold (III) and / or palladium (II) is 0.01-0.1 mmol:5 mL, and the total concentration of gold (III) and palladium (II) in the aqueous phase containing gold (III) and / or palladium (II) is 0.5-30 mmol / L.

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