Aromatic ether compound, preparation method and application thereof, and method for recovering precious metal through solvent extraction

Abstract

The invention belongs to the technical field of recovery of precious metals through a solvent extraction method, and particularly relates to an aromatic ether compound, a preparation method and application thereof and a method for recovering precious metals through solvent extraction. The aromatic ether compound provided by the invention has a structure as shown in formula 1, has the advantages of high extraction rate and good selectivity when being used as an extraction agent for recovering noble metals in an aqueous solution by a solvent extraction method, can be repeatedly utilized, and is suitable for industrial popularization and application. # imgabs0 #

Description

Technical Field

[0001] The invention belongs to the technical field of recovering precious metals by solvent extraction, and specifically relates to an aromatic ether compound and a preparation method and application thereof, and a method for recovering precious metals by solvent extraction. Background Art

[0002] Precious metals such as gold and palladium are widely used in jewelry, corrosion-resistant materials, electronic technology, and chemical catalysts due to their luster, ductility, non-corrosiveness, and high stability. However, as a non-renewable resource, precious metals such as gold and palladium are rarely distributed worldwide, so secondary recycling is particularly important. Therefore, the selective recovery of gold and palladium ions from industrial wastewater has attracted the attention of many scientific researchers.

[0003] Solvent extraction has become an important means of recovering precious metals from wastewater due to its advantages of simple operation, low energy consumption, easy industrialization, and the ability to selectively separate target metals. At present, the commonly used extractants for recovering precious metals by solvent extraction include ether extractants, but their complexing ability with precious metals is still weak, resulting in a low extraction rate. Summary of the invention

[0004] In view of this, the purpose of the present invention is to provide an aromatic ether compound and its preparation method and application, and a method for recovering precious metals by solvent extraction. When the aromatic ether compound containing sulfur atoms is used as an extractant for recovering precious metals in an aqueous solution by solvent extraction, it has a high extraction rate.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] The present invention provides an aromatic ether compound having a structure shown in Formula 1:

[0007]

[0008] In Formula 1, X is -O- or -S-, Y is -O- or -S-, and X and Y are not -O- at the same time.

[0009] 2. The aromatic ether compound according to claim 1, characterized in that the aromatic ether compound is any of the following structures:

[0010]

[0011]

[0012] The present invention also provides a method for preparing the aromatic ether compound described in the above technical solution, comprising the following steps:

[0013] Mixing a phenol compound, an ether compound, a catalyst and an organic solvent, and performing an etherification reaction in a protective gas atmosphere to obtain the aromatic ether compound;

[0014] The phenol compound includes 2-methylthiophenol or 2-methoxyphenol;

[0015] The ether compound includes halogenated diethyl sulfide or halogenated diethyl ether;

[0016] When the phenol compound is 2-methoxyphenol, the ether compound is not a halogenated diethyl ether.

[0017] The present invention also provides the use of the aromatic ether compound described in the above technical solution or the aromatic ether compound prepared by the preparation method described in the above technical solution in recovering precious metals by a solvent extraction method.

[0018] The present invention also provides a method for recovering precious metals by solvent extraction, comprising the following steps:

[0019] The extractant organic phase solution and the aqueous phase solution to be recovered are mixed for extraction to obtain an extracted organic phase enriched with precious metals and a raffinate aqueous phase;

[0020] The extractant organic phase solution comprises an extractant and an organic diluent, and the extractant is the aromatic ether compound described in the above technical solution or the aromatic ether compound prepared by the preparation method described in the above technical solution.

[0021] Preferably, the organic diluent comprises one or more of kerosene, n-hexane, cyclohexane, petroleum ether, toluene, xylene and chlorinated alkanes.

[0022] Preferably, the molar concentration of the extractant in the extractant organic phase solution is 0.25-10 mmol / L.

[0023] Preferably, the noble metal includes gold and / or palladium; and the molar concentration of the noble metal in the aqueous solution to be recovered is 0.25 to 10 mmol / L.

[0024] Preferably, the volume ratio of the extractant organic phase solution to the aqueous phase solution to be recovered is 1-9:9-1.

[0025] Preferably, after obtaining the extracted organic phase enriched in precious metals, the method further comprises: mixing the extracted organic phase enriched in precious metals with an aqueous solution of a stripping agent for stripping to obtain an extracted aqueous phase enriched in precious metals and a raffinate organic phase;

[0026] The raffinate organic phase comprises an extractant and an organic diluent;

[0027] The stripping agent aqueous solution includes aqueous ammonia, or an aqueous thiourea solution, or a mixed aqueous solution of thiourea and HCl;

[0028] The raffinate organic phase is reused as an extractant organic phase solution.

[0029] The present invention provides an aromatic ether compound having a structure shown in Formula 1. The aromatic ether compound provided by the present invention introduces sulfur atoms into the structure of the compound, and the aromatic ether compound containing sulfur atoms can significantly improve its complexing ability with noble metal ions as an extractant by increasing the number of sulfur atoms, thereby being able to efficiently and selectively recover noble metal ions from an aqueous solution, and has the advantages of high extraction rate and good selectivity.

[0030] From the results of the examples, it can be seen that the aromatic ether compound of the structure shown in Formula 1 provided by the present invention is used as an extractant: toluene is used as an organic diluent, and under 0.1mol / L HCl, 1mmol / L of the extractant extracts 1mmol / L of metal ions, and the equilibrium time required for extracting gold is 60min, and the equilibrium time required for extracting palladium is 30min, indicating that the extraction efficiency is high. The saturated extraction capacities of EEMB, EEPMS and EMPES for Au(III) are 163.7mg / g, 772.3mg / g and 1316.2mg / g, respectively; the saturated extraction capacities for Pd(II) are 176.1mg / g, 281.7mg / g and 520.3mg / g, respectively. Aromatic ether compounds containing sulfur atoms have higher selectivity and extraction rate than aromatic ether compounds without sulfur atoms, and they still have high selectivity and high extraction rate for Au(III) and Pd(II) as extractants under low acidity.

[0031] The invention uses a stripping agent to strip the extracted organic phase enriched with precious metals, and the obtained raffinate organic phase can be reused as an extracting agent, which is suitable for industrial promotion and application.

[0032] The present invention provides a method for preparing the aromatic ether compound described in the above technical scheme. The present invention uses 2-methylthiophenol or 2-methoxyphenol as a raw material, reacts with 2-chloroethylethyloxy or thioether, and synthesizes aromatic ether extractants with different numbers of sulfur atoms (including (2-(2-ethoxyethoxy)phenyl)(methyl)sulfane (EEPMS), ethyl(2-(2-methylthio)phenoxy)(ethyl)sulfane (EMPES)). The preparation method provided by the present invention has simple synthesis, high yield, and is suitable for industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a synthetic route diagram of the aromatic ether compounds of the present invention;

[0034] Figure 2 The figure shows the effect of organic diluent and hydrochloric acid concentration on the extraction rate of Au(III) and Pd(II);

[0035] Figure 3 The figure shows the effect of extractant concentration on the extraction of Au(III) and Pd(II);

[0036] Figure 4 The figure shows the effect of hydrogen ions and chloride ions on the extraction of Au(III) and Pd(II);

[0037] Figure 5 The extraction thermodynamic diagram of Au(III) and Pd(II);

[0038] Figure 6 The extraction kinetics of Au(III) and Pd(II);

[0039] Figure 7 is the extraction capacity diagram of the extractant for Au(III) and Pd(II);

[0040] Figure 8 Job's diagram of extractant-Au(III) and extractant-Pd(II) complexes;

[0041] Fig. 9 It is the ultraviolet absorption peak diagram of ethyl (2-(2-methylthio) phenoxy) (ethyl) sulfane (EMPES) and gold and palladium complex;

[0042] Fig.10 This is a graph showing the extraction efficiency of ethyl (2-(2-methylthio)phenoxy)(ethyl)sulfane (EMPES) for simulated mixed metal ion solutions. DETAILED DESCRIPTION

[0043] The present invention provides an aromatic ether compound having a structure shown in Formula 1:

[0044]

[0045] In Formula 1, X is -O- or -S-, Y is -O- or -S-, and X and Y are not -O- at the same time.

[0046] Unless otherwise specified, the present invention has no special requirements on the sources of the raw materials used, and commercially available products known to those skilled in the art may be used.

[0047] As an embodiment, the aromatic ether compound has the structure shown in Formulas 2 to 4:

[0048]

[0049] In a specific embodiment,

[0050]

[0051] As an embodiment, the name of the aromatic ether compound represented by Formula 2 is (2-(2-ethoxyethoxy)phenyl)(methyl)sulfane (EEPMS); the name of the aromatic ether compound represented by Formula 3 is ethyl (2-(2-methylthio)phenoxy)(ethyl)sulfane (EMPES).

[0052] The aromatic ether compound provided by the present invention introduces sulfur atoms into the structure of the compound. The aromatic ether compound containing sulfur atoms can significantly improve its complexing ability with noble metal ions as an extractant by increasing the number of sulfur atoms, so that the noble metal ions (Au(III) and Pd(II)) can be efficiently and selectively recovered from the aqueous solution. The compound has the advantages of high extraction efficiency, good selectivity, high extraction rate and saturation capacity, and good acid resistance, and can be reused, so it is suitable for industrial promotion and application.

[0053] The present invention also provides a method for preparing the aromatic ether compound described in the above technical solution, comprising the following steps:

[0054] Mixing a phenol compound, an ether compound, a catalyst and an organic solvent, and performing an etherification reaction in a protective gas atmosphere to obtain the aromatic ether compound;

[0055] The phenol compound includes 2-methylthiophenol or 2-methoxyphenol;

[0056] The ether compound includes halogenated diethyl sulfide or halogenated diethyl ether;

[0057] When the phenol compound is 2-methoxyphenol, the ether compound is not a halogenated diethyl ether.

[0058] As an embodiment, the halogenated diethyl sulfide includes 2-chloroethyl ethyl sulfide, 2-bromoethyl ethyl sulfide or 2-iodoethyl ethyl sulfide, and in a specific embodiment, it is 2-chloroethyl ethyl sulfide; the halogenated diethyl ether includes 2-chloroethyl ethyl ether or 2-bromoethyl ethyl ether, and in a specific embodiment, it is 2-chloroethyl ethyl ether.

[0059] As an embodiment, the molar ratio of the phenol compound to the ether compound is 1-1.2:1, and in a specific embodiment, it is 1:1.

[0060] As an embodiment, the catalyst is potassium carbonate; the molar ratio of the phenol compound to the catalyst is 1-2:2-3, and in a specific embodiment is 2:3.

[0061] As an embodiment, the organic solvent is dimethyl sulfoxide; the volume ratio of the phenol compound to the organic solvent is 1 to 1.2:8, and in a specific embodiment, it is 1.1 to 1.2:8.

[0062] As an implementation mode, the protective gas is nitrogen.

[0063] As an embodiment, the temperature of the etherification reaction is 85 to 100° C., and in a specific embodiment, it is 90 to 100° C.; the time of the etherification reaction is 24 to 48 hours, and in a specific embodiment, it is 30 to 48 hours.

[0064] As an embodiment, after the etherification reaction, the method further comprises: dissolving the product obtained from the etherification reaction in an organic solvent, separating the obtained mixed solution into phases, washing the obtained organic phase, and removing water and organic solvent in sequence to obtain the aromatic ether compound; the organic solvent is ethyl acetate; the equipment used for the phase separation is a separatory funnel; the washing is washing with saturated brine until the water phase is clear; the number of washings is 2 to 3 times, and 3 times in the specific embodiment; the water removal is drying with anhydrous sodium sulfate; the organic solvent removal is rotary evaporation; the rotary evaporation temperature is 40 to 45°C, and 45°C in the specific embodiment; the rotary evaporation time is 10 to 15 minutes, and 10 minutes in the specific embodiment.

[0065] Figure 1 The present invention is a synthetic route of aromatic ether compounds. The present invention selects 2-methylthiophenol or 2-methoxyphenol as a raw material, reacts with 2-chloroethylethyloxy or thioether, and synthesizes aromatic ether extractants with different numbers of sulfur atoms (including (2-(2-ethoxyethoxy)phenyl)(methyl)sulfane (EEPMS), ethyl (2-(2-methylthio)phenoxy)(ethyl)sulfane (EMPES)).

[0066] The preparation method of the aromatic ether compound provided by the invention has simple synthesis, high yield and is suitable for industrial application.

[0067] The present invention also provides the use of the aromatic ether compound described in the above technical solution or the aromatic ether compound prepared by the preparation method described in the above technical solution in recovering precious metals by a solvent extraction method.

[0068] As an embodiment, the aromatic ether compound is or

[0069]

[0070] The present invention also provides a method for recovering precious metals by solvent extraction, comprising the following steps:

[0071] The extractant organic phase solution and the aqueous phase solution to be recovered are mixed for extraction to obtain an extracted organic phase enriched with precious metals and a raffinate aqueous phase;

[0072] The extractant organic phase solution comprises an extractant and an organic diluent, and the extractant is the aromatic ether compound described in the above technical solution or the aromatic ether compound prepared by the preparation method described in the above technical solution.

[0073] As an embodiment, the organic diluent includes one or more of kerosene, n-hexane, cyclohexane, petroleum ether, toluene, xylene and chlorinated alkanes, and in specific embodiments, it is chlorinated alkanes or toluene; the chlorinated alkanes include one or more of dichloromethane, chloroform and 1,2-dichloroethane, and in specific embodiments, it is dichloromethane or 1,2-dichloroethane.

[0074] As an embodiment, the molar concentration of the extractant in the extractant organic phase solution is 0.25 to 10 mmol / L, and in a specific embodiment, it is 1 to 5 mmol / L.

[0075] The present invention has no particular limitation on the amount of the diluent, as long as it can satisfy the molar concentration of the extractant in the organic phase solution of the extractant.

[0076] As an embodiment, the precious metal includes gold and / or palladium, and in a specific embodiment, it is Au(III) and / or Pd(II); the molar concentration of the precious metal in the aqueous solution to be recovered is 0.25-10 mmol / L, and as another embodiment, it is 0.5-5 mmol / L, and in a specific embodiment, it is 0.5-4.7 mmol / L.

[0077] As an embodiment, when the precious metal in the aqueous solution to be recovered is specifically Au (III), the molar concentration of Au (III) is 0.25 to 5 mmol / L, and in a specific embodiment, it is 1 to 2 mmol / L; when the precious metal in the aqueous solution to be recovered is specifically Pd (II), the molar concentration of Pd (II) is 0.5 to 10 mmol / L, and in a specific embodiment, it is 1 to 2 mmol / L.

[0078] As an embodiment, the aqueous solution to be recovered includes precious metals, water and inorganic strong acid; the inorganic strong acid is HCl; the molar concentration of the inorganic strong acid in the aqueous solution to be recovered is 0.1-4 mol / L, and is 0.1 mol / L in a specific embodiment; the pH value of the aqueous solution to be recovered is <7, and is 1-3 in a specific embodiment.

[0079] As an embodiment, the volume ratio of the organic phase solution of the extractant to the aqueous phase solution to be recovered is 1-9:9-1, and in another embodiment it is 1-5:5-1, and in a specific embodiment it is 1:1.

[0080] As an embodiment, the extraction temperature is room temperature, and in a specific embodiment, it is 25°C; the extraction time is ≥15min, and in a specific embodiment, it is ≥30min; the extraction is carried out under shaking conditions; the shaking speed is 210-230rpm, and in a specific embodiment, it is 230rpm.

[0081] In a specific embodiment, when the precious metal in the aqueous phase solution to be recovered is Au(III), the extractant in the organic phase solution is EMPES, and the extraction time is 60 minutes.

[0082] In a specific embodiment, when the precious metal in the aqueous phase solution to be recovered is Au(III), the extractant in the organic phase solution is EEPMS, and the extraction time is 6 hours.

[0083] In a specific embodiment, when the precious metal in the aqueous phase solution to be recovered is Pd(II), the extractant in the organic phase solution is EMPES, and the extraction time is 30 minutes.

[0084] In a specific embodiment, when the precious metal in the aqueous phase solution to be recovered is Pd(II), the extractant in the organic phase solution is EEPMS, and the extraction time is 60 minutes.

[0085] As an embodiment, after obtaining the extracted organic phase enriched in precious metals, the method further comprises: mixing the extracted organic phase enriched in precious metals with a stripping agent aqueous phase solution for stripping to obtain an extracted aqueous phase enriched in precious metals and a raffinate organic phase; the raffinate organic phase comprises an extractant and an organic diluent;

[0086] The stripping agent aqueous solution includes aqueous ammonia, or an aqueous thiourea solution, or a mixed aqueous solution of thiourea and HCl;

[0087] The raffinate organic phase is reused as an extractant organic phase solution.

[0088] As an embodiment, the molar concentration of the aqueous solution of the stripping agent is 1 to 1.5 mol / L.

[0089] In a specific embodiment, the molar concentration of NH3 in the ammonia water is 1 mol / L; the molar concentration of thiourea in the thiourea aqueous solution is 1 mol / L; the molar concentration of thiourea in the mixed aqueous solution of thiourea and HCl is 0.01 mol / L, and the molar concentration of HCl is 0.1-1 mol / L.

[0090] As an embodiment, the volume ratio of the precious metal-enriched extraction organic phase and the stripping agent aqueous phase solution is 1:1.

[0091] As an embodiment, the back-extraction temperature is room temperature; the back-extraction time is 2 to 6 hours, and in a specific embodiment, it is 2 hours.

[0092] As an implementation mode, the number of times of reuse is 3 to 5 times, and in a specific embodiment, it is 5 times.

[0093] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention, but they should not be construed as limiting the protection scope of the present invention.

[0094] The main reagents used in the following examples are shown in Table 1.

[0095] Table 1 Main reagents

[0096]

[0097]

[0098] Comparative Example 1

[0099] The synthesis steps of 1-(2-ethoxyethoxy)-2-methoxybenzene (EEMB) are as follows: in a 100 mL round-bottom flask, 2-methoxyphenol is used in an amount of 1.1 mL (10 mmol, 1 eq) as the main body, 1.1 mL (10 mmol, 1 eq) of 2-chloroethyl ethyl ether and 2.073 g (15 mmol, 1.5 eq) of potassium carbonate are added as a catalyst, and 8 mL of dimethyl sulfoxide solvent is injected. Under a nitrogen atmosphere, the reaction is carried out at 100° C. for 48 hours. After the reaction is stopped at room temperature, the product is a black liquid. After the product is dissolved in ethyl acetate solution, it is transferred to a separatory funnel for phase separation. The organic phase is washed with saturated brine until the aqueous phase is clear, anhydrous sodium sulfate is used to remove water, and then the organic solvent is removed by rotary evaporation. The rotary evaporation temperature is 45° C. and the time is 10 min. 1.441 g of the product is obtained, and the yield is 73.5%.

[0100] The structural formula of (2-ethoxyethoxy)-2-methoxybenzene (EEMB) is 1H NMR (400MHz, Chloroform-d): δ6.90 (tddd, J=11.3, 9.7, 4.8, 2.4Hz, 4H), 4.17 (dd, J=5.8, 4.7H z, 2H), 3.86 (s, 3H), 3.82 (dd, J = 5.8, 4.7Hz, 2H), 3.60 (q, J = 7.0Hz, 2H), 1.23 (t, J = 7.0Hz, 3H).

[0101] Example 1

[0102] The synthesis steps of (2-(2-ethoxyethoxy)phenyl)(methyl)sulfane (EEPMS) are as follows: In a 100mL round-bottom flask, 1.2mL (10mmol, 1eq) of 2-methylthiophenol is used as the main body, 1.1mL (10mmol, 1eq) of 2-chloroethyl ethyl ether and 2.073g (15mmol, 1.5eq) of potassium carbonate are added as a catalyst, and 8mL of dimethyl sulfoxide solvent is injected. Under a nitrogen atmosphere, the reaction is carried out at 100°C for 48h. After the reaction is stopped at room temperature, the product is a black liquid. After the product is dissolved in ethyl acetate solution, it is transferred to a separatory funnel for phase separation. The organic phase is washed with saturated brine until the aqueous phase is clear, and water is removed by anhydrous sodium sulfate. Then, the organic solvent is removed by rotary evaporation. The rotary evaporation temperature is 45°C and the time is 10min. The product is a black liquid with a yield of 1.441g and a yield of 73.5%.

[0103] 1H NMR (400MHz, Chloroform-d): δ6.90 (tddd, J=11.3, 9.7, 4.8, 2.4Hz, 4H), 4.17 (dd, J=5.8, 4.7H z, 2H), 3.86 (s, 3H), 3.82 (dd, J = 5.8, 4.7Hz, 2H), 3.60 (q, J = 7.0Hz, 2H), 1.23 (t, J = 7.0Hz, 3H).

[0104] Example 2

[0105] The synthesis steps of ethyl (2-(2-methylthio) phenoxy) (ethyl) sulfane (EMPES) are the same as those in Example 1, except that the 2-chloroethyl ethyl ether in Example 1 is replaced by 2-chloroethyl ethyl sulfide, wherein the amount of 2-chloroethyl ethyl sulfide is 1.2 mL (10 mmol, 1 eq), and the reaction solvent is DMSO. The product is a light brown liquid with a yield of 3.382 g and a yield of 79.8%.

[0106] 1H NMR (400MHz, Chloroform-d): δ7.16(dd,J=7.7,1.5Hz,1H),7.14-7.09(m,1H),6.98-6.93(m,1H),6.87-6.83( m, 1H), 4.18 (t, J = 5.1Hz, 2H), 3.85 (t, J = 5.1Hz, 2H), 3.64 (q, J = 7.0Hz, 2H), 2.42 (s, 3H), 1.24 (t, J = 7.1Hz, 3H).

[0107] Application Example 1

[0108] An organic phase solution of the extractant containing 1 mmol / L of the EEPMS prepared in Example 1 (the diluent is toluene) and an aqueous phase solution containing 1 mmol / L of Au(III) (wherein the hydrochloric acid concentration is 0.1 mol / L) are mixed in a volume ratio of 1:1 for extraction, and placed in a constant temperature oscillator at room temperature (25°C) and shaken at a speed of 230 rpm for 6 hours to obtain an organic phase enriched in precious metals and a residual aqueous phase.

[0109] Application Example 2

[0110] The difference from Application Example 1 is that the EEPMS prepared in Example 1 is replaced by the EMPES prepared in Example 2, the extraction time is 60 min, and the rest is the same as Application Example 1;

[0111] The precious metal-enriched extraction organic phase and the stripping agent aqueous phase solution (0.01 mol / L thiourea + 0.1 mol / L HCl) are mixed in a volume ratio of 1:1 for stripping. The stripping temperature is 25° C. and the time is 2 h to obtain the precious metal-enriched extraction aqueous phase and the raffinate organic phase. The raffinate organic phase is reused as an extractant.

[0112] Application Example 3

[0113] The difference from Application Example 1 is that the aqueous solution containing 1 mmol / L Au(III) is replaced by an aqueous solution containing 1 mmol / L Pd(II), the extraction time is 60 min, and the rest is the same as Application Example 1.

[0114] Application Example 4

[0115] The difference from Application Example 2 is that the aqueous solution containing 1 mmol / L Au(III) is replaced by an aqueous solution containing 1 mmol / L Pd(II), the extraction time is 30 min, and the rest is the same as Application Example 2;

[0116] The extracted organic phase enriched in precious metals and the aqueous phase solution of the stripping agent (0.01 mol / L thiourea + 1.0 mol / L HCl) were mixed in a volume ratio of 1:1 for stripping. The stripping temperature was 25° C. and the time was 2 h to obtain an aqueous phase enriched in precious metals and a raffinate organic phase. The raffinate organic phase was reused as an extractant.

[0117] Comparative application example 1

[0118] The difference from Application Example 1 is that the EEPMS prepared in Example 1 is replaced by the EEMB prepared in Comparative Example 1, and the rest is the same as Application Example 1.

[0119] Comparative Application Example 2

[0120] The difference from Application Example 3 is that the EEPMS prepared in Example 1 is replaced by the EEMB prepared in Comparative Example 1, and the rest is the same as Application Example 3.

[0121] Performance Testing

[0122] Extraction experiment

[0123] Through liquid-liquid extraction experiments, the extraction performance of the synthetic extractants of Examples 1 to 2 and Comparative Example 1 on Au (III) and Pd (II) was explored. Gold and palladium chlorides were dissolved in hydrochloric acid aqueous solution to prepare initial solutions with concentrations of 5mmol / L and 10mmol / L, respectively, and the initial solutions were diluted to 1mmol / L for standby use. A certain amount of extractant was dissolved in an organic diluent to prepare an organic phase, and a single metal ion solution containing 1mmol / LAu (III) and 1mmol / LPd (II) was used as the aqueous phase for solvent extraction. Equal volumes (5mL each) of aqueous phase and organic phase were placed in a 50mL centrifuge tube and placed in a constant temperature oscillator for 6 hours at a speed of 230rpm. All extraction experiments were carried out at room temperature (25°C). After the extraction was completed, the two phases were separated and the metal ion concentration in the aqueous phase was determined by atomic absorption flame spectrometry (AAS). According to the mass conservation theory, the concentration of metal ions in the organic phase was determined by the difference in metal ion concentration in the aqueous phase before and after extraction. The present invention systematically studies the effects of factors such as diluent, extraction time, hydrochloric acid concentration, and extractant concentration on the extraction process, and further explores the ion selectivity of the extractant and the extraction mechanism.

[0124] The calculation equation for the extraction rate (E%) of metal ions is shown in Formula 1, and the calculation equation for the distribution ratio (D) is shown in Formula 2:

[0125]

[0126] In formula 6, C in and C eq are defined as the initial concentration and equilibrium concentration of metal ions in the aqueous phase, respectively.

[0127] Stripping experiment

[0128] After the extraction, the aqueous phase and the organic phase were separated, and the loaded organic phase (5 mL) containing the metal complex was stripped with a 0.1 / 1 mol / L HCl+0.01 mol / L thiourea mixed solution (5 mL) at 25°C and 230 rpm. After the stripping, the concentration of metal ions in the aqueous phase was detected by atomic absorption spectroscopy (AAS), and the organic phase entered the next extraction-stripping cycle after washing. The stripping rate was calculated as shown in Formula 3.

[0129]

[0130] In formula 8, C in,org Defined as the equilibrium concentration of metal ions in the organic phase; C eq,aq Defined as the metal ion concentration in the aqueous phase after stripping.

[0131] (1) Effect of organic diluent

[0132] Extraction efficiency is a standard for measuring the extraction effect and is a key parameter of extraction performance. The viscosity, polarity, boiling point and volatility of the organic diluent will affect the extraction efficiency. Therefore, the present invention first investigates the effect of the organic diluent on the extraction performance. Non-polar solvents (kerosene, cyclohexane, n-hexane petroleum ether), medium polar solvents (toluene, xylene) and polar solvents (dichloromethane, 1,2-dichloromethane) are selected as organic diluents.

[0133] Prepare Au(III) and Pd(II) aqueous solutions with a hydrochloric acid concentration of 0.1 mol / L and a metal ion concentration of 1000 mg / L. Use a pipette to transfer 20 mL of the 1000 mg / L Au(III) aqueous solution and 10 mL of the 1000 mg / L Pd(II) aqueous solution into two 100 mL volumetric flasks, add 0.1 mol / L hydrochloric acid, and dilute to a constant volume to obtain a metal ion concentration of 200 mg / L Au(III) and 100 mg / L Pd(II) aqueous solutions.

[0134] Add different masses of extractants into a 25 mL volumetric flask: EEMB 24.5 mg, EEPMS 26.5 mg, EMPES 28.5 mg and dilute to volume with different diluents to obtain an extractant concentration of 5 mmol / L.

[0135] Prepare several centrifuge tubes, transfer equal volumes (5 mL each) of aqueous phase and organic phase into the centrifuge tubes, shake at 25°C and 210 rpm for 6 h, then take the aqueous phase, filter it through a filter head, and perform atomic absorption analysis.

[0136] The extraction experiment was carried out under the conditions of extractant concentration of 5mmol / L, 0.1 / 1mol / L HCl, extraction time t=6h, extraction temperature T=25℃, [Au(III)]=[Pd(II)]=1mmol / L. The results are shown in Figure 2 As shown, (a) is the effect of organic diluent on the extraction rate of Au(III), and (b) is the effect of organic diluent on the extraction rate of Pd(II).

[0137] Depend on Figure 2It can be seen that the extraction efficiency of the same extractant in different organic diluents varies greatly, indicating that organic diluents have a significant effect on the extraction of Au(III) and Pd(II). The experiment found that when cyclohexane, n-hexane, kerosene, and petroleum ether were used as diluents, the three extractants were insoluble or easily produced flocculent precipitation, so these solvents were not suitable for the extraction process; the three extractants had good solubility in toluene, xylene, dichloromethane, and 1,2-dichloroethane. EMPES has a high extraction rate (more than 97%) for both Au(III) and Pd(II) in the selected diluents; but EEPMS has a high extraction rate for both Au(III) and Pd(II) in the selected diluents except toluene; EEMB has a poor extraction effect in the diluent, less than 20%.

[0138] In summary, the extractant (EMPES) provided by the present invention has the best extraction effect among chlorinated alkanes and toluene diluents. However, because chlorinated alkanes have a lower boiling point and certain toxicity, toluene is selected as the diluent of the system for subsequent experiments.

[0139] (2) Effect of hydrochloric acid concentration

[0140] Elucidating the effect of hydrochloric acid concentration on metal extraction is of great significance for industrial applications. To study the effect of hydrochloric acid concentration on extraction, the hydrochloric acid concentration was controlled in the range of 0.1 to 4 mol / L and extraction experiments were carried out. At the same time, in order to obtain obvious extraction rules, the extractant concentration and the initial concentration of gold and palladium were fixed at 1 mmol / L.

[0141] Prepare Au(III) and Pd(II) aqueous solutions with a hydrochloric acid concentration of 0.1 mol / L and a metal ion concentration of 1000 mg / L. Use a pipette to transfer 20 mL of the 1000 mg / L Au(III) aqueous solution into a 100 mL volumetric flask, add different volumes of concentrated hydrochloric acid, dilute to volume to obtain Au(III) with a metal ion concentration of 200 mg / L, and the hydrochloric acid concentrations are 0.1, 0.5, 1, 2, 3 and 4 mol / L, respectively; the preparation method of different hydrochloric acid concentrations of palladium is the same as above. Transfer 10 mL of the 1000 mg / L Pd(II) aqueous solution and add different volumes of concentrated hydrochloric acid to adjust the hydrochloric acid concentration, dilute to volume to obtain Pd(II) aqueous solutions with hydrochloric acid concentrations of 0.1, 0.5, 1, 2, 3 and 4 mol / L, respectively, and a metal ion concentration of 100 mg / L.

[0142] Take 6 centrifuge tubes, add 5 mL of Au(III) aqueous solution with different hydrochloric acid concentrations to each centrifuge tube. Take another 6 centrifuge tubes, add 5 mL of Pd(II) aqueous solution with different acidity to each centrifuge tube.

[0143] Prepare the organic phase separately. Weigh 19.6 mg of the extractant EEMB and dilute it to 100 mL with toluene to obtain an extractant with a concentration of 1 mmol / L. The preparation methods of EEPMS and EMPES are the same as above, and the masses of the extractants are 21.2 mg and 22.8 mg respectively.

[0144] 5 mL of the prepared extractant was transferred into each of the above centrifuge tubes, and the tubes were placed in a constant temperature water bath shaker at 25°C for 6 hours. After the extraction was completed, the upper metal ion solution was taken, diluted by a corresponding multiple, and the concentration of the aqueous phase was tested with an atomic absorption spectrophotometer (AA-6680) to calculate the corresponding extraction rate.

[0145] The results are as follows Figure 2 As shown, (c) is the effect of HCl concentration on the extraction of Au(III), and (d) is the effect of HCl concentration on the extraction of Pd(II). Figure 2 The experimental conditions were: molar concentration of the extractant = 1 mmol / L, [Au(III)] = 1 mmol / L, [Pd(II)] = 1 mmol / L, and extraction time t = 6 h.

[0146] Figure 2 (c) in the figure shows that at a hydrochloric acid concentration of 0.1 mol / L, EMPES exhibits an excellent extraction effect (~89%) on Au(III), and as the hydrochloric acid concentration increases, the extraction rate of Au(III) decreases at a hydrochloric acid concentration of 2 mol / L, and then the decrease in the extraction rate decreases with increasing hydrochloric acid concentration (~8%).

[0147] Figure 2 As shown in (d), the increase of hydrochloric acid concentration is also not conducive to the extraction of Pd(II), causing the extraction rate of Pd(II) by EMPES to gradually decrease from 93% to ~50%. The extraction of Au(III) and Pd(II) by EEPMS decreases slowly with increasing concentration; EEMB has the worst effect, which is basically below 20%.

[0148] Comparing the extraction results of EEMB, EEPMS and EMPES, it was found that the extraction rates of Au(III) and Pd(II) were different, which may be attributed to the influence of the functional atoms and structure of the extractant. The ability of S atoms to participate in extraction is greater than that of O atoms, and the more sulfur atoms there are, the better the extraction effect. The results show that high hydrochloric acid concentration is not conducive to the extraction of the two precious metals by the extractant, so subsequent experiments were carried out at a hydrochloric acid concentration of 0.1 mol / L.

[0149] (3) Extractant concentration

[0150] The amount of extractant used in industrial applications greatly affects the cost of extraction. The present invention explores the effect of extractant concentration on Au(III) and Pd(II). Figure 3 As shown, (a) is the result of gold extraction agent concentration, and (b) is the extraction result of palladium. Figure 3 Experimental conditions: molar concentration of the extractant = 0.25-10 mmol / L, [Au(III)] = 1 mmol / L, [Pd(II)] = 1 mmol / L, [HCl] = 0.1 mol / L.

[0151] Depend on Figure 3 It can be seen that during the extraction of Au(III) and Pd(II), the extraction of Au(III) and Pd(II) by the extractant gradually reaches equilibrium, while EEPMS requires about 2mmol / L of extractant for Au(III). The extraction equilibrium of Pd(II) is extremely fast, and EMPES can reach equilibrium within 1mmol / L; EEPMS reaches extraction equilibrium for Au(III) and Pd(II) at 7mmol / L. EEMB has little effect on the extraction of Au(III) and Pd(II).

[0152] (4)H + and Cl - Influence

[0153] HCl is known to have a negative impact on the extraction of metal ions, so the extraction of H + and Cl - Effect of pH on the extraction of Au(III) and Pd(II). First, the effect of pH on the extraction of Au(III) and Pd(II) was discussed. The pH of the solution was adjusted with HCl and NaOH aqueous solution, with Au(III) at 1-13 and Pd(II) at 1-5. Figure 4 (a) It can be seen that pH has a greater influence on the extraction of Au(III), considering the change of metal ion form. Figure 4 (b) It can be seen that the extraction effect of Pd(II) is not affected by the change of pH value. - The concentration of H + The concentration of H + The concentration of Cl is 0.1 mol / L. - The concentration varies in the range of 0.1 to 4 mol / L.

[0154] H + and Cl - Effect of concentration on the extraction of Au(III) Figure 4 As shown in (c) and (d) in the figure, (c) is H + Effect of concentration on the extraction of Au(III) and Pd(II), (d) is Cl -Effect of concentration on the extraction of Au(III) and Pd(II). Figure 4 The experimental conditions of (a) to (d) are as follows: molar concentration of the extractant = 1 mmol / L, [Au(III)] = 1 mmol / L, [Pd(II)] = 1 mmol / L, and extraction time t = 6 h.

[0155] Follow H + With the increase of concentration, the extraction rate of Au(III) by EMPES showed a slightly decreasing trend, indicating that the extraction of Au(III) was affected by H + The concentration has little effect. - With the increase of concentration, the extraction of Au(III) first decreased rapidly and then tended to be gentle, and the downward trend was consistent with the effect of HCl. - The negative effect of concentration is mainly due to Cl - With AuCl4 - The competitive relationship between + and Cl - The influence on the extraction efficiency of Pd(II) is different from that of Au(III), e.g. Figure 4 (c) and (d) in H + The extraction rate of Pd(II) remained almost unchanged with the increase of Cl - The increase of 2H resulted in a decrease in the extraction rate of Pd(II), indicating that the extraction of Pd(II) was mainly affected by Cl - Influence. In the concentration range of 0.1~4mol / L hydrochloric acid, the main form of Pd(II) is PdCl4 2- When Cl in solution - At higher concentrations, PdCl4 2- With excess Cl - There is strong exchange competition, which is not conducive to extraction.

[0156] (5) Extraction thermodynamics

[0157] Temperature affects the distribution of Au(III) and Pd(II) between the two phases, thus affecting the extraction effect. The present invention explores the extraction thermodynamics of Au(III) and Pd(II) by the extractant. The results are as follows Figure 5 As shown, (a) is the extraction thermodynamic result of gold and palladium, and (b) is the extraction thermodynamic fitting result of gold and palladium. Figure 5 Experimental conditions: molar concentration of the extractant = 1 mmol / L, [Au(III)] = 1 mmol / L, [Pd(II)] = 1 mmol / L, [HCl] = 0.1 mol / L.

[0158] Depend on Figure 5It can be seen that in the extraction process of Au(III) and Pd(II), the extraction process of Au(III) and Pd(II) is an exothermic process. At the same time, according to the VanderHoff equation (formula), the corresponding thermodynamic parameters are fitted, and it is found that this extraction process is a spontaneous exothermic reaction.

[0159] (6) Extraction kinetics

[0160] Extraction kinetics greatly affects the efficiency and cost of extraction in industrial applications. The present invention investigates the extraction kinetics of Au(III) and Pd(II) by extractants. Figure 6 As shown, (a) is the extraction kinetics result of gold, (b) is the extraction kinetics result of palladium, (c) is the kinetic fitting of Au(III), and (d) is the kinetic fitting of Pd(II). Figure 6 Experimental conditions: molar concentration of the extractant = 1 mmol / L, [Au(III)] = 1 mmol / L, [Pd(II)] = 1 mmol / L, [HCl] = 0.1 mol / L.

[0161] from Figure 6 It can be seen that in the extraction process of Au(III) and Pd(II), the extraction kinetics of Au(III) is slow, where EMPES reaches equilibrium in 60 minutes, while EEPMS requires 6 hours. The extraction kinetics of Pd(II) is extremely fast, and EMPES can reach equilibrium within 30 minutes; EEPMS reaches extraction equilibrium in 60 minutes. EEMB has little effect on the extraction of Au(III) and Pd(II). At the same time, through pseudo-second-order linear fitting, it is shown that the extraction process conforms to the pseudo-second-order kinetic model, indicating that the extraction process is controlled by chemical reactions.

[0162] The more sulfur functional atoms there are, the greater the extraction rate of Au(III) and Pd(II). In the extraction process of Au(III) and Pd(II), sulfur atoms participate in the coordination. Au(III) and Pd(II) are soft acids, and soft acid substances tend to combine with soft base substances. Therefore, the coordination ability of the coordinating atoms in the extractant with Au(III) and Pd(II) is S>N>O. Therefore, the subsequent three extractants were used for the extraction of Au(III) for 6 hours and for the extraction of Pd(II) for 2 hours.

[0163] (7) Extractant saturation capacity

[0164] In order to explore the extraction capacity of the extractant, the present invention sets different initial concentrations of Au(III) and Pd(II) to explore the saturated extraction capacity of the extractant. The initial concentrations of the aqueous phase are 0.25-5 mmol / L Au(III) and 0.5-10 mmol / L Pd(II), respectively. Toluene containing 0.5 mmol / L of the extractant is used as the organic phase for extraction at 25°C for 6 h / 2 h. The results are shown in FIG. Figure 7 As shown, (a) is the extraction capacity of the extractant for Au(III) extraction, and (b) is the extraction capacity of the extractant for Pd(II) extraction. Figure 7 Experimental conditions: molar concentration of extractant = 0.5 mmol / L, [Au(III)] = 0.25-5 mmol / L, [Pd(II)] = 0.5-10 mmol / L, [HCl] = 0.1 mol / L.

[0165] from Figure 7 It can be seen that with the increase of Au(III) and Pd(II) concentrations in the aqueous phase, the extraction amount of the extractant continued to increase and tended to equilibrium, indicating that the extractant had reached extraction saturation. At this time, EMPES had the best effect, with a saturated extraction capacity of 1316.2 mg / g for Au(III) and 520.3 mg / g for Pd(II). The increase of sulfur functional atoms in the extractant strengthens the coordination ability of sulfur atoms with Au(III) and Pd(II), thereby improving the extraction ability.

[0166] (8) Extraction mechanism study

[0167] The molar ratio of the extractant to the complex formed by Au(III) and Pd(II) was determined by Job's continuous variable method. The concentration of the extractant in the organic phase and the concentration of Au(III) and Pd(II) in the aqueous phase were always kept at 1mmol / L. The total volume of the organic phase and the aqueous phase was fixed at 10mL. The ratio of the two phases was changed in turn. After 4h of extraction, the organic phase and the aqueous phase were separated, and the concentrations of Au(III) and Pd(II) in the aqueous phase were detected by AAS. The results are shown in Figure 2. Figure 8 As shown, (a) is the Job's diagram of the EEPMS-Au(III) complex, (b) is the Job's diagram of the extractant EEPMS-Pd(II) complex, (c) is the Job's diagram of the EMPES-Au(III) complex, and (d) is the Job's diagram of the extractant EMPES-Pd(II) complex. Figure 8 Experimental conditions: molar concentration of extractant = 1 mmol / L, [Au(III)] = [Pd(II)] = 1 mmol / L, V O+A =10mL, volume ratio of O (oil phase) / A (aqueous phase)=1~9:9~1.

[0168] like Figure 8 The EEPMS and EMPES fitting lines shown in (a) and (c) in the figure have maximum values ​​at 0.51 and 0.44, respectively. At this ratio, the Au(III) ions transferred from the aqueous phase to the organic phase are the largest, and the ratios of the extractant to Au(III) are 1:1 and 1:1.5, respectively, which means that one extractant molecule coordinates with one Au(III) during the extraction process, or two extractant molecules coordinate with three Au(III) during the extraction process. The increase of sulfur atoms is beneficial to the extraction of gold, increasing the complexation ratio of the extractant.

[0169] like Figure 8 As shown in (b) and (d), the mole fractions of EEPMS and EMPES reach maximum values ​​at 0.63 and 0.50, when the ratios of the extractant to Pd(II) are 1.5:1 and 1:1, respectively, which means that the ratio of the complex formed by EEPMS and Pd(II) is 3:2, and the ratio of the complex formed by EMPES and Pd(II) is 1:1.

[0170] The UV-Vis characterization method was used to detect the ultraviolet absorption wavelength of the extracted complex. Fig. 9 As shown, (a) is the ultraviolet absorption peak of EMPES and gold complex, and (b) is the ultraviolet absorption peak of EMPES and palladium complex. Fig. 9 (a) shows AuCl4 after extraction - The peaks of Au(III) appeared at 226nm and 313nm, the peaks of the extractant appeared at 212nm, 252nm and 287nm, and the peaks of the complex appeared at 217nm, 253nm, 287nm and 325nm. In contrast, the structure of the extractant did not change. The peak of Au(III) shifted from 313nm to 325nm, while the peak of Au(III) disappeared at 226nm, indicating that the morphology of Au(III) changed. Fig. 9 (b) shows that the maximum absorption peaks of Pd(II) appear at 208nm and 237nm, and the maximum absorption peaks of the extract appear at 252nm and 286nm. Compared with the peaks of the extractant, there is basically no shift, indicating that the structure of the extractant has not changed. The peaks of Pd(II) at 208nm and 237nm in the extract disappear, indicating that the existence form of Pd(II) has changed.

[0171] According to the above characterization data, the experimental equation is as follows:

[0172] The extraction equation of Au(III) is shown in Equation 9:

[0173]

[0174] The extraction equation of Pd(II) is shown in Equation 10:

[0175]

[0176] (9) Ion selectivity

[0177] Selective extraction of Au(III) and Pd(II) has important practical application significance. At the same time, hydrochloric acid concentration is also one of the factors affecting extraction separation. Therefore, the present invention prepares a mixed metal ion solution composed of 1mmol / L Au(III), Pd(II), Cu(II), Fe(III), Ni(II), Co(II), Pb(II) and Zn(II), and tests the extraction of precious metal ions by the extractant at 0.1mol / L, 1.0mol / L and 3.0mol / L hydrochloric acid concentrations. Fig.10 (a) is the extraction efficiency of EMPES for simulated mixed metal ion solution under different hydrochloric acid conditions. Fig.10 (b) is the extraction efficiency of EMPES for simulated mixed metal ion solution under different extractant concentration conditions. Fig.10 The experimental conditions of (a) are as follows: the molar concentration of the extractant = 1 mmol / L, the molar concentration of the above-mentioned metal ions = 1 mmol / L, [HCl] = 0.1-3 mol / L, O / A = 1, the extraction temperature is 25°C, and the extraction time is 2 h. Fig.10 (b) is the extraction of mixed metal ion solution by 1 / 3 / 5mmol / L extractant. The molar concentration of metal ions = 1mmol / L, [HCl] = 0.1mol / L, O / A = 1, the extraction temperature is 25°C, and the extraction time is 2h.

[0178] Fig.10 (a) in the figure shows the extraction results of metal ions by the extractant EMPES at different hydrochloric acid concentrations. When the aqueous hydrochloric acid concentration is 0.1 mol / L, the extraction rates of Au(III) and Pd(II) in the mixed solution by EMPES are 39.3% and 79.1%, respectively, and the extraction rates of impurity ions are all less than 11%. Therefore, the extraction of other coexisting metal ions can be ignored. As the HCl concentration increases, the extraction trends of Au(III) and Pd(II) are consistent with the effect of hydrochloric acid concentration on the experiment, that is, the extraction rate decreases under high acidity. Except for the extraction rate of Pt(IV), which increases with the increase of hydrochloric acid concentration to 12.3%, the extraction rates of other base metal ions are all less than 5%.

[0179] During the extraction process, EMPES found that the gold extraction rate was only 39.3%. Therefore, the concentration of the extractant was increased to further explore the selectivity of the extractant. The results are as follows Fig.10As shown in (b) in the figure. As the concentration of the extractant increased, the extraction rate of gold and palladium reached about 100%, and the extraction rates of other metal ions did not increase with the increase in the amount of extractant. Therefore, these results show that EMPES has good selectivity for Au(III) and Pd(II) and is not affected by other metal ions. This also shows that the extractant has great potential for separating Au(III) and Pd(II) from actual mixed metal ions.

[0180] (10) Reusability

[0181] Five centrifuge tubes were prepared for the extraction experiment. After the extraction, the aqueous phase and the organic phase were separated. Different stripping agents (5 mL) were added to the metal-loaded organic phase for stripping at 25°C and 230 rpm. After the stripping, the concentration of metal ions in the aqueous phase was detected by AAS, and the organic phase entered the next extraction-stripping cycle after washing. The reusability of EMPES was explored using the experimental model. The stripping effect of 1 mol / L ammonia water and thiourea on Au(III) and Pd(II) was explored.

[0182] The results are shown in Table 2. The stripping results show that acidic thiourea has the highest stripping rate, and the stripping rate of Au(III) and Pd(II) can reach 100%. This is because acidic thiourea solution is a stripping agent with faster kinetics and can form cationic metal-thiourea complexes. The stripping process includes the reduction of Au(III) to Au(I) by thiourea compounds, followed by the formation of Au(I)-thiourea complex Au(CS(NH2)2) 2+ In acidic thiourea solution, palladium is stripped to form PdCl2·(NH2)2CS, which can be attributed to the fact that the S atoms in thiourea prefer to bind to the soft metal palladium. The good stripping rate of acidic thiourea for Au(III) and Pd(II) indicates that the material is reusable.

[0183] Table 2 Stripping effect of different stripping agents

[0184]

[0185] From the above examples, it can be seen that the present invention successfully prepared an extractant including (2-(2-ethoxyethoxy)phenyl)(methyl)sulfane (EEPMS) and ethyl(2-(2-methylthio)phenoxy)(ethyl)sulfane (EMPES) and dissolved it in toluene for efficient and selective recovery of Au(III) and Pd(II) from aqueous solution.

[0186] The present invention determines the best extraction experimental conditions: using toluene as a diluent, under 0.1 mol / L HCl, 1 mmol / L of an extractant extracts 1 mmol / L of metal ions, the equilibrium time required for extracting gold is 60 minutes, and the equilibrium time required for extracting palladium is 30 minutes.

[0187] Under the optimal experimental conditions, the extractant provided by the invention has a saturated extraction capacity of 1316.2 mg / g for Au(III) and a saturated extraction capacity of 520.3 mg / g for Pd(II).

[0188] The present invention determines that the complexation ratio of the extractant to Au(III) is 2:3 and the complexation ratio to Pd(II) is 1:1 by Job's method. Combining experiments and instrument characterization, it is proposed that the extraction mechanism of the extractant for Au(III) and Pd(II) is an intermolecular coordination substitution mechanism.

[0189] The present invention has found through the study of selectivity experiments that the extractant has high selectivity and high extraction rate for Au(III) and Pd(II) under low acidity, and increasing the concentration of the extractant will increase the extraction rate for Au(III) and Pd(II) without extracting metal impurity ions, indicating that the extractant has excellent selectivity.

[0190] The invention proves that the extractant has the property of repeated utilization through the stripping of the acidic thiourea solution.

[0191] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention rather than all the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. An aromatic ether compound, characterized in that It has the structure shown in formula 1: In Formula 1: X is -O- or -S-, Y is -O- or -S-, and X and Y are not -O- at the same time.

2. The aromatic ether compound according to claim 1, characterized in that The aromatic ether compound has any of the following structures:

3. The method for preparing the aromatic ether compound according to claim 1 or 2, characterized in that: The following steps are involved: Mixing a phenol compound, an ether compound, a catalyst and an organic solvent, and performing an etherification reaction in a protective gas atmosphere to obtain the aromatic ether compound; The phenol compound includes 2-methylthiophenol or 2-methoxyphenol; The ether compound includes halogenated diethyl sulfide or halogenated diethyl ether; When the phenol compound is 2-methoxyphenol, the ether compound is not a halogenated diethyl ether.

4. Use of the aromatic ether compound according to claim 1 or 2 or the aromatic ether compound prepared by the preparation method according to claim 3 in recovering precious metals by solvent extraction.

5. A method for recovering precious metals by solvent extraction, characterized in that: The following steps are involved: The extractant organic phase solution and the aqueous phase solution to be recovered are mixed for extraction to obtain an extracted organic phase enriched with precious metals and a raffinate aqueous phase; The extractant organic phase solution comprises an extractant and an organic diluent, and the extractant is the aromatic ether compound according to claim 1 or 2 or the aromatic ether compound prepared by the preparation method according to claim 3.

6. The method according to claim 5, characterized in that The organic diluent includes one or more of kerosene, n-hexane, cyclohexane, petroleum ether, toluene, xylene and chlorinated alkanes.

7. The method according to claim 5, characterized in that The molar concentration of the extractant in the extractant organic phase solution is 0.25-10 mmol / L.

8. The method according to claim 5, characterized in that The noble metal includes gold and / or palladium; the molar concentration of the noble metal in the aqueous solution to be recovered is 0.25-10 mmol / L.

9. The method according to claim 5, 7 or 8, characterized in that: The volume ratio of the extractant organic phase solution to the aqueous phase solution to be recovered is 1-9:9-1.

10. The method according to claim 5, characterized in that After obtaining the extracted organic phase enriched in precious metals, the method further comprises: mixing the extracted organic phase enriched in precious metals with an aqueous solution of a stripping agent for stripping to obtain an extracted aqueous phase enriched in precious metals and a raffinate organic phase; The raffinate organic phase comprises an extractant and an organic diluent; The stripping agent aqueous solution includes aqueous ammonia, or an aqueous thiourea solution, or a mixed aqueous solution of thiourea and HCl; The raffinate organic phase is reused as an extractant organic phase solution.

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