An extractant for separating rhodium, and a preparation method and an extraction method thereof
By using [C8DABCO][NTf2] as the extractant, the stability and selectivity issues in the rhodium separation process were resolved, achieving efficient and low-cost rhodium separation and enrichment, which is suitable for the concept of green chemistry.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-05-26
- Publication Date
- 2026-03-03
AI Technical Summary
The lack of effective commercial extractants for the separation and recovery of rhodium in existing technologies leads to complex and costly rhodium recovery processes, and liquid-liquid extraction methods suffer from stability and selectivity issues during rhodium separation.
Using [C8DABCO][NTf2] as the extractant, rhodium(III) was mixed with the organic phase at room temperature. Its extraction performance under different acidities, temperatures and times was utilized, combined with a concentrated hydrochloric acid back-extraction process, to achieve efficient separation and enrichment of rhodium.
It achieves a high extraction rate of rhodium (over 80%) with minimal interference to other metals, yielding high-purity rhodium. The process is environmentally friendly and aligns with green chemistry principles.
Smart Images
Figure CN116814970B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of platinum group metal separation technology, and relates to an extractant for separating rhodium, its preparation, and extraction method. Background Technology
[0002] Rhodium (Rh) is the most expensive platinum group metal. Due to its high melting point, high strength, high wear resistance, good electrical conductivity, chemical stability, excellent corrosion resistance, and good catalytic activity, it is widely used in industrial production, medical devices, and jewelry manufacturing. For example, rhodium is extensively used as a catalyst in hydrogenation, acetic acid production, and three-way catalytic converters. With the rapid development of fuel cell technology as a vehicle power source and the increasing awareness of environmental protection, the demand for rhodium is further increasing.
[0003] However, rhodium is extremely rare, comprising only one part per billion of the Earth's crust. Rhodium recovery processes primarily involve pyrometallurgy and hydrometallurgy. Pyrometallurgical recovery is extremely complex, with expensive equipment, high energy consumption, and long cycles. Hydrometallurgy requires extensive refining of platinum group metals to concentrate and enrich them. The platinum group metal concentrate is then leached using aqua regia or hydrochloric acid with an oxidizing agent, and rhodium is further recovered through precipitation, calcination, and adsorption separation. Liquid-liquid extraction is commonly used for the recovery of other platinum group metals due to its simplicity, low cost, and ease of continuous operation. Currently, there is no commercially available extractant for rhodium. This is mainly because the form of rhodium in aqueous solution varies with the pH, aging degree, relative concentrations of rhodium and chlorine, and temperature. Therefore, rhodium recovery through extraction has always been one of the most challenging areas in the chemical industry. Summary of the Invention
[0004] To address the problems existing in the prior art, the first objective of this invention is to provide an extractant for separating rhodium, the extractant having the following structural formula:
[0005] Wherein, R1 is a substituted alkyl group.
[0006] Furthermore, R1 is a C8 straight-chain alkyl group.
[0007] Another object of the present invention is to provide a method for preparing an extractant for separating rhodium, comprising the following steps:
[0008] (1) Dissolve triethylenediamine and 1-bromooctane in ethyl acetate and stir at room temperature for 24 h;
[0009] (2) The product was centrifuged at 12,000 rpm and washed three times with ethyl acetate to obtain the intermediate product;
[0010] (3) Dissolve the intermediate product in ultrapure water, and add lithium bis(trifluoromethanesulfonyl)imide and stir for 3 hours;
[0011] (4) Wash the product of step (3) three times with ultrapure water to remove lithium bromide and unreacted lithium bis(trifluoromethanesulfonyl)imide until no bromide ions can be detected with silver nitrate solution;
[0012] (5) Dry the product in a vacuum drying oven at 60°C for 48 hours.
[0013] Based on the above scheme, preferably, the molar ratio of triethylenediamine and 1-bromooctane in step (1) is 1:1.1, and each 1 mmol of triethylenediamine corresponds to 0.8 mL of ethyl acetate.
[0014] Based on the above scheme, preferably, the molar ratio of the intermediate product and lithium bis(trifluoromethanesulfonyl)imide in step (3) is 1:(1-1.5), and each 1 mmol of intermediate product corresponds to 0.8 mL of ethyl acetate.
[0015] Another object of the present invention is to provide a method for extracting and separating rhodium using the extractant, comprising the following steps:
[0016] (1) The extractant is directly used as the organic phase;
[0017] (2) Take the mother liquor containing rhodium(III) and / or other metal ions, add hydrochloric acid and dilute with deionized water to form an aqueous phase;
[0018] (3) Place the aqueous phase and the organic phase to be separated in a constant temperature shaker and shake them to extract rhodium(III) into the organic phase;
[0019] (4) The organic phase loaded with rhodium(III) is back-extracted using concentrated hydrochloric acid.
[0020] Based on the above scheme, preferably, the amount of extractant used in step (1) is 0.01-0.08 mmol.
[0021] Based on the above scheme, preferably, the aqueous phase in step (2) is 1 ml, and the concentration of hydrochloric acid in the aqueous phase is 3-6.0 mol / L.
[0022] Based on the above scheme, preferably, the extraction temperature in step (3) is 25℃-65℃ and the extraction time is 50-120min.
[0023] Based on the above scheme, preferably, the concentration of concentrated hydrochloric acid in step (4) is 10-12 mol / L and the amount of concentrated hydrochloric acid used is 1 ml.
[0024] Compared with the prior art, the advantages and positive effects of the present invention are as follows:
[0025] 1. The extractant described in this invention has a simple structure, uses inexpensive raw materials, and exhibits excellent stability.
[0026] 2. The extractant described in this invention is a room-temperature extractant, which eliminates the need for volatile or toxic diluents during the extraction process, making it environmentally friendly and in line with green chemistry principles.
[0027] 3. The extractant provided by this invention has an extraction rate of over 80% for rhodium (III) and excellent resistance to impurity interference. It hardly extracts other base metals (copper, iron, nickel, cobalt, aluminum, magnesium), thus obtaining high-purity rhodium and achieving the separation and enrichment of rhodium. Attached Figure Description
[0028] Figure 1 Images of rhodium(III) solutions at different acidities. Detailed Implementation
[0029] To more clearly understand the purpose, features, and advantages of this invention, the invention will be further described below with reference to specific embodiments. It should be noted that the following embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.
[0030] Unless otherwise specified, the experimental methods described in the following examples are conventional methods.
[0031] The rhodium(III) mother liquor used in the following examples is a hydrochloric acid solution containing rhodium(III) and / or other metal ions.
[0032] After the extraction and separation process is completed, the metal concentrations in the solutions before and after extraction are determined by ICP-OES (Inductively Coupled Plasma Optical Emission Spectrometry). The formula used to calculate the extraction rate is as follows:
[0033]
[0034] Among them, C in and C eq (mg / L) represent the concentrations of metal ions in the initial aqueous phase and the equilibrium aqueous phase, respectively.
[0035] Unless otherwise specified, all reagents and materials used in the following examples are commercially available.
[0036] Example 1
[0037] 1. Preparation of extractant [C8DABCO][NTf2]
[0038] 50 mmol of triethylenediamine and 55 mmol of 1-bromooctane were dissolved in 40 mL of ethyl acetate and stirred at room temperature for 24 h. The product was then centrifuged at 12000 rpm and washed three times with ethyl acetate to obtain an intermediate. The intermediate was then dissolved in 50 mL of ultrapure water, and a slight excess of lithium bis(trifluoromethanesulfonyl)imide was added and stirred for 3 h. The product was washed with ultrapure water at least three times to remove lithium bromide and unreacted lithium bis(trifluoromethanesulfonyl)imide until no bromide ions were detected with silver nitrate solution. Finally, the product [C8DABCO][NTf2] was dried in a vacuum drying oven at 60 °C for 48 h.
[0039] 2. Rhodium(III) extraction process
[0040] Organic phase: 0.04 mmol of extractant [C8DABCO][NTf2] was used as the organic phase.
[0041] Preparation of the aqueous phase: Take a certain volume of the rhodium(III) mother liquor, add 12 mol of concentrated hydrochloric acid, and dilute to volume with deionized water to prepare a rhodium(III) concentration of 150 mg / L and a hydrochloric acid concentration of 4 mol / L. Then age the aqueous phase for more than one day before conducting the experiment.
[0042] The organic phase was mixed with 1 mL of rhodium(III)-containing aqueous phase in a 7 mL centrifuge tube, and then mechanically shaken at 25 °C for 5, 15, 30, 45, 60, 90, and 120 min. The aqueous phase after extraction was then separated using a filter membrane, and a certain volume of the raffinate was used to analyze the extraction rate of rhodium(III).
[0043] The extraction rates of rhodium(III) during the above extraction and separation process are shown in Table 1 under different shaking times. The extraction rate gradually increases with the extension of shaking time.
[0044] Table 1 Effect of different shaking times on the extraction rate of rhodium(III)
[0045]
[0046] Example 2
[0047] 1. Preparation of extractant [C8DABCO][NTf2]
[0048] The synthesis method of the extractant in this embodiment is specifically referred to in Example 1.
[0049] 2. Rhodium(III) extraction process
[0050] Organic phase: 0.04 mmol of extractant [C8DABCO][NTf2] was used as the organic phase;
[0051] Preparation of the aqueous phase: Seven portions of rhodium(III) mother liquor of different volumes were taken, 12 mol of concentrated hydrochloric acid was added, and the volume was adjusted with deionized water to prepare seven rhodium(III) solutions of different concentrations as the aqueous phase. The rhodium(III) concentrations were 50, 100, 150, 200, 250, 300, and 350 mg / L, and the hydrochloric acid concentration of the aqueous phase was 4 mol / L. The aqueous phases were then aged for more than one day before the experiment was conducted.
[0052] The organic phase was mixed with 1 mL of aqueous phase containing different concentrations of rhodium(III) in a 7 mL centrifuge tube, and then mechanically shaken at 25 °C for 2 h to ensure thorough mixing of the organic and aqueous phases. After centrifugation for 3 minutes, the aqueous phase after extraction was separated by a filter membrane, and a certain volume of the raffinate was measured to analyze the extraction rate of rhodium(III).
[0053] The extraction rates of rhodium(III) in the above extraction and separation process at different initial concentrations of rhodium(III) solution are shown in Table 2. This indicates that the extractant has a high extraction rate over a wide range of initial rhodium(III) concentrations.
[0054] Table 2 Extraction rates of [C8DABCO][NTf2] for different initial concentrations of rhodium(III)
[0055]
[0056] Example 3
[0057] 1. Preparation of extractant [C8DABCO][NTf2]
[0058] The synthesis method of the extractant in this embodiment is specifically referred to in Example 1.
[0059] 2. Rhodium(III) extraction process
[0060] Organic phase: 0.04 mmol of extractant [C8DABCO][NTf2] was used as the organic phase.
[0061] Preparation of the aqueous phase: Take 10 portions of a certain volume of rhodium(III) mother liquor, add different amounts of 12 mol concentrated hydrochloric acid, and dilute to volume with deionized water to prepare a rhodium(III) concentration of 150 mg / L. The hydrochloric acid concentration is shown in Table 3. Physical images of the obtained rhodium(III) solutions at different acidities are shown below. Figure 1 As shown. The aqueous phase was then aged for more than a day before the experiment was conducted.
[0062] The organic phase was mixed with 1 mL of aqueous phase containing rhodium(III) of different acidities in a 7 mL centrifuge tube, and then mechanically shaken at 25 °C for 2 h to ensure thorough mixing of the organic and aqueous phases. After centrifugation for 3 minutes, the aqueous phase was separated by a filter membrane, and a certain volume of the raffinate was measured to analyze the extraction rate of rhodium(III).
[0063] The extraction rates of rhodium(III) in the above extraction and separation process under different concentrations of rhodium(III) hydrochloric acid solutions are shown in Table 3.
[0064] Table 3. Extraction rates of rhodium(III) at different hydrochloric acid concentrations [C8DABCO][NTf2]
[0065]
[0066] Example 4
[0067] 1. Preparation of extractant [C8DABCO][NTf2]
[0068] The synthesis method of the extractant in this embodiment is specifically referred to in Example 1.
[0069] 2. Rhodium(III) extraction process
[0070] Organic phase: 0.04 mmol of extractant [C8DABCO][NTf2] was used as the organic phase.
[0071] Preparation of the aqueous phase: Take a certain volume of rhodium(III) mother liquor, add different amounts of 12 mol concentrated hydrochloric acid, and dilute to volume with deionized water to prepare a rhodium(III) concentration of 150 mg / L and a hydrochloric acid concentration of 4 mol / L. Then age the aqueous phase for more than one day and conduct the experiment.
[0072] The organic phase was mixed with 1 mL of an aqueous phase containing rhodium(III) in a 7 mL centrifuge tube, and then mechanically shaken at 25°C, 35°C, 45°C, 55°C, and 65°C for 2 h to ensure thorough mixing. The aqueous phase after extraction was then separated using a filter membrane, and a certain volume of the raffinate was measured to analyze the extraction rate of rhodium(III).
[0073] The extraction rates of rhodium(III) by [C8DABCO][NTf2] at different temperatures during the above extraction and separation process are shown in Table 4.
[0074] Table 4 Extraction rates of rhodium(III) by [C8DABCO][NTf2] at different temperatures
[0075]
[0076] Example 5
[0077] This embodiment studies the extraction rate of the extractant for rhodium(III) and other metals.
[0078] 1. Preparation of extractant [C8DABCO][NTf2]
[0079] The synthesis method of the extractant in this embodiment is specifically referred to in Example 1.
[0080] 2. Rhodium(III) extraction process
[0081] Organic phase: 0.04 mmol of extractant [C8DABCO][NTf2] was used as the organic phase.
[0082] Preparation of the aqueous phase: Take a multi-metal mixed mother liquor (Rh(III), Fe(III), Cu(II), Mg(II), Ni(II), Co(II) and Al(III)), add 12 mol of concentrated hydrochloric acid and dilute to volume with deionized water. The concentration of each metal is 200 mg / L and the concentration of hydrochloric acid is 4 mol / L. Then age the aqueous phase for more than one day before conducting the experiment.
[0083] The organic phase was mixed with 1 mL of aqueous phase containing rhodium(III) mixed metal solution in a 7 mL centrifuge tube. The mixture was then mechanically shaken at 25 °C for 2 h to ensure thorough mixing of the organic and aqueous phases. After centrifugation for 3 minutes, the aqueous phase was separated by a filter membrane. A certain volume of the raffinate was measured to analyze the extraction rate of rhodium(III).
[0084] The extraction rates of various metals in the multi-metal mixed solution described above are shown in Table 5. [C8DABCO][NTf2] exhibits very high selectivity for rhodium(III) but does not extract other base metals, indicating that [C8DABCO][NTf2] has excellent resistance to impurity interference.
[0085] Table 5. Selectivity of [C8DABCO][NTf2] for various metals
[0086]
[0087] Example 6
[0088] This embodiment describes the back-extraction separation of rhodium(III) in the extractant.
[0089] 1. Rhodium(III)-loaded organic phase: Take the rhodium(III)-loaded organic phase after extraction in Example 4.
[0090] 2. Rhodium(III) back-extraction separation process
[0091] Take the organic phase loaded with rhodium(III) after extraction in Example 4 and put it into a 7 ml centrifuge tube. Then add 1 ml of 12 mol / L concentrated hydrochloric acid solution as a back-extraction agent and mechanically shake at 25 °C for 10 min to make the organic phase and aqueous phase fully contact. It can be clearly observed that the aqueous phase turns into a pink solution. After taking a certain volume of back-extraction solution and diluting it with ultrapure water, the back-extraction rate of rhodium(III) is analyzed. The back-extraction efficiency reaches more than 87%.
[0092] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments for application in other fields. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.
Claims
1. An extraction method for separating rhodium by using an extractant, characterized in that: the structure of the extractant is as follows: the R1 is a linear alkyl group with C8; and the method comprises the following steps: S1, the extractant is directly used as an organic phase; S2, a mother liquor containing trivalent rhodium is taken, hydrochloric acid is added and diluted with deionized water to form an aqueous phase; S3, the aqueous phase to be separated and the organic phase are placed in a constant temperature shaker for oscillation, so that the trivalent rhodium is extracted into the organic phase; and S4, the organic phase loaded with trivalent rhodium is back-extracted with concentrated hydrochloric acid.
2. A preparation method of the extractant, comprising the following steps: (1) triethylenediamine and 1-bromo octane are dissolved in ethyl acetate, and stirred at room temperature for 24 hours; (2) the product is centrifuged by a 12000 rpm centrifuge, and washed with ethyl acetate for 3 times to obtain an intermediate product; (3) the intermediate product is dissolved in ultrapure water, and lithium bis-trifluoromethylsulfonimide is added and stirred for 3 hours; the molar ratio of the intermediate product to lithium bis-trifluoromethylsulfonimide in the step (3) is 1: (1-1.5); (4) the product of the step (3) is washed with ultrapure water for 3 times to remove lithium bromide and unreacted lithium bis-trifluoromethylsulfonimide, until no bromide ion is detected by using silver nitrate solution; and (5) the product is dried in a vacuum drying oven at 60°C for 48 hours. wherein R1is a substituted alkyl group; 3. In the step (1), the molar ratio of the triethylenediamine to the 1-bromo octane is 1:1.1, and 0.8 mL of ethyl acetate corresponds to 1 mmol of triethylenediamine.
4. In the S1, the amount of the extractant is 0.01-0.08 mmol.
5. In the S2, the aqueous phase is 1 mL, and the concentration of hydrochloric acid in the aqueous phase is 3-6.0 mol / L.
6. In the S3, the extraction temperature is 25-65°C, and the extraction time is 50-120 min.
7. In the S4, the concentration of the concentrated hydrochloric acid is 10-12 mol / L, and the amount of the concentrated hydrochloric acid is 1 mL. 2. The extraction method for separating rhodium using an extractant according to claim 1, characterized by: 3. The extraction method for separating rhodium using an extractant according to claim 2, characterized by: 4. The extraction method for separating rhodium using an extractant according to claim 1, characterized by: 5. The extraction method for separating rhodium using an extractant according to claim 1, characterized by: 6. The extraction method for separating rhodium using an extractant according to claim 1, characterized by: 7. The extraction method for separating rhodium using an extractant according to claim 1, characterized by: