A process for separating 212 Pb / 212 Bi from natural thorium

Abstract

This invention relates to a method for isolating thorium from natural sources. 212 Pb / 212 The Bi method belongs to the field of radionuclide separation technology. This invention uses quaternary ammonium salt-type ionic liquids to separate radionuclides... 232 Selective extraction in the Th decay chain 212 Pb / 212 Bi can be rapidly and selectively extracted from Pb via anion exchange in hydrochloric acid medium. 2+ with Bi 3+ , for Th 4+ La 3+ Ba 2+ With almost no extraction, the extraction rate for Pb²⁺ can reach 98.2%, and the Pb / Th separation factor can reach as high as 2700. Even with HCl or HClO₄ back-extraction, the extraction rate remains above 98% after 3-5 back-extractions, and the extractant can be recycled multiple times. This invention's separation method is kineticly fast, highly selective, low-cost, and scalable, obtaining Pb²⁺ from production feedstocks. 212 Pb and 212 Bi has high radiochemical purity, making it suitable for the preparation of targeted alpha therapy radionuclides and effectively solving the clinical supply shortage problem.

Description

Technical Field

[0001] This invention belongs to the field of radionuclide separation and purification technology, specifically relating to a method for separating and purifying radionuclides from natural sources using quaternary ammonium salt-type ionic liquids. 232 Rapid, efficient, and selective extraction and separation of radionuclides for targeted alpha therapy in Th. 212 Pb / 212 Bi's method. Background Technology

[0002] Targeted alpha nucleoside therapy is an important means of precision cancer treatment. 212 Pb and its daughter nuclides 212 Bi is an alpha-emitting nuclide with significant clinical value. Currently... 212 Pb / 212 Bi mainly comes from 232 U, which does not exist naturally and requires reactor preparation, is limited in supply and expensive. 232 Th resources are abundant and are used for the preparation of 212 Pb / 212 Bi is an ideal raw material.

[0003] Existing separation methods mainly use crown ethers or solid anion exchange resins, which are costly and cannot be used for simultaneous extraction. 212 Bi、 212 Pb suffers from drawbacks such as slow kinetics and limited capacity, making it difficult to meet the needs of rapid separation of short-lived nuclides. Summary of the Invention

[0004] Addressing the current technical challenges and shortcomings of existing technologies, the R&D team, through continuous experimentation, discovered that ionic liquids possess advantages such as good thermal stability, low vapor pressure, fast mass transfer kinetics, and designable structure. Furthermore, based on the anion exchange mechanism, they achieved… 212 Pb / 212 Bi and 232 There are currently no patents or mature industrial-scale technologies reported for the efficient extraction and separation of Th decay chain impurities. Therefore, after numerous experiments, the inventors explored a rapid, efficient, and low-cost method for separation. 212 Pb / 212 Bi method. This invention provides a method for separating thorium from natural thorium. 212 Pb / 212 Bi's method employs quaternary ammonium salt ionic liquid extraction and separation. 212 Pb / 212 Bi enables rapid, highly selective, and high-recovery separation of target nuclides, providing... 212 Pb / 212 This provides a new avenue for the clinical supply of Bi.

[0005] This invention provides a method for isolating thorium from natural thorium. 212 Pb / 212 Bi's method, the method comprising using a quaternary ammonium salt type ionic liquid from 232 Selective extraction in the Th decay chain 212 Pb and 212 Bi.

[0006] Furthermore, the present invention describes the separation of thorium from natural thorium. 212 Pb / 212 In Bi's method, the quaternary ammonium salt ionic liquid is selected from one or more combinations of methyltrioctylammonium chloride, benzyldodecyldimethylammonium chloride, and dimethylbisoctadecylammonium chloride.

[0007] In this invention, the chemical structural formula of the quaternary ammonium salt ionic liquid is as follows: .

[0008] Furthermore, the present invention describes the separation of thorium from natural thorium. 212 Pb / 212 The Bi method specifically includes the following steps: Step 1) Preparation of production feed liquid Add natural thorium nitrate to the first hydrochloric acid solution and let it stand for 48–96 hours. 232 The Th decay daughter products reach radioactive equilibrium, yielding an aqueous production feed solution; the HCl concentration of the first hydrochloric acid solution is 0.5~3 mol / L, and the aqueous production feed solution contains a lead chloride complex [PbCl3]. - Bismuth chloride complex [BiCl6] 3- In the initial stage of the solution formed by adding natural thorium nitrate to the first hydrochloric acid solution, the natural thorium nitrate in the solution... 232 The concentration range of Th is 1000 ppm to 3200 ppm.

[0009] Step 2) Selective extraction of Pb 2+ and Bi 3+ Weigh the extractant and add a diluent to prepare an organic phase feed solution. Add the organic phase feed solution and the aqueous production feed solution sequentially to an extraction tube and perform selective extraction of Pb in a shaker while maintaining a constant temperature. 2+ and Bi 3+ After shaking for 1 to 10 minutes to reach extraction equilibrium, a loaded organic phase is obtained; the volume ratio of the organic phase feed liquid to the aqueous production feed liquid is 1:1; the extractant is a quaternary ammonium salt type ionic liquid, and the diluent is an organic solvent type diluent.

[0010] Step 3) Back-extraction After completing step 2), a back-extraction agent is added to perform one or more back-extraction processes on the supported organic phase to recover the obtained product. 212 Pb / 212 Bi product; at the same time, the used back-extraction agent is recovered, and the used back-extraction agent is processed and recycled as a back-extraction agent; the back-extraction agent is hydrochloric acid solution or perchloric acid solution, and the oscillation time of each back-extraction process is 5~40min.

[0011] Furthermore, the present invention describes the separation of thorium from natural thorium. 212 Pb / 212 In the method of Bi, for the aqueous phase production feed liquid, 212 The radiochemical recovery rate of Pb is greater than 82.2%. 212 The radiochemical recovery rate of Bi is greater than 91.0%; Based on the proportions of substances in the aqueous production feed solution, stable lead nitrate, bismuth nitrate, thorium nitrate, lanthanum nitrate, and barium nitrate are added to a first hydrochloric acid solution with an HCl concentration of 0.5~3 mol / L to obtain an aqueous thorium simulation feed solution; in the aqueous thorium simulation feed solution, the Pb / Th separation factor ranges from 250 to 2700, and the Bi / Th separation factor ranges from 50 to 1000.

[0012] Furthermore, the present invention describes the separation of thorium from natural thorium. 212 Pb / 212 In the Bi method, in step 2), the concentration of the quaternary ammonium salt ionic liquid in the organic phase feed solution is 6.125~150 mmol / L, and the oscillation temperature is 298±1 K.

[0013] Furthermore, the present invention describes the separation of thorium from natural thorium. 212 Pb / 212 In the method of Bi, in step 2), the organic solvent-type diluent is selected from one of 1,2-dichloroethane, nitrobenzene, kerosene, xylene, and n-octanol.

[0014] In this invention, the organic solvent-based diluent is selected from one of 1,2-dichloroethane, nitrobenzene, kerosene, xylene, and n-octanol, and the shaking time is 2.5-10 min, both of which are used for further optimization of step 1) to improve the separation rate.

[0015] Furthermore, the present invention describes the separation of thorium from natural thorium. 212 Pb / 212 In the Bi method, in step 1), the lead-chlorine complex [PbCl3] is present in the aqueous production feed solution. - of 212 The Pb radioactivity ranges from 8.33 to 13.88 Bq, and the bismuth chloride complex [BiCl6] has a radioactivity of 8.33–13.88 Bq. 3- of 212 The radioactivity of Bi is 0.5~1.14 Bq.

[0016] The Bq mentioned above is a unit of radioactivity, which is the number of times an atomic nucleus decays per second. One atomic nucleus decays per second.

[0017] Furthermore, the present invention describes the separation of thorium from natural thorium. 212 Pb / 212 In the Bi method, the supported organic phase contains [PbCl3]. - [NR4] + Ionic compounds, [BiCl6] 3- [NR4]3 + Ionic compounds; in the aqueous production feed liquid, elements Th, La and Ba exist only in cationic or neutral forms, respectively.

[0018] In this invention, Pb in the aqueous production feed solution 2+ Bi 3+ In the first hydrochloric acid solution, it forms an anionic lead chloride complex [PbCl3] with chloride ions. - , Bismuth chloride complex [BiCl6] 3- Quaternary ammonium cations form a complex with lead chloride [PbCl3]. - , Bismuth chloride complex [BiCl6] 3- Formation of ionic compounds that enter the organic phase; Th 4+ La 3+ Ba 2+ Impurities remain in the aqueous phase as cations, achieving efficient separation. The mechanism of quaternary ammonium salt ionic liquid extraction of Pb(II) and Bi(III) is as follows: .

[0019] In this invention, the neutral form mentioned above refers to: neutral form = a molecular / coordination species with an overall charge of 0, which is neither positively nor negatively charged, and is a molecular solute that is completely dissolved in the aqueous phase.

[0020] Furthermore, the present invention describes the separation of thorium from natural thorium. 212 Pb / 212 In the method of Bi, in step 3), the concentration of the back-extraction agent hydrochloric acid solution is 1~6 mol / L, and the concentration of the back-extraction agent perchloric acid solution is 1~3 mol / L.

[0021] Furthermore, the present invention describes the separation of thorium from natural thorium. 212 Pb / 212 In the method of Bi, in step 3), the volume ratio of the added stripping agent to the volume of the supported organic phase is 1:1 during each stripping process.

[0022] The beneficial effects of this invention are: The present invention provides a method for separating thorium from natural thorium. 212 Pb / 212 Bi's method has the following technical advantages: The method of this invention has high selectivity for Pb. 2+ and Bi 3+ The highest extraction rate can reach 99%, and the back-extraction rate is ≥98%; for Th 4+ La 3+ Ba 2+ Impurities are almost not extracted.

[0023] The extraction method of this invention uses ultrafast kinetics, reaching extraction equilibrium within 2 minutes, and is suitable for the separation of short-lived nuclides.

[0024] (3) The method of the present invention is low cost and recyclable. The cost of the ionic liquid used in the present invention is much lower than that of crown ether, and it has excellent stability when recycled.

[0025] (4) The product obtained by the method of the present invention has high purity: Pb and Bi have high radiochemical purity, which is suitable for the preparation of targeted α therapy nuclides and effectively solves the problem of clinical supply shortage; and there are no long-lived radioactive impurities.

[0026] (5) The method of the present invention is simple and can be applied on a large scale in industry. Attached Figure Description

[0027] Figure 1 The Pb samples from Examples 4-11 and Comparative Examples 1 and 2 of this invention 2+ Bi 3+ Extraction rate bar chart; Figure 2 Pb in Embodiments 12 and 13 of the present invention 2+ Bi 3+ Extraction rate bar chart; Figure 3 Pb of Examples 14-20 of the present invention 2+ Bi 3+ Extraction rate bar chart; Figure 4 This is a schematic diagram illustrating the relationship between oscillation time and extraction efficiency in Example 21 of the present invention; Figure 5 Separation of Pb from a thorium-simulated feed solution in Example 23 of the present invention 2+ Bi 3+ A schematic diagram of the distribution ratio D and the separation factor SF extraction rate; Figure 6 This is a schematic diagram showing the distribution of Pb and Bi speciations in a first hydrochloric acid solution of HCl at different concentrations in a specific embodiment of the present invention. Figure 7 Pb of Embodiment 22 of the present invention 2+ Bi 3+ Extraction rate is illustrated in a bar graph. Figure 8 (a) is a comparison diagram of the gamma-ray energy spectrum of the product separated in Example 1 of the present invention and natural thorium; Figure 8 (b) The product separated from Example 1 of the present invention 212 γ-ray energy spectrum of Pb sample; Figure 8 (c) The product separated in Example 1 of the present invention 212 12 hours after Pb decay 212 γ-ray energy spectrum of Pb sample. Detailed Implementation

[0028] To provide a clearer understanding of the technical features, objectives, and effects of the present invention, specific embodiments are now described in detail with reference to the accompanying drawings. The described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the detailed embodiments, conventional conditions or conditions provided by the manufacturer shall apply.

[0029] In the following description, when referring to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this disclosure. open The terminology used is for the purpose of describing particular embodiments only and is not intended to limit this disclosure.

[0030] A type isolated from natural thorium 212 Pb / 212 Bi's method, the above method includes using quaternary ammonium salt type ionic liquids from 232 Selective extraction in the Th decay chain 212 Pb / 212 Bi.

[0031] In some embodiments, the quaternary ammonium salt ionic liquid is selected from one or more combinations of methyltrioctylammonium chloride, benzyldodecyldimethylammonium chloride, and dimethylbisoctadecylammonium chloride.

[0032] In some embodiments, the chemical structural formula of the quaternary ammonium salt ionic liquid is as follows: .

[0033] In some implementations, thorium is separated from natural thorium. 212 Pb / 212 The Bi method specifically includes the following steps: Step 1) Preparation of production feed liquid Add natural thorium nitrate to the first hydrochloric acid solution and let it stand for 48–96 hours. 232 The Th decay daughter products reach radioactive equilibrium, yielding an aqueous production feed solution; the HCl concentration of the first hydrochloric acid solution is 0.5~3 mol / L, and the aqueous production feed solution contains a lead chloride complex [PbCl3]. - Bismuth chloride complex [BiCl6] 3- In the initial stage of the solution formed by adding natural thorium nitrate to the first hydrochloric acid solution, the solution contains... 232 The concentration range of Th is 1000 ppm to 3200 ppm.

[0034] Step 2) Selective extraction of Pb 2+ and Bi 3+ Weigh the extractant and add diluent to prepare an organic phase feed solution. Add the organic phase feed solution and the aqueous production feed solution sequentially to the extraction tube and maintain a constant temperature in a shaker for selective extraction of Pb. 2+ and Bi 3+ After shaking for 1 to 10 minutes, extraction equilibrium is reached to obtain the loaded organic phase; the volume ratio of the above organic phase feed liquid to the aqueous production feed liquid is 1:1; the above extractant is a quaternary ammonium salt type ionic liquid, and the above diluent is an organic solvent type diluent.

[0035] Step 3) Back-extraction After completing step 2), a back-extraction agent is added to perform one or more back-extraction processes on the above-mentioned supported organic phase to recover the obtained product. 212 Pb / 212 Bi product; at the same time, the used back-extraction agent is recovered and recycled after treatment; the used back-extraction agent is hydrochloric acid solution or perchloric acid solution, and the shaking time for each back-extraction process is 5~40min.

[0036] In some embodiments, for the aqueous phase production feed liquid, 212 The radiochemical recovery rate of Pb is greater than 82.2%. 212 The radiochemical recovery rate of Bi is greater than 91.0%; In some embodiments, according to the proportion of substances in the aqueous production feed solution, stable lead nitrate, bismuth nitrate, thorium nitrate, lanthanum nitrate, and barium nitrate are added to a first hydrochloric acid solution with an HCl concentration of 0.5~3 mol / L to obtain an aqueous thorium simulation feed solution; in the aqueous thorium simulation feed solution, the Pb / Th separation factor ranges from 250 to 2700, and the Bi / Th separation factor ranges from 50 to 1000.

[0037] In some embodiments, the processing of the used back-extractant further includes: removing the back-extractant from the back-extractant using a coordinating agent. 212 Pb and 212 Bi products. If they are no longer to be recycled as back-extraction agents, they shall be disposed of in accordance with the methods for radioactive waste disposal.

[0038] In some embodiments, in step 2) above, the concentration of the quaternary ammonium salt ionic liquid in the organic phase feed solution is 6.125~150 mmol / L, and the oscillation temperature is 298±1 K.

[0039] In some embodiments, in step 2) above, the organic solvent-based diluent is selected from one of 1,2-dichloroethane, nitrobenzene, kerosene, xylene, and n-octanol.

[0040] In some embodiments, in step 1) above, the lead-chlorine complex [PbCl3] is present in the aqueous production feed solution. - of 212 The Pb radioactivity ranges from 8.33 to 13.88 Bq, and the above-mentioned bismuth chloride complex [BiCl6]... 3- of 212 The radioactivity of Bi is 0.5~1.14 Bq.

[0041] The Bq mentioned above is a unit of radioactivity, which is the number of times an atomic nucleus decays per second.

[0042] In some embodiments, the above-mentioned supported organic phase contains [PbCl3]. - [NR4] + Ionic compounds, [BiCl6] 3- [NR4]3 + Ionic compounds; in aqueous production feed solutions, elements Th, La, and Ba exist only in cation or neutral forms, respectively.

[0043] In some implementations, Pb in the aqueous production feed solution 2+ Bi 3+ In the first hydrochloric acid solution, it forms an anionic lead chloride complex [PbCl3] with chloride ions. - , Bismuth chloride complex [BiCl6] 3-Quaternary ammonium cations form a complex with lead chloride [PbCl3]. - , Bismuth chloride complex [BiCl6] 3- Formation of ionic compounds that enter the organic phase; Th 4+ La 3+ Ba 2+ Impurities remain in the aqueous phase as cations, achieving efficient separation. The mechanism of quaternary ammonium salt ionic liquid extraction of Pb(II) and Bi(III) is as follows: .

[0044] In some embodiments, in step 1) above, the speciation of Pb and Bi elements in the first hydrochloric acid solution is in the range of 0.5 mol / L to 8 mol / L, as shown in the figure. Figure 6 As shown, Pb gradually forms a highly coordinated anionic complex [PbCl4] with increasing HCl concentration. 2- Ultimately, it almost completely transforms into its anionic form; Bi readily forms high-valence anionic complexes [BiCl6]. 3- They maintain their dominant species within a relatively wide range of hydrochloric acid concentrations.

[0045] The degree of Pb complexation increases with increasing Cl⁻ concentration, while the complexation endpoint of Bi mainly stops at [BiCl₆]. 3- .

[0046] Depend on Figure 6 (a) It can be seen that Bi 3+ In hydrochloric acid media, it mainly exists as a high-chloride complex, and its complexation form varies significantly with hydrochloric acid concentration. At lower hydrochloric acid concentrations (e.g., 0.5 mol / L), [BiCl5] is the predominantly present in the system. 2- and [BiCl6] 3- [BiCl6] 3- The proportion is relatively high; as the concentration of hydrochloric acid increases, [BiCl6]... 3- The proportion continued to decline, while [BiCl5] 2- Gradually increase; when the hydrochloric acid concentration reaches approximately 5.5–6 mol / L, [BiCl5] 2- Reaching its maximum proportion, approximately 90%, it became Bi 3+ The dominant species in the system; meanwhile, [BiCl6] 3- Reduce to below approximately 5%; continue increasing the hydrochloric acid concentration, [BiCl6] 3- The proportion decreased slightly, while [BiCl4] 2- It begins to gradually increase, accounting for over 20% in 8 mol / L hydrochloric acid; in contrast, [BiCl] 2+ [BiCl2]+ Low-chlorine coordination species such as [BiCl3] maintained a low proportion throughout the entire concentration range, indicating that Bi... 3+ It exhibits strong complexing ability in a strong chloride ion environment and tends to form highly coordinated chloride complexes.

[0047] Depend on Figure 6 (b) It can be seen that Pb 2+ The chlorination behavior of Bi 3+ Significant differences exist, with the main trend being a gradual shift from low-coordination complexes to high-coordination complexes. Under low hydrochloric acid concentrations (0.5–1 mol / L), Pb… 2+ Mainly free Pb 2+ It exists in the form of low-chlorine complexes, indicating that Pb exists under weakly acidic conditions. 2+ The complexation effect is weak, mainly forming monochloro complexes; as the hydrochloric acid concentration increases, Pb... 2+ and [PbCl] + The proportions decreased rapidly, while [PbCl2] and [PbCl3]... - The proportions first increased and then decreased. Specifically, [PbCl2] reached its maximum value around 1 mol / L, and then gradually decreased; [PbCl3]... - It reaches its peak concentration at 1.5–2 mol / L; simultaneously, [PbCl4] 2- The proportion increased rapidly, and [PbCl4] became the absolutely dominant species after the hydrochloric acid concentration exceeded 4 mol / L; when the hydrochloric acid concentration reached 8 mol / L, [PbCl4]... 2- The proportion is approximately 90%, indicating that a strong chlorine environment promotes the growth of Pb. 2+ It forms a stable tetrachloro complex.

[0048] In some embodiments, in step 3) above, the concentration of the stripping agent hydrochloric acid solution is 1~6 mol / L, and the concentration of the stripping agent perchloric acid solution is 1~3 mol / L.

[0049] In some embodiments, in step 3) above, the volume ratio of the added stripping agent to the volume of the supported organic phase is 1:1 during each stripping process.

[0050] The present invention will be further described in detail below with reference to specific embodiments. Example 1

[0051] The present invention provides a method for isolating thorium from natural sources. 212 Pb / 212 The Bi method specifically includes the following steps: Step 1) Preparation of production feed liquid Add natural thorium nitrate to the first hydrochloric acid solution and let stand for 96 hours. 232The Th decay daughter products reached radioactive equilibrium, yielding an aqueous production feed solution. The first hydrochloric acid solution had an HCl concentration of 2 mol / L, and the aqueous production feed solution contained a chlorine complex [PbCl3]. - The chlorine complex [BiCl6] 3- ; In the initial stage of the solution formed by adding natural thorium nitrate to the first hydrochloric acid solution, the natural thorium nitrate in the solution... 232 The concentration range of Th is 1000 ppm; In aqueous production feed solutions, lead-chlorine complex [PbCl3] - of 212 The Pb radioactivity is 8.33, and it is a bismuth chloride complex [BiCl6]. 3- of 212 The radioactivity of Bi is 0.5 Bq.

[0052] Step 2) Selective extraction of Pb 2+ and Bi 3+ Prepare an organic phase feed solution by adding extractant and diluent. Then, sequentially add the organic phase feed solution and the aqueous production feed solution to the extraction tube and perform selective extraction of Pb in a shaker while maintaining a constant temperature. 2+ and Bi 3+ The oscillation temperature was 298 K, and extraction equilibrium was reached after oscillation for 5 min, resulting in a loaded organic phase. The volume ratio of the organic phase feed liquid to the aqueous phase production feed liquid was 1:1. The extractant was a quaternary ammonium salt type ionic liquid, and the diluent was an organic solvent type diluent. The quaternary ammonium salt ionic liquid is methyltrioctylammonium chloride, and the concentration of the quaternary ammonium salt ionic liquid in the organic phase feed solution is 150 mmol / L. The organic solvent-based diluent is 1,2-dichloroethane (DCE). The supported organic phase contains [PbCl3]. - [NR4] + Ionic compounds, [BiCl6] 3- [NR4]3 + Ionic compounds; in the supported organic phase, the elements Th, La, and Ba exist only in cation or neutral forms, respectively.

[0053] Step 3) Back-extraction After completing step 2), a back-extraction agent is added to perform a single back-extraction process on the supported organic phase to recover the obtained product. 212 Pb / 212 Bi product; at the same time, the used back-extraction agent is recovered and recycled after treatment; the back-extraction agent is hydrochloric acid solution or perchloric acid solution, and the shaking time for each back-extraction process is 30 minutes.

[0054] The concentration of the stripping agent, perchloric acid solution, is 3 mol / L.

[0055] During the back-extraction process, the volume ratio of the added back-extraction agent to the volume of the supported organic phase is 1:1.

[0056] In the method of this embodiment 1, Pb 2+ The extraction rate was 98.2%, Bi 3+ Extraction rate ≥95%, Th 4+ Extraction rate < 1%; Pb 2+ The back-extraction rate is greater than 98%, Bi 3+ The back-extraction rate is greater than 98%.

[0057] In addition, such as Figure 8 As shown, the comparison of the gamma spectral density (GDS) spectra of the separated product and natural thorium in Example 1 indicates that the product is of high purity. 212 Pb / 212 Bi, free of long-lived impurities, has a radiochemical recovery rate of 91%. Among them, Figure 8 In the image, (a) shows a comparison of the gamma-ray energy dispersive spectra of natural thorium and the separated product, and (b) shows the gamma-ray energy dispersive spectra of the prepared product. 212 The gamma-ray energy spectrum of the Pb sample, (c) is the product. 212 12 hours after Pb decay 212 Gamma-ray energy spectrum of Pb sample. Example 2

[0058] The only difference between Example 2 and Example 1 is that: In step 2), 100 mmol / L methyltrioctylammonium chloride was used for organic phase extraction, and the extraction equilibrium was reached after shaking for 10 min. In the method of this embodiment 2, Pb 2+ The extraction rate is greater than 98.5%, Bi 3+ Extraction rate ≥95%, Pb 2+ The back-extraction rate is greater than 98%, Bi 3+ The back-extraction rate is greater than 98%; 212 Pb enrichment coefficient >100, after back-extraction, it can be directly used for the preparation of targeted α-therapeutic drugs. Example 3

[0059] The only difference between Example 3 and Example 1 is that: In step 3), a 3 mol / L HClO4 perchloric acid solution is used as the back-extraction agent, and five back-extraction cycles are performed continuously.

[0060] In the method of this embodiment 3, Pb 2+ The extraction rate is greater than 98.2%, Bi 3+The extraction rate is ≥98%, the extraction efficiency remains ≥98% with no significant decline, and it has good potential for industrial application.

[0061] To further confirm the separation of natural thorium in this invention 212 Pb / 212 In the process of the Bi method, the effects of the concentration of the first hydrochloric acid (HCl), the diluent, and the extractant on the final extraction performance are discussed; as well as the relationship between the shaking time and the extraction efficiency. The following examples further verify the advantages of the method of the present invention by preparing a thorium-simulated feed solution to replace the production feed solution. Example 4

[0062] Step 1) Prepare a thorium-simulated feed solution to replace the production feed solution. Stable lead nitrate, bismuth nitrate, thorium nitrate, lanthanum nitrate, and barium nitrate were added to a first hydrochloric acid solution with an HCl concentration of 0.5 mol / L to obtain an aqueous thorium simulation solution.

[0063] The concentrations of thorium ions, lanthanum ions, barium ions, bismuth ions, and lead ions in the thorium simulation solution were 100 ppm, 100 ppm, 100 ppm, 20 ppm, and 20 ppm, respectively. The lead and bismuth ions used were in a stable state and were not radioactive.

[0064] The aqueous thorium simulation solution contained lead chloride complex [PbCl3]. - Bismuth chloride complex [BiCl6] 3- .

[0065] In the initial stage of the solution formed by adding natural thorium nitrate to the first hydrochloric acid solution, the natural thorium nitrate in the solution... 232 The concentration range of Th is 1000 ppm.

[0066] Step 2) Selective extraction of Pb 2+ and Bi 3+ Prepare an organic phase feed solution by adding extractant and diluent. Then, sequentially add the organic phase feed solution and the aqueous thorium simulation feed solution to the extraction tube and perform selective extraction of Pb in a shaker while maintaining a constant temperature. 2+ and Bi 3+ The oscillation temperature was 298 K, and extraction equilibrium was reached after oscillation for 5 min, resulting in a loaded organic phase. The volume ratio of the organic phase feed solution to the aqueous thorium simulation feed solution was 1:1. The extractant was a quaternary ammonium salt ionic liquid, and the diluent was an organic solvent-based diluent. The quaternary ammonium salt ionic liquid is methyltrioctylammonium chloride, and the concentration of the quaternary ammonium salt ionic liquid in the organic phase feed solution is 20 mmol / L.

[0067] The organic solvent-based diluent is 1,2-dichloroethane (DCE). The supported organic phase contains [PbCl3]. - [NR4] + Ionic compounds, [BiCl6] 3- [NR4]3 + Ionic compounds; in the supported organic phase, the elements Th, La, and Ba exist only in cation or neutral forms, respectively.

[0068] Step 3) Back-extraction After completing step 2), a back-extraction agent is added to perform a single back-extraction process on the supported organic phase to recover the obtained product. 212 Pb / 212 Bi product; at the same time, the used back-extraction agent is recovered and recycled after treatment; the back-extraction agent is hydrochloric acid solution or perchloric acid solution, and the shaking time for each back-extraction process is 30 minutes.

[0069] The concentration of the stripping agent, perchloric acid solution, is 3 mol / L.

[0070] In each back-extraction process, the volume ratio of the added back-extraction agent to the volume of the supported organic phase is 1:1.

[0071] like Figure 1 As shown, in the method of this embodiment 4, the allocation coefficient of Bi is 684, the allocation coefficient of Pb is 5, and Bi... 3+ The extraction rate was 99.85%, Pb 2+ The extraction rate was 83.33%.

[0072] Example 5: In Example 5, the HCl concentration of the first hydrochloric acid solution is the same as that in Example 4, but the diluent is different. The only difference is: In step 2), the organic solvent-based diluent is nitrobenzene.

[0073] In the method of this embodiment 5, such as Figure 1 As shown, the partition coefficient of Bi is 215, and the partition coefficient of Pb is 8. 2+ The extraction rate was 88.89%, Bi 3+ The extraction rate was 99.54%. Example 6

[0074] The HCl concentration of the first hydrochloric acid solution in Example 6 is different from that in Example 4, but the diluent is the same. The only difference is: In step 1), the HCl concentration of the first hydrochloric acid solution is 1 mol / L.

[0075] In the method of this embodiment 6, such as Figure 1As shown, the partition coefficient of Bi is 330, and the partition coefficient of Pb is 9.8. 2+ The extraction rate was 90.74%, Bi 3+ The extraction rate was 99.70%. Example 7

[0076] The only difference between Example 7 and Example 4 is that: In step 1), the HCl concentration of the first hydrochloric acid solution is 1 mol / L; In step 2), the organic solvent-based diluent is nitrobenzene.

[0077] In the method of this embodiment 7, such as Figure 1 As shown, the partition coefficient of Bi is 140, and the partition coefficient of Pb is 8.8. 2+ The extraction rate was 89.80%, Bi 3+ The extraction rate was 99.29%. Example 8

[0078] The only difference between Example 8 and Example 4 is that: In step 1), the HCl concentration of the first hydrochloric acid solution is 2 mol / L; In the method of this embodiment 8, such as Figure 1 As shown, the partition coefficient of Bi is 200, and the partition coefficient of Pb is 18.2. 2+ The extraction rate was 94.79%, Bi 3+ The extraction rate was 99.50%.

[0079] Example 9: The only difference between Example 9 and Example 4 is that: In step 1), the HCl concentration of the first hydrochloric acid solution is 2 mol / L; In step 2), the organic solvent-based diluent is nitrobenzene.

[0080] In the method of this embodiment 9, such as Figure 1 As shown, the partition coefficient of Bi is 100, and the partition coefficient of Pb is 9.4. 2+ The extraction rate was 90.38%, Bi 3+ The extraction rate was 99.00%.

[0081] Example 10: The only difference between Example 10 and Example 4 is that: In step 1), the HCl concentration of the first hydrochloric acid solution is 3 mol / L; In the method of this embodiment 10, such as Figure 1 As shown, the partition coefficient of Bi is 85, and the partition coefficient of Pb is 7.9.2+ The extraction rate was 88.76%, Bi 3+ The extraction rate was 98.83%.

[0082] Example 11: The only difference between Example 11 and Example 4 is that: In step 1), the HCl concentration of the first hydrochloric acid solution is 3 mol / L; In step 2), the organic solvent-based diluent is nitrobenzene.

[0083] In the method of this embodiment 11, such as Figure 1 As shown, the partition coefficient of Bi is 70, and the partition coefficient of Pb is 8.1. 2+ The extraction rate was 89.01%, Bi 3+ The extraction rate was 98.59%.

[0084] Example 12: The only difference between Example 12 and Example 4 is that: In step 1), the HCl concentration of the first hydrochloric acid solution is 2 mol / L; In step 2), the quaternary ammonium salt ionic liquid is benzyl dodecyl dimethyl ammonium chloride.

[0085] In the method of this embodiment 12, such as Figure 2 As shown, the partition coefficient of Bi is 215, and the partition coefficient of Pb is 9.5. 2+ The extraction rate was 89.80%, Bi 3+ The extraction rate was 90.48%.

[0086] Example 13: The only difference between Example 13 and Example 4 is that: In step 1), the HCl concentration of the first hydrochloric acid solution is 3 mol / L; In step 2), the quaternary ammonium salt ionic liquid is benzyl dodecyl dimethyl ammonium chloride.

[0087] In the method of this embodiment 13, such as Figure 2 As shown, the partition coefficient of Bi is 430, and the partition coefficient of Pb is 5.3. 2+ The extraction rate was 89.80%, Bi 3+ The extraction rate was 84.13%.

[0088] Example 14: The only difference between Example 14 and Example 4 is that: In step 1), the HCl concentration of the first hydrochloric acid solution is 0.5 mol / L; In step 2), the quaternary ammonium salt ionic liquid is p-bis(octadecyldimethylammonium chloride), and the organic solvent diluent is nitrobenzene.

[0089] In the method of this embodiment 14, such as Figure 3 As shown, the partition coefficient of Bi is 140, and the partition coefficient of Pb is 5.2. 2+ The extraction rate was 83.87%, Bi 3+ The extraction rate was 99.29%.

[0090] Example 15: The only difference between Example 15 and Example 4 is that: In step 1), the HCl concentration of the first hydrochloric acid solution is 1 mol / L; In step 2), the quaternary ammonium salt ionic liquid is p-bis(octadecyldimethylammonium chloride).

[0091] In the method of this embodiment 15, such as Figure 3 As shown, the partition coefficient of Bi is 230, and the partition coefficient of Pb is 6.2. 2+ The extraction rate was 86.11%, Bi 3+ The extraction rate was 99.57%.

[0092] Example 16: The only difference between Example 16 and Example 4 is that: In step 1), the HCl concentration of the first hydrochloric acid solution is 1 mol / L; In step 2), the quaternary ammonium salt ionic liquid is p-bis(octadecyldimethylammonium chloride), and the organic solvent diluent is nitrobenzene.

[0093] In the method of this embodiment 16, such as Figure 3 As shown, the partition coefficient of Bi is 95, and the partition coefficient of Pb is 5.8. 2+ The extraction rate was 85.29%, Bi 3+ The extraction rate was 98.96%.

[0094] Example 17: The only difference between Example 17 and Example 4 is that: In step 1), the HCl concentration of the first hydrochloric acid solution is 2 mol / L; In step 2), the quaternary ammonium salt ionic liquid is p-bis(octadecyldimethylammonium chloride).

[0095] In the method of this embodiment 17, such as Figure 3 As shown, the partition coefficient of Bi is 130, the partition coefficient of Pb is 12.3, and the partition coefficient of Pb is... 2+The extraction rate was 94.48%, Bi 3+ The extraction rate was 99.24%.

[0096] Example 18: The only difference between Example 18 and Example 4 is that: In step 1), the HCl concentration of the first hydrochloric acid solution is 2 mol / L; In step 2), the quaternary ammonium salt ionic liquid is p-bis(octadecyldimethylammonium chloride), and the organic solvent diluent is nitrobenzene.

[0097] In the method of this embodiment 18, such as Figure 3 As shown, the partition coefficient of Bi is 70, and the partition coefficient of Pb is 6.4. 2+ The extraction rate was 86.49%, Bi 3+ The extraction rate was 98.59%.

[0098] Example 19: The only difference between Example 19 and Example 4 is that: In step 1), the HCl concentration of the first hydrochloric acid solution is 3 mol / L; In step 2), the quaternary ammonium salt ionic liquid is p-bis(octadecyldimethylammonium chloride).

[0099] In the method of this embodiment 19, such as Figure 3 As shown, the partition coefficient of Bi is 55, the partition coefficient of Pb is 5.1, and the partition coefficient of Pb is... 2+ The extraction rate was 98.21%, Bi 3+ The extraction rate was 99.24%.

[0100] Example 20: The only difference between Example 20 and Example 4 is that: In step 1), the HCl concentration of the first hydrochloric acid solution is 3 mol / L; In step 2), the quaternary ammonium salt ionic liquid is p-bis(octadecyldimethylammonium chloride), and the organic solvent diluent is nitrobenzene.

[0101] In the method of this embodiment 20, such as Figure 3 As shown, the partition coefficient of Bi is 49, the partition coefficient of Pb is 5.5, and the partition coefficient of Pb is... 2+ The extraction rate was 84.62%, Bi 3+ The extraction rate was 98.00%.

[0102] Example 21: The only difference between Example 21 and Example 4 is that: In step 2), the extraction was performed with shaking times of 1 min, 2.5 min, 7.5 min, and 10 min, respectively, and the results are as follows: Figure 4 As shown.

[0103] Bi in this embodiment 21 3+ Extraction rate and Pb 2+ Extraction rate such as Figure 4 As shown, and the Bi oscillation time of 5 min in Example 1. 3+ Extraction rate and Pb 2+ The extraction rate is also like Figure 4 As shown; Pb 2+ The extraction rate is >87.00%, Bi 3+ The extraction rate is >91.00%.

[0104] Example 22: The only difference between Example 22 and Example 4 is that: In step 3), after completing step 2), a back-extraction agent is added to perform 1, 2 and 3 back-extraction processes on the supported organic phase, respectively.

[0105] like Figure 7 As shown in Example 22, Pb 2+ The back-extraction rate is greater than 98%, Bi 3+ The back-extraction rate is 98%.

[0106] Example 23: The only difference between Example 23 and Example 4 is that: In step 1), Pb was separated from the thorium simulation feed solution by taking HCl concentrations of 0.5 mol / L, 1 mol / L, 2 mol / L, and 3 mol / L from the first hydrochloric acid solution. 2+ Bi 3+ The distribution ratio D and separation factor SF, the elemental configuration in the thorium simulated feed solution is [Th 4+ [Pb] = 100 mg / L 2+ =90 mg / L, [Bi 3+ =90 mg / L, [Ba 2+ =60 mg / L, [La 3+ =60 mg / L; the result is as follows Figure 5 As shown, it can be seen that with 2 mol / L hydrochloric acid, a lead-thorium separation factor close to 2700 is obtained, the Pb / Th separation factor ranges from 250 to 2700, and the Bi / Th separation factor ranges from 50 to 1000.

[0107] Comparative Example 1: The only difference between Comparative Example 1 and Example 4 is that: In step 1), the HCl concentration of the first hydrochloric acid solution is 0.1 mol / L; In the method of Comparative Example 1, such as Figure 1 As shown, Pb 2+ The extraction rate was 75.00%.

[0108] Comparative Example 2: The only difference between Comparative Example 2 and Example 5 is that: In step 1), the HCl concentration of the first hydrochloric acid solution is 0.1 mol / L; In the method of this comparative example 2, such as Figure 1 As shown, Pb 2+ The extraction rate was 71.43%, Bi 3+ The extraction rate was 90.91%.

[0109] Comparative Example 3: The only difference between Comparative Example 3 and Example 12 is that: In step 1), the HCl concentration of the first hydrochloric acid solution is 0.1 mol / L; In the method of Comparative Example 3, Pb 2+ The extraction rate was 50.00%, Bi 3+ The extraction rate was 98.99%.

[0110] Comparative Example 4: The only difference between Comparative Example 4 and Example 18 is that: In step 1), the HCl concentration of the first hydrochloric acid solution is 0.1 mol / L; In the method of Comparative Example 4, Pb 2+ The extraction rate was 71.43%, Bi 3+ The extraction rate was 93.75%.

[0111] Comparative Example 5: The only difference between Comparative Example 5 and Example 19 is that: In step 1), the HCl concentration of the first hydrochloric acid solution is 0.1 mol / L; In the method of Comparative Example 5, Pb 2+ The extraction rate was 66.67%, Bi 3+ The extraction rate was 88.89%.

[0112] This invention has been described through the specific embodiments described above. Those skilled in the art should understand that various modifications and equivalent substitutions can be made to this invention without departing from its scope. Parts not described in detail in this specification are well-known to those skilled in the art. Furthermore, various modifications can be made to this invention for specific situations or circumstances without departing from its scope. Therefore, this invention is not limited to the specific embodiments disclosed, but should include all embodiments falling within the scope of the claims.

Claims

1. A method for isolating thorium from natural sources 212 Pb / 212 The method of Bi is characterized by, The method includes using a quaternary ammonium salt ionic liquid from 232 Selective extraction in the Th decay chain 212 Pb and 212 Bi.

2. The method for separating thorium from natural thorium according to claim 1 212 Pb / 212 The method of Bi is characterized by, The quaternary ammonium salt type ionic liquid is selected from one or more combinations of methyltrioctylammonium chloride, benzyldodecyldimethylammonium chloride, and dimethylbisoctadecylammonium chloride.

3. The method for separating thorium from natural thorium according to claim 2 212 Pb / 212 The method of Bi is characterized by, The method specifically includes the following steps: Step 1) Preparation of production feed liquid Add natural thorium nitrate to the first hydrochloric acid solution and let it stand for 48–96 hours. 232 The Th decay daughter products reach radioactive equilibrium, yielding an aqueous production feed solution; the HCl concentration of the first hydrochloric acid solution is 0.5~3 mol / L, and the aqueous production feed solution contains a lead chloride complex [PbCl3]. - Bismuth chloride complex [BiCl6] 3- In the initial stage of the solution formed by adding natural thorium nitrate to the first hydrochloric acid solution, the solution contains... 232 The concentration range of Th is 1000 ppm to 3200 ppm; Step 2) Selective extraction of Pb 2+ and Bi 3+ Weigh the extractant and add a diluent to prepare an organic phase feed solution. Add the organic phase feed solution and the aqueous production feed solution sequentially to an extraction tube and perform selective extraction of Pb in a shaker while maintaining a constant temperature. 2+ and Bi 3+ After shaking for 1-10 minutes to reach extraction equilibrium, a loaded organic phase is obtained; the volume ratio of the organic phase feed liquid to the aqueous production feed liquid is 1:1; the extractant is a quaternary ammonium salt type ionic liquid, and the diluent is an organic solvent type diluent; Step 3) Back-extraction of Pb 2+ and Bi 3+ After completing step 2), a back-extraction agent is added to perform one or more back-extraction processes on the supported organic phase to recover the obtained product. 212 Pb / 212 Bi product; and simultaneously recover the used back-extraction agent, which is then processed and recycled as a back-extraction agent; the back-extraction agent is a hydrochloric acid solution or a perchloric acid solution, and the oscillation time for each back-extraction process is 5 to 40 minutes.

4. The method for separating thorium from natural thorium according to claim 3. 212 Pb / 212 The method of Bi is characterized by, For the aforementioned aqueous production feed liquid 212 The radiochemical recovery rate of Pb is greater than 82.2%. 212 The radiochemical recovery rate of Bi is greater than 91.0%; Based on the proportions of substances in the aqueous production feed solution, stable lead nitrate, bismuth nitrate, thorium nitrate, lanthanum nitrate, and barium nitrate are added to a first hydrochloric acid solution with an HCl concentration of 0.5~3 mol / L to obtain an aqueous thorium simulation feed solution; in the aqueous thorium simulation feed solution, the Pb / Th separation factor ranges from 250 to 2700, and the Bi / Th separation factor ranges from 50 to 1000.

5. The method for separating thorium from natural thorium according to claim 3. 212 Pb / 212 The method of Bi is characterized by, In step 2), the concentration of the quaternary ammonium salt ionic liquid in the organic phase feed solution is 6.125~150 mmol / L, and the oscillation temperature is 298±1K.

6. The method for separating thorium from natural thorium according to claim 3. 212 Pb / 212 The method of Bi is characterized by, In step 2), the organic solvent-based diluent is selected from one of 1,2-dichloroethane, nitrobenzene, kerosene, xylene, and n-octanol.

7. The method for separating thorium from natural thorium according to claim 3. 212 Pb / 212 The method of Bi is characterized by, In step 1), the lead-chlorine complex [PbCl3] is present in the aqueous production feed solution. - of 212 The Pb radioactivity ranges from 8.33 to 13.88 Bq, and the bismuth chloride complex [BiCl6] has a radioactivity of 8.33–13.88 Bq. 3- of 212 The radioactivity of Bi is 0.5~1.14 Bq.

8. The method for separating thorium from natural thorium according to claim 3 212 Pb / 212 The method of Bi is characterized by, The supported organic phase contains [PbCl3]. - [NR4] + Ionic compounds, [BiCl6] 3- [NR4]3 + Ionic compounds; in the aqueous production feed liquid, elements Th, La and Ba exist only in cationic or neutral forms, respectively.

9. The method for separating thorium from natural thorium according to claim 3. 212 Pb / 212 The method of Bi is characterized by, In step 3), the concentration of the hydrochloric acid solution used as the stripping agent is 1-6 mol / L, and the concentration of the perchloric acid solution used as the stripping agent is 1-3 mol / L.

10. The method for separating thorium from natural thorium according to claim 3. 212 Pb / 212 The method of Bi is characterized by, In step 3), the volume ratio of the added stripping agent to the volume of the supported organic phase is 1:1 during each stripping process.

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