Method for separating and extracting lead-212 and bismuth-212 from anion exchange fibers

Abstract

This invention belongs to the field of targeted α-nucleonite separation and extraction technology, specifically disclosing a method for separating and extracting lead-212 and bismuth-212 using anion exchange fibers. An acidic thorium solution is passed through an anion exchange fiber column, utilizing the fact that halogen anions can react with Pb. 2+ / Bi 2+ The formation of complex anions is selectively adsorbed by anion exchange fibers. A leaching agent is then introduced to remove other impurity ions. Finally, a desorption agent is introduced to desorb lead-212 and bismuth-212, thus achieving the separation and extraction of lead-212 and bismuth-212 from the natural thorium decay chain. This invention utilizes the above-described method for separating and extracting lead-212 and bismuth-212 using anion exchange fibers. This method eliminates the need for accelerators or reactors, and offers advantages such as simple equipment and the ability to simultaneously handle radioactive waste treatment and disposal while also enabling the separation and extraction of high-value-added targeted alpha nuclides.

Description

Technical Field

[0001] This invention relates to the field of targeted α-nuclein separation and extraction technology, and in particular to a method for separating and extracting lead-212 and bismuth-212 using anion exchange fibers. Background Technology

[0002] Ion exchange fibers (IEFs) possess numerous advantages, including large specific surface area, rapid exchange and elution rates, easy regeneration, high adsorption capacity, low fluid resistance, low filtration energy consumption, ease of fabrication into various shapes, diverse applications, and convenient use. Currently, ion exchange fibers are widely used in wastewater and waste gas purification, environmental protection, ion exchange, separation analysis, and the recovery of precious metals and other valuable substances.

[0003] Lead-212 and bismuth-212, as targeted alpha nuclides with significant clinical application value, have demonstrated remarkable efficacy and broad application prospects in targeted therapy of malignant tumors such as breast cancer, prostate cancer, and pancreatic cancer. Lead-212, in particular, has attracted considerable attention due to its near-ideal nuclear physics properties. Its 10.64-hour half-life ensures sufficient drug delivery time while achieving over 90% decay energy deposition at the tumor lesion. Although lead-212 itself is a beta-decaying nuclide, it can be effectively used for targeted alpha particle therapy through an in vivo 212Pb / 212Bi generator system, thus being recognized by the international academic community as an alpha therapeutic nuclide of equal importance to bismuth-212. Despite the significant advantages of these nuclides in precision oncology treatment, like other targeted alpha therapeutic nuclides, they have long faced a severe global supply-demand imbalance and industrialization bottleneck. The preparation of lead-212 typically relies on isolation from the decay daughter nuclei of thorium-228 or radium-224, and cannot be directly produced through cyclotron irradiation or nuclear reactor irradiation. Current production methods can only support part of the clinical research needs and are insufficient to meet the growing demand for targeted alpha nucleus drug development and future market demand.

[0004] Therefore, it is urgent to develop a simple, efficient, and low-cost method for the direct separation and extraction of lead-212 and bismuth-212 using anion exchange fibers. Summary of the Invention

[0005] The purpose of this invention is to provide a method for separating and extracting lead-212 and bismuth-212 using anion exchange fibers. This method utilizes anion exchange fibers to separate and extract lead-212 and bismuth-212 from natural thorium products, obtaining lead-212 and bismuth-212 without the need for an accelerator or reactor. It has the advantages of simple equipment, convenient operation, low cost, environmental friendliness, and the ability to simultaneously handle radioactive waste treatment and disposal as well as the separation and extraction of high-value-added targeted alpha nuclides.

[0006] To achieve the above objectives, the present invention provides a method for separating and extracting lead-212 and bismuth-212 using anion exchange fibers, comprising the following steps: Anion exchange fibers were fabricated into anion exchange fiber columns. An acidic natural thorium solution containing halide anions was prepared. The acidic thorium solution was then passed through the anion exchange fiber column, taking advantage of the fact that halide anions can react with Pb. 2+ / Bi 2+ The complex anions are formed and selectively adsorbed by anion exchange fibers. Then, a rinsing agent is introduced to wash away other impurity ions. Finally, a desorbing agent is introduced to desorb lead-212 and bismuth-212, thereby achieving the separation and extraction of lead-212 and bismuth-212 from the natural thorium decay chain.

[0007] Preferably, the anion exchange fiber includes a strong base fiber with quaternary amine or quaternary pyridyl groups as functional groups, or a weak base fiber with primary to tertiary amine or tertiary pyridyl groups as functional groups.

[0008] Preferably, the halide anion includes Cl. - ,Br - I - Its concentration is 0.1~5M.

[0009] Preferably, the natural thorium is a thorium product that is soluble in acid solutions and has a concentration of 0.1 M or higher.

[0010] Preferably, the operating pressure of the anion exchange fiber column is 0.1 MPa to 30 MPa, and the temperature is room temperature to 95°C.

[0011] Preferably, the rinsing agent is one or more of the following: HF, HCl, HBr, and HI, and its concentration is 0.1~3M.

[0012] Preferably, the desorbent is other than pure water or hydrohalic acid and does not react with Pb. 2+ / Bi 2+ An acidic solution that forms a complex anion has a concentration of 0-3 M.

[0013] The advantages and beneficial effects of the method for separating and extracting lead-212 and bismuth-212 using the above-mentioned anion exchange fiber are as follows: 1. The anion exchange fiber used in this invention has a fast adsorption / desorption rate, a strong structure and shape, and is suitable for use under high pressure and high flow rate conditions, which is beneficial for the rapid separation and extraction of Pb-212 / Bi-212 with a short half-life.

[0014] 2. This invention utilizes the selective reaction of halide ions with Pb 2+ / Bi 2+ [PbX4] is formed. 2- / [BiX4] 2-The selective adsorption of complex anions by anion exchange fibers enables targeted identification and separation of target elements in complex multi-metal systems.

[0015] 3. This application uses abundant natural thorium as raw material to directly separate and extract the high-value-added targeted alpha nuclides lead-212 and bismuth-212. This method does not require an accelerator or reactor, and features simple equipment, convenient operation, low cost, and relatively low requirements for radioactive safety protection. The method of this invention only extracts lead-212 and bismuth-212, without disrupting the long-term equilibrium between the daughter nuclides preceding radium-224 and the parent thorium-232. Therefore, the thorium source can be recycled indefinitely until thorium-232 completely decays.

[0016] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0017] Figure 1 (a) in the image is the FTIR image of the two types of anion exchange fibers, and (b) is the XRD image of the two types of anion exchange fibers. Figure 2 (a) and (b) in the image are SEM images of anion exchange fiber 2; Figure 3 (a) shows the adsorption of Pb and Bi by anion exchange fiber 1 in HBr solution; (b) shows the adsorption of Pb and Bi by anion exchange fiber 2 in HBr solution. Figure 4 (a) shows the interaction between fiber 2 and conventional anion exchange resin for Pb. 2+ (a) Comparison of adsorption rates; (b) shows the adsorption rates of fiber 2 and conventional anion exchange resin for Pb. 2+ Adsorption capacity comparison chart; Figure 5 (a) shows the adsorption of Pb and Bi by fiber 2 in hydrobromic acid, (b) shows the adsorption of Pb and Bi by fiber 2 in hydrochloric acid, and (c) shows the adsorption of Pb and Bi by fiber 2 in nitric acid. Figure 6 (a) shows the adsorption behavior of fiber 2 on Pb in 0.5MHBr solution, and (b) shows the adsorption behavior of fiber 2 on Bi in 0.5MHBr solution. Figure 7 The column experiment for separating Pb and Bi using fiber 2 was conducted, where I: dead volume; II: 100 ppm of mixed metal solution; III: 0.5 MHBr; IV: ultrapure water; V: 1 MHNO3, and the flow rate was 5 mL / min. Figure 8(a) is the high-purity germanium γ-ray energy spectrum of the thorium nitrate sample, and (b) is the high-purity germanium γ-ray energy spectrum of Pb-212 / Bi-212 in the Th-232 decay chain separated by fiber 2. Detailed Implementation

[0018] The technical solution of the present invention will be further described below with reference to the accompanying drawings and embodiments.

[0019] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0020] The following examples are not intended to limit the invention, but are only for illustration. Unless otherwise specified, the experimental methods used in the following examples are generally performed under conventional conditions. Unless otherwise specified, the materials and reagents used in the following examples are commercially available.

[0021] Example 1 A method for separating and extracting lead-212 and bismuth-212 using anion exchange fibers includes the following steps: Anion exchange fibers were fabricated into anion exchange fiber columns. An acidic natural thorium solution containing halide anions was prepared. The acidic thorium solution was then passed through the anion exchange fiber column, taking advantage of the fact that halide anions can react with Pb. 2+ / Bi 2+ Formation of complex anions ([PbX4)) 2- / [BiX4] 2- Lead-212 and bismuth-212 are selectively adsorbed by anion exchange fibers, while other nuclides (such as thorium-232, radium-228, actinium-228, etc.) pass directly through the anion exchange fiber column. Then, a rinsing agent is introduced to wash away other impurity ions. Finally, a desorbing agent is introduced to desorb lead-212 and bismuth-212, thereby achieving the separation and extraction of lead-212 and bismuth-212 in the natural thorium decay chain.

[0022] Anion exchange fibers include strong base fibers with quaternary amine or quaternary pyridyl groups as functional groups, or weak base fibers with primary to tertiary amine or tertiary pyridyl groups as functional groups.

[0023] Halogen anions include Cl - ,Br - I - Its concentration is 0.1~5M.

[0024] Natural thorium is a thorium product that is soluble in acid solutions (such as thorium nitrate, thorium oxide, thorium chloride, thorium-containing monazite and other minerals, etc.), with a concentration of 0.1 M or higher.

[0025] The operating pressure of the anion exchange fiber column is 0.1 MPa to 30 MPa, and the temperature is room temperature to 95℃.

[0026] The rinsing agent is one or a mixture of hydrohalic acids HF, HCl, HBr, and HI, with a concentration of 0.1~3M.

[0027] The desorbent is pure water or hydrohalic acid and does not react with Pb. 2+ / Bi 2+ Acidic solutions (nitric acid, sulfuric acid, perchloric acid) that form complex anions have a concentration of 0-3M (when the concentration is 0, they are desorbed with pure water).

[0028] Example 2 Characterization of anion exchange fibers: Anion exchange fibers include strong base fibers with quaternary amino groups or quaternary pyridyl groups as functional groups and weak base fibers with mono- to tertiary amino groups or tertiary pyridyl groups as functional groups, more preferably weak base fibers. Fiber 1 is rich in quaternary ammonium groups (-N). + (CH3)3) strong alkali fiber, fiber 2 is a weak alkali fiber rich in primary ammonium groups (-NH2).

[0029] The two types of anion exchange fibers were characterized by FTIR, XRD, and SEM, and the results are as follows: Figure 1 and Figure 2 As shown, it can be seen that: ① Fiber 1 contains -OH, -CH-, C=C, CN, -CH2, and CH functional groups, while the CH, -N=C=O, CO, and CN functional groups of fiber 2 have basically disappeared, leaving only the functional groups belonging to C=C, C=N, and -CH2; ② XRD patterns show that both fiber 1 and fiber 2 have amorphous structures; ③ SEM characterization results show that fiber 2 is a smooth, circular strip.

[0030] Example 3 Determination of the selective adsorption performance of two types of anion exchange fibers for Pb / Bi in HBr solution: Step 1: Prepare an HBr solution containing Th, La, Pb, Bi, and Ba, with each metal ion having a concentration of 100 ppm and the HBr concentration ranging from 0 to 5 M.

[0031] Step 2: Add 2 g / L of fiber 1 and fiber 2 to the mixed solution in step 1 respectively. After adsorption for 2 hours, take a 4 mL sample, filter it with a syringe filter, and save the liquid sample for testing.

[0032] Step 3: The concentrations of various metal ions in the water sample from Step 2 were detected by inductively coupled plasma atomic emission spectrometry, and the selective adsorption effects of different anion exchange fibers on Pb / Bi at different HBr concentrations were calculated.

[0033] The results are as follows Figure 3 As shown, fiber 1 exhibits good selective adsorption capacity for Pb and Bi in 0.5-2 MHBr solutions. However, for MHBr solutions of other acidities, the adsorption capacity of fiber 1 for Pb and Bi weakens, and it also adsorbs small amounts of impurity ions such as Th, La, and Ba. Fiber 2, on the other hand, demonstrates excellent adsorption performance for Pb and Bi in 0-5 MHBr solutions, but shows virtually no adsorption for Th, La, and Ba. These results indicate that fiber 2 has the potential to selectively separate and extract Pb-212 and bismuth-212 from the thorium-232 decay chain.

[0034] Example 4 Comparison of Pb adsorption performance between fiber 2 and conventional anion exchange resins (D301R, D202, 201×70H): Step 1: Prepare an HBr solution with a Pb concentration range of 0-1000 ppm and an acidity of 0.5 M.

[0035] Step 2: Add 2 g / L of fiber 2 or conventional anion exchange resin to the mixed solution in Step 1. Take a 4 mL sample at the set time gradient, filter it with a syringe filter, and save the liquid sample for testing.

[0036] Step 3: Detect the Pb ion concentration in the water sample from Step 2 using inductively coupled plasma atomic emission spectrometry (ICP-AES) and calculate the adsorption effect of different adsorbents on Pb.

[0037] The results are as follows Figure 4 As shown. By Figure 4 It can be seen that the adsorption rate of Pb by fiber 2 is much higher than that of conventional anion exchange resins D301R, D202, and 201×70H. Adsorption capacity studies revealed that the adsorption capacity of Pb by fiber 2 reaches 478.47 mg / g, while the adsorption capacity of commercial anion exchange resin D301R for Pb is only 162.02 mg / g. These results indicate that the separation efficiency of Pb by fiber 2 is far superior to that of conventional anion exchange resins.

[0038] Example 5 The adsorption effects of fiber 2 on Pb and Bi in different inorganic acids were determined: Step 1: Prepare a solution containing one of the following inorganic acids (HBr, HCl, or HNO3): Th, La, Pb, Bi, and Ba. The concentration of each metal ion is 100 ppm, and the concentration of the inorganic acid is in the range of 0-5 M.

[0039] Step 2: Add 2 g / L of fiber 2 to the mixed solution in Step 1. After adsorption for 2 hours, take a 4 mL sample, filter it with a syringe filter, and save the liquid sample for testing.

[0040] Step 3: Detect the concentration of each metal ion in the water sample from Step 2 using inductively coupled plasma atomic emission spectrometry, and calculate the adsorption effect of fiber 2 on Pb and Bi under different inorganic acids.

[0041] The results are as follows Figure 5 As shown, it can be seen that fiber 2 has a relatively ideal adsorption effect on Bi in HCl medium, while the adsorption effect on Pb is not significant; the adsorption effect of fiber 2 on Pb and Bi in HNO3 medium is very poor; however, fiber 2 exhibits the best selective adsorption capacity for Pb and Bi in HBr medium. These results indicate that HBr medium is most suitable for the selective separation of Pb-212 and Bi-212 in the Th-232 decay chain.

[0042] Example 6 Model for determining the adsorption isotherms of Pb and Bi on fiber 2: Step 1: Prepare an HBr solution with a Pb or Bi concentration of 300 ppm and an acidity of 0.5 M, and place the above mixed solution at 25°C. o C, 35 o C, 45 o In a constant temperature water bath of C.

[0043] Step 2: Add 2 g / L of fiber 2 to the mixed solution in Step 1. After adsorption for 2 hours, take a 4 mL sample, filter it with a syringe filter, and save the liquid sample for testing.

[0044] Step 3: Detect the concentrations of Pb and Bi ions in the water sample from Step 2 using inductively coupled plasma atomic emission spectrometry, and calculate the adsorption effect of fiber 2 on Pb and Bi at different temperatures.

[0045] The results are as follows Figure 6 As shown, it can be seen that: Figure 6 In Figure (a), the equilibrium adsorption capacity of Pb on the anion exchange fiber increases significantly with increasing equilibrium concentration of the solution, indicating that the fiber has a high adsorption capacity potential for Pb and that adsorption at room temperature (25°C) is achieved. o The optimal adsorption capacity is 325 mg / g at temperature C. Figure 6 Figure (b) shows that the adsorption isotherm of Bi on this anion exchange fiber exhibits typical Langmuir-type characteristics: at low equilibrium concentrations, the adsorption capacity increases rapidly with increasing concentration; when the equilibrium concentration exceeds approximately 100 mg / L, the rate of increase in adsorption capacity slows significantly, gradually stabilizing and approaching a saturation plateau, with the best adsorption at 35 °C, where the maximum adsorption capacity is 260 mg / g. These results indicate that fiber 2 exhibits rapid adsorption kinetics and high adsorption capacity for Pb and Bi. Furthermore, they demonstrate that the adsorption of Pb and Bi on this fiber conforms to a monolayer adsorption mechanism.

[0046] Example 7 Column experiments investigating the selective adsorption of Pb / Bi by fiber 2: Step 1: Take a number of fibers 2 and fill them into a glass adsorption column with a specification of Ф×h=5mm×100mm until it is full.

[0047] Step 2: Prepare a mixed HBr solution containing Th, La, Pb, Bi, and Ba, with each metal ion having a concentration of 100 ppm and the HBr concentration being 0.5 M.

[0048] Step 3: Adopt the bottom-up flow mode, first pass ultrapure water at 1 mL / min to remove air bubbles, and then pass 50 mL of 0.5 MHBr solution to pretreat the anion exchange fiber column.

[0049] Step 4: Pass the mixed solution from Step 2 into the anion exchange fiber column at a flow rate of 5 mL / min. At this point, Pb and Bi are simultaneously adsorbed onto the fiber column until it is completely saturated, while Th, La, Ba, etc., cannot be adsorbed by the anion exchange fiber column and flow out with the effluent. After the anion exchange fiber column is saturated, ultrapure water and 1 M HNO3 are passed through at a flow rate of 1 mL / min for the desorption of Pb and Bi, respectively.

[0050] The results are as follows Figure 7 As shown, Pb and Bi ions can be completely adsorbed by fiber 2, while Th, La, and Ba ions cannot be adsorbed by fiber 2 and flow out with the effluent. Furthermore, the introduction of ultrapure water allows for selective desorption of Pb, and the introduction of 1M HNO3 allows for selective desorption of Bi. These results indicate that fiber 2 can not only achieve the separation of Pb / Bi in the Th-232 decay chain but also the mutual separation of Pb and Bi.

[0051] Example 8 Experimental Investigation of Hot Separation of Pb-212 and Bi-212: Step 1: Prepare 250 mL of 0.83 M thorium nitrate solution, and then filter the thorium nitrate solution once using a sand core filter to obtain a thorium nitrate solution without precipitates.

[0052] Step 2: The column parameters are designed as follows: H×Φ=100mm×7.8mm, V=4.78cm 3 The mass of the filling fiber 2 is m = 2.39 g, and the bulk density is ρ = 0.5 g / cm³. 3 The flow rate was 30 mL / min.

[0053] Step 3: Take 50 mL of UP water (ultrapure water), start the pump and pass the UP water into the column at 10 mL / min to purge air. Then, pass 120 mL of 0.5 MHBr solution for pretreatment. Set the pump flow rate to 10 mL / min. After the MHBr solution has completely passed through the column, pass the thorium nitrate solution from Step 1 at a flow rate of 5 mL / min and record the start time. Then, use a high-purity germanium gamma spectrometer to test the count values ​​of the influent and effluent.

[0054] Step 4: After the thorium nitrate solution has completely passed through the column, 300 mL of 0.5 MBr solution (elution agent, equivalent to 60 column volumes) is introduced at a elution rate of 10 mL / min. Six column volumes are collected as one fraction, and the Th concentration in the eluent is measured subsequently.

[0055] Step 5: After collecting 60 column volumes of eluent, UP water (ultrapure water) / HNO3 was introduced to desorb Pb-212 and Bi-212 at a flow rate of 10 mL / min. 60 column volumes were collected, and the count was measured using a high-purity germanium gamma spectrometer. The column volume was recorded when the count disappeared.

[0056] The results are as follows Figure 8 As shown, the original thorium nitrate feed solution contained multiple nuclides such as Ac(a)-228, Ra(lei)-224, Pb-212, and Bi-212. However, after adsorption by fiber 2, elution with HBr, and desorption with UP water / HNO3, the resulting desorbate contained only Pb-212, Bi-212, and Pb / Bi decay products. Furthermore, the removal rate of Pb / Bi exceeded 60%, and the recovery rate exceeded 50%. This result indicates that fiber 2 can be directly used for the selective separation of Pb-212 and Bi-212 in the Th-232 decay chain.

[0057] Therefore, this invention employs the above-mentioned method for separating and extracting lead-212 and bismuth-212 using anion exchange fibers. Anion exchange fibers possess rapid adsorption / desorption rates, robust structure and shape, making them suitable for use under high pressure and high flow rate conditions. This facilitates the rapid separation and extraction of Pb-212 / Bi-212, which have relatively short half-lives, utilizing halide ions (X). - ) can be selectively combined with Pb 2 + / Bi 2+ [PbX4] is formed. 2- / [BiX4] 2- The selective adsorption of complex anions by anion exchange fibers enables targeted identification and separation of target elements in complex multi-metal systems.

[0058] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for separating and extracting lead-212 and bismuth-212 using anion exchange fibers, characterized in that, Includes the following steps: Anion exchange fibers were fabricated into anion exchange fiber columns. An acidic natural thorium solution containing halide anions was prepared. The acidic thorium solution was then passed through the anion exchange fiber column, utilizing the reaction between halide anions and Pb. 2+ / Bi 2+ The complex anions are formed and selectively adsorbed by the anion exchange fiber. Then, the rinsing agent is passed through to wash away other impurity ions. Finally, the desorbing agent is passed through to desorb lead-212 and bismuth-212, thereby achieving the separation and extraction of lead-212 and bismuth-212 in the natural thorium decay chain. Anion exchange fibers include strong base fibers with quaternary amine groups or quaternary pyridyl groups as functional groups, or weak base fibers with primary to tertiary amine groups or tertiary pyridyl groups as functional groups. Halogen anions include Cl - ,Br - I - Strong base fibers with quaternary amino or quaternary pyridyl groups as functional groups have a halide anion concentration of 0.5~2M; weak base fibers with primary to tertiary amino or tertiary pyridyl groups as functional groups have a halide anion concentration of 0.1~5M.

2. The method for separating and extracting lead-212 and bismuth-212 using anion exchange fibers according to claim 1, characterized in that: Natural thorium is a thorium product that is soluble in acid solutions, with a concentration of 0.1 M or higher.

3. The method for separating and extracting lead-212 and bismuth-212 using anion exchange fibers according to claim 1, characterized in that: The operating pressure of the anion exchange fiber column is 0.1MPa~30MPa, and the temperature is 25℃~95℃.

4. The method for separating and extracting lead-212 and bismuth-212 using anion exchange fibers according to claim 1, characterized in that: The rinsing agent is one or more of the following: hydrohalic acids HF, HCl, HBr, and HI, and the concentration is 0.1~3M.

5. The method for separating and extracting lead-212 and bismuth-212 using anion exchange fibers according to claim 1, characterized in that: The desorbent is pure water or hydrohalic acid and does not react with Pb. 2+ / Bi 2+ An acidic solution that forms a complex anion has a concentration of 0-3 M.

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