A type of radioactivity 239 Methods and applications of Pu separation

Abstract

This invention provides a radioactive 239 A method for separating Pu and its application, wherein the separation method uses a macroporous resin composite material of o-phenanthroline phosphonate to separate Pu from marine biological samples. 239 Pu is used for enrichment and separation. The o-phenanthroline phosphonate macroporous resin composite material consists of a solid support material and o-phenanthroline phosphonate ligands loaded thereon. This invention uses this novel resin as the core adsorbent material to achieve enrichment and separation of marine biological samples. 239 Highly efficient enrichment of Pu, and also through the use of novel elution reagent combinations, for loaded with 239 The macroporous resin composite of phenanthroline phosphonate with Pu and other interfering elements was rinsed to complete the process. 239 Effective separation of Pu from interfering elements.

Description

Technical Field

[0001] This invention relates to the technical field of radionuclide separation, and in particular to a radioactive nuclide separation method. 239 Methods and applications of Pu separation. Background Technology

[0002] 239 Pu (plutonium-239), as an alpha radionuclide, has a relatively long half-life (2.41 × 10⁻⁶). 4 (Year), and exhibits strong toxicity. Currently present in the marine environment 239 Pu primarily originates from historical atmospheric nuclear tests, nuclear power plant accidents, and liquid emissions from spent fuel reprocessing facilities. Due to its strong particle affinity, plutonium remains in the marine environment for a long time and is easily adsorbed and absorbed by marine organisms. This leads to biomigration and bioaccumulation through the food chain, posing a long-term potential risk to the marine ecosystem.

[0003] Human intake from seafood 239 Pu (Pu) tends to deposit in the liver and bone tissue, potentially causing cell damage and genetic abnormalities, and increasing the risk of cancer. Although the risk is usually negligible at background levels, the risks of accidents and unconventional emissions are difficult to completely eliminate given the rapid development of nuclear energy and the full life-cycle operation of nuclear facilities. Once plutonium enters the ocean, it can migrate through waterways and be ingested by organisms, accumulating in seafood and posing food safety and public health risks. Therefore, there is an urgent need to develop a system that is both highly sensitive and highly resistant to interference, designed for the complex matrix of marine organisms. 239 Pu analysis methods are used to support radiation safety assessments and related risk management of seafood.

[0004] Methods for measuring plutonium in environmental media are mainly divided into radiochemical methods and mass spectrometry, depending on the different instrument measurement principles. Because... 239 Pu has a long decay period, and its low specific activity limits the sensitivity and detection efficiency of radiometric measurement techniques such as alpha spectroscopy. In contrast, mass spectrometry, especially inductively coupled plasma mass spectrometry (ICP-MS), offers advantages in... 239 Pu has significant advantages in detection; however, ICP-MS measurements are limited by polyatomic ion compounds (P2P). 238 UH + The effects of these compounds will... 239 Pu exhibits signal overlap at the same mass-to-charge ratio (m / z=239). Previous studies have reported that elements such as U, Pb, and Bi may be helpful for ultra-trace element determination by ICP-MS. 239 Pu generates polyatomic ion interferences, which must be removed before measurement. It is worth noting that... 238 U is abundant in the natural environment, and 238UH + The generation rate is high in ICP-MS.

[0005] To eliminate IEs and enable ICP-MS to analyze samples... 239 To accurately determine plutonium (Pu), researchers have reported various chemical separation strategies: liquid-liquid extraction, ion exchange chromatography, and extraction chromatography. Liquid-liquid extraction was the earliest method applied to the separation of plutonium from environmental and radioactive samples; however, as a solvent extraction process, it has significant drawbacks, generating organic liquid waste and radioactive liquid waste. In contrast, extraction resin methods are increasingly favored in practical applications due to their faster exchange kinetics, lower acid consumption, and less hazardous waste generation. The principle of extraction resins is to chemically bond or physically adsorb a selective extractant onto an inert solid support, thereby forming a unique stationary phase. Examples include TRU, TEVA resin, and TK200 resin. These resin technologies are used in… 239 Pu plays a crucial role in the analysis and removal of interferences. Existing techniques report the use of anion exchange chromatography coupled with TEVA extraction chromatography to remove interferences. 238 U, experimental results show that the average uranium removal factor can exceed 10. 3 Other reports indicate that a single-column TK200 extraction resin system achieved a uranium removal efficiency of 10%. 4 Magnitude.

[0006] While existing commercial extraction resins have demonstrated excellent performance in plutonium separation, their application still has certain limitations. These resins require loading into a nitric acid medium of a specific concentration to achieve optimal plutonium adsorption. Furthermore, the presence of abundant Na, K, and Ca elements in marine biological samples can affect plutonium adsorption behavior on the resin, thereby reducing plutonium recovery rates. Additionally, considering the presence of... 239 The Pu content is significantly lower than that in soil and sediment, thus requiring larger sample volumes for analysis. However, as the sample volume increases, the amount of ash produced during the ashing process also increases, and even with the use of large amounts of anti-aqua regia and extended digestion time, a certain amount of residue will still remain. Conventional experimental methods typically use filtration to collect the ash. 239 While the acid leaching extract from Pu is effective, this method presents a significant challenge in processing the residue remaining after digestion of large quantities of marine biological samples. This residue readily coats the surface of filter paper or cartridges during filtration, leading to a substantial decrease in filtration efficiency (more than one day). Even with vacuum filtration devices, complete filtration still requires several hours, which is not only time-consuming but also increases the risk of equipment wear and tear due to prolonged operation. Summary of the Invention

[0007] The purpose of this invention is to provide a radioactive 239This invention relates to a method for separating Pu, aiming to address the problems existing in the prior art and achieve the separation of Pu from marine biological samples. 239 The efficient enrichment of Pu was completed simultaneously 239 Effective separation of Pu from interfering elements.

[0008] To achieve the above objectives, the present invention provides the following solution:

[0009] The first aspect of the present invention provides a radioactive 239 A method for separating Pu, wherein the separation method employs a macroporous resin composite material of o-phenanthroline phosphonate for the separation of Pu from marine biological samples. 239 Pu is used for enrichment and separation. The o-phenanthroline phosphonate macroporous resin composite material consists of a solid support material and o-phenanthroline phosphonate ligands loaded thereon. The structural formula of the o-phenanthroline phosphonate ligands is as follows:

[0010]

[0011] The main reason for using o-phenanthroline phosphonate macroporous resin composites is: Pu 4+ It coordinates with the N and O in the ligand structure, and each ligand structure interacts with only one Pu. 4+ In the binding process, the substituents containing P=O bonds in the ligand are key coordination sites, Pu 4+ The longer the bond length between the atom and the N or O atom, the stronger its coordination ability.

[0012] Preferably, the method includes:

[0013] S1. After collecting marine biological samples, ashing and acid digestion were performed. The supernatant was collected by centrifugation, and then enriched and purified to obtain the product containing... 239 Pu's sample solution;

[0014] S2, prepare o-phenanthroline phosphonate ligand by dissolving the o-phenanthroline phosphonate ligand in an organic solvent, then adding the pretreated solid support material, stirring and mixing, and drying to obtain the o-phenanthroline phosphonate macroporous resin composite material. The mass ratio of the o-phenanthroline phosphonate ligand to the solid support material is 1:2-4, preferably 1:3.

[0015] S3, the o-phenanthroline phosphonate macroporous resin composite material is activated with nitric acid, containing... 239 A sample solution of Pu was injected into the activated o-phenanthroline phosphonate macroporous resin composite material. The o-phenanthroline phosphonate macroporous resin composite material was then repeatedly eluted with eluent to obtain a solution containing Pu. 239 The eluent for Pu, the first eluent comprising nitric acid solution and hydrochloric acid solution, and the second eluent being a mixed solution containing oxalic acid compounds and a reducing agent.

[0016] Preferably, the concentration of hydrochloric acid solution in the first eluent is 7-9 M, more preferably 8 M.

[0017] Preferably, the concentration of nitric acid solution in the first eluent is 4-6 M, more preferably 5 M.

[0018] Preferably, in the second eluent, the concentration ratio of the oxalic acid compound to the reducing agent is 1:0.8-1.2, more preferably 1:1, wherein the oxalic acid compound includes oxalic acid, and the reducing agent includes hydroxylamine hydrochloride.

[0019] Preferably, in step S3, the o-phenanthroline phosphonate macroporous resin composite material is activated with nitric acid, and the activation concentration of nitric acid is 0.1-8 M.

[0020] Preferably, in S2, the preparation of the o-phenanthroline phosphonate ligand includes:

[0021] 2,9-Dichloro-1,10-phenanthroline and bis(2-ethylhexyl)phosphonite were added to a mixed solution and refluxed. The mixture was then filtered and rotary evaporated to obtain an oily crude product. The crude product was purified by silica gel column chromatography to obtain o-phenanthroline phosphonate ligand.

[0022] The mixed solution comprises palladium acetate, 1,1'-bis(diphenylphosphine)ferrocene, triethylamine, and anhydrous toluene.

[0023] Preferably, the molar ratio of the 2,9-dichloro-1,10-phenanthroline and the bis(2-ethylhexyl)phosphonite is 1:2 to 1:3.

[0024] Preferably, the molar ratio of palladium acetate to 1,1'-bis(diphenylphosphine)ferrocene is 1:2.

[0025] In S1, the centrifugation speed is 4200-4600 rpm and the centrifugation time is 8-12 min.

[0026] Preferably, the solid support material is selected from porous resins, including XAD-7 resin and / or XAD-6 resin.

[0027] A second aspect of the present invention provides a radioactive material as described above. 239 Pu separation methods in ultra-trace samples of marine organisms 239 Applications in Pu analysis.

[0028] This invention discloses the following technical effects: This invention provides a radioactive 239 A method and application for the separation of Pu, which uses o-phenanthroline phosphonate macroporous resin composite material for the separation of Pu in marine biological samples. 239Pu was used for separation. This o-phenanthroline phosphonate macroporous resin composite material consists of a solid support material and o-phenanthroline phosphonate ligands loaded on it. This invention uses this novel resin as the core adsorption material to achieve separation of marine biological samples. 239 Highly efficient enrichment of Pu for trace amounts in marine biological samples 239 Pu exhibits excellent enrichment capabilities, with an enrichment efficiency exceeding 99.9%. Furthermore, this invention utilizes centrifugation to collect the enriched product from acid digestion of large-volume samples. 239 The PU digestion solution significantly improves overall analytical efficiency by reducing unnecessary time consumption in traditional processing. Furthermore, a novel elution reagent combination was used to elute the o-phenanthroline phosphonate macroporous resin composite material, completing the process. 239 Effective separation of Pu from interfering elements. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of the synthesis process of the o-phenanthroline phosphonate ligand in Example 1 of the present invention;

[0031] Figure 2 This invention relates to the effects of EtHex-POPhen / XAD-7 resin in Example 1 of the present invention on different concentrations of nitric acid in a high matrix environment. 239 Pu adsorption efficiency diagram;

[0032] Figure 3 This is a comparison diagram of the chemical behavior of interfering elements on EtHex-POPhen / XAD-7 resin columns using solutions of different acidities in this invention;

[0033] Figure 4 The elution solution used in this invention is for... 239 A diagram illustrating the elution efficiency of Pu;

[0034] Figure 5 This is a comparison of the results of marine biological samples from this invention under different treatment methods.

[0035] Figure 6 This invention relates to different resin pairs in high matrix environments. 239 Comparison chart of Pu adsorption efficiency;

[0036] Figure 7 For marine organisms in Example 1 of the present invention 239PU analysis flowchart. Detailed Implementation

[0037] Various exemplary embodiments of the present invention are now described in detail. This detailed description should not be considered as a limitation of the invention, but rather as a more detailed description of certain aspects, features, and embodiments of the invention. Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of the invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with those documents. In the event of any conflict with any incorporated document, the content of this specification shall prevail. Various modifications and variations may be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0038] The radioactivity provided by this invention 239 Pu separation methods and applications; for detailed steps, please refer to [reference needed]. Figure 7 All reagents used in this invention are commercially available products, and all marine biological samples used in this invention are purchased from the market.

[0039] Example 1

[0040] (1) Processing of marine biological samples

[0041] This invention selects ash from marine fish samples, and the operation steps are as follows: add 100 pg 239Pu was used as a tracer, and a prepared aqua regia solution (HCl:HNO3 = 1:3) was slowly added. The mass-to-volume ratio of the sample to the aqua regia solution was 1:10 g / ml. After the carbonates decomposed, FeCl3 was added to mask the interference of biogenic phosphorus. The mixture was then heated on a hot plate at 200 °C for 3 h. After cooling, the mixture was transferred to a centrifuge tube and centrifuged at 4500 rpm for 10 min. The supernatant was collected, and the residue in the centrifuge tube was washed with 10 mL of 0.5 M HNO3. The mixture was then centrifuged again, and the supernatants were combined. Add 100 mL of deionized water and 10 mg of Fe(III) to the supernatant, slowly add concentrated NH4OH while stirring constantly, and adjust the pH to 8-9 until Fe(OH)3-Pu(OH)4-Ca3(PO4)2 precipitate is formed; transfer the precipitate sample to a centrifuge tube and centrifuge at 4500 rpm for 10 min, discarding the supernatant; successively use 2 M NaOH (to wash away amphoteric elements such as aluminum, vanadium, and zinc) and ultrapure water (to wash away residual NaOH from the previous washing step to wash the precipitate), centrifuging at 4500 rpm for 10 min, discarding the supernatant; dissolve the precipitate with about 10 mL of concentrated HCl, and add 2.0 g of K2S2O5 to reduce the target element to a low valence state (Pu). 3+ Dilute the sample solution with ultrapure water to approximately 100 mL, slowly add concentrated NH4OH while stirring continuously, adjust the pH to 8-9, and co-precipitate again; transfer the sample to a centrifuge tube, centrifuge at 4500 rpm for 10 min, and discard the supernatant; add 20 mL of 8 M MHNO3 to dissolve the precipitate; add 2 mL of 1 M NaNO2 to remove Pu from the solution. 3+ Oxidation to Pu 4+ Mix thoroughly, let stand for 30 minutes, and obtain the product containing... 239 The sample solution of Pu was prepared for passing through a resin column.

[0042] (2) Preparation of o-phenanthroline phosphonate ligand (EtHex-POPhen)

[0043] Using 2,9-dichloro-1,10-phenanthroline and bis(2-ethylhexyl) phosphite as raw materials, the preparation process is as follows: 2,9-dichloro-1,10-phenanthroline (2.0 g, 8.0 mmol) and bis(2-ethylhexyl) phosphite (3.9 g, 20.0 mmol) were dissolved in a mixture containing palladium acetate (Pd(OAc)2 (91 mg, 0.4 mmol)), 1,1'-bis(diphenylphosphine)ferrocene (DPPF (445 mg, 0.8 mmol)), triethylamine (1.5 mL), and anhydrous toluene (80.0 mL). The mixture was refluxed at 110 °C for 24 hours under argon protection. After removing the solvent by rotary evaporation, the mixture was further purified by silica gel column chromatography (dichloromethane / ethyl acetate / methanol, volume ratio 20:20:1) to obtain a white solid, EtHex-POPhen. The specific synthesis process is detailed in [link to details]. Figure 1 The yield using this method was 2.0 g, with a yield of 44%. The specific steps for preparing the o-phenanthroline phosphonate ligand are as follows:

[0044] Weigh the required reactants 2,9-dichloro-1,10-phenanthroline, bis(2-ethylhexyl) phosphite, palladium acetate catalyst, and DPPF into a 125 mL three-necked flask according to the above proportions. Add a magnetic stir bar, then use the Schlenk technique to purge the air and introduce high-purity argon to achieve the required oxygen-free conditions for the reaction. The Schlenk technique involves connecting the three-necked flask to a double-row tube, using a vacuum pump to evacuate the system for 15-20 seconds to purge the air, then introducing argon gas through the argon cylinder, and then evacuating the system again for 15-20 seconds. Repeat this cycle 5 times to ensure the system is completely purged of air and replaced with argon. Inject 80.0 mL of ultra-dry toluene and 1.5 mL of triethylamine (to neutralize the hydrochloric acid generated in the reaction and promote the forward reaction) through a syringe. Turn on the magnetic stirrer and set the temperature to 110 °C (110 °C is the boiling point of the solvent toluene). Initially, the reaction system was yellow. After 3 hours, the color gradually deepened to a deep purplish-red. The amount of solvent in the flask was monitored, and a small amount of ultra-dry toluene was added as needed (unreacted reactants and products may adhere to the inner wall of the flask above the liquid surface; these should be rinsed clean with solvent). Every 3 hours, a small amount of the reaction solution was aspirated using a syringe and spotted onto a TLC plate to monitor the reaction progress. The complete consumption of reactants was determined by comparing the development of the reactants and the reaction solution on the TLC plate. To obtain a higher yield, the reaction was refluxed for 24 hours. The reaction solution was then collected for purification and separation. The system at the end of the reaction was observed to be brown.

[0045] The separation and purification steps were as follows: The inner wall of the lower beaker was rinsed with dichloromethane to remove residual solids and viscous substances. The washings were added to the reaction solution, and the mixture was rotary evaporated to remove dichloromethane and toluene. To remove water-soluble impurities, an appropriate amount of deionized water and dichloromethane were added and stirred well. The mixture was allowed to stand and separated, leaving the oil phase. A small amount of dichloromethane was added to the aqueous phase, and the mixture was allowed to stand and separated again. The two oil phases were combined. To remove residual water from the oil phase, anhydrous Na₂SO₄ powder was added while stirring. After standing for 10 minutes, the mixture was filtered. The resulting organic liquid was rotary evaporated to remove the solvent dichloromethane, yielding crude EtHex-POPhen. The product was further purified by silica gel column chromatography. The selected eluent volume ratio was dichloromethane:ethyl acetate:methanol = 20:20:1. Column purification yielded a relatively pure white solid, EtHex-POPhen.

[0046] (3) Preparation of o-phenanthroline phosphonate resin composite material (EtHex-POPhen / XAD-7)

[0047] XAD-7 was activated with acetone (1.5 g XAD-7, 4.0 mL acetone) and repeated three times to remove residual solvent and impurities from the pores of the XAD-7 resin. The activated XAD-7 support was dried overnight in a vacuum oven at 85 °C to obtain a white powder product.

[0048] EtHex-POPhen / XAD-7 was prepared by directly loading EtHex-POPhen into the macropores of an XAD-7 support using a physical vacuum impregnation method. The specific preparation process is as follows: 0.5 g of EtHex-POPhen was dissolved in 40.0 mL of dichloromethane, and 1.5 g of activated and dried XAD-7 was added under stirring. The resulting suspension was stirred in a rotary evaporator at room temperature and atmospheric pressure for two hours to ensure that the ligand molecules were fully and uniformly dispersed on the surface of the XAD-7 support. Subsequently, the solvent was slowly removed at 45 °C under reduced pressure, allowing the two ligand molecules to penetrate and immobilize in the pores of the XAD-7 particles through capillary action and intermolecular interactions. Finally, the mixture was dried overnight in a vacuum oven at 60 °C to obtain the final o-phenanthroline phosphonate resin composite material (EtHex-POPhen / XAD-7).

[0049] (4) EtHex-POPhen / XAD-7 resin in complex matrices 239 Adsorption and separation of Pu

[0050] Due to the complex matrix of marine biological samples, after ashing and acid leaching, in addition to the target radionuclide Pu, a large number of coexisting elements, including K and Ca, will also be efficiently leached, forming a complex analytical system with high salinity and multiple components. The matrix elements of the marine biological samples in step (1) include Ca, Na, K, and Mg (all at a concentration of 1 μg / mL), and the concentration of Pu is 1 pg / mL. The adsorption experiment was performed as follows: EtHex-POPhen / XAD-7 was pretreated with 10 mL of 8 M HNO3, and the sample containing... 239 The Pu sample solution was injected into the activated o-phenanthroline phosphonate macroporous resin composite. The first elution was performed sequentially with 20 mL of 5 M HNO3 solution and 20 mL of 8 M HCl solution to remove interfering elements such as Hg, Pb, Bi, and Tl. Finally, the sample solution from the o-phenanthroline phosphonate macroporous resin composite was removed. 239 Pu was eluted with 30 mL of a mixed eluent containing 0.1 M H₂C₂O₄ and 0.1 M NH₂OH·HCl into a 100 mL PTFE (polytetrafluoroethylene) beaker to obtain a solution containing... 239 The eluent of Pu was then added to 10 mL of concentrated nitric acid to remove H2C2O4 and 0.1 M NH2OH・HCl. The mixture was heated to evaporate at 200 °C and then diluted to 10 mL with 5% nitric acid solution for ICP-MS analysis.

[0051] In addition, based on the above experiments, this invention investigated the effect of different concentrations of nitric acid pretreatment on the adsorption performance of EtHex-POPhen / XAD-7 resin, and the results are shown in [Figure number missing]. Figure 2 Even in complex systems containing high concentrations of matrix elements, the EtHex-POPhen / XAD-7 resin exhibits excellent selectivity and stability for trace amounts of Pu. Furthermore, when the solution acidity varies within the range of 0.1–8 M HNO3, the adsorption rate for trace Pu consistently exceeds 99.9%, indicating that its coordination sites possess extremely strong specific affinity for Pu, and the EtHex-POPhen ligands maintain structural stability across a wide acidity range. This characteristic makes it suitable for ultra-trace enrichment of Pu in biological samples.

[0052] In addition, based on the above experiments, this invention also studied the effect of different eluents on the Pu separation results, as follows:

[0053] Determination of the first eluent: The elution efficiency of HNO3, HCl, oxalic acid, and HF at various acidities was studied through elution experiments (only the type and concentration of the first eluent were changed, while all other conditions remained the same) to remove interferons (IEs) from EtHex-POPhen / XAD-7 resin. The IEs were U, Hg, Pb, Bi, and Tl. The elution experiments were conducted as follows: 1) EtHex-POPhen / XAD-7 resin was pretreated with 10 mL of the acid solution to be tested; 2) 1 mL of 1 μg / mL standard solutions of U, Hg, Pb, Bi, and Tl were taken respectively, and the solution was diluted to 100 mL with the acid solution of the tested concentration to obtain a 10 ng / mL spiked acid solution. 1) Add 10 mL of spiked acid solution (10 ng / mL for each element) to the EtHex-POPhen / XAD-7 resin column; 2) Rinse with another 10 mL of the acid solution of the measured concentration; 3) Collect the solutions from steps 2 and 3 for ICP-MS measurement. The test molar concentrations of HNO3 and HCl were 0.1 M, 1 M, 3 M, 5 M, and 8 M, respectively. The test molar concentrations of HF and oxalic acid were 0.01 M, 0.05 M, 0.1 M, and 0.5 M, respectively. The elution results are as follows: Figure 3 As shown, the y-axis represents the portion of IEs eluted during sample loading and subsequent washing steps. Figure 3 In the figure, a and b represent the chemical behaviors of various interfering elements on the EtHex-POPhen / XAD-7 resin column in nitric acid and hydrochloric acid media, respectively; c and d represent the chemical behaviors of the important interfering element U on the EtHex-POPhen / XAD-7 resin column under HF and H2C2O4 conditions, respectively. In HCl medium, Tl exhibits a strong retention capacity on the resin ( Figure 3 (b) in the text, while in 0.1-8 M HNO3 medium it only exhibits weak retention characteristics ( Figure 3 (a) Pb and Bi exhibit similar chemical behaviors on resins, and the resins demonstrate a strong ability to retain Pb and Bi in HNO3 media. Figure 3 (a) In HCl medium, both IEs are eluted by high concentrations of HCl as the HCl concentration increases, with Pb showing better elution efficiency than Bi. Figure 3 (b) Regarding Hg, the resin's retention capacity decreases under high-concentration acidic conditions, especially in nitric acid media. Effective elution of most Hg can be achieved when the nitric acid concentration exceeds 5 M. Figure 3 (a) Finally, in hydrochloric acid and nitric acid media, U exhibits extremely strong retention on EtHex-POPhen / XAD-7 resin, with its retention behavior being minimally affected by acidity; only a small amount is eluted under 8M hydrochloric acid conditions. Figure 3(a, b in the original text). Furthermore, this invention also investigated the retention behavior of U on the resin in an acidic medium with complexing activity (…). Figure 3 (c, d in the original text). The results showed that 0.5 M HF could elute a small amount of U, but in oxalic acid medium, U was stably retained by the resin.

[0054] Based on the above experimental results, the present invention preferably uses 5 M nitric acid and 8 M hydrochloric acid as the first eluent. During elution, nitric acid is used first, followed by hydrochloric acid, in that order to elute Tl, Hg, Bi, and Pb.

[0055] Determination of the second eluent: When eluting target elements from o-phenanthroline phosphonate macroporous resin composites, traditional techniques mainly rely on the strong chelating effect of ethylenediaminetetraacetic acid (EDTA). However, the non-selective chelating properties of EDTA for metal ions lead to the simultaneous elution of interfering elements such as U, significantly reducing the selective separation efficiency of Pu. This limitation is particularly prominent in ultra-trace Pu analysis, where even small amounts of co-eluting of U can severely interfere with subsequent mass spectrometry detection. Based on previous research and experience in separating Pu using commercial resins, this study investigated the elution efficiency of different concentrations of HCl and HF, as well as the effect of adding a reducing agent on the elution effect (see Table 1). The experiment only changed the type and concentration of the second eluent; all other conditions were the same as in steps 1-4 of the examples. The results showed that neither low nor high concentrations of HCl could elute Pu adsorbed by the EtHex-POPhen / XAD-7 resin, and the introduction of the reducing agent did not improve the elution results. Without the reducing agent, HF also failed to effectively elute Pu. When 0.1 M NH2OH·HCl was added as a reducing agent, the elution rate of Pu by the 0.1 M HF solution reached approximately 10%, which was a slight improvement, but the elution effect was still unsatisfactory. This invention uses oxalic acid as the eluent. Research results show that 0.1 M and 0.5 M oxalic acid solutions achieved elution rates of 31.3% and 41.8% for Pu in the resin, respectively. Oxalic acid is known to have reducing and complexing properties, and its effectiveness in eluting Pu in resins is significant when using only oxalic acid as the eluent. 239 The elution efficiency of Pu was relatively low; however, after adding the special reducing agent NH2OH·HCl, the elution efficiency of Pu by both concentrations of oxalic acid solution was significantly improved to over 97%, achieving almost complete stripping of Pu from the resin, which proves that the oxalic acid-reducing agent combination has excellent elution performance.

[0056] Table 1 Screening of the second eluent

[0057]

[0058] Elution curves of Pu (using Pu standard solution as the research object) in resin using a mixed solution of 0.1 M H₂C₂O₄ and 0.1 M NH₂OH·HCl showed that when the eluent consumption reached 30 mL, a Pu elution rate of over 95% could be achieved. Further increasing the eluent volume did not significantly improve the elution effect. (See attached results.) Figure 4 .

[0059] Comparative Example 1 (Marine biological samples were processed using a filtration method)

[0060] The ash content of the marine fish sample from Example 1 was selected, and 100 pg was added. 239 Pu is used as a tracer, in addition to collecting samples containing [unclear text - possibly a substance or ingredient] by filtration. 239 The Pu extract underwent the same processing steps as in Example 1, and the final analysis was performed by ICP-MS to observe the differences between the two methods. 239 Differences in losses during the Pu recycling process. For example... Figure 5 As shown in Figure a, after the ash obtained from the ashing of 1 kg of marine fish sample was digested with anti-aqua regia at 200 °C for 3 h, the solution still failed to reach the ideal clear and transparent state. Filtration was used to separate the contents... 239 Pu extract (when) Figure 5 (b) The fine particles and high content of the digestion residue easily form a dense coating on the filter element surface, causing the filter layer to clog rapidly, thus significantly reducing the filtration throughput and prolonging the processing time. Figure 5 In this text, 'c' represents the digestion product collected in centrifuge tubes, and 'd' represents the product obtained after centrifugation containing... 239 Compared to the Pu leachate, centrifugation as described in Example 1 can achieve solid-liquid separation more efficiently and obtain a solution containing […]. 239 Pu leachate. Recovery rate assessment results indicate that when collecting the leachate by centrifugation... 239 The recovery rate of Pu was 85.1% (n=3), which was not significantly different from that of the filtration method (81.6%). The results are shown in Table 2, indicating that the centrifugation step does not cause any damage. 239 Additional loss of Pu. A comprehensive comparison of the two treatment methods reveals that, assuming no significant difference in recovery rate, centrifugation offers clear advantages in processing efficiency, ease of operation, and reduced manpower, making it more suitable for pretreatment of large volumes of marine biological samples.

[0061] Table 2 Results of the Examples and Comparative Examples

[0062]

[0063] Comparative Example 2 (replacing EtHex-POPhen / XAD-7 resin)

[0064] Among existing commercial resins, TRU resin uses octylphenyl-N,N-diisobutylcarbamoylphosphine (CMPO) as its core functional group; TEVA resin uses the quaternary ammonium salt anion exchanger Aliquat® 336 immobilized on the surface of an inert support as a functional site; and TK200 resin is a novel extraction resin using trioctylphosphine oxide (TOPO) as the active extraction component. To evaluate the Pu enrichment performance advantage of the resin used in this invention, a comparative analysis of its adsorption performance with three currently mainstream commercial resins was conducted (only the resin was changed; all other treatment conditions were the same as in Example 1). The results are as follows: Figure 6 As shown. Under the same experimental conditions, the EtHex-POPhen / XAD-7 resin exhibits a Pu adsorption efficiency of over 99.9%, higher than the other three commonly used commercial resins, demonstrating extremely superior Pu adsorption capacity. Furthermore, in step S3, when the o-phenanthroline phosphonate macroporous resin composite material is activated with nitric acid, the EtHex-POPhen / XAD-7 resin can be activated at 0.1–8 M nitric acid concentrations; while conventional TK200 resin typically requires 8 M nitric acid, TEVA resin requires 1 M nitric acid, and TRU resin requires 3 M nitric acid, demonstrating that the present invention has a wider applicable acid concentration range.

[0065] To evaluate the reliability of the method, we analyzed spiked samples from different marine organisms. Recovery was determined using the same method as steps 1-4 of Example 1, with low, medium, and high levels of [specific substances] added to these marine organism samples. 239 Pu. The recovery rate was evaluated by calculating the ratio of the average detected concentration to the theoretical concentration of the spiked samples, and the results are shown in Table 3. Spiked samples at each spiking level were analyzed multiple times (n=3), and the repeatability of the method was evaluated by calculating the relative standard deviation.

[0066] Table 3 Spiked recoveries and relative standard deviations of different marine organisms

[0067]

[0068] As shown in Table 3, the spiked recoveries of all samples exhibited good performance, ranging from 68.2% to 87.9%, with relative standard deviations ranging from 3.6% to 6.2%. These results demonstrate that our quantitative method has good recovery and repeatability.

[0069] This invention provides a radioactive 239 The separation method and application of Pu: This separation method collects the product containing Pu after acid digestion of large-volume samples by centrifugation. 239The Pu digestion solution reduces unnecessary time consumption in traditional processing, thus significantly improving overall analytical efficiency. The synthesized novel EtHex-POPhen / XAD-7 resin is effective for trace amounts of [unspecified substance] in marine biological samples. 239 Pu exhibits excellent enrichment capabilities, with an enrichment efficiency exceeding 99.9%. One kg of marine biological sample can be successfully encapsulated on resin using a 30 mL mixture of 0.1 M H₂C₂O₄ and 0.1 M NH₂OH·HCl. 239 It effectively elutes uranium (Pu) and exhibits good uranium separation performance under high uranium conditions, with a uranium removal factor reaching 10. 5 .pass 239 Spiking experiments with Pu standard solutions verified the accuracy and reliability of the method. The recoveries of different spiking gradients were 68.2%–87.9%, and the relative standard deviations (RSDs) were 3.6–6.2%.

[0070] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A type of radioactivity 239 The method for separating Pu is characterized by, The separation method employs a macroporous resin composite material of o-phenanthroline phosphonate to separate marine biological samples. 239 Pu is used for enrichment and separation, including: S1. After collecting marine biological samples, ashing and acid digestion were performed. The supernatant was collected by centrifugation, and then enriched and purified to obtain the product containing... 239 Pu's sample solution; S2, prepare o-phenanthroline phosphonate ligand, dissolve the o-phenanthroline phosphonate ligand in an organic solvent, then add the pretreated solid support material, stir and mix, and dry to obtain the o-phenanthroline phosphonate macroporous resin composite material, the mass ratio of the o-phenanthroline phosphonate ligand to the solid support material is 1:2-4; S3, the o-phenanthroline phosphonate macroporous resin composite material is activated with nitric acid, containing... 239 A sample solution of Pu was injected into the activated o-phenanthroline phosphonate macroporous resin composite material. The o-phenanthroline phosphonate macroporous resin composite material was then repeatedly eluted with eluent to obtain a solution containing Pu. 239 The eluent of Pu, wherein the eluent comprises a first eluent and a second eluent, the first eluent comprising a nitric acid solution and a hydrochloric acid solution, and the second eluent being a mixed solution containing an oxalic acid compound and hydroxylamine hydrochloride.

2. The separation method according to claim 1, characterized in that, The o-phenanthroline phosphonate macroporous resin composite material is composed of a solid support material and o-phenanthroline phosphonate ligands loaded thereon. The structural formula of the o-phenanthroline phosphonate ligands is as follows: 。 3. The separation method according to claim 1, characterized in that, The concentration of the nitric acid solution in the first eluent is 4-6 M, and the concentration of the hydrochloric acid solution is 7-9 M.

4. The separation method according to claim 1, characterized in that, In the second eluent, the concentration ratio of the oxalic acid compound to the hydroxylamine hydrochloride is 1:0.8-1.

2.

5. The separation method according to claim 1, characterized in that, The oxalic acid compounds include oxalic acid.

6. The separation method according to claim 1, characterized in that, In S2, the preparation of the o-phenanthroline phosphonate ligand includes: 2,9-Dichloro-1,10-phenanthroline and bis(2-ethylhexyl) phosphite were added to a mixed solution and refluxed. The mixture was then filtered and rotary evaporated to obtain a crude product, which was purified by silica gel column chromatography to obtain o-phenanthroline phosphonate ligand. The mixed solution comprises palladium acetate, 1,1'-bis(diphenylphosphine)ferrocene, triethylamine, and anhydrous toluene.

7. The separation method according to claim 6, characterized in that, The molar ratio of the 2,9-dichloro-1,10-phenanthroline to the bis(2-ethylhexyl) phosphite is 1:2 to 1:

3.

8. The separation method according to claim 6, characterized in that, The molar ratio of palladium acetate to 1,1'-bis(diphenylphosphine)ferrocene is 1:

2.

9. The separation method according to claim 1, characterized in that, In S1, the centrifugation speed is 4200-4600 rpm and the centrifugation time is 8-12 min.

10. The separation method according to claim 2, wherein the solid support material is selected from porous resins, and the porous resins include XAD-7 resin and / or XAD-6 resin.

11. A separation method according to any one of claims 1-10 for ultra-trace samples of marine organisms. 239 Applications in Pu analysis.

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