Radionuclide production

Abstract

213 Bi daughter radionuclides 225 A radionuclide separation system for separating Ac from its parent radionuclide, comprising: 225 An inlet for filling the column (10) with a liquid solution containing the parent radionuclide Ac and a 225 Ac parent radionuclide and / or 213 To enable selective desorption of Bi daughter radionuclides, 225 Ac parent radionuclide and 213 said column (10) containing an adsorbent material capable of interacting with Bi daughter radionuclides; 225 Ac parent radionuclide and 213 Based on selective desorption of Bi daughter radionuclides 213 and an outlet for selectively obtaining a Bi daughter radionuclide, wherein the sorbent material is a carbon-based sorbent material.

Description

[Technical field]

[0001] The present invention relates to the field of radionuclides. More particularly, the present invention relates to 213 The present invention relates to a system and method for separating radionuclides, such as Bi radionuclides. [Background technology]

[0002] The use of high-purity radionuclides is becoming increasingly important for diagnostics and medicine. In particular, targeted alpha therapy is a promising technique for treating various cancers and other diseases by the emission of alpha particles. Compared to beta particles and Auger electrons, alpha particles are more effective ionizing agents with a lower penetration range (50-100 μm) and higher linear energy transfer (50-230 keV / μm), maximizing the destruction of malignant cells while minimizing damage to surrounding normal tissue.

[0003] Recently, 213 Bi has high specific activity, effective half-life (t 1 / 2 It has emerged as a particularly promising alpha emitter due to its α decay rate (ΔT = 45.6 min), high α decay rate, and the absence of long-lived intermediates. Clinically, it has been investigated for the treatment of various cancers, including leukemia, melanoma, brain tumors, and neuroendocrine tumors. 213 Bi has been used. In the prior art, a relatively long-lived parent nuclide 225 Ac(t 1 / 2 = 9.92 days) 225 Ac / 213 Bi generator and its short-lived daughter nuclides 213 It has been applied as a direct source for the production of Bi.

[0004] Radionuclide generators allow for efficient radiochemical separation of decaying parent and daughter radionuclides so that the daughter nuclides are obtained with high radionuclide and radiochemical purity. Typically in radionuclide generator systems, a relatively long-lived radionuclide is used as the parent radionuclide, which decays into daughter radionuclides with shorter half-lives. There are many advantages associated with radionuclide generators, including: 1) the ability to ensure clinical availability of short-lived daughter radionuclides without relying on the production capacity of a nuclear reactor or accelerator; 2) the ability to provide short-lived daughter radionuclides with high specific activity and in carrier-free form at low cost; and 3) the ability to provide short-lived daughter radionuclides for medical use in hospitals located far away from nuclide production facilities. For example, radionuclide generators may be located in hospitals, allowing for the production of relatively pure samples of daughter radionuclides at the location where they are needed.

[0005] Two particular types of radionuclide generators known in the art are direct radionuclide generators and inverted radionuclide generators.

[0006] In a typical direct radionuclide generator, a column is packed with a sorbent material, i.e., a sorbent onto which the parent isotope is adsorbed and from which the daughter isotopes can be eluted at regular time intervals with different eluents. The sorbent material preferably has a high affinity for the parent isotope, and the generator eluent must be free of the parent isotope. Furthermore, the sorbent material in a radionuclide generator must promote high and reliable (i.e., reproducible) yields and high purity of the daughter radionuclides to meet the increasing need for alpha emitters in clinical research.

[0007] In an inverted radionuclide generator system, the parent radionuclide is stored in a solution (typically a mixture containing the parent radionuclide and the daughter radionuclides formed by the decay of the parent radionuclide) to reduce the effect of radiolytic damage on the performance of the sorbent material. As described in MCALISTER, DR and HORWITZ, EP "Automated two column generator systems for medical radionuclides". Applied Radiation and Isotopes, 2009, 67(11), 1985-1991, in an inverted radionuclide generator system, the solution, i.e., the mixture containing the daughter and parent radionuclides, is typically passed through a chromatographic column (primary separation column, PSC) specific for the desired daughter radionuclide and eluted. The daughter radionuclides are retained on the PSC, while the parent radionuclide passes through unretained. A small amount of wash solution is then passed through the PSC to ensure near complete recovery of the parent nuclide in the eluent. The eluate containing the parent nuclide is then stored for further ingrowth of the desired daughter nuclide and further processing. The daughter nuclide is removed from the PSC and the removed solution is passed through a second column (guard column) specific for the parent nuclide. The guard column thereby provides further decontamination of the parent radionuclide from the daughter product, further improving the separation of the daughter radionuclide from the parent radionuclide, thus obtaining a daughter product of higher purity.

[0008] Several sorbent materials (also known in the art as "resins") are known in the art that can be used in the direct and / or inversion radionuclide generator systems described above. However, these sorbent materials typically suffer from several drawbacks. For example, the separation properties of organic resins (such as commercially available AG MP-50 and UTEVA) are subject to radiolytic damage, resulting in short on-column lifetimes (100 mCi). 225 It was concluded that the life of an AG MP-50 column packed with Ac was less than one day.) (VASILIEV, AN et al., "Medical 225 Ac / 213 Radiation stability of sorbents in medical Bismuth generators 225 Ac / 213 Bi generators).Solvent Extraction and Ion Exchange, 2021, 39(4), 353-372). To overcome (local) radiolytic damage to the sorbent, several approaches have been proposed. US Patent Application Publication No. 2005 / 0008558 A1 describes a method for distributing the radionuclides more homogeneously in the packed resin volume by adding complexing agents that avoid the concentration of the radionuclides in certain parts of the column. However, this approach is based on the use of high concentrations of acid, which can also affect the properties of the resin.

[0009] Another example of an adsorbent is a silica-based material that contains impregnated or grafted functional groups. However, silica can leach at low pH (typically pH<2) and therefore become unstable (YANTASEE, W., et al., "Selective capture of radionuclides (U, Pu, Th, Am and Co) using functional nanoporous sorbents", Journal of hazardous materials, 2019, 366, 677-683; ABBASI, WA and STREAT, M. "Sorption of uranium from nitric acid solution using TBP-impregnated activated carbons", Solvent extraction and ion exchange, 1998, 16(5), 1303-1320). Furthermore, it was found that silica-based resin structures are less affected by radiation than resins containing functional groups (VASILIEV, AN, et al., "Medical 225 Ac / 213Radiation stability of sorbents in medical Bismuth generators 225 Ac / 213 "Bi generators", Solvent Extraction and Ion Exchange, 2021, 39(4), 353-372. Finally, Isolute SCX-2 and Isolute SCX 213 The Bi yield is relatively low (67-72%) (MOORE, MA et al., " 225 from its parent solution of Ac 213 The Performance of Two Silica-Based Ion Exchange Resins in the Separation of Bi 213 Bi from its parent solution of 225 Ac), Applied Radiation and Isotopes, 2018, 141, 68-72).

[0010] As a further example, the adsorbent material may include zirconia-based materials. Disadvantages include leaching of components of the material, such as T-39 (96% ZrO2 and 4% Y2O3), in strong acid solutions (VASILIEV, AN et al., "Inorganic Adsorbents Based on 225 Ac / 213 Bi generator ( 225 Ac / 213 Bi generator based on inorganic sorbents),Radiochimica Acta,2019,107(12),1203-1211). Furthermore, due to the accumulation of the adsorbent dissolution products in the solution, 213 The Bi yield may decrease after 25 elutions. 213 The Bi elution yield was reduced to 50%. Such a reduction is unacceptable for generator applications. Furthermore, the washing solution reduced the Bi elution yield by 0.5-1% per elution. 225 It was found that Ac was lost.

[0011] As a final example, PNNL (Pacific Northwest National Laboratory) has disclosed a Bi generator that uses an organic anion exchange resin (VASILIEV, AN et al., "Medical Bismuth Generators"). 225 Ac / 213 Radiation stability of sorbents in medical Bismuth generators 225 Ac / 213 Bi generators”, Solvent Extraction and Ion Exchange, 2021, 39(4), 353-372; U.S. Patent No. 005749042A). 213 Bi sample, i.e. 213 The Bi eluent had an activity of about 0.1% of its initial activity. 225 It seems to contain Ac impurities. 225 2-3% of Ac is lost. Finally, the adsorbent is subject to radiolytic damage.

[0012] Thus, there remains a need in the art for an apparatus and method that addresses at least some of the above problems. Summary of the Invention

[0013] It is an object of the present invention to provide a material, device or method suitable for separating radionuclides.

[0014] The above objectives are achieved by a method and apparatus according to the present invention.

[0015] An advantage of embodiments of the present invention is that the sorbent material may be mechanically, chemically and radiolytically stable. An advantage of embodiments of the present invention is that the sorbent material may not have leaching issues. An advantage of embodiments of the present invention is that the sorbent material may have a long life. An advantage of embodiments of the present invention is that the sorbent material may be used to produce high activity 225 Ac / 213 An advantage of embodiments of the present invention is that the adsorbent material can be used to separate Bi. 213The advantage is that a high Bi yield can be obtained.

[0016] In a first aspect, the present invention relates to a radionuclide separation system for separating daughter radionuclides from parent radionuclides. The radionuclide separation system comprises an inlet for loading a column with a liquid solution comprising the parent radionuclides. The radionuclide separation system further comprises a column comprising a sorbent material capable of interacting with the parent and daughter radionuclides to allow selective desorption of the parent and / or daughter radionuclides at different moments in time. Here, the sorbent material is a carbon-based sorbent material. The radionuclide separation system further comprises an outlet for selectively obtaining said daughter radionuclides based on said selective desorption of the parent and daughter radionuclides. An advantage of embodiments of the present invention is that the carbon-based sorbent material may be formed from an inert carbon material, which may provide the sorbent material with good stability. For example, carbon structures may have a high resistance to strong acid solutions (pH<2) compared to inorganic metal oxides. Furthermore, carbon structures with polycyclic aromatic rings may have a higher radiation stability compared to organic resins.

[0017] In some embodiments, the carbon structure may have good radiation stability compared to other organic adsorbents, i.e., the carbon structure may have a higher half-maximum dose than most organic adsorbents. Half-maximum dose may be defined as the radiation dose at which a loss of 50% of the exchange capacity of a given adsorbent occurs. A complete definition of half-maximum dose is given in the technical report "Radiation effects on ion exchange materials" by Gangwer TE et al. (Brookhaven National Laboratory) in BNL-50781, published November 1, 1977. In some embodiments, the carbon structure may have a half-maximum dose of at least 10 MGy.

[0018] The inert carbon material may be, for example, inert with respect to radionuclides and solvents. An advantage of embodiments of the present invention is that they provide a technique for separating radionuclides in which the columns used in the separation process are not subject to radiolytic damage or are subject to less radiolytic damage compared to existing columns. An advantage of embodiments of the present invention is that they provide a technique for separating radionuclides in which the columns used in the separation process are not subject to radiolytic damage or are subject to less radiolytic damage compared to existing columns. 225 Ac / 213 Bi (e.g., at least 100 mCi 225 Ac) to meet the requirements in medical applications due to their high radiation stability or improved separation methods.

[0019] In embodiments referring to carbon-based materials, where reference may be made to, for example, inorganic carbon-based materials, e.g. unmodified (initial) carbon structures, e.g. having a H / C ratio (molar ratio) of less than 1, e.g. less than 0.9, are produced by pyrolysis of polymers or polysaccharides at high temperatures, e.g. above 300°C, e.g. above 400°C.

[0020] The column may be any column suitable for containing a sorbent material. Typically, the sorbent material is included in the fluid path between the inlet and the outlet. In some embodiments, the column may be a chromatography column, as is well known in the art. The volume of the sorbent material may be any suitable volume and may be selected as appropriate for the intended application. In some embodiments, the volume of the carbon-based sorbent material may be, for example, 0.1-10 mL. Preferably, the amount of sorbent material packed in the column is as small as possible. Typically, the smaller the bed volume of the column, the higher the concentration of isotopes, i.e., daughter radionuclides, that can be obtained.

[0021] In some embodiments, the carbon-based sorbent material comprises, or for example consists essentially of, an active material (e.g., activated carbon) together with one or more compounds that contain one or more functional groups. In some embodiments, one or more functional groups may be grafted or impregnated. The functional groups are preferably grafted, which allows for good stability of the functional groups in the carbon-based sorbent material. The advantage of these embodiments is that the adsorption affinity may be specifically optimized for the parent radionuclide and / or the daughter radionuclide. At the same time, these embodiments may also provide high radiolytic stability.

[0022] In some embodiments, the one or more functional groups are selected from one or more oxygen-containing groups, such as carboxyl, hydroxyl, carbonyl, or epoxide, and / or one or more sulfur-containing groups, such as sulfonic acid, sulfoxide, or sulfone, and / or one or more phosphorus-containing groups, such as phosphoric acid, phosphinic acid, phosphonic acid, or phosphine oxide. In some embodiments, the functional groups may be selected from -COOH, -C-OH, -C=O, -PO4H, and -SO3H. An advantage of these embodiments is that one or more functional groups can be used to tune the interaction of the sorbent material with the radionuclides and thus tune the present radionuclide separation system. That is, one or more functional groups may be used to optimize the sorbent material for use in a direct radionuclide separation system or a reversal radionuclide separation system. The introduction of different functional groups (e.g., -COOH, -C-OH, -C=O, -PO4H, and -SO3H) can be used to optimize the sorbent material for use in a direct radionuclide separation system or a reversal radionuclide separation system, for example. 213 Bi and / or 225 The interaction mechanism with Ac metal ions may be tailored to obtain sorbent materials with suitable properties for direct and / or reversal radionuclide separation systems.

[0023] For example, functional groups may be used to tailor the electrostatic interaction and / or ion exchange between the carbon-based sorbent material and the nuclide. The electrostatic interaction and / or ion exchange may be highly sensitive to the pH, ionic strength and / or salt concentration of the solution, and thus potentially tunable. The electrostatic interaction and / or ion exchange mechanism may be 225 may be the dominant adsorption mechanism for Ac, 213 Bi can also interact with such functional groups (e.g., -COOH, -C-OH, -C=O, -PO4H and -SO3H). With regard to these mechanisms, the following functional groups have been found to have some particularly good properties: sulfonic acid groups, carboxylic acid groups and bis(2-ethylhexyl)phosphate.

[0024] In another example, the functional groups may be used to achieve inner sphere complexation of radionuclides (e.g., parent and / or daughter nuclides) with phosphate groups (-POH), carbonyls (-C=O), hydroxyl groups (-C-OH), and carboxylic acids (-COOH). 213 Since Bi interacts with these functional groups (i.e., forms complexes), 213 Bi is 225 It may have a stronger affinity in this regard compared to Ac.

[0025] In some embodiments, the carbon-based sorbent material comprises one or more of pyrolyzed polymers or polysaccharides, such as cellulose, cellulose derivatives, starches or phenolic resins, activated carbon, graphitic carbon nitride, graphitic carbon (i.e., essentially composed of carbon) and carbon molecular sieves. In some embodiments, the carbon-based sorbent material consists essentially of one of these materials and optionally the functional groups. In some embodiments, the carbon-based sorbent material is activated carbon or carbon molecular sieves. In particular, polycyclic aromatic structures have higher radiation stability than other materials used as supports, such as silica and organic resins. In some embodiments, the sorbent material is preferably a polycyclic aromatic carbon structure with grafted functional groups. An advantage of these embodiments is that the sorbent material may have high radiolytic stability, which may be particularly advantageous for use in the present radionuclide separation system.

[0026] Examples of functionalized derivatives of carbon-based adsorbent materials are sulfonated carbon materials, oxidized carbon materials, and carbon materials containing impregnated extractants or cation exchange materials, such as bis(2-ethylhexyl) phosphate impregnated activated carbon, where the carbon material is applied as an inert support.

[0027] The shape of the adsorbent material may also affect the structural properties of the adsorbent material, which may be a powder, and possibly the presence of functional groups on the surface. In some embodiments, the adsorbent material is formed into beads, or the carbon-based adsorbent material is provided as a shell of beads, e.g., spherical particles. Preferably, the adsorbent material is formed into spherical beads, e.g., to ensure a uniform flow pattern in the column and a lower pressure drop in the column. In some embodiments, the carbon-based adsorbent material is formed into beads having a size of 5 μm to 1 mm, e.g., 10 μm to 500 μm, e.g., 10 μm to 250 μm, e.g., 10 μm to 150 μm, e.g., 50 μm to 150 μm. The advantage of these embodiments is that the column can be rapidly filled and rapid purification can be achieved. It is also noted that other shapes than beads can be used, such as, but not limited to, extruded honeycombs, 3D printed monoliths, tubular structures, and non-spherical granules.

[0028] In some embodiments, the adsorbent material may have a porosity between 0% and 70%. In some embodiments, the pore size may be between 0 and 100 nm. In some embodiments, the surface area of ​​the adsorbent material may be between 100 m 2 / g, e.g. 50m 2 / g, e.g. 25m 2 / g, e.g. 10m 2 / g. An advantage of these embodiments is that rapid purification can be achieved with limited surface area. A small surface area is desirable to avoid trapping of the isotope inside the adsorbent structure, which increases elution efficiency by reducing elution paths.

[0029] Carbon materials may be selected for further functionalization to form carbon-based sorbent materials. Functionalization, particularly by grafting, may be easier for some carbon materials than others. Preferably, the carbon material may have many defects in its carbon structure or may already have specific functional groups on its surface that can be converted to functional groups according to embodiments of the present invention (e.g., activated carbon). Furthermore, functionalization by grafting imposes different requirements on the carbon material than impregnation. Depending on the type of generator (i.e., inverted radionuclide separation system or direct radionuclide separation system), the materials and processes used for radionuclide generation may then be selected. Adsorption performance may be adjusted, particularly by ionic strength and / or pH.

[0030] The present invention is primarily concerned with parent radionuclides 225 As Ac and daughter radionuclides 213 Although described with respect to Bi, the invention should in no way be construed as being limited to these embodiments. In some embodiments, the radionuclide separation system comprises: 225 From Ac 213 Bi, 113 From Sn 113m In, 87 From Y 87m Sr, 232 From U 228 Th and / or 224 Ra and / or 220 Rn and / or 216 Po and / or 212 Pb, and 227 From Ac 211 Pb, or possibly 191 From Os 191m The radionuclide separation system is based on the decay of a parent compound to a daughter compound, as will be appreciated by those skilled in the art. 213 For separating Bi radionuclides 225 From Ac 213The decay of 1,2-dichloro-1,3-diphenyl-2,4-tetraphenyltetrazolium is based on the decay of 1,2-dichloro-1,3-diphenyl-2,4-tetrazolium ... 213 The elution of Bi radionuclides was performed using a column comprising a sorbent material according to the state of the art, e.g. a silica-based material. 213 An advantage of embodiments of the present invention is that the elution of Bi radionuclides can be high compared to that of the carbon-based sorbent material. 225 Ac / 213 Bi, e.g. at least 100 mCi 225 The advantage is that Ac can be separated.

[0031] The affinity of the sorbent material for the parent and daughter radionuclides may depend on the pH and / or ionic strength of the solvent, e.g., mixture or eluent, in contact with the sorbent. In some embodiments, the ability of the sorbent material to interact with the parent and daughter radionuclides to enable selective desorption of the parent and / or daughter radionuclides at different moments in time includes that the sorbent material has at least different affinities within a particular pH range and a particular ionic strength and / or salt concentration range, as is the case for carbon-based sorbent materials according to embodiments of the present invention.

[0032] In some embodiments, the radionuclide separation system is a direct radionuclide separation system, and the carbon-based sorbent material has a strong affinity for both the parent and daughter radionuclides to selectively desorb the daughter radionuclides. In some embodiments, the mixture preferably contains the parent and daughter radionuclides at a low salt concentration, e.g., a salt concentration of less than 1.0 M, e.g., a salt concentration of less than 0.5 M. Preferably, the pH of the mixture is at least greater than the pK a For example, the pH is greater than 1.47 for bis(2-ethylhexyl) phosphate impregnated activated carbon, for example, the pH is greater than 2 for bis(2-ethylhexyl) phosphate impregnated activated carbon, so that the parent nuclide is adsorbed by electrostatic attraction and / or ion exchange.

[0033] Here, the daughter radionuclides may be selectively desorbed using a first eluent, by interacting more preferably with the eluting ions than with the sorbent material, and the parent radionuclides may then be eluted by an acid solution for reuse and to reduce radiolytic damage to the sorbent.

[0034] The eluent for the daughter radionuclide may comprise NaI, NaCl, HI, HCl or a combination thereof, preferably at least 0.1 M, at least 0.2 M, preferably at least 0.4 M, etc. In some embodiments, the pH value of the eluent is at least the pK a For example, the eluent may contain at least 0.45 M NaI at a pH of at least 2 for bis(2-ethylhexyl) phosphate impregnated activated carbon.

[0035] The parent radionuclide may be desorbed from the generator column using an acidic solution (e.g., HNO3 or HCl solution). The concentration of HNO3 in said solution may be at least 0.1M, preferably at least 0.2M, such as 0.1-0.5M, preferably 0.2M-0.3M. Advantages of embodiments of the present invention include: 225 The contact time of Ac with the carbon-based adsorbent material was reduced and the 225 An advantage of embodiments of the present invention is that it is possible to achieve a uniform distribution of Ac, thereby extending the life of the column. 225 The advantage is that Ac can be eluted from the column with a relatively weak acid solution.

[0036] In other embodiments, the radionuclide separation system may be an inverted radionuclide separation system, where the carbon-based sorbent material is configured to have a higher affinity for the daughter radionuclides than the parent radionuclides. In some embodiments, the carbon-based sorbent material includes one or more of phosphate, phosphonate, phosphinate, carbonyl, hydroxyl, or carboxylate groups. These functional groups may result in a sorbent material that has a higher affinity for the daughter radionuclides than the parent radionuclides. In embodiments where the radionuclide separation system is an inverted radionuclide separation system, the radionuclide separation system may include a sorbent material (e.g., AG MP-50 or Ac resin) that has a higher affinity for the parent radionuclides than the daughter radionuclides, and a second column having an inlet and an outlet. In some embodiments, the outlet of the column may be configured to be fluidly connected to the inlet of the second column as a removal solution containing the daughter radionuclides released from the column flows out of the column. The sorbent material of the second column may not need to be a carbon-based sorbent material since the daughter solution (which may cause most of the radiolytic damage) has a relatively short retention time in the second column, although the sorbent material of the second column may also include a carbon-based sorbent material, and this feature may be described separately in conjunction with the carbon-based sorbent material of that column. An advantage of the embodiment with a second column is that a daughter radionuclide eluate of higher purity (i.e., substantially free of parent radionuclides) may be obtained.

[0037] Any feature of any embodiment of the first aspect may be described independently with respect to any corresponding embodiment of the second aspect of the invention.

[0038] In a second aspect, the present invention relates to a method for separating radionuclides comprising the steps of: loading a mixture of parent and daughter radionuclides into a column comprising a carbon-based sorbent material; allowing the sorbent material, having an affinity for interacting with the parent and daughter radionuclides, to selectively interact with the parent and daughter radionuclides to allow selective desorption of the parent and daughter radionuclides; and selectively desorbing the parent and daughter radionuclides after said interaction to selectively obtain the daughter radionuclides. In some embodiments, the method may be performed using a radionuclide separation system as described with respect to the first aspect of the invention.

[0039] In some embodiments, the mixture may include the parent and daughter radionuclides dissolved in water. The advantage of water is that its pH can be easily adjusted and it can also dissolve ions efficiently and in high concentrations.

[0040] In some embodiments, the temporally distinct moments may include temporally subsequent selective desorption of parent and / or daughter radionuclides.

[0041] These embodiments may relate to a direct radionuclide generator using, for example, a direct radionuclide separation system, where the sorbent material is configured to have a strong affinity for both the parent and daughter radionuclides for selectively desorbing the daughter radionuclide, and where the step of selectively obtaining the daughter radionuclide comprises at least a pK of the functional groups on the sorbent after the parent radionuclide is bound to the sorbent material. a and finally eluting the daughter radionuclide from the column with an eluent having a pH greater than that of the parent radionuclide (e.g. 225Ac) can be eluted by a solution containing HNO3, such as a solution containing HNO3 at a concentration of 0.1-0.5 M. The solution containing the parent radionuclide may then be stored and / or used as a mixture in subsequent cycles. This step may reduce radiolytic damage to the sorbent by reducing the contact time of the isotope with the sorbent, and may allow the parent radionuclide (e.g. 225 Ac) can be easily recycled and reused.

[0042] These embodiments may relate to inverted radionuclide production using, for example, an inverted radionuclide separation system. In some embodiments, the sorbent material is preferably configured to have a higher affinity for the daughter radionuclide than the parent radionuclide for binding thereto, and wherein selectively obtaining the daughter radionuclide includes washing the column and then removing the daughter radionuclide from the column into a removal solution.

[0043] In some embodiments, the mixture may include NaNO3 and HNO3, preferably at a total concentration higher than the ion concentration of the removal solution, such as at least 2 M, preferably at least 3 M. The mixture may have a pH of less than 2, preferably less than 1.

[0044] Washing may be performed, for example, using an eluent containing NaNO3 and HNO3, preferably with a total concentration of NaNO3 of at least 2M, preferably at least 3M. The eluent for washing may have a pH of less than 2, preferably less than 1. The pH of the washing solution may be lower than the pH of the mixture solution in the previous step. Preferably, the pH of the washing solution may be the same as the pH of the mixture solution in the previous step. This allows the parent radionuclide (e.g. 225 Ac) but not the daughter radionuclide (e.g. 213 Good adsorption of Bi may be obtained.

[0045] In some embodiments, the removal solution may comprise NaI, NaCl, HI, HCl, or HNO3, or a combination thereof, for example at a concentration of 0.1-3.0 M. Preferably, the removal solution has a pH of up to 2. In some embodiments, the removal solution may comprise 0.1-3.0 M NaI at a pH of up to 2, or 0.1-3.0 M NaCl at a pH of up to 2, or 0.1-3.0 M HCl, where HNO3 may be used to adjust the pH value of the solution.

[0046] In some embodiments, the removal solution is sometimes further added to a second column having a sorbent material with a higher affinity for the parent radionuclide, i.e., higher affinity for the daughter radionuclide, and the daughter product or daughter radionuclide is eluted from the second column after the sorbent material of the second column is allowed to interact with the remaining parent radionuclide in the removal solution.

[0047] Any feature of any embodiment of the second aspect may be described independently with respect to any embodiment of the first aspect of the invention.

[0048] Particular and preferred aspects of the invention are set out in the accompanying independent and dependent claims. Features from the dependent claims may be combined with features of the independent claims and with features of other dependent claims as appropriate and not merely as explicitly set out in the claims.

[0049] While there are constant improvements, modifications and advances being made to devices in this field, it is believed that the present concepts represent substantially new and novel improvements which involve departures from conventional practice and which will result in more efficient, stable and reliable devices of this type.

[0050] The above and other characteristics, features and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the invention. This description is given by way of example only and is not intended to limit the scope of the invention. The reference figures quoted below refer to the attached drawings. [Brief description of the drawings]

[0051] [Figure 1] FIG. 1A is a diagram of Kd at various pH values ​​for La3+ and Bi3+ between solvents and sulfonated Norit CA1 (sulfonated at a temperature of 80° C.) according to an embodiment of the present invention. FIG. 1B is a diagram of Kd at various pH values ​​for La3+ and Bi3+ between solvents and sulfonated Norit CA1 (sulfonated at a temperature of 150° C.) according to an embodiment of the present invention. FIG. 1C and FIG. 1D are plots of Kd as a function of ionic strength of a mixture of parent and daughter radionuclides applied to sulfonated Norit CA1 (sulfonated at a temperature of 150° C.) at pHs of 2 and 1, respectively, according to an embodiment of the present invention. FIG. 1E is a diagram of the desorption rate D (%) of La3+ and Bi3+ from sulfonated Norit CA1 (sulfonated at a sulfonation temperature of 150° C.). 1F and 1G are graphs of the Kd for La3+ and Bi3+ at pH 2 and 1, respectively, between solvent and sulfonated Norit CA1 (sulfonated at a temperature of 150° C.) after dose from 60Co. [Diagram 2] 2A and 2B are plots of the Kd at various pH values ​​for Bi3+ and La3+ for graphitized carbon black (Carbopack X) and sulfonated graphitized carbon black, respectively. [Diagram 3] 3A and 3B are plots of the Kd for Bi3+ and La3+ at various pH values ​​for Carboxen 572 and sulfonated Carboxen 572, respectively. [Figure 4]FIG. 4A is a diagram of the Kd of La3+ and Bi3+ for sulfonated carbonized methylcellulose carbonized at various temperatures and a pH of 2. FIG. 4B is a diagram of the R(%) of La3+ or Bi3+ for sulfonated carbonized methylcellulose carbonized at various temperatures and a pH of 2. FIG. 4C is a diagram of the Kd of La3+ or Bi3+ for sulfonated carbonized methylcellulose carbonized at various temperatures and a pH of 1. FIG. 4D is a diagram of the R(%) of La3+ or Bi3+ for sulfonated carbonized methylcellulose carbonized at various temperatures and a pH of 1. [Diagram 5] 5A is a plot of R(%) at various pH values ​​for Bi3+ and La3+ for the adsorbent material Norit CA1 activated carbon according to an embodiment of the present invention, and FIG. 5B is a plot of the high resolution XPS oxygen 1s spectrum of Norit CA1. [Figure 6] 6A and 6B are diagrams of R (%) at various pH values ​​for Bi3+ and La3+ and D (%) for different concentrations of NaI at pH 2 for the adsorbent material HDEHP-AC, respectively, in accordance with an embodiment of the present invention. [Figure 7] 7A and 7B are schematic diagrams of the conceptual design and process flow for an inverted 225Ac / 213Bi separation system with a guard column, according to an embodiment of the present invention. [Figure 8] Figure 8A is a plot of Kd of Bi3+ and La3+ for HDEHP-AC for various S / L ratios, where S is the amount of adsorbent material in milligrams and L is the amount of the mixture in milliliters. Figure 8B is a plot of D(%) of Bi3+ and La3+ for HDEHP-AC for various concentrations of HNO3. Figure 8C is a plot of R(%) of Bi3+ and La3+ for HDEHP-AC for various concentrations of NaNO3. [Figure 9] FIG. 1 is a schematic diagram of the conceptual design and process flow for a direct 225Ac / 213Bi separation system according to an embodiment of the present invention. [Figure 10] Figure 10A is a diagram of SEM images of cellulose beads, carbonized cellulose beads, and sulfonated carbonized cellulose beads, and Figure 10B is a diagram of Kd of Bi3+ and La3+ at various pH values ​​for sulfonated carbonized cellulose beads. [Figure 11] 1 illustrates two systems for separating radionuclides according to embodiments of the present invention.

[0052] In the different drawings, the same reference signs refer to the same or similar elements. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0053] The present invention will be described with respect to particular embodiments and with reference to certain drawings but the invention is not limited thereto but only by the claims. The drawings described are only schematic and are non-limiting. In the drawings, the size of some of the elements may be exaggerated for illustrative purposes and are not drawn to scale. The dimensions and relative dimensions do not correspond to actual implementations of the invention.

[0054] Moreover, terms such as "first," "second," and "third" in the specification and claims are used to distinguish between similar elements and are not necessarily intended to describe an order in time, space, or ranking or in any other manner. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein can be practiced in orders other than those described or illustrated herein.

[0055] Furthermore, terms such as "top," "bottom," "above," and "below" in this specification and claims are used for convenience and not necessarily to describe relative locations. It is to be understood that the terms so used are interchangeable under appropriate circumstances, and that the embodiments of the invention described herein can be practiced in orientations other than those described or illustrated herein.

[0056] It should be noted that the term "comprising" used in the claims should not be interpreted as being limited to the means listed thereafter, nor should it exclude other elements or steps. It should therefore be interpreted as specifying the presence of the recited features, integers, steps or components as they are referred to, but without excluding the presence or addition of one or more other features, integers, steps or components or groups thereof. The term "comprising" therefore encompasses situations where only the recited features are present, as well as situations where these features and one or more other features are present. The term "comprising" according to the present invention therefore also includes an embodiment where no further components are present. The scope of the expression "apparatus comprising means A and B" should therefore not be interpreted as being limited to an apparatus consisting of only components A and B. It means that in the context of the present invention, the only relevant components of the apparatus are A and B.

[0057] Similarly, the term "coupled" should not be interpreted as being limited to only direct connections. The terms "coupled" and "connected," along with their derivatives, may be used. It should be understood that these terms are not intended as synonyms for each other. Thus, the scope of the phrase "device A coupled to device B" should not be limited to devices or systems in which the output of device A is directly connected to the input of device B. It means that there is a path between the output of A and the input of B, which may be a path involving other devices or means. "Coupled" may mean that two or more elements are either in direct physical or electrical contact, or that two or more elements are not in direct contact with each other but still cooperate or interact with each other.

[0058] References throughout this specification to "one embodiment" mean that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of the present invention. Thus, the appearances of the phrase "in one embodiment" in various places throughout this specification do not necessarily all refer to the same embodiment, but may. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner, as would be apparent to one of ordinary skill in the art from this disclosure, in one or more embodiments.

[0059] Similarly, in describing exemplary embodiments of the present invention, it should be understood that various features of the invention may be grouped together in a single embodiment, figure, or description thereof to simplify the disclosure and aid in understanding one or more of the various inventive aspects. However, this method of disclosure should not be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Instead, as the following claims reflect, inventive aspects lie in less than all features of a single above-disclosed embodiment. Thus, the claims following this detailed description are expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of the present invention.

[0060] Furthermore, some embodiments described herein include some features that are included in other embodiments but not others, and combinations of features of different embodiments are intended to be within the scope of the present invention and form different embodiments as would be understood by one of ordinary skill in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.

[0061] Furthermore, some of the embodiments are described herein as methods or combinations of elements of methods that can be performed by a processor of a computer system or other means for performing that function. Thus, a processor with the necessary instructions for performing such a method or element of a method forms a means for performing the method or element of a method. Furthermore, the elements described herein of the apparatus embodiments are examples of means for performing the functions performed by the elements to practice the invention.

[0062] In the description provided herein, numerous specific details are set forth. However, it will be understood that embodiments of the present invention may be practiced without these specific details. In other instances, well-known methods, structures and techniques have not been shown in detail in order not to obscure an understanding of this description.

[0063] The following terms are provided solely to aid in the understanding of the invention.

[0064] "Functional group grafting" as used in the context of the present invention means that a chemical species is covalently attached to the surface of a solid, such as the surface of an adsorbent material. "Functional group impregnation" as used in the context of the present invention means that a chemical species is physically dispersed on the inner surface of a porous material.

[0065] As used in the context of the present invention, "CMS" is an abbreviation for carbon molecular sieve and CNT is an abbreviation for carbon nanotube.

[0066] In a first aspect, the present invention relates to a radionuclide separation system for separating daughter radionuclides from parent radionuclides. The radionuclide separation system comprises an inlet for loading a liquid solution comprising a parent radionuclide into a column. The radionuclide separation system further comprises a column comprising a sorbent material capable of interacting with a parent radionuclide and a daughter radionuclide to allow selective desorption of the parent radionuclide and / or the daughter radionuclide at different moments in time, wherein the sorbent material is a carbon-based sorbent material. The radionuclide separation system further comprises an outlet for selectively obtaining the daughter radionuclide based on said selective desorption of the parent radionuclide and the daughter radionuclide.

[0067] In a second aspect, the present invention relates to a method for separating radionuclides comprising the steps of: loading a mixture of parent and daughter radionuclides into a column comprising a carbon-based sorbent material; allowing the sorbent material, having an affinity for interacting with the parent and daughter radionuclides, to selectively interact with the parent and daughter radionuclides to allow selective desorption of the parent and / or daughter radionuclides; and selectively desorbing the parent and daughter radionuclides after said interaction to selectively obtain the daughter radionuclides.

[0068] By way of example, and not limitation, a schematic diagram of a direct and inversion radionuclide separation system is shown in FIG.

[0069] Several carbon-based sorbent materials for use in both the inverted radionuclide separation system and the direct radionuclide separation system according to embodiments of the present invention were prepared and tested as described below. 3+ (as a surrogate for the parent radionuclide) and Bi 3+ (as the daughter radionuclide) is used in the exemplary mixtures with water as the solvent, it should be understood that other parent and / or daughter radionuclides may also be used. 3+ without significantly altering the results obtained, as described below. 3+It can be considered to be replaceable by

[0070] In the following examples, we refer to the removal rate, R (%). We also refer to the desorption rate, D (%). Finally, we refer to the distribution coefficient, K, which is defined as the ratio of chemical concentrations between two media at equilibrium (e.g., between a carbon-based sorbent material and a mixture of parent and daughter radionuclides). d (mg / L) refers to the removal rate R (%) and distribution coefficient K d (mL / g) and desorption rate D (%) are as follows:

number

[0071] Below, examples of carbon-based sorbent materials for use in an inversion radionuclide separation system are provided. In the inversion radionuclide separation system, the parent radionuclide (in place of the parent radionuclide in the following examples, i.e., La) is deposited on the carbon-based sorbent material. 3+ ) 3+ ) occurs first followed by desorption of the daughter radionuclides from the carbon-based adsorbent material. EXAMPLES

[0072] Example 1 In this example, the adsorbent material is an activated carbon Norit CA1 with further grafting by H2SO4 or HNO3 treatment. Here, grafting results in an increase in oxygen content (in the case of both H2SO4 and HNO3 treatments), i.e., the formation of carboxyl (and other) groups, and an increase in sulfur content (in the case of H2SO4 treatment), i.e., the formation of sulfonic acid groups. For example, sulfonated Norit CA1 (150 °C) was made using concentrated H2SO4. Briefly, 15 g of Norit CA1 were mixed with 150 mL of concentrated sulfuric acid (95.0-98.0%) in a 500 mL round-bottom flask and stirred at room temperature for 10 min. The suspension was then heated to 150 °C with continuous stirring and maintained at that temperature for 3 h. After cooling the suspension at room temperature, the resulting black product was filtered and washed intensively with deionized water until sulfate ions were no longer detectable by barium chloride (addition of 5 drops of 1.0 M BaCl2 to 1 mL of filtrate). Finally, the sample was dried in an oven at 70° C. The prepared product was named Sulfonated Norit CA1 (150° C.).

[0073] The functional groups of sulfonated Norit CA1 (150 °C) were investigated by XPS. Two major oxygen environments could be assigned to O=C (531.3 eV) and OC (533.1 eV), which represent a potential mixture of hydroxyl, carbonyl and carboxylic acid functionalities. Furthermore, this lower binding energy component becomes sharper and more intense, which can then be assigned to overlapping sulfuric / sulfonic and carbonyl environments. The sulfur 2p spectrum of sulfonated Norit CA1 (150 °C) showed a mixture of two overlapping sulfur environments, which was tentatively assigned to a mixture of lower oxidation state species such as sulfonic or sulfuric acid (S 2p3 / 2 at 168.5 eV) and sulfurous or sulfinic acid (167.5 eV).

[0074] The mixture, for example, between a solvent (water) and sulfonated Norit CA1 (sulfonated at a temperature of 80° C.) 3+ and Bi 3+ K at various pH values dReference is now made to FIG. 1A, which illustrates the effect of pH on the partition coefficient of sulfonated Norit CA1 (sulfonated at a temperature of 80° C.). Here, the mixture of parent and daughter radionuclides is 1.02 μmol / L La 3+ and 0.57 μmol / L Bi 3+ The amount of adsorbent material was 20 mg and the volume of the mixture was 10 mL. The contact time was 24 h at room temperature. 3+ and Bi 3+ Further reference is made to FIG. 1B, which shows the effect of pH on the partition coefficient of sulfonated Norit CA1 (sulfonated at a temperature of 150° C.) for 10 μmol / L La 3+ and 10 μmol / L Bi 3+ The amount of adsorbent material was 10 mg and the amount of the mixture was 10 mL. The contact time was 24 h at room temperature. For sulfonated Norit CA1 (sulfonated at a temperature of 150° C.), the K d La 3+ Or Bi 3+ Reference is further made to Figures 1C and 1D, which show the effect of ionic strength (e.g., NaNO3) on a mixture containing 10 μmol / L La 3+ and 10 μmol / L Bi 3+ The amount of adsorbent material was 10 mg, and the volume of the mixture was 10 mL. Here, the experiment in FIG. 1C was performed at a pH of 2, and the experiment in FIG. 1D was performed at a pH of 1. By increasing the ionic strength and decreasing the pH, La 3+ / Bi 3+ It can be observed that higher selectivity in the adsorption of La can be achieved. The explanation for this observation is that sulfonation leads to the formation of oxygen-containing groups, which are 3+ and Bi 3+ As the pH increases, both carboxyl and other groups become increasingly deprotonated, providing more adsorption sites (K d¸Bi and K. d,La(Increase in H3O + (present at higher concentrations and lower pH) increases competition. Further increasing the ionic strength increases the ratio of carboxyl / sulfonic acid groups to La. 3+ The interaction with may be further reduced.

[0075] Figure 1E shows the La from sulfonated Norit CA1 (150 °C). 3+ and Bi 3+ The desorption rate of Cl is shown. - With increasing concentration, La 3+ and Bi 3+ The desorption efficiency of was initially rapid, then increased slightly, and reached 100% with 3 mol / L HCl eluent. The desorption mechanism was mainly the proton (H + ) and La 3+ / Bi 3+ Ion exchange selectivity reversal with Bi 3+ and Cl - Here, the starting solution mixture contains 10 μmol / L La in 10 mL of solution. 3+ and 10 μmol / L Bi 3+ The amount of adsorbent was 20 mg. Different volumes (0.084–3.333 mL) of 12.0 mol / L HCl stock solution were then added into it to achieve an HCl concentration range of 0.1–3.0 mol / L.

[0076] The radiation stability of sulfonated Norit CA1 (150°C) was also investigated by exposing the adsorbent to radiation and examining the effect on the adsorption performance. Briefly, 200 mg of sulfonated Norit CA1 (150°C) was mixed with 2 mL of 1 M HCl solution in a 4 mL glass vial; 60 The samples were irradiated with 10 μmol / L LaCo. The doses ranged from 0.5 to 11 MGy. A reference sample in 2 mL of 1 M HCl without radiation treatment was also examined. Finally, the samples were washed and dried in a desiccator and then used to study the adsorption properties. Here, the mixture of solutions was 10 μmol / L LaCo. 3+ and 10 μmol / L Bi3+ The amount of adsorbent material was 10 mg and the volume of the mixture was 10 mL. Here, the experiment in FIG. 3H was performed at a pH of 2 and the experiment in FIG. 3I was performed at a pH of 1. It can be observed that no changes that significantly deteriorate the adsorption performance could be observed, indicating that there is no obvious change in the number of adsorption sites.

[0077] Example 2 In this example, the adsorbent material included graphitized carbon black (Carbopack X) and sulfonated graphitized carbon black, where the reaction conditions for sulfonation were 5 g of Carbopack X in 50 mL of 97% H2SO4, 80°C, and 180 minutes, thereby forming sulfonated graphitized carbon black (i.e., sulfonated Carbopack X).

[0078] Bi between the solvent and graphitized carbon black (Carbopack X) or sulfonated graphitized carbon black 3+ and La 3+ K at various pH values d Reference is now made to FIG. 2, which is a diagram of the La for Carbopack X. FIG. 3+ and Bi 3+ The effect of pH on the partition coefficient of Bi between the solvent and sulfonated Carbopack X is shown. 3+ and La 3+ K at various pH values d Reference is further made to FIG. 2B, which is a diagram of La for sulfonated Carbopack X. 3+ and Bi 3+ The effect of pH on the partition coefficient of La in both cases is shown. 3+ and 0.57 μmol / L Bi 3+ The amount of adsorbent material was 20 mg and the volume of the mixture was 10 mL. The contact time was 24 h at room temperature. 3+ The adsorption of Bi was almost nonexistent, and the adsorption of Bi was suppressed due to insufficient functional groups. 3+It has low ability against La 3+ Bi 3+ It can be observed that after sulfonation there is a selectivity for Bi 3+ The adsorption capacity for sulphur increased. A gradual increase in the content of sulphur and oxygen was observed after sulphonation. Similar explanations for these observations as those for Example 1 above may be considered.

[0079] Example 3 In this example, the adsorbent material is carbon molecular sieve [Carboxen 572]. Here, sulfonated Carboxen 572 was synthesized using 2.5 g of Carboxen 572 in 25 mL of 97% H2SO4 at 150°C for 240 min.

[0080] La regarding Carboxen 572 3+ and Bi 3+ The effect of pH on the partition coefficient of Bi between solvents and Carboxen 572. 3+ and La 3+ K at various pH values d Refer to FIG. 3A, which is a diagram of the Bi between the solvent and sulfonated Carboxen 572. 3+ and La 3+ K at various pH values d , which shows the La for sulfonated Carboxen 572. 3+ and Bi 3+ Further reference is made to FIG. 3B, which shows the effect of pH on the partition coefficient of La. In both cases, the La concentration at 1.0 μmol / L 3+ and Bi at a concentration of 1.0 μmol / L 3+ A mixture of parent and daughter radionuclides containing was used. The amount of adsorbent material was 25 mg and the amount of the mixture was 10 mL. The contact time was 24 h at room temperature.

[0081] Carboxen 572 is La 3+ It can be observed that there is no adsorption of Bi due to insufficient functional groups. 3+ and La3+ Although low ability to 3+ Bi 3+ After sulfonation, the sulfur and oxygen content on the surface of the sulfonated Carboxen 572 increased with increasing Bi 3+ The adsorption capacity of La was increased. The same explanation for these observations as in Example 2 above may be considered. As observed in the results of Example 1, the adsorption capacity of La on sulfonated Carboxen 572 using NaNO3 solution was increased. 3+ Adsorption could be avoided.

[0082] Example 4 In this example, the adsorbent material is sulfonated carbonized methylcellulose (SCMC), where carbonized methylcellulose is formed by carbonization of methylcellulose at various temperatures. Below and in the figures, SCMC-[T] is used, where [T] indicates the temperature at which methylcellulose was carbonized. Here, sulfonation was performed in 97% H2SO4 at 150°C for 600 minutes.

[0083] La on sulfonated carbonized methylcellulose carbonized at various temperatures and pH of 2 and 1, respectively. 3+ and Bi 3+ K d Reference is made to Figures 4A and 4C, which are diagrams of the La 3+ Or Bi 3+ The effect of carbonization temperature and pH on the adsorption coefficient of La for sulfonated carbonized methylcellulose carbonized at various temperatures and pHs of 2 and 1, respectively. 3+ and Bi 3+ Reference is further made to Figures 4B and 4D, which are plots of R (%) for sulfonated carbonized methylcellulose. 3+ Or Bi 3+ The effect of carbonization temperature on the removal rate of La was shown in these experiments. In these experiments, the mixture of parent and daughter radionuclides was 10 μmol / L La 3+ or 10 μmol / L Bi 3+The amount of adsorbent material was 10 mg and the mixture volume was 10 mL. The contact time was 24 hours at room temperature. Some of the materials contained Bi 3+ Or La 3+ It can be observed that the sulfonated carbon materials exhibited high adsorption capacity for . The performance of SCMC-400 and SCMC-450 was certainly as good as that of commercially available ones (e.g., sulfonated Norit CA1). The adsorption performance of sulfonated carbon materials with soft structure was better than that of those with hard structure.

[0084] Example 5 In this example, the adsorbent material was activated carbon Norit CA1 (e.g., without further functionalization by grafting). 3+ and La 3+ Reference is now made to FIG. 5A, which is a plot of R (%) at various pH values ​​for La. 3+ and Bi 3+ Figure 5 shows the effect of pH on the adsorption rate of Norit CA1 to 10 μmol / L La. In the experiments performed for the results shown in Figure 5A, the mixture of parent and daughter radionuclides was diluted with 10 μmol / L La 3+ and 10 μmol / L Bi 3+ The amount of adsorbent material was 10 mg, the volume of the mixture was 10 mL, and the contact time was 24 hours at room temperature.

[0085] At pH ≦ 1.0, La 3+ / Bi 3+ High selectivity in the adsorption of La 3+ No adsorption ability was observed for Bi 3+ It can be observed that this type of activated carbon can achieve high removal rates for La. The explanation for this observation is that this type of activated carbon has different types of functional groups on its surface, 3+ and Bi 3+The key feature of the Norit CA1 is that it allows for different interaction mechanisms with the oxygen. The XPS oxygen 1s spectrum of Norit CA1 is shown in Figure 5B. The two main oxygen environments could be assigned to O=C (531.3 eV) and OC (533.1 eV), which represent a potential mixture of hydroxyl, carbonyl and carboxylate functionalities.

[0086] Example 6 In this example, the adsorbent material included HDEHP-AC (i.e., activated carbon modified with bis(2-ethylhexyl) phosphate). Bis(2-ethylhexyl) phosphate has the following chemical structure: [ka] has.

[0087] Bismuth on the adsorbent material HDEHP-AC 3+ and La 3+ Reference is now made to FIG. 6A, which is a plot of R (%) at various pH values ​​for La. 3+ and Bi 3+ The effect of pH on the adsorption (i.e., removal) rate of HDEHP-AC on La 3+ The adsorption capacity for Bi is more sensitive to the short pH range of 2 to 1. 3+ It was found that La shows relatively low dependence over this pH range. 3+ The removal rate of La rapidly decreased from about 80% at pH 2 to about 0 at pH 1. At pH 2, a large amount of La 3+ The ions were adsorbed onto the HDEHP-AC by electrostatic attraction, which was attributed to the deprotonated PO4H groups from HDEHP (pK a : approx. 1.47). At pH 1, H + Ion interference and HDEHP-AC and La 3+ Due to the lack of electrostatic attraction with the La ions, 3+ There was almost no adsorption capacity for pH. <pK a H in acidic solution in the case + By ion exchange with La 3+It was also found that La was much more easily desorbed. 3+ Compared with Bi at pH 1 3+ The removal rate of Bi 3+ Complexation of Bi with P=O and P-OH groups on the surface of HDEHP-AC 3+ However, at pH 1 to pH 0.5, the hydrolysis of Bi 3+ The removal rate of Bi rapidly decreased from about 93% to 37%, which was 3+ Electrostatic repulsion between the protonated functional group and excess H + Based on the effect of pH, HDEHP-AC at low pH (e.g. pH 1) was found to be more efficient at adsorbing La 3+ / Bi 3+ From the mixture solution, Bi 3+ In summary, when the pH is up to 1.0, La 3+ / Bi 3+ High selectivity in the adsorption of La 3+ Almost no adsorption capacity was observed for Zn, but a high removal rate for Bi was achieved.

[0088] Further reference is made to FIG. 6B, which shows the D(%) of different concentrations of NaI for the adsorbent material HDEHP-AC. 3+ The desorption rate for was found to be relatively higher in high concentration NaI solution at pH 2. In conjunction with the effect of pH, the inventors used NaI solution to 213 It can be concluded that Bi can be eluted. Furthermore, as the pH of the eluent decreases, 213 Bi can be increased. Preferably, the pH of the eluent is at most 2.

[0089] As a result, FIG. 6B shows that La 3+ and Bi 3+ The effect of elution concentration on the desorption rate of La at a concentration of 10 μmol / L was shown for both examples. 3+ and Bi at a concentration of 10 μmol / L 3+A mixture of parent and daughter radionuclides containing the parent radionuclide and the daughter radionuclide was used. In Figure 6A, the amount of adsorbent material was 60 mg, the amount of the mixture was 30 mL, and the contact time (i.e., contact of the adsorbent material with the mixture) was 24 hours at room temperature, i.e., 25°C. In Figure 6B, the amount of adsorbent material was 400 mg, the amount of the mixture was about 30 mL, the pH of the mixture was 2, and the contact time was 24 hours at room temperature.

[0090] Example 7: General principle of the inversion generator 1 illustrates a more general principle according to an embodiment of the present invention; 225 Ac / 213 Please refer to FIG. 7A, which is a schematic of the conceptual design and process flow for a Bi separation system. This example specifically relates to 213 Bi 225 Although it is intended for separation from Ac, separation of other daughter radionuclides from other parent radionuclides may be performed with the same or similar systems according to embodiments of the present invention. The arrows indicating the direction of flow of fluids (e.g. mixture / eluent / removal solution / ...) along with the respective numbers refer to the following method steps according to embodiments of the present invention:

[0091] Step 0 (preparation step, not shown): 225 Ac and 213 The optimal ionic strength and pH range may be selected based on the density of active sites of Bi. Column 10 is typically conditioned with HNO3 (e.g., 0.1 M), which may be introduced through the inlet of the column.

[0092] Step 1: Next, 225 Ac (parent radionuclide) and 213 A mixture of parent and daughter radionuclides including Bi (the daughter radionuclide) is passed through column 10, which may include, for example, introducing the mixture into column 10 via an inlet. The mixture may further include, for example, NaNO3, which may increase the ionic strength, and HNO3, to lower the pH. This allows the column 10 to react with the sorbent material, which may be a carbon-based sorbent material according to an embodiment of the present invention. 213Selective adsorption of Bi may occur. 225 The eluent containing Ac, HNO3 and NaNO3 may be removed through the outlet of column 10.

[0093] Step 2: Then, a small amount of a solution containing HNO3 and NaNO3 is applied, for example through an inlet, 213 Bi remains adsorbed 225 Ac is washed out of column 10. The eluents of steps 1 and 2 may be regenerated for use in the mixture in step 1 of a subsequent cycle, optionally after evaporation of the solvent of the eluent of step 2, thereby reducing waste products in the process.

[0094] Step 3: By introducing an eluent (i.e., removal solution) containing NaCl, NaCl or HCl having an ionic strength lower than that used for the adsorption process 1 through the inlet; 213 In fact, small masses of Bi may be eluted from high ionic strength solutions. 225 When Ac was also adsorbed onto column 10, 213 When eluting Bi, 225 It also becomes difficult to elute Ac. 213 The Bi-containing eluent may be collected through the outlet of the column 10, thereby recovering the daughter radionuclide. 213 Bi as the parent radionuclide 225 It was separated from Ac.

[0095] Step 4: To reuse column 10, remove any Cl on the column, for example by washing column 10 with HO or 0.1 M NH.HO. - or I - The ions may be eluted (ie, removed).

[0096] To further ensure the elution of high purity Bi (preferably because there can be no Ac in the eluent), a second column 20 (guard column) containing a sorbent material (e.g. AG MP-50 or Ac resin) with a higher affinity for the parent radionuclide than for the daughter nuclide may be introduced. The presence of the second column 20 213 The separation time of Bi does not need to be increased. 225 Ac / 213 An example of a Bi separation system is shown in Figure 7B. The arrows and numbers refer to the same method steps as described above with respect to Figure 7A. Here, in step 3 213 An eluent (i.e., removal solution) containing Bi may be passed from the outlet of column 10 to the inlet of second column 20. For example, the outlet of column 10 may be fluidly connected to the inlet of second column 20. The daughter radionuclides may then be eluted from second column 20, for example, via the outlet of second column 20, after allowing interaction between the sorbent material of the second column and any remaining parent radionuclides in the removal solution.

[0097] The carbon-based adsorbent materials of several of Examples 1-7 above were characterized using elemental analysis to determine the carbon, sulfur, and oxygen content of each material, and the results are summarized in Table A below. [Table 1]

[0098] In the above Examples 1-7, various adsorbent materials combined with the mixture were used. The present invention is of course not limited to these examples. Indeed, various optional technical features may be used to provide good properties to the carbon-based adsorbent material, as described elsewhere herein.

[0099] Below, examples of carbon-based sorbent materials are provided for future use in direct radionuclide separation systems. In the direct radionuclide separation systems, the parent (in the following examples, instead of the parent radionuclide, i.e., La) is added to the carbon-based sorbent material. 3+) and the daughter radionuclide (Bi 3+ ) from the carbon-based adsorbent material. Then, the daughter radionuclide (Bi in the following example) is adsorbed. 3+ ) is selectively desorbed.

[0100] Example 8 In this example, the adsorbent material included HDEHP-AC.

[0101] Bias ratios for HDEHP-AC for various S / L ratios where S is the amount of adsorbent material in milligrams and L is the amount of the mixture in milliliters. 3+ and La 3+ K d Reference is now made to FIG. 8A, which shows the La 3+ and Bi 3+ The effect of the amount of sorbent material (S) (in mg) over the amount (in mL) of the mixture (L) (i.e., a mixture of parent and daughter radionuclides) on the partition coefficient of La is shown. Here, the mixture is 10 μmol / L La 3+ and 10 μmol / L Bi 3+ The experiments were carried out at pH 2, 24 hours contact time and room temperature. The amount of adsorbent material was 30-400 mg and the amount of the mixture was 10 mL. The experiments were carried out at pH 2, 24 hours contact time and room temperature. Bis(OH)+HDEHP-AC for various concentrations of NaI in Example 6 3+ and La 3+ Reference is further made to FIG. 6B, which is a plot of D(%) of La from HDEHP-modified activated carbon. 3+ and Bi 3+ The effect of NaI concentration and the concentration of the mixture on the desorption rate of La on HDEHP-AC is shown. 3+ Referring to FIG. 8B, which shows the desorption rate of Bi 3+ After desorbing from the surface of the adsorbent, various volumes of concentrated nitric acid were added to the tube to measure the amount of La 3+ Wash and La 3+ ( 225The concentration of nitric acid during the desorption process ranges from 0.1 to 0.3 mol / L. 3+ and La 3+ See FIG. 8C, which shows the adsorption rate of the parent and daughter radionuclides. Here, the mixture of parent and daughter radionuclides is 10 μmol / L La 3+ and 10 μmol / L Bi 3+ The concentration of NaNO3 for the mixture ranged from 0.1 to 0.5 mol / L.

[0102] Combined with Figure 6A, pH>pK a In (1.47), La 3+ It can be observed that the adsorption capacity for La increases with increasing pH. 3+ The adsorption of Bi was observed using a NaI solution at pH 2 without affecting the adsorption of 3+ In fact, I - and Bi 3+ This may result in strong complex formation with La, which may then cause desorption. 3+ remains adsorbed on the carbon-based adsorbent material, I - and La 3+ There appears to be no complexation with

[0103] Combined with Figure 8B, the subsequent use of an acid solution (e.g., 0.2-0.3 mol / L HNO3) 225 Ac is eluted to reduce radiolytic damage to the column. The pH is then increased and the resulting 225 Ac can be used again. The salt concentration should not have a high effect on the adsorption process according to the effect of ionic strength. Correspondingly, an alkaline solution should be added to 225 The pH of the Ac solution can be increased to enhance the adsorption capacity of the adsorbent, which leads to an increase in ionic strength. Here, the effect of NaNO3 concentration was investigated to investigate the effect of ionic strength on the adsorption performance of HDEHP-AC. Figure 8C shows that the increase in the concentration of La with increasing NaNO3 concentration from 0.05 to 0.5 mol / L 3+ Kd This shows that the value gradually decreases. 3+ This is because the electrostatic attraction between La and HDEHP-AC weakens with increasing ionic strength. 3+ The removal rate of La was still over 90% in 0.5 mol / L NaNO3 solution, which indicates that HDEHP-AC is capable of removing La in a relatively high ionic strength solution. 3+ This shows that it still has a relatively good affinity for Bi 3+ The equilibrium concentration for Bi is below the lower detection limit of ICP-MS, and therefore 3+ K d The values ​​are still very high in the entire range, which is because AC-P is Bi 3+ This was attributed to the formation of inner-sphere complexes (Bi-OH / Bi=O) on HDEHP-AC.

[0104] Example 9: General principle of direct generators Directly According to an Embodiment of the Present Invention 225 Ac / 213 Please refer to FIG. 9, which is a schematic of the conceptual design and process flow for a Bi separation system. This example specifically relates to 213 Bi 225 Although it is for separation from Ac, separation of other daughter radionuclides from other parent radionuclides may be performed in similar systems according to embodiments of the present invention. The arrows showing the direction of flow of the fluids with the respective numbers (e.g. mixture / eluent / removal solution / ...) refer to the following method steps according to embodiments of the present invention.

[0105] Step 0 (preparation stage): The carbon-based adsorbent material may be conditioned with HNO3 (eg, at a concentration of at least 0.01 M). 225 Ac and 213 The mixture (ie, a mixture of parent and daughter radionuclides) may be prepared using HNO3 containing Bi (eg, >0.01M).

[0106] Step 1: The mixture may be introduced into column 10, for example, through an inlet. 225 Ac and 213 Both Bi and Mg may be adsorbed onto the adsorbent material of column 10.

[0107] Step 2: 213 To elute Bi, an eluent containing NaI (e.g., at least 0.45 M) and HNO3 (e.g., 0.01 M) may be introduced into column 10. That is, an eluent with a high ionic strength may increase the selectivity of the adsorbent material.

[0108] Step 3: To extend the life of the column 10, use HNO3 (e.g., a solution containing HNO3 at a concentration of 0.1 to 0.5 M). 225 Ac can be eluted. 225 By removing Ac, 225 The contact time between Ac and the carbon-based adsorbent material may be reduced.

[0109] Step 4: The amine obtained in step 3 225 The pH of the Ac solution is preferably at least 2. 225 The Ac solution may be reused in step 0 of the next cycle to form the mixture.

[0110] It will be appreciated that while preferred embodiments, specific constructions and configurations, and materials for the apparatus of the present invention are discussed herein, various changes or modifications in form and detail may be made without departing from the scope of the invention. For example, any means given above merely represent procedures that may be used. Steps may be added / removed to / from the methods described within the scope of the invention.

[0111] Example 10 For illustration, an example is given of how spherical carbon materials can be synthesized, but the embodiments are not limited thereto. In this example, cellulose beads were pyrolyzed at 400°C, and then a spherical sulfonated carbon material was produced through a sulfonation process. The sulfonation temperature and sulfonation time were 150°C and 180 minutes, respectively. See FIG. 10A, which is an illustration of the synthesis process. The SEM image in FIG. 10A shows that spherical carbonized cellulose beads were successfully synthesized. This example shows a method for synthesizing spherical carbon materials and spherical sulfonated carbon materials.

[0112] The adsorbent material, sulfonated carbonized cellulose beads, was sulfonated at a temperature of 150° C. 3+ and La 3+ K at various pH values d Reference is now made to FIG. 10B, which shows a graph of La 3+ and Bi 3+ Figure 10B shows the effect of pH on the adsorption rate of sulfonated carbonized cellulose beads for La. In the experiments performed for the results shown in Figure 10B, the mixture of parent and daughter radionuclides was diluted with 10 μmol / L La 3+ and 10 μmol / L Bi 3+ The amount of adsorbent material was 30 mg, the volume of the mixture was 10 mL, and the contact time was 24 hours at room temperature.

[0113] To further illustrate, but not to limit the invention, an experimental separation example is provided below. 225 Ac / 213 A Bi column was prepared. The 5 mL starting solution was prepared with 200 kBq of 225 The column was washed with H2O (10 mL) and then with 0.01 mol / L HNO3 solution (2 mL). After that, the column was washed with HO (10 mL) and then with 0.01 mol / L HNO3 solution (2 mL). 225Ac solution (5 mL) was passed through the column at an adsorption flow rate of 1.4 ± 0.1 mL / min. Afterwards, 1 mL of 0.02 mol / L HNO3 + 3 mol / L NaNO3 solution was used to wash the Falcon tube, then 2.5 mL of 0.02 mol / L HNO3 + 3 mol / L NaNO3 solution was used to wash the column-100. Finally, 1 mL of 1 mol / L HCl solution was used at an elution flow rate of 1.4 ± 0.1 mL / min. 213 Bi was eluted. 225 Ac impurity was 0.03±0.01% (at the end of separation 225 Ac: 213 The total separation time was 6.5±0.3 min. 213 The Bi yield was 94±3%.

Claims

1. ２１３ Bi daughter radionuclides ２２５ 1. A radionuclide separation system for separating Ac from its parent radionuclide, comprising: The above ２２５ an inlet for loading the column (10) with a liquid solution containing the Ac parent radionuclide; - At different moments in time ２２５ Ac parent radionuclide and / or ２１３ To enable selective desorption of Bi daughter radionuclides, ２２５ Ac parent radionuclide and ２１３ said column (10) comprising an adsorbent material capable of interacting with Bi daughter radionuclides; The above ２２５ Ac parent radionuclide and ２１３ Based on the selective desorption of Bi daughter radionuclides, ２１３ An outlet for selectively obtaining Bi daughter radionuclides; Equipped with The adsorbent material is a carbon-based adsorbent material. the carbonaceous adsorbent material is an inorganic carbonaceous adsorbent material; or The carbon-based adsorbent material is pyrolyzed polymers or polysaccharides, and / or Activated carbon, carbon nitride, graphitic carbon nitride, graphite and carbon molecular sieves including one or more of: Radionuclide separation system.

2. 10. The radionuclide separation system of claim 1, wherein the carbon-based sorbent material comprises an active material along with one or more compounds that include one or more functional groups.

3. The one or more functional groups are one or more oxygen-containing groups, and / or one or more sulfur-containing groups, and / or one or more phosphorus-containing groups 2. The radionuclide separation system of claim 1, wherein the radionuclide separation system is selected from the group consisting of:

4. 10. The radionuclide separation system of claim 1, wherein the carbon-based sorbent material is formed into beads, or the carbon-based sorbent material is provided as beads, tubular structures, honeycombs, or 3D printed monoliths.

5. 2. The radionuclide separation system of claim 1, wherein said carbon-based adsorbent material is formed into beads having a size between 5 μm and 1 mm.

6. The surface area of ​​the adsorbent material is 100 m ２ 10. The radionuclide separation system of claim 1, wherein the Rf is less than 100 / g.

7. 10. The radionuclide separation system of claim 1, wherein the carbon-based adsorbent material has a H / C molar ratio of less than 1.

8. The radionuclide separation system is a direct radionuclide separation system, and the carbon-based sorbent material is ２２５ 10. The radionuclide separation system of claim 1, having a strong affinity for both the Ac parent radionuclide and said daughter radionuclide.

9. The radionuclide separation system is an inverted radionuclide separation system, and the carbon-based sorbent material is ２２５ 10. The radionuclide separation system of claim 1, configured to have a higher affinity for the daughter radionuclide than for the Ac parent radionuclide.

10. 10. The radionuclide separation system of claim 9, wherein the carbon-based sorbent material comprises one or more of a phosphate group, a carbonyl, a hydroxyl group, or a carboxylic acid group.

11. ・ ２２５ Ac parent radionuclide and ２１３ loading the mixture with the Bi daughter radionuclide into a column (10) containing a carbon-based adsorbent material, the carbonaceous adsorbent material is an inorganic carbonaceous adsorbent material; or The carbon-based adsorbent material is pyrolyzed polymers or polysaccharides (e.g., cellulose, cellulose derivatives, starches, or phenolic resins), and / or Activated carbon, carbon nitride, graphitic carbon nitride, graphite and carbon molecular sieves and The adsorbent material is ２２５ Ac parent radionuclide and ２１３ a process for selectively interacting with Bi daughter radionuclides, the adsorbent material comprising: ２２５ Ac parent radionuclide and ２１３ To enable selective desorption of Bi daughter radionuclides, ２２５ Ac parent radionuclide and ２１３ having an affinity for interacting with a Bi daughter radionuclide; The above ２１３ To selectively obtain a Bi daughter radionuclide, after the interaction, ２２５ Ac parent radionuclide and ２１３ Selectively desorbing Bi daughter radionuclides; Including, Methods for separating radionuclides.

12. The adsorbent material is ２２５ The adsorbent material is ２１３ The above-mentioned radioactive nuclides are more ２２５ configured to have a high affinity for the Ac parent radionuclide; The step of selectively obtaining the daughter radionuclide comprises: ２２５ After the Ac parent radionuclide is bound to the adsorbent material, the adsorbent material is eluted with an eluent having a pH of at least 1. ２１３ 12. The method of claim 11, comprising eluting Bi daughter radionuclides from the column (10).

13. The adsorbent material is ２１３ to bind to the Bi daughter radionuclide. ２２５ Ac rather than the parent radionuclide ２１３ configured to have a high affinity for Bi daughter radionuclides; The aforementioned ２１３ The step of selectively obtaining the Bi daughter radionuclide comprises washing the column (10) and then ２１３ removing Bi daughter radionuclides from said column (10) into a removal solution; The method of claim 11.

14. The removal solution ２１３ The above-mentioned radioactive nuclides are more ２２５ A second column (20) containing an adsorbent material having a high affinity for the Ac parent radionuclide is further added, and the adsorbent material (20) of the second column and the remaining radioactive material in the removal solution are separated. ２２５ After allowing interaction with the Ac parent radionuclide, ２１３ 14. The method of claim 13, wherein Bi daughter radionuclides are eluted from the second column (20).

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