RADIONUCLIDE GENERATION

Abstract

A radionuclide separating system for separating a .sup.213Bi daughter radionuclide from a .sup.225Ac parent radionuclide, the radionuclide separating system comprising: an inlet for loading a liquid solution comprising the .sup.225Ac parent radionuclide onto a column; the column comprising a sorbent material wherein the sorbent material is capable of interacting with the .sup.225Ac parent radionuclide and .sup.213Bi daughter radionuclide so as to allow selective desorption of the .sup.225Ac parent radionuclide and/or the .sup.213Bi daughter radionuclide at a different moment in time; and an outlet for selectively obtaining the .sup.213Bi daughter radionuclide based on the selective desorption of the .sup.225Ac parent radionuclide and the .sup.213Bi daughter radionuclide, wherein the sorbent material is a carbon-based sorbent material.

Claims

1.-15. (canceled)

16. A radionuclide separating system for separating a .sup.213Bi daughter radionuclide from an .sup.225Ac parent radionuclide, the radionuclide separating system comprising: an inlet for loading a liquid solution comprising the .sup.225Ac parent radionuclide onto a column, the column comprising a sorbent material wherein the sorbent material is capable of interacting with the .sup.225Ac parent radionuclide and .sup.213Bi daughter radionuclide so as to allow selective desorption of the .sup.225Ac parent radionuclide and/or the .sup.213Bi daughter radionuclide at a different moment in time, and an outlet for selectively obtaining said .sup.213Bi daughter radionuclide based on said selective desorption of the .sup.225Ac parent radionuclide and the .sup.213Bi daughter radionuclide, wherein the sorbent material is a carbon-based sorbent material.

17. The radionuclide separating system according to claim 16, wherein the carbon-based sorbent material comprises an active material with one or more compounds containing one or more functional groups.

18. The radionuclide separating system according to claim 16, wherein the one or more functional groups are selected from: one or more oxygen containing groups; and/or one or more sulfur containing groups; and/or one or more phosphorous containing groups.

19. The radionuclide separating system according to claim 16, wherein the carbon-based sorbent material comprises one or more of: a pyrolyzed polymer or a polysaccharide; and/or an activated carbon, a carbon nitride, a graphitic carbon nitride, a graphite and a carbon molecular sieve.

20. The radionuclide separating system according to claim 16, wherein the carbon-based sorbent material is shaped in beads or wherein the carbon-based sorbent material is provided as shell of beads, as a tubular structures, as honeycomb or as 3D printed monolith.

21. The radionuclide separating system according to claim 16, wherein the carbon-based sorbent material is shaped in beads having a size between 5 m and 1 mm.

22. The radionuclide separating system according to claim 16, wherein the surface area of the sorbent material is smaller than 100 m.sup.2/g.

23. The radionuclide separating system according to claim 16, wherein the H/C molar ratio of the carbon-based sorbent material is lower than 1.

24. The radionuclide separating system according to claim 16, wherein the radionuclide separating system is a direct radionuclide separating system, the carbon-based sorbent material having a strong affinity for both the .sup.225Ac parent radionuclide and the daughter radionuclide, so as to selectively desorb the daughter radionuclide.

25. The radionuclide separating system according to claim 16, wherein the radionuclide separating system is an inverse radionuclide separating system, the carbon-based sorbent material being adapted for having a higher affinity for the daughter radionuclide rather than to the .sup.225Ac parent radionuclide.

26. The radionuclide separating system according to claim 25, wherein the carbon-based sorbent material comprises one or more of a phosphate group, carbonyl, a hydroxyl group or a carboxylic acid.

27. A method for separating radionuclides, the method comprising: loading a mixture of a .sup.225Ac parent radionuclide and a .sup.213Bi daughter radionuclide to a column comprising a carbon-based sorbent material, allowing the sorbent material to selectively interact with the .sup.225Ac parent radionuclide and the .sup.213Bi daughter radionuclide, the sorbent material having affinity for interacting with the .sup.225Ac parent radionuclide and .sup.213Bi daughter radionuclide so as to allow selective desorption of the .sup.225Ac parent radionuclide and the .sup.213Bi daughter radionuclide, and selectively desorbing the .sup.225Ac parent radionuclide and the .sup.213Bi daughter radionuclide after said interaction, so as to selectively obtain the .sup.213Bi daughter radionuclide.

28. The method according to claim 27, wherein the sorbent material is adapted so that the sorbent material has a higher affinity for the .sup.225Ac parent radionuclide than the .sup.213Bi daughter radionuclide so as to bind the .sup.225Ac parent radionuclide, wherein said selectively obtaining the daughter radionuclide comprises, eluting the .sup.213Bi daughter radionuclide from the column using an eluent having a pH of at least 1 after the .sup.225Ac parent radionuclide was bound to the sorbent material.

29. The method according to claim 27, wherein the sorbent material is adapted so that the sorbent material has a higher affinity for the .sup.213Bi daughter radionuclide than the .sup.225Ac parent radionuclide so as to bind the .sup.213Bi daughter radionuclide, wherein said selectively obtaining the .sup.213Bi daughter radionuclide comprises rinsing the column, and thereafter stripping the .sup.213Bi daughter radionuclide from the column into a strip solution.

30. The method according to claim 29, wherein the strip solution is further added to a second column having a sorbent material with higher affinity for the .sup.225Ac parent radionuclide than for the .sup.213Bi daughter radionuclide and eluting the .sup.213Bi daughter radionuclide from the second column, after interaction between the sorbent material of the second column and remaining .sup.225Ac parent radionuclide in the strip solution was allowed.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0052] FIG. 1A is a diagram of the K.sub.d, at a range of pH values, for La.sup.3+ and Bi.sup.3+ between the solvent and sulfonated Norit CA1, sulfonated at a temperature of 80 C., in accordance with embodiments of the present invention.

[0053] FIG. 1B is a diagram of the K.sub.d, at a range of pH values, for La.sup.3+ and Bi.sup.3+ between the solvent and sulfonated Norit CA1, sulfonated at a temperature of 150 C., in accordance with embodiments of the present invention.

[0054] FIGS. 1C and 1D are plots of the K.sub.d as a function of an ionic strength of a mixture of parent radionuclides and daughter radionuclides applied to sulfonated Norit CA1, sulfonated at a temperature of 150 C., at a pH of 2 and 1, respectively, in accordance with embodiments of the present invention.

[0055] FIG. 1E is a diagram of the desorption percentage D (%) of La.sup.3+ and Bi.sup.3+ from sulfonated Norit CA1, sulfonated at a sulfonation temperature of 150 C.

[0056] FIGS. 1F and 1G are diagrams of the K.sub.d, at pH 2 and 1, respectively, for La.sup.3+ and Bi.sup.3+ between the solvent and sulfonated Norit CA1, sulfonated at a temperature of 150 C., after receiving dose from .sup.60Co.

[0057] FIGS. 2A and 2B are diagrams of the K.sub.d, at a range of pH values, for Bi.sup.3+ and La.sup.3+ with respect to graphitized carbon black (Carbopack X) and sulfonated graphitized carbon black, respectively.

[0058] FIGS. 3A and 3B are diagrams of the K.sub.d, at a range of pH values, of Bi.sup.3+ and La.sup.3+ on Carboxen 572 and sulfonated Carboxen 572, respectively.

[0059] FIG. 4A is a diagram of the K.sub.d of La.sup.3+ and Bi.sup.3+ with respect to sulfonated carbonized methyl cellulose, carbonized at a range of temperatures, and at a pH of 2.

[0060] FIG. 4B is a diagram of the R (%) of La.sup.3+ or Bi.sup.3+ with respect to sulfonated carbonized methyl cellulose, carbonized at a range of temperatures, and at a pH of 2.

[0061] FIG. 4C is a diagram of the K.sub.d of La.sup.3+ or Bi.sup.3+ with respect to sulfonated carbonized methyl cellulose, carbonized at a range of temperatures, and at a pH of 1.

[0062] FIG. 4D is a diagram of the R (%) of La.sup.3+ or Bi.sup.3+ with respect to sulfonated carbonized methyl cellulose, carbonized at a range of temperatures, and at a pH of 1.

[0063] FIG. 5A is a diagram of the R (%) at a range of pH values for Bi.sup.3+ and La.sup.3+, with respect to the sorbent material activated carbon Norit CA1, in accordance with embodiments of the present invention.

[0064] FIG. 5B is a diagram of the high-resolution XPS oxygen is spectrum of Norit CA1.

[0065] FIGS. 6A and 6B are diagrams of the R (%) at a range of pH values, and the D (%) for different concentrations of NaI at pH 2, respectively, for Bi.sup.3+ and La.sup.3+, with respect to the sorbent material HDEHP-AC, in accordance with embodiments of the present invention.

[0066] FIG. 7A is a schematic representation of a conceptual design of, and a process flow for, an inverse .sup.225Ac/.sup.213Bi separating system, in accordance with embodiments of the present invention.

[0067] FIG. 7B is a schematic representation of a conceptual design of, and a process flow for, an inverse .sup.225Ac/.sup.213Bi separating system with a guard column.

[0068] FIG. 8A is a diagram of the K.sub.d of Bi.sup.3+ and La.sup.3+ with respect to HDEHP-AC, for a range of ratios of S/L, with S the amount of sorbent material in milligram, and L the amount of the mixture in millilitre.

[0069] FIG. 8B is a diagram of the D (%) of Bi.sup.3+ and La.sup.3+ with respect to HDEHP-AC, for a range of concentrations of HNO.sub.3.

[0070] FIG. 8C is a diagram of the R (%) of Bi.sup.3+ and La.sup.3+ with respect to HDEHP-AC, for a range of concentrations of NaNO.sub.3.

[0071] FIG. 9 is a schematic representation of a conceptual design of, and a process flow for, a direct .sup.225Ac/.sup.213Bi separating system, in accordance with embodiments of the present invention.

[0072] FIG. 10A is a diagram of SEM images of cellulose beads, carbonized cellulose beads, and sulfonated carbonized cellulose beads.

[0073] FIG. 10B is a diagram of the K.sub.d, at a range of pH values, of Bi.sup.3+ and La.sup.3+ on sulfonated carbonized cellulose beads.

[0074] FIG. 11 illustrates two systems for separating radionuclides, according to embodiments of the present invention.

[0075] In the different figures, the same reference signs refer to the same or analogous elements.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0076] 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 and not drawn on scale for illustrative purposes. The dimensions and the relative dimensions do not correspond to actual reductions to practice of the invention.

[0077] Furthermore, the terms first, second, third and the like in the description and in the claims, are used for distinguishing between similar elements and not necessarily for describing a sequence, either temporally, spatially, in 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 are capable of operation in other sequences than described or illustrated herein.

[0078] Moreover, the terms top, bottom, over, under and the like in the description and the claims are used for descriptive purposes and not necessarily for describing relative positions. It is to be understood that the terms so used are interchangeable under appropriate circumstances and that the embodiments of the invention described herein are capable of operation in other orientations than described or illustrated herein.

[0079] It is to be noticed that the term comprising, used in the claims, should not be interpreted as being restricted to the means listed thereafter; it does not exclude other elements or steps. It is thus to be interpreted as specifying the presence of the stated features, integers, steps or components as referred to, but does not preclude the presence or addition of one or more other features, integers, steps or components, or groups thereof. The term comprising therefore covers the situation where only the stated features are present and the situation where these features and one or more other features are present. The word comprising according to the invention therefore also includes as one embodiment that no further components are present. Thus, the scope of the expression a device comprising means A and B should not be interpreted as being limited to devices consisting only of components A and B. It means that with respect to the present invention, the only relevant components of the device are A and B.

[0080] Similarly, it is to be noticed that the term coupled should not be interpreted as being restricted to direct connections only. 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 expression a device A coupled to a device B should not be limited to devices or systems wherein an output of device A is directly connected to an input of device B. It means that there exists a path between an output of A and an input of B which may be a path including 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 yet still co-operate or interact with each other.

[0081] Reference throughout this specification to one embodiment or an embodiment means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases in one embodiment or in an embodiment in various places throughout this specification are not necessarily all referring 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.

[0082] Similarly, it should be appreciated that in the description of exemplary embodiments of the invention, various features of the invention are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of one or more of the various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the claimed invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects lie in less than all features of a single foregoing disclosed embodiment. Thus, the claims following the detailed description are hereby expressly incorporated into this detailed description, with each claim standing on its own as a separate embodiment of this invention.

[0083] Furthermore, while some embodiments described herein include some but not other features included in other embodiments, combinations of features of different embodiments are meant to be within the scope of the invention, and form different embodiments, as would be understood by those in the art. For example, in the following claims, any of the claimed embodiments can be used in any combination.

[0084] Furthermore, some of the embodiments are described herein as a method or combination of elements of a method that can be implemented by a processor of a computer system or by other means of carrying out the function. Thus, a processor with the necessary instructions for carrying out such a method or element of a method forms a means for carrying out the method or element of a method. Furthermore, an element described herein of an apparatus embodiment is an example of a means for carrying out the function performed by the element for the purpose of carrying out the invention.

[0085] In the description provided herein, numerous specific details are set forth. However, it is understood that embodiments of the 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.

[0086] The following terms are provided solely to aid in the understanding of the invention.

[0087] As used in the context of the present invention, grafting functional groups, means that the chemical species are covalently bonded onto the solid surface, e.g., the surface of a sorbent material. As used in the context of the present invention, impregnation of functional groups means that the chemical species are physically distributed in the internal surface of the porous material.

[0088] 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.

[0089] In a first aspect, the present invention relates to a radionuclide separating system for separating a daughter radionuclide from a parent radionuclide. The radionuclide separating system comprises an inlet for loading a liquid solution comprising the parent radionuclide onto a column. The radionuclide separating system further comprises the column, which comprises a sorbent material wherein the sorbent material is capable of interacting with the parent radionuclide and daughter radionuclide so as to allow selective desorption of the parent radionuclide and/or the daughter radionuclide at a different moment in time. Herein, the sorbent material is a carbon-based sorbent material. The radionuclide separating system further comprises an outlet for selectively obtaining said daughter radionuclide based on said selective desorption of the parent radionuclide and the daughter radionuclide.

[0090] In a second aspect, the present invention relates to a method for separating radionuclides, the method comprising: loading a mixture of a parent radionuclide and a daughter radionuclide to a column comprising a carbon-based sorbent material; allowing the sorbent material to selectively interact with the parent radionuclide and the daughter radionuclide, the sorbent material having an affinity for interacting with the parent radionuclide and daughter radionuclide so as to allow selective desorption of the parent radionuclide and/or the daughter radionuclide; and selectively desorbing the parent radionuclide and the daughter radionuclide after said interaction, so as to selectively obtain the daughter radionuclide.

[0091] By way of illustration, embodiments not being limited thereto, a schematic overview of a direct and inverse radionuclide separating system is shown in FIG. 11.

[0092] Several carbon-based sorbent materials, both for use in an inverse radionuclide separating system, and for use in a direct radionuclide separating system, in accordance with embodiments of the present invention, have been prepared and tested, as described below. Herein, although La.sup.3+ (as a substitute for a parent radionuclide) and Bi.sup.3+ (as daughter radionuclide) are used in the exemplary mixture, comprising water as a solvent, it is to be understood that, in particular, other parent and/or daughter radionuclides could be used as well. In particular, La.sup.3+ may be assumed to be replaceable by Ac.sup.3+ without considerably changing the results obtained and described below.

[0093] In the following examples, reference is made to R (%), which is a removal percentage. Furthermore, reference is made to D (%), which is a desorption percentage. Finally, reference is made to K.sub.d (mg/L), which is a distribution coefficient, defined as the concentration ratio of a chemical between two media (e.g., between the sorbent material and the mixture of the parent radionuclide and the daughter radionuclide) at equilibrium. The removal percentage R (%), distribution coefficient K.sub.d (mL/g), and desorption percentage D (%) may be calculated as follows:

[00001]$R\left(\%\right)=\frac{C_0-C_e}{C_0}100\%D\left(\%\right)=\frac{n_{s1}-n_{s2}}{n_{s1}}100\%K_d\left(\%\right)=\frac{C_0-C_e}{C_0}\frac{V}{m}$

wherein m (g) is the mass of the adsorbents (i.e., the sorbent material). V (mL) is liquid phase volumes in the adsorption process, and Co (mol/L) and C.sub.e (mol/L) represent the initial concentration and equilibrium concentration of La.sup.3+ or Bi.sup.3+ in the adsorption process, respectively. n.sub.s1 (mol) and n.sub.s2 (mol) represent the amount of La.sup.3+ or Bi.sup.3+ adsorption on the sorbent after the adsorption process and desorption process, respectively.

[0094] In what follows, examples are provided of carbon-based sorbent materials for use in an inverse radionuclide separating system. In the inverse radionuclide separating system, there is first selective adsorption of the daughter radionuclide (in the following examples, Bi.sup.3+) over the parent radionuclide (in the following examples, a substitute for the parent radionuclide, i.e., La.sup.3+) on the sorbent material. Next, desorption of the daughter radionuclide is performed from the sorbent material.

Example 1

[0095] In this example, the sorbent material is activated carbon Norit CA1, with additional grafting by H.sub.2SO.sub.4 or HNO.sub.3 treatment. Herein, the grafting results in an increase in oxygen content (both for H.sub.2SO.sub.4 and HNO.sub.3 treatment), i.e., in the formation of carboxylic (and other) groups, and in an increase in sulphur content (for H.sub.2SO.sub.4 treatment), i.e., in the formation of sulphonic acid groups. For example, the sulfonated Norit CA1 (150 C.) was fabricated using concentrated H.sub.2SO.sub.4. Briefly, 15 g of Norit CA1 was mixed with 150 mL of concentrated sulfuric acid (95.0-98.0%) in a 500 mL round-bottomed flask and stirred for 10 min at room temperature. Then, the suspension was heated to 150 C. with continuous agitation and kept at that temperature for 3 h. After the suspension was cooled at room temperature, the obtained black products were filtered and intensively washed with deionized water until sulfate ions were no longer detected with barium chloride (addition of 5 drops of 1.0 M BaCl.sub.2 to 1 mL of filtrate). Finally, the sample was dried in an oven at 70 C. The prepared product was designated sulfonated Norit CA1 (150 C.).

[0096] The functional groups of sulfonated Norit CA1 (150 C.) were investigated by XPS. The two main oxygen environments could be assigned to OC (531.3 eV) and OC (533.1 eV), representing a potential mixture of hydroxyl, carbonyl and carboxylate functional groups. In addition, this lower binding energy component becomes sharper, and more intense, which can then be assigned to overlapping sulfate/sulfonate and carbonyl environments. The sulfur 2p spectrum of sulfonated Norit CA1 (150 C.) showed a mixture of two overlapping sulfur environments that we have tentatively assigned to a mixture of sulfonate or sulfate (S 2p3/2 at 168.5 eV) and a lower oxidation state species such as sulfite or sulfinic acids (167.5 eV).

[0097] Reference is made to FIG. 1A, which is a diagram of the K.sub.d, at a range of pH values, for La.sup.3+ and Bi.sup.3+ between the mixture, e.g., solvent (water), and sulfonated Norit CA1, sulfonated at a temperature of 80 C. Thereby, FIG. 1A indicates the effect of pH on the distribution coefficient of the sulfonated Norit CA1, sulfonated at a temperature of 80 C. Herein, the mixture of a parent radionuclide and a daughter radionuclide comprised 1.02 mol/L of La.sup.3+ and 0.57 mol/L of Bi.sup.3+. The amount of sorbent material was 20 mg and the amount of the mixture was 10 mL. The contact time was 24 h at room temperature. Further reference is made to FIG. 1B, which shows the effect of pH on the distribution coefficient for sulfonated Norit CA1, sulfonated at a temperature of 150 C., toward La.sup.3+ and Bi.sup.3+. Herein, the mixture of a parent radionuclide and a daughter radionuclide comprised 10 mol/L of La.sup.3+ and 10 mol/L of Bi.sup.3+. The amount of sorbent material was 10 mg and the amount of the mixture was 10 mL. The contact time was 24 h at room temperature. Further reference is made to FIGS. 1C and 1D, which shows the effect of ionic strength (e.g., NaNO.sub.3) of a mixture comprising La.sup.3+ or Bi.sup.3+, on the K.sub.d of said mixture with respect to sulfonated Norit CA1, sulfonated at a temperature of 150 C. Herein, the mixture of a parent radionuclide and a daughter radionuclide comprised 10 mol/L of La.sup.3+ and 10 mol/L of Bi.sup.3+. The amount of sorbent material was 10 mg and the amount of the mixture was 10 mL. Herein, the experiments for FIG. 1C were performed at a pH of 2, and those for FIG. 1D were performed at a pH of 1. It may be observed that higher selectivity in La.sup.3+/Bi.sup.3+ adsorption can be achieved by increasing ionic strength and decreasing pH. The explanation of this observation is that sulphonation leads to formation of oxygen-containing groups, which will participate in adsorption of both La.sup.3+ and Bi.sup.3+. As pH increases, both carboxylic and other groups, will become increasingly deprotonated, leading to more sorption sites (resulting in an increase in K.sub.d,Bi and K.sub.d,La). Additionally, the competition with H.sub.3O.sup.+ (present at higher concentrations at lower pH) is increased. Furthermore, increasing the ionic strength may further result in less interaction of the carboxylic/sulphonic groups with La.sup.3+.

[0098] FIG. 1E shows the desorption percent of La.sup.3+ and Bi.sup.3+ from the sulfonated Norit CA1 (150 C.). With decreasing pH and increasing Cl.sup. concentration, desorption efficiency for La.sup.3+ and Bi.sup.3+ increased quickly at first then slightly, reaching 100% with 3 mol/L HCl elutions. The desorption mechanism is mainly ascribed to ion exchange selectivity reversal between the protons (H.sup.+) and La.sup.3+/Bi.sup.3+ under the acid environment and the complexation of Bi.sup.3+ and Cl.sup.. Herein, the mixture of starting solution comprised 10 mol/L of La.sup.3+ and 10 mol/L of Bi.sup.3+ in a 10 mL solution. The amount of sorbent was 20 mg. Then different volumes (0.084-3.333 mL) of 12.0 mol/L HCl stock solution were added into to achieve an HCl concentration range of 0.1-3.0 mol/L.

[0099] The radiation stability of sulfonated Norit CA1 (150 C.) was also investigated by exposing the sorbent to radiation and investigating the impact on the sorption performance. Briefly, the 200 mg sulfonated Norit CA1 (150 C.) was mixed with 2 mL of 1 M HCl solutions into 4 mL glass vials and irradiated by .sup.60Co. The received doses were from 0.5 to 11 MGy. References samples in 2 mL of 1 M HCl solutions without radiation treatment were also done. Finally, the samples were washed and dried in an oven and then used to study the sorption properties. Herein, the mixture of solution comprised 10 mol/L of La.sup.3+ and 10 mol/L of Bi.sup.3+. The amount of sorbent material was 10 mg and the amount of the mixture was 10 mL. Herein, the experiments for FIG. 3H were performed at a pH of 2, and those for FIG. 31 were performed at a pH of 1. It may be observed that there may be no noticeable decreasing change of the sorption performance, indicating no apparent change for the number of sorption sites.

Example 2

[0100] In this example, the sorbent material comprised graphitized carbon black (Carbopack X) and sulfonated graphitized carbon black. Herein, the reaction conditions for the sulfonization are 5 g of Carbopack X in 50 mL 97% H.sub.2SO.sub.4 at 80 C. for 180 min, thereby forming the sulfonated graphitized carbon black, i.e., sulfonated Carbopack X.

[0101] Reference is made to FIG. 2, which is a diagram of the K.sub.d, at a range of pH values, for Bi.sup.3+ and La.sup.3+ between the solvent and the graphitized carbon black (Carbopack X) or sulfonated graphitized carbon black. As such, FIG. 2A shows the effect of pH on distribution coefficients of La.sup.3+ and Bi.sup.3+ with respect to Carbopack X. Further reference is made to FIG. 2B, which is a diagram of the K.sub.d, at a range of pH values, for Bi.sup.3+ and La.sup.3+ between the solvent and the sulfonated Carbopack X. As such, FIG. 2A shows the effect of pH on distribution coefficients of La.sup.3+ and Bi.sup.3+ with respect to sulfonated Carbopack X. In both cases, the mixture comprised 1.01 mol/L of La.sup.3+ and 0.57 mol/L of Bi.sup.3+. The amount of sorbent material was 20 mg and the amount of the mixture was 10 mL. The contact time was 24 h at room temperature. It may be observed that there is nearly no sorption of La.sup.3+, there is low capacity for Bi.sup.3+ (compared to activated carbon) due to insufficient functional groups, but there is selectivity towards Bi.sup.3+ over La.sup.3+. After sulfonation, the sorption capacity for Bi.sup.3+ increased. After sulfonation, it was observed that the content of sulfur and oxygen slowly increased. A similar explanation for these observations may be assumed as with respect to Example 1 above.

Example 3

[0102] In this example, the sorbent material is a Carbon Molecular Sieve [Carboxen 572]. Herein, sulfonated Carboxen 572 was synthesized using 2.5 g of Carboxen 572 in 25 mL of 97% H.sub.2SO.sub.4, at 150 C. for 240 min.

[0103] Reference is made to FIG. 3A, which is a diagram of the K.sub.d, at a range of pH values, of Bi.sup.3+ and La.sup.3+ between the solvent and Carboxen 572, showing the effect of pH on distribution coefficients of La.sup.3+ and Bi.sup.3+ on Carboxen 572. Further reference is made to FIG. 3B, which is a diagram of the K.sub.d, at a range of pH values, of Bi.sup.3+ and La.sup.3+ between the solvent and sulfonated Carboxen 572, thereby showing the effect of pH on the distribution coefficients of La.sup.3+ and Bi.sup.3+ with respect to sulfonated Carboxen 572. In both cases, a mixture of a parent radionuclide and a daughter radionuclide was used comprising a concentration of 1.0 mol/L of La.sup.3+ and of 1.0 mol/L of Bi.sup.3+. The amount of sorbent material was 25 mg, and the amount of the mixture was 10 mL. The contact time was 24 h at room temperature.

[0104] It may be observed that there is no sorption of La.sup.3+ for Carboxen 572. Furthermore, there is low capacity for Bi.sup.3+ and La.sup.3+ due to insufficient functional groups, but there is selectivity towards Bi.sup.3+ over La.sup.3+. After sulfonation, the sorption capacity for Bi.sup.3+ increased with the increase of sulfur and oxygen contents on the surface of sulfonated Carboxen 572. A similar explanation for these observations may be assumed as with respect to Example 2 above. A NaNO.sub.3 solution could be employed to avoid La.sup.3+ adsorption on sulfonated Carboxen 572, as was also observed in the results of Example 1.

Example 4

[0105] In this example, the sorbent material is sulfonated carbonized methyl cellulose (SCMC). Herein, the carbonized methyl cellulose is formed by carbonization of methyl cellulose at a range of temperatures. Below and in the figures, SCMC-[T] is used, wherein [T] indicates the temperature at which the methyl cellulose was carbonized. Herein, sulfonation was performed in 97% H.sub.2SO.sub.4, at 150 C. for 600 min.

[0106] Reference is made to FIG. 4A and FIG. 4C, which are diagrams of the K.sub.d of La.sup.3+ and Bi.sup.3+ with respect to sulfonated carbonized methyl cellulose, carbonized at a range of temperatures, and at a pH of 2 and 1, respectively. These diagrams show the effect of the carbonization temperature and pH on the adsorption coefficient of La.sup.3+ or Bi.sup.3+ on sulfonated carbonized methyl cellulose. Further reference is made to FIGS. 4B and 4D, which are diagrams of the R (%) of La.sup.3+ and Bi.sup.3+ with respect to sulfonated carbonized methyl cellulose, carbonized at a range of temperatures, and at a pH of 2 and 1, respectively. These diagrams showed the effect of the carbonization temperature on removal percentage of La.sup.3+ or Bi.sup.3+ on sulfonated carbonized methyl cellulose. For these experiments, the mixture of a parent radionuclide and a daughter radionuclide comprised 10 mol/L of La.sup.3+ or 10 mol/L of Bi.sup.3+. The amount of sorbent material was 10 mg, and the amount of the mixture was 10 mL. The contact time was 24 h at room temperature. It may be observed that some of the materials showed high sorption capacity for Bi.sup.3+ or La.sup.3+. The performance of SCMC-400 and SCMC-450 is definitively as good as the commercial ones (e.g., sulfonated Norit CA1). The sorption performance for sulfonated carbon materials with soft structures was better than for those with hard structures.

Example 5

[0107] In this example, the sorbent material is activated carbon Norit CA1 (without additional functionalization, e.g., through grafting). Reference is made to FIG. 5A, which is a diagram of the R (%) at a range of pH values for Bi.sup.3+ and La.sup.3+, with respect to the sorbent material activated carbon Norit CA1. FIG. 5A, thereby, indicated that the effect of pH on adsorption percentages of Norit CA1 towards La.sup.3+ and Bi.sup.3+. In the experiments performed for the results shown in FIG. 5A, the mixture of a parent radionuclide and a daughter radionuclide comprised 10 mol/L of La.sup.3+ and 10 mol/L of Bi.sup.3+. The amount of sorbent material was 10 mg and the amount of the mixture was 10 mL, and the contact time was 24 h at room temperature.

[0108] It may be observed that at pH1.0, a high selectivity in La.sup.3+/Bi.sup.3+ sorption may be achieved (i.e., no sorption capacity for La.sup.3+, and high removal percentages for Bi.sup.3+). An explanation for this observation may be found in that this kind of activated carbon has different kinds of functional groups on its surface, allowing different interaction mechanisms with La.sup.3+ and Bi.sup.3+. XPS oxygen is spectra for Norit CA1 was shown in FIG. 5B. The two main oxygen environments could be assigned to OC (531.3 eV) and OC (533.1 eV), representing a potential mixture of hydroxyl, carbonyl and carboxylate functional groups.

Example 6

[0109] In this example, the sorbent material comprised HDEHP-AC, i.e., bis(2-ethylhexyl)phosphate modified activated carbon. Bis(2-ethylhexyl)phosphate has the following chemical structure:

##STR00001##

[0110] Reference is made to FIG. 6A, which is a diagram of the R (%) at a range of pH values for Bi.sup.3+ and La.sup.3+, with respect to the sorbent material HDEHP-AC. Thereby, FIG. 6A indicated the effect of pH on adsorption (i.e., removal) percentages of HDEHP-AC towards La.sup.3+ and Bi.sup.3+. Results indicated that the adsorption capacity for La.sup.3+ was much more sensitive to pH in a short range from 2 to 1, while Bi.sup.3+ exhibited relatively less dependence during this pH range. The percent removal for La.sup.3+ decreased rapidly from 80% at pH 2 to 0 at pH 1. At pH 2, high amounts of La.sup.3+ ions were adsorbed on HDEHP-AC via electrostatic attraction, ascribed to the deprotonated PO.sub.4H groups from HDEHP (pK.sub.a1.47). At pH 1, there was nearly no adsorption capacity for La.sup.3+ because of the interference of H.sup.+ ions and the lack of electrostatic attraction between HDEHP-AC and La.sup.3+ ions. It was also indicated that La.sup.3+ would be much easier desorbed due to ion-exchange with H.sup.+ in an acidic solution when pH<pK.sub.a. Compared to La.sup.3+, at pH 1, the removal percentage for Bi.sup.3+ was still more than 90% due to the complexation of Bi.sup.3+ with PO and POH groups or hydrolysis of Bi.sup.3+ on the surface of HDEHP-AC. However, from pH 1 to pH 0.5, the removal percentage for Bi.sup.3+ decreased quickly from 93% to 37%; this is due to the electrostatic repulsion between Bi.sup.3+ and protonated functional groups, and the competitive adsorption of excess H.sup.+ ions. Based on the pH effect, one conclusion may be drawn that the HDEHP-AC can selectively uptake Bi.sup.3+ from La.sup.3+/Bi.sup.3+ mixture solution at low pH (e.g., pH 1). In summary, when the pH is at most 1.0, a high selectivity in La.sup.3+/Bi.sup.3+ sorption may be achieved (that is, nearly no sorption capacity for La.sup.3+, and high removal percentages for Bi).

[0111] Further reference is made to FIG. 6B, which is a diagram showing the D (%) for different concentrations of NaI with respect to the sorbent material HDEHP-AC. Results showed that the desorption percentage for Bi.sup.3+ was relatively higher at a high concentration of NaI solution at pH 2. Combined with the effect of pH, we may conclude that the NaI solution can be used to elute .sup.213Bi. Further, with the pH of elution decreasing, the .sup.213Bi may be increasing. Preferably, the pH of elution is at most 2.

[0112] Thereby, FIG. 6B shows the effect of elution concentration on desorption percentages of La.sup.3+ and Bi.sup.3+. For both examples, a mixture of a parent radionuclide and a daughter radionuclide was used comprising a concentration of La.sup.3+ of 10 mol/L and a concentration of Bi.sup.3+ of 10 mol/L. For FIG. 6A, the amount of sorbent material was 60 mg, the amount of the mixture was 30 mL, and the contact time (that is, between sorbent material and the mixture) was 24 h at room temperature, i.e., 25 C. For FIG. 6B, the amount of sorbent 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 h at room temperature.

Example 7: General Principles of the Inverse Generator

[0113] Reference is made to FIG. 7A, which is a schematic representation of a conceptual design of, and a process flow for, an inverse .sup.225Ac/.sup.213Bi separating system, illustrating more general principles in accordance with embodiments of the present invention. Although this example is specifically for separating .sup.213Bi from .sup.225Ac, separation of other daughter radionuclides from other parent radionuclides may be performed in the same or similar systems, in accordance with embodiments of the present invention. Arrows, indicating direction of fluid (e.g., mixture/eluent/stripping solution/ . . . ) flow, with respective numbers, refer to the following method steps, which are in accordance with embodiments of the present invention.

[0114] Step 0 (preparation phase, not indicated): Based on the density of active sites for .sup.225Ac and .sup.213Bi, the optimal ionic strength and pH range may be chosen. The column 10 is typically conditioned with HNO.sub.3 (e.g., 0.1 M), which may be introduced through an inlet of the column.

[0115] Step 1: Then, the mixture of a parent radionuclide and a daughter radionuclide, comprising .sup.225Ac (parent radionuclide) and .sup.213Bi (daughter radionuclide), is passed through the column 10, e.g., comprising introducing in the column 10 via an inlet. The mixture may further comprise, for example, NaNO.sub.3, which may increase the ionic strength, and HNO.sub.3, for reducing the pH. This may result in selective adsorption of .sup.213Bi on the sorbent material in the column 10, which is a carbon based sorbent material in accordance with embodiments of the present invention. An elution comprising .sup.225Ac, HNO.sub.3, and NaNO.sub.3 may be removed through an outlet of the column 10.

[0116] Step 2: Subsequently, a small volume of a solution containing HNO.sub.3 and NaNO.sub.3 would be applied, e.g., through the inlet, to rinse residual .sup.225Ac from the column 10, while .sup.213Bi remains adsorbed. The elutes of step 1 and 2, possibly after evaporation of the solvent of the elute of step 2, may be regenerated for use in the mixture in a step 1 of a subsequent cycle, thereby reducing waste of the process.

[0117] Step 3: .sup.213Bi may be eluted, by introducing through the inlet, an elution solution, i.e., strip solution, comprising NaCl, NaCl or HCl with lower ionic strength than that used for the sorption process 1. Indeed, if even a small mass of .sup.225Ac from the high ionic strength solution is sorbed onto the column 10, it would be also difficult to elute this .sup.225Ac when eluting the .sup.213Bi. The elute comprising .sup.213Bi may be collected through an outlet of the column 10, whereby the daughter radionuclide .sup.213Bi has been separated from the parent radionuclide .sup.225Ac.

[0118] Step 4: To reuse the column 10, any Cl.sup. or I.sup. ions on the column may be eluted, i.e., removed, by rinsing the column 10 with, for example, H.sub.2O or 0.1 M NH.sub.3.Math.H.sub.2O.

[0119] To further ensure high purity of the eluted Bi (as preferably no Ac may be present in the elution), a second column 20 (guard column) may be introduced, comprising a sorbent material with higher affinity for the parent radionuclide than for the daughter nuclide, e.g., AG MP-50 or Ac resin. The presence of the second column 20 may not increase the separation time for .sup.213Bi. An example of an inverse .sup.225Ac/.sup.213Bi separating system comprising the second column 20 is shown in FIG. 7B. The arrows and numbers refer to the same method steps as explained above with respect to FIG. 7A. Herein, in step 3, the elute comprising .sup.213Bi, i.e., a strip solution, may be passed on from the outlet of the column 10 to an inlet of the second column 20. For example, the outlet of the column 10 may be fluidically coupled to the inlet of the second column 20. Subsequently, after interaction between the sorbent material of the second column and remaining parent radionuclide in the strip solution was allowed, the daughter radionuclide may be eluted from the second column 20, e.g., via an outlet of the second column 20.

[0120] For several of the carbon-based sorbent materials of the above Examples 1 to 7, the characteristics of the sorbent materials have been analysed using elemental analysis, to determine the carbon, sulphur and oxygen content in the respective materials. The results are summarized below in Table A.

TABLE-US-00001 TABLE A Elemental analysis results H/C (molar Sorbent material N (%) C (%) H (%) S (%) O (%) P (%) ratio) HDEHP modified 0.19 82.83 3.13 <0.5 7.40 2.36 0.450 activated carbon Norit CA1 0.43 70.41 3.54 <0.5 15 0.555 Sulfonated Norit CA1 0.34 69.01 3.96 2.21 29.63 0.684 (150 C.) Carbopack X 0.17 99.33 0.00 0.16 0.27 0 Sulfonated Carbopack X 0.17 96.78 0.00 0.37 1.28 0 Carboxen 572 0.46 92.12 0.28 4.14 0.05 0.036 Sulfonated Carboxen 0.56 87.93 0.39 4.59 6.55 0.053 572 Carbonized methyl 0.00 84.41 3.63 <0.5 8.77 0.514 cellulose (pyrolysis temp.: 400 C.) (CMC-400) Sulfonated CMC-400 0.00 65.46 2.65 2.72 28.65 0.482 (SCMC-400) Carbonized methyl 0.10 89.31 2.69 <0.5 7.33 0.359 cellulose (pyrolysis temp.: 500 C.) (CMC-500) Sulfonated CMC-500 0.00 69.57 2.66 4.86 22.71 0.458 (SCMC-500) Carbonized methyl 0.34 92.10 1.30 <0.5 6.39 0.168 cellulose (pyrolysis temp.: 700 C.) (CMC-700) Sulfonated CMC-700 0.08 79.75 1.44 3.88 15.40 0.215 (SCMC-700)

[0121] In the above Examples 1 to 7, a range of sorbent materials, in combination with mixtures, were used. The present invention is, of course, not limited to these examples. Indeed, a range of optional technical features may be used to provide good properties to the sorbent material, as described elsewhere in this description.

[0122] In what follows, examples are provided of carbon-based sorbent materials for future use in a direct radionuclide separating system. In direct radionuclide separating system, there is first co-adsorption of the parent (in the following examples, a substitute for the parent radionuclide, i.e., La.sup.3+) and daughter radionuclide (in the following examples, Bi.sup.3+) on the sorbent material. Next, selective desorption of the daughter radionuclide (in the following examples, Bi.sup.3+) is performed from the sorbent material.

Example 8

[0123] In this example, the sorbent material comprised HDEHP-AC.

[0124] Reference is made to FIG. 8A, which is a diagram of the K.sub.d of Bi.sup.3+ and La.sup.3+ with respect to HDEHP-AC, for a range of ratios of S/L, with S the amount of sorbent material in milligram, and L the amount of the mixture in milliliter. Herein, the effect of the amount (in mg) of sorbent material (S) over the amount (in mL) of the mixture (L) (i.e., mixture of a parent radionuclide and a daughter radionuclide) is shown on the distribution coefficients of La.sup.3+ and Bi.sup.3+ with respect to HDEHP modified activated carbon. Herein, the mixture comprised 10 mol/L of La.sup.3+, and 10 mol/L of Bi.sup.3+. The experiments were performed at pH 2 with a contact time of 24 h at room temperature. The amount of sorbent material was 30-400 mg and the amount of the mixture was 10 mL. The experiments were performed at pH 2, with a contact time of 24 h, and at room temperature. Further reference is made to FIG. 6B in the example 6, which is a diagram of the D (%) of Bi.sup.3+ and La.sup.3+ with respect to HDEHP-AC, for a range of concentrations of NaI. Thereby, this diagram showed the effect of concentration of NaI, of the mixture on the desorption percentages of La.sup.3+ and Bi.sup.3+ from HDEHP modified activated carbon. Reference is made to FIG. 8B, which is a diagram of the desorption percentage of La.sup.3+ with respect to HDEHP-AC, after the Bi.sup.3+ desorbed from the surface of sorbent, various volumes of concentrated nitric acid were added into the tube to wash the La.sup.3+ to reuse La.sup.3+ (.sup.225Ac) and reduce the radiolytic damage for the sorbent. The concentration of nitric acid in the desorption process is in the range of 0.1 to 0.3 mol/L. Reference is made to FIG. 8C, which is a diagram of the adsorption percentage of Bi.sup.3+ and La.sup.3+ with respect to HDEHP-AC. Herein, the mixture of a parent radionuclide and a daughter radionuclide comprised 10 mol/L of La.sup.3+, and 10 mol/L of Bi.sup.3+. The concentration of NaNO.sub.3 for the mixture is in the range of 0.1 to 0.5 mol/L.

[0125] In combination with FIG. 6A, it may be observed that for pH>pK.sub.a (1.47), the sorption capacity for La.sup.3+ increases with increasing pH. The Bi.sup.3+ may be easily eluted using a NaI solution at pH 2, without influencing the adsorption of La.sup.3+. Indeed, there may be strong complexation of I.sup. with Bi.sup.3+, leading to desorption. There seems to be no I.sup. complexation with La.sup.3+, so that La.sup.3+ remains adsorbed on the sorbent material.

[0126] In combination with FIG. 8B, after that, a acid solution (e.g., 0.2-0.3 mol/L HNO.sub.3) would be used to elute the .sup.225Ac to reduce the radiolytic damage for the column. Then obtained .sup.225Ac can be used again after increasing the pH. The concentration of salt should not give a high influence for the sorption process according to the influence of ionic strength. Correspondingly, an alkaline solution would be added to increase the pH of the .sup.225Ac solution to improve the sorption capacity of sorbents, which can lead to increasing the ionic strength. Here the effect of NaNO.sub.3 concentration was studied to investigate the influence of ionic strength on the sorption performance of HDEHP-AC. FIG. 8C showed that the K.sub.d values for La.sup.3+ gradually decreased with increasing the concentration of NaNO.sub.3 from 0.05 to 0.5 mol/L. This was because the electrostatic attraction between La.sup.3+ and HDEHP-AC became weaker with increasing the ionic strength. Interestingly, the removal percentage for La.sup.3+ was still more than 90% in 0.5 mol/L NaNO.sub.3 solution, implying that the HDEHP-AC still had a relatively good affinity for La.sup.3+ in a relatively high ionic strength solution. As for the Bi.sup.3+, the equilibrium concentration was below the lower detection limit of ICP-MS, so the K.sub.d values for Bi.sup.3+ were still very high in the whole range, indicating that AC-P had an extreme affinity for Bi.sup.3+. This was due to the formation of inner-sphere complexes (BiOH/BiO) on HDEHP-AC.

Example 9: General Principles of the Direct Generator

[0127] Reference is made to FIG. 9, which is a schematic representation of a conceptual design of, and a process flow for, a direct .sup.225Ac/.sup.213Bi separating system, in accordance with embodiments of the present invention. Although this example is specifically for separating .sup.213Bi from .sup.225Ac, separation of other daughter radionuclides from other parent radionuclides may be performed in similar systems, in accordance with embodiments of the present invention. Arrows, indicating direction of fluid (e.g., mixture/eluent/stripping solution/ . . . ) flow, with respective numbers, refer to the following method steps, which are in accordance with embodiments of the present invention.

[0128] Step 0 (preparation phase): The sorbent materials may be conditioned with HNO.sub.3 (e.g., at a concentration of at least 0.01 M). The mixture (that is, of a parent radionuclide and a daughter radionuclide) may be prepared with HNO.sub.3 (e.g., >0.01 M) containing .sup.225Ac and .sup.213Bi.

[0129] Step 1: The mixture may be introduced into the column 10, e.g., through an inlet. Both .sup.225Ac and .sup.213Bi may be sorbed on the sorbent material of the column 10.

[0130] Step 2: An elution solution comprising NaI (e.g., at least 0.45 M) and HNO.sub.3 (e.g., 0.01 M) may be introduced into the column 10 so as to elute .sup.213Bi. That is, the selectivity of the sorbent material may be increased by the elution solution having a large ionic strength.

[0131] Step 3: To increase the lifetime of the column 10, the .sup.225Ac can be eluted by HNO.sub.3 (e.g., a solution comprising HNO.sub.3 at a concentration of from 0.1 to 0.5 M). Removing the .sup.225Ac may reduce the contact time between .sup.225Ac and the sorbent material.

[0132] Step 4: The pH of the .sup.225Ac solution obtained in step 3 is preferably at least 2. This obtained .sup.225Ac solution may be reused in step 0 of a next cycle for forming the mixture.

[0133] It is to be understood that although preferred embodiments, specific constructions and configurations, as well as materials, have been discussed herein for devices according to the present invention, various changes or modifications in form and detail may be made without departing from the scope of this invention. For example, any formulas given above are merely representative of procedures that may be used. Steps may be added or deleted to methods described within the scope of the present invention.

Example 10

[0134] By way of illustration, embodiments not being limited thereto, an example of how spherical carbon materials can be synthesized is given. In this example, the spherical sulfonated carbon material was fabricated by pyrolysing the cellulose beads at 400 C. and then via a sulfonation process. The sulfonation temperature and sulfonation time was 150 C. and 180 min, respectively.

[0135] Reference is made to FIG. 10A, which is a diagram of the synthesis process. SEM images in FIG. 10A indicated that the spherical carbonized cellulose beads were synthesized successfully. This example showed a method to synthesize the spherical carbon materials and spherical sulfonated carbon materials.

[0136] Reference is made to FIG. 10B, which is a diagram of the K.sub.d values at a range of pH values for Bi.sup.3+ and La.sup.3+, with respect to the sorbent material sulfonated carbonized cellulose beads, sulfonated at a temperature of 150 C. FIG. 10B, thereby, indicates the effect of pH on adsorption percentages of sulfonated carbonized cellulose beads towards La.sup.3+ and Bi.sup.3+. In the experiments performed for the results shown in FIG. 10B, the mixture of a parent radionuclide and a daughter radionuclide comprised 10 mol/L of La.sup.3+ and 10 mol/L of Bi.sup.3+. The amount of sorbent material was 30 mg and the amount of the mixture was 10 mL, and the contact time was 24 h at room temperature.

[0137] Further by way of illustration, the present invention not being limited thereto, an example of an experimental separation is described below. An .sup.225Ac/.sup.213Bi column was prepared with 100 mg of SCMC-500. The prepared 5 mL starting solution was composed of 200 kBq .sup.225Ac, 0.055 mol L.sup.1 HNO.sub.3 and 3.0 mol L.sup.1 NaNO.sub.3. The columns were rinsed with H.sub.2O (10 mL) and then 0.01 mol L.sup.1 HNO.sub.3 solution (2 mL). Subsequently, the prepared .sup.225Ac solution (5 mL) in a Falcon tube was passed through the column under a sorption flow rate of 1.40.1 mL min.sup.1. Thereafter, 1 mL of 0.02 mol L.sup.1 HNO.sub.3/3 mol L.sup.1 NaNO.sub.3 solution was applied to wash the Falcon tube, and then 2.5 mL of 0.02 mol L.sup.1 HNO.sub.3/3 mol L.sup.1 NaNO.sub.3 was utilized to wash the column-100. Finally, 1 mL of 1 mol L.sup.1 HCl was employed to elute the .sup.213Bi with an elution flow rate of 1.40.1 mL min.sup.1. The .sup.225Ac impurity in the elution was 0.030.01% (the activity ratio of .sup.225Ac to .sup.213Bi at the end of separation). The total separation time was 6.50.3 min. The .sup.213Bi yield was 943%.