Ionic liquid extraction system and method for extracting Mo-99

Abstract

The invention provides an ionic liquid extraction system and a method for extracting Mo-99. The ionic liquid extraction system comprises an extraction agent and a solvent, the extraction agent comprises oximido-containing ionic liquid as shown in a formula (1), and R group is imgabs0 # and R1 is selected from C4-C20 alkyl. According to the ionic liquid extraction system provided by the invention, Mo-99 can be selectively extracted, the extraction rate is high, the impurity element removal effect is good, and the extraction time is short. # imgabs1 #

Description

Technical Field

[0001] The invention relates to the field of preparation of medical radioisotopes, and in particular to an oxime-functional ionic liquid extraction system and a preparation method thereof, and a method for extracting Mo-99. Background Art

[0002] Mo-99 is the core raw material for the preparation of medical Tc-99m generators. Tc-99m drugs are widely used in nuclear medicine clinical imaging and diagnosis of various diseases.

[0003] Fission Mo-99 comes from the extraction of U-235 fission products. U-235 fission products are very complex, containing dozens of elements and more than 100 nuclides. Therefore, the extraction of fission Mo-99 is a challenging process. The process is complicated and time-consuming, and a large amount of reagents and energy are consumed during the operation. In addition, because the process is a multi-step operation, the total recovery rate of Mo-99 in the Mo-99 extraction process is low. Mo-99 is a short-half-life radioactive nuclide. During the extraction process, Mo-99 will be lost due to continuous decay. Therefore, it is necessary to develop a fast and efficient Mo-99 extraction method.

[0004] Liquid-liquid extraction is one of the most traditional and mature separation methods. It is widely used in industry due to its advantages such as large loading capacity, simple process, good separation effect, and designable extractant. However, in the process of extracting radioactive fission metals by traditional liquid-liquid extraction, there are problems such as high energy consumption, large amount of radioactive waste liquid, and irradiation decomposition of the extractant. In addition, traditional organic extraction reagents have defects such as high volatility and high toxicity. Therefore, it is necessary to develop a new extraction system. Summary of the invention

[0005] In view of this, the main purpose of the present invention is to provide a functional ionic liquid extraction system and a method for extracting Mo-99, which can improve the extraction rate, effectively remove impurities and significantly shorten the extraction process time.

[0006] To this end, the first aspect of the present invention provides an ionic liquid extraction system, comprising an extractant and a solvent, wherein the extractant comprises an oxime-containing ionic liquid as shown in formula (1):

[0007]

[0008] Among them, the R group is R1 is selected from C4-C 20 of alkyl.

[0009] In some embodiments, R1 is selected from C4-C8 alkyl.

[0010] In some embodiments, X is an anion selected from NTf2 -or PF6 - .

[0011] In some embodiments, the oxime-containing functional ionic liquid has a structure as described in formula (2) or formula (3):

[0012]

[0013] In some embodiments, the solvent includes one or more of n-octanol, ethyl acetate, chloroform, toluene, imidazole or quaternary ammonium ionic liquids;

[0014] The volume ratio of the oxime-containing ionic liquid to the solvent is 1:99 to 1:9.

[0015] The second aspect of the present application provides a method for extracting Mo-99, comprising the following steps:

[0016] The aqueous solution containing Mo-99 is extracted using the ionic liquid extraction system described in the first aspect of the present application, and the organic phase is collected after extraction.

[0017] In some embodiments, the extraction time is 5 to 30 minutes, and the extraction temperature is room temperature. Preferably, the extraction is repeated 2-3 times.

[0018] In some embodiments, the pH of the Mo-99-containing aqueous solution is 0 to 5.0; the Mo-99-containing aqueous solution includes an acid, preferably, the acid includes one or more of HNO3, HCl, and H2SO4; in the aqueous solution, the concentration of the acid is 0.00001 to 3.0 mol / L, preferably 0.001 mol / L.

[0019] In some embodiments, the method further comprises stripping the organic phase with a stripping agent; the stripping agent comprises NH4OH, (NH4)2CO3, NaHCO3, Na2CO3, preferably NH4OH or Na2CO3.

[0020] In some embodiments, in the Mo-99-containing aqueous phase, the Mo-99 exists in the form of Mo(VI).

[0021] The present invention provides an ionic liquid extraction system, which uses a functional ionic liquid containing an oxime functional group as an extractant, can specifically bind to Mo-99 in a wide pH range, and transfer Mo-99 in the fission product to the organic phase more thoroughly, so as to achieve the separation of Mo-99 from the matrix U and a large number of other fission impurities, and has high selectivity for the extraction of Mo-99. The ionic liquid extraction system of the present application has a fast reaction, can shorten the time-consuming extraction problem, and has a high Mo-99 extraction rate and a good effect on the removal of impurity elements. DETAILED DESCRIPTION

[0022] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0023] Throughout the specification, unless otherwise specifically stated, the terms used herein should be understood as meanings commonly used in the art. Therefore, unless otherwise defined, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art to which the present invention belongs. In the event of a conflict, the present specification takes precedence.

[0024] It should be noted that, in the embodiments of the present invention, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a method or device including a series of elements includes not only the elements explicitly stated, but also other elements not explicitly listed, or also includes elements inherent to the implementation of the method or device. In the absence of further restrictions, an element defined by the sentence "includes a ..." does not exclude the existence of other related elements in the method or device including the element.

[0025] It should be noted that the terms "first\second\third" involved in the embodiments of the present invention are only used to distinguish similar objects, and do not represent a specific order for the objects. It is understandable that the specific order or sequence of "first\second\third" can be interchanged where permitted. It should be understood that the objects distinguished by "first\second\third" can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein.

[0026] The oxime group in α-benzoin oxime (α-BzO) can coordinate with Mo. Two benzoin oxime molecules combine with one Mo atom to form a coordination compound, which produces a precipitate and is often used to separate Mo-99. The Cintichem process developed by an American company uses the α-benzoin oxime precipitation method to separate Mo-99, but this process involves the precipitation of radioactive substances in a hot chamber and the redissolution of the precipitate, which is inconvenient to operate in a hot chamber.

[0027] Ionic liquids are green solvents with low toxicity, low vapor pressure, stable chemical properties, good thermal stability, and good solubility. In recent years, ionic liquids have been widely used in the extraction of metal ions, especially radioactive metal ions. Compared with traditional extraction systems, ionic liquids have the advantages of high extraction efficiency, good selectivity, high stability, low volatility, and environmental friendliness.

[0028] Considering the high stability and high safety of ionic liquids, and the characteristics that oxime groups can specifically bind to Mo, the present invention provides an ionic liquid extraction system, comprising an extractant and a solvent, wherein the extractant comprises an oxime-containing ionic liquid as shown in formula (1):

[0029]

[0030] Among them, the R group is R1 is selected from C4-C 20 of alkyl.

[0031] In the present application, the functional ionic liquid having a structure as shown in formula (1) has an oxime functional group, which can coordinate with Mo-99, selectively and quickly transfer Mo-99 from the aqueous phase to the organic phase, and achieve specific extraction of Mo-99. Among them, the R group is a substituted imidazole group, which is an aromatic ring that satisfies the 4n+2 rule and exhibits better stability under the same dose of irradiation conditions. At the same time, one of the N atoms of the imidazole group has a lone pair of electrons, which can coordinate with Mo(VI), thereby facilitating the improvement of the extraction rate of Mo-99.

[0032] In the present application, R1 is C4-C 20 By making the number of carbon atoms of the alkyl group of the ionic liquid within the above range, the solubility of the ionic liquid in organic solvents such as n-octanol and toluene is relatively large, which is beneficial for the extraction of Mo-99 by the ionic liquid. In some embodiments, R1 is a C4-C8 alkyl group, which is beneficial to further improve the extraction rate of the ionic liquid extraction system.

[0033] In this application, the term "alkyl" refers to a group having the general formula C n H 2n+1 A group formed by a branched or straight chain saturated alkyl group losing a hydrogen atom. 20The term "alkyl" refers to an alkyl group having 4 to 20 carbon atoms. Examples of C4-C20 alkyl groups include, but are not limited to, n-butyl, isobutyl, tert-butyl, n-pentyl, 1-methylbutyl, 2-methylbutyl, 3-methylbutyl, 1-ethylpropyl, 2,2-dimethylpropyl, 1,1-dimethylpropyl, tert-pentyl, n-hexyl, 1-methylpentyl, 2-methylpentyl, 3-methylpentyl, 1,2-dimethylbutyl, 2,3-dimethylbutyl, 2,2-dimethylbutyl, 3-ethylbutyl, n-heptyl, 2-methyl hexyl, n-octyl, 2-methylheptyl, 3-methylheptyl, 2,2-dimethylhexyl, 2,3-dimethylhexyl, 2,4-dimethylhexyl, 3,3-dimethylhexane, 2,2,3-trimethylpentyl, 2,3,3-trimethylpentyl, 2-methyl-3-ethylpentyl, 3-methyl-3-ethylpentyl, 2,2,3,3-tetramethylbutyl, nonyl, decyl, undecyl, dodecyl, etc. are linear or branched alkyl groups having 4 to 20 carbon atoms. In some optional embodiments, R1 is selected from C4-C 10 Preferably, the alkyl group is C4-C8.

[0034] In some embodiments, X is an anion selected from the group consisting of bis(trifluoromethanesulfonyl)imide ion (NTf2 - ), hexafluorophosphate ion (PF6 - ). NTf2 - and PF6 - The larger the volume, the larger the distance between the positive and negative charges of the anions and cations in the ionic liquid, making the ionic liquid exhibit a lower viscosity at room temperature, which is beneficial to extraction and mass transfer. On the other hand, the larger anions can change the polarity of the ionic liquid, increasing the solubility of the ionic liquid in non-water-soluble solvents with lower polarity, which is beneficial to further improve the extraction rate of Mo-99 by the ionic liquid.

[0035] In some embodiments, the oxime-containing functional ionic liquid has a structure as described in formula (2) or formula (3):

[0036]

[0037] The oxime-containing functional ionic liquid having the structure shown in formula (2) is beneficial for the specific extraction of Mo-99. The oxime-containing functional ionic liquid having the structure shown in formula (3) is beneficial for more efficient extraction of Mo-99 and has a higher extraction rate.

[0038] In some embodiments, the solvent includes one or more of ethyl acetate, toluene, chloroform, n-octanol, imidazole or quaternary ammonium ionic liquids. Using the above substances as solvents is conducive to adjusting the viscosity of the oxime-containing ionic liquid, thereby facilitating the full mixing of the organic phase and the aqueous phase to achieve rapid extraction of Mo-99. In some preferred embodiments, the solvent includes n-octanol.

[0039] In some embodiments, the volume ratio of the oxime-containing functional ionic liquid to the solvent is 1:99 to 1:9. By making the volume ratio of the functional ionic liquid to the solvent within the above range, it is beneficial to the rapid extraction of Mo-99 and the efficient use of the functional ionic liquid.

[0040] Preparation method of functional ionic liquid containing oxime group

[0041] In the present application, the oxime-containing functional ionic liquid can be prepared by the following steps:

[0042]

[0043] Step (1): chloromethylating salicylaldehyde to generate intermediate a;

[0044] Step (2): reacting the intermediate product a with a substituted imidazole to generate an organic ion salt b;

[0045] Step (3): reacting the organic ion salt b with hydroxylamine hydrochloride to obtain an intermediate product c; and

[0046] Step (4): subjecting the intermediate product c to anion exchange reaction to obtain the oxime-containing functional ionic liquid.

[0047] In some embodiments, the chloromethylation reaction is carried out using formaldehyde (or paraformaldehyde) and concentrated hydrochloric acid. In some embodiments, the concentration of concentrated hydrochloric acid is 36%-38%. In some embodiments, the reaction conditions of the chloromethylation reaction are room temperature reaction for 24 hours under the catalysis of Lewis acid (such as zinc chloride).

[0048] In some embodiments, in step (2), the structural formula of the substituted imidazole is Wherein R1 is selected from C4-C 20 An alkyl group, preferably a C4-C8 alkyl group. 20 The alkyl group has the same meaning as defined above.

[0049] In some embodiments, in step (2), the reaction conditions for generating the organic ion salt are to dropwise add the imidazole structure reactant into the toluene solvent and react at 60-70° C. for 6 hours.

[0050] In some embodiments, in step (3), the reaction with hydroxylamine hydrochloride is carried out in an alkaline environment. In some embodiments, in step (3), the organic salt ion b reacts with hydroxylamine hydrochloride and NaOH, using ethanol and water as solvents, and reacts at room temperature for at least 1 hour.

[0051] In some embodiments, in step (4), a salt containing a target anion is used to carry out anion exchange reaction with the intermediate product C. In some embodiments, the target anion is selected from an acid anion, NTf2 - 、Hexafluorophosphate ion (PF6 - ).

[0052] Method for extracting Mo-99

[0053] The second aspect of the present application also provides a method for extracting Mo-99, comprising the following steps: extracting the organic phase including the ionic liquid extraction system described in the first aspect of the present application with the aqueous solution containing Mo-99, and collecting the organic phase after extraction. The functional ionic liquid containing oxime groups in the ionic liquid extraction system of the present application specifically binds to Mo-99, and can extract Mo-99 in the aqueous phase into the organic phase. The extraction process is fast, and one extraction can be completed within 5-15 minutes, thereby saving time; the method of the present application has a high extraction rate, and the extraction rate of one extraction can reach 99.4%; in addition, the method of the present application has a good removal effect on impurity elements such as U, Sr, Cs, Te, I, Zr, Ru, etc., and can achieve high selectivity for Mo-99.

[0054] In the present application, the aqueous solution containing Mo-99 can be a target solution containing a U matrix and fission impurities Sr, Cs, Te, I, Zr, Ru, etc. obtained by dissolving a low-enriched uranium or high-enriched uranium target in a concentrated nitric acid solution after irradiating the target in a reactor, or it can be a target solution obtained by dissolving a natural Mo target or an enriched Mo-98 target in a reactor with a nitric acid solution.

[0055] In some embodiments, the extraction time of the extraction is 15 to 30 minutes. The ionic liquid extraction system of the present application reacts quickly with Mo-99 and the extraction time is short. Thus, the time consumption of the Mo-99 extraction and separation process can be reduced, and the loss of Mo-99 caused by the continuous decay can be reduced.

[0056] In some embodiments, the extraction temperature is room temperature. The method of the present application is operated at a lower temperature without heating conditions, and the extraction operation is more convenient.

[0057] In some embodiments, the extraction is repeated 2-3 times. By repeating the extraction steps, the extraction rate of the ionic liquid extraction system can be increased, and the extraction rate can reach 99.9%.

[0058] In some embodiments, the pH of the aqueous phase containing Mo-99 is 0 to 5.0. The ionic liquid extraction system of the present application can extract Mo-99 in a wide pH range. Exemplarily, the pH of the aqueous phase containing Mo-99 can be 0, 1.0, 2.0, 3.0, 4.0, 5.0. In some preferred embodiments, the pH of the aqueous phase containing Mo-99 is 2.0-4.0. By making the pH of the aqueous phase within the above range, it is beneficial to extract Mo-99 more efficiently.

[0059] In some embodiments, the aqueous phase containing Mo-99 includes an acid. By making the aqueous phase containing Mo-99 include an acid, the oxime-containing ionic liquid can specifically bind to Mo-99 in the aqueous phase, thereby enabling specific extraction of Mo-99. In some embodiments, the acid includes one or more of HNO3, HCl, and H2SO4. In some preferred embodiments, the acid is consistent with the medium used to dissolve the U target or Mo target of Mo-99, and no medium conversion is required during extraction and separation, simplifying the operation. Using the above-mentioned acid, in some embodiments, the concentration of the acid in the aqueous phase is 0.00001 to 3.0 mol / L. By making the concentration of the acid within the above range, it is ensured that Mo-99 exists in the chemical form of molybdate, so that the oxime-containing ionic liquid can specifically bind to Mo, thereby achieving efficient extraction of Mo-99.

[0060] In some embodiments, in the aqueous phase containing Mo-99, Mo-99 exists in the form of Mo(VI). Mo-99 in the form of Mo(VI) has a stronger coordination effect with the oxime-containing ionic liquid, which is beneficial to the specific extraction of Mo-99 by the ionic liquid.

[0061] The technical solution of the present application will be described in detail below in conjunction with specific embodiments.

[0062] Example

[0063] Example 1

[0064] ({4-hydroxy-3-[-(hydroxyaminoylidene)methyl]phenyl}methyl-3-octylimidazolium bis(trifluoromethanesulfonyl imide) Synthesis of ([OHIB][NTf2])

[0065] According to the reaction path shown below, ({4-hydroxy-3-[-(hydroxyamino)methyl]phenyl}methyl-3-octylimidazole bis(trifluoromethanesulfonyl)imide salt ([OHIB][NTf2])) was synthesized:

[0066]

[0067] Synthesis of 2-hydroxy-5-chloromethylbenzaldehyde (intermediate product a): Add 6.00g (0.20mol) of paraformaldehyde, 0.100g of ZnCl2 (catalyst) and 60.0mL of concentrated hydrochloric acid to a round-bottom flask, stir thoroughly, and after the paraformaldehyde is dissolved, add 20.9mL (0.21mol) of salicylaldehyde to the flask, and react at room temperature for 24h. After filtering, wash with saturated sodium bicarbonate solution until no bubbles are generated, and collect the solid. Recrystallize with hot n-hexane, filter, wash with n-hexane and dry to obtain a white solid.

[0068] Synthesis of 1-octyl-3-(3-formyl-4-hydroxybenzyl)imidazolium chloride (intermediate product b): At room temperature, 25.5 g (0.15 mol) of 2-hydroxy-5-chloromethylbenzaldehyde was added to a round-bottom flask, and 60.0 mL of toluene was added and heated to dissolve. Then, 33.1 mL (0.16 mol) of N-octylimidazole was slowly added, and refluxed at 60°C for 6 h. After the reaction stopped, the mixture was cooled, filtered, and the solid was washed with toluene 4 times. The solid was collected and dried in a vacuum drying oven to obtain 45.6 g of light yellow granular solid. The yield of this process was 86.88%.

[0069] Synthesis of ({4-hydroxy-3-[-(hydroxylamine ylidene) methyl] phenyl} methyl-3-octylimidazole bis(trifluoromethanesulfonyl)imide salt (containing oxime functional ionic liquid): At room temperature, 4.40 g (0.11 mol) of NaOH and 7.70 g (0.11 mol) of hydroxylamine hydrochloride were added to a round-bottom flask, and 30.0 mL of deionized water was added to dissolve, 35.0 g (0.10 mol) of 1-octyl-3-(3-formyl-4-hydroxybenzyl) imidazole chloride (intermediate product b) was weighed, 30.0 mL of water and 60.0 mL of anhydrous ethanol were added to dissolve, and the above two solutions were mixed and reacted at room temperature for 4 h; at the same time, 31.6 g (0.11 mol) of bis(trifluoromethane) was weighed. Lithium sulfonyl imide (LiTFSI) was added to 30 mL of water and dissolved for later use. After the above reaction was completed, the dissolved lithium bis(trifluoromethanesulfonyl)imide solution was added and reacted at room temperature for 1 hour. After the reaction stopped, the organic phase was separated and repeatedly washed with deionized water until no precipitation was produced after the washed water was added to the AgNO3 solution. The organic phase was collected, acetone was added to dissolve, and the solvent was removed by rotary evaporation. This was repeated 2-3 times to obtain 54.6 g of a yellow-brown viscous oily liquid, i.e., the target product ({4-hydroxy-3-[-(hydroxylamine subunit) methyl] phenyl} methyl-3-octylimidazole bis(trifluoromethanesulfonyl)imide salt ([OHIB][NTf2]). The yield of this process was 89.56%.

[0070] Construction of ionic liquid extraction system

[0071] 4.62 mL of the functional ionic liquid ([OHIB][NTf2]) prepared above was added to the extraction tube, and then 95.38 mL of n-octanol was added to make the concentration of the oxime-containing functional ionic liquid 0.1 mol / L, and the mixture was thoroughly mixed to construct a functional ionic liquid extraction system (organic phase).

[0072] Verification of the extraction effect of ionic liquid extraction system

[0073] Based on the theoretical yield calculation results, according to the content ratio of the produced Mo (including Mo-99 and stable Mo) and other fission elements Sr, Te, Ru, I, Zr, Cs, etc., a 1mol / L HNO3 solution was used as the dissolution medium to prepare a simulated solution. The concentrations of various ions in the simulated solution were: 120mg / L Mo(VI), 75mg / L Sr(II), 277mg / L Zr(IV), 90mg / L Ru(III), 34mg / L Te(II), 75mg / L Cs, 28mg / L Zr(IV), etc. - (The simulated liquid includes Mo-99 and I-125 as tracers.) The pH of the simulated solution is 3.

[0074] At room temperature, 3 mL of the ionic liquid extraction system constructed above was taken and 3 mL of the simulated solution was fully mixed and extracted in an extraction tube for 5 min. After phase separation, the lower organic phase was collected, and the aqueous phase was extracted three times. The Mo-99 and I-125 counts in the simulated liquid and the aqueous phase after extraction were measured with a γ counter. The contents of impurity elements Sr, Te, Ru, Zr and Cs in the aqueous phase were determined by ICP-MS. The extraction rate of Mo-99 was calculated from this, and the Mo-99 extraction rate = (total radioactive counts of Mo-99 in the simulated solution - radioactive counts of Mo-99 in the aqueous phase) / total radioactive counts of Mo-99 in the simulated solution × 100%. Impurity removal rate = (initial element content in the simulated solution - residual element content in the aqueous phase) / initial element content in the simulated solution × 100%. The experimental results of the Mo-99 extraction rate and impurity element removal rate obtained by testing and calculating are shown in Table 1.

[0075] Table 1 Experimental results of ionic liquid extraction of Mo-99 in Example 1 (%)

[0076]

[0077] It can be seen from the above results that after one extraction, the ionic liquid extraction system of the present application has an extraction rate of 99.4% for Mo-99 in the aqueous phase, and after two extractions, the extraction rate of Mo-99 is 99.9%. After three extractions, Mo-99 in the aqueous phase can be basically completely extracted into the organic phase. Under the conditions of ionic liquid concentration of 0.1 mol / L and pH = 3, after one extraction, Sr and Cs can be completely removed, and 93.7%, 97.2%, 95.3%, and 89.3% of Te(Ⅳ), I - , Zr(Ⅳ), and Ru(Ⅲ), showing very good decontamination effect on fission impurities.

[0078] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification under the inventive concept of the present invention, or direct / indirect application in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. An ionic liquid extraction system, comprising an extractant and a solvent, characterized in that: The extractant comprises an oxime-containing ionic liquid as shown in formula (1): Among them, the R group is R1 is selected from C4-C 20 of alkyl.

2. The ionic liquid extraction system according to claim 1, wherein: R1 is selected from C4-C8 alkyl groups.

3. The ionic liquid extraction system according to claim 1 or 2, wherein: X is an anion selected from NTf2 - or PF6 - .

4. The ionic liquid extraction system according to claim 1 or 2, wherein: The oxime-containing functional ionic liquid has a structure as described in formula (2) or formula (3):

5. The ionic liquid extraction system according to claim 1 or 2, wherein: The solvent includes one or more of n-octanol, ethyl acetate, chloroform, toluene, imidazole or quaternary ammonium ionic liquids; The volume ratio of the oxime-containing ionic liquid to the solvent is 1:99 to 1:

9.

6. A method for extracting Mo-99, comprising the following steps: The aqueous solution containing Mo-99 is extracted using the ionic liquid extraction system described in any one of claims 1 to 6, and the organic phase is collected after the extraction.

7. The method according to claim 6, wherein: The extraction time is 5 to 30 minutes, and the extraction temperature is room temperature. Preferably, the extraction is repeated 2 to 3 times.

8. The method according to claim 6 or 7, wherein: The pH of the Mo-99-containing aqueous solution is 0-5.0; the Mo-99-containing aqueous solution includes an acid, preferably, the acid includes one or more of HNO3, HCl, H2SO4; in the aqueous solution, the concentration of the acid is 0.00001-3.0 mol / L, preferably 0.001 mol / L.

9. The method according to claim 6 or 7, wherein: The method further comprises stripping the organic phase with a stripping agent; the stripping agent comprises NH4OH, (NH4)2CO3, NaHCO3, Na2CO3, preferably NH4OH or Na2CO3.

10. The method according to claim 7, wherein: In the Mo-99-containing aqueous phase, Mo-99 exists in the form of Mo(VI).

Images