Method for directly extracting neptunium based on conjugate cavity structure

Abstract

The invention provides a method for directly extracting neptunium based on a conjugate cavity structure. The conjugated cavity type molecule can be used for directly and efficiently extracting neptunium (Np). On one hand, the molecule has a cavity structure highly matched with metal ions, and on the other hand, the structure has high conjugacy and can be effectively combined with actinide elements with obvious electron delocalization. Based on the characteristics, direct and efficient extraction of Np is realized under the condition of not depending on an oxidation-reduction process. The method has a good application prospect in the field of advanced nuclear fuel circulation.

Description

Technical Field

[0001] The invention belongs to the technical field of nuclear fuel circulation and waste liquid treatment, and in particular relates to a method for directly extracting neptunium based on a conjugated cavity structure. Background Art

[0002] Neptunium (Np) is an important transuranic element, mainly produced through the process of nuclear energy utilization. Because its main isotope Np-237 has a very long half-life (2.144×10 6 Years), so it may cause persistent environmental radiation hazards and threats to human health. On the other hand, Np-237 can be used to prepare Pu-238, a space heat source material, and is regarded as a valuable nuclear resource. Therefore, the extraction and recovery of Np from spent fuel can not only reduce the long-term hazards of radioactive waste, but also has important significance for the effective utilization of nuclear resources. Np in spent fuel usually exists in the form of pentavalent Np(V), and conventional extractants have weak extraction ability for Np(V). In order to improve the recovery efficiency of Np, it is usually necessary to oxidize or reduce the difficult-to-extract Np(V) to easily extractable Np(VI) or Np(IV). Nevertheless, the redox process of Np between different valence states is greatly affected by the system. In addition, the additionally introduced redox reagents may cause adverse interference to the separation and recovery of other coexisting metal ions in spent fuel, affecting the stable operation of subsequent processes. Therefore, developing a system that does not rely on the regulation of Np valence state and directly extracts Np(V) has become an important strategy to break through the bottleneck problem of efficient recovery of Np. Summary of the invention

[0003] One of the purposes of the present invention is to provide a functional group-modified condensed ring / aromatic ring molecule containing heteropolycoordinate atoms.

[0004] The functional group-modified fused ring / aromatic ring molecules containing heteropolycoordinate atoms provided by the present invention have the following parent structure:

[0005]

[0006] Wherein, A, B, C, and D represent coordinating atoms, and are independently selected from at least one of N, O, S, and P.

[0007] The above functional group-modified fused ring / aromatic ring molecules containing heteropolycoordinating atoms include compounds represented by formula I, formula II, and formula III:

[0008]

[0009] In Formula I, Formula II, and Formula III, A, B, C, and D represent coordinating atoms, each independently selected from at least one of N, O, S, and P;

[0010] In Formula I, R1 and R2 are the same or different and are independently selected from C1-C 10 A straight or branched alkyl group, a substituted or unsubstituted aryl group, or R1, R2 and the N connected thereto form a saturated or unsaturated five-membered or six-membered ring, wherein the H on the carbon atom of the saturated or unsaturated five-membered or six-membered ring can be substituted by a straight or branched alkyl group of C1-C6;

[0011] The aromatic group includes benzene ring, furyl, imidazolyl, etc.;

[0012] The substituent in the substituted aryl group may be at least one of a halogen, a C1-C6 straight or branched alkyl group, and a nitro group;

[0013] R3 and R4 are the same or different and are independently selected from C1-C 10 A straight or branched alkyl group, a substituted or unsubstituted aryl group, or R1, R2 and the N connected thereto form a saturated or unsaturated five-membered or six-membered ring, wherein the H on the carbon atom of the saturated or unsaturated five-membered or six-membered ring can be substituted by a straight or branched alkyl group of C1-C6;

[0014] The aromatic group includes benzene ring, furyl, imidazolyl, etc.;

[0015] The substituent in the substituted aryl group may be at least one of a halogen, a C1-C6 straight or branched alkyl group, and a nitro group;

[0016] In Formula II, R1, R2, R3, and R4 are each independently selected from C1-C 10 At least one of a linear or branched alkyl group, a substituted or unsubstituted aryl group, a saturated or unsaturated five-membered or six-membered ring containing or not containing heteroatoms, R1, R2 (R3, R4) and the carbon atom to which they are attached to form a saturated or unsaturated five-membered or six-membered ring fused to a heteroaromatic ring, wherein the H on the carbon atom of the saturated or unsaturated five-membered or six-membered ring may be substituted by a C1-C6 linear or branched alkyl group;

[0017] The aromatic group includes benzene ring, furyl, imidazolyl, etc.;

[0018] The substituent in the substituted aryl group may be at least one of halogen, C1-C6 straight or branched alkyl, C1-C6 alkoxy, and nitro;

[0019] The aromatic ring containing C and D atoms in formula II may contain at least one N atom in addition to the C or D coordinating atoms;

[0020] In formula III, R1 and R2 are the same as those defined in formula I, and R3 and R4 are the same as those defined in formula II. The aromatic ring containing D atoms may contain at least one N atom in addition to the D coordinating atom.

[0021] The above functional group-modified condensed ring / aromatic ring molecule containing heteropolycoordinating atoms may specifically be any one of the following compounds:

[0022]

[0023] The use of the above functional group-modified condensed ring / aromatic ring molecules containing heteropoly-coordinated atoms as extraction agents for actinide elements also falls within the protection scope of the present invention.

[0024] The actinide element may specifically be Np(V).

[0025] The functional group-modified condensed ring / aromatic ring molecules containing heteropoly-coordinated atoms are used as actinide extraction reagents in the fields of radioactive waste liquid separation and nuclear fuel cycle.

[0026] Generally speaking, when the coordination site of the extraction reagent is highly compatible with the size of the target ion, it is conducive to the effective extraction of the metal. In addition, the deepening of the conjugation degree of the ligand molecule can promote its binding with the actinide elements with stronger electron delocalization. After systematic research, it was found that the functional group-modified condensed ring / aromatic ring molecules containing heteropoly coordinated atoms of the present invention have the above properties at the same time. On the one hand, the modified condensed ring / aromatic ring molecules have a cavity that is highly compatible with the metal ion ( Figure 1 a), on the other hand, the fused ring / aromatic ring structure itself has a high degree of conjugation ( Figure 1 b). Therefore, this type of ligand has the potential to achieve direct and efficient extraction of actinides such as Np(V).

[0027] The second object of the present invention is to provide a method for directly extracting Np(V) using the above-mentioned functional group-modified fused ring / aromatic ring molecules containing heteropoly coordinated atoms.

[0028] The method for directly extracting Np(V) provided by the present invention comprises the following steps:

[0029] The functional group-modified condensed ring / aromatic ring molecules containing heteropolycoordinate atoms are dissolved in an organic solvent to obtain an organic phase; the organic phase is directly mixed with an acidic aqueous solution containing Np(V), and after the two phases are balanced, the phases are separated by centrifugation to achieve the extraction of neptunium.

[0030] In the above method, the organic solvent includes any one or a mixture of cycloalkanes, fatty alcohols, ketones, and aromatic compounds, and specifically can be any one or a mixture of n-octanol, dodecane, benzene, toluene, cyclohexane, cyclohexanone, and m-nitrotrifluorotoluene; wherein the ratio of the mixture of the organic solvents is not specifically limited, and generally any ratio is acceptable;

[0031] The concentration range of the functional group-modified condensed ring / aromatic ring molecules containing heteropolycoordinate atoms in the organic phase can be 10 -4-1mol / L;

[0032] The acidic aqueous solution includes a perchloric acid aqueous solution, a nitric acid aqueous solution, a sulfuric acid aqueous solution, a hydrochloric acid aqueous solution, a phosphoric acid aqueous solution, and the like.

[0033] The acidity range of the aqueous solution may be 10 -5 -14mol / L.

[0034] The concentration range of Np ions in the aqueous solution can be 10 -8 -10 -3 mol / L;

[0035] The phase ratio (volume ratio) of the above two phases can be any ratio within the range of 1:10-10:1;

[0036] The two-phase mixing time can be 1-360min;

[0037] The centrifugal conditions are: 3000-5000 rpm, 1-5 min.

[0038] Compared with the prior art, the present invention has the following advantages and outstanding technical effects:

[0039] 1) The extraction system provided by the present invention can fundamentally get rid of the dependence on the regulation of the valence state of Np and directly and efficiently extract Np(V) without introducing additional redox reagents.

[0040] 2) The extraction system provided by the present invention can cover a wide range of acidity, which greatly enhances the applicability of the method in the field of radioactive waste liquid separation and shows good application prospects in the field of advanced nuclear fuel cycle.

[0041] 3) The equipment, materials and reagents involved in the present invention can all be obtained through commercial channels, without the need for targeted customization, design and preparation, thereby fundamentally achieving cost reduction and efficiency improvement. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This indicates that the functional group-modified condensed ring / aromatic ring molecules containing heteropolycoordinate atoms of the present invention have both (a) cavity matching and (b) a large conjugated system. DETAILED DESCRIPTION

[0043] The present invention is further described in detail below in conjunction with specific embodiments, and the examples provided are only for illustrating the present invention, rather than for limiting the scope of the present invention. The examples provided below can be used as a guide for further improvements by those of ordinary skill in the art, and do not constitute a limitation of the present invention in any way.

[0044] The experimental methods in the following examples, unless otherwise specified, are conventional methods and are performed according to the techniques or conditions described in the literature in the art or according to the product instructions.

[0045] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.

[0046] In the following examples, the metal ion Np is concentrated in the organic phase at a concentration (C Np-org. ) and the concentration in the aqueous phase (C Np-aq. ) is defined as the distribution ratio (Distribution ratio ofNp), abbreviated as D Np .

[0047] The ligands used in the following examples and comparative examples were prepared according to the corresponding literature:

[0048] L7: Xiao, CL; Wang, CZ; Yuan, LH; Li, B.; He, H.; Wang, SA; Zhao, YL; Chai, ZF; Shi, WQExcellent selectivity for actinides with a tetradentate2,9-diamide-1,10-phenanthroline ligand in highly acidic solution: a hard-softdonor combined strategy.Inorganic Chemistry.2014,53,1712-1720.

[0049] L8: Lewis, FW; Harwood, LM; Hudson, MJ; Drew, MGB; Desreux, JF; Vidick, G.; Bouslimani, N.; Modolo, G.; Wilden, A.; Sypula, M.; Vu, TH; Simonin, JP. Highly efficient separation of actinides from lanthanides by aphenanthroline-derived bis-triazine ligand. Journal of the American Chemical Society. 2011, 133, 13093-13102.

[0050] L9: Yang, XF; Fang, D.; Chen, LJ; Liu, YY; Wang, SH; Xu, L.; Zhang, AY; Su, J.; Au.2024,doi.org / 10.1021 / jacsau.4c00684.

[0051] L10: Foreman, MRS; Hudson, MJ; Drew, MGB; Hill, C.; Madic, C. Complexesformed between the quadridentate, heterocyclic molecules6,6′-bis-(5,6-dialkyl-1,2,4-triazin-3-yl)-2,2′-bipyridine(BTBP)and lanthanides(III):implications for the partitioning ofactinides(III)and lanthanides(III).DaltonTransactions.2006,13,1645-1653.

[0052] L11: Trumm, S.; Geist, A.; Panak, PJ; T.An improved hydrolytically-stable bis-triazinyl-pyridine(BTP) for selective actinideextraction.Solvent Extraction andIon Exchange.2011,29,213-229.

[0053] Example 1

[0054] The ligand L7 was dissolved in m-nitrotrifluorotoluene to prepare an organic solution with a concentration of 0.1 mol / L as the organic phase. -6mol / LNp(V) was added to 14mol / L sulfuric acid solution as the aqueous phase. The organic phase and aqueous phase were mixed at a ratio of 1:1 for 1 min. After the two phases were balanced, they were centrifuged (3000 rpm, 5 min) to collect the organic phase and aqueous phase respectively. The extraction distribution ratio of Np was measured to be 273.

[0055] Example 2

[0056] Ligand L8 was dissolved in n-octanol to a concentration of 10 -4 mol / L organic solution as the organic phase. - 8 mol / LNp(V) was added to 1mol / L nitric acid solution as the aqueous phase. The organic phase and the aqueous phase were mixed at a ratio of 10:1 for 60 minutes. After the two phases were balanced, they were centrifuged (4000 rpm, 3 minutes) to collect the organic phase and the aqueous phase respectively. The extraction distribution ratio of Np was measured to be 198.

[0057] Example 3

[0058] The ligand L9 was dissolved in cyclohexanone to prepare an organic solution with a concentration of 1 mol / L as the organic phase. - 3 mol / LNp(V) added to 10 -5 mol / L hydrochloric acid solution as the aqueous phase. The organic phase and the aqueous phase were mixed at a ratio of 1:10 for 360 min. After the two phases were balanced, they were centrifuged (5000 rpm, 1 min) to collect the organic phase and the aqueous phase respectively. The extraction distribution ratio of Np was measured to be 221.

[0059] Comparative Example 1

[0060] Ligand L10 was dissolved in n-octanol to a concentration of 10 -4 mol / L organic solution as the organic phase. -8 mol / LNp(V) was added to 1mol / L nitric acid solution as the aqueous phase. The organic phase and aqueous phase were mixed at a ratio of 10:1 for 60 min, centrifuged (4000 rpm, 3 min), and the organic phase and aqueous phase were collected separately. The extraction distribution ratio of Np was measured to be 0.04.

[0061] Comparative Example 2

[0062] Ligand L11 was dissolved in n-octanol to a concentration of 10 -4 mol / L organic solution as the organic phase. -8mol / L Np(V) was added to 1 mol / L nitric acid solution as the aqueous phase. The organic phase and aqueous phase were mixed at a ratio of 10:1 for 60 min, centrifuged (4000 rpm, 3 min), and the organic phase and aqueous phase were collected separately. The extraction distribution ratio of Np was measured to be 0.007.

[0063]

[0064] It can be seen from the above embodiments and comparative examples that when the extraction reagent molecule does not have a large conjugated system (Example 2; Comparative Example 1) or an adapted coordination cavity (Example 2; Comparative Example 2), direct and efficient extraction of Np(V) cannot be achieved.

[0065] Table 1 shows the extraction distribution ratio of conventional extractants to Np(V)

[0066] Table 1. Extraction distribution ratio of conventional extractants for Np(V)

[0067]

[0068]

[0069] References:

[0070] DHHA,DHOA,DEHBA,DEHiBA:Gogolski,JM;Zalupski,PR;Grimes,TS;Jensen,MPNeptunium extraction by N,N-dialkylamides.RadiochimicaActa.2020,108,707-716.

[0071] DOODA, TODGA, MIDOA, NTAamide, MDOA: Sasaki, Y.; Tsubata, Y.; Kitatsuji, Y.; Sugo, Y.; Shirasu, N.; Morita, Y.; Kimura, T. Extraction behavior of metal ions by TODGA, DOODA, MIDOA, and NTAamide extractants from HNO3 to n-dodecane. SolventExtraction andIon Exchange.2013,31,401-415.

[0072] DMDHOPDA: Sasaki, Y.; Choppin, GRExtraction of Np(V) by N,N'-dimethyl-N,N'-dihexyl-3-oxapentanediamide. Radiochimica. Acta. 1998, 80, 85-88.

[0073] TRPO: Wang, JC; Song, CL

[0074] CMPO:Wisnubroto,DS;Nagasaki,S.;Enokida,Y.;Suzuki,A.Effect ofTBP onsolvent extraction ofNp(V)with m-octyl(phenyl)-,NN diisobutylcarbamoylmethylphosphine oxide.Journal of Nuclear Science and Technology.1992,29,263-268.

[0075] HDEHP: Svantesson, I.; Persson, G.; I.;Liljenzin,JO,Distribution ratios and empirical equations for the extraction of elements inPUREX high level waste solution—II:HDEHP.Journal ofInorganic andNuclearChemistry.1980,42,1037-1043.

[0076] Compared with conventional extractants, the use of the molecule with a large conjugated system and a suitable coordination cavity as an extractant can achieve direct and efficient extraction of Np(V).

[0077] The present invention has been described in detail above. For those skilled in the art, without departing from the purpose and scope of the present invention, and without the need to carry out unnecessary experimental conditions, the present invention can be implemented in a wide range under equivalent parameters, concentrations and conditions. Although the present invention provides specific embodiments, it should be understood that the present invention can be further improved. In a word, according to the principles of the present invention, the application is intended to include any changes, uses or improvements to the present invention, including departure from the disclosed scope in the application, and changes made with conventional techniques known in the art.

Claims

1. A functional group-modified fused ring / aromatic ring molecule containing heteropolycoordinate atoms, having the following parent structure: in, A, B, C, and D represent coordinating atoms, and are each independently selected from at least one of N, O, S, and P.

2. The functional group-modified fused ring / aromatic ring molecule containing heteropolycoordinate atoms according to claim 1, characterized in that: The fused ring / aromatic ring molecules include compounds represented by Formula I, Formula II, and Formula III: In Formula I, Formula II, and Formula III, A, B, C, and D represent coordinating atoms, each independently selected from at least one of N, O, S, and P; In Formula I, R1 and R2 are the same or different and are independently selected from C1-C 10 A straight or branched alkyl group, a substituted or unsubstituted aryl group, or R1, R2 and the N connected thereto form a saturated or unsaturated five-membered or six-membered ring, wherein the H on the carbon atom of the saturated or unsaturated five-membered or six-membered ring can be substituted by a straight or branched alkyl group of C1-C6; The aromatic group includes a benzene ring, a furyl group, and an imidazolyl group; The substituent in the substituted aryl group may be at least one of halogen, C1-C6 straight or branched alkyl, and nitro; R3 and R4 are the same or different and are independently selected from C1-C 10 A straight or branched alkyl group, a substituted or unsubstituted aryl group, or R1, R2 and the N connected thereto form a saturated or unsaturated five-membered or six-membered ring, wherein the H on the carbon atom of the saturated or unsaturated five-membered or six-membered ring can be substituted by a straight or branched alkyl group of C1-C6; The aromatic group includes a benzene ring, a furyl group, and an imidazolyl group; The substituent in the substituted aryl group may be at least one of halogen, C1-C6 straight or branched alkyl, and nitro; In Formula II, R1, R2, R3, and R4 are each independently selected from C1-C 10 At least one of a linear or branched alkyl group, a substituted or unsubstituted aryl group, a saturated or unsaturated five-membered or six-membered ring containing or not containing heteroatoms, R1, R2 (R3, R4) and the carbon atom to which they are attached to form a saturated or unsaturated five-membered or six-membered ring fused to a heteroaromatic ring, wherein the H on the carbon atom of the saturated or unsaturated five-membered or six-membered ring may be substituted by a C1-C6 linear or branched alkyl group; The aromatic group includes a benzene ring, a furyl group, and an imidazolyl group; The substituent in the substituted aryl group may be at least one of halogen, C1-C6 straight or branched alkyl, C1-C6 alkoxy, and nitro; The aromatic ring containing C and D atoms in formula II may contain at least one N atom in addition to the C or D coordinating atoms; In formula III, R1 and R2 are the same as those defined in formula I, and R3 and R4 are the same as those defined in formula II. The aromatic ring containing D atoms may contain at least one N atom in addition to the D coordinating atom.

3. The functional group-modified fused ring / aromatic ring molecule containing heteropolycoordinate atoms according to claim 1 or 2, characterized in that: The condensed ring / aromatic ring molecule is any one of the following compounds:

4. Use of the functional group-modified fused ring / aromatic ring molecule containing heteropolycoordinate atoms according to any one of claims 1 to 3 as an extraction agent for actinide elements.

5. The use according to claim 4, characterized in that: The actinide element is Np(V).

6. The use according to claim 4 or 5, characterized in that: The functional group-modified condensed ring / aromatic ring molecules containing heteropoly-coordinated atoms are used as actinide extraction reagents in the fields of radioactive waste liquid separation and nuclear fuel cycle.

7. A method for directly extracting Np(V), comprising the steps of: The functional group-modified condensed ring / aromatic ring molecule containing heteropolycoordinating atoms according to any one of claims 1 to 3 is dissolved in an organic solvent to obtain an organic phase; the organic phase is directly mixed with an acidic aqueous solution containing Np(V), and after the two phases are balanced, the phases are separated by centrifugation to achieve the extraction of neptunium.

8. The method according to claim 7, characterized in that The organic solvent includes any one or a mixture of cycloalkanes, fatty alcohols, ketones, and aromatic compounds; The concentration range of the functional group-modified condensed ring / aromatic ring molecules containing heteropoly coordinated atoms in the organic phase is 10 -4 -1mol / L; The acidic aqueous solution includes an aqueous perchloric acid solution, an aqueous nitric acid solution, an aqueous sulfuric acid solution, an aqueous hydrochloric acid solution, and an aqueous phosphoric acid solution; The acidity range of the aqueous solution is 10 -5 -14mol / L; The concentration range of Np ions in the aqueous solution is 10 -8 -10 -3 mol / L.

9. The method according to claim 7 or 8, characterized in that: The volume ratio of the two phases is any ratio within the range of 1:10-10:1; The two-phase mixing time is 1-360min; The centrifugal conditions are: 3000-5000 rpm, 1-5 min.

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