阅读说明：本技术 从待测样品中分离镎的分离方法 (Separation method for separating neptunium from sample to be detected ) 是由 张曦 余振华 张生栋 杨素亮 杨志红 姚曜晖 于 2020-06-10 设计创作，主要内容包括：本发明的实施例提供了一种从待测样品中分离镎的分离方法,所述方法包括以下步骤：采用氟化氢铵作为溶解剂对所述待测样品进行溶解；将所述待测样品的溶解液与第一萃取剂接触,获得包含所述镎的有机相；将所述有机相与络合剂接触,获得包含所述镎的水相；通过第二萃取剂从所述水相中萃取镎；其中,所述第一萃取剂为双酰胺荚醚。本发明实施例的镎的分离方法适用于从岩石、土壤、河底沉积物样品中分离镎。根据本发明实施例的镎的分离方法,能够从含有大量干扰元素或离子的体系中富集痕量镎,提高镎的分离纯化效果,从而提高其检测分析精度。(An embodiment of the present invention provides a method for separating neptunium from a sample to be tested, the method comprising the steps of: dissolving the sample to be detected by adopting ammonium bifluoride as a dissolving agent; contacting the solution of the sample to be detected with a first extraction agent to obtain an organic phase containing the neptunium; contacting said organic phase with a complexing agent to obtain an aqueous phase containing said neptunium; extracting neptunium from the aqueous phase by means of a second extractant; wherein the first extraction agent is bisamide podophyllum ether. The method for separating the neptunium is suitable for separating the neptunium from rock, soil and river bottom sediment samples. According to the method for separating the neptunium, provided by the embodiment of the invention, the trace neptunium can be enriched from a system containing a large amount of interference elements or ions, and the separation and purification effects of the neptunium are improved, so that the detection and analysis precision of the neptunium is improved.)

1. A method for separating neptunium from a sample to be tested, said method comprising the steps of:

dissolving the sample to be detected by adopting ammonium bifluoride as a dissolving agent;

contacting the solution of the sample to be detected with a first extraction agent to obtain an organic phase containing the neptunium;

contacting said organic phase with a complexing agent to obtain an aqueous phase containing said neptunium;

extracting neptunium from the aqueous phase by means of a second extractant; wherein the content of the first and second substances,

the first extractant is bisamide pod ether.

2. The separation method according to claim 1,

the first extractant is N, N '-dimethyl-N, N' -dioctyl-3-oxa-glutaramide.

3. The separation method according to claim 2,

the second extractant is alpha-thiophene formyl trifluoroacetone.

4. The separation method according to claim 1, wherein the step of dissolving the sample to be measured using ammonium bifluoride as a main dissolution agent comprises:

and reducing the neptunium in the dissolving solution.

5. The separation method according to claim 4,

the reducing agent is selected from alkylated derivatives of hydrazine, alkylated derivatives of hydroxylamine, and ferrous sulfamate.

6. The separation method according to any one of claims 1 to 5, wherein,

the complexing agent is selected from glutaryl imminium dioxime, oxalic acid and disodium EDTA.

7. A method for separating neptunium from a sample to be tested, said method comprising the steps of:

dissolving the sample to be detected by adopting ammonium bifluoride as a dissolving agent;

carrying out neptunium enrichment extraction on the dissolved solution through a first extraction chromatographic column, and eluting neptunium through a complexing agent;

enabling the eluent obtained in the last step to pass through a second extraction chromatographic column to carry out neptunium purification; wherein the content of the first and second substances,

the first extraction chromatographic column is bisamide podophyllum ether.

8. The separation method according to claim 7,

the first extraction chromatographic column is DMDODGA/CMG 20.

9. The separation method according to claim 8,

the second extraction chromatographic column is DOWEX-1 × 4.

10. The separation method according to claim 9, wherein the step of dissolving the sample to be measured using ammonium bifluoride as a main dissolution agent comprises:

and reducing the neptunium in the dissolving solution.

11. The separation method according to claim 10, further comprising,

the neptunium was further purified by TTA extraction.

12. The separation method according to any one of claims 1 to 11, which is suitable for separating neptunium from rock, soil, river bottom sediment samples.

Technical Field

The invention relates to the technical field of radionuclide recovery, in particular to a separation method for separating neptunium from a sample to be detected.

Background

Isotope of transuranic neptunium²³⁷Np has a long half-life (2.14 × 10)⁶Year) and strong radioactive toxicity. The sources of neptunium in the environment include radioactive dust, nuclear leakage caused by nuclear power plant accidents, high-level radioactive waste deep geological disposal element migration, and the like. Because of its high radioactive toxicity, it is necessary to monitor the environment for neptunium.

Neptunium is present in very low amounts in environmental samples (e.g. rock samples), containing only feik to picogram per gram of environmental sample, and is usually detected by mass spectrometry. However, it is very difficult to separate enough neptunium from the rock, requiring the dissolution of tens or even hundreds of grams of rock; the traditional inorganic acid dissolution method is only suitable for milligram-scale rock dissolution, and can be realized by an ammonium bifluoride dissolution method for hectogram-scale rock dissolution.

However, the ammonium bifluoride solution system is relatively complex in composition, contains a large amount of fluorine ions and silicic acid, and also contains matrix elements in the rock and other elements with chemical properties similar to those of neptunium, and the content of the elements is far higher than that of the neptunium (higher than 10 percent)⁸Of the order of magnitude above) these components would be a serious nuisance for the isolated detection of neptunium. Moreover, the chemical behavior of neptunium in such a complex medium is greatly different from that of a single system, and the traditional methods such as TBP (tributyl phosphate) extraction, anion exchange and the like are difficult to efficiently recover the neptunium from the dissolved solution.

Based on the above problems, it is necessary to establish an effective separation and purification process to improve the separation efficiency of neptunium.

Disclosure of Invention

The embodiment of the invention provides a method for separating neptunium from a sample to be detected, and solves the problems of poor neptunium separation effect and inaccurate analysis in the related technology.

According to one aspect of the present invention, there is provided a method of isolating neptunium from a sample to be tested, the method comprising the steps of: dissolving the sample to be detected by adopting ammonium bifluoride as a dissolving agent; contacting the solution of the sample to be detected with a first extraction agent to obtain an organic phase containing the neptunium; contacting said organic phase with a complexing agent to obtain an aqueous phase containing said neptunium; extracting neptunium from the aqueous phase by means of a second extractant; wherein the first extraction agent is bisamide podophyllum ether.

In some embodiments, the first extractant is N, N '-dimethyl-N, N' -dioctyl-3-oxa-glutaramide.

In some embodiments, the second extractant is α -thenoyltrifluoroacetone.

In some embodiments, the step of dissolving the sample to be tested using ammonium bifluoride as a dissolving agent comprises: and reducing the neptunium in the dissolving solution.

In some embodiments, the reducing agent is selected from alkylated derivatives of hydrazine, alkylated derivatives of hydroxylamine, and ferrous sulfamate.

In some embodiments, the complexing agent is selected from glutaryl imminium dioxime, oxalic acid, and disodium EDTA.

According to another aspect of the present invention, there is provided a method of isolating neptunium from a sample to be tested, the method comprising the steps of: dissolving the sample to be detected by adopting ammonium bifluoride as a dissolving agent; separating uranium and neptunium from the dissolved solution through a first extraction chromatographic column, and eluting the neptunium through a complexing agent; enabling the eluent obtained in the last step to pass through a second extraction chromatographic column to carry out neptunium purification; wherein the first extraction chromatographic column is bisamide podophyllum ether.

In some embodiments, the first extraction chromatography column is DMDODGA/CMG 20.

In some embodiments, the second extraction chromatographic column is DOWEX-1X 4.

In some embodiments, the step of dissolving the sample to be tested using ammonium bifluoride as a dissolving agent comprises: and reducing the neptunium in the dissolving solution.

In some embodiments, the method further comprises further purifying the neptunium by TTA extraction.

According to an embodiment of the invention, the separation method is suitable for the separation of neptunium from rock, soil, river bottom sediment samples.

According to the separation method for separating the neptunium from the sample to be detected, provided by the embodiment of the invention, the ammonium bifluoride dissolving system is established to dissolve the sample to be detected, so that incomplete neptunium separation caused by the fact that target neptunium is contained in dissolving residues can be avoided; meanwhile, the optimized extraction and purification process is adopted, so that the yield of the neptunium can be further improved, and the accuracy of neptunium analysis is improved.

Drawings

Other objects and advantages of the present invention will become apparent from the following description of the invention which refers to the accompanying drawings, and may assist in a comprehensive understanding of the invention.

Fig. 1 is a flow chart of a method for the separation of neptunium from a sample to be tested according to one embodiment of the invention;

fig. 2 is a flow chart of a method of separation of neptunium from a sample to be tested according to another embodiment of the invention;

fig. 3 is a flow chart of a method of separation of neptunium from a sample to be tested according to another embodiment of the invention;

FIG. 4 is a schematic diagram comparing the partition coefficients of DMDODGA/CMG20 resin in different extraction systems according to an embodiment of the invention;

FIG. 5 is a schematic of a desorption peak elution profile using different complexed desorbents in accordance with an embodiment of the present invention.

It is noted that the drawings are not necessarily to scale and are merely illustrative in nature and not intended to obscure the reader.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be described clearly and completely with reference to the accompanying drawings of the embodiments of the present invention. It should be apparent that the described embodiment is one embodiment of the invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the described embodiments of the invention without any inventive step, are within the scope of protection of the invention.

Unless defined otherwise, technical or scientific terms used herein shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention belongs.

Referring to fig. 1 to 3, the method for separating neptunium from a sample to be detected according to the embodiment of the present invention can separate a trace amount of neptunium (e.g., picogram or feik neptunium/gram sample) in an environmental sample, thereby providing an advantageous basis for neptunium detection analysis. Since the neptunium content in the system to be separated is trace relative to other interfering elements or ions, if neptunium is to be accurately determined, the requirement for decontamination of the interfering elements or ions needs to be increased, and the neptunium yield needs to be increased, which can be achieved by establishing an efficient separation and purification process, for example.

Fig. 1 schematically shows a flow chart of a method for separating neptunium from a sample to be tested according to an embodiment of the invention.

As shown in FIG. 1, the method includes operations S10-S16.

In operation S10, a sample to be tested is dissolved using ammonium bifluoride as a dissolving agent.

In operation S12, the dissolution solution of the sample to be tested is contacted with the first extraction agent to obtain an organic phase containing neptunium.

In operation S14, the organic phase is contacted with a complexing agent to obtain an aqueous phase comprising neptunium.

In operation S16, the neptunium is extracted from the aqueous phase by the second extractant.

According to the embodiment of the invention, in operation S10, the ammonium bifluoride is used as a dissolving agent to dissolve the sample to be detected, so that not only can the sample to be detected be completely dissolved, but also the dissolving process can be performed under normal pressure without involving high pressure, thereby avoiding using hydrofluoric acid to reduce harm to human body, and having the advantages of safety, convenience in operation and the like.

Meanwhile, an ammonium bifluoride dissolving system is adopted, so that hundred-gram-magnitude sample dissolution can be realized, and quantitative recovery of trace neptunium in the sample is facilitated.

In operation S12, neptunium is extracted from an ammonium acid fluoride dissolution system using a first extractant. Because the composition of the ammonium bifluoride dissolving system is relatively complex, the traditional precipitation method, anion exchange method, TBP extraction and the like are difficult to realize the effective separation of the neptunium. Starting from the neptunium complexation mechanism, an effective separation process can be established.

According to an embodiment of the present invention, the first extractant employs bisamide pod ether. The bisamide pod ether has a tridentate coordination structure, and has stronger adsorption capacity on neptunium compared with a monodentate extraction agent and a bidentate extraction agent. Complex structural studies on bisamide podites have shown that the coordination sphere of the metal ion is completely occupied by ligands, each (bisamide podite) ligand being coordinated with a tridentate ligand through two carbonyl oxygen atoms and one ether oxygen atom. Meanwhile, the molecular structure of the phosphorus-containing extractant only contains C, H, O, N element, so that more harmful substances are not generated after incineration, and the phosphorus-containing extractant is favorable for reducing the amount of secondary waste compared with the common phosphorus-containing extractant.

Bisamide pods have both symmetrical and asymmetrical structures, depending on the substituents attached to the two amide groups N. In the asymmetric bisamide pod ether molecules, when short chain groups such as methyl and the like are connected to the amide N, steric hindrance of coordination participated by carbonyl can be reduced, so that the steric hindrance in the extraction process can be reduced, and meanwhile, when groups with stronger power supply such as long-chain alkyl, branched alkyl and the like are connected, the density of carbonyl oxygen electron cloud can be increased, thus being beneficial to extraction of neptunium, and the formation of a third phase in the extraction process can be avoided to a certain extent.

In a preferred embodiment, the first extractant is, for example, N '-dimethyl-N, N' -dioctyl-3-oxa-glutaramide (DMDODGA). The molecular structure of DMDODGA is shown in formula (I). According to the crystal bond length research, when methyl exists at N and N' positions in the asymmetric tetra-substituted alkyl, for example, the distance between two methyl groups is 4 angstroms, Np (IV) complexation is facilitated, and the Np (IV) complexation capacity is improved.

Further, in operation S14, the first extractant extraction is terminated, the organic phase is obtained by centrifugation, and neptunium is desorbed from the organic phase by the complexing agent.

According to an embodiment of the present invention, the complexing agent may be selected from any one of glutaryl-imminium dioxime, oxalic acid, and disodium EDTA, for example. For example, glutaryl-imino-dioxime is used as a complex desorbent, so that a good desorption effect can be obtained and the subsequent treatment steps can be simplified. Glutaryl amidoxime is a monofunctional group in a seawater uranium extraction macromolecular material, and a macromolecular polymeric material is mostly adopted for adsorption research in the research of seawater uranium extraction. According to the embodiment of the invention, functional groups in a macromolecular material are subjected to micromolecule treatment to obtain glutaryl imino dioxime, and the glutaryl imino dioxime is applied to complex desorption, so that an improved complex desorption effect can be obtained.

The embodiment of the invention does not limit the type of the complexing agent, and a proper complexing agent can be selected according to different extraction systems so as to improve the desorption of the neptunium.

Further, in operation S16, neptunium may be extracted again from the product obtained in the previous step to increase the yield of neptunium.

The second extractant is, for example, α -thenoyltrifluoroacetone (TTA). TTA has good extraction and separation capacity on IV-valence neptunium, and is favorable for further eliminating interfering elements or ions.

In order to extract and separate neptunium from the solution system with high efficiency, in operation S10, for example, a step of reducing neptunium in the solution is performed. For example, a reducing agent can be added into the solution to adjust the valence of the neptunium so as to stabilize the neptunium to the tetravalent state, thereby facilitating the neptunium coordination adsorption in the next procedure.

Reducing agents, according to embodiments of the present invention, include, for example, alkylated derivatives of hydrazine, alkylated derivatives of hydroxylamine, and ferrous sulfamate.

It is understood that the separation method for neptunium in the above embodiment is not limited to two-step extraction separation, and may also be multi-step extraction separation to improve the separation and purification of neptunium and improve the decontamination effect.

Fig. 2 schematically shows a flow chart of a method for separating neptunium from a sample to be tested according to another embodiment of the invention.

As shown in FIG. 1, the method includes operations S20-S24.

In operation S20, a sample to be tested is dissolved using ammonium bifluoride as a dissolving agent.

In operation S22, the solution is subjected to neptunium-enriched extraction through the first extraction chromatography column, and the neptunium is eluted through the complexing agent.

In operation S24, the eluate obtained in the previous step is passed through a second extraction chromatographic column to perform neptunium purification.

According to the embodiment of the invention, the neptunium is separated and extracted by adopting an extraction chromatography method. For the sample to be separated, such as a sample containing a large amount of uranium, a trace amount of neptunium and other interference elements, a part of uranium and various interference elements or ions can be removed through primary column separation, and then the sample is further decontaminated through secondary column separation, so that an enhanced decontamination effect can be shown, and neptunium in the product is purified, so that the high-purity neptunium recovery is realized, and the decontamination requirement in analysis is met.

In a preferred embodiment, the first extraction chromatographic column is, for example, DMDODGA/CMG 20; the second extraction chromatographic column is, for example, DOWEX-1X 4. DOWEX-1X 4 is a strong base anion exchange resin which has a strong detergency towards U and rock matrix elements, for example in a hydrochloric acid medium.

Further, in operation S20, for example, a step of reducing the neptunium in the dissolution solution is performed. For example, a reducing agent can be added into the solution to adjust the valence of the neptunium so as to stabilize the neptunium to the tetravalent state, thereby facilitating the neptunium coordination adsorption in the next procedure.

Fig. 3 schematically shows a flow chart of a method for separating neptunium from a sample to be tested according to another embodiment of the invention.

As shown in fig. 3, the separation method is compared with the separation method of fig. 2, in which operation S36 is added: the neptunium was further purified by TTA extraction for further decontamination.

Therefore, according to the neptunium separation method provided by the embodiment of the invention, the recovery effect of neptunium is improved through a multi-step column separation and purification process, the decontamination requirement on impurity elements in sample measurement is easily met, and the neptunium measurement precision is improved.

The neptunium separation method of the above embodiment is suitable for separating neptunium from environmental samples such as rock, soil, and river bottom sediment samples.

Specific examples are described below to help the skilled person to better understand the technical solution of the present invention.