A 177 Method for separating Hf enrichment

Abstract

Disclosed is a kind of 177 A method for separating Hf isotopes, the method comprising: preparing a feed phase and an accept phase, respectively, placing the feed phase and the accept phase on both sides of a cation exchange membrane, applying a voltage, and performing 177 Extraction separation and recovery of Hf isotopes; the feed phase includes hafnium ions; the cation exchange membrane contains an extractant. The present application greatly shortens the time required to reach extraction equilibrium by using an electrodialysis device for cascade separation of Hf isotopes.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical coupling extraction and separation technology, specifically relating to a... 177 Methods for Hf enrichment and separation. Background Technology

[0002] Hafnium (Hf) has 174,176-180 Six stable isotopes of Hf. Enrichment 177 Hf isotopes hold significant strategic value in the nuclear industry. In nuclear production, the burnup rate of combustible poisons is a crucial factor affecting the long-term operation of reactors. Control rods made from naturally occurring Hf in-reactor combustible poisons suffer from poor fuel economy at the end of their lifespan due to reactivity penalties. Therefore, if Hf is used as a combustible poison, its total content must be limited. To address this issue, isotope-enriched Hf is used... 177 Hf isotopes, particularly Hf, can be used to create in-reactor combustible poisons that can reduce the amount of dispersed combustible poisons, thus lessening their impact on fuel pellet performance. 177 Hf isotope control rods result in a smoother reactivity profile throughout the reactor's lifespan, which is beneficial for reactivity control. They also significantly improve the residual combustible poison at the end of the reactor's lifespan, enhancing core fuel economy. (The text then abruptly shifts to a seemingly unrelated topic: using enrichment...) 177 Hf isotopes can be used to manufacture control rods for military reactors with superior neutron control performance, reducing the amount and weight of neutron control materials in military reactors, improving core structure, and designing long-life military reactor cores. However, to date, efficient separation and enrichment methods have not been discovered. 177 Methods using Hf isotopes. Summary of the Invention

[0003] To address the aforementioned technical problems, the present invention provides... 177 A method for separating Hf isotopes, the method comprising:

[0004] The feed phase and acceptor phase were prepared separately, placed on opposite sides of a cation exchange membrane, and a voltage was applied to perform... 177 Extraction, separation and recovery of Hf isotopes;

[0005] The supply phase includes hafnium ions;

[0006] The cation exchange membrane contains an extractant, the structure of which is as follows:

[0007]

[0008] According to an embodiment of the present invention, the voltage is 5-20V, preferably 6-12V.

[0009] According to an embodiment of the invention, the source of the hafnium ions is, for example, hafnium tetrachloride, and the hafnium ions have six stable isotopes. 174 Hf, 176 Hf, 177 Hf, 178 Hf, 179 Hf, 180 Hf.

[0010] According to an embodiment of the present invention, the volume ratio of the supply phase to the receiving phase is, for example, 1:1.

[0011] According to an embodiment of the present invention, the extraction time is 10-40 min, preferably 20-30 min.

[0012] According to an embodiment of the present invention, the extractant is prepared by mixing and reacting diethanol anhydride and diisooctylamine in an organic solvent to obtain the extractant.

[0013] According to an embodiment of the present invention, the mass ratio of diethanol anhydride to diisooctylamine is 1:0.5-20, preferably 1:1-10.

[0014] According to an embodiment of the present invention, the organic solvent is selected from at least one of CH2Cl2, n-dodecane, and kerosene. In this invention, the content of the organic solvent is not particularly limited, as long as it is sufficient to completely or partially dissolve glycolic anhydride and / or diisooctylamine.

[0015] According to an embodiment of the present invention, the reaction temperature during the preparation of the extractant is 15-50°C, for example, room temperature, and the reaction time during the preparation of the extractant is 2-48 h, preferably 6-20 h.

[0016] According to an embodiment of the present invention, the extractant is N,N-bis(2-ethylhexyl)diglycine, denoted as D2EHDGAA.

[0017] According to an embodiment of the present invention, the extractant is modified with any one of the functional groups selected from hydroxyl, carboxyl, amino, and nitro groups.

[0018] According to an embodiment of the present invention, the extractant is hydrophobic.

[0019] According to an embodiment of the present invention, the extractant has stability and extraction performance at room temperature and in acidic solutions.

[0020] According to an embodiment of the present invention, the method for preparing the extractant further includes a post-treatment step: washing, adsorption, and distillation of the prepared product. For example, washing may be performed using sulfuric acid or water, or, for example, adsorption may be performed using activated carbon. For instance, the obtained product is washed five times in a separation funnel with 0.1 mol / L H₂SO₄ and deionized water, respectively, and excess impurities are adsorbed using activated carbon. Finally, the solvent and water are removed using a rotary evaporator and a drying oven.

[0021] As an exemplary embodiment of the present invention, the method for preparing the extractant specifically includes the following steps:

[0022] Diethanol anhydride was added to CH2Cl2, and diisooctylamine dissolved in CH2Cl2 was added. The mixture was stirred with a magnetic stirrer at 500 rpm for 12 hours at room temperature to prepare the extractant.

[0023] According to an embodiment of the present invention, the cation exchange membrane includes an ionic liquid supported membrane (SILM membrane), a polymer-coated membrane (PIM membrane), or an ion-imprinted membrane (IIM membrane).

[0024] According to an embodiment of the present invention, the method for preparing the cation exchange membrane includes:

[0025] The cation exchange membrane is prepared by immersing a polyvinylidene fluoride (e.g., HVHP) membrane in an extractant solution.

[0026] According to an embodiment of the present invention, the extractant solution is prepared by dissolving the extractant in an ionic liquid, wherein the ionic liquid is selected from [C]. n mim][Tf2N]、[C n At least one of [mim][PF6], [C2mim][BF4], etc., wherein n is selected from at least one of 2-16.

[0027] According to an embodiment of the present invention, the concentration of the extractant solution is 10-40 mM, preferably 15-25 mM.

[0028] According to an embodiment of the present invention, the method for preparing the supply phase is as follows: adjusting the pH of the hafnium tetrachloride solution to acidic to obtain the supply phase.

[0029] According to an embodiment of the present invention, the acidity refers to a pH of 1-5, preferably 1.5. Adjusting the pH to acidity can improve the selectivity of the extractant for Hf isotopes.

[0030] According to an embodiment of the present invention, the concentration of the hafnium tetrachloride solution is 5ppm-60ppm, preferably 10ppm-30ppm.

[0031] According to an embodiment of the present invention, the method for preparing the supply phase specifically comprises:

[0032] Hafnium tetrachloride was dissolved in water, and then hydrochloric acid was added. The pH was adjusted to 1.5 using ammonia to obtain the feed phase. Exemplarily, the concentration of hydrochloric acid was 0.5 M. Also exemplary, the volume of the feed phase solution was 35 ml.

[0033] According to an embodiment of the present invention, the acceptor phase is prepared by dissolving diethylene glycol in sulfuric acid and water to obtain the acceptor phase.

[0034] According to an embodiment of the present invention, the concentration of the diethylene glycol is 0.05M-2M, for example, 1M.

[0035] According to an embodiment of the present invention, the sulfuric acid concentration is 0.05M-2M, for example, 1M.

[0036] According to an embodiment of the present invention, the method for preparing the acceptor phase specifically involves dissolving diethylene glycol in concentrated sulfuric acid and diluting with ultrapure water to obtain the acceptor phase. Exemplarily, the volume of the acceptor phase solution is 35 ml.

[0037] The beneficial effects of this invention are:

[0038] (1) The extractant of the present invention is simple to prepare and low in cost, and can be used for enrichment and separation. 177 Hf isotopes, and for 177 Hf has high selectivity.

[0039] (2) The extractant of the present invention has multiple active sites, which can improve the selectivity of isotope separation by the specific binding of functional groups to Hf isotopes, and is more environmentally friendly than traditional acid proton exchangers.

[0040] (3) In the separation method of the present invention, Hf isotope ions combine with the extractant to form complexes. Under the action of an external electric field, the differences in electromigration properties between different complexes can increase... 177 The separation coefficient of Hf increases 177 Hf selectivity, improve 177 The effect of Hf isotope separation and enrichment.

[0041] (4) The present invention uses an electrodialysis device to perform cascade separation of Hf isotopes, which greatly shortens the time required to reach extraction equilibrium.

[0042] (5) The separation efficiency can be increased by adjusting the eb-electrodialysis coupled extraction system. 177 Hf selectivity, improve 177 The effect of Hf isotope separation and enrichment. Attached Figure Description

[0043] Figure 1This is the infrared spectrum of D2EHDGAA from Example 1.

[0044] Figure 2 This is the hydrogen nuclear magnetic resonance spectrum of D2EHDGAA from Example 1.

[0045] Figure 3 The following are examples from Example 1: (a) a blank PVDF membrane; (b) a SILM using D2EHDGAA as the extractant and [C4mim][Tf2N] as the solvent; and (c) a SILM using D2EHDGAA as the extractant and [C2mim][Tf2N] as the solvent.

[0046] Figure 4 It is the extraction rate of Hf by the SILM membrane impregnated with D2EHDGAA in Example 2.

[0047] Figure 5 The content of Hf isotopes in the supply and receiving phases after different extraction times of the SILM membrane impregnated with D2EHDGAA in Example 2.

[0048] Figure 6 The content of Hf isotopes and the natural abundance of Hf isotopes in the supply and receiving phases after 30 min of extraction with a SILM membrane impregnated with D2EHDGAA in Example 2. Detailed Implementation

[0049] The following will provide a more detailed description of the technical solution of the present invention in conjunction with specific embodiments, based on the implementation scheme of the present invention. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0050] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0051] The specific implementation methods for the synthesis of D2EHDGAA extractant, the characterization and testing of various properties of the eb-electrodialysis coupled D2EHDGAA extraction and separation system, and its adsorption of 177Hf isotope, as mentioned in this invention, are as follows:

[0052] Example 1

[0053] The extractant (D2EHDGAA) of this invention was synthesized using a chemical synthesis method, and the specific implementation steps are as follows:

[0054] 13.9 g of diethylene glycol anhydride was added to a round-bottom flask and dissolved in 40 mL of CH2Cl2. After stirring until homogeneous, 24.1 g of diisooctylamine dissolved in 20 mL of CH2Cl2 was carefully added dropwise, and the mixture was stirred at 500 rpm with a magnetic stirrer at room temperature for 12 h. The resulting solution was purified to remove unreacted amine. The solution was added to a separatory funnel and washed five times with 0.1 mol / L H2SO4. The lower layer was collected and washed five times with deionized water. 2 g of activated carbon was added to the lower layer and stirred for 4 h to adsorb excess impurities. The resulting solution was filtered through a funnel, and the solvent dichloromethane was removed by rotary evaporation. Finally, the solution was dried to remove water, and the resulting product was a golden-yellow viscous liquid.

[0055] Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance (NMR) were used. 1 The newly synthesized N,N-di(2-ethylhexyl)-diacylamino acid (D2EHDGAA) extractant was analyzed by ¹H NMR, and the characterization chromatogram is shown below. Figure 1 and Figure 2 As shown, the FT-IR analysis results are consistent with the compound structure. 1 H (500MHz, CDCl3), the solvent peak is located at 7.373 in the spectrum. Furthermore, by setting the integral of one of the main peaks to 1, the integral of the adjacent impurity peaks is observed to be 0.0051, indicating that the purity of the extractant D2EHDGAA is greater than 98%.

[0056] A method for preparing an ionic liquid supported liquid film (SILM), the method comprising the following steps:

[0057] The extractant was dissolved in ionic liquids ([C₂mim][Tf₂N] and [C₄mim][Tf₂N], respectively) at a concentration of 25 mM. A PVDF (HVHP04700, pore size 0.45 μm, diameter 47 mm, thickness 125 μm) was immersed in 0.5 mL of the above solution, sealed, and allowed to stand for 12 h. After removal, the residual organic phase on the membrane surface was gently wiped away with filter paper, thus preparing an ionic liquid supported liquid membrane (SILM).

[0058] Figure 3 The images are SEM images of (a) the PVDF blank membrane, (b) the SILM with D2EHDGAA as the extractant and [C4mim][Tf2N] as the ionic liquid, and (c) the SILM with D2EHDGAA as the extractant and [C2mim][Tf2N] as the ionic liquid in Example 1. Figure 3 (a) The PVDF blank film exhibits a non-uniform crack structure. From... Figure 3 (b) It can be seen that SILM with [C2mim][Tf2N] as the solvent is uniform and dense, and the pores are also uniformly distributed. Figure 3 (c) It can be seen that SILM is a dense membrane with fewer and larger pores. This is due to the structure of the ionic liquid. The ionic liquid enters the pores of PVDF and adheres to the pore walls. When hafnium ions pass through, they undergo selective complexation extraction, thereby providing a channel for Hf isotope ion transport. Furthermore, compared to the blank PVDF membrane, the membrane impregnated with the ionic liquid has a rougher surface. The presence of the ionic liquids [C₂mim][Tf₂N] and [C₄mim][Tf₂N] minimizes the intermolecular forces within the polymer scaffold, resulting in higher membrane permeability.

[0059] Example 2:

[0060] A sort of 177 The enrichment and separation method for Hf includes the following steps:

[0061] (1) Preparation of the supply phase: Hafnium tetrachloride (99.99%) was added to ultrapure water to dissolve slowly, filtered, and then hydrochloric acid was added. The pH was adjusted to 1.5 with ammonia water. The concentration of hydrochloric acid was 0.5M, the concentration of hafnium ions was 10ppm, and the volume of the supply phase solution was 35ml.

[0062] (2) Prepare the acceptor phase; weigh diethylene glycol, add diluted concentrated sulfuric acid, and make up to volume with ultrapure water. The volume of the acceptor phase solution is 35 ml. The concentration of diethylene glycol in the acceptor phase solution is 0.1 M, and the concentration of sulfuric acid is 0.1 M.

[0063] (3) Using HVHP as a carrier, D2EHDGAA extractant dissolved in [C2mim] ionic liquid was impregnated. The concentration of the extractant in the ionic liquid was 25 mM. A SILM membrane was prepared, and the supply phase and acceptor phase were placed on opposite sides of the cation exchange membrane, respectively. A voltage of 20 V was applied, and the process was carried out. 177 Extraction, separation and recovery of Hf isotopes.

[0064] The extraction rate after 7 hours of electrodialysis extraction is as follows: Figure 4 As shown, the extraction rate in the receiving phase reached 68.18% after 7 hours of extraction.

[0065] Before and after 7 hours of electrodialysis coupled extraction, Hf isotopes in the feed and receiver phases were analyzed using ICP-MS. 174 Hf, 176 Hf, 177 Hf, 178 Hf, 179 Hf, 180 The content of Hf was tested (e.g.) Figure 5As shown in the figure, after 30 minutes of extraction, the separation coefficient of Hf isotopes has reached its maximum value, which means that the extraction efficiency of Hf isotopes in this invention is better than that of the electrodialysis-free coupled extraction system.

[0066] Figure 6 The changes in Hf isotope content before and after 30 minutes of electrodialysis coupled extraction are shown in the sample supply phase before and after extraction. 177 Hf / Natural Abundance 177 Hf = 1.011, receiving phase 177 Hf / Natural Abundance 177 Hf = 0.977. 177 The Hf isotope single-stage fractionation efficiency reached 1.035.

[0067] This invention uses HVHP as a carrier to prepare a SILM membrane containing an extractant, and then uses electrodialysis coupled with extraction to... 177 Hf isotopes undergo specific adsorption, and experiments demonstrate that this invention achieves... 177 It has great practical potential in Hf enrichment and separation.

[0068] The embodiments of the present invention have been described above by way of example. However, the scope of protection of the present invention is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made by those skilled in the art within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A kind 177 The method for separating Hf isotopes is characterized by, The method includes: The feed phase and acceptor phase were prepared separately, placed on opposite sides of a cation exchange membrane, and a voltage was applied to perform... 177 Extraction, separation and recovery of Hf isotopes; The supply phase includes hafnium ions; The cation exchange membrane contains an extractant, the structure of which is as follows: The voltage is 5-20V; The hafnium ions are derived from hafnium tetrachloride and have six stable isotopes. 174 Hf, 176 Hf, 177 Hf, 178 Hf, 179 Hf, 180 Hf.

2. The method according to claim 1, characterized in that, The cation exchange membrane includes an ionic liquid-supported membrane, a polymer-coated membrane, or an ion-imprinted membrane.

3. The method according to claim 1, characterized in that, The method for preparing the cation exchange membrane includes: immersing a polyvinylidene fluoride membrane in an extractant solution to obtain the cation exchange membrane.

4. The method according to claim 3, characterized in that, The extractant solution is prepared by dissolving the extractant in an ionic liquid, wherein the ionic liquid is selected from [C]. n mim][Tf2N]、[C n At least one of [mim][PF6] and [C2mim][BF4], wherein n is selected from at least one of 2-16; The concentration of the extractant solution is 10-40 mM.

5. The method according to claim 1, characterized in that, The method for preparing the supply phase is as follows: the pH of the hafnium tetrachloride solution is adjusted to acidity to obtain the supply phase.

6. The method according to claim 5, characterized in that, The concentration of the hafnium tetrachloride solution is 5 ppm to 60 ppm.

7. The method according to claim 1, characterized in that, The acceptor phase is prepared by dissolving diethylene glycol in sulfuric acid and water to obtain the acceptor phase.

8. The method according to claim 7, characterized in that, The concentration of the diethylene glycol is 0.05M-2M.

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