A kind of amide extractant and its preparation method and use

Abstract

The invention discloses an amide extractant and a preparation method and application thereof. The invention adopts a two-step method to obtain bisamide extractants 2,2'-(cyclohexane-1,2-dialkylbis(oxy))bis(N,N-dioctyl acetamide) (Octy-CDA) and 2,2'-(cyclohexane-1,2-dialkylbis(oxy))bis(N,N-bis(2-ethylhexyl)acetamide) (2-ethylhexyl-CDA). The raw materials for preparing the amide extractant are easy to obtain, the reaction is carried out at normal temperature and pressure, and the reaction process is clean and environmentally friendly. The bisamide extractant of the invention has both ether oxygen bonds and carbonyl oxygen bonds in its structure, thereby providing more binding sites for the extraction of plutonium and improving the coordination ability. The amide extractant of the invention is convenient for disposing of waste after plutonium extraction, thereby reducing environmental pollution.

Description

Technical Field

[0001] The invention belongs to the technical field of extractants, and specifically relates to an amide extractant and a preparation method and application thereof. Background Art

[0002] Plutonium is an important nuclear fuel and also a highly toxic and radioactive transuranic element. It plays an important role in the nuclear fuel cycle and radioactive waste disposal process. After the nuclear reaction is over, the spent fuel discharged from the reactor still contains about 95% uranium, 1% plutonium and 4% other fission products. Therefore, the separation and extraction of uranium and plutonium in spent fuel is one of the important steps in the reprocessing process.

[0003] Solvent extraction has gradually become the main method in spent fuel reprocessing due to its high flexibility, continuous operation, ability to withstand high radiation doses, and easy solvent regeneration and reuse. The PUREX Process is one of the most widely used, most effective and most successful spent fuel reprocessing processes. It uses solvent extraction and tributyl phosphate (TBP) as an extractant to separate and purify U(VI) and Pu(IV) from the initial high-concentration nitric acid solution on an industrial scale.

[0004] The use of TBP has been widely recognized, but it also has some limitations. It has high viscosity and a density close to that of water, which makes phase separation difficult and requires the use of diluents. In addition, if organic waste liquid containing TBP is not completely incinerated, phosphorus-containing radioactive solid waste will be produced. Under irradiation conditions, the degradation products of TBP, dibutyl phosphate (DBP) and monobutyl phosphate (MBP), have strong coordination ability for fission elements such as zirconium and niobium. The extraction process involving TBP often forms three phases. Therefore, for the separation of plutonium in the spent fuel reprocessing process, the existing extractants may not be able to achieve a high extraction distribution ratio or high selectivity. Although the performance of some extractants can be optimized by acid adjustment, the operation steps in the acid adjustment process are cumbersome and not suitable for subsequent industrial applications. Summary of the invention

[0005] In view of the above technical problems existing in the prior art, the object of the present invention is to provide an amide extractant with a wide acidity application range and high selectivity for Pu(IV), and to realize the extraction and separation of plutonium in the post-treatment process, and a preparation method thereof.

[0006] To achieve the above-mentioned purpose, the technical scheme adopted by the present invention is as follows: an amide extractant, wherein the amide extractant is a polyether oxygen bisamide extractant, 2,2'-(cyclohexane-1,2-dialkylbis(oxy))bis(N,N-dioctyl acetamide) (Octy-CDA), 2,2'-(cyclohexane-1,2-dialkylbis(oxy))bis(N,N-bis(2-ethylhexyl)acetamide) (2-ethylhexyl-CDA), and its structural formula is:

[0007]

[0008] Furthermore, the present invention also provides a method for preparing the amide extractant, comprising the following steps:

[0009] (1) dissolving an appropriate amount of dioctylamine in dichloromethane, adding potassium carbonate, slowly adding chloroacetyl chloride dropwise, reacting for a certain period of time, adding water to dissolve the potassium carbonate, separating the organic phase, and obtaining the intermediate chloroacetyl dioctylamine;

[0010] (2) adding an appropriate amount of sodium hydride to anhydrous tetrahydrofuran, adding cyclohexanediol in portions, stirring at room temperature, dissolving the intermediate in anhydrous tetrahydrofuran, and slowly adding dropwise at room temperature; after stirring, filtering and drying by suction to obtain the bisamide extractant Octy-CDA.

[0011] Furthermore, in the step (1), the organic phase is washed with hydrochloric acid and brine, dried with anhydrous magnesium sulfate, and spin-dried to obtain the colorless and transparent intermediate.

[0012] Furthermore, in the step (2), diatomaceous earth is used for suction filtration, and the filtrate is spin-dried.

[0013] Furthermore, the present invention also provides another method for preparing the amide extractant, comprising the following steps:

[0014] (1) dissolving an appropriate amount of diisooctylamine in dichloromethane, adding potassium carbonate, slowly adding chloroacetyl chloride dropwise, reacting for a certain period of time, adding water to dissolve potassium carbonate, separating the organic phase, and obtaining the intermediate chloroacetyl dioctylamine;

[0015] (2) adding an appropriate amount of sodium hydride to anhydrous tetrahydrofuran, adding cyclohexanediol in portions, and stirring at room temperature; dissolving the intermediate in anhydrous tetrahydrofuran, and slowly adding dropwise at room temperature; after stirring, filtering and drying by suction to obtain the bisamide extractant 2-ethylhexyl-CDA.

[0016] Furthermore, the present invention also provides the use of the amide extractant, wherein the amide extractant is used for separating plutonium in a spent fuel reprocessing process.

[0017] The beneficial effects brought about by the technical scheme of the present invention are an amide extractant and a preparation method and use thereof; the present invention adopts a two-step method to obtain a bisamide extractant, the raw materials are easy to obtain, the reaction is carried out at normal temperature and pressure, and the reaction process is clean and environmentally friendly; the bisamide extractant of the present invention has an ether oxygen bond and a carbonyl oxygen bond in its structure, which provides more binding sites for the extraction of plutonium and improves the coordination ability; and the amide extractant of the present invention is convenient for disposing of waste after plutonium extraction, thereby reducing environmental pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 The synthetic flow chart of the amide extractants Octy-CDA and 2-ethylhexyl-CDA prepared in Examples 1 and 2 of the present invention;

[0019] Figure 2 This is the carbon spectrum of the amide extractant Octy-CDA prepared in Example 3 of the present invention;

[0020] Figure 3 This is the carbon spectrum of the amide extractant 2-ethylhexyl-CDA prepared in Example 3 of the present invention;

[0021] Figure 4 This is the hydrogen spectrum of the amide extractant Octy-CDA prepared in Example 4 of the present invention;

[0022] Figure 5 This is the hydrogen spectrum of the amide extractant 2-ethylhexyl-CDA prepared in Example 4 of the present invention;

[0023] Figure 6 The infrared spectrum of the amide extractant Octy-CDA prepared in the embodiment of the present invention;

[0024] Figure 7 This is the infrared spectrum of the amide extractant 2-ethylhexyl-CDA prepared in the embodiment of the present invention. DETAILED DESCRIPTION

[0025] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0026] Embodiment 1

[0027] The embodiment of the present invention provides an amide extractant, wherein the amide extractant is a polyether oxygen bisamide extractant, 2,2'-(cyclohexane-1,2-dialkylbis(oxy))bis(N,N-dioctylacetamide) (Octy-CDA), and its structural formula is:

[0028]

[0029] Refer to the attached Figure 1The present invention also provides a method for preparing an amide extractant, comprising the following steps:

[0030] (1) dissolving an appropriate amount of dioctylamine in dichloromethane, adding potassium carbonate, slowly adding chloroacetyl chloride dropwise, reacting for a certain period of time, adding water to dissolve the potassium carbonate, separating the organic phase, and obtaining the intermediate chloroacetyl dioctylamine;

[0031] (2) adding an appropriate amount of sodium hydride to anhydrous tetrahydrofuran, adding cyclohexanediol in portions, stirring at room temperature, dissolving the intermediate in anhydrous tetrahydrofuran, and slowly adding dropwise at room temperature; after stirring, filtering and drying by suction to obtain the bisamide extractant Octy-CDA.

[0032] Preferably, in the step (1), the organic phase is washed with hydrochloric acid and brine, dried with anhydrous magnesium sulfate, and spin-dried to obtain the colorless and transparent intermediate.

[0033] Furthermore, in the step (2), diatomaceous earth is used for suction filtration, the filtrate is dried by rotation, and a certain proportion of petroleum ether and ethyl acetate are passed through a column to obtain the amide extractant Octy-CDA.

[0034] The embodiment of the present invention also provides the use of the amide extractant, which is used for plutonium separation in the spent fuel reprocessing process.

[0035] Embodiment 2

[0036] The embodiment of the present invention provides an amide extractant, wherein the amide extractant is a polyether oxygen bisamide extractant, 2,2'-(cyclohexane-1,2-dialkylbis(oxy))bis(N,N-bis(2-ethylhexyl)acetamide) (2-ethylhexyl-CDA), and its structural formula is:

[0037]

[0038] Refer to the attached Figure 1 The present invention also provides a method for preparing an amide extractant, comprising the following steps:

[0039] (1) dissolving an appropriate amount of diisooctylamine in dichloromethane, adding potassium carbonate, slowly adding chloroacetyl chloride dropwise, reacting for a certain period of time, adding water to dissolve potassium carbonate, separating the organic phase, and obtaining the intermediate chloroacetyl dioctylamine;

[0040] (2) adding an appropriate amount of sodium hydride to anhydrous tetrahydrofuran, adding cyclohexanediol in portions, stirring at room temperature, dissolving the intermediate in anhydrous tetrahydrofuran, and slowly adding dropwise at room temperature; after stirring, filtering and drying by suction to obtain an amide extractant 2-ethylhexyl-CDA.

[0041] The rest is the same as in the first embodiment.

[0042] Embodiment 3

[0043] The amide extractants Octy-CDA and 2-ethylhexyl-CDA were prepared by the methods of Examples 1 and 2 of the present invention, and dioctylamine and diisooctylamine were respectively dissolved in dichloromethane to prepare solutions with a concentration of about 120 g / L, and potassium carbonate was added to the dichloromethane solution with a concentration of about 68 g / L, and chloroacetyl chloride was slowly added dropwise in small amounts. After reacting for 30 minutes, a small amount of water was slowly added dropwise, and then an equal volume of water was quickly added to dissolve potassium carbonate, and the organic phase was separated. The organic phase was washed with 2 mol / L hydrochloric acid 3 times and saturated brine 2 times. The organic phase was dried over anhydrous magnesium sulfate and spin-dried to obtain a colorless transparent liquid, and the intermediates chloroacetyl dioctylamine and chloroacetyl diisooctylamine were obtained, respectively.

[0044] Sodium hydride was added to anhydrous tetrahydrofuran to prepare a solution with a concentration of about 63 g / L, and cyclohexanediol was added in batches to a solution with a tetrahydrofuran concentration of about 73 g / L, and stirred at room temperature for 30 minutes. Chloroacetyl dioctylamine and chloroacetyl diisooctylamine were dissolved in anhydrous tetrahydrofuran with a concentration of about 275 g / L, and slowly dripped into the reaction system at room temperature, and stirred overnight. Filtered with diatomaceous earth, the filtrate was dried by rotary evaporation, and passed through a column with petroleum ether: ethyl acetate 20:1 to obtain the products Octy-CDA and 2-ethylhexyl-CDA.

[0045] The rest is the same as in Embodiments 1 and 2.

[0046] Embodiment 4

[0047] The amide extractants Octy-CDA and 2-ethylhexyl-CDA were prepared by the method of Example 1 of the present invention. Dioctylamine and diisooctylamine were dissolved in dichloromethane to prepare a solution with a concentration of about 120 g / L. Potassium carbonate was added to the solution with a dichloromethane concentration of about 72 g / L, and chloroacetyl chloride was slowly added dropwise in small amounts to a concentration of 56 g / L. After reacting for 30 minutes, a small amount of water was slowly added dropwise, and then an equal volume of water was quickly added to dissolve potassium carbonate. The organic phases were separated, and the organic phases were washed 3 times with 2 mol / L hydrochloric acid and 2 times with saturated brine. The organic phases were dried over anhydrous magnesium sulfate and spin-dried to obtain a colorless transparent liquid, and the intermediates dioctyl chloroacetylamine and diisooctyl chloroacetylamine were obtained respectively.

[0048] Sodium hydride was added to anhydrous tetrahydrofuran to prepare a solution with a concentration of about 63 g / L, and cyclohexanediol was added in batches to a solution with a tetrahydrofuran concentration of about 73 g / L, and stirred at room temperature for 30 minutes. Chloroacetyl dioctylamine and chloroacetyl diisooctylamine were dissolved in anhydrous tetrahydrofuran with a concentration of about 275 g / L, and slowly dripped into the reaction system at room temperature, and stirred overnight. Filtered with diatomaceous earth, the filtrate was dried by rotary evaporation, and passed through a column with petroleum ether: ethyl acetate 20:1 to obtain extractants Octy-CDA and 2-ethylhexyl-CDA.

[0049] The rest is the same as in Embodiments 1 and 2.

[0050] Refer to the attached Figures 2 to 7 , indicating that Octy-CDA and 2-ethylhexyl-CDA prepared by the method of the embodiment of the present invention have ether oxygen bonds and carbonyl oxygen bonds, which provide more binding sites for the extraction of plutonium and effectively improve the coordination ability.

[0051] Embodiment 5

[0052] The amide extractant is prepared by replacing dioctylamine with amines having other carbon branches using the methods of Examples 1 and 2 of the present invention, thereby obtaining diamide extractants having different branched structures.

[0053] Embodiment 6

[0054] 1 ml of the amide extractant of the present invention, 0.1 mol / L Octy-CDA and 2-ethylhexyl-CDA were dissolved in n-dodecane, and then contacted with an equal volume of 10 mg / L Pu (IV) aqueous solution containing 3 mol / L nitric acid, and shaken in a constant temperature oscillator for 15 minutes (25° C.). The concentration of Pu (IV) was measured in the aqueous phase and the organic phase, and the extraction distribution ratio D was calculated. Pu .

[0055] D Pu The calculation formula is:

[0056]

[0057] Among them, C o represents the concentration of Pu(IV) in the organic phase, C a represents the concentration of Pu(IV) in the aqueous phase.

[0058] The calculated D values ​​of the Octy-CDA and 2-ethylhexyl-CDA extractants are Pu 5.1 and 3 respectively.

[0059] Embodiment 7

[0060] 1 ml of the amide extractant of the present invention, 0.1 mol / L Octy-CDA and 2-ethylhexyl-CDA were dissolved in n-dodecane, and then contacted with an equal volume of 10 mg / L Pu (IV) aqueous solution containing 5 mol / L nitric acid, and shaken in a constant temperature oscillator for 15 minutes (25° C.). The concentration of Pu (IV) in the aqueous phase and the organic phase was measured, and the extraction distribution ratio D was calculated. Pu The rest is the same as in Example 6.

[0061] Embodiment 8

[0062] 1 ml of the amide extractant of the present invention, 0.1 mol / L Octy-CDA and 2-ethylhexyl-CDA were dissolved in n-dodecane, and then contacted with an equal volume of 10 mg / L Pu (IV) aqueous solution containing 3 mol / L nitric acid, and shaken in a constant temperature oscillator for 15 minutes (25° C.). The concentration of Pu (IV) was measured in the aqueous phase and the organic phase, and the extraction distribution ratio D was calculated. Pu The rest is the same as in Example 6.

[0063] Embodiment 9

[0064] 1 ml of the amide extractant of the present invention, 0.1 mol / L Octy-CDA and 2-ethylhexyl-CDA were dissolved in n-dodecane, and then contacted with an equal volume of 10 mg / L Pu (IV) aqueous solution containing 3 mol / L nitric acid, and shaken in a constant temperature oscillator for 15 minutes (25° C.). The concentration of Pu (IV) was measured in the aqueous phase and the organic phase, and the extraction distribution ratio D was calculated. Pu The rest is the same as in Example 6.

[0065] Embodiment 10

[0066] 1 ml of the amide extractant of the present invention, 0.1 mol / L Octy-CDA and 2-ethylhexyl-CDA were dissolved in n-dodecane, and contacted with an equal volume of an aqueous solution of U(VI), Am(III), and Ce(III) containing 3 mol / L nitric acid, and shaken in a constant temperature oscillator for 15 minutes (25° C.), and the concentrations of U(VI), Am(III), and Ce(III) were measured in the aqueous phase and the organic phase, and the separation factor SF was calculated. Pu / M The SF Pu / M The calculation formula is:

[0067]

[0068]

[0069] Among them, C′ o Indicates the concentration of U(VI), Am(III), and Ce(III) in the organic phase, C′ a Represents the concentration of U(VI), Am(III), and Ce(III) in the aqueous phase.

[0070] The SF of Octy-CDA and 2-ethylhexyl-CDA Pu / U 6.2 and 3.2 respectively; SF Pu / Am 4.4 and 10.5 respectively; SF Pu / Ce They are 30.2 and 15.3 respectively.

[0071] Embodiment 11

[0072] 1 ml of the amide extractant of the present invention, 0.1 mol / L Octy-CDA and 2-ethylhexyl-CDA were dissolved in n-dodecane, and contacted with an equal volume of an aqueous solution of U(VI), Am(III), and Ce(III) containing 5 mol / L nitric acid, and shaken in a constant temperature oscillator for 15 minutes (25° C.), and the concentrations of U(VI), Am(III), and Ce(III) were measured in the aqueous phase and the organic phase, and the separation factor SF was calculated. Pu / U 8.0 and 4.9 respectively; SF Pu / Am 3.9 and 8.4 respectively; SF Pu / Ce The rest is the same as in Example 10.

[0073] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. An amide extractant, characterized in that: The amide extractant is a polyether oxygen bisamide extractant, 2,2'-(cyclohexane-1,2-dialkylbis(oxy))bis(N,N-dioctyl acetamide) (Octy-CDA), and its structural formula is:

2. An amide extractant, characterized in that: The amide extractant is a polyether oxygen bisamide extractant, 2,2'-(cyclohexane-1,2-dialkylbis(oxy))bis(N,N-bis(2-ethylhexyl)acetamide) (2-ethylhexyl-CDA), and its structural formula is:

3. The method for preparing an amide extractant according to claim 1, characterized in that: The following steps are involved: (1) dissolving an appropriate amount of dioctylamine in dichloromethane, adding potassium carbonate, slowly adding chloroacetyl chloride dropwise, reacting for a certain period of time, adding water to dissolve the potassium carbonate, separating the organic phase, and obtaining the intermediate chloroacetyl dioctylamine; (2) adding an appropriate amount of sodium hydride to anhydrous tetrahydrofuran, adding cyclohexanediol in portions, stirring at room temperature, dissolving the intermediate in anhydrous tetrahydrofuran, and slowly adding dropwise at room temperature; after stirring, filtering and drying by suction to obtain the bisamide extractant Octy-CDA.

4. The method for preparing an amide extractant according to claim 2, characterized in that: The following steps are involved: (1) dissolving an appropriate amount of diisooctylamine in dichloromethane, adding potassium carbonate, slowly adding chloroacetyl chloride dropwise, reacting for a certain period of time, adding water to dissolve potassium carbonate, separating the organic phase, and obtaining the intermediate chloroacetyl dioctylamine; (2) adding an appropriate amount of sodium hydride to anhydrous tetrahydrofuran, adding cyclohexanediol in portions, stirring at room temperature, dissolving the intermediate in anhydrous tetrahydrofuran, and slowly adding dropwise at room temperature; after stirring, filtering and drying by suction to obtain an amide extractant 2-ethylhexyl-CDA.

5. The method for preparing an amide extractant according to claim 3 or 4, characterized in that: In the step (1), the organic phase is washed with hydrochloric acid and brine, dried with anhydrous magnesium sulfate, and spin-dried to obtain the colorless and transparent intermediate.

6. The method for preparing an amide extractant according to claim 3, characterized in that: In the step (2), diatomaceous earth is used for suction filtration, the filtrate is spin-dried, and a certain proportion of petroleum ether and ethyl acetate are passed through a column to obtain the amide extractant Octy-CDA.

7. The method for preparing an amide extractant according to claim 4, characterized in that: In the step (2), diatomaceous earth is used for suction filtration, the filtrate is spin-dried, and a certain proportion of petroleum ether and ethyl acetate are passed through a column to obtain an amide extractant 2-ethylhexyl-CDA.

8. The use of the amide extractant according to claim 1 or 2, characterized in that: The amide extractant is used for plutonium separation in the spent fuel reprocessing process.

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