CN114956215B - Perchloric acid system containing pentavalent neptunium ions and preparation method thereof - Google Patents
Perchloric acid system containing pentavalent neptunium ions and preparation method thereof Download PDFInfo
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Abstract
The invention provides a perchloric acid system containing pentavalent neptunium ions and a preparation method thereof. The organic solvent pyridine is used for replacing inorganic salt as a reducing agent to reduce hexavalent neptunium ions, and the pentavalent neptunium solid can be directly obtained after acetonitrile and pyridine in a reaction system are removed, so that the operation process is simple, and neptunium is basically completely recovered and no radioactive waste liquid is generated.
Description
Technical Field
The invention relates to the technical field of preparation of pentavalent neptunium, in particular to a perchloric acid system containing pentavalent neptunium ions and a preparation method thereof.
Background
Neptunium (Np) generally exists in aqueous solution in three valence states Np (IV), np (V), np (VI), where Np (V) is the most stable, most common valence state. The coordination behavior of Np (V) and inorganic anions or organic ligands can be studied to obtain information such as coordination constants, thermodynamic parameters and the like, so that the species distribution and migration behavior of Np (V) in an aqueous solution can be known. Since there is no coordination between the Np ions and perchlorate, a solution of perchloric acid containing Np is usually obtained first, wherein the preparation of the single valence Np (V) ions of the perchloric acid system is a primary technical difficulty.
The preparation of Np (V) solutions is generally a two-step process, where Np is oxidized to Np (VI) and then reduced to Np (V) using a reducing agent, commonly used oxidizing and reducing agents are perchloric acid and sodium nitrite, respectively. Although Np (V) solution with higher purity can be prepared, the operation is complicated and radioactive waste liquid is generated.
Disclosure of Invention
Based on the above, it is necessary to provide a perchloric acid system containing pentavalent neptunium ions which is simple to operate, does not generate radioactive waste liquid, and has high purity, and a preparation method thereof.
The method for preparing the perchloric acid system containing the pentavalent neptunium ions provided in the embodiment comprises the following steps:
pyridine is used as a reducing agent, hexavalent neptunium ions are reduced into pentavalent neptunium ions in acetonitrile, acetonitrile and pyridine in a reaction system are removed, and then perchloric acid solution is added to prepare a perchloric acid system containing the pentavalent neptunium ions.
In some embodiments, the method specifically comprises the following steps:
removing the solvent from the solution containing hexavalent neptunium ions to produce a first solid;
dissolving the first solid by adopting the acetonitrile to prepare a first solution;
adding the pyridine into the first solution to prepare the reaction system;
removing acetonitrile and pyridine in the reaction system to prepare a second solid;
and dissolving the second solid in the perchloric acid solution to prepare a perchloric acid system containing pentavalent neptunium ions.
In some embodiments, the mass ratio of neptunium element contained in said first solution to said pyridine is 1 (400-1300).
In some embodiments, the solution containing the hexavalent neptunium ions comprises one or more of a nitric acid solution containing the hexavalent neptunium ions and a perchloric acid solution containing the hexavalent neptunium ions.
In some embodiments, the molar concentration of the perchloric acid solution is from 0.1 to 2.0mol/L.
In some embodiments, further comprising determining whether the hexavalent neptunium ions contained in the first solution are completely reduced;
alternatively, when the reaction system is a bright green clear solution containing no precipitate, it is determined that the hexavalent neptunium ions contained in the first solution are completely reduced.
In some embodiments, the solvent in the solution containing the hexavalent neptunium ions is removed by heating at 90-140 ℃.
In some embodiments, acetonitrile and pyridine are removed from the reaction system by draining the solvent with stirring.
In some of these embodiments, the speed of agitation is 750-1200r/min.
An embodiment provides a perchloric acid system containing pentavalent neptunium ions, which is prepared by adopting the preparation method of the perchloric acid system containing pentavalent neptunium ions.
According to the perchloric acid system containing pentavalent neptunium ions and the preparation method thereof, pyridine is used as a reducing agent, hexavalent neptunium ions are reduced into pentavalent neptunium ions in acetonitrile, acetonitrile and pyridine in a reaction system are removed, and then perchloric acid solution is added to prepare the perchloric acid system containing pentavalent neptunium ions; the organic solvent pyridine is used for replacing inorganic salt as a reducing agent to reduce hexavalent neptunium ions, and the pentavalent neptunium solid can be directly obtained after acetonitrile and pyridine in a reaction system are removed, so that the operation process is simple, and neptunium is basically completely recovered and no radioactive waste liquid is generated.
Detailed Description
In order that the invention may be readily understood, a more particular description of the invention will be rendered by reference to specific embodiments that are illustrated in the appended drawings. Preferred embodiments of the present invention are given below. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.
It is understood that, in the technical features described in the open form herein, the closed technical solutions comprising the listed features are also included in the open technical solutions comprising the listed features.
Herein, "one or more" refers to any one or any two or a combination of any two or more of the listed items.
In this context, reference to a numerical interval is to be construed as continuous and includes the minimum and maximum values of the range, and each value between such minimum and maximum values, unless otherwise specified. Further, when a range refers to an integer, each integer between the minimum and maximum values of the range is included. Further, when multiple range description features or characteristics are provided, the ranges may be combined. In other words, unless otherwise indicated, all ranges disclosed herein are to be understood to include any and all subranges subsumed therein.
In this context, referring to units of data range, if a unit is only carried after the right endpoint, the units representing the left and right endpoints are identical. For example, 0.1 to 2.0mol/L means that the units of "0.1" at the left end and "2.0" at the right end are mol/L.
The temperature parameter herein is not particularly limited, and may be a constant temperature treatment or a treatment within a certain temperature range. The constant temperature process allows the temperature to fluctuate within the accuracy of the instrument control.
Neptunium (Np) generally exists in aqueous solution in three valence states Np (IV), np (V), np (VI), where Np (V) is the most stable, most common valence state. The coordination behavior of Np (V) and inorganic anions or organic ligands can be studied to obtain information such as coordination constants, thermodynamic parameters and the like, so that the species distribution and migration behavior of Np (V) in an aqueous solution can be known. Since there is no coordination between the Np ions and perchlorate, a solution of perchloric acid containing Np is usually obtained first, wherein the preparation of the single valence Np (V) ions of the perchloric acid system is a primary technical difficulty.
The preparation of Np (V) solutions is generally a two-step process, where Np is oxidized to Np (VI) and then reduced to Np (V) using a reducing agent, commonly used oxidizing and reducing agents are perchloric acid and sodium nitrite, respectively. The specific method comprises the following steps: solid NpO 2 Dissolving in concentrated perchloric acid, adding a few drops of concentrated hydrochloric acid, heating the solution to remove excessive perchloric acid and a small amount of hydrochloric acid after complete dissolution, wherein Np in the solution is oxidized to Np (VI), and the solution turns pink. To the pink solution of Np (VI) was added a small amount of sodium nitrite, the solution turned green and Np (VI) was reduced to Np (V). Subsequently 1mol/L sodium hydroxide is added into the solution to generate NpO 2 And (3) OH precipitation, centrifuging and repeatedly cleaning the precipitate with deionized water for three times to ensure that excessive sodium hydroxide is removed, and finally dissolving the precipitate with 1mol/L perchloric acid to obtain a perchloric acid solution containing Np (V). Although the above-mentioned method can obtain Np (V) solution with higher purity, it is cumbersome to operate, and radioactive waste liquid is generated, and in addition, the loss of Np is inevitably caused in the precipitation process.
To solve the above problems, an embodiment provides a method for preparing a perchloric acid system containing pentavalent neptunium ions, which may include: pyridine is used as a reducing agent, hexavalent neptunium ions are reduced into pentavalent neptunium ions in acetonitrile, acetonitrile and pyridine in a reaction system are removed, and then perchloric acid solution is added to prepare a perchloric acid system containing the pentavalent neptunium ions.
According to the preparation method, organic solvent pyridine is used for replacing inorganic salt to serve as a reducing agent to reduce hexavalent neptunium ions, and after acetonitrile and pyridine in a reaction system are removed, pentavalent neptunium solids can be directly obtained, the operation process is simple, neptunium is basically completely recovered, and no radioactive waste liquid is generated.
In some embodiments, the method specifically includes the following steps:
removing the solvent from the solution containing hexavalent neptunium ions to produce a first solid;
dissolving the first solid by adopting the acetonitrile to prepare a first solution;
adding the pyridine into the first solution to prepare the reaction system;
removing acetonitrile and pyridine in the reaction system to prepare a second solid;
and dissolving the second solid in the perchloric acid solution to prepare a perchloric acid system containing pentavalent neptunium ions.
It is understood that the first solid is a solid containing hexavalent neptunium; the first solution is a solution containing hexavalent neptunium ions, the reaction system is a solution containing pentavalent neptunium ions, and the second solid is a solid containing pentavalent neptunium ions.
The acetonitrile is preferably added in an amount to dissolve the first solid in its entirety, and the perchloric acid solution is preferably added in an amount to dissolve the second solid in its entirety.
In some of these embodiments, the mass ratio of neptunium element contained in said first solution to said pyridine may be 1 (400-1300); for example, it may be 1:400, 1:500, 1:600, 1:700, 1:800, 1:900, 1:1000, 1:1100, 1:1200, 1:1300, or 1:1400, etc., without limitation. When the mass ratio of neptunium element to pyridine in the first solution is 1 (400-1300), hexavalent neptunium ions in the first solution can be fully reduced.
In some embodiments, the solution containing hexavalent neptunium ions may include one or more of a nitric acid solution containing the hexavalent neptunium ions and a perchloric acid solution containing the hexavalent neptunium ions.
In some embodiments, the molar concentration of the perchloric acid solution may be 0.1 to 2.0mol/L; for example, the amount of the catalyst may be 0.1mol/L, 0.2mol/L, 0.3mol/L, 0.4mol/L, 0.5mol/L, 0.6mol/L, 0.7mol/L, 0.8mol/L, 0.9mol/L, 1.0mol/L, 1.1mol/L, 1.2mol/L, 1.3mol/L, 1.4mol/L, 1.5mol/L, 1.6mol/L, 1.7mol/L, 1.8mol/L, 1.9mol/L, 2.0mol/L, or the like, and the catalyst is not particularly limited. When the molar concentration of the perchloric acid solution is 0.1-2.0 mol/L, the pentavalent neptunium ions can exist stably for a long time in the perchloric acid solution; if the molar concentration of the perchloric acid solution is too high, the pentavalent neptunium ions may undergo disproportionation.
In some embodiments, determining whether the hexavalent neptunium ions contained in the first solution are fully reduced may also be included.
In some of these embodiments, it may be determined that the hexavalent neptunium ions contained in the first solution are completely reduced when the reaction system is a bright green clarified solution that does not contain precipitates.
In some embodiments, the solvent in the solution containing the hexavalent neptunium ions can be removed by heating at 90-140 ℃; for example, the temperature may be 90 ℃, 95 ℃, 100 ℃, 105 ℃, 110 ℃, 115 ℃, 120 ℃, 125 ℃, 130 ℃, 135 ℃, 140 ℃, or the like, and is not particularly limited.
In some embodiments, acetonitrile and pyridine in the reaction system may be removed by draining the solvent with stirring. With the reduction of acetonitrile, the amount of the pentavalent neptunium which can be dissolved in the acetonitrile is reduced, the redundant pentavalent neptunium can be separated out in a solid form, and the pentavalent neptunium solid can be obtained after the acetonitrile and pyridine are pumped out.
In some embodiments, the speed of agitation may be 750-1200r/min; for example, 750r/min, 800r/min, 850r/min, 900r/min, 950r/min, 1000r/min, 1050r/min, 1100r/min, 1150r/min, 1200r/min, etc., are not particularly limited.
The perchloric acid system containing the pentavalent neptunium ions provided in one embodiment is prepared by the method for preparing the perchloric acid system containing the pentavalent neptunium ions.
The perchloric acid system containing pentavalent neptunium ions and the method for preparing the same according to the present invention will be described in detail with reference to the following examples.
The second solution in the following examples is a reaction system obtained by reducing hexavalent neptunium ions in the first solution with pyridine.
Example 1
A10 mL glass bottle was taken and 1mL of a 10mmol/L Np (VI) perchloric acid solution was filled in the bottle. The glass bottle is placed on a heater and heated and evaporated to dryness at 100 ℃ to obtain a first solid containing hexavalent Np.
And dissolving the evaporated first solid containing hexavalent Np by using 1mL of acetonitrile solution to obtain a light pink first solution containing hexavalent Np ions.
Subsequently, 2mL of pyridine solution was added to the first solution, the first solution turned dark brown immediately, and after 3 days of standing, the solution was observed as a bright green clear solution, i.e., as a second solution.
The second solution was transferred to a 50mL round bottom flask, the magneton was added and the solvent (acetonitrile/pyridine) was drained off with stirring at 1000r/min to give a second solid containing pentavalent Np.
The second solid was dissolved with 2mL of 1.0mol/L perchloric acid solution to give a perchloric acid solution containing ions of Np (V) in a monovalent state.
10 mu L of the perchloric acid solution containing Np (V) ions is taken in a liquid flash bottle, 10mL of scintillation liquid is added, and the bottle cap is screwed down and then is shaken in the horizontal direction for 50-100 ℃ so that the perchloric acid solution and the scintillation liquid are fully mixed. Then the liquid flash bottle is put into a liquid flash counter for liquid flash measurement, the alpha count is recorded, and the measurement time is 5min. The final alpha count was 19055.652 and the concentration of the perchloric acid solution was calculated to be 5.1mmol/L.
And (3) taking 50 mu L of the perchloric acid solution containing the Np (V) ions in a cuvette, adding 750 mu L of 1.0mol/L perchloric acid solution, taking 1.0mol/L blank perchloric acid solution as a reference, measuring the absorption spectrum of the perchloric acid solution containing the Np (V) ions in the cuvette, and determining that only the Np (V) ions exist in the solution and no Np ions in other valence states, wherein the spectral range is 355-1400 nm. The absorbance of the absorption peak of Np (V) at 980nm is 0.123, the concentration of Np (V) ions is calculated to be 5.0mmol/L according to the absorbance of the absorption peak of Np (V) at 980nm, and the spectrum measurement result is consistent with the liquid flash measurement result.
The amounts of Np material before and after reduction were calculated to be 0.01mmol, no loss of Np occurred.
Example 2
A10 mL glass bottle was taken and 5mL of a perchloric acid solution containing 20mmol/L Np (VI) was filled in the bottle. The glass bottle was placed on a heater and heated to dryness at 140 ℃ to give a first solid containing hexavalent Np.
And dissolving the evaporated first solid containing hexavalent Np by using 3mL of acetonitrile solution to obtain a light pink first solution containing hexavalent Np ions.
Then 3mL of pyridine solution was added to the first solution, the first solution turned dark brown immediately, after 3 days of standing, dark green insoluble matter was observed at the bottom of the flask, the upper layer was clear green clear solution, the second solution, and the precipitate in the glass flask was filtered out.
The second solution was transferred to a 50mL round bottom flask, the magneton was added and the solvent (acetonitrile/pyridine) was drained off with stirring at 1000r/min to give a second solid containing pentavalent Np.
The second solid was dissolved in 6mL of 1.0mol/L perchloric acid solution to give a perchloric acid solution containing ions of Np (V) in a monovalent state.
10 mu L of the perchloric acid solution containing Np (V) ions is taken in a liquid flash bottle, 10mL of scintillation liquid is added, and the bottle cap is screwed down and then is shaken in the horizontal direction for 50-100 ℃ so that the perchloric acid solution and the scintillation liquid are fully mixed. Then the liquid flash bottle is put into a liquid flash counter for liquid flash measurement, the alpha count is recorded, and the measurement time is 5min. The final alpha count was 39099.403 and the concentration of the perchloric acid solution was calculated to be 10.5mmol/L.
And (3) taking 50 mu L of the perchloric acid solution containing the Np (V) ions in a cuvette, adding 750 mu L of 1.0mol/L perchloric acid solution, taking 1.0mol/L blank perchloric acid solution as a reference, measuring the absorption spectrum of the perchloric acid solution containing the Np (V) ions in the cuvette, and determining that only the Np (V) ions exist in the solution and no Np ions in other valence states, wherein the spectral range is 355-1400 nm. The absorbance of the absorption peak of Np (V) at 980nm is 0.260, the concentration of Np (V) ions is calculated to be 10.5mmol/L according to the absorbance of the absorption peak of Np (V) at 980nm, and the spectrum measurement result is consistent with the liquid flash measurement result.
The dark green insoluble solid was explored and a portion of the solid was taken in a 25mL round bottom flask and 2mL acetonitrile solution was added, the solid did not dissolve significantly. The acetonitrile solution was drained and 2mL of 1.0mol/L perchloric acid solution was added, and the solid was completely dissolved, the solution was yellow-green.
The solution after dissolution was taken in an amount of 5. Mu.L and subjected to liquid flash measurement to give an alpha count of 34300.122, which indicates that the solid contained Np, and the concentration of the Np solution was calculated to be 18.5mmol/L.
And (3) adding 750 mu L of 1.0mol/L perchloric acid solution into a cuvette, taking 1.0mol/L blank perchloric acid solution as a reference, measuring the absorption spectrum of Np (V) solution in the cuvette, wherein the spectral range is 355-1400 nm, and the characteristic absorption peaks at 980nm and 1223nm are observed from the spectrum, which indicates that Np (V) and Np (VI) exist simultaneously, and the concentration ratio of Np (V) to Np (VI) is 3:2. The above results indicate that Np (VI) is not completely reduced and that insolubles are produced when the amount of pyridine added is too small.
After 3-6 mL of pyridine is added into the residual solid, the solid is left for 2-5 days, insoluble matters disappear, and the solution is bright green clear solution. Thus, the generation or absence of precipitation relates to whether or not the reduction of Np (VI) is complete.
The total amount of Np in the solution after reduction and Np in the precipitate was calculated to be 0.1mmol, which was consistent with the amount of Np material before reduction, and no loss of Np occurred.
Example 3
A10 mL glass bottle was taken and 1mL of a 10mmol/L Np (VI) perchloric acid solution was filled in the bottle. The glass bottle is placed on a heater and heated and evaporated to dryness at 90 ℃ to obtain a first solid containing hexavalent Np.
And dissolving the evaporated first solid containing hexavalent Np by using 3mL of acetonitrile solution to obtain a light pink first solution containing hexavalent Np ions.
Subsequently, 3mL of pyridine solution was added to the first solution, the first solution turned dark brown immediately, and after 2 days of standing, the solution was observed as a bright green clear solution, i.e., as a second solution.
The second solution was transferred to a 50mL round bottom flask, magneton was added and the solvent (acetonitrile/pyridine) was drained off with stirring at 750r/min to give a second solid containing pentavalent Np.
The second solid was dissolved with 5mL of a 0.1mol/L perchloric acid solution to give a perchloric acid solution containing ions of Np (V) in a monovalent state.
10 mu L of the perchloric acid solution containing Np (V) ions is taken in a liquid flash bottle, 10mL of scintillation liquid is added, and the bottle cap is screwed down and then is shaken in the horizontal direction for 50-100 ℃ so that the perchloric acid solution and the scintillation liquid are fully mixed. Then the liquid flash bottle is put into a liquid flash counter for liquid flash measurement, the alpha count is recorded, and the measurement time is 5min. The final alpha count was 7600.260 and the concentration of the perchloric acid solution was calculated to be 2.0mmol/L.
Taking 100 mu L of the perchloric acid solution containing Np (V) ions into a cuvette, adding 700 mu L of 1.0mol/L perchloric acid solution, taking 1.0mol/L blank perchloric acid solution as a reference, measuring the absorption spectrum of the perchloric acid solution containing Np (V) ions in the cuvette, determining that only Np (V) ions exist in the solution and no Np ions in other valence states, wherein the spectral range is 355-1400 nm. The absorbance of the absorption peak of Np (V) at 980nm is 0.098, the concentration of Np (V) ions is calculated to be 2.0mmol/L according to the absorbance of the absorption peak of Np (V) at 980nm, and the spectrum measurement result is consistent with the liquid flash measurement result.
The amounts of Np material before and after reduction were calculated to be 0.01mmol, no loss of Np occurred.
Example 4
A10 mL glass bottle was taken and 1mL of a 10mmol/L Np (VI) perchloric acid solution was filled in the bottle. The glass bottle was placed on a heater and heated to dryness at 140 ℃ to give a first solid containing hexavalent Np.
And dissolving the evaporated first solid containing hexavalent Np by using 2mL of acetonitrile solution to obtain a light pink first solution containing hexavalent Np ions.
Subsequently, 1mL of pyridine solution was added to the first solution, the first solution turned dark brown immediately, and after 5 days of standing, the solution was observed as a bright green clear solution, i.e., as a second solution.
The second solution was transferred to a 50mL round bottom flask, magneton was added and the solvent (acetonitrile/pyridine) was drained off with stirring at 1200r/min to give a second solid containing pentavalent Np.
The second solid was dissolved with 4mL of a 2.0mol/L perchloric acid solution to give a perchloric acid solution containing ions of Np (V) in a monovalent state.
10 mu L of the perchloric acid solution containing Np (V) ions is taken in a liquid flash bottle, 10mL of scintillation liquid is added, and the bottle cap is screwed down and then is shaken in the horizontal direction for 50-100 ℃ so that the perchloric acid solution and the scintillation liquid are fully mixed. Then the liquid flash bottle is put into a liquid flash counter for liquid flash measurement, the alpha count is recorded, and the measurement time is 5min. The final alpha count was 9550.826 and the concentration of the perchloric acid solution was calculated to be 2.6mmol/L.
Taking 100 mu L of the perchloric acid solution containing Np (V) ions into a cuvette, adding 700 mu L of 1.0mol/L perchloric acid solution, taking 1.0mol/L blank perchloric acid solution as a reference, measuring the absorption spectrum of the perchloric acid solution containing Np (V) ions in the cuvette, determining that only Np (V) ions exist in the solution and no Np ions in other valence states, wherein the spectral range is 355-1400 nm. The absorbance of the absorption peak of Np (V) at 980nm is 0.125, the concentration of Np (V) ions is calculated to be 2.5mmol/L according to the absorbance of the absorption peak of Np (V) at 980nm, and the spectrum measurement result is consistent with the liquid flash measurement result.
The amounts of Np material before and after reduction were calculated to be 0.01mmol, no loss of Np occurred.
Comparative example 1
Comparative example 1 differs from examples 1 to 4 in that: inorganic sodium nitrite is used as a reducing agent.
Taking 10mL glass bottle, and adding neptunium to the NpO with the content of about 90mg 2 The solid was dissolved in 5mL of concentrated nitric acid with simultaneous addition ofAdding 4-5 drops of concentrated perchloric acid. The flask was placed on a heater and heated to dryness, then dissolved with 5mL of 1.0mol/L nitric acid, the solution was pink, and Np was found to be Np (VI) at this time. To the solution was added 1mL of 2.0mol/L sodium nitrite, and the solution was observed to turn green, indicating that Np (VI) was reduced to Np (V). The Np solution was transferred to a 25mL centrifuge tube, 4.0mol/L sodium hydroxide was added dropwise thereto, a pale green precipitate was formed in the solution, and the solution was gradually added dropwise until the precipitate was no longer increased, and a total of 6mL sodium hydroxide solution was added. And placing the centrifugal tube into a centrifugal machine for centrifugation for 2-3 min, wherein the rotating speed is 3000-3200 rpm. After centrifugation, the bottom of the tube is provided with light-colored solid, and the supernatant is colorless and transparent; transferring the supernatant to a radioactive waste liquid bottle, and transferring the supernatant as clean as possible. Then, 2mL of pure water was added for washing, the mixture was centrifuged for 3min to separate phases, and the supernatant was transferred to a radioactive waste bottle as well, and the above washing operation was repeated three times. The final solid was dissolved in 5mL of 1.0mol/L perchloric acid solution, which was green.
Liquid flash measurement was performed on 5. Mu.L of Np solution, and the final neptunium content was calculated to be approximately 85mg. And then, the Np solution is subjected to absorption spectrum measurement, the spectrum range is 960-1010 nm, np (V) is confirmed, but the baseline in the measurement process is obviously shifted, other impurities possibly exist in the solution, and the purity of Np (V) is poor.
Comparing examples 1 to 4 with comparative example 1, the preparation method in comparative example 1 mainly comprises the following steps: heating and evaporating the nitric acid solution containing Np to obtain Np (VI), adding sodium nitrite to reduce Np (VI) into Np (V), and adding sodium hydroxide to obtain NpO 2 OH precipitation, centrifugation, washing the precipitate with pure water, and continuing centrifugation, dissolving Np (V) solids in the perchloric acid solution.
The preparation method in comparative example 1 has the following problems compared with the preparation method of the present invention: complicated steps, tiny Np loss, radioactive waste liquid generation and poor purity of the final Np solution. According to the perchloric acid system containing pentavalent neptunium ions and the preparation method thereof, provided by the invention, the organic solvent pyridine is used for replacing inorganic salt as a reducing agent to reduce hexavalent neptunium, and the pentavalent neptunium solid can be directly obtained after acetonitrile and pyridine in the reaction system are removed, so that the operation process is simple, and the neptunium is basically completely recovered and no radioactive waste liquid is generated.
The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.
The above examples illustrate only a few embodiments of the invention, which are described in detail and are not to be construed as limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.
Claims (8)
1. A process for the preparation of a perchloric acid system containing pentavalent neptunium ions, comprising:
pyridine is used as a reducing agent, hexavalent neptunium ions are reduced into pentavalent neptunium ions in acetonitrile, and after acetonitrile and pyridine in a reaction system are removed, perchloric acid solution is added to prepare a perchloric acid system containing pentavalent neptunium ions;
the method specifically comprises the following steps:
removing the solvent from the solution containing hexavalent neptunium ions to produce a first solid;
dissolving the first solid by adopting the acetonitrile to prepare a first solution;
adding the pyridine into the first solution to prepare the reaction system;
removing acetonitrile and pyridine in the reaction system to prepare a second solid;
dissolving the second solid in the perchloric acid solution to prepare a perchloric acid system containing pentavalent neptunium ions;
the solution containing the hexavalent neptunium ions is a perchloric acid solution containing the hexavalent neptunium ions.
2. A process for the preparation of a perchloric acid system containing pentavalent neptunium ions according to claim 1, characterized in that the mass ratio of neptunium element contained in said first solution to said pyridine is 1 (400-1300).
3. A process for the preparation of a perchloric acid system containing pentavalent neptunium ions, according to claim 1, characterized in that the molar concentration of the perchloric acid solution used to dissolve the second solid is between 0.1 and 2.0mol/L.
4. A process for preparing a perchloric acid system containing pentavalent neptunium ions, according to claim 1, characterized by further comprising determining whether the hexavalent neptunium ions contained in said first solution are completely reduced.
5. A process for preparing a perchloric acid system containing pentavalent neptunium ions, according to claim 4, characterized in that it is determined that the hexavalent neptunium ions contained in said first solution are completely reduced when said reaction system is a bright green clarified solution containing no precipitate.
6. A process for the preparation of a perchloric acid system containing ions of pentavalent neptunium according to claim 1, characterized in that the solvent of the solution containing ions of hexavalent neptunium is removed by heating at a temperature of between 90 and 140 ℃.
7. Process for the preparation of a perchloric acid system containing pentavalent neptunium ions according to any one of claims 1 to 6, characterized in that acetonitrile and pyridine are removed from the reaction system by draining the solvent with stirring.
8. A process for the preparation of a perchloric acid system containing pentavalent neptunium ions, according to claim 7, characterized in that the stirring speed is 750-1200r/min.
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