Method for measuring plutonium content
By reacting and developing color with plutonium ions with azo azo Ⅲ solution and measuring absorbance with an ultraviolet-visible spectrophotometer, the limitations of plutonium valence analysis in the prior art were solved, and efficient and accurate quantitative analysis of plutonium was achieved, which simplified the pretreatment steps and shortened the analysis time.
Patent Information
- Application Number
- CN202510447664.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-10
- Publication Date
- 2025-07-11
AI Technical Summary
The prior art has limitations in determining low concentration plutonium, especially the precision and accuracy of plutonium valence analysis methods, and there are complex pretreatment steps and long measurement times.
Azo Azo III solution is used to react with plutonium ions to develop color, and absorbance is measured using an ultraviolet-visible spectrophotometer, plutonium content is determined through standard curves, pretreatment steps are simplified, and the valence composition and total amount of plutonium are directly measured.
Quantitative analysis of plutonium with high selectivity and strong anti-interference ability is achieved, with detection limit as low as 0.15μg/mL, high analysis efficiency, better than 2.6%, spiking recovery rate is 96%, no complex pretreatment is required, and the analysis time is shortened to 1.5 hours.
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Figure CN120293889A_ABST
Abstract
Description
Technical Field
[0001] This application belongs to the technical field of nuclear fuel cycle, and particularly relates to a method for determining plutonium content. Background Art
[0002] In the process of nuclear fuel cycle technology, the valence composition of plutonium is very complex. In the research and process control of the technological process, plutonium valence analysis and total plutonium determination are required to achieve satisfactory plutonium recovery and purification effects.
[0003] In the process liquid of nuclear fuel cycle technology, plutonium often exists in the form of trivalent or tetravalent, and there is also a small amount of hexavalent plutonium. The commonly used solvent extraction method for plutonium valence analysis is the extraction separation of thenoyltrifluoroacetone (TTA) - α counting measurement method. The pretreatment process takes a long time, and Pu(Ⅲ) may be oxidized during the separation process. Di(2-ethylhexyl) phosphoric acid (D2EHPA) can extract plutonium from low-acid solutions, and triisooctylamine (TiOA) is also used for plutonium valence analysis. However, neither of these two extractants can effectively separate the three plutonium valences. The coulometric method is used to determine Pu(Ⅳ) and Pu(Ⅲ). This method has high precision and accuracy, but its measurement time is long, and it has certain limitations in the determination of low-concentration plutonium. Summary of the Invention
[0004] The purpose of this application is to provide a method for determining plutonium content, which solves the problem of certain limitations in the prior art when determining low-concentration plutonium.
[0005] Technical solutions for achieving the purpose of this application:
[0006] The embodiments of this application provide a method for determining plutonium content, and the method includes:
[0007] Adding arsenazo Ⅲ solution to the sample to be processed, standing for color development to obtain a test fading solution;
[0008] Measuring the absorbance of the test fading solution using an ultraviolet-visible spectrophotometer to obtain a reference absorbance;
[0009] Determining the content of plutonium in the sample to be processed according to the reference absorbance and the pre-obtained standard curve; the standard curve is the proportional relationship between the plutonium ion concentration and the solution absorbance.
[0010] Optionally, the standard curve is obtained through the following steps:
[0011] Obtaining multiple standard solutions with different plutonium ion concentrations, using deionized water as a blank reagent, and adding arsenazo Ⅲ solution to the blank reagent and the multiple standard solutions, standing for color development;
[0012] Using an ultraviolet-visible spectrophotometer, measure the absorbance of the blank reagent and the multiple standard solutions to obtain the comparative absorbance A0 of the blank reagent and the fading absorbance A of each standard solution. x ;
[0013] According to the difference between the fading absorbance A x and the comparative absorbance A0, and using the plutonium ion concentrations of the multiple standard solutions as the abscissa and ordinate, plot the standard curve.
[0014] Optionally, the determining of the plutonium content in the sample to be processed according to the reference absorbance and the pre-obtained standard curve specifically includes:
[0015] Obtain the difference between the reference absorbance and the comparative absorbance A0;
[0016] From the standard curve, determine the plutonium ion concentration corresponding to the difference between the reference absorbance and the comparative absorbance A0 as the plutonium content in the sample to be processed.
[0017] Optionally, the obtaining of the multiple standard solutions with different plutonium ion concentrations specifically includes:
[0018] Transfer 0 mL, 0.5 mL, 1 mL, 1.5 mL, 2 mL, 2.5 mL, 5.0 mL of a preset concentration of Pu(IV) ion standard solution into 25-mL volumetric flasks respectively to obtain multiple standard solutions with plutonium ion concentrations of 0 mg / L, 2 mg / L, 4 mg / L, 6 mg / L, 8 mg / L, 10 mg / L, 20 mg / L.
[0019] Optionally, the measuring of the absorbance of the sample fading solution to be measured using the ultraviolet-visible spectrophotometer specifically includes:
[0020] Measure the absorbance of the sample fading solution to be measured using ultraviolet light with a wavelength of 436 - 536 nm.
[0021] Optionally, the sample to be processed is specifically obtained through the following steps:
[0022] Transfer 1 mL - 2 mL of 1BP solution into a 10-mL volumetric flask, transfer 1 mL - 2 mL of 2BP solution into a 100-mL volumetric flask, and dilute to the corresponding scale with 1 mol / L nitric acid to obtain the diluted 1BP solution and the diluted 2BP solution;
[0023] Respectively transfer 1 mL - 2 mL of the diluted 1BP solution and the diluted 2BP solution into a 25-mL polytetrafluoroethylene crucible, add 1 mL of concentrated nitric acid to each, and evaporate to dryness on an electric furnace at 150°C - 160°C;
[0024] After adding 1 mL to 2 mL of H2SO4 (1+1) and evaporating to dryness, leave it at room temperature.
[0025] Add 3.5 mL to 4 mL of H2SO4 (1+1). After complete dissolution, transfer it to a 25 mL quartz volumetric flask to obtain the sample to be processed.
[0026] Optionally, the sample to be processed is specifically obtained through the following steps:
[0027] Respectively pipette 1 mL of the preset process feed liquid or analysis solution into a 25 mL polytetrafluoroethylene crucible, add 2 to 3 drops of 0.1 mol / L ferrous sulfamate, shake well and let stand for 3 min.
[0028] Add 1 mL to 2 mL of concentrated nitric acid and evaporate to dryness on an electric furnace at 150 °C to 160 °C.
[0029] After adding 1 mL to 2 mL of H2SO4 (1+1) and evaporating to dryness, leave it at room temperature.
[0030] Add 3.5 mL to 4.0 mL of H2SO4 (1+1). After complete dissolution, transfer it to a 25 mL quartz volumetric flask to obtain the sample to be processed.
[0031] Optionally, the content of the arsenazo III solution is 0.05%.
[0032] The beneficial technical effects of this application are as follows:
[0033] A method for determining plutonium content provided by an embodiment of this application includes: adding an arsenazo III solution to the sample to be processed, standing for color development to obtain a sample solution to be measured for fading; measuring the absorbance of the sample solution to be measured for fading using a UV-visible spectrophotometer to obtain a reference absorbance; determining the plutonium content in the sample to be processed according to the reference absorbance and a previously obtained standard curve; the standard curve is the proportional relationship between the plutonium ion concentration and the solution absorbance. This method has strong applicability, high selectivity, can be directly used for quantitative analysis of Pu(IV), has strong anti-interference ability, does not require complex pretreatment steps, the spike recovery rate can reach 96%, the analysis accuracy is high, the precision is better than 2.6%, the pretreatment and measurement process can complete the analysis within 1.5 h, and the analysis efficiency is high. The detection limit of Pu(IV) is 0.15 μg / mL. Compared with traditional spectrophotometers, its detection limit is one order of magnitude lower. This method has been successfully applied in the analysis of plutonium valence states in plutonium process feed liquids and waste liquid recovery processes. Description of the Drawings
[0034] Figure 1 It is a flow diagram of a method for determining plutonium content provided by an embodiment of this application. Detailed Embodiments
[0035] To enable those skilled in the art to better understand this application, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of this application. Obviously, the embodiments described below are only a part of the embodiments of this application, rather than all of them. Based on the embodiments described in this application, all other embodiments obtained by those skilled in the art without creative efforts are within the scope of protection of this application.
[0036] The inventors of this application found in their research that in the determination of plutonium valence state and total plutonium, the detection limit of the commonly used spectrophotometry method is high, but a large number of cations and anions in the solution will interfere with the measurement. The spectrophotometry instrument is easy to obtain and the operation is simple, and it is widely used in glove boxes. Therefore, it is necessary to optimize the original analysis technology, design an analysis method with strong applicability, higher sensitivity and accuracy, facilitate the quality control of process data, and solve the problems existing in the current analysis method.
[0037] For this reason, the embodiments of this application provide a method for determining plutonium content. By virtue of the oxidizing property of tetravalent plutonium ions, arsenazo Ⅲ can be decolorized, and the degree of decolorization is linearly related to the Pu content, thus establishing a new spectrophotometric analysis method for indirectly measuring the total plutonium. Measuring the plutonium valence state by spectrophotometry does not require acid adjustment. By means of the different wavelength values under the characteristic absorption peaks of various valence states of plutonium, the valence state composition of plutonium can be directly determined. Through optimizing the condition test, an analysis method for measuring Pu(Ⅳ) and Pu(Ⅲ) is established, and the total plutonium can be obtained by measuring the content of Pu(Ⅳ). The detection limit of Pu(Ⅳ) in the embodiments of this application is 0.15 μg / mL, which is one order of magnitude lower than that of the traditional spectrophotometer. This method has been successfully applied in the analysis of plutonium valence state in the process feed solution of plutonium and the waste liquid recovery process.
[0038] Based on the above content, in order to clearly and detailedly illustrate the above advantages of this application, the specific implementation manners of this application will be described below in conjunction with the accompanying drawings.
[0039] See Figure 1 , which is a schematic flow chart of a method for determining plutonium content provided by the embodiments of this application.
[0040] A method for determining plutonium content provided by the embodiments of this application includes:
[0041] Step S101: Add arsenazo Ⅲ solution to the sample to be processed, and let it stand for color development to obtain a decolorized solution to be measured;
[0042] Step S102: Measure the absorbance of the decolorized solution to be measured by using an ultraviolet-visible spectrophotometer to obtain a reference absorbance;
[0043] Step S103: Determine the plutonium content in the sample to be processed according to the reference absorbance and the pre-obtained standard curve; the standard curve is the proportional relationship between the plutonium ion concentration and the absorbance of the solution.
[0044] It should be noted that arsenazo III is a rare earth chromogenic reagent. In sulfuric acid medium, the oxidizing property of Pu(IV) ions can fade arsenazo III, and the degree of fading is linearly related to the Pu content. Therefore, the plutonium valence state and the total plutonium amount can be obtained from the absorbance value.
[0045] The embodiments of the present application have strong applicability, high selectivity, can be directly used for the quantitative analysis of Pu(IV), have strong anti-interference ability, do not require complex pretreatment steps, the spike recovery rate can reach 96%, the analysis accuracy is high, the precision is better than 2.6%, the analysis can be completed within 1.5 h in the pretreatment and measurement process, and the analysis efficiency is high. The detection limit of Pu(IV) is 0.15 μg / mL.
[0046] In some possible implementation manners of the embodiments of the present application, the standard curve can be obtained through the following steps:
[0047] Obtain multiple standard solutions with different plutonium ion concentrations, use deionized water as a blank reagent, add arsenazo III solution to the blank reagent and the multiple standard solutions, and let them stand for color development.
[0048] Use a UV-visible spectrophotometer to measure the absorbance of the blank reagent and the multiple standard solutions, and obtain the comparative absorbance A0 of the blank reagent and the fading absorbance A of each standard solution x ;
[0049] According to the difference between the fading absorbance A x and the comparative absorbance A0, and the plutonium ion concentrations of the multiple standard solutions as the horizontal and vertical coordinates, plot the standard curve.
[0050] In one example, the determining the plutonium content in the sample to be processed according to the reference absorbance and the pre-obtained standard curve may specifically include:
[0051] Obtain the difference between the reference absorbance and the comparative absorbance A0;
[0052] Determine the plutonium ion concentration corresponding to the difference between the reference absorbance and the comparative absorbance A0 from the standard curve as the plutonium content in the sample to be processed.
[0053] In another example, the obtaining multiple standard solutions with different plutonium ion concentrations may specifically include:
[0054] Transfer 0 mL, 0.5 mL, 1 mL, 1.5 mL, 2 mL, 2.5 mL, and 5.0 mL of a Pu(IV) ion standard solution with a preset concentration into 25-mL volumetric flasks respectively, to obtain multiple standard solutions with plutonium ion concentrations of 0 mg / L, 2 mg / L, 4 mg / L, 6 mg / L, 8 mg / L, 10 mg / L, and 20 mg / L.
[0055] In some possible implementation manners of the embodiments of the present application, the step of measuring the absorbance of the to-be-determined fading solution by using a UV-visible spectrophotometer may specifically include:
[0056] Measure the absorbance of the to-be-determined fading solution by using ultraviolet light with a wavelength of 436 - 536 nm.
[0057] In one example, the to-be-treated sample is specifically obtained through the following steps:
[0058] Transfer 1 mL - 2 mL of 1BP solution into a 10-mL volumetric flask, and transfer 1 mL - 2 mL of 2BP solution into a 100-mL volumetric flask, and dilute to the corresponding scale with 1 mol / L nitric acid to obtain the diluted 1BP solution and the diluted 2BP solution;
[0059] Respectively transfer 1 mL - 2 mL of the diluted 1BP solution and the diluted 2BP solution into a 25-mL polytetrafluoroethylene crucible, add 1 mL of concentrated nitric acid to each, and evaporate to dryness on an electric furnace at 150°C - 160°C;
[0060] Add 1 mL - 2 mL of H2SO4(1 + 1), evaporate to dryness, and then let it stand at room temperature;
[0061] Add 3.5 mL - 4 mL of H2SO4(1 + 1), wait until it is completely dissolved, and then transfer it to a 25-mL quartz volumetric flask to obtain the to-be-treated sample.
[0062] In another example, the to-be-treated sample is specifically obtained through the following steps:
[0063] Respectively transfer 1 mL of a preset process feed liquid or analysis solution into a 25-mL polytetrafluoroethylene crucible, add 2 - 3 drops of 0.1 mol / L ferrous sulfamate, shake well and let it stand for 3 min;
[0064] Add 1 mL - 2 mL of concentrated nitric acid, and evaporate to dryness on an electric furnace at 150°C - 160°C;
[0065] Add 1 mL - 2 mL of H2SO4(1 + 1), evaporate to dryness, and then let it stand at room temperature;
[0066] Add 3.5 mL to 4.0 mL of H2SO4(1+1). After complete dissolution, transfer it to a 25 mL quartz volumetric flask to obtain the sample to be processed.
[0067] In some possible implementation manners of the embodiments of the present application, the content of the arsenazo Ⅲ solution is 0.05%.
[0068] The following describes in detail a method for determining plutonium content provided by the embodiments of the present application with a specific example.
[0069] A method for determining plutonium content provided by the embodiments of the present application establishes a simple and rapid new spectrophotometric method for directly determining the valence composition of plutonium and obtaining the total amount of plutonium from the valence of plutonium. The specific implementation scheme is as follows:
[0070] The first step is to draw a standard curve
[0071] Transfer 0 mL, 0.5 mL, 1 mL, 1.5 mL, 2 mL, 2.5 mL, and 5.0 mL of 100 mg / L Pu(Ⅳ) ion standard solution into a 25 mL volumetric flask respectively. Add 3.5 mL of H2SO4(1+1) to the volumetric flask, then add 0.8 mL of 0.05% arsenazo Ⅲ solution, and make up the volume to the mark with deionized water and shake well. Let it stand for 30 min for color development. The corresponding standard concentrations C x are 0 mg / L, 2 mg / L, 4 mg / L, 6 mg / L, 8 mg / L, 10 mg / L, and 20 mg / L respectively.
[0072] The second step is standard measurement
[0073] Use a UV-visible spectrophotometer to select an absorption wavelength of 536 nm. Transfer the Pu(Ⅳ) ion standard solution with increasing concentrations from low to high into a 1 cm cuvette respectively, and measure the absorbance A0 of the reagent blank and the absorbance A of the decolorized solution with deionized water as the reference x , and calculate ΔA = A0 - A x . Take ΔA as the ordinate and the concentration C x as the abscissa to draw a standard curve, and the correlation coefficient should be > 0.993.
[0074] The third step is sample preparation
[0075] (1) 1BP and 2BP process liquors
[0076] 1) Transfer 1 mL of 1BP solution to a 10 mL volumetric flask and 1 mL of 2BP solution to a 100 mL volumetric flask, and dilute to the mark with 1 mol / L nitric acid.
[0077] (2) Pipette 1 mL of 1BP and 2BP solutions respectively into a 25 mL polytetrafluoroethylene crucible, add 1 mL of concentrated nitric acid to each, and slowly evaporate to dryness on an electric furnace at 160 °C.
[0078] (3) After adding 1 mL of H2SO4 (1+1) and evaporating to dryness, allow to cool to room temperature.
[0079] (4) Add 3.5 mL of H2SO4 (1+1). After complete dissolution, transfer to a 25 mL quartz volumetric flask. Then add 0.8 mL of 0.05% arsenazo III solution, dilute to the mark with deionized water, mix well, and let stand for 30 min for color development.
[0080] (2) Other valence state aqueous process feed solutions or analytical waste solutions
[0081] (1) Pipette 1 mL of the process feed solution or analytical waste solution respectively into a 25 mL polytetrafluoroethylene crucible, add 2 drops of 0.1 mol / L ferrous sulfamate, shake well and let stand for 3 min. Add 1 mL of concentrated nitric acid, and slowly evaporate to dryness on an electric furnace at 160 °C.
[0082] (2) After adding 1 mL of H2SO4 (1+1) and evaporating to dryness, allow to cool to room temperature.
[0083] (3) Add 3.5 mL of H2SO4 (1+1). After complete dissolution, transfer to a 25 mL quartz volumetric flask. Then add 0.8 mL of 0.05% arsenazo III solution, dilute to the mark with deionized water, mix well, and let stand for 30 min for color development.
[0084] In the fourth step, measure with a UV-visible spectrophotometer. The procedure is the same as in the second step.
[0085] (1) Data processing
[0086] From the measured absorbance values A x and A0 of different plutonium concentrations, calculate ΔA = A0 - A x。
[0087] (2) According to the Pu(IV) standard curve, find the Pu(IV) ion concentration value C x (mg / L) corresponding to ΔA. Obtain the concentration values of plutonium Pu(IV) and the total plutonium.
[0088] The method for determining plutonium content provided by the embodiments of the present application has strong applicability, high selectivity, can be directly used for the quantitative analysis of Pu(IV), has strong anti-interference ability, does not require complex pretreatment steps, the spike recovery rate can reach 96%, the analysis accuracy is high, the precision is better than 2.6%, the analysis can be completed within 1.5 hours during the pretreatment and measurement process, and the analysis efficiency is high. The detection limit of Pu(IV) is 0.15 μg / mL. Compared with the traditional spectrophotometer, its detection line is one order of magnitude lower. This method has been successfully applied in the analysis of plutonium valence states in plutonium process feed solutions and waste liquid recovery processes.
[0089] The above has described the present application in detail in conjunction with the accompanying drawings and embodiments. However, the present application is not limited to the above embodiments. Within the scope of knowledge possessed by those of ordinary skill in the art, various changes can also be made without departing from the purpose of the present application. The content not described in detail in the present application can all adopt the prior art.
Claims
1. A method for determining the plutonium content, characterized in that, The method includes: Adding arsenazo III solution to the sample to be processed, standing still to allow it to develop color, and obtaining a fading solution to be measured; Measuring the absorbance of the fading solution to be measured using a UV-visible spectrophotometer to obtain a reference absorbance; Determining the plutonium content in the sample to be processed according to the reference absorbance and a pre-obtained standard curve; the standard curve is the proportional relationship between the plutonium ion concentration and the absorbance of the solution.
2. The method for determining plutonium content according to claim 1, wherein The standard curve is obtained through the following steps: Obtaining multiple standard solutions with different plutonium ion concentrations, using deionized water as a blank reagent, and adding arsenazo III solution to the blank reagent and the multiple standard solutions, standing still to allow them to develop color; Using an ultraviolet-visible spectrophotometer, measure the absorbances of the blank reagent and the multiple standard solutions to obtain the comparative absorbance A0 of the blank reagent and the fading absorbance A of each standard solution x ; According to the difference between the fading absorbance A x and the reference absorbance A0, and the plutonium ion concentrations of the plurality of standard solutions as the horizontal and vertical coordinates, the standard curve is plotted.
3. The method for determining plutonium content according to claim 2, wherein The step of determining the plutonium content in the sample to be processed according to the reference absorbance and a pre-obtained standard curve specifically includes: Obtaining the difference between the reference absorbance and the comparative absorbance A0; Determining, from the standard curve, the plutonium ion concentration corresponding to the difference between the reference absorbance and the comparative absorbance A0 as the plutonium content in the sample to be processed.
4. The method for determining plutonium content according to claim 2, characterized in that, The step of obtaining multiple standard solutions with different plutonium ion concentrations specifically includes: Transferring 0 mL, 0.5 mL, 1 mL, 1.5 mL, 2 mL, 2.5 mL, 5.0 mL of a Pu(IV) ion standard solution with a preset concentration into 25 mL volumetric flasks respectively, to obtain multiple standard solutions with plutonium ion concentrations of 0 mg / L, 2 mg / L, 4 mg / L, 6 mg / L, 8 mg / L, 10 mg / L, 20 mg / L.
5. The method for determining plutonium content according to any one of claims 1-4, characterized in that, The step of measuring the absorbance of the fading solution to be measured using a UV-visible spectrophotometer specifically includes: Measuring the absorbance of the fading solution to be measured using ultraviolet light with a wavelength of 436 - 536 nm.
6. The method for determining plutonium content according to any one of claims 1-4, characterized in that, The sample to be processed is specifically obtained through the following steps: Transferring 1 mL - 2 mL of 1BP solution into a 10 mL volumetric flask, transferring 1 mL - 2 mL of 2BP solution into a 100 mL volumetric flask, and diluting to the corresponding scale with 1 mol / L nitric acid to obtain a diluted 1BP solution and a diluted 2BP solution; Respectively transferring 1 mL - 2 mL of the diluted 1BP solution and the diluted 2BP solution into a 25 mL polytetrafluoroethylene crucible, adding 1 mL of concentrated nitric acid to each, and evaporating to dryness on an electric furnace at 150°C - 160°C; Adding 1 mL - 2 mL of H2SO4(1+1), evaporating to dryness, and then placing at room temperature; Adding 3.5 mL - 4 mL of H2SO4(1+1), waiting for complete dissolution, and then transferring to a 25 mL quartz volumetric flask to obtain the sample to be processed.
7. The method for determining plutonium content according to any one of claims 1-4, characterized in that, The sample to be processed is specifically obtained through the following steps: Respectively transferring 1 mL of a preset process feed solution or analytical solution into a 25 mL polytetrafluoroethylene crucible, adding 2 - 3 drops of 0.1 mol / L ferrous sulfamate, shaking well and standing for 3 min; Adding 1 mL - 2 mL of concentrated nitric acid, and evaporating to dryness on an electric furnace at 150°C - 160°C; Adding 1 mL - 2 mL of H2SO4(1+1), evaporating to dryness, and then placing at room temperature; Add 3.5 mL to 4.0 mL of H2SO4 (1+1). After complete dissolution, transfer it to a 25-mL quartz volumetric flask to obtain the sample to be treated.
8. The method for determining plutonium content according to any one of claims 1 to 4, characterized in that, The content of the arsenazo III solution is 0.05%.