Method for determination of neptunium in nitric acid solution
Patent Information
- Application Number
- CN202410034645.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-01-10
- Publication Date
- 2026-10-23
- Estimated Expiration
- 2044-01-10
AI Technical Summary
有机相溶液中，磷酸三丁酯(TBP)萃取Np(IV)和Np(VI)，不萃取Np(V)，因此Np在后处理流程中的走向复杂
Smart Images
Figure CN117949400B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of quantitative analysis technology, and in particular to a method for determining neptunium in nitric acid solution. Background Technology
[0002] Advanced reprocessing procedures require not only the extraction of uranium and plutonium from spent dyes, but also the recovery of actinides and long-lived fission products from high-level radioactive waste. Neptunium (Np) is an important minor actinide element. Np exists in various valence states in the reprocessing feed, specifically Np(IV), Np(V), and Np(VI). Furthermore, different valence states of Np in the aqueous solution can react with high concentrations of NO3. − UO2 2+ Coordination occurs to form complexes, resulting in an abundance of Np species. In the organic phase solution, tributyl phosphate (TBP) extracts Np(IV) and Np(VI), but not Np(V), thus complicating the fate of Np in the post-processing flow.
[0003] However, there is currently a lack of technical means to achieve rapid quantitative analysis of neptunium species and concentration. Summary of the Invention
[0004] Based on this, this application provides a method for determining neptunium in nitric acid solution, so as to achieve rapid quantitative analysis of neptunium species and concentration in the post-processing flow.
[0005] This application provides a method for determining neptunium in nitric acid solution, comprising the following steps:
[0006] Control nitric acid solutions containing different neptunium species were prepared, and the ultraviolet-visible-near-infrared absorption spectra of the control nitric acid solutions were measured.
[0007] The second derivative of the UV-Vis-NIR absorption spectrum of the control nitric acid solution was processed to obtain the second derivative absorption spectrum of the control nitric acid solution.
[0008] Based on the second-order absorption spectrum of the control nitric acid solution, the characteristic peaks of different neptunium species were determined, and a quantitative correction relationship between the peak area of the characteristic absorption peaks of different neptunium species in the second-order absorption spectrum of the control nitric acid solution and the neptunium concentration was established.
[0009] Determine the ultraviolet-visible-near-infrared absorption spectrum of the nitric acid solution to be tested;
[0010] The second derivative of the ultraviolet-visible-near-infrared absorption spectrum of the nitric acid solution to be tested is processed to obtain the second derivative absorption spectrum of the nitric acid solution to be tested.
[0011] The species state of neptunium in the nitric acid solution to be tested is determined based on the characteristic absorption peak in the second-order absorption spectrum of the nitric acid solution to be tested, and the peak area at the characteristic absorption peak in the second-order absorption spectrum of the nitric acid solution to be tested is substituted into the quantitative correction relationship to obtain the neptunium concentration in the nitric acid solution to be tested.
[0012] In some embodiments, the ultraviolet-visible-near-infrared absorption spectra of the control nitric acid solution and the test nitric acid solution are determined by spectrometry.
[0013] In some embodiments, the spectral conditions of the spectral measurement method include:
[0014] The spectral range is 200 nm - 1400 nm, the spectral wavelength interval is 0.1 nm - 1.0 nm, and the scan rate is 60 nm / min - 600 nm / min.
[0015] In some embodiments, the reference for measuring the UV-Vis-NIR absorption spectrum of the control nitric acid solution is any one of air, water, and blank nitric acid solution; and / or
[0016] The reference for measuring the ultraviolet-visible-near-infrared absorption spectrum of the nitric acid solution to be tested is any one of air, water, and blank nitric acid solution.
[0017] In some embodiments, when neptunium is hexavalent, the control nitric acid solution is a series of control nitric acid solutions containing different concentrations of neptunium, wherein the concentration of neptunium in the series of control nitric acid solutions is 1.25 mmol / L-2.5 mmol / L; and / or
[0018] When neptunium is pentavalent, the reference nitric acid solution is a series of reference nitric acid solutions containing different concentrations of neptunium, wherein the concentration of neptunium in the series of reference nitric acid solutions is 0.2 mmol / L-0.5 mmol / L.
[0019] In some embodiments, the second-order absorption spectrum is obtained by taking the second derivative of the absorbance of the ultraviolet-visible-near-infrared absorption spectrum;
[0020] Optionally, the formula used for the second derivative is:
[0021]
[0022] in, λ is the absorbance of the second-order absorption spectrum, A is the absorbance of the ultraviolet-visible-near-infrared absorption spectrum, and λ is the wavelength of the absorption spectrum.
[0023] In some embodiments, when neptunium is hexavalent, the peak position of the characteristic absorption peak in the second-order absorption spectrum is 1225 nm, and the quantitative correction relationship between the peak area of the characteristic absorption peak and the neptunium concentration is: S = 2.98c, R 2 = 0.9999, RSD = 0.34%, where S is the peak area of the characteristic absorption peak and c is the neptunium concentration in mol / L.
[0024] In some embodiments, when neptunium is pentavalent, the peak position of the characteristic absorption peak in the second-order absorption spectrum is 980 nm, and the quantitative correction relationship between the peak area of the characteristic absorption peak and the neptunium concentration is: S = 152.2c, R 2 = 0.9999, RSD = 0.07%, where S is the peak area of the characteristic absorption peak and c is the neptunium concentration in mol / L.
[0025] In some embodiments, when neptunium is tetravalent, the peak position of the characteristic absorption peak in the second-order absorption spectrum is 960 nm, and the quantitative correction relationship between the peak area of the characteristic absorption peak and the neptunium concentration is: S = 88.5c, R 2 = 0.9999, RSD = 0.45%, where S is the peak area of the characteristic absorption peak and c is the neptunium concentration in mol / L.
[0026] In some embodiments, when neptunium is Np(NO3)2 2+ When the complex is used, the peak position of the characteristic absorption peak in the second-order absorption spectrum is 970 nm. The quantitative correction relationship between the peak area of the characteristic absorption peak and the neptunium concentration is: S = 5.14c, RSD = 1.06%, where S is the peak area of the characteristic absorption peak and c is the neptunium concentration in mol / L.
[0027] The method for determining neptunium in nitric acid solution described above first measures the second-order absorption spectra of neptunium under different neptunium species, further determining the characteristic absorption peaks of different neptunium species in the second-order absorption spectra, and the quantitative correction relationship between the peak area of the characteristic absorption peaks of different neptunium species and the neptunium concentration. Then, the second-order absorption spectrum of the nitric acid solution to be tested is measured, and the neptunium species contained in the nitric acid solution to be tested is determined based on the second-order absorption spectrum of the nitric acid solution to be tested. The peak area of the second-order absorption spectrum of the nitric acid solution to be tested at the characteristic absorption peak is substituted into the quantitative correction relationship to obtain the neptunium concentration in the nitric acid solution to be tested. Thus, rapid quantitative analysis of neptunium species and concentration is achieved in the post-processing workflow. Attached Figure Description
[0028] To more clearly illustrate the technical solutions in the embodiments of this application and to more completely understand this application and its beneficial effects, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0029] Figure 1 The second-order conduction absorption spectrum of Np(VI) in Example 1;
[0030] Figure 2 The relationship between the peak area of the characteristic peak in the second-order absorption spectrum of Np(VI) in Example 1 and the concentration of Np(VI);
[0031] Figure 3 The second-order conduction absorption spectrum of Np(V) in Example 1;
[0032] Figure 4 The relationship between the peak area of the characteristic peak in the second-order absorption spectrum of Np(V) in Example 1 and the concentration of Np(V);
[0033] Figure 5 Free Np in Example 1 4+ The second-order absorption spectrum;
[0034] Figure 6 Free Np in Example 1 4+ The peak area of the characteristic peak in the second-order absorption spectrum and the free Np 4+ The relationship between concentration;
[0035] Figure 7 Np in Example 1 4+ and Np(NO3)2 2+ The second-order absorption spectrum. Detailed Implementation
[0036] To facilitate understanding of this application, a more complete description of the application will be provided below with reference to relevant embodiments. Preferred embodiments of the application are given below. However, the application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of this application.
[0037] Unless otherwise defined, 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 application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.
[0038] As used herein, the terms "and / or," "or / and," and "and / or" encompass any one of two or more of the related listed items, as well as any and all combinations of the related listed items. These arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. It should be noted that when at least three items are connected using at least two conjunctions selected from "and / or," "or / and," and "and / or," it should be understood that, in this application, the technical solution undoubtedly includes solutions connected by "logical AND," and also undoubtedly includes solutions connected by "logical OR."
[0039] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.
[0040] In this application, numerical ranges are referred to as continuous unless otherwise specified, and include the minimum and maximum values of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.
[0041] This document only specifically discloses some numerical ranges. However, any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range, just as any upper limit can be combined with any other upper limit to form an unspecified range. Furthermore, each individually disclosed point or single value can itself serve as a lower or upper limit and be combined with any other point or single value or with other lower or upper limits to form an unspecified range.
[0042] Unless otherwise specified, the temperature parameters in this application may be either constant temperature processing or processing within a certain temperature range. The constant temperature processing allows temperature fluctuations within the precision range controlled by the instrument, such as ±5°C, ±4°C, ±3°C, ±2°C, or ±1°C.
[0043] In this document, the term "suitable" as used in phrases such as "suitable combination," "suitable method," and "any suitable method" refers to the ability to implement the technical solution of this application, solve the technical problem of this application, and achieve the expected technical effect of this application.
[0044] In this application, terms such as "further," "even further," and "particularly" are used to describe purposes and indicate differences in content, but should not be construed as limiting the scope of protection of this application.
[0045] In this application, "optionally," "optionally," and "optional" mean that something is optional, that is, it means that it is selected from either "with" or "without." If there are multiple "optional" entries in a technical solution, unless otherwise specified, and there are no contradictions or mutual constraints, each "optional" entry shall be independent.
[0046] In the description of the application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.
[0047] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions. Unless otherwise specified, all technical features and optional technical features of this application can be combined to form new technical solutions.
[0048] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, but sequentially is preferred.
[0049] In related technologies, advanced reprocessing processes require not only the extraction of uranium and plutonium from spent dyes, but also the recovery of actinides and long-lived fission products from high-level radioactive waste liquids. Neptunium (Np) is an important minor actinide element. Np exhibits multiple valence states in the reprocessing feed, existing in three states: Np(IV), Np(V), and Np(VI). Furthermore, different valence states of Np in the aqueous solution can react with high concentrations of NO3. − UO2 2+ Coordination occurs to form complexes, resulting in abundant Np species. In the organic phase solution, tributyl phosphate (TBP) extracts Np(IV) and Np(VI), but not Np(V), thus complicating the fate of Np in the post-processing flow. However, currently, there is a lack of technical means to achieve rapid quantitative analysis of Neptunium species and concentration.
[0050] Based on the above problems, this application first determines the UV-Vis-NIR second-order absorption spectrum of neptunium under different neptunium species, obtains the quantitative correction relationship between the absorption peak area of the characteristic peaks in the second-order absorption spectrum and the concentration, and then obtains the UV-Vis-NIR second-order absorption spectrum of the nitric acid solution to be tested, thereby realizing rapid quantitative analysis of neptunium concentration and species in the post-processing process.
[0051] This application provides a method for determining neptunium in nitric acid solution, comprising the following steps:
[0052] Control nitric acid solutions containing different neptunium species were prepared, and the ultraviolet-visible-near-infrared absorption spectra of the control nitric acid solutions were measured.
[0053] The second derivative of the UV-Vis-NIR absorption spectrum of the control nitric acid solution was processed to obtain the second derivative absorption spectrum of the control nitric acid solution.
[0054] The characteristic peaks of different neptunium species were determined based on the second-order absorption spectrum of the control nitric acid solution, and a quantitative correction relationship between the peak area of the characteristic absorption peaks of different neptunium species in the second-order absorption spectrum of the control nitric acid solution and the neptunium concentration was established.
[0055] Determine the ultraviolet-visible-near-infrared absorption spectrum of the nitric acid solution to be tested;
[0056] The second derivative of the ultraviolet-visible-near-infrared absorption spectrum of the nitric acid solution to be tested was processed to obtain the second derivative absorption spectrum of the nitric acid solution to be tested.
[0057] The species state of neptunium in the nitric acid solution to be tested is determined based on the characteristic absorption peak in the second-order absorption spectrum of the nitric acid solution to be tested. The peak area at the characteristic absorption peak in the second-order absorption spectrum of the nitric acid solution to be tested is then substituted into the quantitative correction relationship to obtain the neptunium concentration in the nitric acid solution to be tested.
[0058] It should be noted that neptunium species state refers to the valence state and the form in which neptunium exists, such as whether it exists as an ionic form or as a complex. For example, neptunium species state includes, but is not limited to, Np(IV), Np(V), Np(VI), and Np(NO3)2. 2+ Complexes, etc. It should be noted that Np(IV) reacts with NO3 in nitric acid solution. − Coordination generates Np(NO3)2 2+ As a complex, Np(IV) exists in two seed states in nitric acid solution: free Np(IV) and the complex Np(NO3)2. 2+ .
[0059] When neptunium is hexavalent, the control nitric acid solution is a series of control nitric acid solutions containing different concentrations of neptunium; when neptunium is pentavalent, the control nitric acid solution is also a series of control nitric acid solutions containing different concentrations of neptunium.
[0060] Understandably, the method for determining neptunium in nitric acid solution provided in this application first measures the second-order absorption spectrum of neptunium under different neptunium species, further determining the characteristic absorption peaks of different neptunium species in the second-order absorption spectrum, and the quantitative correction relationship between the peak area of the characteristic absorption peaks of different neptunium species and the neptunium concentration; then, it measures the second-order absorption spectrum of the nitric acid solution to be tested, determines the neptunium species contained in the nitric acid solution to be tested based on the second-order absorption spectrum of the nitric acid solution to be tested, and substitutes the peak area of the second-order absorption spectrum of the nitric acid solution to be tested at the characteristic absorption peak into the quantitative correction relationship to obtain the neptunium concentration in the nitric acid solution to be tested; thus enabling rapid quantitative analysis of the neptunium species and concentration in the post-processing flow.
[0061] In some embodiments, the ultraviolet-visible-near-infrared absorption spectra of the control nitric acid solution and the test nitric acid solution are determined by spectrometry.
[0062] As one possible implementation method, the spectral conditions for the spectral measurement method include:
[0063] The spectral range is 200 nm - 1400 nm, the spectral wavelength interval is 0.1 nm - 1.0 nm, and the scan rate is 60 nm / min - 600 nm / min.
[0064] As an example, the spectral wavelength interval can be, but is not limited to, 0.1 nm, 0.2 nm, 0.3 nm, 0.4 nm, 0.5 nm, 0.6 nm, 0.7 nm, 0.8 nm, 0.9 nm, 1.0 nm, or any range between any two of the above values. The scan rate can be, but is not limited to, 60 nm / min, 100 nm / min, 150 nm / min, 200 nm / min, 250 nm / min, 300 nm / min, 350 nm / min, 400 nm / min, 450 nm / min, 500 nm / min, 550 nm / min, 600 nm / min, or any range between any two of the above scan rates.
[0065] As one possible implementation method, the reference for measuring the ultraviolet-visible-near-infrared absorption spectrum of the control nitric acid solution is any one of air, water, and blank nitric acid solution.
[0066] In some alternative embodiments, the reference for measuring the ultraviolet-visible-near-infrared absorption spectrum of the nitric acid solution to be tested is any one of air, water, and blank nitric acid solution.
[0067] It should be noted that blank nitric acid solution refers to nitric acid solution that does not contain neptunium.
[0068] In some optional embodiments, when neptunium is hexavalent, the control nitric acid solution is a series of control nitric acid solutions containing different concentrations of neptunium, wherein the concentration of neptunium in the series of control nitric acid solutions is 1.25 mmol / L-2.5 mmol / L; for example, it can be, but is not limited to, 1.25 mmol / L, 1.3 mmol / L, 1.4 mmol / L, 1.43 mmol / L, 1.5 mmol / L, 1.6 mmol / L, 1.67 mmol / L, 1.7 mmol / L, 1.8 mmol / L, 1.9 mmol / L, 2 mmol / L, 2.1 mmol / L, 2.2 mmol / L, 2.3 mmol / L, 2.4 mmol / L, 2.5 mmol / L, or any range between two of the above concentrations.
[0069] In some optional embodiments, when neptunium is pentavalent, the control nitric acid solution is a series of control nitric acid solutions containing different concentrations of neptunium, wherein the concentration of neptunium in the series of control nitric acid solutions is 0.2 mmol / L-0.5 mmol / L; for example, it can be, but is not limited to, 0.2 mmol / L, 0.25 mmol / L, 0.3 mmol / L, 0.35 mmol / L, 0.4 mmol / L, 0.45 mmol / L, 0.5 mmol / L, or any range between two of the above concentrations.
[0070] In some embodiments, the second-order absorption spectrum is obtained by taking the second derivative of the absorbance of the ultraviolet-visible-near-infrared absorption spectrum.
[0071] In some alternative implementations, the formula used for second differentiation is:
[0072]
[0073] in, λ is the absorbance of the second-order absorption spectrum, A is the absorbance of the ultraviolet-visible-near-infrared absorption spectrum, and λ is the wavelength of the absorption spectrum.
[0074] In some implementations, the absorbance of the ultraviolet-visible-near-infrared absorption spectrum is differentiated twice using Origin software to obtain the second-order derivative absorption spectrum.
[0075] In some optional implementations, when neptunium is hexavalent, the peak position of the characteristic absorption peak in the second-order absorption spectrum is 1225 nm, and the quantitative correction relationship between the peak area of the characteristic absorption peak and the neptunium concentration is: S = 2.98c, R 2 = 0.9999, RSD = 0.34%, where S is the peak area of the characteristic absorption peak and c is the neptunium concentration in mol / L.
[0076] As one possible implementation, the characteristic feature is that when neptunium is pentavalent, the peak position of the characteristic absorption peak in the second-order absorption spectrum is 980 nm, and the quantitative correction relationship between the peak area of the characteristic absorption peak and the neptunium concentration is: S = 152.2c, R 2 = 0.9999, RSD = 0.07%, where S is the peak area of the characteristic absorption peak and c is the neptunium concentration in mol / L.
[0077] In some exemplary embodiments, when neptunium is tetravalent, the peak position of the characteristic absorption peak in the second-order absorption spectrum is 960 nm, and the quantitative correction relationship between the peak area of the characteristic absorption peak and the neptunium concentration is: S = 88.5c, R 2 =0.9999, RSD = 0.45%, where S is the peak area of the characteristic absorption peak and c is the neptunium concentration in mol / L.
[0078] In some of these embodiments, neptunium is Np(NO3)2 2+ When the complex is used, the peak position of the characteristic absorption peak in the second-order absorption spectrum is 970 nm. The quantitative correction relationship between the peak area of the characteristic absorption peak and the neptunium concentration is: S = 5.14c, RSD = 1.06%, where S is the peak area of the characteristic absorption peak and c is the neptunium concentration in mol / L.
[0079] The technical solution of the present invention will be described in detail below with reference to specific embodiments. It should be understood that these embodiments are only for illustrating the present invention and are not intended to limit the scope of the present invention. For experimental methods in the following embodiments where specific conditions are not specified, please refer to the guidelines given in this invention, or follow experimental manuals or conventional conditions in the art, or follow the conditions recommended by the manufacturer, or refer to experimental methods known in the art.
[0080] In the specific embodiments described below, the measurement parameters involving raw material components may have slight deviations within the weighing accuracy range unless otherwise specified. Temperature and time parameters are subject to acceptable deviations due to instrument testing accuracy or operational precision.
[0081] Example 1. Establishment of a quantitative relationship between the peak area of the characteristic peak in the second-order conduction absorption spectrum and the Np concentration.
[0082] 1. Establishment of the quantitative relationship between the peak area of the characteristic peak in the second-order conduction absorption spectrum and the Np(VI) concentration.
[0083] Np(VI) nitric acid solutions with concentrations of 2.50 mmol / L, 2.00 mmol / L, 1.67 mmol / L, 1.43 mmol / L, and 1.25 mmol / L were prepared. The Np concentration was measured using a low-background liquid scintillation counter. The ionic strength and acidity of the solutions were 1.0 mol / L, and the temperature was 25 °C. The UV-Vis-NIR absorption spectra of the Np(VI) nitric acid solutions at different concentrations were obtained using a Cary 6000i spectrometer, with wavelengths ranging from 200 to 1400 nm and wavelength intervals of 1.0 nm. Second-order derivative processing of UV-Vis-NIR absorption spectra was performed using Origin software to obtain second-order derivative absorption spectra with different Np(VI) concentrations. Characteristic peaks appeared at 1225 nm for all Np(VI) concentrations, with peak areas of 0.00739, 0.00598, 0.00507, 0.00425, and 0.000374, respectively. Therefore, a quantitative correction relationship was established between the peak area of the characteristic peak and the Np(VI) concentration: S = 2.98c, R... 2 = 0.9999, relative standard deviation RSD = 0.34%.
[0084] The second-order absorption spectrum of Np(VI) is as follows: Figure 1 As shown, the relationship between the peak area of the characteristic peak in the second-order absorption spectrum of Np(VI) and the concentration of Np(VI) is as follows: Figure 2 As shown.
[0085] 2. Establishment of the quantitative relationship between the peak area of the characteristic peak in the second-order conduction absorption spectrum and the Np(V) concentration.
[0086] Np(V) nitric acid solutions with concentrations of 0.5 mmol / L, 0.4 mmol / L, 0.25 mmol / L, and 0.2 mmol / L were prepared. The Np concentration was measured using a low-background liquid scintillation counter. The ionic strength and acidity of the solutions were 1.0 mol / L, and the temperature was 25 °C. The UV-Vis-NIR absorption spectra of the Np(V) nitric acid solutions at different concentrations were obtained using a Cary 6000i spectrometer, with wavelengths ranging from 200 to 1400 nm and wavelength intervals of 1.0 nm. Second-order derivative processing of UV-Vis-NIR absorption spectra was performed using Origin software to obtain second-order derivative absorption spectra with different Np(V) concentrations. Characteristic peaks appeared at 980 nm for all Np(V) concentrations, with peak areas of 0.07603, 0.06097, 0.03810, and 0.03045, respectively. Therefore, a quantitative correction relationship was established between the peak area of the characteristic peak and the Np(V) concentration: S = 152.2c, R... 2 = 0.9999, relative standard deviation RSD = 0.07%.
[0087] The second-order absorption spectrum of Np(V) is as follows: Figure 3 As shown, the relationship between the peak area of the characteristic peak in the second-order absorption spectrum of Np(V) and the concentration of Np(V) is as follows: Figure 4 As shown.
[0088] 3. Establishment of the quantitative relationship between the peak area of the characteristic peak in the second-order conduction absorption spectrum and the Np(IV) concentration.
[0089] Np(IV) reacts with NO3 in nitric acid solution. − Coordination generates Np(NO3)2 2+ As a complex, Np(IV) exists in two seed states in nitric acid solution: free Np. 4+ and its complex Np(NO3)2 2+ Since there is no coordination between Np(IV) and perchlorate, the peak area of the characteristic peak in the second-order absorption spectrum is similar to that of free Np. 4+ The quantitative relationship of concentration will be achieved by measuring different concentrations of Np. 4+ Determined by UV-Vis-NIR absorption spectroscopy in perchloric acid solution. For the complex Np(NO3)2 2+ The peak area of the characteristic peak in the second-order absorption spectrum is related to Np(NO3)2. 2+ The quantitative relationship of concentration will be determined by spectrotitration.
[0090] For free Np 4+Np(IV) perchloric acid solutions with concentrations of 0.5 mmol / L, 0.4 mmol / L, 0.25 mmol / L, and 0.2 mmol / L were prepared. The Np concentration was measured using a low-background liquid scintillation counter. The ionic strength and acidity of the solutions were 1.0 mol / L, and the temperature was 25 ℃. The UV-Vis-NIR absorption spectra of the Np(IV) perchloric acid solutions at different concentrations were obtained using a Cary 6000i spectrometer, with a wavelength range of 200–1400 nm and a wavelength interval of 1.0 nm. Second-order derivative processing of UV-Vis-NIR absorption spectra was performed using Origin software to obtain second-order derivative absorption spectra with different Np(IV) concentrations. Characteristic peaks appeared at 960 nm for all Np(IV) concentrations, with peak areas of 0.04389, 0.03556, 0.02241, and 0.01796, respectively. Therefore, a quantitative correction relationship was established between the peak area of the characteristic peak and the Np(IV) concentration: S = 88.5c, R... 2 = 0.9999, relative standard deviation RSD = 0.45%.
[0091] Among them, free Np 4+ The second-order absorption spectrum is as follows Figure 5 As shown, free Np 4+ The peak area of the characteristic peak in the second-order absorption spectrum and the free Np 4+ The relationship of concentration is as follows Figure 6 As shown.
[0092] For the complex Np(NO3)2 2+ A 0.5 mmol / L Np(IV) perchloric acid solution was prepared. The Np concentration was measured using a low-background liquid scintillation counter. The solution had an ionic strength of 1.0 mol / L, an acidity of 1.0 mol / L, and was prepared at 25 °C. The complex Np(NO3)2 was obtained by spectrotitration using a Cary 6000i spectrometer. 2+ The ultraviolet-visible-near-infrared absorption spectra were obtained, with wavelengths ranging from 200 to 1400 nm and wavelength intervals of 1.0 nm. Using 1.0 mol / L nitric acid solution as the titrant, an appropriate volume was added to the above Np(IV) perchloric acid solution each time. After the solution was thoroughly mixed, the ultraviolet-visible-near-infrared absorption spectra of the solution were collected, resulting in 15-25 ultraviolet-visible-near-infrared absorption spectra. Based on a series of absorption spectral data, Np(NO3)2 was obtained by fitting using Hyperquad software. 2+ The molar UV-Vis-NIR absorption spectrum represents Np(NO3)2 at a Np concentration of 1.0 mol / L.2+ The ultraviolet-visible-near-infrared absorption spectra were obtained. Second-derivative processing of the ultraviolet-visible-near-infrared absorption spectra was performed using Origin software to obtain the Np(NO3)2 concentration at 1.0 mol / L. 2+ The second-order absorption spectrum of the complex Np(NO3)2. 2+ The second-order absorption spectrum shows a characteristic peak at 970 nm, and the peak area of the established characteristic peak is related to Np(NO3)2. 2+ The concentration relationship is S = 5.14c, and the relative standard deviation RSD = 1.06%.
[0093] Among them, Np 4+ and Np(NO3)2 2+ The second-order absorption spectrum is as follows Figure 7 As shown.
[0094] The peak positions of the characteristic peaks of different Np species and the quantitative relationship between the peak area of the characteristic absorption peaks in the second-order absorption spectra and the Np concentration are shown in Table 1.
[0095] Table 1
[0096]
[0097] Example 2. Determination of nitric acid solution containing Np(VI)
[0098] Samples of Np(VI) nitric acid solutions with concentrations of 1.25 mmol / L, 2.00 mmol / L, 2.50 mmol / L, and 3.00 mmol / L were prepared. Np concentration was measured using a low-background liquid scintillation counter. The ionic strength and acidity of the solutions were 1.0 mol / L, and the temperature was 25 °C. The UV-Vis-NIR absorption spectra of the Np(VI) nitric acid solutions at different concentrations were measured, and second-order conduction absorption spectra were obtained. The wavelength range was 200-1400 nm, with a wavelength interval of 1.0 nm. The absorption peak areas at different concentrations were calculated and then substituted into the formula S = 2.98c obtained in Example 1 to calculate the Np concentration. The calculation results for the samples are shown in Table 2.
[0099] Table 2
[0100]
[0101] Example 3. Determination of nitric acid solution containing Np(V)
[0102] Samples of Np(V) nitric acid solutions with concentrations of 0.40 mmol / L, 0.50 mmol / L, 1.00 mmol / L, and 1.50 mmol / L were prepared. The Np concentration was measured using a low-background liquid scintillation counter. The ionic strength and acidity of the solutions were 1.0 mol / L, and the temperature was 25 °C. The UV-Vis-NIR absorption spectra of the Np(V) nitric acid solutions at different concentrations were measured, and second-order conduction absorption spectra were obtained. The wavelength range was 200-1400 nm, with a wavelength interval of 1.0 nm. The absorption peak areas at different concentrations were calculated and then substituted into the formula S = 152.2c obtained in Example 1 to calculate the Np concentration. The calculation results for the samples are shown in Table 3.
[0103] Table 3
[0104]
[0105] Example 4. Determination of nitric acid solution containing Np(IV)
[0106] Samples of Np(IV) nitric acid solutions with concentrations of 0.20 mmol / L, 0.25 mmol / L, 0.40 mmol / L, and 0.50 mmol / L were prepared. The Np concentration was measured using a low-background liquid scintillation counter. The ionic strength and acidity of the solutions were 1.0 mol / L, and the temperature was 25 °C. The UV-Vis-NIR absorption spectra of the Np(IV) nitric acid solutions at different concentrations were measured, and second-order conduction absorption spectra were obtained. The wavelength range was 200-1400 nm, with a wavelength interval of 1.0 nm. The absorption peak areas at different concentrations were calculated and then substituted into the formula S = 88.5c obtained in Example 1 to calculate Np. 4+ The concentration was substituted into the formula S = 5.14c obtained in Example 1 to calculate Np(NO3)2. 2+ The concentration of the complex and the calculated results for the samples are shown in Table 4.
[0107] Table 4
[0108]
[0109] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0110] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.
Claims
1. A method for determining neptunium in nitric acid solution, characterized in that, Includes the following steps: Control nitric acid solutions containing different neptunium species were prepared, and the ultraviolet-visible-near-infrared absorption spectra of the control nitric acid solutions were measured. The second derivative of the UV-Vis-NIR absorption spectrum of the control nitric acid solution was processed to obtain the second derivative absorption spectrum of the control nitric acid solution. Based on the second-order absorption spectrum of the control nitric acid solution, the characteristic peaks of different neptunium species were determined, and a quantitative correction relationship between the peak area of the characteristic absorption peaks of different neptunium species in the second-order absorption spectrum of the control nitric acid solution and the neptunium concentration was established. Determine the ultraviolet-visible-near-infrared absorption spectrum of the nitric acid solution to be tested; The second derivative of the ultraviolet-visible-near-infrared absorption spectrum of the nitric acid solution to be tested is processed to obtain the second derivative absorption spectrum of the nitric acid solution to be tested. The species state of neptunium in the nitric acid solution to be tested is determined based on the characteristic absorption peak in the second-order absorption spectrum of the nitric acid solution to be tested, and the peak area at the characteristic absorption peak in the second-order absorption spectrum of the nitric acid solution to be tested is substituted into the quantitative correction relationship to obtain the neptunium concentration in the nitric acid solution to be tested. The second-order absorption spectrum is obtained by taking the second derivative of the absorbance of the ultraviolet-visible-near-infrared absorption spectrum; The formula used for the second derivative is: ， in, λ is the absorbance of the second-order absorption spectrum, A is the absorbance of the ultraviolet-visible-near-infrared absorption spectrum, and λ is the wavelength of the absorption spectrum. Neptunium species include Np(IV), Np(V), Np(VI), and Np(NO3)2. 2+ Coordination compounds; When neptunium is hexavalent, the characteristic absorption peak in the second-order absorption spectrum is located at 1225 nm. The quantitative correction relationship between the peak area of the characteristic absorption peak and the neptunium concentration is: S = 2.98c, R 2 = 0.9999, RSD = 0.34%, where S is the peak area of the characteristic absorption peak and c is the neptunium concentration in mol / L; When neptunium is pentavalent, the characteristic absorption peak in the second-order absorption spectrum is located at 980 nm. The quantitative correction relationship between the peak area of the characteristic absorption peak and the neptunium concentration is: S = 152.2c, R 2 = 0.9999, RSD = 0.07%, where S is the peak area of the characteristic absorption peak and c is the neptunium concentration in mol / L; When neptunium is tetravalent, the characteristic absorption peak in the second-order absorption spectrum is located at 960 nm. The quantitative correction relationship between the peak area of the characteristic absorption peak and the neptunium concentration is: S = 88.5c, R 2 = 0.9999, RSD = 0.45%, where S is the peak area of the characteristic absorption peak and c is the neptunium concentration in mol / L; When neptunium is Np(NO3)2 2+ When the complex is used, the peak position of the characteristic absorption peak in the second-order absorption spectrum is 970 nm. The quantitative correction relationship between the peak area of the characteristic absorption peak and the neptunium concentration is: S = 5.14c, RSD = 1.06%, where S is the peak area of the characteristic absorption peak and c is the neptunium concentration in mol / L.
2. The determination method as described in claim 1, characterized in that, The ultraviolet-visible-near-infrared absorption spectra of the control nitric acid solution and the test nitric acid solution were determined by spectrometry.
3. The determination method as described in claim 2, characterized in that, The spectral conditions for the spectral measurement method include: The spectral range is 200 nm - 1400 nm, the spectral wavelength interval is 0.1 nm - 1.0 nm, and the scan rate is 60 nm / min - 600 nm / min.
4. The determination method as described in claim 2, characterized in that, The reference for measuring the ultraviolet-visible-near-infrared absorption spectrum of the control nitric acid solution is any one of air, water, and blank nitric acid solution.
5. The determination method as described in claim 2, characterized in that, The reference for measuring the ultraviolet-visible-near-infrared absorption spectrum of the nitric acid solution to be tested is any one of air, water, and blank nitric acid solution.
6. The determination method according to any one of claims 1 to 5, characterized in that, When neptunium is hexavalent, the reference nitric acid solution is a series of reference nitric acid solutions containing different concentrations of neptunium, wherein the concentration of neptunium in the series of reference nitric acid solutions is 1.25 mmol / L-2.5 mmol / L.
7. The determination method according to any one of claims 1 to 5, characterized in that, When neptunium is pentavalent, the reference nitric acid solution is a series of reference nitric acid solutions containing different concentrations of neptunium, wherein the concentration of neptunium in the series of reference nitric acid solutions is 0.2 mmol / L-0.5 mmol / L.
8. The determination method according to any one of claims 1 to 5, characterized in that, The second derivative of the absorbance of the ultraviolet-visible-near-infrared absorption spectrum was obtained by using Origin software.