A method for determining the concentration of tributyl phosphate

Abstract

The invention discloses a method for determining the concentration of tributyl phosphate. The method comprises the following steps: preparing a validation set and a calibration set of samples within a concentration range in a spent fuel reprocessing process, collecting near-infrared absorption spectra of the validation set and the calibration set, establishing a quantitative calibration model, and verifying and obtaining a quantitative model. Near-infrared spectrum detection is performed on a solution in the spent fuel reprocessing process, and the concentration of tributyl phosphate can be obtained simultaneously by performing quantitative model processing on the collected absorption spectra of corresponding wavelengths without pre-processing the solution. The method is simple, improves analysis efficiency, and has high accuracy. The method provides effective data support for online detection of the concentration of tributyl phosphate.

Description

Technical Field

[0001] The invention belongs to the technical field of analytical chemistry, and particularly relates to a method for measuring the concentration of tributyl phosphate. Background Art

[0002] The Purex process is the predominant reprocessing process for spent fuel and is used by all industrial reprocessing plants. Using tributyl phosphate (TBP) as an extractant and an inert hydrocarbon as a diluent, the Purex process selectively extracts uranium and plutonium using TBP to achieve decontamination. Furthermore, based on the significant differences in the extraction properties of Pu ions of different valence states, the process selectively alters the Pu valence through redox reactions to achieve separation between uranium and plutonium.

[0003] The concentration of tributyl phosphate (TBP) directly affects the uranium-plutonium purification coefficient and is a key parameter for process operation, requiring regular measurement. Reprocessing plants use the acid saturation method to measure TBP content in kerosene. This involves extracting nitric acid with a certain volume fraction of TBP / kerosene, then titrating the nitric acid concentration in the organic phase with sodium hydroxide to indirectly calculate the TBP content. Other methods for measuring TBP content include infrared absorption, gas chromatography calibration curves, gas chromatography-mass spectrometry, and the normalization method described in Section 9.2 of GB / T9722-2006. These methods are complex and require high manual effort, making direct online analysis difficult. Summary of the Invention

[0004] In view of the above technical problems existing in the prior art, the object of the present invention is to provide a method for quickly and accurately detecting the concentration of tributyl phosphate in the spent fuel reprocessing process online.

[0005] To achieve the above object of the invention, the technical solution adopted by the present invention is as follows: A method for determining the concentration of tributyl phosphate, comprising the following steps:

[0006] (1) Based on the concentration range of tributyl phosphate in the spent fuel reprocessing process, prepare calibration and validation samples within the concentration range;

[0007] (2) using air as a reference, performing near-infrared spectroscopy on the calibration set and validation set samples, respectively, and collecting the absorption spectra of the samples;

[0008] (3) establishing a quantitative calibration model based on the collected absorption spectra of the calibration set samples, and verifying the quantitative calibration model with the absorption spectra of the validation set samples collected above to obtain a quantitative model;

[0009] (4) Performing near-infrared spectroscopy on the spent fuel reprocessing process solution, and processing the absorption spectrum of the collected corresponding wavelength through the quantitative model to obtain the concentration of tributyl phosphate in the solution.

[0010] The beneficial effects brought about by the technical solution of the present invention are as follows: a method for determining the concentration of tributyl phosphate is provided, wherein a quantitative calibration model is established based on the collected near-infrared absorption spectra of calibration set samples, the quantitative calibration model is calibrated using the near-infrared absorption spectra of validation set samples to obtain a quantitative model, near-infrared spectroscopy detection is performed on a spent fuel reprocessing process solution without pre-processing the solution, and the concentration of tributyl phosphate in the spent fuel reprocessing process solution is obtained by inputting the collected absorption spectra of corresponding wavelengths into the quantitative model for processing; the method of the present invention improves analysis efficiency, has high accuracy, does not require a large number of manual quantitative operations, and provides effective data support for online detection of tributyl phosphate concentration. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a flow chart of a method for determining the concentration of tributyl phosphate according to an embodiment of the present invention;

[0012] Figure 2 1 is a near-near infrared spectra of four different concentrations of tributyl phosphate-kerosene according to an embodiment of the present invention;

[0013] Figure 3 This is a quantitative model for determining the concentration of tributyl phosphate using the method of an embodiment of the present invention. DETAILED DESCRIPTION

[0014] The present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0015] Refer to the attached Figure 1 , an embodiment of the present invention provides a method for measuring the concentration of tributyl phosphate, comprising the following steps:

[0016] (1) Based on the concentration range of tributyl phosphate in the spent fuel reprocessing process, prepare calibration and validation samples within the concentration range;

[0017] (2) using air as a reference, performing near-infrared spectroscopy on the calibration set and validation set samples, respectively, and collecting the absorption spectra of the samples;

[0018] (3) establishing a quantitative calibration model based on the collected absorption spectra of the calibration set samples, and verifying the quantitative calibration model with the absorption spectra of the validation set samples collected above to obtain a quantitative model;

[0019] (4) Spectral detection is performed on the spent fuel reprocessing process solution, and the collected absorption spectrum of the corresponding wavelength is processed by the quantitative model to obtain the concentration of tributyl phosphate in the solution.

[0020] Preferably, in step (1), 39 samples of different concentrations are prepared, including 33 calibration set samples with a TBP volume fraction of 5% to 40%; and 6 validation set samples with the same concentration range as the calibration set, but with completely different specific concentrations from the calibration set samples. The TBP solution is a TBP-kerosene solution.

[0021] Preferably, in step (2), air is used as a reference, the instrument resolution is set to 2.38 nm, the cumulative number of times is 40, and a 1 cm quartz cuvette is used as a measuring cell to collect the absorption spectrum of the above sample.

[0022] Refer to the attached Figure 2 , between the wavelengths of 1800-2100 nm, the spectrum showed an obvious changing trend, including the first harmonic and sum frequency of the stretching vibration of the chemical bonds of hydrogen-containing groups, indicating that the concentration of tributyl phosphate-kerosene can be detected by near-infrared spectroscopy.

[0023] Preferably, in step (3), a quantitative calibration model for determination of tributyl phosphate concentration is established based on the absorption spectra of the calibration set samples combined with partial least squares (PLS).

[0024] The parameters for establishing the quantitative calibration model are shown in Table 1. The root mean square error of cross validation (RMSECV) of the nitric acid calibration model was 0.496, the correlation coefficient r was 0.9989, and the detection range was 5% to 40%.

[0025] Table 1 Quantitative calibration model parameters

[0026] Refer to the attached Figure 3 The quantitative model of the embodiment of the present invention has a good correlation between the prediction result of tributyl phosphate in the sample and the reference value.

[0027] Preferably, in step (4), the concentration of tributyl phosphate in the spent fuel reprocessing process solution is determined using the quantitative model established above, and the results are shown in Table 2.

[0028] Table 2 Sample measurement results

[0029]

[0030] As can be seen from Table 2, the relative deviations of tributyl phosphate concentration predictions using the quantitative models of the present invention are all less than 2.5%. The model-predicted results do not differ significantly from the actual values, demonstrating that the calibration model has high accuracy and can be used for quantitative determination of TBP content in actual processes.

[0031] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A method for measuring the concentration of tributyl phosphate, characterized in that: The following steps are involved: (1) Based on the concentration range of tributyl phosphate in the spent fuel reprocessing process, prepare calibration and validation samples within the concentration range; (2) Using air as a reference, perform near-infrared spectroscopy on the calibration set and validation set samples, respectively, and collect the absorption spectra of the samples. The wavelength range of the near-infrared spectroscopy detection is 1880-1950 nm; (3) establishing a quantitative calibration model based on the collected absorption spectra of the calibration set samples, and verifying the quantitative calibration model with the absorption spectra of the validation set samples collected above to obtain a quantitative model; (4) Spectral detection is performed on the spent fuel reprocessing process solution, and the collected absorption spectrum of the corresponding wavelength is processed by the quantitative model to obtain the concentration of tributyl phosphate in the solution.

2. A method for measuring tributyl phosphate concentration according to claim 1, characterized in that: In step (1), the sample concentrations of the calibration set and the validation set are different.

3. A method for measuring tributyl phosphate concentration according to claim 1, characterized in that: In the step (2), air is used as a reference, the instrument resolution is set to 2.38 nm, a 1 cm quartz cuvette is used as a measurement cell, and the absorption spectra of the calibration set and the validation set samples are collected.

4. A method for measuring tributyl phosphate concentration according to claim 1, characterized in that: In the step (3), a quantitative calibration model for determining tributyl phosphate concentration is established based on the absorption spectra of the calibration set samples combined with the partial least squares method.

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