A method for detecting strontium-90 in a solution

Abstract

This invention relates to a method for detecting strontium-90 in solution, belonging to the field of radionuclide detection technology. The invention utilizes cadmium salts and crown ether carboxylic acid ligands to prepare a porous scintillator that possesses both strontium-90 adsorption and enrichment properties and scintillation luminescence properties; the crown ether carboxylic acid ligands have an 18-crown ether-6 functional group, which is effective for Sr... 2+ It possesses strong chemical affinity and can selectively adsorb and enrich strontium ions in solution through coordination. It also utilizes the β-rays released by the decay of strontium-90 to induce a scintillation signal. By collecting this scintillation signal, quantitative detection of strontium-90 nuclide can be achieved. Furthermore, a portable detection device is assembled using this porous scintillator as the core, along with devices such as photomultiplier tubes and digital multichannel pulse analyzers. This device greatly simplifies the detection process, improves detection efficiency and response speed, and has good field adaptability.

Description

Technical Field

[0001] This invention belongs to the field of radionuclide detection technology, and particularly relates to a method for detecting strontium-90 in solution. Background Technology

[0002] Strontium-90 is a radioactive nuclide produced by nuclear fission, characterized by its long half-life, high environmental mobility, and high biotoxicity. Due to the high chemical similarity between strontium ions and calcium ions, strontium-90, once introduced into the natural environment and organisms, can migrate and accumulate through water, soil, and the food chain, particularly readily depositing in skeletal tissues, posing a long-term potential threat to ecological safety and human health. Therefore, achieving rapid, sensitive, and accurate detection of strontium-90 in aquatic environments is of great significance in various nuclear safety scenarios, including routine operation and maintenance of nuclear power plants, spent fuel reprocessing, radioactive waste management, nuclear accident emergency response, and routine environmental radioactivity monitoring.

[0003] Currently, the detection technologies for strontium-90 in solution are mainly divided into three categories: radioactive nuclear detection, mass spectrometry, and optical / chemical sensing detection. However, each of these existing technologies has inherent technical defects and is difficult to adapt to the actual application scenarios of rapid on-site detection.

[0004] Traditional radioactive nuclide detection methods rely on liquid scintillation counting, low-background beta counting, and complementary radiochemical analysis techniques. Since strontium-90 is a pure beta radionuclide, it cannot be directly and accurately quantified using conventional energy dispersive spectroscopy instruments. Complex processes such as precipitation, extraction, ion exchange, and chromatographic separation are necessary to enrich, separate, and purify strontium-90 in the sample before counting and quantitative analysis can be performed. While these methods offer high sensitivity and accuracy, the sample pretreatment steps are cumbersome, the detection cycle is long, and they are highly dependent on specialized laboratory environments and operator experience. They can only achieve offline laboratory detection and cannot meet the needs of rapid in-situ detection, rapid emergency response to nuclear accidents, and continuous dynamic monitoring. Furthermore, the abundant coexistence of calcium, magnesium, sodium, and potassium ions in the aquatic environment further interferes with the separation and purification of strontium-90, reducing detection accuracy.

[0005] Mass spectrometry is a crucial technique for the accurate detection of Strontium-90, commonly including inductively coupled plasma mass spectrometry (ICP-MS) and thermal ionization mass spectrometry (TIMS). While these techniques offer excellent mass resolution, enabling precise determination of low-content Strontium-90, significant interference from matrix ions and isotopes like zirconium-90 in environmental samples necessitates complex sample separation and purification pretreatment to ensure accuracy. Furthermore, mass spectrometry equipment is expensive, bulky, and requires stringent operation and maintenance conditions, exhibiting poor portability and field adaptability, making it unsuitable for in-situ field detection and emergency monitoring.

[0006] In recent years, optical / chemical sensing technologies based on detection principles such as fluorescence quenching, fluorescence enhancement, and colorimetric color change have gradually gained industry attention due to their advantages of simple operation, fast response speed, and high visualization. These technologies achieve specific adsorption and complexation responses of strontium ions through functional recognition groups or sensing materials, effectively simplifying the detection process. However, because strontium-90 and stable strontium isotopes have almost identical chemical properties, existing optical / chemical sensing technologies can only identify and detect total strontium ions, failing to distinguish between radioactive strontium-90 and stable strontium isotopes in a sample. This results in severely insufficient specificity for nuclide detection, making it difficult to achieve targeted and accurate detection of strontium-90 nuclides in solution.

[0007] Therefore, there is an urgent need to develop a detection method that combines the specific enrichment capacity of strontium-90 with precise radiation response performance, so as to achieve rapid capture and real-time accurate detection of strontium-90 in complex aquatic environments. Summary of the Invention

[0008] Therefore, the technical problem to be solved by the present invention is to overcome the problems of existing strontium-90 detection technology in solution, such as cumbersome sample pretreatment, long detection time, reliance on large equipment, inability to detect on-site, and difficulty in distinguishing between radioactive strontium-90 and stable strontium isotopes.

[0009] To address the aforementioned technical problems, this invention provides a method for detecting Strontium-90 in solution. A porous scintillator, possessing both Strontium-90 adsorption and enrichment properties and scintillation luminescence properties, is prepared using cadmium salts and crown ether carboxylic acid ligands. The crown ether carboxylic acid ligands contain an 18-crown ether-6 functional group, which enhances the adsorption and enrichment of Strontium-90 by Sr. 2+ It possesses strong chemical affinity, enabling selective adsorption and enrichment of strontium ions in solution through coordination. Furthermore, it utilizes the β-rays released during the decay of strontium-90 to induce a scintillation signal, allowing for quantitative detection of strontium-90 nuclides. A portable detection device is further assembled using this porous scintillator as the core, combined with a photomultiplier tube, a digital multichannel pulse analyzer, and other components. This device significantly simplifies the detection process, improves detection efficiency and response speed, and possesses excellent field adaptability, providing an efficient and feasible technical means for monitoring radioactive waste, analyzing environmental water samples, and responding to nuclear accidents.

[0010] The purpose of this invention is to provide a method for detecting strontium-90 in solution, comprising the following steps: S1, cadmium salt and crown ether carboxylic acid ligands are reacted in a solvent to obtain a porous scintillator; S2. Assemble the porous scintillator, miniature power supply, peristaltic pump, photomultiplier tube, and digital multichannel pulse analyzer described in S1 to obtain a portable detection device; the peristaltic pump and the digital multichannel pulse analyzer are electrically connected to the miniature power supply; the photosensitive surface of the photomultiplier tube is aligned with the porous scintillator, and its signal output terminal is connected to the digital multichannel pulse analyzer; the communication interface of the digital multichannel pulse analyzer is externally connected to a data analysis unit; S3. Start the portable detection device described in S2. First, pass pure water to collect the background signal, then pass an aqueous solution containing strontium-90 through the porous scintillator. Strontium ions are adsorbed and enriched. The β-rays released by the decay of strontium-90 excite the porous scintillator to generate a scintillation light signal. The photomultiplier tube collects the scintillation light signal and converts it into an electrical pulse signal. The electrical pulse signal is input into a digital multichannel pulse analyzer for signal analysis. Photon counting signals at different times are collected to complete the detection of strontium-90 in the solution.

[0011] In one embodiment of the present invention, in S1, the cadmium salt is selected from cadmium nitrate and / or cadmium chloride.

[0012] In one embodiment of the present invention, in S1, the crown ether carboxylic acid ligand is tetrakis(4-carboxyphenyl)-dibenzo-18-crown-6.

[0013] In one embodiment of the present invention, in S1, the solvent is selected from N,N-dimethylformamide and / or N,N-diethylformamide.

[0014] In one embodiment of the present invention, in S1, the molar ratio of the cadmium salt to the crown ether carboxylic acid ligand is (4.8-5.2):1.

[0015] In one embodiment of the present invention, in S1, the reaction temperature is 75°C-85°C and the time is 44h-52h.

[0016] In one embodiment of the present invention, in S2, the portable detection device further includes a fluid conduit that connects the inlet to the outlet via a porous scintillator.

[0017] In one embodiment of the present invention, in S2, the data analysis unit is a computer.

[0018] In one embodiment of the present invention, in S2, the porous scintillator and the photomultiplier tube are subjected to light-shielding treatment.

[0019] In one embodiment of the present invention, in S3, the amount of pure water introduced is 45mL-55mL.

[0020] The technical solution of the present invention has the following advantages compared with the prior art: (1) The detection method of the present invention uses cadmium salt and crown ether carboxylic acid ligands as raw materials and synthesizes a porous scintillator with selective adsorption and scintillation emission capabilities by solvothermal method. The porous scintillator can directly and selectively adsorb and enrich strontium ions in the solution system. The β-rays released by the decay of strontium-90 are used to excite the material to generate scintillation signals, realizing the integration of strontium-90 enrichment and detection signal conversion. Using this porous scintillator as the core detection unit, a portable detection device is built with photomultiplier tubes, digital multichannel pulse analyzers and data analysis units to realize the integrated operation of sample transportation, nuclide enrichment, scintillation signal acquisition and result analysis. It can complete the in-situ rapid detection of strontium-90, shorten the detection time, get rid of the dependence on large laboratory detection equipment, simplify the detection process and improve the response speed.

[0021] (2) The detection signal of the detection method described in this invention is derived from the scintillation emission induced by β-rays generated by the intrinsic radioactive decay of Strontium-90, rather than relying solely on the chemical color development, fluorescence enhancement or fluorescence quenching response of Strontium ions. This can effectively reduce the interference of stable Strontium isotopes on the detection results and improve the targeting of radioactive Strontium-90 detection. It can be applied to scenarios such as environmental water sample monitoring, radioactive waste liquid screening and nuclear accident emergency detection. Attached Figure Description

[0022] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein: Figure 1 This is a schematic diagram of the portable detection device of the present invention; Figure 2 The results show the adsorption performance of the porous scintillator of the present invention for strontium ions; where a is the adsorption kinetic curve and b is the adsorption isotherm and the Langmuir model fitting curve. Figure 3 The fluorescence and radiation scintillation luminescence properties of the porous scintillator of the present invention are shown; wherein, a is the absorption-emission spectrum and X-ray excitation emission spectrum of the porous scintillator, and b is the self-luminescence image of the porous scintillator before and after adsorption of strontium-90 ions; Figure 4 The linear fitting curve of photon count-activity concentration for Strontium-90 by the porous scintillator of this invention; Figure 5 The results are shown in the portable detection device of the present invention for in-situ detection of strontium-90 in solution. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0024] In this invention, unless otherwise stated, the CAS number of tetra(4-carboxyphenyl)-dibenzo-18-crown-6 used in the examples is 1620959-59-2.

[0025] Example 1 The method for detecting strontium-90 in solution in this embodiment specifically includes the following steps: S1. Preparation of porous scintillator: Cadmium nitrate and tetra(4-carboxyphenyl)-dibenzo-18-crown-6 were added to 2 mL of N,N-dimethylformamide at a molar ratio of 5:1. The mixture was then transferred to a glass scintillator bottle and placed in an 80℃ oven for constant temperature reaction for 48 h to obtain a porous scintillator. S2. Assembly of the portable detection device: Refer to... Figure 1 As shown, a portable chassis with a handle is selected, with overall dimensions of 30cm×30cm×30cm. The chassis houses a miniature power supply, a peristaltic pump, a porous scintillator, a photomultiplier tube (PMT), and a digital multichannel pulse analyzer (MCA). The miniature power supply is fixed on the upper layer of the chassis, and the peristaltic pump is installed on the lower layer of the chassis, connected to a fluid pipeline. One end of the pipeline is the sample inlet, which is connected to the detection chamber containing the porous scintillator. The other end of the pipeline leads out of the chassis as the sample outlet. The peristaltic pump power cable is connected to the miniature power supply. The porous scintillator is placed in the detection chamber. The PMT is installed on the upper part of the detection chamber with its photosensitive surface aligned with the porous scintillator. The MCA is fixed on the upper layer of the chassis, and the PMT signal output terminal is connected to the MCA. The MCA power cable is connected to the miniature power supply. During assembly, the detection chamber and PMT are protected from light. The MCA's data communication interface is led out of the chassis and connected to a computer serving as the data analysis unit. S3. Detection of Strontium-90 in solution: Start the portable detection device and first pump 50 mL of pure water in using a peristaltic pump, simultaneously collecting and outputting the detection signal as a background signal; then pump the Strontium-90-containing aqueous solution into the detection chamber through the inlet, and after fully contacting the porous scintillator, it flows out through the outlet. Strontium ions in the solution are rapidly adsorbed and enriched by the porous scintillator. The β-rays released by the decay of Strontium-90 excite the porous scintillator to generate a scintillation light signal. The light signal is collected by the PMT and converted into an electrical pulse signal. The electrical pulse signal is input into the MCA and the signal is analyzed. The photon count signal at different times is recorded, thereby realizing the detection of Strontium-90 in solution.

[0026] Test Example 1 The strontium ion adsorption performance of the porous scintillator in Example 1 was tested by adsorption kinetics and isothermal adsorption tests. In the kinetic test, 20 mg of the porous scintillator was placed in 20 mL of a 20 mg / L strontium ion aqueous solution and stirred at a constant temperature. Samples were taken at different time points within 60 min after stirring began. After solid-liquid separation, the strontium ion concentration C in the supernatant at time t was detected using inductively coupled plasma optical emission spectrometry (ICP-OES). t The strontium ion removal rate R was calculated. In the isothermal adsorption test, multiple strontium ion solutions with different initial strontium ion concentrations C0 were prepared, and the same mass of porous scintillator was added. The solutions were stirred at a constant temperature until adsorption equilibrium was reached. After solid-liquid separation, the equilibrium strontium ion concentration C was measured. e Calculate the equilibrium adsorption capacity q e The adsorption data were fitted using the Langmuir model, and the results are as follows: Figure 2 As shown. From Figure 2 It can be seen that the porous scintillator has a rapid adsorption capacity for strontium ions, reaching adsorption equilibrium within 2 minutes, proving that the porous scintillator can achieve rapid enrichment of strontium ions; the coefficient of determination R of the adsorption isotherm after fitting with the Langmuir model is... 2 The value was 0.99, and the saturated adsorption capacity of the porous scintillator for strontium ions was found to be 39.86 mg / g. This indicates that the porous scintillator has a considerable adsorption capacity for strontium ions and can effectively capture and enrich strontium ions in the solution system.

[0027] Test Example 2 The crystal structure of the porous scintillator in Example 1 was characterized using X-ray single-crystal diffraction. The ultraviolet excitation emission spectrum and fluorescence quantum yield of the porous scintillator were obtained using a steady-state transient fluorescence spectrometer (FS980). The radioactive emission spectrum of the porous scintillator under X-ray excitation was acquired using a fiber optic spectrometer. Simultaneously, the adsorption of strontium by the porous scintillator was investigated. Experiments on the acquisition of β-ray induced spontaneous emission signals around 90°C, first collecting signals without strontium... The self-luminescence signal of the porous scintillator treated with 90% adsorption was used as the background signal before adsorption, and then strontium-containing... A 90% aqueous solution was used to immerse the porous scintillator in the solution to complete the strontium extraction process. After 90% adsorption, the porous scintillator was removed and the self-luminescence signal was collected again. The adsorbed strontium was compared with that of the strontium. Changes in self-luminous signal before and after 90°C are used to evaluate the strontium-induced emission of porous scintillators. The material exhibits 90% β-ray induced autoluminescence. Tests were conducted on three types of properties: ultraviolet-excited fluorescence, X-ray-excited scintillation luminescence, and β-ray induced autoluminescence. The results are as follows: Figure 3 As shown. From Figure 3It can be seen that the porous scintillator can produce blue fluorescence upon ultraviolet light excitation, with a fluorescence quantum yield of up to 71.47%. Under X-ray excitation, an emission spectrum matching the fluorescence emission characteristics is obtained, confirming the material's excellent scintillatory luminescence performance. Compared to before Strontium-90 adsorption, the porous scintillator after Strontium-90 adsorption can collect a significant β-ray induced autoluminescence signal, indicating that the porous scintillator can effectively convert the β-ray energy released by Strontium-90 decay into a visible light signal. These results demonstrate that the porous scintillator possesses both Strontium ion adsorption and enrichment capabilities and radiation-induced scintillatory luminescence capabilities, enabling rapid enrichment and detection of Strontium-90 in water.

[0028] Test Example 3 5 mg of porous scintillator was weighed and placed in 5 mL of strontium-90 aqueous solutions with different initial activity concentrations. The mixture was stirred for 4 h to allow adsorption equilibrium to be reached. The adsorbed solutions were then separated by filtration. The concentration of strontium-90 in the liquid phase was measured using a liquid scintillator counter to complete the adsorption and enrichment of strontium-90. After enrichment, photon signal acquisition was performed on the porous scintillator after strontium ion adsorption, and a linear correlation was established between photon count intensity and strontium-90 activity concentration. The results are as follows: Figure 4 As shown. From Figure 4 It can be seen that the photon count collected after the porous scintillator adsorbs strontium ions increases with the increase of strontium-90 activity concentration, and the coefficient of determination R of the linear relationship between the photon count and the strontium-90 activity concentration is [missing information]. 2 =0.9998, indicating excellent linear correlation. Based on this linear relationship, the limit of detection (LOD) for strontium-90 calculated by this method is 134.7 Bq / L (2.9 × 10⁻⁶). - (¹³mol / L), demonstrating that this detection method can achieve sensitive quantitative detection of trace strontium-90 in water.

[0029] Test Example 4 Based on Example 1, a porous scintillator was used to enrich and detect strontium-90-containing aqueous solutions, and the results are as follows. Figure 5 As shown. From Figure 5 It can be seen that the detection device maintains a stable background signal level before injecting the Strontium-90 aqueous solution. After the Strontium-90 aqueous solution is injected, the photon counting signal rises rapidly. The device can complete the enrichment and detection process of Strontium-90 within 15 minutes. After the signal rises, it tends to stabilize, which can realize in-situ continuous signal acquisition of Strontium-90 in solution.

[0030] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for detecting strontium-90 in solution, characterized in that, Includes the following steps: S1, cadmium salt and crown ether carboxylic acid ligands are reacted in a solvent to obtain a porous scintillator; S2. Assemble the porous scintillator, miniature power supply, peristaltic pump, photomultiplier tube, and digital multichannel pulse analyzer described in S1 to obtain a portable detection device; the peristaltic pump and the digital multichannel pulse analyzer are electrically connected to the miniature power supply; the photosensitive surface of the photomultiplier tube is aligned with the porous scintillator, and the signal output terminal is connected to the digital multichannel pulse analyzer. The digital multichannel pulse analyzer has an external data analysis unit connected to its communication interface. S3. Start the portable detection device described in S2. First, pass pure water to collect the background signal, then pass an aqueous solution containing strontium-90 through the porous scintillator. Strontium ions are adsorbed and enriched. The β-rays released by the decay of strontium-90 excite the porous scintillator to generate a scintillation light signal. The photomultiplier tube collects the scintillation light signal and converts it into an electrical pulse signal. The electrical pulse signal is input into a digital multichannel pulse analyzer for signal analysis. Photon counting signals at different times are collected to complete the detection of strontium-90 in the solution.

2. The method for detecting strontium-90 in solution according to claim 1, characterized in that, In S1, the cadmium salt is selected from cadmium nitrate and / or cadmium chloride.

3. The method for detecting strontium-90 in solution according to claim 1, characterized in that, In S1, the crown ether carboxylic acid ligand is tetra(4-carboxyphenyl)-dibenzo-18-crown-6.

4. The method for detecting strontium-90 in solution according to claim 1, characterized in that, In S1, the solvent is selected from N,N-dimethylformamide and / or N,N-diethylformamide.

5. The method for detecting strontium-90 in solution according to claim 1, characterized in that, In S1, the molar ratio of the cadmium salt to the crown ether carboxylic acid ligand is (4.8-5.2):

1.

6. The method for detecting strontium-90 in solution according to claim 1, characterized in that, In S1, the reaction temperature is 75℃-85℃ and the time is 44h-52h.

7. The method for detecting strontium-90 in solution according to claim 1, characterized in that, In S2, the portable detection device also includes a fluid conduit that connects the inlet to the outlet via a porous scintillator.

8. The method for detecting strontium-90 in solution according to claim 1, characterized in that, In S2, the data analysis unit is a computer.

9. The method for detecting strontium-90 in solution according to claim 1, characterized in that, In S2, the porous scintillator and the photomultiplier tube are protected from light.

10. The method for detecting strontium-90 in solution according to claim 1, characterized in that, In S3, the amount of pure water introduced is 45 mL to 55 mL.

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