A high-sensitivity on-site uranium content determination instrument based on multiple light sources

Abstract

The present invention belongs to the technical field of uranium content detection, and specifically relates to a high-sensitivity uranium content on-site measuring instrument based on multiple light sources. The device is based on the characteristic fluorescence principle of uranyl ion-fluorescence enhancer complex, uses multiple UV-LEDs as light sources, miniaturized photomultiplier tubes or silicon photomultipliers as photoelectric conversion elements, and uses fluorescent cuvettes as measuring cells. The light intensity of the excitation light source is improved, the detection limit can be reduced by several times, and the technical difficulty of the sensitivity of the on-site uranium measuring instrument is solved, while the volume and power consumption of the equipment are greatly reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of uranium content detection, and in particular relates to a high-sensitivity on-site uranium content measuring instrument based on multiple light sources. Background Art

[0002] With the rapid development of nuclear power and military industry, the demand for natural uranium in various countries around the world has also begun to rise sharply, forming a large uranium mine development boom. However, the problem that comes with it is that the number and types of radioactive wastewater generated in uranium mining and uranium hydrometallurgy are increasing. The radioactive wastewater from uranium mining and uranium hydrometallurgy in my country has the characteristics of low concentration, large quantity, and wide pollution area. These wastewaters contain natural radioactive elements with long half-lives such as uranium, thorium and radium. If they are discharged directly without treatment, they will not only pollute surface water, but also slowly seep into the ground, causing groundwater pollution, and then expand to the entire biosphere, and ultimately cause chemical toxicity and radiation hazards to humans and animals. Therefore, the detection of uranium and other radioactive nuclides in various environmental water bodies is very important, which is related to the national ecological and environmental safety and people's health. Among them, in addition to the confirmation of laboratory instrument methods, the detection of uranium in environmental water bodies also requires on-site detection methods and tools. The data from on-site detection can quickly reflect the quality of environmental water bodies, provide effective data for government supervision, environmental governance, and enterprise pollution discharge, and also provide key data for the judgment of emergencies and the proposal of emergency measures.

[0003] At present, the technologies for detecting uranium in environmental water bodies include laser fluorescence, spectrophotometry, inductively coupled plasma photometry, inductively coupled plasma mass spectrometry (ICP-MS), etc. Among them, spectrophotometry requires multiple steps of sample pretreatment, including extraction, back extraction, masking, color development, etc. The operation is relatively complicated. Although it is widely used, the detection sensitivity is not high and it is difficult to achieve on-site detection. The laser fluorescence method has a high sensitivity of up to 0.02μg / L, but due to the large size of the laser, it is difficult to achieve portable detection; in addition, although ICP-MS can achieve multi-element detection, it can only be applied to laboratory environments and cannot be the preferred method for on-site portable equipment.

[0004] With the development of new solid light sources such as ultraviolet diodes (UV-LEDs) and laser diodes, the miniaturization of light sources has provided new ideas and development directions for the miniaturization and portability of detection equipment. At present, the shortest wavelength of UV-LEDs can reach 250nm, and the life span is 10,000 hours, but it is not as good as lasers in terms of light source intensity and light source convergence ability. However, since the on-site uranium measurement equipment only targets the uranium content in the discharged sewage, the general requirement is 0.05mg / L, which is much higher than the detection limit of the laser uranium meter, so the detection limit of the on-site uranium measurement equipment is not high. Therefore, UV-LED can be used as an excitation light source for on-site uranium measurement. In addition to patent reports, there have been no reports and applications of UV-LED in on-site uranium measurement. Summary of the invention

[0005] The purpose of the present invention is to address the above drawbacks and propose a high-sensitivity uranium content on-site measuring instrument based on multiple light sources. Based on the characteristic fluorescence principle of uranyl ion-fluorescence enhancer complex, multiple UV-LEDs are used as light sources, miniaturized photomultiplier tubes or silicon photomultipliers are used as photoelectric conversion elements, and fluorescent cuvettes are used as measuring cells. The light intensity of the excitation light source is increased, the detection limit can be reduced by several times, the technical difficulty of the sensitivity of the on-site uranium measuring instrument is solved, and the volume and power consumption of the equipment are greatly reduced.

[0006] The technical solution of the present invention is as follows:

[0007] A high-sensitivity uranium content on-site determination instrument based on multiple light sources, comprising four UV-LEDs, an LED temperature control module, a square bottom light-transmitting fluorescent cuvette, a photosensitive element, a fluorescence detection filter, a circuit system and a light-proof cover; the four UV-LEDs are fixed to a bottom plate inside the light-proof cover through a frame, and the fixed position ensures that the four UV-LEDs are respectively perpendicular to four vertical surfaces of the square bottom light-transmitting fluorescent cuvette, the main axis of the light emitted by the UV-LED is perpendicular to the vertical surface of the cuvette and is in the same plane, and the intersection of the main axis of the light is located in the square bottom light-transmitting fluorescent cuvette;

[0008] The outer edge of the square bottom light-transmitting fluorescent cuvette is wrapped and fixed by a rack, wherein the rack is hollow, and the optical fiber can pass through the rack to reach the four sides of the square bottom light-transmitting fluorescent cuvette; the rack is fixed on the photosensitive element, so that a gap is left between the bottom of the square bottom light-transmitting fluorescent cuvette and the upper part of the photosensitive element;

[0009] The photosensitive element is controlled by a circuit system, and the converted fluorescence signal is interpreted according to the frequency of the UV-LED pulse light source and the fluorescence lifetime of the uranyl ion, wherein the pulse frequency of the UV-LED and the photosensitive element extracting the light signal is consistent, and the phase delay of the photosensitive element extracting the light signal is 1-100μs.

[0010] The distance between each UV-LED and each side surface of the square bottom light-transmitting fluorescent cuvette is 0.1 to 10 mm.

[0011] The photosensitive element is a photomultiplier tube.

[0012] The photosensor is a silicon photomultiplier, and its sensitive light window is used to collect the fluorescence signal excited by the UV-LED. The photosensor is located at the bottom of the square bottom transparent fluorescence cuvette, and its axis direction forms an angle of 90° with the main axis of the UV-LED light.

[0013] The photosensitive element is a silicon photocell.

[0014] The photosensitive element is a photodiode.

[0015] The fluorescence detection filter is placed on the photosensitive element, the central wavelength range is 450-560nm, and the distance between the fluorescence detection filter and the bottom of the square bottom light-transmitting fluorescence cuvette is 0.1-10mm.

[0016] The central wavelength of the UV-LED is 240-400nm, the power is 10mW-4W, and it is powered by a constant current source.

[0017] The UV-LED power supply adopts a pulse modulation mode with a frequency of 10 to 1000 Hz and a duty cycle of 1:2 to 1:999.

[0018] The temperature of the UV-LED is precisely controlled by the LED temperature control module, and the temperature is room temperature to 70°C.

[0019] The beneficial effects of the present invention are:

[0020] The patent of this invention adopts multi-light source excitation, which has higher sensitivity and can adjust the light source intensity according to on-site needs to make the detection results more accurate. At the same time, the device is small in size and low in power, and can fully realize on-site detection of uranium in environmental samples.

[0021] The UV-LED used in the present invention is a new type of solid-state miniaturized light source, and the light it emits has good monochromaticity and a narrow spectral bandwidth (less than 10nm), is small in size and has a long life. In particular, the LED in the deep ultraviolet region (250-300nm) is used, which just falls on the optimal excitation wavelength of the complex of uranyl ion and fluorescence enhancer, and the excited fluorescence is stronger. The optical noise and fluctuation caused by the LED are very small, which is particularly suitable for the measurement of weak fluorescence signals, effectively improving the signal-to-noise ratio and improving the sensitivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a top view of the high-sensitivity uranium content on-site measuring instrument based on multiple light sources of the present invention;

[0023] Figure 2 It is a partial three-dimensional schematic diagram of the patent of this invention.

[0024] In the figure: 1, UV-LED; 2, square bottom transparent cuvette; 3, photosensitive element; 4, LED temperature control module; 5, circuit system; 6, fluorescence detection filter 6. DETAILED DESCRIPTION

[0025] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0026] A high-sensitivity on-site uranium content determination instrument based on multiple light sources comprises four UV-LEDs 1, an LED temperature control module 4, a square bottom light-transmitting fluorescent cuvette 2, a photosensitive element 3, a fluorescence detection filter 6, a circuit system 5 and a light-proof cover. The four UV-LEDs are fixed to the bottom plate inside the light-proof cover through a rack, and the fixed position ensures that the four UV-LEDs are respectively perpendicular to the four vertical surfaces of the square bottom light-transmitting fluorescent cuvette 2, and the main axis of the light emitted by the UV-LED 1 is perpendicular to the vertical surface of the cuvette and is in the same plane, and the intersection of the main axis of the light is located in the square bottom light-transmitting fluorescent cuvette 2. The outer edge of the square bottom light-transmitting fluorescent cuvette 2 is wrapped and fixed by the rack, and the rack is a hollow style, and the optical fiber can pass through the rack to reach the four surfaces of the square bottom light-transmitting fluorescent cuvette 2; the rack is fixed on the photosensitive element 3, so that a gap is left between the bottom of the square bottom light-transmitting fluorescent cuvette 2 and the upper part of the photosensitive element 3.

[0027] The distance between each UV-LED 1 and each side surface of the square bottom light-transmitting fluorescent cuvette 2 is 0.1 to 10 mm.

[0028] The photosensitive element 3 can be a photomultiplier tube, a silicon photomultiplier, a silicon photocell, or a photodiode. The sensitive light window of the photosensitive element 3 is used to collect the fluorescence signal excited by the UV-LED 1. The photosensitive element 3 is located at the bottom of the square bottom light-transmitting fluorescence cuvette 2, and its axis direction forms a 90° angle with the main axis of the light of the UV-LED 1.

[0029] The central wavelength of the UV-LED1 is 240-400nm, the power is 10mW-4W, and it is powered by a constant current source. The UV-LED1 power supply adopts pulse modulation, with a frequency of 10-1000Hz and a duty cycle of 1:2-1:999. The UV-LED1 has the same lighting and off time under the control of the circuit system 5, and any number of 1-4 UV-LED1 can be selected to light up. The temperature of the UV-LED1 is precisely controlled by the LED temperature control module 4, and the temperature is room temperature to 70°C.

[0030] The fluorescence detection filter 6 is placed on the photosensitive element 3, with a central wavelength range of 450-560 nm, and a distance between the fluorescence detection filter 6 and the bottom of the square bottom light-transmitting fluorescence cuvette 2 is 0.1-10 mm.

[0031] The photosensitive element 3 is controlled by a circuit system 5, and the converted fluorescence signal is interpreted according to the frequency of the UV-LED 1 pulse light source and the fluorescence lifetime of the uranyl ion, wherein the pulse frequency of the UV-LED 1 is consistent with that of the photosensitive element for extracting the light signal, and the phase delay of the photosensitive element for extracting the light signal is 1-100 μs.

[0032] The actual operation process is to take a certain amount of sample (such as river water or lake water) or standard solution, put it into a cuvette, then add a fluorescence enhancer in a quantitative manner, stir it evenly in the fluorescence cuvette, then put the fluorescence cuvette into the cuvette fixing device of the patent of the present invention, turn on the ultraviolet light emitting diode, detect the fluorescence intensity by the photosensitive element, and measure the uranium content in the sample by the standard curve method or the standard addition method.

[0033] Example 1

[0034] A high-sensitivity on-site uranium content determination instrument based on multiple light sources, wherein the excitation light sources are 4 UV-LEDs 1, the central wavelength of which is 360nm, the rated current is 100mA, the divergence angle is 120°, the power supply is 100Hz, and the duty cycle is 1:49. The UV-LED 1 adopts an aluminum heat sink, and due to the low duty cycle, the heat generation is very small, and it can be used through an ordinary heat sink. The distance between the UV-LED 1 and the square bottom transparent fluorescence cuvette 2 is 1mm. The central wavelength of the fluorescence detection filter 6 is 510nm, the bandwidth is 10nm, and the distance between the fluorescence detection filter 6 and the photomultiplier tube is 1mm. Since the fluorescence lifetime of the complex of uranyl ions and fluorescence enhancers is tens to hundreds of μs, 50μs is selected as the delay time. The fluorescence signal of the uranyl ion is synchronously delayed pulsed according to the pulse characteristics of the light source. The detection repeatability of the instrument for uranyl ions is less than 8%, and the detection sensitivity reaches 0.2μg / L, which is less than 50μg / L of the wastewater discharge standard.

[0035] Example 2

[0036] A high-sensitivity on-site uranium content determination instrument based on multiple light sources, wherein the excitation light sources are two UV-LEDs 1, the central wavelength of which is 320nm, the rated current is 50mA, the light emitting diode power supply is 500Hz, and the duty cycle is 1:19. The UV-LED 1 adopts an aluminum heat sink, which does not require a fan, has a low power and a stable temperature. The light intensity of the ultraviolet light emitted by the UV-LED 1 light source can be detected in real time, and the detector can be directly measured after being turned on, eliminating the time consumed by the preheating operation. The distance between the UV-LED 1 and the square bottom light-transmitting fluorescent cuvette 2 is 0.5mm. The central wavelength of the fluorescence detection filter 6 is 510nm, the bandwidth is 10nm, and the distance between the fluorescence detection filter 6 and the photomultiplier tube is 0.5mm. The circuit system collects the fluorescence signal in a pulsed manner following the light source, and the delay time is 50μs. The detection repeatability of the portable device for uranyl ions is less than 4%, and the detection sensitivity reaches 0.5μg / L, which is less than the 50μg / L of the wastewater discharge standard.

[0037] The above-mentioned embodiments are only descriptions of the preferred implementation methods of the present invention, and are not intended to limit the scope of the present invention. Instead, they are intended to be consistent with the broadest scope consistent with the general principles and novel features disclosed herein. Without departing from the spirit of the present invention, various modifications and improvements made by ordinary technicians in this field to the technical solution of the present invention should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A high-sensitivity on-site uranium content determination instrument based on multiple light sources, comprising four UV-LEDs, an LED temperature control module, a square bottom light-transmitting fluorescence cuvette, a photosensitive element, a fluorescence detection filter, a circuit system and a light-proof cover; characterized in that: The four UV-LEDs are fixed to the bottom plate inside the light-proof cover through a frame, and the fixed position ensures that the four UV-LEDs are respectively perpendicular to the four vertical surfaces of the square bottom light-transmitting fluorescent cuvette, the main axis of the light emitted by the UV-LED is perpendicular to the vertical surface of the cuvette and is in the same plane, and the intersection point of the main axis of the light is located in the square bottom light-transmitting fluorescent cuvette; The outer edge of the square bottom light-transmitting fluorescent cuvette is wrapped and fixed by a rack, wherein the rack is hollow, and the optical fiber can pass through the rack to reach the four sides of the square bottom light-transmitting fluorescent cuvette; the rack is fixed on the photosensitive element, so that a gap is left between the bottom of the square bottom light-transmitting fluorescent cuvette and the upper part of the photosensitive element; The photosensitive element is controlled by a circuit system, and the converted fluorescence signal is interpreted according to the frequency of the UV-LED pulse light source and the fluorescence lifetime of the uranyl ion, wherein the pulse frequency of the UV-LED and the light signal extracted by the photosensitive element are consistent, and the phase delay of the light signal extracted by the photosensitive element is 1-100 μs; The fluorescence detection filter is placed on the photosensitive element, the central wavelength range is 450-560nm, and the distance between the fluorescence detection filter and the bottom of the square bottom light-transmitting fluorescence cuvette is 0.1-10mm.

2. A high-sensitivity uranium content on-site measuring instrument based on multiple light sources as claimed in claim 1, characterized in that: The distance between each UV-LED and each side surface of the square bottom light-transmitting fluorescent cuvette is 0.1 to 10 mm.

3. A high-sensitivity uranium content on-site measuring instrument based on multiple light sources as claimed in claim 1, characterized in that: The photosensitive element is a photomultiplier tube.

4. A high-sensitivity on-site uranium content measuring instrument based on multiple light sources as claimed in claim 3, characterized in that: The photosensor is a silicon photomultiplier, and its sensitive light window is used to collect the fluorescence signal excited by the UV-LED. The photosensor is located at the bottom of the square bottom transparent fluorescence cuvette, and its axis direction forms an angle of 90° with the main axis of the UV-LED light.

5. A high-sensitivity on-site uranium content measuring instrument based on multiple light sources as claimed in claim 3, characterized in that: The photosensitive element is a silicon photocell.

6. A high-sensitivity on-site uranium content measuring instrument based on multiple light sources as claimed in claim 3, characterized in that: The photosensitive element is a photodiode.

7. A high-sensitivity on-site uranium content measuring instrument based on multiple light sources as claimed in any one of claims 1 to 6, characterized in that: The central wavelength of the UV-LED is 240-400nm, the power is 10mW-4W, and it is powered by a constant current source.

8. A high-sensitivity on-site uranium content measuring instrument based on multiple light sources as claimed in any one of claims 1 to 6, characterized in that: The UV-LED power supply adopts a pulse modulation mode with a frequency of 10 to 1000 Hz and a duty cycle of 1:2 to 1:

999.

9. A high-sensitivity on-site uranium content measuring instrument based on multiple light sources as claimed in any one of claims 1 to 6, characterized in that: The temperature of the UV-LED is precisely controlled by the LED temperature control module, and the temperature is room temperature to 70°C.

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