Preparation device and preparation method of mercury isotope diluent

Abstract

The invention provides a preparation device and a preparation method of a mercury isotope diluent. The preparation device of the mercury isotope diluent comprises a digestion unit, a reduction unit and an enrichment unit which are connected in sequence, the digestion unit comprises a digestion reactor, an oxidant storage container and an oxidant extraction device; the reduction unit comprises a reducing agent storage container, a digestion solution extraction device, a reducing agent extraction device and a gas-liquid separator; a strong oxidant is stored in the oxidant storage container; a reducing agent is stored in the reducing agent storage container; components in the digestion reactor, the digestion solution extraction device and the enrichment unit, which are in contact with mercury, are made of Teflon or borosilicate glass materials. According to the method disclosed by the invention, 199Hg and 200Hg of high-concentration mercury can be extracted from fish meat enriched with mercury through a digestion reaction and a reduction enrichment process, and the mercury isotope diluent is prepared.

Description

Technical Field

[0001] The invention relates to the technical field of environmental science analysis and environmental detection, and in particular to a preparation device and a preparation method of a mercury isotope diluent. Background Art

[0002] Mercury is a toxic and harmful heavy metal element that is ubiquitous in nature. It can diffuse from emission sources or migrate long distances with atmospheric activities and settle in other areas, leading to serious ecological safety problems and human health exposure risks. Due to the special physical and chemical properties of mercury, its biogeochemical cycle process is extremely complex. In addition, due to the lack of effective measurement technology and means, many migration and transformation processes of mercury in the environment are still unclear. It is urgent to develop effective research methods to provide technical support for reducing mercury emissions and controlling mercury pollution, protecting ecological safety and human health.

[0003] In recent years, due to the rapid improvement and development of plasma mass spectrometry analysis methods and instrument accuracy, the analysis methods of mercury isotopes have been developed, gradually matured and widely used in mercury isotope analysis of environmental samples. At present, the measurement accuracy of mercury isotopes can generally reach ±0.1‰ using the most advanced multi-collector inductively coupled plasma mass spectrometer (MC-I CP-MS). Therefore, the environmental transfer and transformation process of mercury can be studied by measuring and analyzing the mercury isotope composition and ratio of environmental samples. According to the isotope dilution mass spectrometry technology and methods, adding a single mercury isotope or a sample of a naturally abundant and abnormally high mercury isotope to the environmental sample as a mercury isotope diluent can change the composition of mercury isotopes in the environmental sample. Then, the isotope ratio of the environmental sample under various environmental conditions and processes is measured, so that the migration and transformation process of mercury in the environment can be traced and studied in great detail.

[0004] However, the preparation of mercury isotope diluent is extremely difficult. Its traditional preparation method mainly uses isotope separation and enrichment technology to separate and enrich one isotope of mercury from other isotopes of the element. This separation technology is extremely complex and requires extremely high instrumentation and process technology levels.

[0005] At present, the preparation technology of mercury isotope diluent mainly adopts isotope separation and concentration technology, the principle of which is to use the extremely slight mass difference of various isotopes of the same element to separate, concentrate and prepare, mainly including gas diffusion method, centrifugal method and laser method, etc. Gas diffusion method and centrifugal method are both relatively mature, and the purity of the isotope prepared by them depends on the advanced level and scale of the instruments and equipment.

[0006] In addition, there are some chemical methods that can separate and enrich isotopes, but the same element has the same number of protons in the nucleus and the same number of electrons outside the nucleus, so their chemical properties are very similar, and separation is extremely difficult. Therefore, mercury isotope separation and enrichment technology is an extremely challenging technology. Summary of the invention

[0007] The present invention provides a preparation device and a preparation method of a mercury isotope diluent, the purpose of which is to solve the technical problem of difficulty in preparing the mercury isotope diluent in the background technology.

[0008] In order to achieve the above-mentioned object, the present invention provides a device for preparing a mercury isotope diluent, comprising a digestion unit, a reduction unit and an enrichment unit connected in sequence;

[0009] The digestion unit comprises a digestion reactor, an oxidant storage container and an oxidant extraction device, wherein the oxidant extraction device can extract the solution or gas in the oxidant storage container into the digestion reactor, and a stirrer is provided in the digestion reactor;

[0010] The reduction unit includes a reducing agent storage container, a digestion liquid extraction device, a reducing agent extraction device and a gas-liquid separator, wherein the digestion liquid extraction device can extract the solution or gas in the digestion reactor into the gas-liquid separator, and the reducing agent extraction device can extract the solution or gas in the reducing agent storage container into the gas-liquid separator;

[0011] The oxidant storage container stores a strong oxidant;

[0012] The reducing agent storage container stores a reducing agent;

[0013] The digestion reactor, the digestion solution extraction device and the components in the enrichment unit are all made of Teflon or borosilicate glass.

[0014] Preferably, the oxidant extraction device, the digestion solution extraction device and the reducing agent extraction device are all pipes provided with peristaltic pumps.

[0015] Preferably, the gas-liquid separator comprises a gas-liquid separation tube and a waste liquid bottle, and the waste liquid bottle is connected to the liquid end of the gas-liquid separation tube.

[0016] Preferably, the enrichment unit comprises a drying tube and a mercury enrichment tube, one end of the drying tube is connected to the gas end of the gas-liquid separation tube, and the other end of the drying tube is connected to the mercury enrichment tube, and a mercury adsorbent is provided in the mercury enrichment tube.

[0017] Preferably, the drying tube is provided with soda lime desiccant.

[0018] Preferably, the mercury adsorbent is modified activated carbon with a particle size of less than 1 mm, quartz sand gold-plated particles or pure gold particles.

[0019] Preferably, the enrichment unit further comprises a three-way valve and an environmental sample pipe fitting, and the three-way valve connects the drying tube, the gas-liquid separator and the environmental sample pipe fitting.

[0020] Preferably, the strong oxidant can be concentrated nitric acid of process ultrapure or analytical purity, or concentrated nitric acid and concentrated sulfuric acid in a volume ratio of 4:1, or aqua regia, or concentrated nitric acid, peroxide and perchloric acid in a volume ratio of 5:10:1, and the reducing agent is stannous chloride.

[0021] The present invention provides a method for preparing a device for preparing a mercury isotope diluent, comprising the following steps:

[0022] Step S1, sampling: sampling and preserving the natural sample enriched with mercury;

[0023] Step S2, drying: taking the natural sample and placing it in a Teflon tray, and placing it in a freeze dryer for freeze drying;

[0024] Step S3, grinding: putting the freeze-dried natural sample into an agate mortar for manual grinding, or putting it into an agate grinder for automatic mechanical grinding, grinding the natural sample into a powder of 50-100 mesh, and then taking 0.5-2 grams of the ground natural sample powder to measure its total mercury concentration, so as to obtain the total mercury dose for subsequent preparation of mercury isotope diluent;

[0025] Step S4, digestion: weigh 0.1-1 g of natural sample powder and put it into a digestion reactor, draw a strong oxidant into the digestion reactor, and dissolve the natural sample powder into the strong oxidant solution under the stirring of a stirrer. After 3-10 hours of dissolution, the mercury in the natural sample is oxidized into ionic mercury and distributed in the strong oxidant solution;

[0026] Step S5, reduction: extracting the digestion solution in the digestion reactor and the reducing agent in the reducing agent storage container into a gas-liquid separator for mixing, and reducing the mercury ions in the digestion solution into gaseous elemental mercury;

[0027] Step S6, enrichment: obtaining the prepared mercury isotope diluent in the enrichment unit.

[0028] Preferably, in step S1, the natural sample is specifically fish meat enriched with mercury, and the sampling is specifically: slicing the fish meat enriched with mercury, placing it in a cold storage or refrigerator, and storing it in a low temperature environment below -10°C.

[0029] The device for preparing a mercury isotope diluent of the present invention has the following beneficial effects:

[0030] Through the digestion reaction and reduction collection process, it is possible to extract high concentrations of chloranthene from natural samples, such as marine carnivorous fish at the top of the food chain. 199 Hg and 200 Hg in fish meat, extract high concentration 199 Hg and 200 Hg of mercury, extracting mercury isotope diluent, and applying it to trace the migration and transformation process of environmental mercury, thus providing a new, simple and effective mercury isotope diluent preparation technology and method for the research in the field of environmental mercury. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a structural schematic diagram of a preferred embodiment of a device for preparing a mercury isotope diluent of the present invention;

[0032] Figure 2 For application Figure 1 A flow chart of a method for preparing a mercury isotope diluent using a device for preparing a mercury isotope diluent is shown;

[0033] in,

[0034] 11. digestion reactor; 12. oxidant storage container; 13. oxidant extraction device; 111. stirring bar;

[0035] 21. Reducing agent storage container; 22. Digestion liquid extraction device; 23. Reducing agent extraction device; 24. Gas-liquid separator;

[0036] 241. Gas-liquid separation tube; 242. Waste liquid bottle;

[0037] 31. Drying tube; 32. Mercury enrichment tube; 33. Three-way valve; 34. Environmental sample pipe fittings. DETAILED DESCRIPTION

[0038] In order to make the technical problems, technical solutions and advantages to be solved by the present invention more clear, a detailed description will be given below with reference to the accompanying drawings and specific embodiments.

[0039] In view of the existing problems, the present invention provides a device for preparing a mercury isotope diluent.

[0040] In one embodiment, a device for preparing a mercury isotope diluent, such as Figure 1 As shown, it includes a digestion unit, a reduction unit and an enrichment unit connected in sequence;

[0041] The digestion unit includes a digestion reactor 11, an oxidant storage container 12, and an oxidant extraction device 13. The oxidant extraction device 13 can extract the solution or gas in the oxidant storage container 12 into the digestion reactor 11, and the digestion reactor 11 is provided with a stirrer 111;

[0042] The reduction unit includes a reducing agent storage container 21, a digestion liquid extraction device 22, a reducing agent extraction device 23 and a gas-liquid separator 24. The digestion liquid extraction device 22 can extract the solution or gas in the digestion reactor 11 into the gas-liquid separator 24, and the reducing agent extraction device 23 can extract the solution or gas in the reducing agent storage container 21 into the gas-liquid separator 24;

[0043] The oxidant storage container 12 stores a strong oxidant, which may be ultrapure or analytically pure concentrated nitric acid, or concentrated nitric acid and concentrated sulfuric acid in a volume ratio of 4:1, or aqua regia, or concentrated nitric acid, peroxygen solution and perchloric acid in a volume ratio of 5:10:1;

[0044] The reducing agent storage container 21 stores a reducing agent, wherein the reducing agent is stannous chloride with a concentration of 100-200 g / L;

[0045] The digestion reactor 11, the digestion solution extraction device 22 and the components in the enrichment unit are all made of Teflon or borosilicate glass.

[0046] The working principle of the device for extracting mercury isotopes is:

[0047] The oxidant is extracted into the digestion reactor 11 by the oxidant extraction device 13. Under the stirring of the magnetic stirrer, the oxidant reacts with the fish meat powder in the digestion reactor 11. After 3-10 hours of dissolution reaction, the mercury in the fish meat is completely oxidized into ionic mercury distributed in the oxidant solution.

[0048] After digestion is completed, the digestion liquid extraction device 22 extracts the reacted digestion liquid into the gas-liquid separator 24, and the reducing agent extraction device 23 extracts the stannous chloride solution in the reduction storage container 21 into the gas-liquid separator 24. The digestion liquid is mixed with the stannous chloride solution. During the mixing process, the stannous chloride reduces the mercury ions in the digestion liquid into gaseous elemental mercury, and the gaseous mercury is then enriched by an enrichment unit or used directly.

[0049] Based on the above embodiments, in this embodiment, the oxidant extraction device 13, the digestion solution extraction device 22 and the reducing agent extraction device 23 are all pipes provided with peristaltic pumps.

[0050] The gas-liquid separator 24 includes a gas-liquid separation tube 241 and a waste liquid bottle 242. The waste liquid bottle 242 is connected to the liquid end of the gas-liquid separation tube 24.

[0051] As a further improvement of this embodiment, the enrichment unit includes a drying tube 31 and a mercury enrichment tube 32. One end of the drying tube 31 is connected to the gas end of the gas-liquid separation tube 24, and the other end of the drying tube 31 is connected to the mercury enrichment tube 32, in which a mercury adsorbent is provided.

[0052] Soda lime desiccant is arranged in the drying tube 31. The mercury adsorbent is modified activated carbon with a particle size less than 1 mm, quartz sand gold-plated particles or pure gold particles.

[0053] After the gaseous elemental mercury evaporates from the mixed liquid, it passes through the drying tube 31 to remove moisture, and then passes through the mercury enrichment tube 32 to be enriched on the mercury adsorbent. The waste gas is discharged from the gas outlet, and the waste liquid is discharged from the bottom of the gas-liquid separator 24 into the waste liquid bottle 242.

[0054] When the prepared mercury isotope diluent is needed for environmental mercury research, it is only necessary to heat the mercury enrichment tube 32 to 450-800°C, so that the mercury in the mercury enrichment tube 32 can be decomposed, and then carried out by the carrier gas and loaded into the gas sample that needs to be traced. The decomposed mercury can also be loaded into an oxidant again to become a liquid mercury isotope diluent, and then added to the liquid sample that needs to be traced.

[0055] As a further improvement of this embodiment, the mercury isotope enrichment unit further includes a three-way valve 33 and an environmental sample pipe 34. The three-way valve 33 connects the drying tube 31, the gas-liquid separator 24 and the environmental sample pipe 34.

[0056] The gaseous elemental mercury extracted from the gas-liquid separation tube 24 can be directly added to the environmental sample that needs to be traced and studied through the environmental sample pipe 34 after passing through the three-way valve 33 .

[0057] The present invention provides a method for preparing a mercury isotope diluent using the device for preparing the mercury isotope diluent, such as Figure 2 As shown, the following steps are included:

[0058] Step S1, sampling: Slice the fish meat enriched with mercury, place it in a cold storage or refrigerator, and store it in a low temperature environment below -10°C to prevent the fish meat from rotting and the mercury from volatilizing and losing, waiting for the next step of processing.

[0059] Step S2, drying: 500-100 grams of fish fillets are placed in a Teflon tray, the fish fillets are spread flat on the surface of the tray, and placed in a freeze dryer for freeze drying; freeze drying can prevent the fish from rotting and mercury from volatilizing and losing during the drying process, and is convenient for the next step of grinding.

[0060] Step S3, grinding: putting the freeze-dried fish meat into an agate mortar for manual grinding, or putting it into an agate grinder for automatic mechanical grinding, grinding the fish meat into 50-100 mesh powder, and then taking 0.5-2 grams of the ground fish meat powder to measure its total mercury concentration, so as to obtain the total mercury dose for subsequent preparation of mercury isotope diluent;

[0061] Step S4, digestion: weigh 0.1-1 g (accurate to 0.0001 g) of fish powder and put it into a digestion reactor 11, draw a strong oxidant into the digestion reactor, and dissolve the fish powder into the strong oxidant solution under the stirring of a magnetic stirrer 111. After 3-10 hours of dissolution, the mercury in the fish is oxidized into ionic mercury and distributed in the strong oxidant solution;

[0062] Step S5, reduction: extracting the digestion solution in the digestion reactor 11 and the reducing agent in the reducing agent storage container 21 into the gas-liquid separator 24 for mixing, and reducing the mercury ions in the digestion solution into gaseous elemental mercury;

[0063] Step S6, enrichment: obtaining the prepared mercury isotope diluent in the enrichment unit.

[0064] Through the above steps, mercury in the fish meat can be extracted and enriched in the mercury enrichment tube 32, so as to prepare a mercury isotope diluent. The mass of the prepared mercury isotope diluent can be obtained according to the measured total mercury concentration in the fish meat and the weight of the digested fish meat.

[0065] The technology of the present invention has been successfully applied to the tracing and research of atmospheric mercury in the Ailao Mountain forest. As shown in Table 1, the mercury isotope diluent prepared by the present invention was added to the climate chamber of the Ailao Mountain forest. After it was mixed with the atmosphere in the climate chamber (mixing time was greater than 2 hours), 6 atmospheric samples in the climate chamber were collected and their mercury isotope ratios were measured by MC-I CP-MS. The results showed that the mercury isotope ratio of atmospheric mercury in the climate chamber was 1.3477 W·m-1. 199 Hg and 200 The average values ​​of Hg non-mass fractionation were 1.55‰ and 0.17‰, which were significantly higher than the same mercury isotope ratios in the normal atmosphere of the Ailao Mountain forest ( 199 Hg and 200The average values ​​of Hg non-mass fractionation are -0.2‰ and -0.06‰ respectively). This result shows that the mercury isotope diluent prepared by the present invention can significantly change the isotope ratio of atmospheric mercury, and can be applied to in-depth research on environmental processes such as atmospheric mercury migration and transformation, dry and wet deposition, exchange and migration with land and vegetation. The technical method of the present invention can achieve the effect of adding high-purity single mercury isotope, which is effective and reliable.

[0066]

[0067] Table 1

[0068] The device and method for preparing a mercury isotope diluent of the present invention have the following beneficial effects:

[0069] Through the digestion reaction and reduction collection process, it is possible to extract high concentrations of chloranthene from natural samples, such as marine carnivorous fish at the top of the food chain. 199 Hg and 200 Hg in fish meat, extract high concentration 199 Hg and 200 Hg of mercury, extracting mercury isotope diluent, and applying it to trace the migration and transformation process of environmental mercury, thus providing a new, simple and effective mercury isotope diluent preparation technology and method for the research in the field of environmental mercury.

[0070] Firstly, the present invention avoids the use of isotope separation technology with very high technical and industrial level requirements and extremely complex production process to prepare a single mercury isotope, and adopts a very simple physical and chemical method to prepare a mercury isotope diluent. The technical method is simple, the preparation process is relatively easy to implement, and the difficulty and cost of preparing the mercury isotope diluent are greatly reduced;

[0071] Second, it solves the problem of the difficulty and high cost of purchasing single mercury isotopes. Mercury isotope diluents can be obtained very simply and quickly, which greatly facilitates the research in the field of environmental mercury and greatly reduces the cost of technology and research.

[0072] Third, compared with the use of a single mercury isotope as a diluent, the present invention can change the addition method according to the experimental conditions, and can be added in liquid or gaseous form, and the amount added can be quickly adjusted by a peristaltic pump. During the application of a single mercury isotope, multi-stage dilution and oxidation-reduction are required, which can easily cause the loss of mercury isotope samples, making the amount added to the environmental sample inaccurate;

[0073] Fourth, the mercury isotope diluent prepared by the present invention can be stored for a long time after being adsorbed by the mercury enrichment tube, and the enriched mercury will basically not be lost, and it is also very convenient to carry to the field to carry out experiments and research, while the diluent of a single mercury isotope needs to be configured into a liquid mercury standard solution, which is very inconvenient to bring to the field, and the mercury standard solution will lose more seriously if it is left for a long time;

[0074] Fifth, the device of the present invention can also be directly used on site, and the gaseous mercury reduced by the gas-liquid separator 24 is directly introduced into the gas environment sample to be added, saving the cost of enrichment, storage and transportation of mercury isotope diluent;

[0075] Sixth, the mercury isotope diluent of the present invention is taken from natural biological samples, and has relatively little pollution and impact on the environment after being added into the environment.

[0076] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A device for preparing a mercury isotope diluent, characterized in that: It includes a digestion unit, a reduction unit and an enrichment unit connected in sequence; The digestion unit comprises a digestion reactor (11), an oxidant storage container (12) and an oxidant extraction device (13), wherein the oxidant extraction device (13) can extract the solution or gas in the oxidant storage container (12) into the digestion reactor (11), and a stirrer (111) is provided in the digestion reactor (11); The reduction unit comprises a reducing agent storage container (21), a digestion liquid extraction device (22), a reducing agent extraction device (23) and a gas-liquid separator (24); the digestion liquid extraction device (22) can extract the solution or gas in the digestion reactor (11) into the gas-liquid separator (24); and the reducing agent extraction device (23) can extract the solution or gas in the reducing agent storage container (21) into the gas-liquid separator (24); The oxidant storage container (12) stores a strong oxidant; The reducing agent storage container (21) stores a reducing agent; The digestion reactor (11), the digestion liquid extraction device (22) and the components in the enrichment unit are all made of Teflon or borosilicate glass.

2. The device for preparing a mercury isotope diluent according to claim 1, characterized in that: The oxidant extraction device (13), the digestion liquid extraction device (22) and the reducing agent extraction device (23) are all pipe fittings provided with peristaltic pumps.

3. The device for preparing a mercury isotope diluent according to claim 1, characterized in that: The gas-liquid separator (24) comprises a gas-liquid separation tube (241) and a waste liquid bottle (242), and the waste liquid bottle (242) is connected to the liquid end of the gas-liquid separation tube (241).

4. The device for preparing a mercury isotope diluent according to claim 1, characterized in that: The enrichment unit comprises a drying tube (31) and a mercury enrichment tube (32); one end of the drying tube (31) is connected to the gas end of the gas-liquid separation tube (24); the other end of the drying tube (31) is connected to the mercury enrichment tube (32); and a mercury adsorbent is provided in the mercury enrichment tube (32).

5. The device for preparing a mercury isotope diluent according to claim 4, characterized in that: The drying tube (31) is provided with soda lime desiccant.

6. The device for preparing a mercury isotope diluent according to claim 4, characterized in that: The mercury adsorbent is modified activated carbon with a particle size of less than 1 mm, quartz sand gold-plated particles or pure gold particles.

7. The device for preparing a mercury isotope diluent according to claim 4, characterized in that: The enrichment unit further comprises a three-way valve (33) and an environmental sample pipe (34), wherein the three-way valve (33) is connected to the drying pipe (31), the gas-liquid separator (24) and the environmental sample pipe (34).

8. The device for preparing a mercury isotope diluent according to claim 1, characterized in that: The strong oxidant can be concentrated nitric acid of process ultrapure or analytical pure, or concentrated nitric acid and concentrated sulfuric acid in a volume ratio of 4:1, or aqua regia, or concentrated nitric acid, peroxide and perchloric acid in a volume ratio of 5:10:1, and the reducing agent is stannous chloride.

9. A method for preparing a mercury isotope diluent preparation device using any one of claims 1 to 8, characterized in that: The steps include: Step S1, sampling: sampling and preserving the natural sample enriched with mercury; Step S2, drying: taking the natural sample and placing it in a Teflon tray, and placing it in a freeze dryer for freeze drying; Step S3, grinding: putting the freeze-dried natural sample into an agate mortar for manual grinding, or putting it into an agate grinder for automatic mechanical grinding, grinding the natural sample into a powder of 50-100 mesh, and then taking 0.5-2 grams of the ground natural sample powder to measure its total mercury concentration, so as to obtain the total mercury dose for subsequent preparation of mercury isotope diluent; Step S4, digestion: weigh 0.1-1 g of natural sample powder and put it into a digestion reactor (11), draw a strong oxidant into the digestion reactor (11), and dissolve the natural sample powder into the strong oxidant solution under the stirring of a stirrer. After 3-10 hours of dissolution, the mercury in the natural sample is oxidized into ionic mercury and distributed in the strong oxidant solution; Step S5, reduction: extracting the digestion solution in the digestion reactor (11) and the reducing agent in the reducing agent storage container (21) into the gas-liquid separator (24) for mixing, and reducing the mercury ions in the digestion solution into gaseous elemental mercury; Step S6, enrichment: obtaining the prepared mercury isotope diluent in the enrichment unit.

10. The method for preparing a mercury isotope diluent according to claim 9, characterized in that: In the step S1, the natural sample is specifically fish meat enriched with mercury, and the sampling is specifically: slicing the fish meat enriched with mercury, placing it in a cold storage or refrigerator, and storing it in a low temperature environment below -10°C.

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