Collection device and analysis method for sulfur isotope measurement of sulfur dioxide in atmosphere

Abstract

The invention belongs to the technical field of isotope measurement, and particularly relates to a collection device and analysis method for sulfur isotope measurement of sulfur dioxide in atmosphere, the collection device comprises a gas inlet bottle, a first drying tube, a filter, a sulfuric acid vapor collector, a sulfur dioxide collector, an ice bath device, a second drying tube, a flowmeter and a vacuum pump which are connected in sequence. The collection device adopts an integrated design, integrates condensation, oxidation and precipitation functions, simplifies a sample pretreatment process, avoids cross contamination, improves the analysis accuracy and efficiency, performs sulfur isotope analysis with a NanoSIMS (Nano Secondary Ion Mass Spectrometer) when in use, remarkably reduces the sample amount demand, and is suitable for large-scale popularization and application. And the sampling time is shortened to an hour level, so that short-time monitoring is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of isotope measurement, and particularly relates to a collection device and an analysis method for measuring sulfur isotopes of sulfur dioxide in the atmosphere. Background Art

[0002] SO 2 is quickly oxidized in the atmosphere and forms sulfate aerosols through homogeneous oxidation in the gas phase or heterogeneous oxidation in the liquid phase. Sulfate aerosols are an important component of fine particles in urban atmosphere and also one of the important sources of acid deposition. Therefore, determining the sources of atmospheric SO 2 and its transformation process in the atmosphere is of great significance for quantitatively evaluating the physical and chemical effects of regional environmental sulfate aerosols and understanding the impacts of atmospheric SO 2 and sulfate aerosols on the global environment. Due to the "fingerprint" characteristics of the stable sulfur isotope composition, sulfur isotope tracing technology has been widely applied to research such as sulfur cycling and sulfur source analysis in the environmental field. By analyzing the sulfur isotope composition in SO 2 and sulfate aerosols, it is possible to effectively indicate the source of SO 2 and the transformation path of SO 2 oxidized to form sulfate.

[0003] Currently, for the determination of sulfur isotopes in SO 2 , the alkali flake method is mainly used for collecting SO 2 gas samples. According to different sampling methods, the sampling process can be divided into passive sampling and active sampling. Passive sampling is to place the filter membrane with the hairy side facing outwards in a plastic sampling dish, press the edge with a plastic washer, and fix the filter membrane facing downwards in the sampling rack. The sampling placement time is usually 30±2d. Active sampling usually uses a suspended particulate matter sampler for collection. During sampling, an unsoaked clean glass fiber filter membrane is placed in the upper layer of the double-layer sampler, and a soaked glass fiber filter membrane is placed in the lower layer. The upper layer collects aerosols, and the lower layer collects atmospheric SO 2 . The sampling flow rate is usually 100 - 1000 L / min, and the sampling duration ranges from 1 day to several days. After the sample collection is completed, the filter membrane needs to be cut into pieces, placed in ultrapure water for extraction and filtration, and then H 2 O 2 is added to oxidize sulfite to sulfate. Subsequently, BaCl 2 solution is added, and BaSO 4 precipitation occurs. The precipitate is filtered and dried to obtain pure BaSO 4 precipitate. The obtained BaSO 4 precipitate needs to be further purified and undergoes processes such as weighing, loading, and vacuum pumping. Then, vanadium pentoxide (V 2 O 5)At 980 °C, BaSO 4 is converted into sulfur dioxide (SO 2 ), purified and collected SO 2 , and SO 2 is introduced into a gas isotope mass spectrometer for sulfur isotope composition analysis.

[0004] However, the existing technologies have the following disadvantages: (1) Low sampling efficiency: Passive sampling relies on the natural diffusion of gas to the filter membrane. In a low-concentration environment, it takes a long time to accumulate enough SO 2 , with a long sampling period and unable to reflect the dynamic of sudden pollution in hours to days in real time.

[0005] (2) High sample demand: Traditional gas isotope mass spectrometers (such as IRMS) have limited sensitivity and require a sufficient amount of BaSO 4 precipitation (not less than 1 mg) to ensure the signal-to-noise ratio, resulting in the need to extend the sampling time or increase the flow rate in a low-concentration environment, unable to meet the rapid analysis requirements of trace sulfur.

[0006] (3) Complicated sample pretreatment: During the sample collection and preparation process, steps such as filter membrane soaking (K 2 CO 3 + glycerol), water extraction, H 2 O 2 oxidation, BaCl 2 precipitation, filtration and drying are required in sequence. The operation is cumbersome, prone to sample loss or contamination. At the same time, gaseous sulfuric acid in the atmosphere may also be collected on the filter membrane, interfering with the sulfur isotope analysis in SO 2 .

[0007] (4) Risk of sulfur isotope fractionation: During the process of the filter membrane (treated with K 2 CO 3 ) absorbing atmospheric SO 2 , the contact time between the filter membrane and the collected gas is short. If the SO 2 gas cannot be 100% absorbed, sulfur isotopes may have different adsorption efficiencies due to mass differences (such as 32 S and 34 S), resulting in fractionation during the sampling process. Summary of the Invention

[0008] In view of the above deficiencies of the existing technologies, the present invention provides a collection device and analysis method for measuring sulfur isotopes of sulfur dioxide in the atmosphere, solving the problems of low sampling efficiency, complicated pretreatment and sulfur isotope fractionation existing in the existing technologies.

[0009] To achieve the above object, the technical solution adopted by the present invention is: Provided is a collection device and an analysis method for measuring sulfur isotopes of sulfur dioxide in the atmosphere, including an air inlet bottle, a first drying tube, a filter, a sulfuric acid vapor collector, a sulfur dioxide collector, an ice bath device, a second drying tube, a flow meter and a vacuum pump connected in sequence; The sulfuric acid vapor collector includes a first inner tube and a first outer tube arranged outside the first inner tube. One side of the upper end of the first outer tube is provided with a condensate inlet, and one side of the lower end of the first outer tube is provided with a condensate outlet. The other side of the upper ends of the first inner tube and the first outer tube is provided with a first air outlet, and the other side of the lower ends of the first inner tube and the first outer tube is provided with a first air inlet. Barbs are arranged inside the first inner tube.

[0010] The beneficial effects of adopting the above technical solution are as follows: The vacuum pump in the collection device is used to provide a negative pressure environment to enable air to enter the device smoothly and perform subsequent collection and processing. The flow meter is used to measure and control the air flow rate entering the collection device. At the same time, the sampling time and sampling volume can be controlled through the flow meter. The air inlet bottle is used to input the air to be measured. After the air is input through the air inlet bottle, it passes through the first drying tube. The first drying tube can be used to remove the moisture in the air to avoid the interference of the moisture in the air on the subsequent sulfur isotope analysis. The air dried by the first drying tube enters the filter. The filter is used to remove the particulate matter in the air to avoid the influence of the particulate matter on the subsequent collection of sulfur dioxide samples. The air filtered by the filter enters the sulfuric acid vapor collector. A cavity for condensate to pass through is formed between the first inner tube and the first outer tube arranged on the sulfuric acid vapor collector. The condensate enters the cavity from the condensate inlet to reduce the temperature of the sulfuric acid vapor collector, so that the sulfuric acid vapor in the air condenses into liquid droplets to avoid interference with the subsequent sulfur isotope measurement of SO 2 . In addition, the condensate inlet and the condensate outlet can realize the recycling of condensate, thereby improving the condensation efficiency and ensuring the collection efficiency of sulfuric acid vapor; the barbs arranged inside the first inner tube can effectively increase the air flow path and contact area, and at the same time disrupt the gas flow, making it easier for the sulfuric acid vapor to condense on the tube wall. Subsequently, the air enters the sulfur dioxide collector. The sulfur dioxide collector is used to capture and oxidize sulfur dioxide in the air, oxidizing sulfur dioxide into sulfate ions (SO 4 2- ), to achieve rapid conversion. Subsequently, the air enters the ice bath device to remove the water vapor in the air. The ice bath device reduces the temperature to condense the water vapor in the air into liquid water and remove it to prevent the interference of water vapor. The air after passing through the ice bath device enters the second drying tube, which can remove the moisture in the air for the second time to prevent damage to the flow meter.

[0011] The collection device adopts an integrated design and integrates functions of condensation, oxidation and precipitation, simplifies the sample pretreatment process, avoids cross-contamination, improves the accuracy and efficiency of analysis. At the same time, when the collection device is used for sulfur isotope analysis with a Nano Secondary Ion Mass Spectrometer (NanoSIMS), it significantly reduces the sample quantity requirement and shortens the sampling time to the hour level, achieving short-term monitoring.

[0012] Further, a first sealing cover is provided at the top of the sulfur dioxide collector. A first intake pipe and a first outlet pipe are provided on the first sealing cover. An oxidant is provided inside the sulfur dioxide collector.

[0013] The beneficial effects of adopting the above technical solution are as follows: The first sealing cover ensures the sealing of the sulfur dioxide collector, prevents the entry of external air or impurities, thus ensuring the purity of the collected sulfur dioxide and the accuracy of analysis. The first intake pipe allows external air to enter the inside of the sulfur dioxide collector, while the first outlet pipe is used to discharge the treated gas. The oxidant provided inside the sulfur dioxide collector is used to completely oxidize sulfur dioxide in the air into sulfate ions (SO 4 2- ), realizing the rapid conversion of sulfur dioxide. It can not only effectively improve the collection efficiency of sulfur dioxide, but also avoid the fractionation phenomenon of sulfur isotopes during the sampling process, and simplifies the subsequent treatment steps, greatly improving the collection and analysis efficiency.

[0014] Further, the ice bath device includes an ice bath tank. An ice bath bottle is provided inside the ice bath tank. Glass wool is provided inside the ice bath bottle. A second sealing cover is provided at the top of the ice bath bottle. A second intake pipe and a second outlet pipe are provided at the upper end of the second sealing cover.

[0015] The beneficial effects of adopting the above technical solution are as follows: The ice bath tank is used to place ice cubes or refrigerants to lower the temperature of the ice bath bottle, which is beneficial to condensing the residual water vapor in the air. The second sealing cover at the top of the ice bath bottle ensures the sealing performance, which can prevent impurities in the external air from entering, thereby ensuring the purity of the input air and the accuracy of analysis. The glass wool provided inside the ice bath bottle can effectively reduce the heat exchange between the inside and the outside of the ice bath bottle and maintain the stability of the low-temperature environment, thus improving the condensation efficiency of water vapor.

[0016] Further, one end of the intake bottle is provided with a second intake port, and the second intake port is in a horn shape. The other end of the intake bottle is provided with a second outlet port.

[0017] The beneficial effects of adopting the above technical solution are as follows: The horn-shaped second intake port can guide the air flow into the intake bottle, and at the same time increases the contact area between the second intake port and the air flow, improving the collection amount of the sampling gas.

[0018] Further, both the first drying tube and the second drying tube include a second inner tube and a second outer tube disposed outside the second inner tube. A third air inlet pipe is provided in the middle of the second inner tube. A plurality of through holes are provided on the third air inlet pipe. The third air inlet pipe penetrates through the second outer tube. A desiccant is provided between the second inner tube and the second outer tube.

[0019] The beneficial effects of adopting the above technical solution are as follows: The first drying tube and the second drying tube adopt a double-layer structure. An accommodation cavity for accommodating the desiccant is formed between the second inner tube and the second outer tube. The third air inlet pipe ensures the smooth input of air. The plurality of through holes provided on the third air inlet pipe enable the gas to fully contact the desiccant when flowing through the drying tube, thereby ensuring the removal of moisture in the air.

[0020] Further, the air inlet bottle, the first drying tube, the filter, the sulfuric acid vapor collector, the sulfur dioxide collector, the ice bath device, the second drying tube, the flow meter and the vacuum pump are connected by conductive silica gel tubes.

[0021] The beneficial effects of adopting the above technical solution are as follows: The conductive silica gel tube has excellent elasticity and flexibility. It can not only ensure the tight connection between components, prevent gas leakage, but also withstand certain pressure and temperature changes, ensuring the stability and reliability of the sampling and analysis process.

[0022] Based on the above collection device for measuring sulfur isotope of sulfur dioxide in the atmosphere, an analysis method for measuring sulfur isotope of sulfur dioxide in the atmosphere is provided, which specifically includes the following steps: S1: Collect sulfur dioxide gas: Turn on the vacuum pump, set the flow rate of the flow meter. Outdoor air is input through the second air inlet. The input air sequentially passes through the air inlet bottle, the first drying tube, the filter, the sulfuric acid vapor collector, the sulfur dioxide collector, the ice bath device and the second drying tube, and runs for 4 - 16 h, then turn off the vacuum pump; S2: Prepare BaSO 4 precipitate: Pour the solution in the sulfur dioxide collector into a beaker, add an acidic solvent to adjust the pH, and then continuously stir and add BaCl 2 solution. After adding the BaCl 2 solution, let it stand until BaSO 4 precipitate precipitates; S3: Prepare BaSO 4 particles: Adjust the pH of the standing solution with ultrapure water. After the adjustment is completed, filter it with a gold-plated filter membrane, and wash the BaSO 4 precipitate with ultrapure water. After the filtration is completed, obtain BaSO 4 particles. Put the filter membrane with BaSO 4 particles into a drying oven for drying; S5: Analyze BaSO 4Particles: After drying the BaSO particles, analyze them using a nano-secondary ion mass spectrometer, and analyze the BaSO standard sample and the precipitated BaSO particles to determine the content of sulfur isotopes. 4 Particles, and analyze the BaSO 4 Standard sample and the precipitated BaSO 4 Particles to determine the content of sulfur isotopes.

[0023] The beneficial effects of adopting the above technical solution are as follows: In S1, by turning on the vacuum pump and setting the flow rate of the flowmeter, the gas flow rate and sampling duration during sampling can be accurately controlled, ensuring that the collected sulfur dioxide sample is representative. At the same time, through the inlet bottle, drying tube, and filter, moisture, particulate matter and other impurities in the gas can be effectively removed, improving the accuracy of subsequent analysis; In S2, sulfur dioxide is converted into stable BaSO precipitation through a chemical reaction, which is convenient for subsequent analysis and measurement. Then, by standing still, the BaSO precipitation is completely precipitated, improving the purity and quality of the precipitation; In S3, pure BaSO precipitation can be obtained through filtration and washing. The gold-plated filter membrane refers to the pre-gold-plating treatment of the non-conductive polycarbonate filter membrane to make it conductive, facilitating subsequent sulfur isotope analysis using a nano-secondary ion mass spectrometer; In S4, use a nano-secondary ion mass spectrometer to analyze the dried BaSO particles. By comparing the sulfur isotope content of the BaSO standard sample and the BaSO particles obtained by precipitation, the sulfur isotope composition of sulfur dioxide in the atmosphere can be accurately determined, and this process realizes high-precision measurement of sulfur isotopes of sulfur dioxide. 4 Precipitation, which is convenient for subsequent analysis and measurement. Then, by standing still, the BaSO 4 Precipitation completely precipitates, improving the purity and quality of the precipitation; In S3, pure BaSO 4 Precipitation can be obtained through filtration and washing. The gold-plated filter membrane refers to the pre-gold-plating treatment of the non-conductive polycarbonate filter membrane to make it conductive, facilitating subsequent sulfur isotope analysis using a nano-secondary ion mass spectrometer; In S4, use a nano-secondary ion mass spectrometer to analyze the dried BaSO 4 Particles. By comparing the BaSO 4 Standard sample and the BaSO 4 Particles obtained by precipitation, the sulfur isotope composition of sulfur dioxide in the atmosphere can be accurately determined, and this process realizes high-precision measurement of sulfur isotopes of sulfur dioxide.

[0024] Furthermore, the flow rate of the flowmeter is 0.5 - 2 L / min.

[0025] The beneficial effects of adopting the above technical solution are as follows: When the flow rate of the flowmeter is set within the range of 0.5 - 2 L / min, the flowmeter can improve the collection effect of sulfur dioxide and reduce equipment damage and maintenance costs caused by too large or too small flow rates.

[0026] Furthermore, in S2, pH < 3, and the molar concentration of the BaCl solution is 2 mol / L. 2 Solution is 2 mol / L.

[0027] The beneficial effects of adopting the above technical solution are as follows: When pH < 3, the reaction between sulfate ions (SO 4 2- ) and barium ions (Ba 2+ ) is faster and more complete. This not only facilitates the formation of BaSO 4 Precipitation, but also inhibits the reaction of other metal ions or impurities, thereby improving the BaSO 4The yield and purity of the precipitate can provide high-quality samples for subsequent isotope analysis. At the same time, during the preparation of BaSO 4 precipitate, BaCl 2 solution reacts with sulfate ions (SO 4 2- ) in the solution to form insoluble BaSO 4 precipitate. The BaCl 2 solution with a molar concentration of 2 mol / L can ensure that during the stirring process, there are sufficient barium ions (Ba 2+ ) combined with sulfate ions, thus efficiently generating BaSO 4 precipitate.

[0028] Furthermore, in S3, the gold plating layer thickness of the gold-plated filter membrane < 10 nm.

[0029] The beneficial effects of adopting the above technical solutions are as follows: The gold plating layer can increase the conductivity of the polycarbonate filter membrane, and the gold plating layer with a thickness < 10 nm can not only ensure the filtering performance of the filter membrane but also ensure that the sample will not be lost or contaminated during the filtering process.

[0030] In summary, the collection device and analysis method for measuring sulfur isotopes of sulfur dioxide in the atmosphere provided by the present invention have the following beneficial effects: (1) The collection device adopts an integrated design, reducing the operation steps and equipment, lowering the operation complexity and cost. It integrates an air inlet bottle, a first drying tube, a filter, a sulfuric acid vapor collector, a sulfur dioxide collector, an ice bath device, a second drying tube, a flow meter, and a vacuum pump, realizing the efficient collection and pretreatment of sulfur dioxide and sulfate in the atmosphere, reducing the loss of samples during the collection and transfer processes, and avoiding cross-contamination, thereby improving the accuracy and efficiency of analysis.

[0031] (2) The sulfuric acid vapor collector in the collection device increases the path length and contact area of the gas flow through the barbed structure, effectively collecting sulfuric acid vapor in the air and preventing it from interfering with the subsequent sulfur isotope measurement of sulfur dioxide.

[0032] (3) The analysis method uses a nano-secondary ion mass spectrometer (NanoSIMS) to analyze the sulfur isotopes of single-particle BaSO 4 , and the required sample amount is as low as the microgram level, significantly reducing the sample amount requirement for instrumental analysis.

[0033] (4) The analysis method uses a nuclear pore polycarbonate filter membrane with a gold plating layer thickness < 10 nm for one-step filtration, eliminating the need for complex extraction, purification, and other steps, and simplifying the pretreatment process.

[0034] (5) The analysis method can completely oxidize sulfur dioxide to sulfate ions (SO4 2- ), avoiding the sulfur isotope fractionation phenomenon caused by incomplete adsorption. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic structural diagram of the collection device in the present invention; Figure 2 It is a flow chart of sulfur isotope analysis in the present invention; Figure 3 It is a scanning electron microscope image of the sample in the embodiment of the present invention; Figure 4 In the sample obtained by NanoSIMS analysis in the embodiment of the present invention (a) 32 S and (b) 34 Content and distribution map of S; Wherein, 1, inlet gas bottle; 2, first drying tube; 3, filter; 4, sulfuric acid vapor collector; 41, first inner tube; 42, first outer tube; 43, condensate inlet; 44, condensate outlet; 45, first air inlet; 46, first air outlet; 5, sulfur dioxide collector; 51, first sealing cover; 52, first inlet pipe; 53, first outlet pipe; 6, ice bath device; 61, ice bath tank; 62, ice bath bottle; 63, glass wool; 64, second sealing cover; 65, second inlet pipe; 66, second outlet pipe; 7, second drying tube; 71, third inlet pipe. DETAILED DESCRIPTION OF THE INVENTION

[0036] The following describes the specific embodiments of the present invention to facilitate those skilled in the art of the present technology to understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific embodiments. For those of ordinary skill in the art of the present technology, as long as various changes are within the spirit and scope of the present invention defined and determined by the appended claims, these changes are obvious, and all inventions and creations using the concept of the present invention are within the scope of protection.

[0037] Example 1 As Figure 1As shown in the figure, the collection device and analysis method for measuring sulfur isotope of sulfur dioxide in the atmosphere provided by the present invention include an air inlet bottle 1, a first drying tube 2, a filter 3, a sulfuric acid vapor collector 4, a sulfur dioxide collector 5, an ice bath device 6, a second drying tube 7, a flow meter and a vacuum pump connected in sequence. Among them, the vacuum pump is used to provide a negative pressure environment to enable air to smoothly enter the device and perform subsequent collection and processing. The flow meter is used to measure and control the air flow rate entering the collection device. At the same time, the sampling time and sampling volume can be controlled through the flow meter. The air inlet bottle 1 is used to input the air to be measured. After the air is input through the air inlet bottle 1, it passes through the first drying tube 2. The first drying tube 2 can be used to remove the moisture in the air to avoid the interference of the moisture in the air on the subsequent sulfur isotope analysis. The air dried by the first drying tube 2 enters the filter 3. The filter 3 is used to remove the particulate matter in the air to avoid the influence of the particulate matter on the collection of subsequent sulfur dioxide samples. The air filtered by the filter 3 enters the sulfuric acid vapor collector 4, which can be used to collect the sulfuric acid vapor in the air to avoid the interference on the subsequent sulfur isotope measurement of sulfur dioxide. Subsequently, the air enters the sulfur dioxide collector 5. The sulfur dioxide collector 5 is used to capture and oxidize the sulfur dioxide in the air, oxidize the sulfur dioxide into sulfate ions (SO 4 2- ), to achieve rapid conversion. Subsequently, the air enters the ice bath device 6, which is used to remove the water vapor in the air. And the ice bath device 6 condenses the water vapor in the air into liquid water and removes it by reducing the temperature to prevent the interference of the water vapor. The air after passing through the ice bath device 6 enters the second drying tube 7, which can remove the moisture in the air for the second time to prevent damage to the flow meter.

[0038] As Figure 1 shown, one end of the air inlet bottle 1 is provided with a second air inlet, and the second air inlet is in a horn shape. The other end of the air inlet bottle 1 is provided with a second air outlet. The horn-shaped second air inlet can guide the air flow into the air inlet bottle 1, and at the same time increases the contact area between the second air inlet and the air flow, improving the collection amount of the sampled gas.

[0039] As Figure 1 shown, both the first drying tube 2 and the second drying tube 7 include a second inner tube and a second outer tube arranged outside the second inner tube. A third air inlet pipe 71 is arranged in the middle of the second inner tube. A number of through holes are arranged on the third air inlet pipe 71. The third air inlet pipe 71 penetrates through the second outer tube. A drying agent is arranged between the second inner tube and the second outer tube. The first drying tube 2 and the second drying tube 7 adopt a double-layer structure. A containing cavity for containing drying agents such as silica gel is formed between the second inner tube and the second outer tube. The third air inlet pipe 71 ensures the smooth input of air. The number of through holes arranged on the third air inlet pipe 71 enables the gas to fully contact with the drying agent when flowing through the drying tube, thus ensuring the removal of moisture in the air.

[0040] As Figure 1As shown, the sulfuric acid vapor collector 4 includes a first inner tube 41 and a first outer tube 42 disposed outside the first inner tube 41. One side of the upper end of the first outer tube 42 is provided with a condensate inlet 43, and one side of the lower end of the first outer tube 42 is provided with a condensate outlet 44. The other side of the upper ends of the first inner tube 41 and the first outer tube 42 is provided with a first air outlet 46, and the other side of the lower ends of the first inner tube 41 and the first outer tube 42 is provided with a first air inlet 45. Barbs are provided inside the first inner tube 41. The sulfuric acid vapor collector 4 is supported by quartz glass, and a receiving cavity for condensate to pass through is formed between the first inner tube 41 and the first outer tube 42. The condensate enters the receiving cavity from the condensate inlet 43, which is used to reduce the temperature of the sulfuric acid vapor collector 4, condense the sulfuric acid vapor in the air into liquid droplets, and avoid interference with the subsequent sulfur isotope measurement of SO 2 The sulfur isotope measurement is interfered. In addition, the condensate inlet 43 and the condensate outlet 44 enable the recycling of condensate, thereby improving the condensation efficiency and ensuring the collection efficiency of sulfuric acid vapor; the barbs provided inside the first inner tube 41 can effectively increase the flow path and contact area of the air, and at the same time disrupt the gas flow, making it easier for the sulfuric acid vapor to condense on the tube wall.

[0041] As Figure 1 shown, a first sealing cover 51 is provided at the top of the sulfur dioxide collector 5. A first intake pipe 52 and a first outlet pipe 53 are provided on the first sealing cover 51. An oxidant is provided inside the sulfur dioxide collector 5. Among them, the sulfur dioxide collector 5 is made of materials such as polytetrafluoroethylene and cannot be made of metal materials to prevent the dissolution of metal from affecting the sulfur isotope analysis structure; the first sealing cover 51 ensures the tightness of the sulfur dioxide collector 5, preventing the entry of external air or impurities, thereby ensuring the purity of the collected sulfur dioxide and the accuracy of the analysis. The first intake pipe 52 allows external air to enter the inside of the sulfur dioxide collector 5, and the first outlet pipe 53 is used to discharge the treated gas. The oxidant provided inside the sulfur dioxide collector 5 is a 100 ml solution of hydrogen peroxide (H 2 O 2 ) with a concentration of 10%. The H 2 O 2 solution ensures that sulfur dioxide is oxidized to SO 4 2- 100%, eliminating the mass difference fractionation caused by incomplete adsorption. It can not only effectively improve the collection efficiency of sulfur dioxide, but also avoid the fractionation phenomenon of sulfur isotopes during the sampling process, and also simplifies the subsequent treatment steps, greatly improving the collection and analysis efficiency.

[0042] As Figure 1As shown in the figure, the ice bath device 6 includes an ice bath tank 61. An ice bath bottle 62 is arranged inside the ice bath tank 61. Glass wool 63 is arranged inside the ice bath bottle 62. A second sealing cover 64 is arranged at the top of the ice bath bottle 62. A second air inlet pipe 65 and a second air outlet pipe 66 are arranged at the upper end of the second sealing cover 64. The ice bath tank 61 is used to place ice cubes or refrigerants to reduce the temperature of the ice bath bottle 62, which is conducive to condensing the residual water vapor in the air. The second sealing cover 64 at the top of the ice bath bottle 62 ensures the sealing performance, preventing impurities in the external air from entering, thereby ensuring the purity of the input air and the accuracy of the analysis. The glass wool 63 arranged inside the ice bath bottle 62 can effectively reduce the heat exchange between the inside and the outside of the ice bath bottle 62, maintain the stability of the low-temperature environment, and thus improve the condensation efficiency of water vapor.

[0043] The collection device adopts an integrated design, integrating the functions of condensation, oxidation, and precipitation, and uses a gold-plated filter membrane for one-step filtration. After sampling, oxidation and precipitation are directly carried out. The filter membrane after filtration is immediately used for NanoSIMS analysis, eliminating steps such as cutting the filter membrane, multiple extractions, and high-temperature conversion. The traditional method requires more than 7 steps of pretreatment (such as soaking, extraction, oxidation, precipitation, filtration, drying, and conversion of sulfur dioxide), which simplifies the sample pretreatment process, avoids cross-contamination, improves the accuracy and efficiency of the analysis. At the same time, when the collection device is used for sulfur isotope analysis with a nano-secondary ion mass spectrometer (NanoSIMS), the sample amount requirement is significantly reduced, and the sampling time is shortened to the hour level, realizing short-term monitoring.

[0044] Example 2 Based on the above collection device for measuring sulfur isotopes of sulfur dioxide in the atmosphere, as Figure 2 shown, a method for analyzing sulfur isotopes of sulfur dioxide in the atmosphere is provided, specifically including the following steps: S1: Collect sulfur dioxide gas: Turn on the vacuum pump, set the flow rate of the flow meter, and outdoor air is input through the second air inlet. The input air sequentially passes through the air inlet bottle 1, the first drying tube 2, the filter 3, the sulfuric acid vapor collector 4, the sulfur dioxide collector 5, the ice bath device 6, and the second drying tube 7, and runs for 4 - 16 hours, then turn off the vacuum pump; S2: Prepare BaSO 4 precipitate: Pour the solution in the sulfur dioxide collector 5 into a beaker, add an acidic solvent to adjust the pH, and then continuously stir and add BaCl 2 solution. After adding the BaCl 2 solution, let it stand until the BaSO 4 precipitate precipitates; S3: Prepare BaSO 4 particles: Adjust the pH of the solution after standing with ultrapure water. After the adjustment is completed, filter it with a gold-plated filter membrane, and wash the BaSO 4Precipitation, and after filtration, BaSO 4 particles are obtained. The filter membrane with BaSO 4 particles is placed in a drying oven for drying; S5: Analyze BaSO 4 particles: Use a nano-secondary ion mass spectrometer to analyze the dried BaSO 4 particles, and analyze the BaSO 4 standard sample and the BaSO 4 particles obtained by precipitation to determine the content of sulfur isotopes.

[0045] In S1, turn on the vacuum pump, flowmeter, etc., so that the sampling device starts to operate. The operation time is 4 - 16 h. By turning on the vacuum pump and setting the flow rate of the flowmeter, the gas flow rate and sampling duration during sampling can be accurately controlled, ensuring that the collected sulfur dioxide sample is representative. At the same time, through the inlet bottle 1, drying tube, and filter 3, moisture, particulate matter and other impurities in the gas can be effectively removed, improving the accuracy of subsequent analysis.

[0046] The acidic solvent added in S2 can be HCl solution, and pH < 3. The molar concentration of BaCl 2 solution is 2 mol / L. When pH < 3, the reaction between sulfate ions (SO 4 2- ) and barium ions (Ba 2+ ) is faster and more complete. This not only facilitates the formation of BaSO 4 precipitation, but also inhibits the reaction of other metal ions or impurities, thereby improving the yield and purity of BaSO 4 precipitation, providing high-quality samples for subsequent isotope analysis; at the same time, during the preparation of BaSO 4 precipitation, the BaCl 2 solution reacts with the sulfate ions (SO 4 2- ) in the solution to form insoluble BaSO 4 precipitation; the BaCl 2 solution with a molar concentration of 2 mol / L can ensure that during the stirring process, there are enough barium ions (Ba 2+ ) to combine with sulfate ions, thus efficiently generating BaSO 4 precipitation.

[0047] In S3, the pH of the standing solution is adjusted to be >5 with ultrapure water to reduce the acidity of the solution, prevent damage to the filter membrane during the subsequent filtration process, and the gold-plated layer of the gold-plated filter membrane has a thickness <10 nm, a diameter of 25 mm, and a filtration pore diameter of 0.2 μm. The gold-plated layer can increase the conductivity of the polycarbonate filter membrane, and the gold-plated layer with a thickness <10 nm can not only ensure the filtration performance of the filter membrane but also avoid the isotope fractionation caused by the incomplete contact of the air flow or the residual reagent (such as K 2 CO 3 ), and at the same time, it can also ensure that the sample will not be lost or contaminated during the filtration process. Then, the filter membrane with BaSO 4 particles is dried at 50 °C for 1 h and then stored for later use, which is convenient for subsequent sulfur isotope analysis using a nano-secondary ion mass spectrometer.

[0048] In S4, a nano-secondary ion mass spectrometer is used to analyze the dried BaSO 4 particles. By comparing the sulfur isotope content of the BaSO 4 standard sample and the precipitated BaSO 4 particles, the sulfur isotope composition of sulfur dioxide in the atmosphere can be accurately determined, and this process realizes the high-precision measurement of the sulfur isotope of sulfur dioxide.

[0049] This analysis method uses a nano-secondary ion mass spectrometer (NanoSIMS) to analyze the sulfur isotope of single-particle BaSO 4 , and the required sample amount is as low as the microgram level, significantly reducing the sample amount requirement for instrumental analysis.

[0050] Example 3 Based on the collection device in Example 1 and the analysis method in Example 2, when the concentration of SO 2 in the atmospheric environment is 4 ppb, a sample collection and analysis experiment is carried out. The sampling duration is 6 h. After precipitation filtration according to the above method process, the gold-plated polycarbonate filter membrane with BaSO 4 precipitation is first subjected to scanning electron microscopy analysis (SEM). The scanning electron microscopy images are as shown in Figure 3 . After confirming that BaSO 4 particles are obtained, the sulfur isotope situation is further analyzed by NanoSIMS. The analysis results are as shown in Figure 4 . The instrument detection signal values and their ratios of 4 sulfur isotope 32 S and 34 S of the 12 BaSO

[0051] Table 1 Instrument detection signal values and their ratios of 4 particles of the 12 analyzed BaSO 34 S / 32 S ratio

[0052] As Figure 3 , Figure 4 and Table 1 show, the sampling device and analysis method for measuring sulfur isotope of sulfur dioxide in the atmosphere provided by the present invention have high accuracy and reliability, and can be used for source analysis of SO 2 in different regions and research on its transformation process in the atmosphere, which is of great significance for quantitatively evaluating the physical and chemical effects of regional environmental sulfate aerosols. At the same time, it can also be used to monitor the pollution status of sulfur dioxide in the atmosphere, providing a scientific basis for environmental protection and pollution control.

[0053] In summary, the sampling device and analysis method for measuring sulfur isotope of sulfur dioxide in the atmosphere provided by the present invention simplify the pretreatment process, reduce operation errors, can not only significantly reduce the sample demand for instrument analysis, realize short-term pollution monitoring, but also avoid sulfur isotope fractionation and effectively remove interfering substances, ensuring the accuracy of data.

Claims

1. A collection device for measuring sulfur isotopes of sulfur dioxide in the atmosphere, characterized in that: It comprises an air inlet bottle (1), a first drying tube (2), a filter (3), a sulfuric acid vapor collector (4), a sulfur dioxide collector (5), an ice bath device (6), a second drying tube (7), a flow meter and a vacuum pump which are connected in sequence; The sulfuric acid vapor collector (4) comprises a first inner tube (41) and a first outer tube (42) arranged outside the first inner tube (41); a condensed water inlet (43) is arranged on one side of an upper end of the first outer tube (42); a condensed water outlet (44) is arranged on one side of a lower end of the first outer tube (42); a first air outlet (46) is arranged on the other side of the upper ends of the first inner tube (41) and the first outer tube (42); a first air inlet (45) is arranged on the other side of the lower ends of the first inner tube (41) and the first outer tube (42); and a barb is arranged inside the first inner tube (41).

2. The device for collecting sulfur isotopes of sulfur dioxide in the atmosphere according to claim 1, characterized in that: A first sealing cover (51) is provided at the top end of the sulfur dioxide collector (5), a first air inlet pipe (52) and a first air outlet pipe (53) are provided on the first sealing cover (51), and an oxidant is provided inside the sulfur dioxide collector (5).

3. The collecting device for measuring sulfur isotopes of sulfur dioxide in the atmosphere according to claim 1, characterized in that: The ice bath device (6) comprises an ice bath tank (61), an ice bath bottle (62) is arranged in the ice bath tank (61), glass wool (63) is arranged in the ice bath bottle (62), a second sealing cover (64) is arranged at the top end of the ice bath bottle (62), and a second air inlet pipe (65) and a second air outlet pipe (66) are arranged at the upper end of the second sealing cover (64).

4. The collecting device for measuring sulfur isotopes of sulfur dioxide in the atmosphere according to claim 1, characterized in that: One end of the gas inlet bottle (1) is provided with a second gas inlet, the second gas inlet is in a trumpet shape, and the other end of the gas inlet bottle (1) is provided with a second gas outlet.

5. The collecting device for measuring sulfur isotopes of sulfur dioxide in the atmosphere according to claim 1, characterized in that: The first drying tube (2) and the second drying tube (7) both comprise a second inner tube and a second outer tube arranged outside the second inner tube; a third air inlet tube (71) is arranged in the middle of the second inner tube; a plurality of through holes are arranged on the third air inlet tube (71); the third air inlet tube (71) penetrates the second outer tube; and a desiccant is arranged between the second inner tube and the second outer tube.

6. The collecting device for measuring sulfur isotopes of sulfur dioxide in the atmosphere according to claim 1, characterized in that: The gas inlet bottle (1), the first drying tube (2), the filter (3), the sulfuric acid vapor collector (4), the sulfur dioxide collector (5), the ice bath device (6), the second drying tube (7), the flow meter and the vacuum pump are connected via a conductive silicone tube.

7. An analytical method for measuring sulfur isotopes of sulfur dioxide in the atmosphere, based on the collection device for measuring sulfur isotopes of sulfur dioxide in the atmosphere according to any one of claims 1 to 6, characterized in that: The specific steps include: S1: Collecting sulfur dioxide gas: Turn on the vacuum pump, set the flow rate of the flow meter, input outdoor air through the second air inlet, and the input air passes through the air inlet bottle (1), the first drying tube (2), the filter (3), the sulfuric acid vapor collector (4), the sulfur dioxide collector (5), the ice bath device (6) and the second drying tube (7) in sequence. Run for 4 to 16 hours and then turn off the vacuum pump; S2: Preparation of BaSO4 precipitate: Pour the solution in the sulfur dioxide collector (5) into a beaker, add an acidic solvent to adjust the pH, then add the BaCl2 solution while stirring continuously, and let stand until BaSO4 precipitate is precipitated after adding the BaCl2 solution; S3: preparing BaSO4 particles: adjusting the pH of the solution after standing with ultrapure water, filtering with a gold-plated filter membrane, and washing the BaSO4 precipitate with ultrapure water, obtaining BaSO4 particles after filtration, and placing the filter membrane with BaSO4 particles in a drying oven for drying; S5: Analysis of BaSO4 particles: Use nano-SIMS to analyze the dried BaSO4 particles, and analyze the BaSO4 standard sample and the precipitated BaSO4 particles to determine the sulfur isotope content.

8. The analytical method for measuring sulfur isotopes of sulfur dioxide in the atmosphere according to claim 7, characterized in that: The flow rate of the flow meter is 0.5-2 L / min.

9. The analytical method for measuring sulfur isotopes of sulfur dioxide in the atmosphere according to claim 7, characterized in that: In the S2, pH is less than 3, and the molar concentration of the BaCl2 solution is 2 mol / L.

10. The analytical method for measuring sulfur isotopes of sulfur dioxide in the atmosphere according to claim 7, characterized in that: In S3, the thickness of the gold-plated layer of the gold-plated filter membrane is less than 10 nm.

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