Device for extracting trace sulfate in water, extraction method and sulfur isotope analysis method

Abstract

The present invention discloses a device for extracting trace sulfate from water, an extraction method and a sulfur isotope analysis method. The device includes a filter assembly, a waste liquid collection assembly and a vacuum assembly; the filter assembly includes at least two main pipes, a plurality of filter funnels and a plurality of filter cores, the main pipes are vertically connected with a plurality of branch pipes, and each branch pipe is provided with a switch valve; the filter core includes a shell, a core and a filter membrane, the bottom of the shell is inserted in the branch pipe, the top of the shell is connected and fixed with the filter funnel, and the filter membrane is arranged on the core; one end of the main pipe is closed, and the other end is connected with the waste liquid collection assembly, and the vacuum assembly is connected with the waste liquid collection assembly. The present invention can extract sulfate from water with extremely low sulfate content by simultaneously arranging multiple filter funnels and arranging filter membranes on the filter core, thereby reducing the sample amount of water samples, shortening the extraction time of trace sulfate in water, and the extracted barium sulfate precipitate has high purity, thereby realizing sulfur isotope analysis of extremely low sulfate content in water.

Description

Technical Field

[0001] The invention relates to the technical field of sulfate extraction, and in particular to a device for extracting trace sulfate in water, an extraction method and a sulfur isotope analysis method. Background Art

[0002] Sulfate in natural water (atmospheric water, surface water, groundwater, etc.) is affected by complex physical, chemical and biological processes. During its formation, migration, transformation and enrichment between the various spheres of the Earth system, sulfur isotope fractionation will occur, resulting in different sulfur isotope compositions (δ 34 S) characteristics. By measuring the sulfur isotope composition of sulfate in natural water, we can conduct in-depth research on the water cycle mechanism, the source and transformation of pollutants in water, the source and migration process of atmospheric sulfur dioxide, etc. However, the sulfate concentration in natural water varies widely, and the sulfate content of some water samples (such as some atmospheric water, sandstone groundwater, etc.) is extremely low (0.4-0.8 mg / L). It is difficult to collect enough samples for sulfur isotope composition analysis, which limits the application of sulfur isotopes in such water samples.

[0003] For the extraction of sulfate in natural water, when the sulfate content is high (greater than 2 mg / L), the water sample is acidified (pH value is 2), sufficient barium chloride is added to form a precipitate, and the barium sulfate precipitate is collected; when the sulfate content is low (0.8-2 mg / L), the water sample is boiled and concentrated, and sufficient barium chloride is added to form a precipitate of barium sulfate. In order to better extract sulfate from natural water, it is necessary to determine the sulfate ion concentration before extraction. At present, there is no sulfate extraction method for trace sulfate (0.4-0.8 mg / L) in water.

[0004] Moreover, in the prior art, the sulfate extraction from natural water with a high sulfate content (greater than 2 mg / L) requires a large amount of sample to be collected and a long processing time due to the large variation range of sulfate concentration (2 to several thousand mg / L) and the volume of water sample to be processed ranging from a few liters to tens of liters. In addition, due to the complex ion components in natural water, the amount of sample to be processed is large, and the purity of the collected barium sulfate precipitate is poor, which reduces the accuracy of sulfur isotope testing during mass spectrometer analysis.

[0005] During the sulfate extraction from natural water with a low sulfate content (0.8-2 mg / L), during the boiling and concentration of water samples (boiling at a high temperature greater than 100°C for a long time, 3-5 liters of water samples are concentrated to 200 ml), the long-term high temperature and the impurity precipitation formed adsorb part of the sulfate ions, etc., cause a certain degree of sulfur isotope fractionation. The collection method of barium sulfate precipitation has limitations: filtering through filter paper, putting the filter paper containing barium sulfate precipitation into a magnetic crucible, and then ashing in a muffle furnace to obtain barium sulfate; or putting the precipitation solution into a centrifuge tube, centrifuging in a high-speed centrifuge, and pouring out the supernatant to obtain barium sulfate. When the mass of barium sulfate precipitation is small (~1 mg), the particle size of the barium sulfate formed is also very small. Because part of the barium sulfate precipitation is filtered out (poured out), and part is adsorbed on the inner wall of the magnetic crucible (centrifuge tube), it is impossible to provide a sufficient amount of barium sulfate sample (greater than 0.3 mg) for instrument analysis. Summary of the invention

[0006] The purpose of the present invention is to address the above-mentioned deficiencies in the prior art and to propose a device and method for extracting trace sulfate in water, so that the sulfur isotopes of trace sulfate in water can be determined, thereby improving the analysis accuracy and test efficiency while simplifying the analysis process.

[0007] A device for extracting trace sulfate in water of the present invention comprises a filtering component, a waste liquid collection component and a vacuum component; the filtering component comprises at least two main pipelines, a plurality of filter funnels and a plurality of filter core components, the main pipeline is vertically connected with a plurality of branch pipelines, each branch pipeline is provided with a switch valve for opening or closing the branch pipeline; the filter core component comprises a shell, a core body and a filter membrane, the bottom of the shell is inserted into the branch pipeline in a one-to-one correspondence, the top of the shell is connected and fixed to the filter funnel in a one-to-one correspondence, and the filter membrane is arranged on the core body; one end of the main pipeline is closed, and the other end is connected to the waste liquid collection component, and the vacuum component is connected to the waste liquid collection component to provide negative pressure.

[0008] Furthermore, the shell includes an upper shell and a lower shell, the top of the upper shell is connected and fixed to the filter funnel, the bottom of the lower shell is inserted in the branch pipe, the core is arranged in the lower shell, the filter membrane is clamped between the upper shell and the lower shell, and the upper shell and the lower shell are connected and fixed by a connecting piece.

[0009] Furthermore, the connecting piece includes a funnel clamp.

[0010] Furthermore, the bottom of the shell is wrapped with a layer of rubber.

[0011] Furthermore, the core is a quartz sand filter element.

[0012] Furthermore, the filter membrane is a glass fiber filter membrane.

[0013] Furthermore, the waste liquid collection component includes a waste liquid barrel and a conversion connecting piece, the conversion connecting piece is arranged on the top of the waste liquid barrel, the conversion connecting piece is provided with a first connecting hole, a second connecting hole and a third connecting hole, the first connecting hole is connected to the other end of the main line, the second connecting hole is connected to the vacuum component, the third connecting hole is inserted with an exhaust air pipe, and the exhaust air pipe is provided with an exhaust air valve.

[0014] Furthermore, a waste liquid discharge switch valve is provided at the bottom of the waste liquid barrel.

[0015] Furthermore, the vacuum assembly includes an oil-free mechanical pump, and the oil-free mechanical pump is connected to the second connecting hole via a hose.

[0016] A method for extracting trace sulfate in water, using the above-mentioned device for extracting trace sulfate in water, specifically comprises the following steps:

[0017] S1. Filter water sample: filter with filter paper;

[0018] S2. Enriching water samples: The filtered water samples are adsorbed by anion resin, and after desorption, a sulfate ion concentrated solution is obtained to purify and enrich the water samples;

[0019] S3, acidified water sample: acidified with hydrochloric acid;

[0020] S4. Precipitation of water sample: Heat the water sample, add a certain concentration of barium chloride in sequence, stir rapidly, form barium sulfate precipitate and let stand overnight;

[0021] S5, precipitation filtration: close all valves of the water trace sulfate extraction device, pour the solution containing barium sulfate precipitation into the filter funnel in turn, open all switch valves, turn on the vacuum component, filter the filtrate in the funnel, close the vacuum component, and close all switch valves; repeat this step until the barium sulfate precipitation sample is completely filtered, close the vacuum component, and close all switch valves;

[0022] S6, precipitate cleaning: add deionized water to each filter funnel in turn, open all switch valves, turn on the vacuum component, filter the filtrate in the filter funnel, close the vacuum component, and close all switch valves; repeat this step several times to complete the precipitate cleaning, close the vacuum component, and close all switch valves;

[0023] S7. Take out the filter membrane: open the valve of the exhaust air pipe, and the air pressure of the whole device returns to normal atmospheric pressure; remove the funnel clamp and the filter funnel in turn, take out the filter membrane containing the barium sulfate precipitate in turn, and put them into clean glass culture dishes respectively to complete the extraction of trace sulfate in the water.

[0024] A method for analyzing sulfur isotopes of trace sulfate in water comprises the following steps: firstly using the above extraction method to extract trace sulfate in water, drying the filter membrane and cutting it into pieces, weighing it on a balance, and then wrapping it tightly with a tin cup, and determining the sulfur isotopes online using an element analyzer-gas isotope mass spectrometer.

[0025] The device for extracting trace sulfate in water of the present invention can extract trace sulfate in water by arranging a plurality of filter funnels at the same time and arranging a filter membrane on a filter element, thereby reducing the sample amount of water sample, shortening the extraction time of trace sulfate in water, and extracting barium sulfate precipitate with high purity; the same extraction method can be used for natural water samples with high sulfate content (greater than 2 mg / L) or low sulfate content (0.8-2 mg / L), and it is not necessary to measure the sulfate ion concentration before extracting sulfate; and sufficient sulfate sample amount for sulfur isotope analysis can be extracted from natural water samples with extremely low sulfate content, i.e. trace amount (0.4-0.8 mg / L); while improving the accuracy of sulfur isotope analysis, the experimental operability is also improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a schematic structural diagram of a device for extracting trace sulfate from water according to the present invention;

[0027] Figure 2 It is a schematic structural diagram of the filter element of the present invention.

[0028] 1. Filter assembly; 11. Main line; 12. Filter funnel; 13. Filter element; 131. Shell; 1311. Upper shell; 1312. Lower shell; 132. Core; 133. Filter membrane; 14. Branch line; 15. Switch valve; 2. Waste liquid collection assembly; 21. Waste liquid barrel; 22. Conversion connector; 221. First connecting hole; 222. Second connecting hole; 223. Third connecting hole; 23. Exhaust air pipe; 231. Exhaust air valve; 3. Vacuum assembly; 31. Oil-free mechanical pump; 32. Hose; 4. Connector; 41. Funnel clamp. DETAILED DESCRIPTION

[0029] The following are specific embodiments of the present invention and the accompanying drawings to further describe the technical solution of the present invention, but the present invention is not limited to these embodiments.

[0030] like Figure 1 and 2As shown, a device for extracting trace sulfate in water of the present invention comprises a filtering component 1, a waste liquid collecting component 2 and a vacuum component 3; the filtering component 1 comprises at least two main pipelines 11, a plurality of filtering funnels 12 and a plurality of filter core components 13, a plurality of branch pipelines 14 are vertically connected and arranged on the main pipeline 11, and a switch valve 15 for opening or closing the branch pipeline 14 is arranged on each branch pipeline 14; the filter core component 13 comprises a shell 131, a core body 132 and a filter membrane 133, the bottom of the shell 131 is inserted into the branch pipeline 14 one by one, the top of the shell 131 is connected and fixed to the filtering funnel 12 one by one, and the filter membrane 133 is arranged on the core body 132; one end of the main pipeline 11 is closed, and the other end is connected to the waste liquid collecting component 2, and the vacuum component 3 is connected to the waste liquid collecting component 2 to provide negative pressure.

[0031] The device for extracting trace sulfate in water of the present invention can extract sulfate in water with extremely low sulfate content (0.4-0.8 mg / L) by simultaneously arranging multiple filter funnels 12 and arranging filter membranes 133 on the filter element, thereby reducing the sample amount of the water sample, shortening the extraction time of trace sulfate in water, and the extracted barium sulfate precipitate has high purity; the same extraction method can be used for natural water samples with high sulfate content (greater than 2 mg / L) or low sulfate content (0.8-2 mg / L), and it is not necessary to measure the sulfate ion concentration before extracting sulfate; a sufficient amount of sulfate sample for sulfur isotope analysis can also be extracted from natural water samples with extremely low sulfate content (0.4-0.8 mg / L); while improving the accuracy of sulfur isotope analysis, the experimental operability is also improved.

[0032] like Figure 2 As shown, in an operative manner, the housing 131 may include an upper housing 1311 and a lower housing 1312, the top of the upper housing 1311 is connected and fixed to the filter funnel 12, the bottom of the lower housing 1312 is inserted in the branch pipe 14, the core 132 is arranged in the lower housing 1312, the filter membrane 133 is clamped between the upper housing 1311 and the lower housing 1312, and the upper housing 1311 and the lower housing 1312 are connected and fixed by a connector 4. The connector 4 may be a funnel clamp 41, and the upper housing 1311 and the lower housing 1312 are connected and fixed by the funnel clamp 41.

[0033] In order to facilitate the bottom of the shell 131 to be tightly inserted into the branch pipe 14 , the bottom of the shell 131 is wrapped with a layer of rubber.

[0034] In one practicable manner, the core 132 may be a quartz sand filter element.

[0035] In one practicable manner, the filter membrane 133 may be a glass fiber filter membrane 133 .

[0036] There are various structures of the waste liquid collection component 2. In the present embodiment, the waste liquid collection component 2 may include a waste liquid barrel 21 and a conversion connector 22. The conversion connector 22 is disposed on the top of the waste liquid barrel 21. The conversion connector 22 is provided with a first connection hole 221, a second connection hole 222 and a third connection hole 223. The first connection hole 221 is connected to the other end of the main line 11, the second connection hole 222 is connected to the vacuum component 3, and the third connection hole 223 is provided with an exhaust air pipe 23, and an exhaust air valve 231 is provided on the exhaust air pipe 23.

[0037] The conversion connector 22 may be a soft rubber column plugged into the top of the waste liquid barrel 21 .

[0038] A waste liquid discharge switch valve 15 may also be provided at the bottom of the waste liquid barrel 21 to facilitate the discharge of waste liquid. The waste liquid barrel 21 may be made of polytetrafluoroethylene and have a capacity of 50 liters.

[0039] The vacuum assembly 3 may include an oil-free mechanical pump 31 , which is connected to the second connecting hole 222 via a hose 32 to provide negative pressure for the entire extraction device and accelerate filtrate filtration. The oil-free mechanical pump 31 is provided with a pressure gauge.

[0040] Among them, in an operative manner, the filter funnel 12 can be made of quartz material, with a capacity of 200 ml, and the filter funnel 12 can be connected and fixed to the top of the filter element 13 by molten glass. The shell 131 of the filter element 13 can be made of quartz material, and the bottom of its upper shell 1311 is ground, with an outer diameter of 30 mm and an inner diameter of 20 mm (under the premise of ensuring the weight of the funnel itself and the weight of the water, the internal aperture can be reduced as much as possible). The upper ground mouth of the lower shell 1312 and the bottom ground mouth of the upper shell 1311 are fixed by a funnel clamp 41. The core 132 is placed inside the lower shell 1312. The core 132 can be a quartz cylinder (diameter 19 mm, height 3 mm). When filtering barium sulfate precipitate, a Φ25 pore size 0.22 μm glass fiber filter membrane 133 is placed on the surface of the filter element. The area of ​​the designed core 132 can be as small as possible to ensure that more barium sulfate precipitate is enriched as much as possible on the surface of the filter membrane 133 per unit area.

[0041] The main pipeline 11 can be made of stainless steel, with fixed seats at both ends, and handles on the fixed seats. One end of the main pipeline 11 is closed, and the other end is designed with a threaded interface, which is connected to the waste liquid collection component 2 through a hose 32. The branch pipeline 14 can also be made of stainless steel to ensure sufficient strength. The switch valve 15 provided on the branch pipeline 14 for opening or closing it can be a stainless steel ball valve to control the switch of the branch filtration.

[0042] A method for extracting trace sulfate in water, using the above-mentioned device for extracting trace sulfate in water, specifically comprises the following steps:

[0043] S1. Filter water sample: filter with filter paper;

[0044] S2. Enriching water samples: The filtered water samples are adsorbed by anion resin, and after desorption, a sulfate ion concentrated solution is obtained to purify and enrich the water samples;

[0045] S3, acidified water sample: acidified with hydrochloric acid;

[0046] S4. Precipitation of water sample: Heat the water sample, add a certain concentration of barium chloride in sequence, stir rapidly, form barium sulfate precipitate and let stand overnight;

[0047] S5, precipitation filtration: close all valves of the device for extracting trace sulfate from water, pour the solution containing barium sulfate precipitate into the filter funnel 12 in turn, open all switch valves 15, turn on the vacuum component 3, filter the filtrate in the funnel, close the vacuum component 3, and close all switch valves 15; repeat this step until all the barium sulfate precipitate samples are filtered, close the vacuum component 3, and close all switch valves;

[0048] S6, precipitate cleaning: add deionized water to the filter funnel 12 in turn, open all the switch valves 15, turn on the vacuum component 3, filter the filtrate in the filter funnel 12, close the vacuum component 3, and close all the switch valves 15; repeat this step several times to complete the precipitate cleaning, close the vacuum component, and close all the switch valves 15;

[0049] S7, take out the filter membrane 133: open the valve of the exhaust air pipe 23, and the air pressure of the whole device returns to normal atmospheric pressure; remove the funnel clamp 41 and the filter funnel 12 in turn, take out the filter membrane 133 containing the barium sulfate precipitate in turn, and put them into clean glass culture dishes respectively to complete the extraction of trace sulfate in water.

[0050] A method for analyzing sulfur isotopes of trace sulfate in water can first use the above extraction method to complete the extraction of trace sulfate in water, dry the filter membrane 133 and cut it into pieces, weigh it on a balance, wrap it tightly with a tin cup, and measure the sulfur isotope online by an element analyzer-gas isotope mass spectrometer. The specific operation is as follows:

[0051] (1) Water sample filtration: Filter several natural water samples (about 2 liters per sample) through filter paper with a pore size of 0.22 μm to remove solid particles in the water;

[0052] (2) Resin exchange: The water sample is adsorbed by anion resin, and after desorption, a concentrated sulfate ion solution (about 250 ml per water sample) is obtained to purify and enrich the water sample;

[0053] (3) Acidification of water samples: 6 mol / L hydrochloric acid was added to the water sample and the pH value was measured by a pH meter to be 2;

[0054] (4) Forming precipitation: Heat the water sample on a 200-degree electric heating plate, add 15 ml of 15% barium chloride, stir rapidly with a glass rod, and let stand overnight to form a barium sulfate precipitate;

[0055] The following steps (5) to (10) are completed by the trace sulfate extraction device of the present invention;

[0056] (5) Precipitation filtration: Close all valves of the trace sulfate extraction device, remove the 12 funnel clamps 41 and the filter funnel 12 in sequence, place a high-temperature burned glass fiber microfiltration membrane 133 on the surface of each core body 132, and then install the 12 filter funnels 12 with the filter element 13, and clamp the funnel clamp 41; pour 12 pieces of barium sulfate precipitate solution into the filter funnel 12 in sequence (in this embodiment, the number of filter funnels is 12), open the switch valve 15 of each branch pipeline 14, start the oil-free mechanical pump 31, and the filtrate passes through the filter membrane 133 and enters the waste liquid barrel 21. After the filtrate in the filter funnel 12 is filtered, close the switch valve 15 of each branch pipeline 14; repeat this step until all 12 pieces of barium sulfate precipitate samples are filtered, and then turn off the oil-free mechanical pump 31;

[0057] (6) Precipitate cleaning: 30 ml of deionized water is added to each of the 12 filter funnels 12 in turn, all the switch valves 15 are opened, and the oil-free mechanical pump 31 is turned on. The filtrate is filtered through the filter membrane 133 and enters the waste liquid bucket 21. After the filtrate in the filter funnel 12 is filtered, the switch valves 15 of each branch pipeline 14 are closed; this step is repeated 3 times to complete the precipitation cleaning, and the mechanical pump 31 is turned off;

[0058] (7) Removing the filter membrane 133: Open the exhaust air valve 231 of the exhaust air pipe 23, and return the air pressure of the entire device to normal atmospheric pressure; remove the 12 funnel clips 41 and the filter funnel 12 in sequence, and use tweezers to remove the filter membranes 133 containing the barium sulfate precipitate in sequence, and place them in clean glass culture dishes respectively;

[0059] (8) Waste liquid discharge: Open the waste liquid discharge switch valve 15 at the bottom of the waste liquid barrel 21 to discharge the waste liquid in the waste liquid barrel 21;

[0060] (9) Cleaning the filter funnel 12 and the filter element 13: Remove the filter funnel 12 and the filter element 13, and clean them with tap water and deionized water respectively; and install the filter funnel 12 and the filter element 13 back into the trace sulfate extraction device;

[0061] (10) Repeat steps (5) to (9) to complete the extraction of trace sulfate in all water;

[0062] (11) Precipitation drying: Place the culture dish containing the filter membrane 133 in an oven and dry it at 70° C. for 24 hours, then place it in a desiccator for later use;

[0063] (12) Sample analysis: The filter membrane 133 containing the barium sulfate precipitate was cut into pieces, weighed on a balance, and tightly wrapped in a tin cup. The sulfur isotope was determined by an elemental analyzer-gas isotope mass spectrometer (EA-IRMS).

[0064] For matters not mentioned above, the prior art applies.

[0065] Although some specific embodiments of the present invention have been described in detail through examples, those skilled in the art should understand that the above examples are for illustration only and are not intended to limit the scope of the present invention. Those skilled in the art to which the present invention belongs may make various modifications or supplements to the specific embodiments described or replace them in a similar manner, but they will not deviate from the direction of the present invention or exceed the scope defined by the attached claims. Those skilled in the art should understand that any modifications, equivalent substitutions, improvements, etc. made to the above embodiments based on the technical essence of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for extracting trace sulfate in water, characterized in that: A device for extracting trace sulfate from water is used, the device comprising a filter assembly (1), a waste liquid collection assembly (2) and a vacuum assembly (3); the filter assembly (1) comprises at least two main pipes (11), a plurality of filter funnels (12) and a plurality of filter cores (13); a plurality of branch pipes (14) are vertically connected to the main pipe (11), and each branch pipe (14) is provided with a switch valve (15) for opening or closing the branch pipe; the filter core (13) comprises a housing (1 31), a core (132) and a filter membrane (133), the bottom of the shell (131) is inserted into the branch pipeline (14) in a one-to-one correspondence, the top of the shell (131) is connected and fixed to the filter funnel (12) in a one-to-one correspondence, and the filter membrane (133) is arranged on the core (132); one end of the main pipeline (11) is closed, and the other end is connected to the waste liquid collection component (2), and the vacuum component (3) is connected to the waste liquid collection component (2) to provide negative pressure; The housing (131) comprises an upper shell (1311) and a lower shell (1312); the top of the upper shell (1311) is connected and fixed to the filter funnel (12); the bottom of the lower shell (1312) is inserted into the branch pipeline (14); the core (132) is arranged in the lower shell (1312); the filter membrane (133) is sandwiched between the upper shell (1311) and the lower shell (1312); and the upper shell (1311) and the lower shell (1312) are connected and fixed via a connecting piece (4); The connecting piece (4) comprises a funnel clamp (41); The extraction method specifically comprises the following steps: S1. Filter water sample: filter with filter paper; S2. Enriching water samples: The filtered water samples are adsorbed by anion resin, and after desorption, a sulfate ion concentrated solution is obtained to purify and enrich the water samples; S3, acidified water sample: acidified with hydrochloric acid; S4. Precipitation of water sample: Heat the water sample, add a certain concentration of barium chloride in sequence, stir rapidly, form barium sulfate precipitate and let stand overnight; S5, precipitation filtration: close all valves of the water trace sulfate extraction device, pour the solution containing barium sulfate precipitation into the filter funnel (12) in turn, open all the switch valves (15), turn on the vacuum component (3), filter the filtrate in the funnel, close the vacuum component (3), and close all the switch valves (15); repeat this step until the barium sulfate precipitation sample is completely filtered, close the vacuum component (3), and close all the switch valves (15); S6, precipitate cleaning: deionized water is added to the filter funnel (12) in turn, all the switch valves (15) are opened, the vacuum component (3) is turned on, the filtrate in the filter funnel (12) is filtered out, the vacuum component (3) is turned off, and all the switch valves (15) are turned off; this step is repeated several times to complete the precipitate cleaning, the vacuum component (3) is turned off, and all the switch valves (15) are turned off; S7, taking out the filter membrane (133): Open the valve of the exhaust air pipe (23) to return the air pressure of the entire device to normal atmospheric pressure; remove the funnel clamp (41) and the filter funnel (12) in turn, take out the filter membrane (133) containing the barium sulfate precipitate in turn, and place them in clean glass culture dishes respectively to complete the extraction of trace sulfate in water.

2. The method for extracting trace sulfate in water according to claim 1, characterized in that: The bottom of the housing (131) is wrapped with a layer of rubber.

3. The method for extracting trace sulfate in water according to claim 1, characterized in that: The core (132) is a quartz sand filter element.

4. The method for extracting trace sulfate in water according to claim 1, characterized in that: The filter membrane (133) is a glass fiber filter membrane.

5. The method for extracting trace sulfate in water according to claim 1, characterized in that: The waste liquid collection assembly (2) comprises a waste liquid barrel (21) and a conversion connection piece (22); the conversion connection piece (22) is arranged at the top of the waste liquid barrel (21); the conversion connection piece (22) is provided with a first connection hole (221), a second connection hole (222) and a third connection hole (223); the first connection hole (221) is connected to the other end of the main pipe (11); the second connection hole (222) is connected to the vacuum assembly (3); an exhaust air pipe (23) is inserted into the third connection hole (223); and an exhaust air valve (231) is provided on the exhaust air pipe (23); and a waste liquid exhaust switch valve (15) is provided at the bottom of the waste liquid barrel (21).

6. The method for extracting trace sulfate in water according to claim 1, characterized in that: The vacuum assembly (3) comprises an oil-free mechanical pump (31), and the oil-free mechanical pump (31) is connected to the second connection hole (222) via a hose (32).

7. A method for sulfur isotope analysis of trace sulfate in water, characterized in that: First, the extraction method described in claim 1 is used to extract trace sulfate in water, the filter membrane (133) is dried and cut into pieces, weighed on a balance, and then tightly wrapped in a tin cup, and the sulfur isotope is determined online by an element analyzer-gas isotope mass spectrometer.

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