A rapid pre-treatment method and sampling device for measuring carbon isotopes in water

Abstract

The present invention relates to a rapid pre-treatment method and a sampling device for measuring carbon isotopes in water in the field of carbon isotope measurement. The method comprises: (1) sealing a reaction bottle with a lid with a silica gel diaphragm, evacuating, and injecting a saturated solution of Ba(OH)2 into the bottle; (2) filling a sampling bag with groundwater for sampling, and sealing the sampling bag in water; (3) injecting an acid solution into the sampling bag, and the gas generated in the bag overflows to the upper part of the sampling bag; extracting the gas generated in the sampling bag, injecting it into the reaction bottle, and generating a precipitate; (4) freezing the reaction bottle to freeze the precipitate, freeze-drying the precipitate, and obtaining a solid powder; mixing the solid powder with Ta powder, adding it to a copper target, and then testing can be performed. The sampling method can effectively avoid contact with air during the sampling process, improves the rapidity and accuracy of extracting a small amount of carbon isotope samples from water, and is suitable for detecting carbon isotopes using an accelerator mass spectrometer.

Description

Technical Field

[0001] The invention relates to the field of carbon isotope measurement, and more particularly to a rapid pre-treatment method and a sampling device for measuring carbon isotopes in water. Background Art

[0002] Inorganic carbon in water is in the form of CO 2 , HCO 3 , H 2 CO 3 , CO 3 Form exists, 14 C is a radioactive isotope of carbon. Measuring its activity in groundwater can determine the age of groundwater. 14 The instrument for measuring C is an accelerator mass spectrometer. The instrument requires a small amount of sample, and the mass of C required is 1 to 5 mg. However, in the pretreatment process, water samples are still collected in the field to convert inorganic carbon in the water into CO 2 , using cobalt catalyst for hydrogen reduction, making graphite target and putting it into AMS instrument to complete the test. This method is time-consuming to operate, and especially requires a set of simple pre-treatment device and method for pre-treatment. Summary of the invention

[0003] In order to solve the above problems existing in the prior art, the present invention proposes a rapid pre-treatment method for measuring carbon isotopes in water, and specifically relates to a rapid pre-treatment method for measuring carbon isotopes in water and a sampling device.

[0004] One of the purposes of the present invention is to provide a rapid pre-treatment method for measuring carbon isotopes in water, which may include the following steps:

[0005] (1) The reaction bottle was sealed with a lid with a silicone septum, and the vacuum was evacuated to remove Ba(OH) 2 The saturated solution was injected into the reaction bottle for later use;

[0006] (2) Filling the sampling bag with groundwater for sampling and sealing the sampling bag in the water;

[0007] (3) injecting an acid solution into a sampling bag, and causing gas to overflow from the sampling bag to the upper portion of the sampling bag; extracting the gas generated from the sampling bag and injecting it into a reaction bottle to generate a precipitate;

[0008] (4) Freeze the reaction bottle to freeze the precipitate, freeze-dry the precipitate to obtain a solid powder; mix the solid powder with Ta powder, add it to the copper target, and then perform the test.

[0009] Preferably,

[0010] The step (1) may include the following steps:

[0011] Place the empty reaction bottle in a flushing bag filled with inert gas, flush the bottle with inert gas, seal the reaction bottle with a lid with a silicone diaphragm, evacuate to below 200 Pa, and inject 1-3 mL of Ba(OH) 2 The saturated solution is injected into a reaction bottle; the reaction bottle is a glass bottle, preferably a round-bottom glass bottle (5 ml).

[0012] Step (1) can be completed in the laboratory and does not need to be taken to the field.

[0013] in,

[0014] The Ba(OH) 2 The saturated solution can be prepared by a method comprising the following steps:

[0015] Add deionized water into the glass bottle, then add Ba(OH) 2 8H 2 O, to make saturated Ba(OH) 2 Solution.

[0016] The step (2) may include the following steps:

[0017] Put the sampling bag and the sampling bag cover into a sampling bucket; preferably, the height of the sampling bucket is greater than the length of the sampling bag;

[0018] The groundwater for sampling is passed through the water pipe into the sampling bag. When the sampling bag is full of water, the water flows out of the sampling bag and enters the sampling bucket and overflows (preferably after 3 minutes of overflow). Then, the water pipe is taken out and the sampling bag is pressed underwater to make the water in the bag flow out of 8-12% of the capacity of the sampling bag to reserve space for the collection of CO dissolved in the water. 2 The sampling bag is sealed underwater with a sampling bag cover, and then the sampling bag is taken out. The sampling bag is deformable, which is convenient for adjusting the amount of water in the bag without letting in air, thereby avoiding air pollution.

[0019] Wherein, the capacity of the sampling bag can be 500-1000mL.

[0020] The step (3) may include the following steps:

[0021] Use a second syringe to inject 5-10 mL of acid solution into the sampling bag, and the gas generated in the sampling bag overflows to the upper part of the sampling bag; use a third syringe to extract the gas generated in the sampling bag and inject it into the saturated Ba(OH) 2 The solution is placed in a reaction bottle and shaken to mix well to form a precipitate;

[0022] The concentration of the acid solution may be 50 to 85 wt %;

[0023] The acid may be selected from at least one of hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid; phosphoric acid is preferred;

[0024] Preferably, the first, second and third syringes are cleaned with inert gas more than three times before use.

[0025] In the step (4):

[0026] The Ta powder particle size may be 325 mesh;

[0027] The mass ratio of the solid powder to the Ta powder may be 1:(1-2).

[0028] The second object of the present invention is to provide a sampling device for the rapid pre-treatment method for measuring carbon isotopes in water, which may include:

[0029] Reaction bottle, can be placed in the flushing bag; the volume can be 5mL;

[0030] A lid with a silicone septum for sealing the reaction bottle;

[0031] Flushing bag, used to contain inert gas; the material can be polyethylene;

[0032] A sampling bag, used to contain groundwater for sampling, capable of being placed in the sampling bucket;

[0033] Sampling bag cover;

[0034] A sampling bucket, used to place the sampling bag and contain groundwater for sampling; the material of the sampling bucket may be high borosilicate glass;

[0035] A water guide tube, which can be inserted into the sampling bag and is used to guide groundwater into the sampling bag;

[0036] Three syringes, including a first syringe, a second syringe, and a third syringe, wherein the first syringe is used to be inserted into the reaction bottle through the cover with the silicone diaphragm; the second syringe and the third syringe are used to be inserted into the sampling bag through the cover of the sampling bag;

[0037] Preferably, the specification of the first syringe may be 2-5 mL; the specification of the second syringe may be 5-10 mL; the specification of the third syringe may be 20-50 mL.

[0038] In specific use, the sampling device may also include:

[0039] Ba(OH) 2 Solution bottle for saturated Ba(OH) 2 Solution; specifically, it can be a glass bottle;

[0040] A test tube, used to contain the mixture of the solid powder and Ta powder; the material may be high borosilicate;

[0041] Glass rod, used to mix solid powder with Ta powder.

[0042] Preferably,

[0043] The lid with the silicone diaphragm and the reaction bottle have threads that match each other;

[0044] The sampling bag and the sampling bag cover have mutually matching threads, and the sampling bag cover has a silicone diaphragm;

[0045] The reaction bottle is a glass bottle, preferably a round-bottom glass bottle.

[0046] When the sampling method described in this application is used, the amount of water taken can be determined according to actual needs, and the volume of the reaction bottle and sampling bag, the specifications of the syringe and needle, and the amount of Ba(OH) injected can be determined accordingly. 2 The amount of solution and acid solution.

[0047] Effects of the method of the present invention:

[0048] The sampling method can effectively avoid contact with air during the sampling process, improves the rapidity and accuracy of extracting a small amount of carbon isotope samples from water, is suitable for detecting carbon isotopes using an accelerator mass spectrometer, requires less material, reduces the process of hydrogen reduction of cobalt catalyst to produce graphite, is easy to operate, and is convenient to carry and operate in the field. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 For the preparation of saturated Ba(OH) in step (1) of Example 1 2 Schematic diagram of the operation of the solution and the treatment reaction bottle;

[0050] Figure 2 The schematic diagram of the operation of taking water samples in step (2) and generating precipitate in step (3) in Example 1;

[0051] Figure 3 Schematic diagram of the operation of mixing solid powder and Ta powder to prepare a copper target in step (4) of Example 1.

[0052] Explanation of the reference numerals: 11 - glass bottle, 12 - flushing bag, 13 - round-bottom glass bottle, 14 - threaded cap with silicone diaphragm, 15 - air tube, 16 - first syringe, 21 - sampling barrel, 22 - sampling bag, 23 - water tube, 24 - sampling bag cover, 25 - second syringe, 26 - third syringe, 31 - glass test tube, 32 - glass rod, 33 - copper target.

[0053] Figure 4BaCO 3 Test results of samples mixed with solid powder and Ta powder in different mass ratios.

[0054] Among them, the vertical axis is: 12 C 3+ Current value (unit: μA); horizontal axis: time (unit: seconds). DETAILED DESCRIPTION

[0055] The present invention is described in detail below in conjunction with specific embodiments. It is necessary to point out that the following embodiments are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made to the present invention by those skilled in the art based on the contents of the present invention still fall within the scope of protection of the present invention.

[0056] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0057] The raw materials used in the examples are all commercially available.

[0058] Example 1

[0059] The rapid pre-treatment method for measuring carbon isotopes in water according to the present application comprises the following steps:

[0060] (1) Preparation of Ba(OH) 2 Saturated solution: Add 80 mL of deionized water to a 100 mL glass bottle 11, then add 5 g of Ba(OH) 2 8H 2 O, to form saturated Ba(OH) 2 Solution, set aside; select a round-bottom glass bottle 13 with a volume of 5mL as a reaction bottle, put it in a flushing bag 12 with a volume of 5L filled with argon, put the argon gas guide tube 15 into the round-bottom glass bottle 13, flush the bottle with argon for 3 times, seal it with a threaded cap 14 with a silicone diaphragm, and then evacuate the round-bottom glass bottle 13 to below 200Pa, and then use a 5mL first syringe 16 (washed with argon 3 times before use) to absorb the saturated Ba(OH) in the glass bottle 11 2 2 mL of the solution was injected into a round-bottom glass bottle 13.

[0061] (2) Place a sampling bag 22 with a volume of 1 L and a sampling bag cover (a suitable threaded cover with a silicone diaphragm) 24 into a sampling bucket 21 (a cylindrical small water bucket with a diameter of 230 cm, a height of 20 cm, and a material of high borosilicate glass). Insert one end of the water pipe 23 into the bottom of the sampling bag 22 and connect the other end to a water source. Groundwater enters the sampling bag 22. When the sampling bag 22 is full of water, water flows out of the sampling bag 22 into the sampling bucket 21 until the water in the sampling bucket 21 is full and overflows. After 3 minutes, unplug the water pipe 23, press the sampling bag 22 underwater, and let about 100 mL of water flow out of the bag. Seal the sampling bag 22 underwater with the sampling bag cover 24, take out the sampling bag 22, and pour out the water in the sampling bucket 21.

[0062] (3) The second syringe 25 with a 10 mL specification was cleaned with argon gas three times before use. 5 mL of 85% concentrated phosphoric acid was drawn into the second syringe 25 and injected into the sampling bag 22. The concentrated phosphoric acid made the HCO in the groundwater 3 and CO 3 The generated gas overflows from the water to the upper part of the sampling bag 22. The third syringe 26 of 50 mL specification is purged with argon gas three times before use, and then the third syringe 26 is used to extract the CO in the upper part of the sampling bag 22. 2 The gas was rapidly injected into a saturated Ba(OH) 2 The solution is placed in a round-bottom glass bottle 13. The round-bottom glass bottle 13 is shaken to generate BaCO in the liquid. 3 precipitation.

[0063] (4) Place the round-bottomed glass bottle 13 in a refrigerator and freeze for 24 hours. Then open the threaded cap 14 with the silicone diaphragm and quickly place it in a freeze dryer to dry until it is completely dried to form BaCO 3 Solid powder. Prepare 325 mesh Ta powder with a purity of 99.9%, BaCO 3 Solid powder and Ta powder are placed in a glass test tube 31 (inner diameter 0.8 cm, length 10 cm, high borosilicate material) at a mass ratio of 1:2, mixed evenly with a glass rod 32, and then the evenly mixed powder is added to the center hole of the copper target 33 and compacted. After the pretreatment is completed, it can be put into the machine for testing.

[0064] Example 2

[0065] About BaCO 3 Screening of the mass ratio of solid powder to Ta powder:

[0066] Prepare BaCO according to the method of Example 1 3 Solid powder. Take BaCO 3 The solid powder and 325 mesh Ta powder (purity 99.9%) were divided into 4 parts, and BaCO 3Solid powder and Ta powder were placed in glass test tubes at a mass ratio of 1:0.5, 1:1, 1:2, and 1:3, respectively, and mixed evenly with a glass rod. The mixed powder was then added to the center hole of the copper target and pounded. After the pretreatment was completed, the mixed powder in the center hole of the copper target was bombarded with a cesium ion beam on a 5MV accelerator mass spectrometer to make the powder 12 C becomes charged 12 C 3+ , it was found through experiments that BaCO 3 When the mass ratio of solid powder to Ta powder is 1:(1~2) 12 C 3+ The current generated is the highest (see Figure 4 ), that is, Ta is most efficient in the measurement process, which best represents this ratio.

Claims

1. A rapid pretreatment method for measuring carbon isotopes in water, characterized in that The following steps are involved: (1) Seal the reaction bottle with a lid with a silicone septum, evacuate the bottle, and inject the saturated Ba(OH)2 solution into the reaction bottle for later use; (2) Fill the sampling bag with groundwater for sampling and seal the sampling bag in the water; (3) injecting an acid solution into a sampling bag, causing gas to overflow from the sampling bag to the upper portion of the sampling bag; extracting the gas generated from the sampling bag and injecting it into a reaction bottle to generate a precipitate; (4) Freezing the reaction bottle to freeze the precipitate, freeze-drying the precipitate to obtain a solid powder; mixing the solid powder with Ta powder, adding it to a copper target, and testing; The step (1) comprises the following steps: Place the reaction bottle in a flushing bag filled with inert gas, flush the bottle with inert gas, seal the reaction bottle with a lid with a silicone diaphragm, evacuate to below 200 Pa, and inject 1-3 mL of saturated Ba(OH)2 solution into the reaction bottle with a first syringe; The step (2) comprises the following steps: Put the sampling bag and the sampling bag cover into the sampling bucket; The groundwater used for sampling enters the sampling bag through the water pipe. When the sampling bag is full of water, the water flows out of the sampling bag, enters the sampling bucket and overflows. Then, the water pipe is taken out, and the sampling bag is pressed underwater to make 8-12% of the water in the bag flow out. The sampling bag is sealed underwater with the sampling bag cover, and then the sampling bag is taken out.

2. The rapid pre-treatment method for measuring carbon isotopes in water according to claim 1, characterized in that: The capacity of the sampling bag is 500~1000mL.

3. The rapid pre-treatment method for measuring carbon isotopes in water according to claim 1, characterized in that: The step (3) comprises the following steps: Use a second syringe to inject the acid solution into the sampling bag, and the gas generated in the sampling bag overflows to the upper part of the sampling bag; use a third syringe to extract the gas generated in the sampling bag, inject it into the reaction bottle containing the saturated Ba(OH)2 solution, shake and mix, and generate a precipitate.

4. The rapid pre-treatment method for measuring carbon isotopes in water according to claim 3, characterized in that: The amount of the acid solution is 5-10 mL; The acid is selected from at least one of hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid; The concentration of the acid solution is 50-85%.

5. The rapid pre-treatment method for measuring carbon isotopes in water according to claim 4, characterized in that: The acid is selected from phosphoric acid.

6. The rapid pre-treatment method for measuring carbon isotopes in water according to claim 3, characterized in that: The first syringe, the second syringe and the third syringe were all cleaned with inert gas for more than three times before use.

7. The rapid pre-treatment method for measuring carbon isotopes in water according to claim 1, characterized in that: In step (4): The Ta powder particle size is 325 mesh; The mass ratio of the solid powder to the Ta powder is 1:(1~2).

8. The sampling device for the rapid pre-treatment method for measuring carbon isotopes in water according to any one of claims 1 to 7, characterized in that include: Reaction bottle, which can be placed in the flushing bag; A lid with a silicone septum for sealing the reaction bottle; flush bag, to contain the inert gas; A sampling bag, used to contain groundwater for sampling, capable of being placed in the sampling bucket; A sampling bucket, used to place the sampling bag and contain the groundwater for sampling; A water guide tube, which can be inserted into the sampling bag and is used to guide groundwater into the sampling bag; Three syringes include a first syringe, a second syringe and a third syringe. The first syringe is used to be inserted into a reaction bottle through the cover with a silicone diaphragm; the second syringe and the third syringe are used to be inserted into the sampling bag through the cover of the sampling bag.

9. The sampling device for the rapid pre-treatment method for measuring carbon isotopes in water according to claim 8, characterized in that: The specification of the first syringe is 2~5mL; The specification of the second syringe is 5-10mL; The specification of the third syringe is 20-50mL.

10. The sampling device for the rapid pre-treatment method for measuring carbon isotopes in water according to claim 8, characterized in that: The lid with the silicone diaphragm and the reaction bottle have threads that match each other; The sampling bag and the sampling bag cover have mutually matching threads, and the sampling bag cover has a silicone diaphragm; The reaction bottle is a glass bottle.

11. The sampling device for the rapid pre-treatment method for measuring carbon isotopes in water according to claim 10, characterized in that: The reaction bottle is a round-bottom glass bottle.

Images