A method and kit for detecting co2 gas concentration

Abstract

The application discloses a method and a kit for detecting CO2 gas concentration and belongs to the technical field of detection. The method for detecting CO2 gas concentration adopts a cobalt nitrate complex to detect the CO2 gas concentration, and the method comprises the following steps: S1, dissolving the cobalt nitrate complex in a solvent to prepare a cobalt nitrate complex solution; S2, adding hydrogen peroxide, triethylamine and a detected gas into the cobalt nitrate complex solution obtained in the step S1 in a detection environment of-78 DEG C to 35 DEG C, the adding sequence of the three has no sequence, and the container is shaken; if the color of the solution changes from green to blue, then the detected gas contains CO2 with a concentration greater than 10%; and if the color of the solution has no change within 60 min, then the concentration of CO2 in the detected gas is less than 10%. In the method for detecting CO2 gas concentration, the color change of the detection liquid is obvious, the color changes from green to blue, and the response speed is fast.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of detection, in particular to a method and a kit for detecting CO2 gas concentration in a low-temperature environment. BACKGROUND

[0002] CO2 is widely used in agricultural product preservation, agricultural production, medical treatment, refrigeration and many other scenes, and in these application scenarios, it is necessary to quickly detect the concentration of CO2 in the environment.

[0003] At present, the detection methods of carbon dioxide can be divided into the following categories according to different application scenarios and requirements: physical optical analysis method, chemical analysis method, and electrochemical sensor method.

[0004] The physical optical analysis method includes non-dispersive infrared absorption method (NDIR) and Fourier transform infrared spectroscopy method (FTIR). These two methods utilize the characteristics of carbon dioxide absorbing infrared rays of specific wavelengths, and determine the concentration of carbon dioxide by measuring the degree of absorption of infrared rays, which has the characteristics of high resolution and high sensitivity, but the device structure is relatively complex and the equipment cost is high. The chemical analysis method uses a specific chemical absorbent (such as sodium hydroxide solution) to absorb carbon dioxide, and calculates the concentration of carbon dioxide by measuring the change in gas volume before and after absorption, which is relatively simple to operate, but is not suitable for on-site rapid detection. The electrochemical sensor method measures the concentration of carbon dioxide by detecting the electrochemical reaction between carbon dioxide and electrolyte, but an electrochemical device needs to be added to the equipment, and the system structure is relatively complex and the cost is high.

[0005] In the chemical analysis method, for example, the phenolphthalein reagent detection method has a slow response speed in a low-temperature environment; in the lime water detection method, the solvent water will freeze in a low-temperature environment. In the infrared spectroscopy detection method and the mass spectrometry detection method, the electrochemical device increases the complexity of the detection system and some environments do not allow the use of electric equipment.

[0006] The above carbon dioxide detection methods have great deficiencies in the convenience of instant use, and therefore a method for quickly detecting the concentration of CO2 gas is needed. SUMMARY

[0007] To solve the above technical problems, the present application provides a method for detecting the concentration of CO2 gas by using a cobalt nitrate complex. The color change of the detection system of the CO2 gas detection method in the present application is obvious, from green to blue, and the response speed is fast.

[0008] The present application also provides a kit for detecting the concentration of CO2 gas, which has a simple structure, a small volume, is convenient to carry, has a low cost, is easy to operate, and is completely not limited by the humidity in the environment.

[0009] To achieve the above object, the present application adopts the following technical solutions:

[0010] A method for detecting CO2 gas concentration, which adopts a cobalt nitrate complex to detect CO2 gas concentration, and comprises the following steps:

[0011] S1: dissolving the cobalt nitrate complex in a solvent to prepare a cobalt nitrate complex solution;

[0012] S2: adding hydrogen peroxide, triethylamine and the detected gas in the cobalt nitrate complex solution obtained in step S1, and there is no sequence for the addition of the three, and the container is shaken; if the color of the solution changes from green to blue, then the detected gas contains CO2 with a concentration greater than 10%; if the color of the solution does not change within 60 min, then the concentration of CO2 in the detected gas is less than 10%.

[0013] In step S2, if the color of the solution changes from green to blue instantaneously (≤2s), then the detected gas contains CO2 with a concentration greater than 20%; if the color of the solution slowly changes to blue within 60 min, then the concentration of CO2 in the detected gas is 10%-20%; if the color of the solution does not change within 60 min, then the concentration of CO2 in the detected gas is less than 10%.

[0014] The color response speed of the method for detecting the concentration of carbon dioxide is only related to the concentration of CO2 gas in the detected environment, and is not related to the temperature of the detected environment.

[0015] In step S1, the molecular structure of the cobalt nitrate complex is:

[0016] .

[0017] In step S2, the structure of the color-producing ion of the green solution is:

[0018] ;

[0019] The structure of the color-producing ion of the blue solution in step S2 is:

[0020] .

[0021] In step S1, the molar concentration of the cobalt nitrate complex solution is ≥0.001 mol / L.

[0022] In step S1, the solvent is one of acetonitrile, trifluoroethanol, tetrahydrofuran, methanol, N,N-dimethylformamide, or a mixed solvent of the above solvents.

[0023] The detection CO2 gas concentration method has a use temperature of-78℃ to 35℃.

[0024] The molar ratio of the hydrogen peroxide to the cobalt nitrate complex is greater than or equal to 1:1, and the molar ratio of the triethylamine to the cobalt nitrate complex is greater than or equal to 0.5:1.

[0025] A kit for detecting CO2 gas concentration, the kit comprising a cobalt nitrate complex, a solvent, hydrogen peroxide and triethylamine, wherein the cobalt nitrate complex forms a cobalt nitrate complex solution with the solvent, the molar concentration of the cobalt nitrate complex solution is greater than or equal to 0.001 mol / L, the molar ratio of the hydrogen peroxide to the cobalt nitrate complex is greater than or equal to 1:1, and the molar ratio of the triethylamine to the cobalt nitrate complex is greater than or equal to 0.5:1.

[0026] The kit has a storage temperature of less than or equal to-4℃.

[0027] The present application has the following advantages:

[0028] (1) The color of the detection liquid in the method for detecting CO2 gas concentration changes obviously from green to blue, and the response speed is fast.

[0029] (2) The method for detecting CO2 gas concentration can be used under low temperature conditions, especially under low temperature conditions of-78℃ to-20℃.

[0030] (3) The kit for detecting CO2 gas concentration has simple structure, small volume, low cost, simple operation, and is not limited by the humidity in the environment. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 The mass spectrum analysis diagram of the reaction product of the method for detecting CO2 gas concentration of embodiment 1 of the present application. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application is further described in detail below in combination with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application. In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as they do not conflict with each other.

[0033] A method for detecting CO2 gas concentration, which detects CO2 gas concentration by using a cobalt nitrate complex, the method for detecting CO2 gas concentration comprising the following steps:

[0034] S1: dissolving the cobalt nitrate complex in a solvent to prepare a cobalt nitrate complex solution;

[0035] S2: adding hydrogen peroxide, triethylamine and the detected gas into the cobalt nitrate complex solution obtained in step S1, the adding sequence of the three has no priority, shaking the container; if the color of the solution changes from green to blue, then the detected gas contains CO2 with a concentration greater than 10%; if the color of the solution has no change within 60 minutes, then the concentration of CO2 in the detected gas is less than 10%.

[0036] Specifically, the following reactions occur in step S2:

[0037] The hydrogen peroxide and triethylamine are added into the cobalt nitrate complex solution, and a green solution is generated by the reaction, and the reaction formula is as follows:

[0038] ;

[0039] Among them, [Co(TBDAP)(O2)](NO3) is a color-producing ion of the green solution.

[0040] The in-situ reaction of CO2 and [Co(TBDAP)(O2)](NO3) is as follows:

[0041] ;

[0042] Among them, [Co(TBDAP)(O-CO2)]NO3 and [Co(TBDAP)(O2-CO2)]NO3 are color-producing ions of the blue solution.

[0043] Example 1

[0044] A method for detecting the concentration of carbon dioxide, which uses cobalt nitrate complex as a detection reagent, the method for detecting the concentration of carbon dioxide comprises the following steps:

[0045] S1: Under the condition of 0℃, cobalt nitrate complex is prepared into an ethyl cyanide cobalt nitrate complex solution with a concentration of 0.015 mol / L. Specifically, 23.4 mg (0.046 mmol) of species 1 ([Co(TBDAP)(NO3)(H2O)](NO3)) is taken into a Xilei test tube, 3 mL of ethyl cyanide is added under the condition of 0℃, and stirring is performed for 10 minutes to obtain an ethyl cyanide cobalt nitrate complex solution with a mass-volume concentration of 7.8 mg / mL. The ethyl cyanide cobalt nitrate complex solution is pink.

[0046] S2: 0.092 mmol of 30% mass fraction hydrogen peroxide aqueous solution and 0.046 mmol of triethylamine were added into the acetonitrile cobalt nitrate complex solution obtained in step S1, and a green solution was generated; specifically, 14 uL of 30% mass fraction hydrogen peroxide aqueous solution (molar concentration: 9.78 mol / L) and 14 uL of triethylamine were added into the acetonitrile cobalt nitrate complex solution obtained in step S1, and a green solution of product 4 ([Co(TBDAP)(O2)](NO3)) was generated.

[0047] The reaction equation of step S2 is as follows:

[0048] .

[0049] S3: The detected gas was introduced into the green solution obtained in step S2 at -20°C, or the green solution obtained in step S2 was injected into a container in which the detected gas existed and was shaken; if the color of the solution changed from green to blue, then the concentration of carbon dioxide in the detected gas was greater than 10%; if the color of the solution did not change within 60 min, then the concentration of carbon dioxide in the detected gas was greater than 10%.

[0050] The reaction of step S3 is as follows:

[0051] .

[0052] Figure 1 The mass spectrum analysis diagram of the reaction product of the method for detecting the concentration of CO2 gas of embodiment 1 of the present application. See Figure 1 The blue solution was subjected to high-resolution mass spectrum detection analysis and chemical reaction eqn 3 was subjected to calculation chemical simulation modeling, and the molecular structures of species 5 and species 6 were confirmed. The product separation was performed on the deep blue solution, and it was determined that the coloring molecules therein were species 5 ([Co(TBDAP)(O-CO2)]NO3) and species 6 ([Co(TBDAP)(O2-CO2)]NO3).

[0053] The preparation method of species 1 ([Co(TBDAP)(NO3)(H2O)](NO3)) is as follows:

[0054] Take 10 mL of a three-necked round bottom flask, add 3 mL of CH3CN and 3 mL of CHCl3 to the flask, and purge with argon for 10 minutes. Add Co(NO3)2(0.146 g, 0.50 mmol) and TBDAP (0.176 g, 0.50 mmol) to the reaction solution, and stir at room temperature for 12 hours. Place the flask on a wooden support, add Et2O (40 mL) to the solution, and precipitate the pink solid after ultrasonic treatment. Take a Buchner funnel and filter bottle, and perform vacuum filtration under reduced pressure, and wash with Et2O. Perform vacuum drying in a vacuum oven for 8 hours to obtain a pink solid of species 1 ([Co(TBDAP)(NO3)(H2O)](NO3)), with a yield of 94% (0.2610 g).

[0055] wherein TBDAP (N- N -di-tert-butyl-2,11-diaza 3.3(2,6)-pyridophenanthroline) is prepared as follows:

[0056] (I) Dissolve tert-butylamine (23.4 g, 320 mmol) and 2,6-bis(chloromethyl)pyridine (1.41 g, 8.01 mmol) in acetonitrile (32 mL), add saturated K2CO3 aqueous solution (20 mL), and stir at 50°C in air for 6 hours. After the reaction is completed, cool to room temperature, and remove the solvent under reduced pressure. Extract with diethyl ether (about 50 mL x 3), dry with a mixture of MgSO4 and K2CO3, take the organic layer, filter, and spin dry under reduced pressure to obtain colorless oily liquid product 3 (1.95 g, 98%). Perform nuclear magnetic hydrogen spectrum and carbon spectrum characterization of product 3 using deuterated chloroform:

[0057] 1 H NMR (400 MHz, CDCl3), δ(ppm): 7.55 (t,J HH =7.5 Hz, p-Hp y 1H),7.16 (d,J HH = 7.5 Hz, m-H Py ,2H), 3.85 (s, 4H), 1.18 (s, 18H, tBu). 13 C{ 1 H} NMR (100 MHz,CDCl3), δ(ppm): 159.9 (o-Cp y ), 136.9 (p-Cp y ),120.3 (m-Cp y ),50.6 (-CH2-),48.6(CCH3),29.3 (CH3)。

[0058] (II) 2,6-di-tert-butyl-4-methylpyridine (1.50 g, 6.00 mmol), 2,6-di(chloromethyl)pyridine (1.06 g, 6.02 mmol), potassium iodide (500 mg, 3.01 mmol) and potassium carbonate (8.30 g, 60.1 mmol) were dissolved in 210 mL of acetonitrile and stirred at 80 °C under air for 16 hours. After removal of the solvent under reduced pressure, 150 mL of toluene was added. The mixture was stirred at 80 °C for 30 minutes to dissolve completely. The hot toluene mixture was filtered to remove inorganic salts. The toluene filtrate was concentrated under reduced pressure, then 150 mL of ethanol was added and stirred at 70 °C for 30 minutes to dissolve the target product. After cooling to room temperature, the mixture was filtered to remove insoluble by-products and the filtrate was concentrated under reduced pressure. The mixture was added to THF (30 mL) and stirred at 60 °C for 30 minutes to dissolve the by-products, then left at room temperature overnight. The white precipitate was collected by filtration, washed with a small amount of THF and dried under vacuum to obtain a white powder. The THF filtrate was evaporated and the same purification process was carried out using ethanol (30 mL) and THF (8 mL) to obtain a white solid product TBDAP (827 mg, 39%). The product TBDAP was characterized by nuclear magnetic hydrogen and carbon spectroscopy using deuterated chloroform:

[0059] 1 H NMR (400 MHz, CDCl3), δ(ppm): 7.07 (t,J HH =7.6 Hz, p-Hp y 2H),6.72 (d,J HH = 7.6 Hz, m-H Py ,4H), 3.97 (s, 8H), 1.32 (s, 18H, tBu). 13 C{ 1 H} NMR (100 MHz,CDCl3), δ(ppm): 159.5 (o-Cp y ), 135.3 (p-Cp y ),122.0 (m-Cp y ),57.8(-CH2-),56.0(CCH3),27.8 (CH3)。

[0060] The preparation reaction formula of TBDAP is as follows:

[0061] .

[0062] Example 2

[0063] A method for detecting carbon dioxide concentration, which adopts a cobalt nitrate complex solution as a detection reagent, and the method for detecting carbon dioxide concentration comprises the following steps:

[0064] S1: under the condition of 0℃, a cobalt nitrate complex is prepared into an acetonitrile cobalt nitrate complex solution with a concentration of 0.001 mol / L;

[0065] S2: 0.046 mmol of a 30% mass fraction hydrogen peroxide aqueous solution and 0.023 mmol of triethylamine are added into the acetonitrile cobalt nitrate complex solution obtained in step S1, and a detected gas (the adding sequence of hydrogen peroxide, triethylamine and the detected gas is not limited), if the color of the solution changes from green to blue instantaneously (≤2 s), then the detected gas contains carbon dioxide with a concentration greater than 20%; if the color of the solution changes to blue slowly within 60 min, then the concentration of carbon dioxide in the detected gas is 10%-20%; if the color of the solution does not change within 60 min, then the concentration of carbon dioxide in the detected gas is less than 10%.

[0066] Example 3

[0067] This example is used to evaluate the adsorption effect of carbon dioxide adsorption material on carbon dioxide.

[0068] Specifically, the detected gas is the gas after being adsorbed by the carbon dioxide adsorption material, the solution obtained in step S1, hydrogen peroxide and triethylamine are injected into the container containing the detected gas and shaken, or the detected gas, hydrogen peroxide and triethylamine are added into the solution obtained in step S1 and shaken, if the color of the solution changes from green to blue instantaneously (≤2 s), then the detected gas contains carbon dioxide with a concentration greater than 20%; if the color of the solution changes to blue slowly within 60 min, then the concentration of carbon dioxide in the detected gas is 10%-20%; if the color of the solution does not change within 60 min, then the concentration of carbon dioxide in the detected gas is less than 10%. This method can quickly evaluate the adsorption effect of carbon dioxide adsorption material on carbon dioxide.

[0069] Example 4

[0070] This example is used to judge the concentration of carbon dioxide in the environment.

[0071] In the carbon dioxide industrial carbon capture and carbon dioxide refrigeration process, an important step is to preliminarily enrich carbon dioxide gas under low-temperature conditions, and the low-temperature rapid-response carbon dioxide detection method disclosed in the present application can be applied to this scene. Using the present application, the concentration of carbon dioxide in the enrichment environment can be preliminarily judged through the rapid and obvious color change.

[0072] Specifically, the detected gas is carbon dioxide gas enriched in the environment, the solution obtained in step S1 is injected into the container where the detected gas exists, or the detected gas, hydrogen peroxide and triethylamine are added to the solution obtained in step S1 and shaken, if the color of the solution changes from green to blue instantaneously (≤2s), the concentration of carbon dioxide in the detected gas is greater than 20%; if the color of the solution slowly changes to blue within 60min, the concentration of carbon dioxide in the detected gas is 10%-20%; if the color of the solution has no change within 60min, the concentration of carbon dioxide in the detected gas is less than 10%.

[0073] The application also provides a kit for detecting the concentration of CO2 gas, which comprises a cobalt nitrate complex, a solvent, hydrogen peroxide and triethylamine, wherein the molar concentration of the cobalt nitrate complex solution formed by the cobalt nitrate complex and the solvent is ≥0.001mol / L; the molar ratio of the hydrogen peroxide to the cobalt nitrate complex is ≥1:1; the molar ratio of the triethylamine to the cobalt nitrate complex is ≥0.5:1, and the solvent can be one of acetonitrile, trifluoroethanol, tetrahydrofuran, methanol and N,N-dimethylformamide or a mixed solvent of the above solvents, and a suitable solvent can be selected according to the actual application scene, as long as the solvent can be used in the corresponding application scene.

[0074] Preferably, the storage temperature of the kit is ≤-4℃.

[0075] Those skilled in the art will readily understand that the above description is only a preferred embodiment of the application and is not intended to limit the application, and any modification, equivalent replacement and improvement made within the spirit and principle of the application shall be included in the protection scope of the application.

[0076] Some parts of the description in the specification are not described in detail, the above examples are provided only for the purpose of describing the application, and are not intended to limit the scope of the application. The scope of the application is defined by the appended claims. Any equivalent replacement and modification made without departing from the spirit and principle of the application shall be included in the scope of the application.

Claims

1. A method for detecting CO2 gas concentration, characterized in that, The method for detecting CO2 gas concentration using a cobalt nitrate complex includes the following steps: S1: Dissolve the cobalt nitrate complex in a solvent to prepare a cobalt nitrate complex solution; S2: Add hydrogen peroxide, triethylamine and the gas to be detected to the cobalt nitrate complex solution obtained in step S1. The order of addition of the three is not important. Shake the container. If the solution color changes from green to blue, the detected gas contains CO2 at a concentration greater than 10%; if the solution color remains unchanged for 60 minutes, the concentration of CO2 in the detected gas is less than 10%. The molecular structural formula of the cobalt nitrate complex in step S1 is: ； The solvent in step S1 is one of acetonitrile, methanol, trifluoroethanol, tetrahydrofuran, N,N-dimethylformamide, or a mixture of the above solvents.

2. The method for detecting CO2 gas concentration according to claim 1, characterized in that, In step S2, if the solution color changes from green to blue within 2 seconds, the detected gas contains CO2 with a concentration greater than 20%; if the solution color slowly turns blue within 60 minutes, the concentration of CO2 in the detected gas is 10%~20%; if the solution color remains unchanged for 60 minutes, the concentration of CO2 in the detected gas is less than 10%.

3. The method for detecting CO2 gas concentration according to claim 1, characterized in that, The color response speed of the method for detecting CO2 gas concentration is related to the CO2 gas concentration in the environment being detected.

4. The method for detecting CO2 gas concentration according to claim 1, characterized in that, The structural formula of the color-producing ion in the green solution in step S2 is: ； The structural formula of the color-producing ion in the blue solution in step S2 is: 。 5. The method for detecting CO2 gas concentration according to claim 1, characterized in that, The molar concentration of the cobalt nitrate complex solution in step S1 is ≥0.001 mol / L.

6. The method for detecting CO2 gas concentration according to claim 1, characterized in that, The method for detecting CO2 gas concentration is used at temperatures ranging from -78℃ to 35℃.

7. The method for detecting CO2 gas concentration according to claim 1, characterized in that, The molar ratio of hydrogen peroxide to the cobalt nitrate complex is ≥1:1; the molar ratio of triethylamine to the cobalt nitrate complex is ≥0.5:

1.

8. A reagent kit for detecting CO2 gas concentration, characterized in that, The kit includes a cobalt nitrate complex, a solvent, hydrogen peroxide, and triethylamine, wherein the molar concentration of the cobalt nitrate complex solution formed by the cobalt nitrate complex and the solvent is ≥0.001 mol / L.

9. The kit for detecting CO2 gas concentration according to claim 8, characterized in that, The reagent kit is stored at a temperature of ≤-4℃.

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