Preparation method of fluorescent metal organic framework test paper for detecting sulfur hexafluoride and application in detecting trace sulfur hexafluoride

Abstract

A method for preparing a fluorescent metal organic framework test paper for detecting sulfur hexafluoride and its application in detecting trace sulfur hexafluoride, which relates to a method for preparing a test paper and its application. The purpose of the present invention is to solve the problem that the existing method for detecting SF6 uses large detection equipment, has a long detection time, high detection cost and cumbersome operation. In response to the problems of high detection cost and cumbersome operation of existing SF6 technology, the present invention creatively proposes a Co 2+ As the central ion, combined with lanthanide metal ion Eu 3+ By constructing a three-dimensional cage with a diameter of , a rigid Eu / Co-OCH3@LMOF was self-assembled and attached to filter paper to create a new LMOF detection test paper. This invention introduces LMOFs into the field of gas detection and utilizes the interaction between template molecules, metal ions, and organic ligands to prepare a visual SF6 / N2 detection test paper.

Description

Technical Field

[0001] The invention relates to a preparation method and application of a test paper. Background Art

[0002] Power grid companies utilize a wide range of SF6-insulated equipment, including circuit breakers, high-voltage transformers, gas-enclosed capacitors, high-voltage transmission lines, and instrument transformers. The earliest equipment utilizing SF6 as an insulating gas has been in operation for over twenty years. During installation, operation, and operation, SF6 leakage risks can easily occur due to improper handling. Currently, the main SF6 detection methods include chromatography, laser imaging, helium mass spectrometry, and infrared imaging. However, these methods often utilize large-scale testing equipment, resulting in lengthy testing times, high costs, and cumbersome procedures. Summary of the Invention

[0003] The purpose of the present invention is to solve the problems that the existing method for detecting SF6 uses large detection equipment, has a long detection time, high detection cost and cumbersome operation, and to provide a method for preparing a fluorescent metal organic framework test paper for detecting sulfur hexafluoride and its application in detecting trace sulfur hexafluoride.

[0004] Aiming at the high cost and complicated operation of existing SF6 technology, the present invention creatively proposes a Co 2+ As the central ion, combined with lanthanide metal ion Eu 3+ , the construction space diameter is The researchers used a three-dimensional cage to self-assemble a rigid Eu / Co-OCH3@LMOF, then attached the fluorescent metal-organic framework (LMOF) to filter paper to construct a new LMOF detection test strip. This invention introduces LMOFs into the field of gas detection, utilizing the interaction between template molecules, metal ions, and organic ligands to synthesize LMOFs with specific recognition capabilities, and prepare a visual SF6 / N2 detection test strip.

[0005] The present invention provides a method for preparing a fluorescent metal-organic framework test paper for detecting sulfur hexafluoride, which is specifically completed by the following steps:

[0006] 1. Add Eu(NO3)3·6H2O and [Co(NH3)6]Cl3 to N,N-dimethylformamide, stir magnetically for a period of time, then add 2-methoxyterephthalic acid and 6-carboxypyridine-2-methanol, sonicate for a period of time, then heat to 60°C to 100°C for a period of condensation reflux reaction to obtain a reaction product; wash the reaction product, and then dry it to obtain a fluorescent metal-organic framework;

[0007] 2. Preparation of test strips:

[0008] A fluorescent metal-organic framework is added to N,N-dimethylformamide to obtain a fluorescent metal-organic framework solution; a white filter paper is placed in the fluorescent metal-organic framework solution and allowed to stand for a period of time. After the white filter paper is evenly soaked, it is taken out and dried at room temperature to obtain a fluorescent metal-organic framework test paper for detecting sulfur hexafluoride.

[0009] The fluorescent metal organic framework test paper for detecting sulfur hexafluoride is used to detect trace amounts of sulfur hexafluoride.

[0010] Principle of the present invention:

[0011] The present invention first prepares fluorescent metal organic frameworks (LMOFs). The fluorescent metal organic frameworks (LMOFs) have the characteristics of generating fluorescence by adsorbing guest molecules of fluorophores, and have the advantages of visual and intuitive gas detection. The present invention uses lanthanide metal ions europium ions (Eu 3+ ) and transition metal cobalt ions (Co 2+ ) constructs a dual-center metal-organic framework, in which the lanthanide metal has a very sharp characteristic emission peak, a large fluorescence intensity, a long fluorescence lifetime and a wide fluorescence emission range, and has the advantages of fast response speed, high luminescence intensity and long luminescence time; the present invention uses a fluorescent metal-organic framework to prepare a fluorescent metal-organic framework test paper that selectively adsorbs sulfur hexafluoride, which is used to detect industrial leaks of SF6 gas.

[0012] The beneficial effects of the method for preparing a fluorescent metal organic framework test paper for detecting sulfur hexafluoride of the present invention are embodied in:

[0013] (1) When using the test paper detection method to detect SF6 substances, it has the advantages of simple sample pretreatment, low cost, simple operation, and realizes visual detection;

[0014] (2) Eu element has great advantages and application prospects in fluorescence sensing. Organic ligands sensitize rare earth ions Eu in the form of "antenna effect" 3+ , greatly extending the fluorescence lifetime;

[0015] (3) Since water molecules can easily react with Eu 3+ Coordination, the high-frequency vibration of OH in water molecules will increase the loss of non-radiative energy, resulting in quenching of the fluorescence signal. In the present invention, the ligand is a hydrophobic methoxy group, which ensures the working efficiency of the fluorescent component;

[0016] (4) The spatial cage constructed by the MOF is adapted to the kinetic spatial diameter of SF6, achieving the best trapping effect and improving its selectivity for the gas;

[0017] (5) When SF6 molecules are adsorbed in the pores of MOFs, the electronic properties and dipole moments of MOFs will change. The carboxyl groups will collapse and deform, and the charge transfer mechanism will cause the electron density to drop sharply, resulting in fluorescence quenching. The response time is very short, so the detection time occurs within 3 seconds. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Comparison chart of the fluorescent metal organic framework test paper for detecting sulfur hexafluoride prepared in Example 1 before and after adsorption of different gases and adsorption of SF6;

[0019] Figure 2 This is a comparison diagram of the fluorescent metal organic framework prepared in Example 1 before and after fluorescence quenching;

[0020] Figure 3 The fluorescence intensity graphs of the fluorescent metal organic framework test papers for detecting sulfur hexafluoride prepared at different temperatures in Examples 1 to 5 are shown;

[0021] Figure 4 The fluorescence intensity of the fluorescent metal organic framework test paper for detecting sulfur hexafluoride prepared with different LMOF mass fractions in Examples 1 and Examples 6 to 9;

[0022] Figure 5 The response time of the fluorescent metal organic framework test paper for detecting sulfur hexafluoride prepared in Example 1 to different concentrations of SF6. DETAILED DESCRIPTION

[0023] Specific embodiment 1: This embodiment is a method for preparing a fluorescent metal organic framework test paper for detecting sulfur hexafluoride, which is specifically completed by the following steps:

[0024] 1. Add Eu(NO3)3·6H2O and [Co(NH3)6]Cl3 to N,N-dimethylformamide, stir magnetically for a period of time, then add 2-methoxyterephthalic acid and 6-carboxypyridine-2-methanol, sonicate for a period of time, then heat to 60°C to 100°C for a period of condensation reflux reaction to obtain a reaction product; wash the reaction product, and then dry it to obtain a fluorescent metal-organic framework;

[0025] 2. Preparation of test strips:

[0026] A fluorescent metal-organic framework is added to N,N-dimethylformamide to obtain a fluorescent metal-organic framework solution; a white filter paper is placed in the fluorescent metal-organic framework solution and allowed to stand for a period of time. After the white filter paper is evenly soaked, it is taken out and dried at room temperature to obtain a fluorescent metal-organic framework test paper for detecting sulfur hexafluoride.

[0027] Specific embodiment 2: This embodiment differs from specific embodiment 1 in that the mass volume ratio of Eu(NO3)3·6H2O, [Co(NH3)6]Cl3, and N,N-dimethylformamide described in step 1 is (5g-7g):(2g-3g):100mL. The other steps are the same as specific embodiment 1.

[0028] Specific Embodiment 3: This embodiment differs from Specific Embodiments 1 or 2 in that the mass-to-volume ratio of 2-methoxyterephthalic acid, 6-carboxypyridine-2-methanol, and N,N-dimethylformamide in Step 1 is (2 g to 5 g): (10 mL to 12 mL): 100 mL. Other steps are the same as Specific Embodiments 1 or 2.

[0029] Specific embodiment 4: This embodiment differs from specific embodiments 1 to 3 in that the magnetic stirring time in step 1 is 3 to 5 hours. The other steps are the same as those in specific embodiments 1 to 3.

[0030] Specific embodiment 5: This embodiment differs from specific embodiments 1 to 4 in that the ultrasonication time in step 1 is 20 to 40 minutes. The other steps are the same as those in specific embodiments 1 to 4.

[0031] Specific embodiment 6: This embodiment differs from specific embodiments 1 to 5 in that the condensation reflux reaction time in step 1 is 10 hours to 14 hours. The other steps are the same as those in specific embodiments 1 to 5.

[0032] Specific Embodiment 7: This embodiment differs from Specific Embodiments 1 to 6 in that: in step 1, the reaction product is rinsed with N,N-dimethylformamide every 5 to 7 hours, for a total of 4 to 5 rinses; the drying temperature in step 1 is 50°C to 60°C, and the drying time is 10 to 12 hours. The other steps are the same as Specific Embodiments 1 to 6.

[0033] Specific embodiment 8: This embodiment differs from specific embodiments 1 to 7 in that the mass fraction of the fluorescent metal organic framework solution in step 2 is 5% to 25%. The other steps are the same as specific embodiments 1 to 7.

[0034] Specific embodiment 9: This embodiment differs from specific embodiments 1 to 8 in that the resting time in step 2 is 0.5 to 2 minutes, and the drying time at room temperature in step 2 is 10 to 15 minutes. The other steps are the same as those in specific embodiments 1 to 8.

[0035] Specific embodiment ten: This embodiment is that the fluorescent metal organic framework test paper for detecting sulfur hexafluoride is used to detect trace amounts of sulfur hexafluoride.

[0036] The following examples are used to verify the beneficial effects of the present invention:

[0037] Example 1: A method for preparing a fluorescent metal-organic framework test paper for detecting sulfur hexafluoride is specifically completed by the following steps:

[0038] 1. Add 6.48g Eu(NO3)3·6H2O and 2.52g [Co(NH3)6]Cl3 to 100mL N,N-dimethylformamide, stir magnetically for 4h, then add 3.92g 2-methoxyterephthalic acid and 11mL 6-carboxypyridine-2-methanol, ultrasonicate for 30min, then heat to 60℃ and reflux for 12h to obtain a reaction product; wash the reaction product and then dry it at 50℃ for 12h to obtain a fluorescent metal organic framework (LMOF);

[0039] In step 1, the reaction product was rinsed with N,N-dimethylformamide once every 6 hours for a total of 4 times;

[0040] 2. Preparation of test strips:

[0041] A fluorescent metal-organic framework is added to N,N-dimethylformamide to obtain a fluorescent metal-organic framework solution; a white filter paper is placed in the fluorescent metal-organic framework solution and allowed to stand for 1 minute. After the white filter paper is evenly soaked, it is taken out and dried at room temperature for 10 minutes to obtain a fluorescent metal-organic framework test paper for detecting sulfur hexafluoride;

[0042] The mass fraction of the fluorescent metal organic framework solution in step 2 is 20%.

[0043] Example 2: A method for preparing a fluorescent metal-organic framework test paper for detecting sulfur hexafluoride is specifically completed by the following steps:

[0044] 1. Add 6.48g Eu(NO3)3·6H2O and 2.52g [Co(NH3)6]Cl3 to 100mL N,N-dimethylformamide, stir magnetically for 4h, then add 3.92g 2-methoxyterephthalic acid and 11mL 6-carboxypyridine-2-methanol, ultrasonicate for 30min, then heat to 70℃ and reflux under condensation for 12h to obtain a reaction product; wash the reaction product and then dry it at 50℃ for 12h to obtain a fluorescent metal organic framework (LMOF);

[0045] In step 1, the reaction product was rinsed with N,N-dimethylformamide once every 6 hours for a total of 4 times;

[0046] 2. Preparation of test strips:

[0047] A fluorescent metal-organic framework is added to N,N-dimethylformamide to obtain a fluorescent metal-organic framework solution; a white filter paper is placed in the fluorescent metal-organic framework solution and allowed to stand for 1 minute. After the white filter paper is evenly soaked, it is taken out and dried at room temperature for 10 minutes to obtain a fluorescent metal-organic framework test paper for detecting sulfur hexafluoride;

[0048] The mass fraction of the fluorescent metal organic framework solution in step 2 is 20%.

[0049] Example 3: A method for preparing a fluorescent metal-organic framework test paper for detecting sulfur hexafluoride is specifically completed by the following steps:

[0050] 1. Add 6.48g Eu(NO3)3·6H2O and 2.52g [Co(NH3)6]Cl3 to 100mL N,N-dimethylformamide, stir magnetically for 4h, then add 3.92g 2-methoxyterephthalic acid and 11mL 6-carboxypyridine-2-methanol, ultrasonicate for 30min, then heat to 80℃ and reflux for 12h to obtain a reaction product; wash the reaction product and then dry it at 50℃ for 12h to obtain a fluorescent metal organic framework (LMOF);

[0051] In step 1, the reaction product was rinsed with N,N-dimethylformamide once every 6 hours, for a total of 4 times;

[0052] 2. Preparation of test strips:

[0053] A fluorescent metal-organic framework is added to N,N-dimethylformamide to obtain a fluorescent metal-organic framework solution; a white filter paper is placed in the fluorescent metal-organic framework solution and allowed to stand for 1 minute. After the white filter paper is evenly soaked, it is taken out and dried at room temperature for 10 minutes to obtain a fluorescent metal-organic framework test paper for detecting sulfur hexafluoride;

[0054] The mass fraction of the fluorescent metal organic framework solution in step 2 is 20%.

[0055] Example 4: A method for preparing a fluorescent metal-organic framework test paper for detecting sulfur hexafluoride is specifically completed by the following steps:

[0056] 1. Add 6.48g Eu(NO3)3·6H2O and 2.52g [Co(NH3)6]Cl3 to 100mL N,N-dimethylformamide, stir magnetically for 4h, then add 3.92g 2-methoxyterephthalic acid and 11mL 6-carboxypyridine-2-methanol, ultrasonicate for 30min, then heat to 90℃ and reflux for 12h to obtain a reaction product; wash the reaction product and then dry it at 50℃ for 12h to obtain a fluorescent metal organic framework (LMOF);

[0057] In step 1, the reaction product was rinsed with N,N-dimethylformamide once every 6 hours for a total of 4 times;

[0058] 2. Preparation of test strips:

[0059] A fluorescent metal-organic framework is added to N,N-dimethylformamide to obtain a fluorescent metal-organic framework solution; a white filter paper is placed in the fluorescent metal-organic framework solution and allowed to stand for 1 minute. After the white filter paper is evenly soaked, it is taken out and dried at room temperature for 10 minutes to obtain a fluorescent metal-organic framework test paper for detecting sulfur hexafluoride;

[0060] The mass fraction of the fluorescent metal organic framework solution in step 2 is 20%.

[0061] Example 5: A method for preparing a fluorescent metal-organic framework test paper for detecting sulfur hexafluoride is specifically completed by the following steps:

[0062] 1. Add 6.48g Eu(NO3)3·6H2O and 2.52g [Co(NH3)6]Cl3 to 100mL N,N-dimethylformamide and stir magnetically for 4h. Then add 3.92g 2-methoxyterephthalic acid and 11mL 6-carboxypyridine-2-methanol and ultrasonicate for 30min. Then heat to 100℃ and reflux under condensation for 12h to obtain a reaction product. Wash the reaction product and dry it at 50℃ for 12h to obtain a fluorescent metal organic framework (LMOF).

[0063] In step 1, the reaction product was rinsed with N,N-dimethylformamide once every 6 hours for a total of 4 times;

[0064] 2. Preparation of test strips:

[0065] A fluorescent metal-organic framework is added to N,N-dimethylformamide to obtain a fluorescent metal-organic framework solution; a white filter paper is placed in the fluorescent metal-organic framework solution and allowed to stand for 1 minute. After the white filter paper is evenly soaked, it is taken out and dried at room temperature for 10 minutes to obtain a fluorescent metal-organic framework test paper for detecting sulfur hexafluoride;

[0066] The mass fraction of the fluorescent metal organic framework solution in step 2 is 20%.

[0067] Example 6: This example differs from Example 1 in that the mass fraction of the fluorescent metal organic framework solution in step 2 is 5%. Other steps and parameters are the same as those in Example 1.

[0068] Example 7: This example differs from Example 1 in that the mass fraction of the fluorescent metal organic framework solution in step 2 is 10%. Other steps and parameters are the same as those in Example 1.

[0069] Example 8: This example differs from Example 1 in that the mass fraction of the fluorescent metal organic framework solution in step 2 is 15%. Other steps and parameters are the same as those in Example 1.

[0070] Example 9: This example differs from Example 1 in that the mass fraction of the fluorescent metal organic framework solution in step 2 is 25%. Other steps and parameters are the same as those in Example 1.

[0071] Figure 1 Comparison chart of the fluorescent metal organic framework test paper for detecting sulfur hexafluoride prepared in Example 1 before and after adsorption of different gases and adsorption of SF6;

[0072] Figure 2 This is a comparison diagram of the fluorescent metal organic framework prepared in Example 1 before and after fluorescence quenching;

[0073] from Figures 1 and 2 It can be seen that when SF6 gas molecules enter the LMOF molecular cage, fluorescence quenching occurs and the LMOF exhibits high specificity for SF6 molecules. The constructed LMOF exhibits excellent performance in SF6 detection.

[0074] Figure 3 The fluorescence intensity graphs of the fluorescent metal organic framework test papers for detecting sulfur hexafluoride prepared at different temperatures in Examples 1 to 5;

[0075] Figure 4 The fluorescence intensity of the fluorescent metal organic framework test paper for detecting sulfur hexafluoride prepared with different LMOF mass fractions in Examples 1 and Examples 6 to 9.

[0076] from Figures 3 and 4 As the synthesis temperature gradually increases, the LMOF synthesis improves, and the fluorescence intensity increases, reaching saturation near 80°C and beginning to decline after 100°C. Similarly, the fluorescence intensity increases with increasing LMOF mass fraction, approaching saturation at 20%. This demonstrates that the optimal preparation temperature for the material is 80°C, and the test paper uses a 20% LMOF solution.

[0077] Figure 5 The response time of the fluorescent metal organic framework test paper for detecting sulfur hexafluoride prepared in Example 1 to different concentrations of SF6.

[0078] from Figure 5 It can be seen that when the SF6 concentration is higher than 1ppm, the test paper has a response time to the leaked gas, which is 20s at 1ppm and less than or equal to 2s when it is above 10ppm.

Claims

1. A method for preparing a fluorescent metal organic framework test paper for detecting sulfur hexafluoride, characterized in that The preparation method is specifically completed according to the following steps:

1. Add Eu(NO3)3·6H2O and [Co(NH3)6]Cl3 to N,N-dimethylformamide, stir magnetically for a period of time, then add 2-methoxyterephthalic acid and 6-carboxypyridine-2-methanol, sonicate for a period of time, then heat to 60°C to 100°C for a period of condensation reflux reaction to obtain a reaction product; wash the reaction product, and then dry it to obtain a fluorescent metal-organic framework; 2. Preparation of test strips: A fluorescent metal-organic framework is added to N,N-dimethylformamide to obtain a fluorescent metal-organic framework solution; a white filter paper is placed in the fluorescent metal-organic framework solution and allowed to stand for a period of time. After the white filter paper is evenly soaked, it is taken out and dried at room temperature to obtain a fluorescent metal-organic framework test paper for detecting sulfur hexafluoride.

2. The method for preparing a fluorescent metal organic framework test paper for detecting sulfur hexafluoride according to claim 1, characterized in that The mass volume ratio of Eu(NO3)3·6H2O, [Co(NH3)6]Cl3 and N,N-dimethylformamide described in step 1 is (5g~7g):(2g~3g):100mL.

3. The method for preparing a fluorescent metal organic framework test paper for detecting sulfur hexafluoride according to claim 1, characterized in that The mass volume ratio of 2-methoxyterephthalic acid, 6-carboxypyridine-2-methanol and N,N-dimethylformamide described in step 1 is (2g~5g):(10mL~12mL):100mL.

4. The method for preparing a fluorescent metal organic framework test paper for detecting sulfur hexafluoride according to claim 1, characterized in that The magnetic stirring time in step 1 is 3 h to 5 h.

5. The method for preparing a fluorescent metal organic framework test paper for detecting sulfur hexafluoride according to claim 1, characterized in that The ultrasonication time in step 1 is 20 to 40 minutes.

6. The method for preparing a fluorescent metal organic framework test paper for detecting sulfur hexafluoride according to claim 1, characterized in that The condensation reflux reaction time in step 1 is 10 h to 14 h.

7. The method for preparing a fluorescent metal organic framework test paper for detecting sulfur hexafluoride according to claim 1, characterized in that In step 1, the reaction product is rinsed with N,N-dimethylformamide every 5 to 7 hours, for a total of 4 to 5 times; the drying temperature in step 1 is 50° C. to 60° C., and the drying time is 10 to 12 hours.

8. The method for preparing a fluorescent metal organic framework test paper for detecting sulfur hexafluoride according to claim 1, characterized in that The mass fraction of the fluorescent metal organic framework solution in step 2 is 5% to 25%.

9. The method for preparing a fluorescent metal organic framework test paper for detecting sulfur hexafluoride according to claim 1, characterized in that The standing time in step 2 is 0.5 min to 2 min; the room temperature drying time in step 2 is 10 min to 15 min.

10. Use of a fluorescent metal organic framework test paper for detecting sulfur hexafluoride prepared by the preparation method according to claim 1, characterized in that The fluorescent metal organic framework test paper for detecting sulfur hexafluoride is used to detect trace amounts of sulfur hexafluoride.

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