Based on Ti 3 C 2 Surface-enhanced Raman Detection Method for Furfural in Transformer Oil Based on Tx / AgNWs Composite Substrate

Abstract

The present invention provides a method for surface-enhanced Raman detection of furfural in transformer oil based on a Ti3C2Tx / AgNWs composite substrate, comprising the following steps: preparation of an AgNWs solution, synthesis of a Ti3C2Tx two-dimensional nanosheet solution, preparation of a Ti3C2Tx / AgNWs composite substrate, and detection of furfural in transformer oil based on a Raman spectroscopy detection platform. By selecting the Raman characteristic peak intensity at 1705 cm ‑1 of the furfural molecule and using a least squares quantitative detection model, the furfural concentration in the transformer oil is obtained. This method can effectively detect the content of dissolved furfural in transformer oil, and has the characteristics of high sensitivity, rapidity and convenient operation.

Description

Technical Field

[0001] The invention relates to the technical field of online monitoring of electrical equipment, and in particular to a surface enhanced Raman detection method for furfural in transformer oil based on a Ti3C2Tx / AgNWs composite substrate. Background Art

[0002] As the transformer operates for a long time, the oil-paper insulation material inside it will gradually age due to the continuous influence of factors such as thermal stress, electric field stress and mechanical stress, which will lead to a decrease in the insulation performance of the transformer, thereby threatening the safe and stable operation of the transformer and the power system.

[0003] Furfural is produced by the decomposition of cellulose molecules in transformer insulation paper. It is an important characteristic substance generated during the aging process of oil-paper insulation materials. The concentration of furfural in transformer oil is considered to be a key indicator that can reflect its aging degree. Therefore, accurate detection of furfural content in transformer oil is of great significance for evaluating the aging degree of power transformers and ensuring the healthy and stable operation of transformers.

[0004] At present, traditional furfural detection technologies such as high performance liquid chromatography, spectrophotometry, colorimetry, etc. have defects such as cumbersome operation, long detection cycle or susceptibility to interference. The inventors of this application have found through research and analysis that surface enhanced Raman scattering (SERS) technology, as a characterization technology that can analyze substances adsorbed on the surface of precious metal nanostructures at the single molecule level, has high sensitivity and the ability to obtain molecular fingerprint information without labeling. In addition, this technology has a short detection cycle, is not easily interfered with, is easy to operate, and does not require cumbersome pretreatment processes. Therefore, it is very necessary to innovatively apply SERS technology to the detection of dissolved furfural content in oil. Summary of the invention

[0005] In view of the technical problems that the existing furfural detection technology in transformer oil has complicated operation, long detection cycle or susceptibility to interference, the present invention provides a surface enhanced Raman detection method for furfural in transformer oil based on Ti3C2Tx / AgNWs composite substrate.

[0006] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0007] The surface enhanced Raman detection method of furfural in transformer oil based on Ti3C2Tx / AgNWs composite substrate comprises the following steps:

[0008] Preparation of AgNWs solution: NaCl solution is added to the ethylene glycol solution of PVP, and the mixed solution is placed in a flask and stirred continuously; at the same time, the ethylene glycol solution of AgNO3 is injected into the flask, and the AgNWs solution, i.e., the linear silver nanostructure solution, is obtained after continuous stirring;

[0009] Synthesis of Ti3C2Tx two-dimensional nanosheet solution: In a polytetrafluoroethylene environment, pour LiF powder into hydrochloric acid and stir until fully dissolved, then add Ti3AlC2 powder to the mixed solution several times, stir until completely mixed in a sealed environment, transfer the mixed solution to an oil bath and react at a constant temperature for a predetermined time to obtain a Ti3C2Tx two-dimensional nanosheet solution;

[0010] Preparation of Ti3C2Tx / AgNWs composite substrate: AgNWs solution and Ti3C2Tx two-dimensional nanosheet solution were fully stirred, dropped onto a clean silicon wafer, and heated and dried to obtain a Ti3C2Tx / AgNWs composite substrate;

[0011] SERS detection: prepare furfural solutions dissolved in transformer oil of different concentrations as test samples, put the prepared Ti3C2Tx / AgNWs composite substrate and the test samples into a cuvette, collect Raman spectrum data of the test samples in the cuvette based on the Raman spectrum detection platform, use the least squares quantitative detection model, and substitute the furfural molecule 1705cm -1 The intensity of the Raman characteristic peak is measured to obtain the furfural concentration in the sample to be tested.

[0012] As an embodiment, the specific preparation process of the AgNWs solution is: add 8 mg of 99.5% NaCl solution to 10 ml of 0.4 mol / L PVP ethylene glycol solution, pour the mixed solution into a two-necked flask, and continue stirring at 170°C; at the same time, slowly inject 6 ml of 0.15 mol / L AgNO3 ethylene glycol solution into the two-necked flask, control the injection rate to 0.15 ml / min, and keep stirring at 170°C for 80 minutes to obtain the AgNWs solution.

[0013] As an embodiment, the specific preparation process of the Ti3C2Tx two-dimensional nanosheet solution is: add 9M hydrochloric acid to 10ml of polytetrafluoroethylene, pour 0.8g of LiF powder into the hydrochloric acid, and stir for 5min to fully dissolve the LiF powder; then add 0.5g of Ti3AlC2 powder to the mixed solution twice and stir until completely mixed in a sealed environment, 0.25g each time and at an interval of 6min, transfer the mixed solution to a 40°C oil bath and stir for reaction for 24h, and use anhydrous ethanol to centrifuge and wash the reaction liquid 8 times to make the pH value of the system>6.

[0014] As an embodiment, the specific preparation process of the Ti3C2Tx / AgNWs composite substrate is: after mixing 0.1 mg / ml AgNWs solution and 0.03 mg / ml Ti3C2Tx two-dimensional nanosheet solution for 6 hours, drip it on the surface of a clean polycrystalline silicon wafer, and place it on a hot plate at 70°C for heating and drying.

[0015] As an implementation mode, the specific preparation process of preparing furfural solutions dissolved in transformer oil of different concentrations is as follows: 1.5 ml of furfural is measured and dissolved in 1 L of transformer oil, and diluted according to a 2-fold concentration gradient to obtain furfural-transformer oil solutions with concentrations of 1740 mg / L, 870 mg / L, 435 mg / L, 217.5 mg / L, 108.8 mg / L, 54.4 mg / L, 27.2 mg / L, and 13.6 mg / L, respectively.

[0016] As an implementation mode, when the Raman spectrum data of the sample to be tested in the cuvette is collected based on the Raman spectrum detection platform, a spectrometer is used to test the Raman spectrum intensity of the sample to be tested. The specific detection conditions are as follows: the laser excitation wavelength is 532nm, the laser power is 30mV, the integration time is 1s, the number of integrations is 10, and 3 groups of Raman spectrum data at different points are collected for each sample, and the average value is taken as the final detection result.

[0017] Compared with the prior art, the surface enhanced Raman detection method for furfural in transformer oil based on Ti3C2Tx / AgNWs composite substrate provided by the present invention has the following advantages:

[0018] 1. The present invention combines metal nanomaterials AgNWs with two-dimensional materials Ti3C2Tx to prepare Ti3C2Tx / AgNWs composite substrates. Since AgNWs have excellent localized surface plasmon resonance effect and Ti3C2Tx has a large specific surface area and excellent conductivity, Ti3C2Tx can adsorb a large number of Ag nanostructures and molecules of the substance to be tested, and promote EM effect and CM effect, so that the intensity of the Raman scattering signal is greatly improved, which has a surface enhancement effect on the Raman signal.

[0019] 2. The Ti3C2Tx / AgNWs composite substrate in the present invention can effectively detect the furfural content in transformer oil, and therefore is of great significance for monitoring the health of the transformer oil-paper insulation system and maintaining the safety and stability of the power system.

[0020] 3. The present invention uses the least square method to calculate the furfural molecule 1705cm -1 The Raman characteristic peak intensity at and its corresponding concentration are linearly fitted to achieve rapid detection of furfural content in transformer oil.

[0021] 4. The present invention overcomes the problems of the traditional furfural detection method, such as cumbersome operation, susceptibility to interference, and long detection cycle, and significantly improves the detection speed and reliability of furfural in transformer oil, and has the characteristics of high sensitivity and rapidity and convenience. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The present invention provides a schematic flow chart of a method for surface enhanced Raman detection of furfural in transformer oil based on a Ti3C2Tx / AgNWs composite substrate.

[0023] Figure 2 It is a schematic diagram of SERS detection using Ti3C2Tx and AgNWs as substrates provided by the present invention.

[0024] Figure 3 It is a comparison diagram of R6G Raman spectra obtained on different Ti3C2Tx / AgNWs composite substrates provided by the present invention.

[0025] Figure 4 The present invention provides a Raman spectrum comparison diagram of furfural, transformer oil and furfural-transformer oil.

[0026] Figure 5 It is the SERS spectra of furfural-transformer oil with different concentrations provided by the present invention.

[0027] Figure 6 It is a schematic diagram of the fitting results of furfural concentration and Raman characteristic peak intensity provided by the present invention. DETAILED DESCRIPTION

[0028] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further described below with reference to specific diagrams.

[0029] Please refer to Figure 1 and Figure 2 As shown, the present invention provides a surface enhanced Raman detection method for furfural in transformer oil based on Ti3C2Tx / AgNWs composite substrate, comprising the following steps:

[0030] Preparation of AgNWs solution: NaCl solution is added to the ethylene glycol solution of PVP, and the mixed solution is placed in a flask and stirred continuously; at the same time, the ethylene glycol solution of AgNO3 is injected into the flask, and the AgNWs solution, i.e., the linear silver nanostructure solution, is obtained after continuous stirring;

[0031] Synthesis of Ti3C2Tx two-dimensional nanosheet solution: In a polytetrafluoroethylene environment, pour LiF powder into hydrochloric acid and stir until fully dissolved, then add Ti3AlC2 powder to the mixed solution several times, stir until completely mixed in a sealed environment, transfer the mixed solution to an oil bath and react at a constant temperature for a predetermined time to obtain a Ti3C2Tx two-dimensional nanosheet solution;

[0032] Preparation of Ti3C2Tx / AgNWs composite substrate: AgNWs solution and Ti3C2Tx two-dimensional nanosheet solution were fully stirred, dropped onto a clean silicon wafer, and heated and dried to obtain a Ti3C2Tx / AgNWs composite substrate;

[0033] SERS detection: prepare furfural solutions dissolved in transformer oil of different concentrations as test samples, put the prepared Ti3C2Tx / AgNWs composite substrate and the test samples into a cuvette such as a quartz cuvette, collect Raman spectrum data of the test samples in the cuvette based on the Raman spectrum detection platform, use the least squares quantitative detection model, and substitute the furfural molecule 1705cm -1 The intensity of the Raman characteristic peak is measured to obtain the furfural concentration in the sample to be tested.

[0034] As an embodiment, the specific preparation process of the AgNWs solution is as follows: add 8 mg of 99.5% NaCl solution to 10 ml of 0.4 mol / L PVP ethylene glycol solution, pour the mixed solution into a two-necked flask, and stir continuously at 170°C; at the same time, slowly inject 6 ml of 0.15 mol / L AgNO3 ethylene glycol solution into the two-necked flask, control the injection rate to 0.15 ml / min, and keep stirring continuously at 170°C for 80 min to obtain the AgNWs solution. This embodiment is easy to operate, and the generated Ag nanostructure has a high aspect ratio. As a SERS substrate, it is easy to produce a localized surface plasmon resonance effect, which triggers the enhancement of the local electromagnetic field and helps to enhance the Raman signal.

[0035] As an embodiment, the specific preparation process of the Ti3C2Tx two-dimensional nanosheet solution is as follows: 9M hydrochloric acid is added to 10ml of polytetrafluoroethylene, 0.8g of LiF powder is poured into the hydrochloric acid, and stirred for 5min to fully dissolve the LiF powder; then 0.5g of Ti3AlC2 powder is added to the mixed solution twice in a sealed environment and stirred until completely mixed, 0.25g each time and 6min apart, the mixed solution is transferred to a 40°C oil bath pot and stirred for 24h, and the liquid obtained by the reaction is centrifuged and washed 8 times with anhydrous ethanol to make the pH value of the system>6. This embodiment is easy to operate, and the generated Ti3C2Tx two-dimensional nanosheets are relatively uniform, with rich functional groups on the surface. As a SERS substrate, it is conducive to adsorbing a large number of molecules to be tested and undergoing charge transfer and chemical bonding processes with them, thereby helping to enhance the Raman signal.

[0036] As an implementation mode, the specific preparation process of the Ti3C2Tx / AgNWs composite substrate is as follows: the AgNWs solution and the Ti3C2Tx two-dimensional nanosheet solution are ultrasonically treated for 30 minutes respectively, and the 0.1 mg / ml AgNWs solution and the 0.03 mg / ml Ti3C2Tx two-dimensional nanosheet solution are mixed and stirred for 6 hours, and then dripped onto the surface of a clean polycrystalline silicon wafer, and placed on a 70°C hot plate for heating and drying. The Ti3C2Tx / AgNWs composite substrate prepared by this implementation mode facilitates the full adsorption of the silver nanostructure on the surface of the Ti3C2Tx nanosheet to promote the Raman enhancement effect of the substrate.

[0037] In order to explore the optimal combination ratio of Ti3C2Tx solution and AgNWs solution, an equal amount of anhydrous ethanol was used as solvent, and Ti3C2Tx solutions with concentrations of 0.01 mg / ml, 0.02 mg / ml, 0.03 mg / ml, 0.05 mg / ml, and 0.08 mg / ml were mixed with 0.1 mg / ml AgNWs solution, and then Ti3C2Tx / AgNWs composite substrates were prepared respectively. -5 mol / L R6G solution was used for comparative testing of the substrate. Figure 3 The Raman spectra of R6G obtained on different Ti3C2Tx / AgNWs composite substrates are shown. Figure 3 It can be seen that combining 0.03 mg / ml Ti3C2Tx with 0.1 mg / ml AgNWs as a composite substrate can achieve the best enhancement effect on the Raman signal.

[0038] As an implementation mode, the specific preparation process of preparing furfural solutions dissolved in transformer oil of different concentrations is as follows: 1.5 ml of furfural is measured and dissolved in 1 L of transformer oil, sealed and ultrasonicated for 20 minutes, and magnetically stirred for 60 minutes to completely dissolve the furfural; then, 50 ml of furfural-transformer oil solution is diluted according to a 2-fold concentration gradient, and 50 ml of new transformer oil is added; and so on, furfural-transformer oil solutions with concentrations of 1740 mg / L, 870 mg / L, 435 mg / L, 217.5 mg / L, 108.8 mg / L, 54.4 mg / L, 27.2 mg / L, and 13.6 mg / L are obtained. Figure 4 The Raman spectra of furfural, transformer oil and furfural-transformer oil are compared. The rich background noise of transformer oil covers most of the characteristic signals of furfural, making it difficult to detect furfural in transformer oil. Due to the interference of transformer oil molecules and substrate, the furfural molecule is originally located at 1665cm -1 The characteristic peak at 1705 cm -1 The signal at this location can be used as a marker to characterize the furfural content.

[0039] As an implementation method, a small amount of the sample to be tested is measured with a pipette to fill a cuvette, and the prepared Ti3C2Tx / AgNWs composite substrate is placed in the cuvette, which is sealed with a sealant to prevent the volatilization of furfural, and is allowed to stand in the dark for 24 hours to allow the furfural molecules to fully contact with the composite substrate.

[0040] As an implementation mode, when the Raman spectrum data of the sample to be tested in the cuvette is collected based on the Raman spectrum detection platform, a spectrometer is used to test the Raman spectrum intensity of the sample to be tested. The specific detection conditions are as follows: the laser excitation wavelength is 532nm, the laser power is 30mV, the integration time is 1s, the number of integrations is 10, and 3 groups of Raman spectrum data at different points are collected for each sample, and the average value is taken as the final detection result.

[0041] As a specific implementation, after dilution and constant volume, the concentration gradient of furfural in transformer oil is 435 mg / L, 217.5 mg / L, 108.8 mg / L, 54.4 mg / L, 27.2 mg / L, and 13.6 mg / L. A Raman spectrometer is used to detect the sample to be tested, and the collected Raman spectrum data is preprocessed by removing the baseline and removing the noise. When the furfural concentration is lower than 13.6 mg / L, its 1705 cm -1 The signal of the characteristic peak at is extremely weak, so the detection limit of furfural content in transformer oil using this method is about 13.6 mg / L. Figure 5 shown.

[0042] As a specific implementation method, reliable quantitative and qualitative analysis of Raman spectroscopy data is an important step in the precise development of this technology. The least squares method is used to calculate the furfural molecule 1705 cm -1 The Raman characteristic peak intensity at the position is fitted and analyzed with its corresponding concentration. For the fitting results, please refer to Figure 6 As shown. Figure 6 The fitting results show that when the furfural concentration is in the range of 13.6 mg / L to 435 mg / L, there is a good linear relationship between the Raman signal intensity and the furfural molecular concentration. The established fitting regression equation is Y=245.97+28.49X, and the goodness of fit R 2 It is 0.9814.

[0043] In summary, the present invention uses surface enhanced Raman spectroscopy to detect the furfural content in transformer oil, combines metal nanomaterials AgNWs with two-dimensional materials Ti3C2Tx to prepare Ti3C2Tx / AgNWs composite substrates, which can quickly detect the furfural content in transformer oil, and uses the least squares method to establish the furfural molecule 1705cm -1 The linear relationship between the characteristic peak intensity at and the furfural concentration in the oil was determined, and the minimum detection concentration was determined to be 13.6 mg / L, which provides a new idea for online detection of transformers. Compared with the prior art, the surface enhanced Raman detection method for furfural in transformer oil based on Ti3C2Tx / AgNWs composite substrate provided by the present invention has the following advantages:

[0044] 1. The present invention combines metal nanomaterials AgNWs with two-dimensional materials Ti3C2Tx to prepare Ti3C2Tx / AgNWs composite substrates. Since AgNWs have excellent localized surface plasmon resonance effect and Ti3C2Tx has a large specific surface area and excellent conductivity, Ti3C2Tx can adsorb a large number of Ag nanostructures and molecules of the substance to be tested, and promote EM effect and CM effect, so that the intensity of the Raman scattering signal is greatly improved, which has a surface enhancement effect on the Raman signal.

[0045] 2. The Ti3C2Tx / AgNWs composite substrate in the present invention can effectively detect the furfural content in transformer oil, and therefore is of great significance for monitoring the health of the transformer oil-paper insulation system and maintaining the safety and stability of the power system.

[0046] 3. The present invention uses the least square method to calculate the furfural molecule 1705cm -1 The Raman characteristic peak intensity at and its corresponding concentration are linearly fitted to achieve rapid detection of furfural content in transformer oil.

[0047] 4. The present invention overcomes the problems of the traditional furfural detection method, such as cumbersome operation, susceptibility to interference, and long detection cycle, and significantly improves the detection speed and reliability of furfural in transformer oil, and has the characteristics of high sensitivity and rapidity and convenience.

[0048] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the present invention, which should be included in the scope of the claims of the present invention.

Claims

1. A surface enhanced Raman detection method for furfural in transformer oil based on Ti3C2Tx / AgNWs composite substrate, characterized in that: The following steps are involved: Preparation of AgNWs solution: Add NaCl solution to the ethylene glycol solution of PVP, and place the mixed solution in a flask and stir continuously; At the same time, the ethylene glycol solution of AgNO3 was injected into the flask, and AgNWs solution, i.e., linear silver nanostructure solution, was obtained after continuous stirring; Synthesis of Ti3C2Tx two-dimensional nanosheet solution: In a polytetrafluoroethylene environment, pour LiF powder into hydrochloric acid and stir until fully dissolved, then add Ti3AlC2 powder to the mixed solution several times, stir until completely mixed in a sealed environment, transfer the mixed solution to an oil bath and react at a constant temperature for a predetermined time to obtain a Ti3C2Tx two-dimensional nanosheet solution; Preparation of Ti3C2Tx / AgNWs composite substrate: AgNWs solution and Ti3C2Tx two-dimensional nanosheet solution were fully stirred, dropped onto a clean silicon wafer, and heated and dried to obtain a Ti3C2Tx / AgNWs composite substrate; SERS detection: prepare furfural solutions dissolved in transformer oil of different concentrations as test samples, put the prepared Ti3C2Tx / AgNWs composite substrate and the test samples into a cuvette, collect Raman spectrum data of the test samples in the cuvette based on the Raman spectrum detection platform, use the least squares quantitative detection model, and substitute the furfural molecule 1705cm -1 The intensity of the Raman characteristic peak is measured to obtain the furfural concentration in the sample to be tested.

2. The surface enhanced Raman detection method for furfural in transformer oil based on Ti3C2Tx / AgNWs composite substrate according to claim 1, characterized in that: The specific preparation process of the AgNWs solution is as follows: add 8 mg of 99.5% NaCl solution to 10 ml of 0.4 mol / L PVP ethylene glycol solution, pour the mixed solution into a two-necked flask, and continue stirring at 170°C; at the same time, slowly inject 6 ml of 0.15 mol / L AgNO3 ethylene glycol solution into the two-necked flask, control the injection rate to 0.15 ml / min, and keep stirring at 170°C for 80 min to obtain the AgNWs solution.

3. The surface enhanced Raman detection method for furfural in transformer oil based on Ti3C2Tx / AgNWs composite substrate according to claim 1, characterized in that: The specific preparation process of the Ti3C2Tx two-dimensional nanosheet solution is as follows: 9M hydrochloric acid is added to 10ml of polytetrafluoroethylene, 0.8g of LiF powder is poured into the hydrochloric acid, and stirred for 5min to fully dissolve the LiF powder; then 0.5g of Ti3AlC2 powder is added to the mixed solution twice and stirred until completely mixed in a sealed environment, 0.25g each time and 6min intervals, the mixed solution is transferred to a 40°C oil bath and stirred for reaction for 24h, and the reaction liquid is centrifuged and washed 8 times with anhydrous ethanol to make the pH value of the system>6.

4. The surface enhanced Raman detection method for furfural in transformer oil based on Ti3C2Tx / AgNWs composite substrate according to claim 1, characterized in that: The specific preparation process of the Ti3C2Tx / AgNWs composite substrate is as follows: 0.1 mg / ml AgNWs solution and 0.03 mg / ml Ti3C2Tx two-dimensional nanosheet solution are mixed and stirred for 6 hours, then dripped onto the surface of a clean polycrystalline silicon wafer, and placed on a 70°C hot plate for heating and drying.

5. The surface enhanced Raman detection method for furfural in transformer oil based on Ti3C2Tx / AgNWs composite substrate according to claim 1, characterized in that: The specific preparation process of preparing furfural solutions dissolved in transformer oil of different concentrations is as follows: 1.5 ml of furfural is measured and dissolved in 1 L of transformer oil, and diluted according to a 2-fold concentration gradient to obtain furfural-transformer oil solutions with concentrations of 1740 mg / L, 870 mg / L, 435 mg / L, 217.5 mg / L, 108.8 mg / L, 54.4 mg / L, 27.2 mg / L, and 13.6 mg / L, respectively.

6. The surface enhanced Raman detection method for furfural in transformer oil based on Ti3C2Tx / AgNWs composite substrate according to claim 1, characterized in that: When the Raman spectrum data of the sample to be tested in the cuvette is collected based on the Raman spectrum detection platform, a spectrometer is used to test the Raman spectrum intensity of the sample to be tested. The specific detection conditions are as follows: the laser excitation wavelength is 532nm, the laser power is 30mV, the integration time is 1s, the number of integrations is 10, and 3 groups of Raman spectrum data at different points are collected for each sample, and the average value is taken as the final detection result.

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