Raman spectrum enhanced substrate for furfural detection, preparation method and detection method

Abstract

The invention relates to a Raman spectrum enhanced substrate for furfural detection, a preparation method and a detection method, in particular to the technical field of furfural detection.The Raman spectrum enhanced substrate for furfural detection comprises a carbon material, silver particles grow on the surface of the carbon material; 4-aminothiophenol is loaded on the surfaces of the silver particles; the particle size D90 of the silver particles is 5-15 nm; the mass ratio of the silver particles to the 4-aminothiophenol is (4-6): 1. According to the Raman spectrum enhanced substrate provided by the invention, by virtue of the synergistic cooperation of the carbon material, the silver particles and the 4-aminothiophenol, the substrate is easier to enrich target molecules, so that the detection sensitivity is higher, the low-concentration detection of furfural in transformer oil is realized, and the rapid detection requirement of the substrate is met.

Description

Technical Field

[0001] The present invention relates to the technical field of furfural detection, and particularly relates to a Raman spectroscopy enhancement substrate for furfural detection, a preparation method thereof, and a detection method, and more particularly relates to a Raman spectroscopy enhancement substrate for detecting furfural in transformer oil, a preparation method thereof, and a detection method. Background Art

[0002] At present, furfural, as one of the important characteristic parameters of oil-paper insulation aging, plays a key role in evaluating the aging state of transformers. DL / T596-1996 "Preventive Tests for Electric Power Equipment" stipulates that when the furfural content in mineral oil reaches 0.1 mg / L, the insulating paper is in a slightly aged state; when it reaches 0.5 mg / L, the insulating paper is in a moderately aged state; when the furfural content reaches 4 mg / L, the insulating paper is in a severely aged state. Accurately grasping the aging state of the oil-paper insulation of electrical equipment is not only of great significance for the safe, reliable, and economic operation of the power grid, but also one of the keys to ensuring the safe production of the power grid and realizing the efficient maintenance of electrical equipment.

[0003] Surface-enhanced Raman spectroscopy (SERS) technology can achieve fingerprint recognition of target molecules by detecting molecules (monolayers and sub-monolayers) adsorbed on the metal surface, and can also give the structural information of surface molecules. Therefore, in recent years, it has been widely used in the fields of analytical chemistry, archaeological culture, drug detection, environmental and pesticide residue detection, etc.

[0004] However, since the target molecules to be detected adsorbed on the SERS substrate are usually very complex, in addition, the uneven distribution of metal nanoparticles, the charge transfer between the metal and the molecules, etc. will all affect the final distribution of SERS hot spots and the intensity of Raman signals, which limits the application of surface-enhanced Raman spectroscopy technology in the detection of multiple aging characteristic substances dissolved in transformer oil. Therefore, in order to improve the high sensitivity and high consistency of SERS detection, researchers have tried to introduce metal materials on the substrate to construct a high-sensitivity SERS detection platform.

[0005] For example, CN115015213A discloses a method for surface-enhanced Raman detection of furfural in transformer oil based on a Ti3C2T x / AgNW s composite substrate, which includes the following steps: preparation of AgNW s solution, synthesis of Ti3C2T x two-dimensional nanosheet solution, preparation of Ti3C2T x / AgNW s composite substrate, and detection of furfural in transformer oil based on a Raman spectroscopy detection platform. By selecting the intensity of the Raman characteristic peak at 1705 cm -1 of the furfural molecule and using a least squares quantitative detection model, the furfural concentration in transformer oil is obtained.

[0006] CN118190904A discloses a Raman spectroscopy surface enhancement substrate for furfural detection and its preparation method, which relates to the technical field of detection. The Raman spectroscopy surface enhancement substrate is composed of a number of nanocolumns forming an array. The nanocolumns are manufactured by a femtosecond laser 3D printer. The diameter of the nanocolumns is 200 - 800 nm, and the surface of the nanocolumns is coated with a gold or silver coating.

[0007] However, due to the complex composition and low furfural content in operating transformer oil, the relative intensity of the Raman signal of furfural molecules dissolved in the oil is weak, and the requirement for detection sensitivity is high. The currently disclosed Raman spectroscopy surface enhancement materials for the detection of furfural in transformer oil still have the defects of low detection sensitivity and low detection accuracy, and the detection results are difficult to meet the power industry standards. Summary of the Invention

[0008] In view of the problems existing in the prior art, the purpose of the present invention is to provide a Raman spectroscopy enhancement substrate for furfural detection, its preparation method and detection method, so as to solve the defects of low detection sensitivity and low detection accuracy when the Raman spectroscopy surface enhancement material is used for the detection of furfural in transformer oil.

[0009] To achieve this purpose, the present invention adopts the following technical solutions:

[0010] In the first aspect, the present invention provides a Raman spectroscopy enhancement substrate for furfural detection, and the Raman spectroscopy enhancement substrate for furfural detection includes:

[0011] A carbon material, on the surface of which silver particles grow;

[0012] 4-aminothiophenol is loaded on the surface of the silver particles;

[0013] The particle size D90 of the silver particles is 5 - 15 nm;

[0014] The mass ratio of the silver particles to 4-aminothiophenol is (4 - 6):1.

[0015] The Raman spectroscopy enhancement substrate provided by the present invention, through the synergistic cooperation of the carbon material, silver particles and 4-aminothiophenol, makes the substrate easier to enrich the target molecules, thereby making the detection sensitivity higher, so as to realize the low-concentration detection of furfural in transformer oil and meet the rapid detection requirements of the substrate, and the lowest detection limit can reach 0.025 mg / L.

[0016] As a preferred technical solution of the present invention, the carbon material includes one or at least two combinations of carbon fiber, graphene or carbon nanotube.

[0017] In a second aspect, the present invention provides a method for preparing a Raman spectroscopy enhancement substrate for furfural detection as described in the first aspect, the preparation method comprising:

[0018] In-situ growing silver particles on the surface of the carbon material to obtain a carbon material-silver composite material;

[0019] Soaking the carbon material-silver composite material with 4-aminothiophenol to obtain a Raman spectroscopy enhancement substrate for furfural detection.

[0020] As a preferred technical solution of the present invention, the carbon material includes: a flexible carbon material.

[0021] Preferably, the carbon material is activated with an acid solution before in-situ growing silver particles.

[0022] Preferably, the acid solution includes: one or a combination of at least two of sulfuric acid, nitric acid or hydrochloric acid.

[0023] Preferably, the concentration of the acid solution is 1-3 mol / L.

[0024] Preferably, the activation temperature is 60-80 °C.

[0025] Preferably, the activation time is 20-40 min.

[0026] As a preferred technical solution of the present invention, the process of in-situ growing silver particles includes: immersing the carbon material in a silver-containing solution, and then dropping a reducing agent for growth.

[0027] As a preferred technical solution of the present invention, the concentration of the silver-containing solution is 0.05-0.12 mol / L.

[0028] Preferably, the solute of the silver-containing solution includes: a soluble silver salt.

[0029] Preferably, the volume ratio of the silver-containing solution to the reducing agent is (20-35):1.

[0030] Preferably, the concentration of the reducing agent is 0.05-0.1 mol / L.

[0031] Preferably, the reducing agent includes: sodium borohydride.

[0032] As a preferred technical solution of the present invention, the temperature of the solution when dropping the reducing agent is 40-50 °C.

[0033] Preferably, after dropping the reducing agent, the reaction is carried out for 1-1.2 h before growth.

[0034] Preferably, the growth temperature is 80-100 °C.

[0035] Preferably, the growth time ≥ 20 min.

[0036] As a preferred technical solution of the present invention, the 4-aminothiophenol immersion includes: immersing the carbon material-silver composite material in a 4-aminothiophenol solution, and then adding concentrated inorganic acid for immersion.

[0037] As a preferred technical solution of the present invention, the concentration of the 4-aminothiophenol solution is 0.1-1 mmol / L.

[0038] Preferably, the volume ratio of the 4-aminothiophenol solution to the concentrated inorganic acid is (9-11):1.

[0039] Preferably, the immersion time ≥ 10 min.

[0040] In a third aspect, the present invention provides a Raman spectroscopy detection method for furfural, and the Raman spectroscopy detection method includes:

[0041] Contacting a standard sample or a sample to be tested with the Raman spectroscopy enhancement substrate for furfural detection as described in the first aspect, and then performing Raman spectroscopy detection on the contacted Raman spectroscopy enhancement substrate for furfural detection to obtain the Raman spectrum of furfural.

[0042] Compared with the prior art solutions, the present invention has the following beneficial effects:

[0043] (1) The present invention can in-situ grow silver nanoparticles with controllable particle size on the surface of flexible carbon cloth to form a silver blanket coating layer.

[0044] (2) The present invention solves the problem that it is difficult to achieve high-sensitivity and rapid detection of furfural in mineral oil with traditional SERS substrates. By using the aptamer-modified SERS filter membrane technology, 4-ATP molecules are anchored on the surface of the carbon cloth-silver nanoparticles, thereby realizing the enrichment of furfural in mineral oil. The lowest detection limit can reach 0.025 mg / L, and the detection result fully meets the detection standard of furfural after mild aging in the power industry.

[0045] (3) The preparation process of the present invention is green and environmentally friendly, can be mass-produced, the synthesized materials have high sensitivity and good consistency, and are suitable for multi-parameter detection of multiple aging characteristic substances in transformer oil. Description of the Drawings

[0046] Figure 1 is a low-magnification micrograph of the Raman spectroscopy enhancement substrate for furfural detection obtained in Example 1 of the present invention;

[0047] Figure 2 is a high-magnification micrograph of the Raman spectroscopy enhancement substrate for furfural detection obtained in Example 1 of the present invention;

[0048] Figure 3 This is the spectrogram of the Raman spectra of furfural in transformer oils with different concentrations detected by the Raman spectroscopy enhanced substrate obtained in Example 1 of the present invention for furfural detection.

[0049] The present invention will be further described in detail below. However, the following examples are merely simple examples of the present invention and do not represent or limit the scope of the claimed protection of the present invention. The scope of protection of the present invention shall be subject to the claims. Specific embodiments

[0050] To better illustrate the present invention and facilitate understanding of the technical solution of the present invention, typical but non-limiting embodiments of the present invention are as follows:

[0051] This embodiment provides a Raman spectroscopy enhanced substrate for furfural detection, and the Raman spectroscopy enhanced substrate for furfural detection includes:

[0052] A carbon material, on the surface of which silver particles are grown and 4-aminothiophenol is loaded;

[0053] A carbon material, on the surface of which silver particles are grown;

[0054] 4-Aminothiophenol is loaded on the surface of the silver particles;

[0055] The particle size D90 of the silver particles is 5 - 15 nm;

[0056] The mass ratio of the silver particles to 4-aminothiophenol is (4 - 6):1.

[0057] Among them, the carbon material includes one or at least two combinations of carbon fiber, graphene or carbon nanotube.

[0058] Among them, the particle size D90 of the silver particles is 5 - 15 nm. For example, it can be 5 nm, 6 nm, 7 nm, 8 nm, 9 nm, 10 nm, 11 nm, 12 nm, 13 nm, 14 nm or 15 nm, etc., but is not limited to the listed values, and other unlisted values within this range also meet the requirements.

[0059] Among them, the mass ratio of the silver particles to 4-aminothiophenol is (4 - 6):1. For example, it can be 4:1, 4.2:1, 4.4:1, 4.6:1, 4.8:1, 5:1, 5.2:1, 5.4:1, 5.6:1, 5.8:1 or 6:1, etc., but is not limited to the listed values, and other unlisted values within this range also meet the requirements.

[0060] Furthermore, this embodiment provides a preparation method of the aforementioned Raman spectroscopy enhanced substrate for furfural detection, which is specifically as follows:

[0061] In-situ growth of silver particles on the surface of carbon materials to obtain carbon material-silver composites;

[0062] Soak the carbon material-silver composites in 4-aminothiophenol to obtain a Raman spectroscopy enhancement substrate for furfural detection.

[0063] Among them, the carbon materials include: carbon materials such as flexible carbon materials, such as carbon fiber cloth (with a thickness of 100-400 μm and a porosity of 60-90%), or other shaped carbon materials, such as flake activated carbon, etc.

[0064] Among them, before in-situ growth of silver particles on the carbon materials used, cleaning can be selected to remove impurities, oil stains and oxide layers on the surface of the carbon cloth. An exemplary cleaning process is as follows: carry out alcohol washing and / or ketone washing processes with or without ultrasound. The specific process parameters can be confirmed and designed according to the cleaning requirements and the conventional cleaning processes in the art. For example, place the carbon material in an ethanol solution and perform ultrasonic treatment for 10-20 minutes. After taking out the cleaned carbon material, place it in a drying oven at 50-70 °C for drying for ≥24 hours. Then place it in an acetone solution and perform ultrasonic cleaning for 10-20 minutes. After taking out the cleaned carbon material, place it in a drying oven at 50-70 °C for drying for ≥24 hours and take it out for standby.

[0065] Among them, the carbon materials are activated with an acid solution before in-situ growth of silver particles.

[0066] Among them, the acid solution includes: one or a combination of at least two of sulfuric acid, nitric acid or hydrochloric acid.

[0067] Among them, the concentration of the acid solution is 1-3 mol / L. For example, it can be 1 mol / L, 1.2 mol / L, 1.4 mol / L, 1.6 mol / L, 1.8 mol / L, 2 mol / L, 2.2 mol / L, 2.4 mol / L, 2.6 mol / L, 2.8 mol / L or 3 mol / L, etc., but not limited to the listed values. Other unlisted values within this range also meet the requirements.

[0068] Among them, the activation temperature is 60-80 °C. For example, it can be 60 °C, 62 °C, 64 °C, 66 °C, 68 °C, 70 °C, 72 °C, 74 °C, 76 °C, 78 °C or 80 °C, etc., but not limited to the listed values. Other unlisted values within this range also meet the requirements.

[0069] Among them, the activation time is 20-40 minutes. For example, it can be 20 minutes, 22 minutes, 24 minutes, 26 minutes, 28 minutes, 30 minutes, 32 minutes, 34 minutes, 36 minutes, 38 minutes or 40 minutes, etc., but not limited to the listed values. Other unlisted values within this range also meet the requirements.

[0070] Among them, the process of in-situ growing silver particles includes: immersing the carbon material in a silver-containing solution, and then dropping a reducing agent for growth.

[0071] Among them, the concentration of the silver-containing solution is 0.05 - 0.12 mol / L. For example, it can be 0.05 mol / L, 0.055 mol / L, 0.06 mol / L, 0.065 mol / L, 0.07 mol / L, 0.075 mol / L, 0.08 mol / L, 0.085 mol / L, 0.09 mol / L, 0.095 mol / L, 0.1 mol / L, 0.105 mol / L, 0.11 mol / L, 0.115 mol / L or 0.12 mol / L, etc., but not limited to the listed values, and other unlisted values within this range also meet the requirements.

[0072] Among them, the solute of the silver-containing solution includes: soluble silver salts.

[0073] In the present invention, the soluble silver salt used can be selected as silver nitrate, etc.

[0074] Among them, the volume ratio of the silver-containing solution to the reducing agent is (20 - 35):1. For example, it can be 20:1, 22:1, 24:1, 26:1, 28:1, 30:1, 31:1, 32:1, 33:1, 34:1 or 35:1, etc., but not limited to the listed values, and other unlisted values within this range also meet the requirements.

[0075] Among them, the concentration of the reducing agent is 0.05 - 0.1 mol / L. For example, it can be 0.05 mol / L, 0.055 mol / L, 0.06 mol / L, 0.065 mol / L, 0.07 mol / L, 0.075 mol / L, 0.08 mol / L, 0.085 mol / L, 0.09 mol / L, 0.095 mol / L or 0.1 mol / L, etc., but not limited to the listed values, and other unlisted values within this range also meet the requirements.

[0076] Among them, the reducing agent includes: sodium borohydride.

[0077] Among them, the temperature of the solution when dropping the reducing agent is 40 - 50 °C. For example, it can be 40 °C, 41 °C, 42 °C, 43 °C, 44 °C, 45 °C, 46 °C, 47 °C, 48 °C, 49 °C or 50 °C, etc., but not limited to the listed values, and other unlisted values within this range also meet the requirements.

[0078] Among them, growth is carried out after reacting for 1 - 1.2 h after dropping the reducing agent. For example, it can be 1 h, 1.02 h, 1.04 h, 1.06 h, 1.08 h, 1.1 h, 1.12 h, 1.14 h, 1.16 h, 1.18 h or 1.2 h, etc., but not limited to the listed values. Other unlisted values within this range also meet the requirements.

[0079] Among them, the temperature of the growth is 80 - 100 °C. For example, it can be 80 °C, 82 °C, 84 °C, 86 °C, 88 °C, 90 °C, 92 °C, 94 °C, 96 °C, 98 °C or 100 °C, etc., but not limited to the listed values. Other unlisted values within this range also meet the requirements.

[0080] Among them, the growth time ≥ 20 min. For example, it can be 20 min, 30 min, 40 min, 50 min, 60 min, 70 min, 80 min or 90 min, etc., but not limited to the listed values. Other unlisted values within this range also meet the requirements.

[0081] Among them, the 4-aminothiophenol soaking includes: immersing the carbon material - silver composite material in a 4-aminothiophenol solution, and then adding concentrated inorganic acid for soaking.

[0082] Among them, the concentration of the 4-aminothiophenol solution is 0.1 - 1 mmol / L. For example, it can be 0.1 mmol / L, 0.2 mmol / L, 0.3 mmol / L, 0.4 mmol / L, 0.5 mmol / L, 0.6 mmol / L, 0.7 mmol / L, 0.8 mmol / L, 0.9 mmol / L or 1 mmol / L, etc., but not limited to the listed values. Other unlisted values within this range also meet the requirements.

[0083] In the present invention, the concentration of the 4-aminothiophenol solution is adjusted by using solvents such as water or alcohol.

[0084] Among them, the volume ratio of the 4-aminothiophenol solution to the concentrated inorganic acid is (9 - 11):1. For example, it can be 9:1, 9.2:1, 9.4:1, 9.6:1, 9.8:1, 10:1, 10.2:1, 10.4:1, 10.6:1, 10.8:1 or 11:1, etc., but not limited to the listed values. Other unlisted values within this range also meet the requirements.

[0085] Among them, the soaking time ≥ 10 min. For example, it can be 10 min, 20 min, 30 min, 40 min, 50 min, 60 min, 70 min, 80 min or 90 min, etc., but not limited to the listed values. Other unlisted values within this range also meet the requirements.

[0086] In the present invention, the inorganic concentrated acids used include concentrated sulfuric acid (mass concentration ≥ 93%), concentrated nitric acid (mass concentration ≥ 86%), concentrated hydrochloric acid (mass concentration 36 - 38%), etc.

[0087] Furthermore, this embodiment provides a Raman spectroscopy detection method for furfural. The Raman spectroscopy detection method includes:

[0088] Contact-treat the standard sample or the sample to be tested with the aforementioned Raman spectroscopy enhancement substrate for furfural detection, and then perform Raman spectroscopy detection on the contact-treated Raman spectroscopy enhancement substrate for furfural detection to obtain the Raman spectrum of furfural.

[0089] In the present invention, the contact treatment refers to that the sample passes through the Raman spectroscopy enhancement substrate in a filtering manner, or the sample contacts with the Raman spectroscopy enhancement substrate in an immersion manner.

[0090] Exemplarily, during the detection process, the sampling volume of the oil sample is 2 mL, the concentration of the oil sample is 0.01 - 100 mg / L, the contact time between the oil sample and the Raman spectroscopy enhancement substrate for furfural detection is 100 - 150 s, the excitation light wavelength is 785 nm, the laser power is 50 mW, the integration time is 1 s, the number of times is 10 times, the slit width is 10 μm, and the 1200 / 500 nm type grating is selected.

[0091] Furthermore, by combining the relevant characteristic peaks of the Raman spectra of furfural at different concentrations, a concentration-characteristic peak parameter calibration line is obtained through linear fitting. Then, by measuring the Raman spectrum of the sample and corresponding the measured and calculated characteristic peak parameters to the calibration line, the detection of the furfural concentration can be achieved.

[0092] Furthermore, in order to illustrate the good detection and analysis effect that the Raman spectroscopy enhancement substrate provided by the present invention can achieve for furfural, the following practical examples are used for exemplary description, specifically as follows:

[0093] The carbon cloth used in the following examples has a thickness of 350 μm and is purchased from Jiangsu Xianfeng Nano Technology Co., Ltd.

[0094] The disposable needle-type nanofilter used in the following examples has a diameter of 1 cm, and the disposable syringe specification is 5 mL, both of which are purchased from Xianfeng Nano Technology Co., Ltd.

[0095] Example 1

[0096] This embodiment provides a Raman spectroscopy enhancement substrate for furfural detection. The preparation process is as follows:

[0097] (1) Pretreat the flexible carbon cloth: Cut a circular flexible carbon cloth with a diameter of 1 cm, place the flexible carbon cloth in ethanol, perform ultrasonic cleaning for 15 min, then take it out and dry it in an oven at 60 °C for 24 h; Place the flexible carbon cloth treated with ethanol in acetone, perform ultrasonic cleaning for 15 min, take out the cleaned carbon cloth and dry it in an oven at 60 °C for 24 h and take it out for standby; The purpose of ultrasonic cleaning with ethanol solution is to remove impurities on the surface of the carbon cloth; The purpose of cleaning with acetone solution is to remove oil stains and oxide layers on the surface of the carbon cloth; Activate the obtained carbon cloth with nitric acid (2 mol / L) at 70 °C for 30 min;

[0098] (2) Transfer the activated carbon cloth to a 100 mL round-bottom flask, add 40 mL of deionized water, heat it to 50 °C, stir with a glass stirring rod for 10 min, add 0.04 g of silver nitrate and heat it to 40 °C, then add 1.5 mL of 0.05 mol / L sodium borohydride solution, and keep stirring at 50 °C for 1.2 h, then grow for 25 min in a water bath environment at 85 °C, take out the carbon cloth, and perform drying treatment at 60 °C to obtain the CC-AgNPs material;

[0099] (3) Place the CC-AgNPs material in 2 mL of 0.8 mmol / L 4-aminothiophenol ethanol solution, and drop in 0.22 mL of 98% sulfuric acid, stir evenly and soak for 15 min;

[0100] (4) Take out the soaked composite carbon cloth, and perform drying treatment at 60 °C to obtain the 4-ATP@CC-AgNPs substrate SERS filter membrane.

[0101] Observe the morphology of the prepared flexible 4-ATP-CC-AgNPs SERS filter membrane by scanning electron microscope, as Figure 1 and Figure 2 shown, Figure 1 and Figure 2 correspond to the SEM photos under low-power and high-power microscopes respectively. It can be seen from the figure that the AgNPs in-situ grown on the surface of the carbon cloth have good uniformity, high density, and many nano-gaps, that is, they have the basis for forming Raman hot spots.

[0102] Use the carbon cloth-silver blanket composite SERS filter membrane obtained in Example 1 for the detection of furfural in transformer oil, specifically as follows:

[0103] (1) Place the carbon cloth-silver blanket composite SERS filter membrane prepared in Example 1 in a disposable needle-type nanofilter with a matching diameter, and install it on a 5 mL disposable syringe;

[0104] (2) Use a pipette to prepare furfural-transformer oil solutions with different concentration gradients (the furfural concentrations are 0.01 mg / L, 0.025 mg / L, 0.05 mg / L, 0.1 mg / L, 0.5 mg / L, 1 mg / L, 5 mg / L, 10 mg / L, and 50 mg / L respectively), and heat the oil samples to 60 °C;

[0105] (3) Take 2 mL of the furfural-transformer oil samples with the above gradient concentrations and transfer them to a syringe respectively. Push the piston handle, and the standard oil sample passes through the carbon cloth-silver blanket composite SERS filter membrane in a disposable needle-type nanofilter, control the passing time to be about 120 s, and flow out along the needle tip;

[0106] (4) Take out the carbon cloth-silver blanket composite SERS filter membrane through which the oil sample has passed, and place it under a portable Raman spectrometer to detect its SERS signal; analyze and compare the obtained SERS signals to obtain the Raman spectrum of furfural varying with concentration;

[0107] In this embodiment, the excitation light wavelength for Raman spectroscopy research and detection is 785 nm, the laser power is 50 mW, the integration time is 1 s, the number of times is 10 times, the slit width is 10 μm, and a 1200 / 500 nm type grating is selected;

[0108] The obtained Raman spectrum is as Figure 3 shown. It can be seen from the figure that as the furfural concentration decreases, the Raman characteristic peak of furfural at 1658 cm -1 shows a gradually decreasing trend until the characteristic peak is submerged when the furfural concentration is 0.01 mg / L. Therefore, the lowest detection limit is 0.025 mg / L.

[0109] Example 2

[0110] The difference from Example 1 is only that the preparation process of the Raman spectroscopy enhancement substrate for furfural detection is as follows:

[0111] (1) Pretreat the flexible carbon cloth: Cut a circular flexible carbon cloth with a diameter of 1 cm, place the flexible carbon cloth in ethanol, perform ultrasonic cleaning for 15 min, and then take it out and dry it in a drying oven at 60 °C for 24 h; place the flexible carbon cloth treated with ethanol in acetone, perform ultrasonic cleaning for 15 min, take out the cleaned carbon cloth and dry it in a drying oven at 60 °C for 24 h and then take it out for standby; the purpose of using ethanol solution for ultrasonic cleaning is to remove impurities on the surface of the carbon cloth; the purpose of using acetone solution for cleaning is to remove oil stains and oxide layers on the surface of the carbon cloth; activate the obtained carbon cloth with nitric acid (1 mol / L) at 60 °C for 40 min;

[0112] (2) Transfer the activated carbon cloth to a 100 mL round-bottom flask, add 40 mL of deionized water, heat up to 40 °C, stir with a glass stirring rod for 10 min, add 0.68 g of silver nitrate, and then slowly add 2 mL of 0.05 mol / L sodium borohydride solution. React in a water bath at 40 °C for 1 h, then heat up to 85 °C and keep stirring for 60 min. Take out the carbon cloth and dry it at 60 °C to obtain the CC-AgNPs material;

[0113] (3) Place the CC-AgNPs material in 2 mL of 1 mmol / L 4-aminothiophenol ethanol solution, and drop in 0.22 mL of 98% sulfuric acid. After stirring evenly, soak for 20 min;

[0114] (4) Take out the soaked composite carbon cloth and dry it at 60 °C to obtain the 4-ATP@CC-AgNPs substrate SERS filter membrane.

[0115] Example 3

[0116] The difference from Example 1 is only that the preparation process of the Raman spectroscopy enhancement substrate for furfural detection is as follows:

[0117] (1) Pretreat the flexible carbon cloth: Cut a circular flexible carbon cloth with a diameter of 1 cm, place the flexible carbon cloth in ethanol, perform ultrasonic cleaning for 15 min, and then take it out and dry it in a drying oven at 60 °C for 24 h; Place the ethanol-treated flexible carbon cloth in acetone, perform ultrasonic cleaning for 15 min, take out the cleaned carbon cloth and dry it in a drying oven at 60 °C for 24 h and then take it out for standby; The purpose of ultrasonic cleaning with ethanol solution is to remove impurities on the surface of the carbon cloth; The purpose of cleaning with acetone solution is to remove oil stains and oxide layers on the surface of the carbon cloth; Activate the obtained carbon cloth with nitric acid (3 mol / L) at 80 °C for 20 min;

[0118] (2) Transfer the activated carbon cloth to a 100 mL round-bottom flask, add 40 mL of deionized water, heat up to 50 °C, stir with a glass stirring rod for 10 min, add 0.038 g of silver nitrate and heat up to 50 °C, then add 1.2 mL of 0.1 mol / L sodium borohydride solution, and keep stirring at 50 °C for 1 h. Then grow in a water bath at 85 °C for 25 min. Take out the carbon cloth and dry it at 60 °C to obtain the CC-AgNPs material;

[0119] (3) Place the CC-AgNPs material in 2 mL of 0.8 mmol / L 4-aminothiophenol ethanol solution, and drop in 0.22 mL of 98% sulfuric acid. After stirring evenly, soak for 10 min;

[0120] (4) Take out the soaked composite carbon cloth and dry it at 60 °C to obtain the 4-ATP@CC-AgNPs substrate SERS filter membrane.

[0121] Comparative Example 1

[0122] The difference from Example 1 is only that the grown silver material is replaced with an equal amount of gold material.

[0123] Comparative Example 2

[0124] The difference from Example 1 is only that the flexible carbon cloth is replaced with a glass substrate.

[0125] Comparative Example 3

[0126] The difference from Example 1 is only that no silver material is set.

[0127] Comparative Example 4

[0128] The difference from Example 1 is only that the soaking in the 4-aminothiophenol ethanol solution is not carried out.

[0129] The minimum detection line results of Examples 1-3 and Comparative Examples 1-4 are shown in Table 1 below.

[0130] Table 1

[0131]

[0132]

[0133] In summary, it can be seen that the detection results of the Raman spectroscopy enhancement substrate provided by the present invention for furfural detection can fully meet the detection standards of furfural after mild aging in the power industry.

[0134] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0135] In addition, it should be noted that, among the various specific technical features described in the above specific embodiments, they can be combined in any suitable manner without conflict. To avoid unnecessary repetition, the present invention will not separately describe various possible combination methods.

[0136] In addition, any combination can be made between various different embodiments of the present invention as long as it does not violate the idea of the present invention, and it should also be regarded as the content disclosed by the present invention.

Claims

1. A Raman spectroscopy enhancement substrate for furfural detection, characterized in that, The Raman spectroscopy enhancement substrate for furfural detection includes: a carbon material, on the surface of which silver particles are grown; 4-aminothiophenol is loaded on the surface of the silver particles; the particle size D90 of the silver particles is 5-15 nm; the mass ratio of the silver particles to 4-aminothiophenol is (4-6):

1.

2. The Raman spectroscopy enhancement substrate for furfural detection according to claim 1, wherein The carbon material includes: one or a combination of at least two of carbon fiber, graphene or carbon nanotube.

3. A method for preparing a Raman spectroscopy enhancement substrate for furfural detection as described in claim 1 or 2, characterized in that, The preparation method includes: growing silver particles in-situ on the surface of the carbon material to obtain a carbon material-silver composite; immersing the carbon material-silver composite in 4-aminothiophenol to obtain a Raman spectroscopy enhancement substrate for furfural detection.

4. The preparation method according to claim 3, characterized in that, The carbon material includes: a flexible carbon material; Preferably, the carbon material is activated with an acid solution before growing silver particles in-situ; Preferably, the acid solution includes: one or a combination of at least two of sulfuric acid, nitric acid or hydrochloric acid; Preferably, the concentration of the acid solution is 1-3 mol / L; Preferably, the activation temperature is 60-80 °C; Preferably, the activation time is 20-40 min.

5. The preparation method according to claim 3, characterized in that, The process of growing silver particles in-situ includes: immersing the carbon material in a silver-containing solution, and then dropping a reducing agent for growth.

6. The preparation method according to claim 5, wherein The concentration of the silver-containing solution is 0.05-0.12 mol / L; Preferably, the solute of the silver-containing solution includes: a soluble silver salt; Preferably, the volume ratio of the silver-containing solution to the reducing agent is (20-35):1; Preferably, the concentration of the reducing agent is 0.05-0.1 mol / L; Preferably, the reducing agent includes: sodium borohydride.

7. The preparation method according to claim 5 or 6, characterized in that, The temperature of the solution when dropping the reducing agent is 40-50 °C; Preferably, after dropping the reducing agent, the reaction is carried out for 1-1.2 h before growth; Preferably, the growth temperature is 80-100 °C; Preferably, the growth time is ≥20 min.

8. The preparation method according to claim 3, characterized in that, The 4-aminothiophenol immersion includes: immersing the carbon material-silver composite in a 4-aminothiophenol solution, and then adding concentrated inorganic acid for immersion.

9. The preparation method according to claim 8, characterized in that, The concentration of the 4-aminothiophenol solution is 0.1-1 mmol / L; Preferably, the volume ratio of the 4-aminothiophenol solution to the concentrated inorganic acid is (9-11):1; Preferably, the immersion time is ≥10 min.

10. A Raman spectroscopy detection method for furfural, characterized in that, The Raman spectroscopy detection method includes: Contacting a standard sample or a sample to be tested with the Raman spectroscopy enhancement substrate for furfural detection as described in claim 1 or 2, and then performing Raman spectroscopy detection on the contacted Raman spectroscopy enhancement substrate for furfural detection to obtain the Raman spectrum of furfural.

Images