Method for on-line detection of hydrogen peroxide concentration based on surface enhanced Raman spectroscopy

Abstract

The invention discloses a method for online detection of hydrogen peroxide concentration based on surface enhanced Raman spectroscopy. The method comprises the following steps: preparing an Ag-COF-COOH substrate; a 4-MBA solution is mixed with the Ag-COF-COOH substrate, and a mixed detection solution is obtained; introducing hydrogen peroxide into the mixed detection solution to obtain a reaction mixed solution; and performing real-time Raman spectrum acquisition on the reaction mixed solution by using a Raman spectrometer to obtain a Raman characteristic peak. According to the invention, the problems of weak Raman signal of hydrogen peroxide, complexity of a traditional detection method and the like are solved through the surface enhanced Raman spectrum technology, the concentration change of hydrogen peroxide can be accurately monitored in real time, the detection efficiency is improved, and high sensitivity and high selectivity are especially suitable for application scenes with high requirements on hydrogen peroxide concentration.

Description

Technical Field

[0001] The invention relates to the field of chemical detection, and in particular to a method for online detection of hydrogen peroxide concentration based on surface enhanced Raman spectroscopy. Background Art

[0002] In the prior art, the detection method for hydrogen peroxide concentration is relatively weak because the Raman signal of hydrogen peroxide itself is relatively weak and the Raman characteristic peak in the solution is not obvious, which makes its quantitative analysis relatively complicated. In order to accurately analyze the concentration of hydrogen peroxide, the current Raman method usually needs to rely on contrast signals, internal standard substances or multiple calibration methods, which further increases the complexity of the operation. Other spectral methods, such as UV-Vis and fluorescence spectroscopy, have high sensitivity for detecting hydrogen peroxide, but poor selectivity and are easily affected by interfering substances. Near-infrared FTIR has high resolution, but low sensitivity and limited dynamic range, and is difficult to detect when hydrogen peroxide is trace. Summary of the invention

[0003] In order to overcome the defects in the prior art, an embodiment of the present invention provides a method for online detection of hydrogen peroxide concentration based on surface enhanced Raman spectroscopy, which is used to solve one or more of the above problems.

[0004] The embodiment of the present application discloses: a method for online detection of hydrogen peroxide concentration based on surface enhanced Raman spectroscopy, comprising the following steps: preparing an Ag-COF-COOH substrate; mixing a 4-MBA solution with the Ag-COF-COOH substrate to obtain a mixed detection liquid; passing hydrogen peroxide into the mixed detection liquid to obtain a reaction mixture; and using a Raman spectrometer to collect real-time Raman spectra of the reaction mixture to obtain Raman characteristic peaks.

[0005] Furthermore, in the step of "preparing an Ag-COF-COOH substrate", the following steps are included: preparing COF-COOH powder; adding silver nitrate solid and the COF-COOH powder into a conical flask for incubation to obtain a reaction product; and adding sodium citrate solution dropwise to the reaction product under a high temperature environment to obtain the yellow-green Ag-COF-COOH substrate.

[0006] Furthermore, in the step of "preparing COF-COOH powder", the following steps are included: adding triformyl chloride to ethyl acetate solution to obtain triformyl chloride-ethyl acetate solution; adding the triformyl chloride-ethyl acetate solution into a round-bottom flask; dissolving p-phenylenediamine in the ethyl acetate solution, and adding dropwise into the round-bottom flask with a dropper, stirring in an ice bath environment to obtain a reaction system; reacting the reaction system at room temperature to obtain and filter and collect a yellow powder; washing the yellow powder with ethanol and an ultrapure water solution; drying overnight in a vacuum drying oven at 80°C to 100°C and evaporating excess ethanol and water to obtain the COF-COOH powder.

[0007] Furthermore, in the step of "washing the yellow powder with ethanol and ultrapure water solution", the ethanol and ultrapure water solution are centrifuged at a speed of 6000-12000 rpm for 8-10 minutes and centrifuged 3-6 times.

[0008] Further, in the step of "adding triformyl chloride to ethyl acetate solution to obtain triformyl chloride-ethyl acetate solution", the triformyl chloride is slowly added to the ethyl acetate solution and stirred until completely dissolved to obtain the triformyl chloride-ethyl acetate solution.

[0009] Furthermore, in the step of "using a Raman spectrometer to collect real-time Raman spectra of the reaction mixture to obtain Raman characteristic peaks", the following steps are included: removing the baseline and SG filtering noise from the collected Raman spectrum data; testing a hydrogen peroxide solution with a known concentration at different concentrations; and then selecting the characteristic peak data of 4-MBA at a specific Raman wavenumber, and obtaining a fitting equation for the hydrogen peroxide concentration by the least squares method.

[0010] Furthermore, in the step of "using a Raman spectrometer to collect real-time Raman spectra of the reaction mixture to obtain Raman characteristic peaks", the laser wavelength of the Raman spectrometer is 785nm-795nm, the laser power is 100mW-500mW, and the spectrum collection range is 500cm -1 ~3200cm -1 , the spectral resolution is adjusted to 2cm -1 ~8cm -1 , the acquisition time is set to 3s-5s.

[0011] Furthermore, it comprises: a reaction pool, in which the 4-MBA solution and the Ag-COF-COOH substrate are located; a circulation pool, which is connected to the reaction pool via a peristaltic pump, and has a detection area inside the circulation pool through which the solution can flow evenly, and the detection probe of the Raman spectrometer is fixed in the detection area of ​​the circulation pool.

[0012] Furthermore, it also includes a flow passage, wherein the flow passage is used to circulate the hydrogen peroxide, the flow passage has a main passage and a bypass, and the bypass is connected to the reaction tank.

[0013] Furthermore, after the hydrogen peroxide in the reaction pool reacts with the 4-MBA, the peristaltic pump allows the reaction mixture to enter the circulation pool at a flow rate of 0.1 mL / min-0.5 mL / min.

[0014] The beneficial effects of the present invention are as follows:

[0015] 1. Surface enhanced Raman spectroscopy technology overcomes the problems of weak hydrogen peroxide Raman signal and complex traditional detection methods. It can monitor the changes in hydrogen peroxide concentration in real time and accurately, and improve the detection efficiency. Its high sensitivity and high selectivity are especially suitable for application scenarios with high requirements for hydrogen peroxide concentration.

[0016] 2. The detection sensitivity is high and can sensitively reflect the changes in hydrogen peroxide concentration.

[0017] 3. Simplifies the Raman analysis process and reduces the reliance on contrast signals and calibration steps.

[0018] In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are specifically cited below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0020] Figure 1 is a flow chart of a method for online detection of hydrogen peroxide concentration based on surface enhanced Raman spectroscopy in an embodiment of the present invention;

[0021] Figure 2 Schematic diagram of the positional relationship of detection devices used in a method for online detection of hydrogen peroxide concentration based on surface enhanced Raman spectroscopy in an embodiment of the present invention;

[0022] Figure 3 It is a spectrum table for detecting the concentration gradient of hydrogen peroxide;

[0023] Figure 4 It is the hydrogen peroxide concentration gradient calibration curve table.

[0024] The figure numbers of the above figures are: 1, reaction cell; 2, circulation cell; 3, peristaltic pump; 4, Raman spectrometer; 5, flow path; 51, main path; 52, bypass. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] like Figure 1 to Figure 2 As shown, a method for online detection of hydrogen peroxide concentration based on surface enhanced Raman spectroscopy in this embodiment includes the following steps:

[0027] Ag-COF-COOH substrates were prepared, which could act as nanozymes with peroxidase-like properties, thereby subsequently catalyzing the decomposition of hydrogen peroxide to produce hydroxyl radicals (·OH).

[0028] The 4-MBA solution is mixed with the Ag-COF-COOH substrate to obtain a mixed detection solution. The hydroxyl radical (·OH) generated by the reaction of the Ag-COF-COOH substrate with hydrogen peroxide has high reactivity, while the sulfhydryl group (-SH) in 4-MBA is easily oxidized.

[0029] Hydrogen peroxide is introduced into the mixed detection solution to obtain a reaction mixture.

[0030] The Raman spectrometer 4 is used to collect the real-time Raman spectrum of the reaction mixture to obtain the Raman characteristic peak. 4-MBA, i.e. 4-mercaptobenzoic acid, is used as a Raman signal molecule, and its reaction can be sensitively monitored by Raman enhanced signal (SERS), thereby indirectly measuring the concentration of hydrogen peroxide.

[0031] Specifically, in the step of "preparing the Ag-COF-COOH substrate", the following steps are included: preparing COF-COOH powder. Adding silver nitrate solid and the COF-COOH powder into a conical flask for incubation to obtain a reaction product. Adding sodium citrate solution dropwise to the reaction product under a high temperature environment to obtain the yellow-green Ag-COF-COOH substrate.

[0032] Specifically, in the step of "preparing COF-COOH powder", the following steps are included: adding triformyl chloride to ethyl acetate solution to obtain triformyl chloride-ethyl acetate solution. Adding the triformyl chloride-ethyl acetate solution to a round-bottom flask. Dissolving p-phenylenediamine in ethyl acetate solution and adding dropwise to the round-bottom flask with a dropper, stirring under an ice bath environment to obtain a reaction system. Reacting the reaction system under normal temperature environment to obtain and filter and collect a yellow powder. Washing the yellow powder with ethanol and ultrapure water solution. Drying overnight at 80° C. to 100° C. in a vacuum drying oven and evaporating excess ethanol and water to obtain the COF-COOH powder.

[0033] Specifically, in the step of "washing the yellow powder with ethanol and ultrapure water solution", the ethanol and ultrapure water solution are centrifuged at a speed of 6000-12000 rpm for 8-10 minutes and centrifuged 3-6 times, so that the yellow powder has a better washing effect, thereby improving the purity of the obtained COF-COOH powder.

[0034] Specifically, in the step of "adding triformyl chloride to ethyl acetate solution to obtain triformyl chloride-ethyl acetate solution", the triformyl chloride is slowly added to the ethyl acetate solution and stirred until completely dissolved to obtain the triformyl chloride-ethyl acetate solution. Thus, the triformyl chloride can be completely dissolved in the ethyl acetate solution.

[0035] Specifically, in the step of "using Raman spectrometer 4 to collect real-time Raman spectra of the reaction mixture to obtain Raman characteristic peaks", the following steps are included: the collected Raman spectrum data is subjected to baseline removal and SG filtering and noise removal processing, so as to obtain more accurate Raman spectrum data. A hydrogen peroxide solution of known concentration is tested at different concentrations, so as to conveniently obtain Raman spectrum data at different concentrations. Then, the characteristic peak data of 4-MBA at a specific Raman wave number is selected, and the fitting equation of hydrogen peroxide concentration is obtained by the least squares method, so as to establish a linear calibration curve between hydrogen peroxide concentration and vibration peak intensity, and then the corresponding hydrogen peroxide concentration is obtained by obtaining the vibration peak.

[0036] Specifically, in the step of "using a Raman spectrometer 4 to collect real-time Raman spectra of the reaction mixture to obtain Raman characteristic peaks", the laser wavelength of the Raman spectrometer 4 is 785nm-795nm, the laser power is 100mW-500mW, and the spectrum collection range is 500cm –1 ~3200cm -1 , the spectral resolution is adjusted to 2cm -1 ~8cm -1, the acquisition time is set to 3s-5s. Thus, the Raman spectrometer 4 can have a better acquisition effect during the real-time Raman spectrum acquisition process.

[0037] Specifically, it comprises: a reaction tank 1, wherein the 4-MBA solution and the Ag-COF-COOH substrate are located in the reaction tank 1, so that the reaction tank 1 accommodates the 4-MBA solution and the Ag-COF-COOH substrate.

[0038] The circulation pool 2 is connected to the reaction pool 1 through a peristaltic pump 3, so that the solution in the reaction pool 1 flows into the circulation pool 2 at a fixed flow rate through the peristaltic pump 3. The circulation pool 2 has a detection area inside that allows the solution to flow evenly. The detection probe of the Raman spectrometer 4 is fixed in the detection area of ​​the circulation pool 2, so that the Raman spectrometer 4 can detect the solution in the circulation pool 2.

[0039] Specifically, it also includes a flow passage 5, the flow passage 5 is used to circulate the hydrogen peroxide, the flow passage 5 has a main passage 51 and a bypass passage 52, and the bypass passage 52 is connected to the reaction pool 1. Thus, the hydrogen peroxide in the main passage 51 of the flow passage 5 can flow normally, while the hydrogen peroxide in the bypass passage 52 can react with the 4-MBA solution and the Ag-COF-COOH substrate in the reaction pool 1, and the reacted solution can enter the circulation pool 2 under the action of the peristaltic pump 3 and be detected by the Raman spectrometer 4.

[0040] Specifically, after the hydrogen peroxide in the reaction pool 1 reacts with the 4-MBA, the peristaltic pump 3 allows the reaction mixture to enter the circulation pool 2 at a flow rate of 0.1 mL / min-0.5 mL / min, so that the reaction mixture entering the circulation pool 2 can have a more appropriate flow rate, thereby improving the detection accuracy of the Raman spectrometer 4.

[0041] The present invention is described in detail below in conjunction with embodiments:

[0042] Example 1: Preparation of Ag-COF-COOH substrate

[0043] Accurately weigh 1.59g of triformyl chloride, slowly add it to 45mL of ethyl acetate solution, stir until completely dissolved, and obtain triformyl chloride-ethyl acetate solution. Take another 0.45g of p-phenylenediamine and dissolve it in 15mL of ethyl acetate solution to prepare a p-phenylenediamine solution. Transfer the triformyl chloride-ethyl acetate solution to a round-bottom flask, place it in an ice bath, use a dropper to slowly add the p-phenylenediamine solution dropwise, turn on the magnetic stirrer at the same time, and continue stirring in the ice bath for 15 minutes to ensure that the solution is evenly mixed and the reaction begins. Then transfer the reaction system to a 25°C environment and continue the reaction for 24 hours. After the reaction is completed, collect the yellow powder product by filtering.

[0044] The collected yellow powder was washed with ethanol and ultrapure water in turn. The powder was transferred to a centrifuge tube, an appropriate amount of washing liquid was added, and the mixture was centrifuged at 6000 rpm for 8 minutes. The supernatant was discarded, and this operation was repeated 6 times to ensure that impurities were removed. Finally, the washed powder was transferred to a vacuum drying oven and dried overnight at 80°C to remove residual ethanol and water to obtain a pure COF-COOH product, which was sealed and stored for later use.

[0045] Weigh 30 mg of silver nitrate solid and 8 mg of COF-COOH powder, add them into a conical flask, gently shake the conical flask to mix the solid powder evenly, and then incubate at room temperature for 20 minutes to allow silver nitrate and COF-COOH to fully contact and interact.

[0046] Take 3mL of 1% sodium citrate solution and place it in a heating device and heat it to 100°C. Use a dropper to add the preheated sodium citrate solution dropwise to the reaction product in the conical flask, while keeping the conical flask at 100°C (a water bath or oil bath device can be used). During the addition process, the color of the solution will gradually change to yellow-green, indicating that the Ag-COF-COOH substrate begins to form. After the addition is completed, continue to stir the reaction at 100°C for 10 minutes to ensure that the reaction is complete. After the reaction is completed, the obtained Ag-COF-COOH substrate is cooled to room temperature.

[0047] Example 2: Building a detection device

[0048] like Figure 2As shown, the detection device used in this method is mainly composed of a reaction pool 1, a peristaltic pump 3, a circulation pool 2, a flow path 5 and a Raman spectrometer 4. Among them, the outlet of the reaction pool 1 is connected to the peristaltic pump 3 through a pipeline, and the peristaltic pump 3 accurately controls the flow rate and flow direction of the solution after the reaction. The outlet pipeline of the peristaltic pump 3 is connected to the inlet of the circulation pool 2. The circulation pool 2 has a detection area inside which the solution can flow evenly, reducing the signal fluctuation caused by the uneven flow of the solution, and fixing the detection probe of the Raman spectrometer 4 in the detection area of ​​the circulation pool 2. The flow path 5 is used to circulate the hydrogen peroxide, and the flow path 5 has a main path 51 and a bypass 52, and the bypass 52 is connected to the reaction pool 1. Thereby, the hydrogen peroxide in the main path 51 of the flow path 5 can flow normally, and the hydrogen peroxide in the bypass 52 can react with the 4-MBA solution in the reaction pool 1 and the Ag-COF-COOH substrate, and the solution after the reaction can enter the circulation pool 2 under the action of the peristaltic pump 3 and be detected by the Raman spectrometer 4.

[0049] Example 3: Detection of hydrogen peroxide concentration

[0050] 5 mg of Ag-COF-COOH substrate was added to 200 mL of water, and then a 4-MBA solution with a concentration of 0.5 mM and a volume of 2 mL was added. The reagent was transported to the circulation pool 2 at a flow rate of 0.1-0.5 mL / min through the peristaltic pump 3, together with the solution in the reaction pool 1. When the solution was flowing stably in the circulation pool 2, the Raman spectrometer 4 was started. According to the set parameters, the excitation wavelength was 785 nm, the laser power was 450 mW, and the spectrum acquisition range was 500-3200 cm -1 , spectral resolution 2cm -1 , the collection time is 3s, and the real-time Raman spectrum of the solution in the flow cell 2 is collected. Figure 3 Table of hydrogen peroxide concentration gradient detection spectra.

[0051] The collected Raman spectral data were subjected to baseline removal and SG filtering to remove noise. A series of standard hydrogen peroxide solutions (0.01mM-1mM) with known concentrations were tested, and then 4-MBA was selected at 1592cm -1 The characteristic peak data corresponding to the C=N and C=CC=C stretching vibration peaks are obtained by the least squares method. The fitting equation is I=261.19C+9391.42, R2=0.99, and the following is obtained: Figure 4 The hydrogen peroxide concentration gradient calibration curve table in Figure 4 It can be seen that the hydrogen peroxide concentration shows good linearity in the range of 2mM-100mM.

[0052] From the above experimental results, we can see that the following effects are achieved by using the above method:

[0053] 1. Surface enhanced Raman spectroscopy technology overcomes the problems of weak hydrogen peroxide Raman signal and complex traditional detection methods. It can monitor the changes in hydrogen peroxide concentration in real time and accurately, and improve the detection efficiency. Its high sensitivity and high selectivity are especially suitable for application scenarios with high requirements for hydrogen peroxide concentration.

[0054] 2. The detection sensitivity is high and can sensitively reflect the changes in hydrogen peroxide concentration.

[0055] 3. Simplifies the Raman analysis process and reduces the reliance on contrast signals and calibration steps.

[0056] The present invention uses specific embodiments to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A method for online detection of hydrogen peroxide concentration based on surface enhanced Raman spectroscopy, characterized in that: The following steps are involved: Preparation of Ag-COF-COOH substrate; Mixing the 4-MBA solution with the Ag-COF-COOH substrate to obtain a mixed detection solution; Passing hydrogen peroxide into the mixed detection solution to obtain a reaction mixture; A Raman spectrometer is used to collect real-time Raman spectra of the reaction mixture to obtain Raman characteristic peaks.

2. The method for online detection of hydrogen peroxide concentration based on surface enhanced Raman spectroscopy according to claim 1, characterized in that: In the step "preparing Ag-COF-COOH substrate", the following steps are included: COF-COOH powder was prepared; Adding silver nitrate solid and the COF-COOH powder into a conical flask for incubation to obtain a reaction product; A sodium citrate solution was added dropwise to the reaction product under high temperature to obtain the yellow-green Ag-COF-COOH substrate.

3. The method for online detection of hydrogen peroxide concentration based on surface enhanced Raman spectroscopy according to claim 2, characterized in that: In the step of "preparing COF-COOH powder", the following steps are included: Adding triformyl chloride to the ethyl acetate solution to obtain triformyl chloride-ethyl acetate solution; Add the triacyl chloride-ethyl acetate solution into a round-bottom flask; Dissolve p-phenylenediamine in ethyl acetate solution, add dropwise into a round-bottom flask with a dropper, and stir in an ice bath to obtain a reaction system; The reaction system is reacted at room temperature to obtain and filter and collect a yellow powder; Washing the yellow powder with ethanol and ultrapure water; The mixture was dried in a vacuum drying oven at 80° C. to 100° C. overnight and excess ethanol and water were evaporated to obtain the COF-COOH powder.

4. The method for online detection of hydrogen peroxide concentration based on surface enhanced Raman spectroscopy according to claim 3, characterized in that: In the step of "washing the yellow powder with ethanol and ultrapure water solution", the ethanol and ultrapure water solution are centrifuged at a speed of 6000-12000 rpm for 8-10 minutes and centrifuged 3-6 times for washing.

5. The method for online detection of hydrogen peroxide concentration based on surface enhanced Raman spectroscopy according to claim 3, characterized in that: In the step of "adding triformyl chloride to the ethyl acetate solution to obtain triformyl chloride-ethyl acetate solution", the triformyl chloride is slowly added to the ethyl acetate solution and stirred until completely dissolved to obtain the triformyl chloride-ethyl acetate solution.

6. The method for online detection of hydrogen peroxide concentration based on surface enhanced Raman spectroscopy according to claim 3, characterized in that: The step of "using a Raman spectrometer to collect real-time Raman spectra of the reaction mixture to obtain Raman characteristic peaks" includes the following steps: The collected Raman spectrum data is subjected to baseline removal and SG filtering to remove noise; A hydrogen peroxide solution of known concentration was tested at different concentrations; Then, the characteristic peak data of 4-MBA at a specific Raman wave number were selected, and the fitting equation of hydrogen peroxide concentration was obtained by the least squares method.

7. The method for online detection of hydrogen peroxide concentration based on surface enhanced Raman spectroscopy according to claim 1, characterized in that: In the step of "using a Raman spectrometer to collect real-time Raman spectra of the reaction mixture to obtain Raman characteristic peaks", the laser wavelength of the Raman spectrometer is 785nm-795nm, the laser power is 100mW-500mW, and the spectrum collection range is 500cm -1 ~3200cm -1 , the spectral resolution is adjusted to 2cm -1 ~8cm -1 , the acquisition time is set to 3s-5s.

8. The method for online detection of hydrogen peroxide concentration based on surface enhanced Raman spectroscopy according to claim 1, characterized in that: include: A reaction cell, wherein the 4-MBA solution and the Ag-COF-COOH substrate are located in the reaction cell; A circulation pool is connected to the reaction pool via a peristaltic pump, the circulation pool has a detection area inside which the solution can flow evenly, and the detection probe of the Raman spectrometer is fixed in the detection area of ​​the circulation pool.

9. The method for online detection of hydrogen peroxide concentration based on surface enhanced Raman spectroscopy according to claim 8, characterized in that: The device also includes a flow passage, wherein the flow passage is used for circulating the hydrogen peroxide, the flow passage has a main passage and a bypass passage, and the bypass passage is in communication with the reaction tank.

10. The method for online detection of hydrogen peroxide concentration based on surface enhanced Raman spectroscopy according to claim 9, characterized in that: After the hydrogen peroxide in the reaction pool reacts with the 4-MBA, the peristaltic pump allows the reaction mixture to enter the circulation pool at a flow rate of 0.1 mL / min-0.5 mL / min.

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