H2S detection method based on combination of MOF microporous adsorption effect and SERS

Abstract

The invention relates to the technical field of gas detection, in particular to an H2S detection method based on MOF microporous adsorption effect and SERS (Surface Enhanced Raman Scattering), which comprises the following steps: S1, synthesizing gamma-CD-MOF-Pluronic; s2, selecting N, N-diethyl-p-phenylenediamine as a probe, and mixing the N, N-diethyl-p-phenylenediamine with NaHS solutions with different concentrations according to a certain proportion; s3, by taking gamma-CD-MOF-Pluronics as a carrier, packaging N, N-diethyl p-phenylenediamine and AuBps (AuBps) together, so as to form a composite detection material; s4, spotting the material on a tinfoil or a silicon wafer, scanning a detection sample by using a Raman spectrometer, carrying out accurate quantitative detection on H2S through an AuBps enhanced Raman signal, analyzing the Raman spectrum signal, and determining the concentration of H2S; the H2S gas is efficiently captured and enriched by utilizing the high specific surface area and the micropore adsorption characteristic of the MOF material, the intensity and the detection sensitivity of Raman signals are remarkably improved by combining the AuBps enhanced SERS technology, and the detection method is simple, is suitable for on-site rapid detection and does not need complex equipment.

Description

Technical Field

[0001] The present invention relates to the technical field of gas detection, and particularly to a method for detecting H2S based on the combination of MOF microporous adsorption effect and SERS. Background Art

[0002] H2S is a colorless and pungent gas, which widely exists in industrial waste gas, sewage treatment and other environments. It is highly toxic, and low concentrations can cause headaches, nausea and other symptoms, while high concentrations may lead to respiratory failure and even be fatal. Therefore, monitoring the concentration of H2S is crucial for ensuring human health and environmental safety.

[0003] Currently, the H2S detection technologies on the market mainly include chemical sensors, electrochemical sensors and optical sensors, etc. However, these technologies generally have certain limitations. Chemical sensors are poor in sensitivity and selectivity and are easily interfered by other gases; although electrochemical sensors are sensitive, their stability is poor in high humidity and high temperature environments; optical sensors are expensive and large in size, making them inconvenient for portable use.

[0004] Therefore, aiming at the problems of being easily interfered by other gases, poor stability in high humidity and high temperature environments, high cost and inconvenient portability, a method for detecting H2S based on the combination of MOF microporous adsorption effect and SERS can be designed. Summary of the Invention

[0005] In order to overcome the problems of being easily interfered by other gases, poor stability in high humidity and high temperature environments, high cost and inconvenient portability.

[0006] The technical solution of the present invention is: a method for detecting H2S based on the combination of MOF microporous adsorption effect and SERS, including the following steps:

[0007] S1: Synthesize γ-CD-MOF using γ-cyclodextrin and potassium hydroxide, form uniform nanoscale MOF crystals after multiple washings, and then add polyoxyethylene-polyoxypropylene-polyoxyethylene block copolymer to synthesize γ-CD-MOF-Pluronics;

[0008] S2: Select N,N-diethyl-p-phenylenediamine as a probe and mix it with NaHS solutions of different concentrations in a certain ratio;

[0009] S3: Using γ-CD-MOF-Pluronics as a carrier, encapsulate N,N-diethyl-p-phenylenediamine and AuBps together to form a composite detection material, place it in the environment of the gas to be detected, adsorb H2S gas, observe the color change of the methylene blue-like complex formed by the reaction of N,N-diethyl-p-phenylenediamine and H2S, and preliminarily judge the H2S concentration;

[0010] S4: Spot the material on tin foil or a silicon wafer, scan and detect the sample using a Raman spectrometer, perform precise quantitative detection of H2S through the Raman signal enhanced by AuBps, analyze the Raman spectral signal, and determine the H2S concentration.

[0011] Preferably, the specific steps for synthesizing γ-CD-MOF-Pluronics are as follows: Mix γ-CD and KOH in pure water, and pre-add MeOH to make a mother liquor. Then seal the mixture and place it in a glass container. Sonicate the mixed solution for 5 minutes to obtain a clear solution. Then, quickly add methanol and polyethylene glycol to the reaction solution, heat the solution at 50 °C for 10 minutes. After 60 minutes, separate and collect the nanoscale MOF crystals, wash them twice with ethanol, dry them overnight under vacuum at 50 °C. Immerse the γ-CD-MOFs in a 5% (v / v) Pluronic ethyl acetate solution at room temperature for 33 hours, wash the material with fresh ethyl acetate, then filter three times, and finally dry it overnight in a vacuum oven at 50 °C.

[0012] Preferably, the dosage ratio of γ-cyclodextrin, potassium hydroxide, pure water, MeOH, methanol, and polyethylene glycol is 162 mg: 56 mg: 5 mL: 3 mL: 8 mL: 68 mg.

[0013] Preferably, the ratio of the probe N,N-diethyl-p-phenylenediamine to NaHS is 1:3.

[0014] Advantages of the present invention: It provides a technical means with high sensitivity, high selectivity, and excellent reproducibility. By utilizing the high specific surface area and microporous adsorption characteristics of MOF materials, efficient capture and enrichment of H2S gas are achieved. At the same time, combined with the SERS technology enhanced by gold nanobipyramids (AuBps), the intensity of the Raman signal and the detection sensitivity are significantly improved. The detection method is simple, suitable for on-site rapid detection, without complex equipment, and has the advantages of high sensitivity, strong specificity, and low cost, effectively meeting the safety monitoring requirements. Description of the Drawings

[0015] Figure 1 Shown are the microscopic morphology, structure, and absorbance of gold nanobipyramids in the H2S detection method of the present invention based on the combination of MOF microporous adsorption effect and SERS, where (A) is the electron micrograph and (B) are the dual characteristic absorption peaks under a UV-visible spectrophotometer;

[0016] Figure 2The Raman spectra in the H2S detection method based on the combination of MOF microporous adsorption effect and SERS of the present invention are shown, where (A) is the control group containing only AuBPs and H2S donors, (B) is the co - action system of AuBPs, H2S donors and molecular probes, (C) is the color reaction after the combination of probe H2S, and (D) is after the outer layer is coated with MOF;

[0017] Figure 3 The detection results of different concentrations in the H2S detection method based on the combination of MOF microporous adsorption effect and SERS of the present invention are shown, where (A) is the blank control group without H2S, (B) is the detection result when the H2S concentration is 10 -3 M, (C) is the detection result when the H2S concentration is 10 -4 M, (D) is the detection result when the H2S concentration is 10 -5 M, (E) is the detection result when the H2S concentration is 10 -6 M, (F) is the detection result when the H2S concentration is 10 -7 M;

[0018] Figure 4 The detection results in different environments in the H2S detection method based on the combination of MOF microporous adsorption effect and SERS of the present invention are shown, where (A) is the reaction situation at - 4°C when the H2S concentration is 10 -3 M, (B) is the reaction situation at room temperature when the H2S concentration is 10 -3 M, (C) is the reaction situation at - 4°C when the H2S concentration is 10 -4 M, (D) is the reaction situation at room temperature when the H2S concentration is 10 -4 M. Detailed implementation manners

[0019] The present invention will be further described below with reference to the drawings and embodiments.

[0020] The present invention provides an embodiment, a H2S detection method based on the combination of MOF microporous adsorption effect and SERS; the method includes the following steps:

[0021] S1: Use γ - cyclodextrin and potassium hydroxide to synthesize γ - CD - MOF, form uniform nanoscale MOF crystals after multiple washings, and then add polyoxyethylene - polyoxypropylene - polyoxyethylene block copolymer to synthesize γ - CD - MOF - Pluronics;

[0022] S2: Select N,N - diethyl - p - phenylenediamine as the probe and mix it with NaHS solutions of different concentrations in a certain proportion;

[0023] S3: Using γ-CD-MOF-Pluronics as a carrier, encapsulate N,N-diethyl-p-phenylenediamine and AuBps together to form a composite detection material. Place it in the environment of the gas to be measured, adsorb H2S gas, and observe the color change of the methylene blue-like complex formed by the reaction of N,N-diethyl-p-phenylenediamine and H2S to preliminarily judge the concentration of H2S.

[0024] S4: Spot the material on tin foil or a silicon wafer, scan and detect the sample using a Raman spectrometer, and accurately quantify H2S through the Raman signal enhanced by AuBps. Analyze the Raman spectrum signal to determine the concentration of H2S.

[0025] Preferably, the specific steps for synthesizing γ-CD-MOF-Pluronics are as follows: Mix γ-CD and KOH in pure water, and pre-add MeOH to make a mother liquor. Then seal the mixture and place it in a glass container. Ultrasonically treat the mixed solution for 5 minutes to obtain a clear solution. Then, quickly add methanol and polyethylene glycol to the reaction solution, heat the solution at 50 °C for 10 minutes. After 60 minutes, separate and collect the nanoscale MOF crystals, wash them twice with ethanol, vacuum dry them overnight at 50 °C. Immerse the γ-CD-MOFs in a 5% (v / v) Pluronic ethyl acetate solution at room temperature for 33 hours, wash the material with fresh ethyl acetate, and then filter three times. Finally, dry it overnight in a vacuum oven at 50 °C.

[0026] Preferably, the dosage ratio of γ-cyclodextrin, potassium hydroxide, pure water, MeOH, methanol, and polyethylene glycol is 162 mg: 56 mg: 5 mL: 3 mL: 8 mL: 68 mg.

[0027] Preferably, the ratio of the probe N,N-diethyl-p-phenylenediamine to NaHS is 1:3, and the concentration range of NaHS is 10 -7 M to 10 -4 M.

[0028] Example 1

[0029] (1) Mix 648 mg of γ-CD and 224 mg of KOH in 20 mL of pure water, and pre-add 12 mL of MeOH to make a mother liquor. Then seal the mixture and place it in a glass container. Ultrasonically treat the mixed solution for 5 minutes to obtain a clear solution. Then, quickly add 32 mL of methanol and 256 mg of polyethylene glycol to the reaction solution. Heat the solution at 50 °C for 10 minutes. After 60 minutes, separate and collect the nanoscale MOF crystals, wash them twice with ethanol, and vacuum dry them overnight at 50 °C. Immerse the γ-CD-MOFs in a 5% (v / v) Pluronic ethyl acetate solution at room temperature for 33 hours, wash the material with fresh ethyl acetate, then filter it three times, and finally dry it overnight in a vacuum oven at 50 °C;

[0030] (2) Mix N,N-diethyl-p-phenylenediamine with NaHS solutions of different concentrations in a certain ratio. After a certain time, it can be observed that the mixed solution above a certain concentration changes color. After the probe is covalently bonded to H2S, a methylene blue-like complex is formed. When the concentration of H2S is relatively high, an obvious color reaction will occur due to the formation of the complex, changing from bright yellow to pink-purple or blue-purple;

[0031] (3) Add a certain amount of AuBps to the mixed solution that did not change color in the above step, mix well, spot-sample, and perform detection using SERS;

[0032] (4) Record the detection results, process the data and images, and draw relevant conclusions;

[0033] It is experimentally known that when the probe N,N-diethyl-p-phenylenediamine and NaHS are in a ratio of 1:3, the color development rate is the fastest and the reaction time is significantly shortened; a visible color change can still occur under 10 -4 M NaHS, with relatively high sensitivity; the SERS combined with AuBps can achieve precise quantitative detection of H2S at a concentration as low as 10 -7 M.

[0034] Example 2

[0035] According to the conclusion of Example 1, with the mass ratio of the probe N,N-diethyl-p-phenylenediamine to NaHS being 1:3 and the concentration of NaHS being 10 -7 M to 10 -4 M, conduct the detection:

[0036] (1) Encapsulate the composite detection material of the probe N,N-diethyl-p-phenylenediamine and AuBps with γ-CD-MOF, place it in the gas environment to be measured, and adsorb H2S gas;

[0037] (2) Observe the color change of the methylene blue-like complex formed by the reaction of N,N-diethyl-p-phenylenediamine and H2S, and preliminarily judge the concentration of H2S;

[0038] (3) Spot the material on tin foil or a silicon wafer, and use a Raman spectrometer to scan and detect the sample. The Raman signal enhanced by AuBps can be used for accurate quantitative detection of H2S;

[0039] (4) Analyze the Raman spectrum signal to determine the concentration of H2S.

[0040] Experimental example

[0041] (1) Use electron microscopy to detect the microscopic morphology and structure of gold nanobipyramids, as Figure 1 shown in (A);

[0042] (2) Detect the double characteristic absorption peaks of AuBPs under an ultraviolet-visible spectrophotometer. The results are as Figure 1 shown in (B). The double characteristic absorption peaks under the ultraviolet-visible spectrophotometer confirm the successful preparation of AuBPs;

[0043] (3) Raman spectrum, a control group containing only AuBPs and an H2S donor Figure 2 (A), a co-action system of AuBPs, an H2S donor, and a molecular probe, as Figure 2 (B), the color reaction after the probe binds to H2S, as Figure 2 (C), after coating with MOF on the outer layer, as Figure 2 (D);

[0044] (4) Detection of different concentrations: Use a blank control group without H2S and H2S concentrations of 10 -3 M, 10 -4 M, 10 -5 M, 10 -6 M, 10 -7 M for detection respectively. The results are as Figure 3 shown, indicating that at all concentrations, the characteristic absorption peaks are clearly visible, indicating that the constructed AuBPs-probe-MOF system has a detection sensitivity of up to 10 -7 M;

[0045] (5) Detection under different concentrations and temperature environments. When the H2S concentrations are 10 -3 M and 10 -4 M respectively, the reactions in an environment of -4 °C and normal temperature are carried out. The results show that the reaction is more efficient at normal temperature.

[0046] Through the above steps, a technical means with high sensitivity, high selectivity and excellent reproducibility is provided. By utilizing the high specific surface area and microporous adsorption characteristics of MOF materials, efficient capture and enrichment of H2S gas are achieved. At the same time, combined with the SERS technology enhanced by gold nanobipyramids (AuBps), the intensity of Raman signals and detection sensitivity are significantly improved. The detection method is simple, suitable for on-site rapid detection, without the need for complex equipment, and has the advantages of high sensitivity, strong specificity and low cost, effectively meeting the safety monitoring requirements to solve the problems of being easily interfered by other gases, poor stability in high humidity and high temperature environments, high cost and inconvenient to carry.

[0047] The above has described the embodiments of the present invention in detail, but the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the gist of the present invention.

Claims

1. A method for detecting H2S based on the combination of the microporous adsorption effect of MOF and SERS; characterized in that: It includes the following steps: S1: Synthesize γ-CD-MOF using γ-cyclodextrin and potassium hydroxide, form uniform nanoscale MOF crystals through multiple washings, and then add polyoxyethylene-polyoxypropylene-polyoxyethylene block copolymer to synthesize γ-CD-MOF-Pluronics; S2: Select N,N-diethyl-p-phenylenediamine as the probe and mix it with NaHS solutions of different concentrations in a certain ratio; S3: Use γ-CD-MOF-Pluronics as the carrier to encapsulate N,N-diethyl-p-phenylenediamine and AuBps together to form a composite detection material. Place it in the gas environment to be measured, adsorb H2S gas, and observe the color change of the methylene blue-like complex formed by the reaction of N,N-diethyl-p-phenylenediamine and H2S to preliminarily judge the H2S concentration; S4: Spot the material on tin foil or a silicon wafer, scan and detect the sample using a Raman spectrometer, and accurately quantitatively detect H2S through the Raman signal enhanced by AuBps. Analyze the Raman spectrum signal to determine the H2S concentration.

2. The H2S detection method based on the combination of MOF microporous adsorption effect and SERS according to claim 1, characterized in that: The specific steps for synthesizing γ-CD-MOF-Pluronics are as follows: Mix γ-CD and KOH in pure water, and pre-add MeOH to make a mother liquor. Then seal the mixture and place it in a glass container. Ultrasonically treat the mixed solution for 5 minutes to obtain a clear solution. Then, quickly add methanol and polyethylene glycol to the reaction solution, heat the solution at 50 °C for 10 minutes. After 60 minutes, separate and collect the nanoscale MOF crystals, wash them twice with ethanol, and vacuum dry them overnight at 50 °C. Immerse the γ-CD-MOFs in a 5% (v / v) Pluronic ethyl acetate solution at room temperature for 33 hours, wash the material with fresh ethyl acetate, and then filter three times. Finally, dry it overnight in a vacuum oven at 50 °C.

3. The H2S detection method based on the combination of MOF microporous adsorption effect and SERS according to claim 2, wherein: The dosage ratio of γ-cyclodextrin, potassium hydroxide, pure water, MeOH, methanol, and polyethylene glycol is 162 mg: 56 mg: 5 mL: 3 mL: 8 mL: 68 mg.

4. The H2S detection method based on the combination of MOF microporous adsorption effect and SERS according to claim 1, characterized in that: The ratio of the probe N,N-diethyl-p-phenylenediamine to NaHS is 1:3.

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