Application of Ag / Al-Bi2WO6 composite SERS substrate in detection of 4-MBA in industrial wastewater

Abstract

The application belongs to the technical field of SERS detection, and particularly relates to application of an Ag / Al-Bi2WO6 composite SERS substrate in detection of 4-MBA in industrial wastewater. Al-Bi2WO6 nanoparticles are prepared by a calcination method; Ag nanoparticles are grown on the surface of the Al-Bi2WO6 material by an in-situ reduction method, and Ag / Al-Bi2WO6 is obtained by drying, and the Ag / Al-Bi2WO6 composite SERS substrate is obtained by loading the Ag / Al-Bi2WO6 on a glass sheet. The application constructs an efficient interface charge transfer channel by integrating the local surface plasmon resonance effect of Ag nanoparticles and the charge separation capacity of Al-Bi2WO6, and enhances the Raman signal of 4-MBA molecules. The substrate has electromagnetic enhancement and chemical enhancement synergistic effect, and realizes high-sensitivity and specificity detection of trace 4-MBA.

Description

Technical Field

[0001] This invention belongs to the field of SERS detection technology, specifically relating to the application of an Ag / Al-Bi2WO6 composite SERS substrate in the detection of 4-MBA in industrial wastewater. Background Technology

[0002] Industrial wastewater discharge contains a large number of toxic and harmful pollutants, among which 4-mercaptobenzoic acid (4-MBA), a typical aromatic sulfur-containing pollutant, is widely generated in chemical synthesis, pharmaceutical production, food processing, and other industrial fields. This pollutant is characterized by low concentrations, high toxicity, reluctance to degrade, and easy accumulation in water and soil. Even at trace concentrations, it can cause serious harm to the ecological environment and human health. Therefore, achieving rapid, sensitive, and accurate detection of 4-MBA in industrial wastewater is a key requirement in environmental protection and pollution control. Currently, commonly used methods for detecting 4-MBA in industrial wastewater include high-performance liquid chromatography (HPLC), atomic absorption spectrometry (AAS), and electrochemical detection. While these methods offer high detection accuracy, they generally suffer from drawbacks such as long detection cycles, complex sample pretreatment, expensive equipment, cumbersome operating procedures, and difficulty in achieving rapid on-site detection. These limitations hinder their widespread application in industrial wastewater pollution control, as they cannot meet the practical needs of on-site screening and real-time monitoring of 4-MBA in industrial wastewater.

[0003] Surface-enhanced Raman scattering (SERS) technology, as an ultra-sensitive spectroscopic detection technique, boasts unique advantages such as fast detection speed, no need for complex pretreatment, and the ability to detect trace amounts. It shows broad application prospects in the detection of trace 4-MBA in industrial wastewater. The SERS substrate, as the core of this technology, directly determines the sensitivity, stability, and repeatability of 4-MBA detection. Bi₂WO₆ possesses good chemical stability and environmental friendliness. Al doping can modulate the crystal structure and electronic energy levels of Bi₂WO₆, improving its surface charge transfer efficiency and thus synergistically enhancing the Raman signal of 4-MBA. Ag nanoparticles, due to their significant LSPR effect and relatively low cost, have become the most commonly used noble metal modification material. Currently, there are no reports on the application of Ag / Al-Bi₂WO₆ composite structures as SERS substrates for the detection of 4-MBA in industrial wastewater. There is an urgent need to develop a composite SERS substrate that combines enhanced activity, good stability, and practicality to address the shortcomings of existing detection methods and substrates, and meet the practical needs of rapid and sensitive detection of trace 4-MBA in industrial wastewater. Summary of the Invention

[0004] To address the problems in the prior art, this invention provides an application of an Ag / Al-Bi2WO6 composite SERS substrate in the detection of 4-MBA in industrial wastewater.

[0005] The technical solution of the present invention is as follows: an application of an Ag / Al-Bi2WO6 composite SERS substrate in the detection of 4-MBA in industrial wastewater.

[0006] The above application is performed as follows: the Ag / Al-Bi2WO6 composite SERS substrate is immersed in wastewater containing 4-MBA for 1 hour, then removed and dried in air, and the dried composite SERS substrate is subjected to Raman scattering spectroscopy.

[0007] In the above application, the concentration of the 4-MBA solution is 10. -3 M-10 -7 M.

[0008] The above-mentioned application, the preparation method of the Ag / Al-Bi2WO6 composite SERS substrate includes the following steps:

[0009] 1) Bismuth nitrate, nano-tungsten trioxide and alumina were thoroughly ground and then transferred to a muffle furnace for calcination. After natural cooling, Al-Bi2WO6 nanoparticles were precipitated.

[0010] 2) Disperse the Al-Bi2WO6 nanoparticles obtained in step 1) in a mixed solution of 10% ethanol and polyvinylpyrrolidone, sonicate and stir, and then add ammonia to adjust the pH value to 8-9.

[0011] 3) Disperse silver nitrate in the mixed solution obtained in step 2) and stir thoroughly;

[0012] 4) Disperse ascorbic acid in the mixed solution obtained in step 3), stir thoroughly, and obtain the target product Ag / Al-Bi2WO6 after washing, drying and grinding;

[0013] 5) Load the Ag / Al-Bi2WO6 obtained in step 4) onto a clean glass slide to obtain the Ag / Al-Bi2WO6 composite SERS substrate.

[0014] In the above application, in step 1), the molar ratio of bismuth nitrate, nano-tungsten trioxide, and aluminum oxide is 1.94:1:0.03.

[0015] In the above application, in step 1), the calcination temperature is 600 ℃, the heating rate is 5 ℃ / min, and the time is 5h.

[0016] In the above application, step 2), the ratio of Al-Bi2WO6 nanoparticles to 10% ethanol to polyvinylpyrrolidone is 1000 mg to 50 mL to 50 mg.

[0017] In the above application, in step 2), the ultrasonic time is 60 min, the stirring speed is 400 rpm, and the time is 20 min; in step 3), the stirring speed is 400 rpm and the time is 20 min; in step 4), the stirring speed is 400 rpm and the time is 20 min.

[0018] In the above application, the molar ratio of Al-Bi2WO6 nanoparticles, silver nitrate, and ascorbic acid in step 4) is 6:2:1.

[0019] In the above application, step 4), the washing method is centrifugal washing, the centrifugation rate is 8000 r / min, the centrifugation time is 15 min, the drying temperature is 60 ℃, and the drying time is 8 h.

[0020] The beneficial effects of this invention are as follows:

[0021] 1. This invention prepares an Ag / Al-Bi2WO6 composite SERS substrate, which can be used to sample analytes in industrial wastewater and achieve trace detection of 4-MBA.

[0022] 2. The Ag / Al-Bi2WO6 composite SERS substrate prepared by this invention has good chemical stability and anti-interference ability. The LSPR effect of Ag nanoparticles and the charge transfer effect of Al-doped Bi2WO6 work synergistically to quickly capture the Raman signal of 4-MBA molecules. The single detection time is short, which can realize the batch rapid detection of 4-MBA in industrial wastewater and meet the actual needs of industrial wastewater discharge detection.

[0023] 3. The Ag / Al-Bi2WO6 composite SERS substrate prepared by this invention has a strong SERS enhancement effect, efficient targeted adsorption capacity, excellent structural stability and simple operation performance, providing a reliable technical solution for the efficient detection of 4-MBA in industrial wastewater. Attached Figure Description

[0024] Figure 1 X-ray diffraction patterns of Al-Bi2WO6 prepared in Example 1 and Ag / Al-Bi2WO6 prepared in Example 2.

[0025] Figure 2 The SERS spectra obtained by detecting different concentrations of 4-MBA solutions on the Ag / Al-Bi2WO6 composite SERS substrate prepared in Example 2 are shown.

[0026] Figure 3 In Example 2, A represents the 4-MBA solution obtained by randomly selecting 10 points on the Ag / Al-Bi2WO6 composite SERS substrate after it has been placed at room temperature for one month. -3M) Raman spectrum. Figure 3 B represents 10 test points at the 4-MBA characteristic Raman peak at 1584 cm. -1 A bar chart showing the intensity values ​​at a given location. Detailed Implementation

[0027] Example 1

[0028] The preparation method of Al-Bi2WO6 is as follows:

[0029] 4.05 g of bismuth nitrate pentahydrate, 1 g of nano-tungsten trioxide and 0.013 g of commercially available alumina were thoroughly ground and then transferred to a muffle furnace for calcination at a temperature of 600 ℃, a heating rate of 5 ℃ / min and a duration of 5 h. After natural cooling, Al-Bi2WO6 nanoparticles were precipitated by the molten salt method.

[0030] Example 2

[0031] The preparation method of Ag / Al-Bi2WO6 composite SERS substrate is as follows:

[0032] Take 1 g of Al-Bi2WO6 prepared in Example 1 and disperse it in 50 mL of 10% ethanol solution. Add 5 mg of polyvinylpyrrolidone, sonicate for 60 min and stir magnetically for 20 min. Then add 0.2 mL of ammonia water and adjust the pH value to 8-9. After stirring magnetically until uniform, add 78.7 mg of silver nitrate and stir magnetically for 20 min. Add 49 mg of ascorbic acid and stir magnetically for 120 min. After centrifugation and washing (centrifugation rate of 8000 r / min, centrifugation time of 15 min), dry at 60 ℃ for 8 h, and grind to obtain Ag / Al-Bi2WO6. Take 20 μL of Ag / Al-Bi2WO6 solution (1 mg / mL) and drop it on a clean glass slide of 25×76 mm to obtain Ag / Al-Bi2WO6 composite SERS substrate.

[0033] Figure 1 X-ray diffraction patterns of Al-Bi2WO6 prepared in Example 1 and Ag / Al-Bi2WO6 composite SERS substrates prepared in Example 2. Figure 1 In the study, characteristic diffraction peaks appearing at 2θ = 38.2°, 44.4°, 64.5°, and 77.5° correspond to characteristic peaks of Ag. Characteristic peaks also appear on Al-Bi₂WO₆ nanoparticles at 2θ = 27.6°, 31.9°, 47.1°, and 55.7°. The observation of characteristic peaks for both Al-Bi₂WO₆ nanoparticles and Ag in Ag / Al-Bi₂WO₆ indicates the successful preparation of the Ag / Al-Bi₂WO₆ composite SERS substrate.

[0034] Example 3

[0035] Application of Ag / Al-Bi2WO6 composite SERS substrate in the detection of 4-MBA in industrial wastewater.

[0036] The Ag / Al-Bi2WO6 composite SERS substrate was immersed in a solution containing 4-MBA for 1 h, then removed and dried in air. The dried composite SERS substrate was then subjected to Raman scattering spectroscopy.

[0037] Figure 2 For the detection of 4-MBA solution (10) on the Ag / Al-Bi2WO6 composite SERS substrate -3 M-10 -7 SERS spectrum of M). Figure 2 As shown, the intensity of the characteristic peak SERS increases significantly with increasing 4-MBA solution concentration, even at concentrations as low as 10. -7 M, 1584 cm can still be clearly observed. -1 The characteristic peaks of the SERS spectrum at that location. Figure 3 In Example 2, A represents the 4-MBA solution obtained by randomly selecting 10 points on the Ag / Al-Bi2WO6 composite SERS substrate after it has been placed at room temperature for one month. -3 M) Raman spectrum. It can be seen from the figure that the intensity of its Raman characteristic peaks has not decreased significantly compared with a month ago, and the peak position and peak height of the 10 spectral curves are consistent, indicating that the signal response of the SERS substrate at different sites has good consistency. Figure 3 B represents 10 test points at the 4-MBA characteristic Raman peak at 1584 cm. -1 The intensity histogram at the specified location shows an RSD of 7.84%, indicating that the substrate maintains good signal reproducibility even after being placed at room temperature for one month. In summary, these results demonstrate that the Ag / Al-Bi2WO6 composite SERS substrate possesses good sensitivity, stability, and homogeneity, making it a reliable SERS substrate for detection.

Claims

1. An application of an Ag / Al-Bi2WO6 composite SERS substrate in the detection of 4-MBA in industrial wastewater, characterized in that, The preparation method of the Ag / Al-Bi2WO6 composite SERS substrate includes the following steps: 1) Bismuth nitrate, nano-tungsten trioxide and alumina were thoroughly ground and then transferred to a muffle furnace for calcination. After natural cooling, Al-Bi2WO6 nanoparticles were precipitated. 2) Disperse the Al-Bi2WO6 nanoparticles obtained in step 1) in a mixed solution of 10% ethanol and polyvinylpyrrolidone, sonicate and stir, and then add ammonia to adjust the pH value to 8-9. 3) Disperse silver nitrate in the mixed solution obtained in step 2) and stir thoroughly; 4) Disperse ascorbic acid in the mixed solution obtained in step 3), stir thoroughly, and obtain the target product Ag / Al-Bi2WO6 after washing, drying and grinding; 5) Load the Ag / Al-Bi2WO6 obtained in step 4) onto a clean glass slide to obtain the Ag / Al-Bi2WO6 composite SERS substrate.

2. The application according to claim 1, characterized in that, The method is as follows: The Ag / Al-Bi2WO6 composite SERS substrate was immersed in wastewater containing 4-MBA for 1 h, then removed and dried in air. The dried composite SERS substrate was then subjected to Raman scattering spectroscopy.

3. The application according to claim 2, characterized in that, The concentration of the 4-MBA solution is 10. -3 M-10 -7 M.

4. The application according to claim 1, characterized in that, In step 1), the molar ratio of bismuth nitrate, nano-tungsten trioxide and aluminum oxide is 1.94:1:0.

03.

5. The application according to claim 1, characterized in that, In step 1), the calcination temperature is 600 ℃, the heating rate is 5 ℃ / min, and the time is 5 h.

6. The application according to claim 1, characterized in that, In step 2), the ratio of Al-Bi2WO6 nanoparticles to 10% ethanol to polyvinylpyrrolidone is 1000 mg to 50 mL to 50 mg.

7. The application according to claim 1, characterized in that, In step 2), the ultrasonic time is 60 min, the stirring speed is 400 rpm, and the time is 20 min; in step 3), the stirring speed is 400 rpm and the time is 20 min; in step 4), the stirring speed is 400 rpm and the time is 20 min.

8. The application according to claim 1, characterized in that, In step 4), the molar ratio of Al-Bi2WO6 nanoparticles, silver nitrate, and ascorbic acid is 6:2:

1.

9. The application according to claim 1, characterized in that, In step 4), the washing method is centrifugal washing, with a centrifugation rate of 8000 r / min, a centrifugation time of 15 min, a drying temperature of 60 ℃, and a drying time of 8 h.

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