Ag-TiO2-Ag surface enhanced Raman scattering substrate, preparation thereof and application of Ag-TiO2-Ag surface enhanced Raman scattering substrate in antibiotic residue detection or degradation

Abstract

The invention discloses an Ag-TiO2-Ag surface enhanced Raman scattering substrate, preparation thereof and application of the Ag-TiO2-Ag surface enhanced Raman scattering substrate in antibiotic residue detection or degradation, and belongs to the technical field of material preparation and analysis detection. The preparation method of the substrate comprises the following steps: (1) preparing a tetrabutyl titanate-ethanol mixed solution and a silver nitrate-ethanol-nitric acid mixed solution, regulating the molar ratio of Ag to Ti, and then carrying out hydrolysis reaction; (2) carrying out hydrothermal reaction and vacuum drying on the hydrolysis product to obtain a precursor; and (3) carrying out roasting treatment on the precursor, so as to obtain the Ag-TiO2-Ag SERS substrate. The prepared substrate can realize high-sensitivity detection of quinolone antibiotics in a water body, the detection limit reaches 10 <-11 > mol / L level, meanwhile, the substrate has photocatalytic degradation capacity, and the degradation rate within 60 minutes exceeds 90%. The method adopts a conventional process, does not need special equipment, and is suitable for industrial large-scale production and environmental pollutant detection and treatment.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of material preparation and analysis and detection, and particularly relates to an Ag-TiO2-Ag surface-enhanced Raman scattering substrate and a preparation method and application thereof in antibiotic residue detection or degradation. BACKGROUND

[0002] In recent years, environmental residue problems caused by antibiotic abuse are serious, and traditional detection methods (such as high-performance liquid chromatography and electrochemical detection) have problems such as high cost, complicated steps or insufficient sensitivity. Surface-enhanced Raman scattering (SERS) technology is concerned due to high sensitivity and fingerprint identification characteristics, but noble metal substrates (such as Ag and Au) have problems such as high cost and poor stability, and the practical application sensitivity of semiconductor substrates (such as TiO2) needs to be improved. Therefore, development of a composite SERS substrate with high sensitivity, stability and low cost has become a research hotspot. SUMMARY

[0003] In view of the problems of high cost and poor stability of noble metal substrates and insufficient sensitivity of semiconductor substrates in the antibiotic residue detection method in the prior art, the purpose of the application is to provide an Ag-TiO2-Ag surface-enhanced Raman scattering substrate and a preparation method and application thereof in antibiotic residue detection or degradation. The composite of Ag and TiO2 is realized by a doping co-deposition method, the prepared substrate has high sensitivity detection and photocatalytic degradation capacity, and is applied to antibiotic residue detection and degradation in water, the detection limit reaches 1x10 -11 mol / L level, the photocatalytic degradation rate is more than 90%, and the process is simple, the cost is low, and the application is suitable for industrial application.

[0004] To achieve the above purpose, the technical scheme adopted by the application is as follows:

[0005] A preparation method of an Ag-TiO2-Ag surface-enhanced Raman scattering substrate, the method comprises the following steps:

[0006] (1) preparing solution A: mixing 30mL of tetrabutyl titanate with 30mL of anhydrous ethanol; preparing solution B: mixing 120mL of anhydrous ethanol, 30mL of a silver nitrate solution and 6mL of concentrated nitric acid under light shielding conditions, and adjusting the molar ratio of Ag to Ti to be 6%-8%;

[0007] (2) slowly dropping solution B into solution A for hydrolysis after stirring solution B for 10min, and continuously stirring for 2h to obtain Ag-TiO sol;

[0008] (3) taking 40mL of the sol into a reaction kettle for hydrothermal reaction, heating at 160℃ for 6h, removing the supernatant after cooling, and vacuum drying at 80℃ to obtain a precursor;

[0009] (4) After grinding the precursor in the dark, it was calcined in a muffle furnace at 450°C for 4 hours to obtain the Ag-TiO-Ag SERS substrate.

[0010] Further, in step (1), the concentration of the silver nitrate solution is such that the molar ratio of Ag to Ti is 6%, 7%, and 8%, respectively, to obtain 6% Ag-TiO2-Ag, 7% Ag-TiO2-Ag, and 8% Ag-TiO2-Ag substrates.

[0011] Furthermore, in step (3), the hydrothermal reaction is carried out in a reactor, and the drying method is vacuum drying.

[0012] Furthermore, the Ag-TiO2-Ag surface-enhanced Raman scattering substrate prepared using the above method can be applied to the SERS detection of quinolone antibiotics in water, including DIF, CIP, ENR, Dan, and ENX.

[0013] The detection limit of the substrate for quinolone antibiotics is as low as 1×10⁻⁶. -11 The recovery rate in actual water samples was 80.8%-96.4% at mol / L, with a relative standard deviation of ≤4.7%.

[0014] Furthermore, the prepared Ag-TiO2-Ag surface-enhanced Raman scattering substrate can be used for photocatalytic degradation of antibiotics. Under irradiation with a 375W high-pressure mercury lamp (λ=365nm), the Ag-TiO2-Ag SERS substrate showed a degradation rate of ≥95.4% for ENX after 40 min, and a degradation rate of ≥90% for DIF, CIP, ENR, and Dan after 60 min.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0016] 1. This invention prepares an Ag-TiO2-Ag composite substrate via a doping co-deposition method. It utilizes the synergistic enhancement of the SERS signal by the localized surface plasmon resonance (LSPR) of Ag and the charge transfer (CT) effect of TiO2, resulting in a detection sensitivity improvement of 6 orders of magnitude compared to a pure TiO2 substrate, with a detection limit of 10. -11 mol / L level.

[0017] 2. This invention is the first to integrate SERS detection and photocatalytic degradation, achieving an antibiotic degradation rate of over 90% within 60 minutes, providing a multifunctional solution for the treatment of environmental pollutants.

[0018] 3. The method of this invention adopts conventional processes, requires no special equipment or reagents, has low preparation cost and high stability, and is suitable for large-scale industrial production and efficient detection and treatment of antibiotic residues in actual water samples. Attached Figure Description

[0019] Figure 1 This is a flowchart illustrating the preparation process of the Ag-TiO2-Ag SERS substrate of this invention.

[0020] Figure 2 XRD and UV diffuse reflectance images of the Ag-TiO2-Ag SERS substrate prepared in Example 1; where: (a) XRD; (b) UV diffuse reflectance.

[0021] Figure 3 The results are as follows: (a) SERS spectra of different DIF concentrations adsorbed on the Ag-TiO2-Ag substrate; (b) SERS spectra of different DIF concentrations adsorbed on the TiO2 substrate; (c) SERS peak intensity at 1384 cm-1 on the Ag-TiO2-Ag substrate versus logarithmic relationship of DIF concentration.

[0022] Figure 4 The following is a test of the photocatalytic degradation ability of antibiotics on the Ag-TiO2-Ag SERS substrate in Example 3: (a) the relationship between C / C0 of DIF on Ag-TiO2-Ag and TiO2 NPs and photocatalytic time; (b) the relationship between ENX, CIP, ENR and Dan and the photocatalytic time of Ag-TiO2 NPs. Detailed Implementation

[0023] The present invention will be described in detail below with reference to the embodiments.

[0024] This invention provides a method for preparing an Ag-TiO2-Ag SERS substrate, such as... Figure 1 As shown, this method involves steps such as solution preparation, hydrolysis reaction, hydrothermal synthesis, and calcination to control the Ag to Ti molar ratio to 6%-8%, thereby preparing a composite substrate with synergistic effects of localized surface plasmon resonance (LSPR) and charge transfer (CT). The prepared substrate can be used for highly sensitive detection of quinolone antibiotics (such as DIF, CIP, ENR, etc.) in water, while simultaneously achieving efficient degradation of antibiotics under photocatalytic conditions.

[0025] Example 1:

[0026] Preparation of 7% Ag-TiO2-Ag substrate:

[0027] (1) Solution A: 30 mL tetrabutyl titanate + 30 mL anhydrous ethanol, stir well.

[0028] (2) Solution B: 120 mL anhydrous ethanol + 30 mL silver nitrate solution (containing Ag so that the Ag / Ti molar ratio is 7%) + 6 mL concentrated nitric acid, stir for 10 min in the dark.

[0029] (3) Slowly add solution B to solution A and stir continuously for 2 hours to obtain a sol.

[0030] (4) The sol was hydrothermally reacted at 160℃ for 6 hours, dried under vacuum at 80℃, and calcined at 450℃ for 4 hours to obtain a 7% Ag-TiO2-Ag substrate.

[0031] XRD and UV diffuse reflectance patterns of the prepared Ag-TiO2-Ag substrate.

[0032] Example 2:

[0033] Applications of antibiotic testing:

[0034] 0.02 g of the 7% Ag-TiO2-Ag substrate prepared in Example 1 was immersed in 10 mL of a 1×10⁻⁶ solution. -3 -1×10 - 12 A mol / L DIF solution was stirred for 5 hours, centrifuged and dried, and then subjected to SERS testing. Figure 3 As shown, the results indicate that 1384cm -1 The characteristic peak intensity is related to the logarithm of the DIF concentration in the range of 1×10⁻⁶. -5 -1×10 -11 The relationship is linear within the mol / L range (Y = 167.56lgC + 1919.61, R...). 2 =0.9919), the limit of detection is 1×10 -11 mol / L.

[0035] Example 3:

[0036] Photocatalytic degradation experiment:

[0037] The 0.01 g of 7% Ag-TiO2-Ag substrate prepared in Example 1 was dispersed in 100 mL of a solution containing 1×10⁻⁶ g of Ag-TiO2-Ag. -5 An aqueous solution of mol / L LENX was stirred in the dark for 10 hours and then irradiated with a 375W high-pressure mercury lamp. After 40 hours, the degradation rate of ENX reached 95.4%, and after 60 hours, the degradation rates of DIF, CIP, ENR, and Dan were 90.6%, 92.8%, 90.1%, and 92.6%, respectively. Figure 4 As shown.

[0038] Comparative Example 1:

[0039] Preparation and detection of pure TiO2 substrate

[0040] (1) Omit the silver nitrate in solution B, and follow the same steps as in Example 1 to obtain a pure TiO2 substrate.

[0041] (2) The detection limit for DIF is 1×10⁻⁶. -5mol / L, significantly higher than Ag-TiO2-Ag substrate (1×10 mol / L). -11 (mol / L), demonstrating the effect of Ag doping and deposition on improving sensitivity.

[0042] Comparative Example 2:

[0043] Preparation and detection of single Ag sol substrates:

[0044] (1) Reduction method: 200 mL of 0.018% silver nitrate solution was heated to boiling, 4 mL of 1% sodium citrate solution was added, and the reaction was carried out at 95-97℃ for 60 h to obtain Ag sol.

[0045] (2) The detection limit for DIF is 1×10⁻⁶. -7 Although it is better than pure TiO2, it is lower than Ag-TiO2-Ag substrate and has poor stability.

[0046] The substrates prepared in the above embodiments and comparative examples were subjected to performance tests, and the results are summarized in Table 1. The Raman shift distribution of the five antibiotics is shown in Table 2.

[0047] Table 1. Recovery of five antibiotic residues from Songhua River water samples using the SERS method (n=5)

[0048]

[0049]

[0050] Table 2. Raman shift distribution of the five antibiotics

[0051]

[0052] Where ν represents tensile vibration and δ represents bending vibration.

[0053] The above embodiments are for illustrative purposes only and are not intended to limit the invention. Those skilled in the art can make improvements within the scope of the invention without departing from its spirit, such as adjusting the Ag doping ratio or optimizing hydrothermal reaction conditions; all of these improvements fall within the scope of protection of the invention. The scope of protection of the invention is defined by the claims.

Claims

1. A method for preparing an Ag-TiO2-Ag surface-enhanced Raman scattering substrate, characterized in that: The method includes the following steps: (1) Preparation of solution A: Mix 30 mL of tetrabutyl titanate with 30 mL of anhydrous ethanol; Preparation of solution B: Under light-protected conditions, mix 120 mL of anhydrous ethanol, 30 mL of silver nitrate solution and 6 mL of concentrated nitric acid, and adjust the molar ratio of Ag to Ti to 6%-8%; (2) After stirring solution B for 10 min, slowly add it dropwise to solution A for hydrolysis, and continue stirring for 2 h to obtain Ag-TiO2 sol; (3) Take 40 mL of sol and put it into the reaction vessel for hydrothermal reaction. Heat at 160 °C for 6 h, cool and remove the supernatant, and dry under vacuum at 80 °C to obtain the precursor; (4) After grinding the precursor in the dark, it was calcined in a muffle furnace at 450 °C for 4 h to obtain the Ag-TiO2-Ag SERS substrate.

2. The method for preparing the Ag-TiO2-Ag surface-enhanced Raman scattering substrate according to claim 1, characterized in that: In step (1), the concentration of the silver nitrate solution is such that the molar ratio of Ag to Ti is 6%, 7% and 8%, respectively, to obtain 6% Ag-TiO2-Ag, 7% Ag-TiO2-Ag and 8% Ag-TiO2-Ag substrates.

3. The method for preparing the Ag-TiO2-Ag surface-enhanced Raman scattering substrate according to claim 1, characterized in that: In step (3), the hydrothermal reaction is carried out in a reactor and the drying method is vacuum drying.

4. An Ag-TiO2-Ag surface-enhanced Raman scattering substrate prepared by any one of the methods described in claims 1-3.

5. The application of the Ag-TiO2-Ag surface-enhanced Raman scattering substrate according to claim 4 in the detection of antibiotic residues, characterized in that: The substrate is used for SERS detection of quinolone antibiotics in water, including DIF, CIP, ENR, Dan, and ENX.

6. The application of the Ag-TiO2-Ag surface-enhanced Raman scattering substrate according to claim 5 in the detection of antibiotic residues, characterized in that: The detection limit of the substrate for quinolone antibiotics is as low as 1×10⁻⁶. -11 The recovery rate in actual water samples was 80.8%-96.4% at mol / L, with a relative standard deviation of ≤4.7%.

7. The application of the Ag-TiO2-Ag surface-enhanced Raman scattering substrate according to claim 4 in antibiotic degradation, characterized in that: The substrate was applied to the photocatalytic degradation of antibiotics. Under irradiation with a 375 W high-pressure mercury lamp (λ=365 nm), the Ag-TiO2-Ag SERS substrate showed a degradation rate of ≥95.4% for ENX after 40 min, and a degradation rate of ≥90% for DIF, CIP, ENR, and Dan after 60 min.

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