Covalent organic framework nanometallic composite material, preparation method and application thereof
By preparing covalent organic framework nano-noble metal composite materials, the problems of easy aggregation and poor chemical affinity of nano-noble metals were solved, and efficient enrichment and sensitive detection of antibiotics and microplastics were achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HUBEI INST OF PROD QUALITY SUPERVISION & INSPECTION
- Filing Date
- 2024-05-27
- Publication Date
- 2026-06-23
AI Technical Summary
Nanomaterials of precious metals are prone to agglomeration, which leads to a decrease in surface enhancement effect. They also have poor chemical affinity with complex organic pollutants such as antibiotics and microplastics, making them difficult to effectively enrich and detect.
A method for preparing covalent organic framework nano-noble metal composite materials was adopted. Flower-like COF materials were synthesized from 1,3,5-tris(4-aminophenyl)benzene and 2,5-divinyl terephthalaldehyde monomers. Uniform gold nanoparticles were generated by utilizing the reducing functional groups such as vinyl groups in the structure. Subsequently, they reacted with gold and silver ions to form COF-Au@Ag composite materials, which have abundant functional groups to enhance adsorption performance.
The uniform distribution of nano-precious metals and abundant surface-enhancing hot spots were achieved, which improved the adsorption capacity and detection sensitivity for antibiotics and microplastics, with detection limits as low as 0.002 mg L⁻¹ and 0.029 mg L⁻¹, respectively.
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Figure CN118616018B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of new materials technology, and in particular to a covalent organic framework nanocomposite material, its preparation method and application. Background Technology
[0002] Covalent organic frameworks (COFs) are a class of porous materials with three-dimensional structures, formed by covalently linking organic monomers. They possess characteristics such as large surface area, abundant pore structure, and flexible tunable structure, demonstrating promising applications in energy, catalysis, and adsorption. Notably, as materials with tunable three-dimensional structures, COFs can be synthesized under controlled conditions to create three-dimensional network structures with controllable morphology and large specific surface area. Using them as loading materials for gold and silver nanoparticles can effectively prevent their aggregation, thereby significantly improving the surface enhancement properties of the substrate material. More importantly, as organic materials, COFs, containing abundant functional groups such as benzene rings, hydroxyl groups, and carboxyl groups, exhibit excellent chemical affinity for novel organic pollutants, enabling the selective enrichment of trace amounts of these pollutants.
[0003] Surface-enhanced Raman spectroscopy is a novel trace analysis technique characterized by high sensitivity, strong selectivity, simple pretreatment, and portable equipment, attracting widespread attention in environmental and biological analysis fields. However, the surface enhancement effect typically relies on noble metal nanomaterials such as gold and silver nanoparticles capable of generating surface plasmon enhancement.
[0004] Regarding the aforementioned technologies, the inventors believe that the following technical defects exist and require improvement:
[0005] Due to their large specific surface area and high surface energy, nanomaterials of noble metals are prone to aggregation, leading to a decrease in surface enhancement effects. Therefore, it remains difficult to construct substrate materials with uniform and stable distribution of nanomaterials of gold and silver, while also generating surface enhancement hotspots. At the same time, because organic pollutants of concern in the environmental field, especially new pollutants such as antibiotics and microplastics that are currently more complex to detect, lack chemical affinity with nanomaterials of gold and silver, when directly using nanomaterials of gold and silver to detect these pollutants, it is difficult for the pollutants to be effectively enriched and pulled to the vicinity of the substrate material surface. Furthermore, the surface enhancement effect generated by nanomaterials of noble metals is usually effective within 10 nm, making it difficult to meet the actual analytical needs for detecting these pollutants. Summary of the Invention
[0006] This application provides a covalent organic framework nanocomposite material, its preparation method, and its application, to address the following technical problems:
[0007] Constructing a substrate material with a uniform and stable distribution of nano-gold and silver that can generate surface-enhancing hotspots remains quite difficult. Furthermore, novel pollutants such as antibiotics and microplastics, which are more complex to detect, lack chemical affinity with nano-gold and silver. When nano-gold and silver are used directly for the detection of these pollutants, the pollutants are difficult to be effectively enriched and pulled into the vicinity of the substrate material surface. Moreover, the surface enhancement effect generated by nano-noble metal materials is usually effective within 10 nm, which makes it difficult to meet the actual analytical needs for the detection sensitivity of these pollutants.
[0008] In a first aspect, this application provides a method for preparing a covalent organic framework nanocomposite material, employing the following technical solution:
[0009] A method for preparing a covalent organic framework nanocomposite material includes the following steps:
[0010] Step 1, Monomer Dissolution: At room temperature, 1,3,5-tris(4-aminophenyl)benzene and 2,5-divinylterephthalaldehyde monomers are dissolved separately in organic solvents by sonication. Acetic acid is then slowly added dropwise to the two solutions under sonication conditions to obtain solution A and solution B.
[0011] Step 2, Mixing and centrifugation precipitation: After mixing solution A and solution B evenly, let them stand for 60-80 hours to obtain mixture A. Then, mix solution A is thoroughly stirred, precipitated and centrifuged to obtain precipitate A.
[0012] Step 3, washing and drying: precipitate A is washed multiple times to obtain precipitate C. Finally, precipitate C is dried at 55-65℃ under vacuum to obtain flower-shaped COF material.
[0013] Step 4, gold and silver ion reaction: The flower-shaped COF material is dispersed in ultrapure water under ultrasonic conditions to obtain a COF material dispersion. During stirring, HAuCl4 solution is added dropwise to the COF material dispersion, and stirring is continued for 20-40 minutes to obtain a COF-Au composite material dispersion.
[0014] Step 5, composite material dispersion: Add sodium citrate to the COF-Au composite material dispersion, stir at 60-80℃ for 4-6 minutes, then slowly add silver nitrate solution, and continue the reaction for 50-70 minutes to obtain the COF-Au@Ag composite material dispersion, which is a covalent organic framework nano-noble metal composite material.
[0015] In one feasible technical solution of this application, in step one, the molar ratio of the two monomers 1,3,5-tris(4-aminophenyl)benzene and 2,5-divinyl terephthalaldehyde is 2:3, wherein the amount of 1,3,5-tris(4-aminophenyl)benzene monomer is 0.04 mmol, the amount of 2,5-divinyl terephthalaldehyde monomer is 0.06 mmol, and the amount of acetic acid is 0.6-2 mL.
[0016] In one feasible technical solution of this application, the organic solvent in step one is acetonitrile, and the amount of acetonitrile used is 4-6 mL.
[0017] In one feasible technical solution of this application, in step three, precipitate A is first washed with tetrahydrofuran to obtain precipitate B, and then precipitate B is washed a second time with ethanol to remove unreacted monomers to obtain precipitate C.
[0018] In one feasible technical solution of this application, in step four, the amount of flower-shaped COF material used is between 20-30 mg, the concentration of HAuCl4 solution is between 0.6-2.5%, the total volume of HAuCl4 solution used is between 25-200 μL, and the amount of ultrapure water used is between 8-12 mL.
[0019] In one feasible technical solution of this application, in step five, Ag in the silver nitrate solution... + With AuCl4 - The molar ratio is 40:1-200:1, and the amount of sodium citrate used is between 32-38 mg.
[0020] In one feasible technical solution of this application, in step five, the dropping rate of the silver nitrate solution is 0.4-0.6 mL per minute.
[0021] Secondly, this application provides a covalent organic framework nanocomposite material, which adopts the following technical solution:
[0022] A covalent organic framework nanocomposite material is prepared by the above-described method.
[0023] Thirdly, this application provides a method for trace detection of antibiotics, employing the following technical solution:
[0024] A trace detection method for antibiotics involves mixing an equal volume of the COF-Au@Ag composite material dispersion with an antibiotic solution, vortexing for 50-70 seconds, allowing it to stand for 8-12 minutes, then dropping the mixture onto a glass slide and placing it under the probe of a fiber optic Raman spectrometer for Raman detection. The Raman spectrometer detection conditions are as follows: laser wavelength 785 nm, laser intensity 50 mW, integration time 1 s, integration times 20, with different sampling points randomly selected for each sample, and at least 10 samples collected. The obtained spectra are averaged to obtain the final Raman spectrum of the sample.
[0025] Fourthly, this application provides a method for detecting microplastics, employing the following technical solution:
[0026] A method for detecting microplastics involves mixing an equal volume of the COF-Au@Ag composite material dispersion with a microplastic dispersion, vortexing for 50-70 seconds, allowing it to stand for 8-12 minutes, then dropping the mixture onto a glass slide and placing it under the probe of a fiber optic Raman spectrometer for Raman detection. The Raman spectrometer detection conditions are as follows: laser wavelength 785 nm, laser intensity 50 mW, integration time 1 s, integration times 20, with different sampling points randomly selected for each sample, and at least 10 samples collected. The obtained spectra are averaged to obtain the final Raman spectrum of the sample.
[0027] In summary, this application includes at least one of the following beneficial technical effects:
[0028] The flower-like COF material prepared by the method described in this application has a large specific surface area (approximately 2000 m²). 2 g -1 (Left and right); Using this COF as a template, and utilizing the reducing functional groups such as vinyl groups in its structure, a large amount of uniform gold nanoparticles can be generated on its surface without the use of external reducing agents. Because the reducing functional groups in its structure are evenly distributed, the generated gold nanoparticles have the characteristics of uniform particle size and uniform distribution, which ensures the uniformity of the subsequent generation of silver nanoparticles.
[0029] The prepared COF-Au@Ag composite material contains a large number of densely packed and controllable-size silver nanoparticles, generating numerous localized surface plasmon electromagnetic field "hot spots." This ensures the composite material's excellent surface-enhanced Raman spectroscopy (SERS) enhancement capabilities and good signal reproducibility. Furthermore, the COF-Au@Ag composite material possesses abundant functional groups such as benzene rings, imino groups, and vinyl groups. Since novel pollutants like antibiotics and microplastics contain active sites such as benzene rings, carboxyl groups, and amino groups, strong hydrophobic, electrostatic, π-π, and hydrogen bonding interactions can occur between them, further enhancing the adsorption and enrichment capabilities for these pollutants. Using the COF-Au@Ag composite material as a surface-enhanced Raman spectroscopy (SERS) substrate, it can be used for the efficient enrichment and sensitive detection of trace antibiotics and microplastics in complex plant samples, exhibiting high detection sensitivity with detection limits as low as 0.002 mg / L. -1 and 0.029 mg / L -1 It is expected to find wide application in the field of trace analysis of new pollutants. Attached Figure Description
[0030] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0031] Figure 1 This is a process flow diagram of the preparation method of the covalent organic framework nano-noble metal composite material of Example 1 of this application.
[0032] Figure 2 The images show the transmission electron microscope (TEM) image, N2 adsorption-desorption curve, and X-ray diffraction pattern of the flower-shaped COF obtained in Example 1.
[0033] Figure 3 Transmission electron microscopy (TEM) images of the COF-Au@Ag composite materials obtained in Examples 1, 2, and 6.
[0034] Figure 4 The surface reinforcement properties of the COF-Au@Ag composite materials obtained in Examples 1-6 are characterized.
[0035] Figure 5 The image shows the detection results of the COF-Au@Ag composite material used in Example 1 for antibiotics.
[0036] Figure 6 The image shows the detection results of COF-Au@Ag composite material applied to microplastics in Application Example 2. Detailed Implementation
[0037] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings, embodiments, and application examples. It should be understood that the specific embodiments and application examples described herein are merely illustrative of this application and are not intended to limit the scope of this application.
[0038] The following is in conjunction with the appendix Figure 1-6 This application will be described in further detail.
[0039] Example 1
[0040] Example 1 of this application discloses a method for preparing a covalent organic framework nanocomposite material.
[0041] Reference Figure 1 This includes the following steps:
[0042] Step 1, Monomer Dissolution: At room temperature, 1,3,5-tris(4-aminophenyl)benzene and 2,5-divinylterephthalaldehyde monomers are dissolved separately in organic solvents by sonication. Acetic acid is then slowly added dropwise to the two solutions under sonication conditions to obtain solution A and solution B.
[0043] Step 2, Mixing and centrifugation precipitation: After mixing solution A and solution B evenly, let them stand for 60-80 hours to obtain mixture A. Then, mix solution A is thoroughly stirred, precipitated and centrifuged to obtain precipitate A.
[0044] Step 3, washing and drying: precipitate A is washed multiple times to obtain precipitate C. Finally, precipitate C is dried at 55-65℃ under vacuum to obtain flower-shaped COF material.
[0045] Step 4, gold and silver ion reaction: The flower-shaped COF material is dispersed in ultrapure water under ultrasonic conditions to obtain a COF material dispersion. During stirring, HAuCl4 solution is added dropwise to the COF material dispersion, and stirring is continued for 20-40 minutes to obtain a COF-Au composite material dispersion.
[0046] Step 5, composite material dispersion: Add sodium citrate to the COF-Au composite material dispersion, stir at 60-80℃ for 4-6 minutes, then slowly add silver nitrate solution, and continue the reaction for 50-70 minutes to obtain the COF-Au@Ag composite material dispersion, which is a covalent organic framework nano-noble metal composite material.
[0047] In step one, the molar ratio of the two monomers, 1,3,5-tris(4-aminophenyl)benzene and 2,5-divinyl terephthalaldehyde, is 2:3, wherein the amount of 1,3,5-tris(4-aminophenyl)benzene monomer used is 0.04 mmol, the amount of 2,5-divinyl terephthalaldehyde monomer used is 0.06 mmol, and the amount of acetic acid used is 0.6-2 mL; and the organic solvent is acetonitrile, and the amount of acetonitrile used is 5 mL (in other embodiments, the amount of acetonitrile used can also be 4 mL or 6 mL).
[0048] In step three, precipitate A is first washed with tetrahydrofuran to obtain precipitate B, and then precipitate B is washed a second time with ethanol to remove unreacted monomers to obtain precipitate C.
[0049] In step four, the amount of flower-shaped COF material used is between 20-30 mg, and the concentration of HAuCl4 solution is 1% (in other embodiments, the concentration may also be 0.6%, 1.2%, 1.8%, or 2.5%), and the total volume of HAuCl4 solution used is 100 μL (in other embodiments, the total volume may also be 25 μL, 50 μL, 75 μL, 125 μL, 150 μL, 175 μL, or 200 μL), and the amount of ultrapure water used is 10 mL (in other embodiments, the volume may also be 8 mL, 9 mL, 11 mL, or 12 mL).
[0050] In step five, Ag in the silver nitrate solution + With AuCl4 - The molar ratio is 100:1, and the amount of sodium citrate used is 35 mg (in other embodiments, this amount may also be 32 mg, 33 mg, 34 mg, 36 mg, 37 mg or 38 mg).
[0051] In step five, the silver nitrate solution is added at a rate of 0.4-0.6 mL per minute (preferably 0.5 mL per minute to ensure a complete reaction).
[0052] The transmission electron microscope (TEM) image (first from left), N2 adsorption-desorption curve (second from left), and X-ray diffraction pattern (first from right) of the COF-Au@Ag composite material obtained in Example 1 are shown below. Figure 2 As shown, the obtained COF-Au@Ag composite material has a flower-like morphology and numerous protrusions on its surface. Therefore, the COF-Au@Ag composite material has a large specific surface area of approximately 2000 m². 2 g -1 This is beneficial for constructing three-dimensional composite nanomaterials. Moreover, the X-ray diffraction pattern of the COF-Au@Ag composite material matches well with the simulated standard pattern, indicating the successful synthesis of the COF-Au@Ag composite material without other impurities.
[0053] The beneficial technical effects of the covalent organic framework nano-noble metal composite material of this application embodiment are roughly as follows:
[0054] The flower-like COF material prepared by the method described in this application has a large specific surface area (approximately 2000 m²). 2 g -1 (Left and right); Using this COF as a template, and utilizing the reducing functional groups such as vinyl groups in its structure, a large amount of uniform gold nanoparticles can be generated on its surface without the use of external reducing agents. Because the reducing functional groups in its structure are evenly distributed, the generated gold nanoparticles have the characteristics of uniform particle size and uniform distribution, which ensures the uniformity of the subsequent generation of silver nanoparticles.
[0055] The prepared COF-Au@Ag composite material contains a large number of densely packed and controllable-size silver nanoparticles, generating numerous localized surface plasmon electromagnetic field "hot spots." This ensures the composite material's excellent surface-enhanced Raman spectroscopy (SERS) enhancement capabilities and good signal reproducibility. Furthermore, the COF-Au@Ag composite material possesses abundant functional groups such as benzene rings, imino groups, and vinyl groups. Since novel pollutants like antibiotics and microplastics contain active sites such as benzene rings, carboxyl groups, and amino groups, strong hydrophobic, electrostatic, π-π, and hydrogen bonding interactions can occur between them, further enhancing the adsorption and enrichment capabilities for these pollutants. Using the COF-Au@Ag composite material as a surface-enhanced Raman spectroscopy (SERS) substrate, it can be used for the efficient enrichment and sensitive detection of trace antibiotics and microplastics in complex plant samples, exhibiting high detection sensitivity with detection limits as low as 0.002 mg / L. -1 and 0.029 mg / L -1 It is expected to find wide application in the field of trace analysis of new pollutants.
[0056] Example 2
[0057] Example 2 of this application discloses a method for preparing a covalent organic framework nanocomposite material, which differs from the example in that:
[0058] In step five, Ag in the silver nitrate solution + With AuCl4 - The molar ratio is 40:1.
[0059] Example 3
[0060] Example 3 of this application discloses a method for preparing a covalent organic framework nanocomposite material, which differs from the example in that:
[0061] In step five, Ag in the silver nitrate solution + With AuCl4- The molar ratio is 60:1.
[0062] Example 4
[0063] Example 4 of this application discloses a method for preparing a covalent organic framework nanocomposite material, which differs from the example in that:
[0064] In step five, Ag in the silver nitrate solution + With AuCl4 - The molar ratio is 80:1.
[0065] Example 5
[0066] Example 5 of this application discloses a method for preparing a covalent organic framework nanocomposite material, which differs from the example in that:
[0067] In step five, Ag in the silver nitrate solution + With AuCl4 - The molar ratio is 120:1.
[0068] Example 6
[0069] Example 6 of this application discloses a method for preparing a covalent organic framework nanocomposite material, which differs from the example in that:
[0070] In step five, Ag in the silver nitrate solution + With AuCl4 - The molar ratio is 200:1.
[0071] Transmission electron microscopy (TEM) images of the COF-Au@Ag composite materials obtained in Examples 1, 2, and 6 are shown below. Figure 3 As shown in the results, COF-Au@Ag composite materials with different particle sizes of silver nanoparticles can be obtained under different Ag:Au molar ratios. Overall, the distribution of silver nanoparticles is relatively uniform. However, as the Ag:Au molar ratio increases from 40:1 to 200:1, the particle size of silver nanoparticles in the COF-Au@Ag composite material gradually increases. When the Ag:Au molar ratio reaches 200:1, due to the excessively large size of the silver nanoparticles, some of the silver nanoparticles come into contact with each other, which is not conducive to the generation of surface-reinforced Raman enhancement hotspots.
[0072] Application Example 1
[0073] Example 1 of this application discloses a method for detecting the probe molecule mercaptobenzoic acid. The COF-Au@Ag composite material dispersions obtained in Examples 1-6 are mixed in equal volumes with mercaptobenzoic acid solutions. The mixture is vortexed for 50-70 seconds (preferably 1 minute), allowed to stand for 8-12 minutes (preferably 10 minutes), and then dropped onto a glass slide. The slide is then placed under the probe of a fiber optic Raman spectrometer for Raman detection. The Raman spectrometer detection conditions are as follows: laser wavelength 785 nm, laser intensity 50 mW, integration time 1 s, integration times 20, and different sampling points are randomly selected for each sample, with at least 10 samplings. The obtained spectra are averaged to obtain the final Raman spectrum of the sample.
[0074] The amount of COF-Au@Ag composite material dispersion used was 0.5 mL, and the concentration of mercaptobenzoic acid solution was 0.1 mg / L. -1 The solution contains mercaptobenzoic acid, and the amount of antibiotic solution used is 0.5 mL.
[0075] Application Example 1: Using various COF-Au@Ag composite materials for 0.1 mg / L -1 The results of the mercaptobenzoic acid test are as follows Figure 4 As shown, as the Ag:Au molar ratio increased from 40:1 to 200:1, the Raman spectral signal of mercaptobenzoic acid showed a trend of first increasing and then decreasing. The best reinforcement effect was obtained when the Ag:Au molar ratio was 100:1. The above results indicate that the appropriate amount of nano-silver is very important for producing a good reinforcement effect. When the Ag:Au molar ratio is 100:1, the COF-Au@Ag composite material has the best surface-reinforced Raman reinforcement performance.
[0076] Application Example 2
[0077] Example 3 of this application discloses a method for trace detection of antibiotics. The COF-Au@Ag composite material dispersion obtained in Example 1 is mixed with an antibiotic solution of equal volume, vortexed for 50-70 seconds (preferably 1 minute), and allowed to stand for 8-12 minutes (preferably 10 minutes). The mixture is then dropped onto a glass slide and placed under the probe of a fiber optic Raman spectrometer for Raman detection. The Raman spectrometer detection conditions are as follows: laser wavelength 785 nm, laser intensity 50 mW, integration time 1 s, integration times 20, and different sampling points are randomly selected for each sample, with at least 10 samples collected. The obtained spectra are averaged to obtain the final Raman spectrum of the sample.
[0078] The amount of COF-Au@Ag composite material dispersion used was 0.5 mL, and the concentration of sulfamethoxazole solution was 0.1 mg / L. -1 The amount of sulfamethoxazole solution used was 0.5 mL.
[0079] The results of using COF-Au@Ag composite material for the detection of sulfamethoxazole solutions of different concentrations are as follows: Figure 5 As shown, the characteristic Raman signal of sulfamethoxazole gradually decreased with decreasing concentration. The COF-Au@Ag composite material exhibited good detection sensitivity for sulfamethoxazole, with a detection limit as low as 0.002 mg / L. -1 Among them, 1600cm -1 Using the characteristic peak intensity at a certain point as a reference, and taking the characteristic peak of the COF-Au@Ag composite material itself (1400 cm⁻¹) as an example, -1 () is the internal standard, peak intensity ratio I 1600 / I 1400 A good linear relationship exists between the COF-Au@Ag composite material and the logarithm of the sulfamethoxazole concentration, indicating that the COF-Au@Ag composite material can be used for sensitive quantitative detection (i.e., trace detection) of sulfamethoxazole.
[0080] Application Example 3
[0081] Example 3 of this application discloses a trace detection method for microplastics. The COF-Au@Ag composite material dispersion obtained in Example 1 is mixed with microplastic dispersions of different mass fractions in equal volumes, vortexed for 50-70 seconds (preferably 1 minute), and allowed to stand for 8-12 minutes (preferably 10 minutes). The mixture is then dropped onto a glass slide and placed under the probe of a fiber optic Raman spectrometer for Raman detection. The Raman spectrometer detection conditions are as follows: laser wavelength 785nm, laser intensity 50mW, integration time 1s, integration times 20, and different sampling points are randomly selected for each sample, with at least 10 collections. The obtained spectra are averaged to obtain the final Raman spectrum of the sample.
[0082] The amount of COF-Au@Ag composite material dispersion used was 0.5 mL, and the microplastic dispersion was a polystyrene microdispersion with a concentration of 0.001-1 mg / L. -1 The concentration of the microplastic dispersion was 0.5 mL.
[0083] The results of the detection of COF-Au@Ag composite material in microplastic dispersions with different mass fractions are as follows: Figure 6 As shown, the characteristic Raman signal gradually decreased with decreasing mass fraction of the microplastic dispersion. The COF-Au@Ag composite material exhibited good detection sensitivity for microplastic dispersions, with a detection limit as low as 0.002 mg / L. -1 Among them, 1600cm -1 Using the characteristic peak intensity at a certain point as a reference, and taking the characteristic peak of the COF-Au@Ag composite material itself (1400 cm⁻¹) as an example, -1 () is the internal standard, peak intensity ratio I 1600 / I 1400A good linear relationship exists between the COF-Au@Ag composite material and the logarithm of the mass fraction of the microplastic dispersion, indicating that the COF-Au@Ag composite material can be used for sensitive quantitative detection (i.e., trace detection) of microplastic dispersions.
[0084] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.
Claims
1. A method for preparing a covalent organic framework nanocomposite material, characterized in that, Includes the following steps: Step 1, Monomer Dissolution: At room temperature, 1,3,5-tris(4-aminophenyl)benzene and 2,5-divinylterephthalaldehyde monomers are dissolved separately in organic solvents by sonication. Acetic acid is then slowly added dropwise to the two solutions under sonication conditions to obtain solution A and solution B. Step 2, Mixing and centrifugation precipitation: After mixing solution A and solution B evenly, let them stand for 60-80 hours to obtain mixture A. Then, mix solution A is thoroughly stirred, precipitated and centrifuged to obtain precipitate A. Step 3, washing and drying: precipitate A is washed multiple times to obtain precipitate C. Finally, precipitate C is dried at 55-65℃ under vacuum to obtain flower-shaped COF material. Step 4, Gold and Silver Ion Reaction: The flower-shaped COF material is dispersed in ultrapure water under ultrasonic conditions to obtain a COF material dispersion. During stirring, HAuCl4 solution is added dropwise to the COF material dispersion, and stirring is continued for 20-40 minutes to obtain a COF-Au composite material dispersion. Step 5, Composite Material Dispersion: Add sodium citrate to the COF-Au composite material dispersion, stir at 60-80℃ for 4-6 minutes, then slowly add silver nitrate solution, wherein the silver nitrate solution contains Ag. + With AuCl4 - With a molar ratio of 60:1-100:1, the reaction is continued for 50-70 minutes to obtain a COF-Au@Ag composite material dispersion, which is a covalent organic framework nano-noble metal composite material.
2. The method for preparing the covalent organic framework nanocomposite material according to claim 1, characterized in that, In step one, the molar ratio of the two monomers, 1,3,5-tris(4-aminophenyl)benzene and 2,5-divinyl terephthalaldehyde, is 2:3, wherein the amount of 1,3,5-tris(4-aminophenyl)benzene monomer used is 0.04 mmol, the amount of 2,5-divinyl terephthalaldehyde monomer used is 0.06 mmol, and the amount of acetic acid used is 0.6-2 mL.
3. The method for preparing the covalent organic framework nanocomposite material according to claim 2, characterized in that, In step one, the organic solvent is acetonitrile, and the amount of acetonitrile used is 4-6 mL.
4. The method for preparing the covalent organic framework nanocomposite material according to claim 1, characterized in that, In step three, precipitate A is first washed with tetrahydrofuran to obtain precipitate B, and then precipitate B is washed a second time with ethanol to remove unreacted monomers to obtain precipitate C.
5. The method for preparing the covalent organic framework nanocomposite material according to claim 1, characterized in that, In step four, the amount of flower-shaped COF material used is between 20-30 mg, the concentration of HAuCl4 solution is between 0.6-2.5%, the total volume of HAuCl4 solution used is between 25-200 μL, and the amount of ultrapure water used is between 8-12 mL.
6. The method for preparing the covalent organic framework nanocomposite material according to claim 1, characterized in that, In step five, the amount of sodium citrate used is between 32 and 38 mg.
7. The method for preparing the covalent organic framework nanocomposite material according to claim 6, characterized in that, In step five, the silver nitrate solution is added at a rate of 0.4-0.6 mL per minute.
8. A covalent organic framework nanocomposite material, characterized in that, It is prepared by any one of claims 1-7.
9. A method for trace detection of antibiotics, characterized in that, The COF-Au@Ag composite material dispersion prepared by any one of claims 1-7 was mixed with an antibiotic solution of equal volume, vortexed for 50-70 seconds, and allowed to stand for 8-12 minutes. The mixture was then dropped onto a glass slide and placed under the probe of a fiber optic Raman spectrometer for Raman detection. The Raman spectrometer detection conditions were as follows: laser wavelength 785 nm, laser intensity 50 mW, integration time 1 s, integration times 20, and different sampling points were randomly selected for each sample, with at least 10 samples collected. The obtained spectra were averaged to obtain the final Raman spectrum of the sample.
10. A method for detecting microplastics, characterized in that, The COF-Au@Ag composite material dispersion prepared by any one of claims 1-7 is mixed with an equal volume of microplastic dispersion, vortexed for 50-70 seconds, and allowed to stand for 8-12 minutes. The mixture is then dropped onto a glass slide and placed under the probe of a fiber optic Raman spectrometer for Raman detection. The Raman spectrometer detection conditions are as follows: laser wavelength 785 nm, laser intensity 50 mW, integration time 1 s, integration times 20, and different sampling points are randomly selected for each sample, with at least 10 samples collected. The obtained spectra are averaged to obtain the final Raman spectrum of the sample.