Molecularly imprinted magnetic covalent organic framework nano material as well as preparation method and application thereof

Abstract

The invention discloses a preparation method of a molecularly imprinted magnetic covalent organic framework nano-material, which comprises the following steps: adding Fe3O4 nano-particles, ethyl carbamate, substituted triazine aromatic amine, 2, 4, 6-trihydroxy trimesic aldehyde and 1, 3, 5-triazine-2, 4, 6-tricarboxaldehyde into dimethyl sulfoxide, mixing, then adding anhydrous acetic acid, stirring and reacting at room temperature, filtering, washing, and drying to obtain the molecularly imprinted magnetic covalent organic framework nano-material. After the reaction is finished, carrying out magnetic separation to obtain Fe3O4 (at) COFs; washing the Fe3O4 (at) COFs with an ethanol solution, washing the Fe3O4 (at) COFs with water, and drying the washed Fe3O4 (at) COFs to obtain a molecularly imprinted magnetic covalent organic framework nano material MIPs-Fe3O4 (at) COFs; compared with the prior art, after the prepared MIPs-Fe3O4-coated COFs are repeatedly used for 10 times, the removal efficiency of the prepared MIPs-Fe3O4-coated COFs on ethyl carbamate still can reach 97% or above, and the removal efficiency of the prepared MIPs-Fe3O4-coated COFs on ethyl carbamate is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of nanomaterial preparation, and in particular to a molecularly imprinted magnetic covalent organic framework nanomaterial, a preparation method and application thereof. Background Art

[0002] In recent years, food safety has become increasingly important. Ethyl carbamate is a toxic byproduct of alcoholic beverages, inevitably produced during fermentation and storage through metabolic and side effects. It is carcinogenic and teratogenic, posing a potential risk to human health. Consequently, the issue of ethyl carbamate in alcoholic beverages has drawn industry attention and become a new challenge for the industry.

[0003] For example, CN118217949A discloses an application of a magnetic covalent organic framework nanomaterial, wherein the magnetic covalent organic framework nanomaterial is used as an extractant for removing ethyl carbamate from wine.

[0004] The method for preparing the magnetic covalent organic framework nanomaterial comprises the following steps:

[0005] Preparation of magnetic Fe3O4 nanoparticles;

[0006] Modified magnetic Fe3O4 nanoparticles are prepared based on magnetic Fe3O4 nanoparticles;

[0007] The reaction system is prepared by reacting ethanol, water, ammonia water and ethyl silicate at a temperature of 20-40°C, and then the prepared modified magnetic Fe3O4 nanoparticles are added to the reaction system to continue the reaction. After the reaction is completed, the Fe3O4@SiO2 nanoparticles are obtained by washing and drying.

[0008] The obtained Fe3O4@SiO2 nanoparticles were used as the basis to prepare magnetic covalent organic framework nanomaterials Fe3O4@SiO2@COFs.

[0009] Although the magnetic covalent organic framework nanomaterial Fe3O4@SiO2@COFs prepared above can effectively remove ethyl carbamate from wine, its removal efficiency needs to be further improved. Summary of the Invention

[0010] In view of the deficiencies in the prior art, the purpose of the present invention is to provide a molecularly imprinted magnetic covalent organic framework nanomaterial and its preparation method and application, so as to solve the problem in the prior art that the removal efficiency of the currently prepared magnetic covalent organic framework nanomaterial for ethyl carbamate in wine needs to be improved.

[0011] To achieve the above objectives, the first aspect of the present invention adopts the following technical solution: a method for preparing a molecularly imprinted magnetic covalent organic framework nanomaterial, comprising the following steps:

[0012] Fe3O4 nanoparticles, ethyl carbamate, substituted triazine aromatic amine, 2,4,6-trihydroxybenzene trimesic acid, and 1,3,5-triazine-2,4,6-tricarboxaldehyde were added to dimethyl sulfoxide and mixed. Anhydrous acetic acid was then added to react at room temperature with stirring. After the reaction, Fe3O4@COFs were obtained by magnetic separation.

[0013] After Fe3O4@COFs was washed with ethanol solution, water and dried, molecularly imprinted magnetic covalent organic framework nanomaterials MIPs-Fe3O4@COFs were obtained.

[0014] Technical principle:

[0015] The present invention uses the target molecule ethyl carbamate as the template molecule, and through an in situ self-assembly method, gives full play to the high specific selectivity of molecular imprinting technology and the high adsorption of COFs materials, and utilizes the electrostatic attraction, hydrogen bond and other forces between the template molecule and the COF raw material to prepare a magnetic COFs material coated with the template molecule; further, the template ethyl carbamate molecule is eluted by a solvent, which promotes the generation of three-dimensional imprinted pores in the COFs material, thereby preparing a MIPs-Fe3O4@COFs material with high selectivity and high adsorption performance; wherein, the substituted triazine aromatic amine can improve the flexible encapsulation of ethyl carbamate by the COFs material through the flexible double bond bridging of the triazine ring and the benzene ring, which helps to enhance the formation of the molecular imprinting cavity structure; and, since the triazine ring of the 1,3,5-triazine-2,4,6-triformaldehyde molecule is an electron-deficient aromatic ring, it can increase the positive charge of the aldehyde group, thereby improving the COFs polymerization reaction process, and further regulating the spatial structure of the COFs material.

[0016] Furthermore, the molecular structure of the substituted triazine aromatic amine is:

[0017]

[0018] Wherein, n=1 or 2.

[0019] Furthermore, the mass ratio of the Fe3O4 nanoparticles, substituted triazine aromatic amine, 2,4,6-trihydroxypyromellitic aldehyde and 1,3,5-triazine-2,4,6-tricarboxaldehyde is 1-3.8:0.5-3.5:0.25-1.5:0.1-0.5;

[0020] The mass ratio of the urethane to the substituted triazine aromatic amine is 0.1 to 0.35:1;

[0021] The amount of Fe3O4 nanoparticles added is 0.1 to 0.38 g for each 50 ml of dimethyl sulfoxide added;

[0022] The amount of anhydrous acetic acid added is 15-50 mL for every 1 g of Fe3O4 nanoparticles added.

[0023] Furthermore, the particle size of the Fe3O4 nanoparticles is 100-300nm.

[0024] Furthermore, the mass content of the solute in the ethanol solution is 75%.

[0025] The second aspect of the present invention adopts the following technical solution: a molecularly imprinted magnetic covalent organic framework nanomaterial is prepared by the preparation method of a molecularly imprinted magnetic covalent organic framework nanomaterial described in the first aspect of the present invention.

[0026] Furthermore, the molecularly imprinted magnetic covalent organic framework nanomaterial is a spherical particle structure, specifically Fe3O4 nanoparticles and a covalent organic framework with urethane molecular imprinting wrapped on the surface of the Fe3O4 nanoparticles.

[0027] Furthermore, the particle size of the molecularly imprinted magnetic covalent organic framework nanomaterial ranges from 200 to 600 nm.

[0028] The third aspect of the present invention adopts the following technical solution: the application of a molecularly imprinted magnetic covalent organic framework nanomaterial as an extractant to remove ethyl carbamate from wine.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. The present invention uses ethyl carbamate as the target molecule as the template molecule, and through the template self-assembly method, gives full play to the high specificity of molecular imprinting technology and the high adsorption of COFs materials;

[0031] 2. The prepared MIPs-Fe3O4@COFs skeleton molecular structure contains relatively abundant nitrogen and oxygen lone-pair electrons, which can make the material surface have more negative charges. The target ethyl carbamate is weakly alkaline in solution and has a positive surface charge. This can further enhance the directional adsorption ability of the MIPs-Fe3O4@COFs material for ethyl carbamate, and bring out the material's specific adsorption properties.

[0032] 3. The raw material monomer substituted triazine aromatic amine molecules in the MIPs-Fe3O4@COFs material prepared by the present invention have abundant amino groups, good molecular structure symmetry, and abundant polymerization reaction sites. The combination with 1,3,5-triazine-2,4,6-tricarbaldehyde can enhance and regulate the spatial structure of the MIPs-Fe3O4@COFs material, thereby improving the adsorption performance of the MIPs-Fe3O4@COFs material for ethyl formate.

[0033] 4. The prepared MIPs-Fe3O4@COFs material has excellent properties such as large specific surface area, rich spatial structure, and abundant adsorption sites. It can achieve efficient adsorption and separation under the premise of high specificity and high adsorption capacity.

[0034] 5. After being reused 10 times, the MIPs-Fe3O4@COFs material of the present invention can still achieve a removal efficiency of ethyl formate of more than 97%. DETAILED DESCRIPTION

[0035] The present invention will be further described in detail below through specific embodiments:

[0036] Example 1

[0037] Five substances, including 0.1g Fe3O4 nanoparticles, 0.025g ethyl carbamate, 0.1g substituted triazine aromatic amine, 0.05g 2,4,6-trihydroxybenzene trimesic acid, and 0.03g 1,3,5-triazine-2,4,6-tricarboxaldehyde, were mixed in 50mL dimethyl sulfoxide, and then 4mL anhydrous acetic acid was added. The mixture was stirred at room temperature for 24h. After the reaction, magnetic separation was performed to obtain Fe3O4@COFs. Subsequently, the template molecule ethyl carbamate of the Fe3O4@COFs material was washed with 75% ethanol solution. The material was then washed with water and dried to obtain molecularly imprinted magnetic covalent organic framework nanomaterial MIPs-Fe3O4@COFs.

[0038] The molecular structure of the substituted triazine aromatic amine is:

[0039]

[0040] Where n=1.

[0041] The particle size of the Fe3O4 nanoparticles is 180nm.

[0042] The MIPs-Fe3O4@COFs has a spherical particle structure and a particle size of 350 nm.

[0043] The prepared MIPs-Fe3O4@COFs was used as an extractant to remove ethyl carbamate from wine. The detection equipment in this example was a comprehensive two-dimensional gas chromatography-quadrupole time-of-flight high-resolution mass spectrometer. Specifically:

[0044] (1) Preparation of standard solution: Accurately weigh 100 mg of ethyl carbamate into a 100 mL volumetric flask, dissolve it in methanol and dilute to volume to obtain a 1.0 mg / mL stock solution. Store in a refrigerator at 4°C until use. The working concentrations for the standard curve are 2 μg / mL, 1.5 μg / mL, 1.2 μg / mL, 0.8 μg / mL, 0.5 μg / mL, 0.1 μg / mL, and 0.05 μg / mL.

[0045] (2) Pretreatment of liquor samples: Liquor samples of different flavors were diluted with ultrapure water at a ratio of 1:6 to reduce matrix interference before the extraction process;

[0046] (3) Magnetic solid-phase adsorption: MIPs-Fe3O4@COFs was mixed with a wine sample, where the mass ratio of the wine sample volume to the MIPs-Fe3O4@COFs was 1 ml:2 mg. After adsorption and standing for 20 min, the mixture was eluted with n-hexane, the eluent was discarded, and then eluted with 25 mL of 5% ethyl acetate-ether solution (a 5% solution prepared with ethyl acetate as the solute and ether as the solvent). The eluent was collected and blown to near dryness with nitrogen.

[0047] The MIPs-Fe3O4@COFs prepared in this example removed ethyl carbamate (the concentration was 1.0 μg / mL, 1 mL of standard sample), and the removal efficiency of ethyl carbamate reached 98.2%. After 10 cycles of use, the removal efficiency of ethyl carbamate reached more than 97.4% (the concentration was 1.0 μg / mL, 1 mL of standard sample).

[0048] 1 mL of the treated 5 different liquor samples was taken and then spiked with ethyl carbamate at a concentration of 1 μg / mL. After magnetic solid phase adsorption, the removal efficiency of ethyl carbamate reached more than 97%.

[0049] Example 2

[0050] Five substances, 0.1g Fe3O4 nanoparticles, 0.1g ethyl carbamate, 0.3g substituted triazine aromatic amine, 0.12g 2,4,6-trihydroxybenzene trimesic acid, and 0.05g 1,3,5-triazine-2,4,6-triformaldehyde, were mixed in 50mL dimethyl sulfoxide, and then 5mL anhydrous acetic acid was added. The mixture was stirred at room temperature for 36h. After the reaction, magnetic separation was performed to obtain Fe3O4@COFs; then, the template molecule ethyl carbamate of the Fe3O4@COFs material was washed with 75% ethanol solution; then the molecularly imprinted magnetic covalent organic framework nanomaterial MIPs-Fe3O4@COFs was obtained by washing with water and drying.

[0051] The molecular structure of the substituted triazine aromatic amine is:

[0052]

[0053] Where n=2.

[0054] The particle size of the Fe3O4 nanoparticles is 210 nm.

[0055] The MIPs-Fe3O4@COFs has a spherical particle structure and a particle size of 600 nm.

[0056] The prepared MIPs-Fe3O4@COFs was used as an extractant to remove ethyl carbamate from wine, and the specific implementation steps and methods were the same as those in Example 1.

[0057] The MIPs-Fe3O4@COFs prepared in this example removed ethyl carbamate (the concentration was 1.0 μg / mL, 1 mL of standard sample), and the removal efficiency of ethyl carbamate reached 97.9%. After 10 cycles of use, the removal efficiency of ethyl carbamate reached more than 97.2% (the concentration was 1.0 μg / mL, 1 mL of standard sample).

[0058] 1 mL of the treated 5 different liquor samples was taken and then spiked with ethyl carbamate at a concentration of 1 μg / mL. After magnetic solid phase adsorption, the removal efficiency of ethyl carbamate reached more than 97%.

[0059] Example 3

[0060] 0.38g Fe3O4 nanoparticles, 0.005g ethyl carbamate, 0.05g substituted triazine aromatic amine, 0.025g 2,4,6-trihydroxybenzene trimesic acid, and 0.01g 1,3,5-triazine-2,4,6-triformaldehyde were mixed in 50mL dimethyl sulfoxide, and then 5.7mL anhydrous acetic acid was added. The mixture was stirred at room temperature for 30h. After the reaction, magnetic separation was performed to obtain Fe3O4@COFs. Subsequently, the template molecule ethyl carbamate of the Fe3O4@COFs material was washed with 75% ethanol solution. The material was then washed with water and dried to obtain molecularly imprinted magnetic covalent organic framework nanomaterial MIPs-Fe3O4@COFs.

[0061] The molecular structure of the substituted triazine aromatic amine is:

[0062]

[0063] Where n=2.

[0064] The particle size of the Fe3O4 nanoparticles is 100 nm.

[0065] The MIPs-Fe3O4@COFs has a spherical particle structure and a particle size of 200 nm.

[0066] The prepared MIPs-Fe3O4@COFs was used as an extractant to remove ethyl carbamate from wine, and the specific implementation steps and methods were the same as those in Example 1.

[0067] The MIPs-Fe3O4@COFs prepared in this example removed ethyl carbamate (the concentration was 1.0 μg / mL, 1 mL of standard sample), and the removal efficiency of ethyl carbamate reached 97.8%. After 10 cycles of use, the removal efficiency of ethyl carbamate reached more than 97.1% (the concentration was 1.0 μg / mL, 1 mL of standard sample).

[0068] 1 mL of the treated 5 different liquor samples was taken and then spiked with ethyl carbamate at a concentration of 1 μg / mL. After magnetic solid phase adsorption, the removal efficiency of ethyl carbamate reached more than 97%.

[0069] Example 4

[0070] Five substances, 0.22g Fe3O4 nanoparticles, 0.1g ethyl carbamate, 0.21g substituted triazine aromatic amine, 0.1g 2,4,6-trihydroxybenzene trimesic acid, and 0.025g 1,3,5-triazine-2,4,6-tricarbaldehyde, were mixed in 50mL dimethyl sulfoxide, and then 6.6mL anhydrous acetic acid was added. The mixture was stirred at room temperature for 28h. After the reaction, magnetic separation was performed to obtain Fe3O4@COFs; then, the template molecule ethyl carbamate of the Fe3O4@COFs material was washed with 75% ethanol solution; then the mixture was washed with water and dried to obtain molecularly imprinted magnetic covalent organic framework nanomaterial MIPs-Fe3O4@COFs.

[0071] The molecular structure of the substituted triazine aromatic amine is:

[0072]

[0073] Where n=1.

[0074] The particle size of the Fe3O4 nanoparticles is 160nm.

[0075] The MIPs-Fe3O4@COFs has a spherical particle structure and a particle size of 280 nm.

[0076] The prepared MIPs-Fe3O4@COFs was used as an extractant to remove ethyl carbamate from wine, and the specific implementation steps and methods were the same as those in Example 1.

[0077] The MIPs-Fe3O4@COFs prepared in this example removed ethyl carbamate (the concentration was 1.0 μg / mL, 1 mL of standard sample), and the removal efficiency of ethyl carbamate reached 98.2%. After 10 cycles of use, the removal efficiency of ethyl carbamate reached more than 97.4% (the concentration was 1.0 μg / mL, 1 mL of standard sample).

[0078] 1 mL of the treated 5 different liquor samples was taken and then spiked with ethyl carbamate at a concentration of 1 μg / mL. After magnetic solid phase adsorption, the removal efficiency of ethyl carbamate reached more than 97%.

[0079] Comparative Example 1

[0080] The only difference from Example 1 is that ethyl carbamate is not added to obtain the magnetic covalent organic framework nanomaterial.

[0081] The prepared magnetic covalent organic framework nanomaterial is used as an extractant to remove ethyl carbamate from wine, and the specific implementation steps and methods are the same as those in Example 1.

[0082] The magnetic covalent organic framework nanomaterial prepared in this embodiment removes ethyl carbamate (the concentration is 1.0 μg / mL, 1 mL standard sample), and the removal efficiency of ethyl carbamate reaches 92%. After 10 cycles of use, the removal efficiency of ethyl carbamate is 87% (the concentration is 1.0 μg / mL, 1 mL standard sample).

[0083] 1 mL of the treated 5 different liquor samples was taken and then spiked with ethyl carbamate at a concentration of 1 μg / mL. After magnetic solid phase adsorption, the removal efficiency of ethyl carbamate was about 87%.

[0084] Comparative Example 2

[0085] The only difference from Example 1 is that the substituted triazine aromatic amine is replaced by 1,3,5-triazine-2,4,6-tricarbaldehyde to obtain a molecularly imprinted magnetic covalent organic framework nanomaterial.

[0086] The molecularly imprinted magnetic covalent organic framework nanomaterial prepared in this comparative example removed ethyl carbamate (the concentration was 1.0 μg / mL, 1 mL standard sample), and the removal efficiency of ethyl carbamate was 89.6%. After 10 cycles of use, the removal efficiency of ethyl carbamate was 87.3% (the concentration was 1.0 μg / mL, 1 mL standard sample).

[0087] 1 mL of the treated 5 different liquor samples was taken and then spiked with ethyl carbamate at a concentration of 1 μg / mL. After magnetic solid phase adsorption, the removal efficiency of ethyl carbamate was around 84.8%.

[0088] Comparative Example 3

[0089] The only difference from Example 1 is that 1,3,5-triazine-2,4,6-tricarboxaldehyde is replaced by terephthalaldehyde to obtain a molecularly imprinted magnetic covalent organic framework nanomaterial.

[0090] The molecularly imprinted magnetic covalent organic framework nanomaterial prepared in this comparative example removed ethyl carbamate (the concentration was 1.0 μg / mL, 1 mL standard sample), and the removal efficiency of ethyl carbamate was 86.7%. After 10 cycles of use, the removal efficiency of ethyl carbamate was 82.1% (the concentration was 1.0 μg / mL, 1 mL standard sample).

[0091] 1 mL of the treated 5 different liquor samples was taken and then spiked with ethyl carbamate at a concentration of 1 μg / mL. After magnetic solid phase adsorption, the removal efficiency of ethyl carbamate was around 81.7%.

[0092] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method for preparing a molecularly imprinted magnetic covalent organic framework nanomaterial, characterized in that: The following steps are involved: Fe3O4 nanoparticles, ethyl carbamate, substituted triazine aromatic amine, 2,4,6-trihydroxybenzene-trialdehyde and 1,3,5-triazine-2,4,6-tricarbaldehyde were added to dimethyl sulfoxide and mixed, and then anhydrous acetic acid was added to stir the reaction at room temperature. After the reaction, Fe3O4@COFs were obtained by magnetic separation. After Fe3O4@COFs was washed with ethanol solution, water and dried, molecularly imprinted magnetic covalent organic framework nanomaterials MIPs-Fe3O4@COFs were obtained.

2. The method for preparing a molecularly imprinted magnetic covalent organic framework nanomaterial according to claim 1, characterized in that: The molecular structure of the substituted triazine aromatic amine is: Wherein, n=1 or 2.

3. The method for preparing a molecularly imprinted magnetic covalent organic framework nanomaterial according to claim 1 or 2, characterized in that: The mass ratio of the Fe3O4 nanoparticles, substituted triazine aromatic amine, 2,4,6-trihydroxybenzene trimesic acid and 1,3,5-triazine-2,4,6-tricarbaldehyde is 1-3.8:0.5-3.5:0.25-1.5:0.1-0.5; The mass ratio of the urethane to the substituted triazine aromatic amine is 0.1 to 0.35:1; The amount of Fe3O4 nanoparticles added is 0.1-0.38 g for each 50 ml of dimethyl sulfoxide added; When 1 g of the Fe3O4 nanoparticles is added, the amount of anhydrous acetic acid added is 15 to 50 mL.

4. The method for preparing a molecularly imprinted magnetic covalent organic framework nanomaterial according to claim 1, characterized in that: The Fe3O4 nanoparticles have a particle size of 100-300nm.

5. The method for preparing a molecularly imprinted magnetic covalent organic framework nanomaterial according to claim 1, characterized in that: The mass content of the solute in the ethanol solution is 75%.

6. A molecularly imprinted magnetic covalent organic framework nanomaterial, characterized in that: The material is prepared by the method for preparing a molecularly imprinted magnetic covalent organic framework nanomaterial according to any one of claims 1 to 5.

7. The molecularly imprinted magnetic covalent organic framework nanomaterial according to claim 6, characterized in that: The molecular imprinted magnetic covalent organic framework nanomaterial is a spherical particle structure.

8. The molecularly imprinted magnetic covalent organic framework nanomaterial according to claim 6, characterized in that: The particle size range of the molecular imprinted magnetic covalent organic framework nanomaterial is 200-600nm.

9. An application of a molecularly imprinted magnetic covalent organic framework nanomaterial, characterized in that: Used as an extractant to remove ethyl carbamate from wine.

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