A Schiff base functionalized silica aerogel / benzo(a)pyrene molecularly imprinted material and its application

Abstract

The present invention discloses a Schiff base functionalized silica aerogel / benzo(a)pyrene molecular imprinting material and its application. Pyrene is added to the Schiff base functionalized silica aerogel as a virtual template molecule; functional monomers, a cross-linking agent and an initiator are added; and the Schiff base functionalized silica aerogel / benzo(a)pyrene molecular imprinting material is prepared by a surface imprinting polymerization method. The present invention utilizes silica aerogel as a substrate, and its porous structure and high porosity enhance the adsorption efficiency of benzo(a)pyrene. The introduction of Schiff base groups forms a strong interaction with benzo(a)pyrene molecules, further improving the adsorption capacity. Combined with molecular imprinting technology, pores that are highly matched with benzo(a)pyrene are formed on the surface of the Schiff base functionalized aerogel, giving the material high selectivity. The use of pyrene as a virtual template avoids the use of benzo(a)pyrene, reducing environmental risks and material costs.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and in particular relates to a Schiff base functionalized silica aerogel / benzo(a)pyrene molecular imprinting material and an application thereof. Background Art

[0002] Benzo(a)pyrene (B(a)P) is a polycyclic aromatic hydrocarbon (PAH) compound widely considered one of the world's most potent carcinogens. B(a)P is primarily produced during high-temperature roasting, smoking, leaching, and pressing processes. These processes cause thermal cracking, cyclization, and polymerization of fats, cholesterol, proteins, and carbohydrates. Ingestion can lead to lung cancer, liver cancer, and gastrointestinal cancer. To ensure food safety, my country's "National Food Safety Standard for Limits of Contaminants in Food" (GB2762-2017) stipulates a limit of 10 μg / kg for B(a)P in vegetable oils. However, the processing of many vegetable oils, such as the pressing of sesame, linseed, and rapeseed oils, requires high-temperature roasting of the seeds. Improper temperature control can easily result in B(a)P levels exceeding national standards. This further highlights the importance of detecting B(a)P in vegetable oils.

[0003] Traditional solid-phase extraction (SPE) columns used in detection have poor selectivity and are difficult to detect trace amounts of target compounds in complex matrices. Therefore, a Schiff base-functionalized silica aerogel / benzo(a)pyrene molecularly imprinted material and its application are urgently needed. Summary of the Invention

[0004] To address the deficiencies in the prior art, the present invention provides a Schiff base-functionalized silica aerogel / benzo(a)pyrene molecularly imprinted material and its application. Combining the chemical activity of the Schiff base group, the high specific surface area and porous structure of the silica aerogel, and the selective imprinting capability of molecular imprinting technology, the material forms a multifunctional new adsorption material with the advantages of convenient operation, low reagent consumption, high purification effect, and few interfering chromatographic peaks, making it suitable for processing large quantities of samples.

[0005] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0006] The first object of the present invention is to provide a Schiff base functionalized silica aerogel / benzo(a)pyrene molecularly imprinted material, wherein the imprinted material is prepared by the following steps:

[0007] S1. Preparation of Schiff base functionalized silica aerogel:

[0008] S11, dissolving 3-aminopropyltriethoxysilane in ethanol, then slowly adding 2,5-divinylterephthalaldehyde dissolved in ethanol, stirring to react, to obtain solution A;

[0009] S12, dissolving tetraethyl orthosilicate in a mixed solution of ethanol and 0.1 mol / L HCl, stirring to react, to obtain solution B;

[0010] S13, slowly adding the solution A obtained in step S11 to the solution B obtained in step S12, stirring for reaction, adding 1 mol / L ammonia water to adjust the pH to 7, continuing stirring, and forming a gel in a water bath;

[0011] S14, performing a solvent exchange with anhydrous ethanol, and then performing a solvent exchange with n-hexane;

[0012] S15, placing the solvent-exchanged sample in a vacuum drying oven to dry, thereby obtaining a Schiff base-functionalized silica aerogel;

[0013] S2. Preparation of Schiff base functionalized silica aerogel / benzo(a)pyrene molecularly imprinted material:

[0014] S21, dissolving pyrene in acetonitrile, adding Schiff base functionalized silica aerogel, stirring to react, so that pyrene and Schiff base groups are prepolymerized;

[0015] S22, adding functional monomers, crosslinking agents and initiators to the prepolymer solution of step S21, and performing free radical polymerization in a water bath under nitrogen protection;

[0016] S23, centrifuging the product obtained after the reaction in step S22, washing with acetonitrile; eluting the product with dichloromethane to remove the template molecules; and vacuum drying the product to obtain a Schiff base functionalized silica aerogel / benzo(a)pyrene molecularly imprinted material.

[0017] Preferably, the step S11 is stirred at 30-35° C. for 6-8 hours, the step S12 is stirred at 60-65° C. for 2-4 hours, and the mass ratio of tetraethyl orthosilicate, 3-aminopropyltriethoxysilane, and 2,5-divinylterephthalaldehyde is 1:0.4-1:0.2-0.5.

[0018] Preferably, in step S13, the mixture is stirred at 30-40° C. for 24-28 hours, and then stirred for 10-18 minutes. The water bath temperature is 40-65° C., and the water bath time is 12-16 hours.

[0019] Preferably, in step S14, the solvent is exchanged with anhydrous ethanol for 6 to 8 times, each time for 6 to 8 hours, and then the solvent is exchanged with n-hexane for 4 to 6 times, each time for 6 to 8 hours.

[0020] Preferably, the step S15 is drying at 40° C. and 60° C. for 24 hours respectively.

[0021] Preferably, in step S21, the mass of the Schiff base functionalized silica aerogel is 100 mg, the volume of acetonitrile is 30 mL, and stirring is performed for 24 to 28 hours.

[0022] Preferably, in step S22, the molar ratio of pyrene, functional monomer, and cross-linking agent is 1:2 to 10:8 to 24, the functional monomer is at least one of styrene, methacrylic acid, 4-vinylpyridine, and methacrylamide, the cross-linking agent is at least one of divinylbenzene and ethylene glycol diacrylate, the initiator is AIBN, AIBN is 30 mg, the water bath temperature is 65 to 70°C, and the polymerization reaction lasts for 24 to 28 hours.

[0023] Preferably, in step S23, the drying temperature is 60-70° C., and the drying time is 12-18 hours.

[0024] The second purpose of the present invention is to provide an application of a Schiff base functionalized silica aerogel / benzo(a)pyrene molecularly imprinted material, wherein the Schiff base functionalized silica aerogel / benzo(a)pyrene molecularly imprinted material is loaded into a solid phase extraction empty column, and appropriate pressure is applied to tightly pack the powder for the detection of benzo(a)pyrene.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] (1) The present invention uses DVA monomer, which is the abbreviation of 2,5-divinylterephthalaldehyde. The aldehyde group of DVA reacts with the amino group of 3-aminopropyltriethoxysilane to form a Schiff base reaction, introducing a Schiff base group to form a strong interaction with the electron-deficient region of benzo(a)pyrene. The nitrogen atom in the Schiff base group has a high electron density and can form a hydrogen bond with the hydrogen donor in the benzo(a)pyrene molecule. The aromatic ring structure of the Schiff base can generate a π-π interaction with the benzo(a)pyrene molecule, thereby significantly improving the adsorption capacity of the material.

[0027] (2) The present invention uses Schiff base functionalized silica aerogel as the substrate. Its porous structure and high porosity provide a large number of adsorption sites and an expanded specific surface area, allowing the material to accommodate more benzo(a)pyrene molecules, further improving the adsorption efficiency.

[0028] (3) The present invention utilizes the double bond functional group of DVA and introduces double bonds to further prepare molecularly imprinted polymers. The dual functions of Schiff base functionalization and molecular imprinting give the material stronger chemical reactivity, and provide a highly matched pore structure for benzo(a)pyrene through molecular imprinting technology, forming a dual recognition function. Pores that highly match the molecular structure and functional groups of benzo(a)pyrene are formed on the surface of the Schiff base functionalized silica aerogel, thereby giving the material a high selectivity for benzo(a)pyrene. This method not only enables the material to effectively remove benzo(a)pyrene, but also suppresses the interference of other similar molecules, thereby improving adsorption selectivity and sensitivity.

[0029] (4) Pyrene, a structural analogue of benzo(a)pyrene, has a similar aromatic ring structure, but its molecular size and chemical properties are relatively mild. The present invention uses pyrene as a virtual template, avoiding the direct use of benzo(a)pyrene, a highly toxic substance, in the preparation process, reducing operational safety risks and environmental pollution. Compared with traditional technologies, the template molecule selection of the present invention is more environmentally friendly and less costly, which is conducive to large-scale industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a flow chart for preparing the Schiff base functionalized silica aerogel / benzo(a)pyrene molecularly imprinted material of the present invention;

[0031] Figure 2 This is a scanning electron microscope image of the Schiff base functionalized silica aerogel / benzo(a)pyrene molecular imprinted material of the present invention. DETAILED DESCRIPTION

[0032] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0033] Example 1

[0034] like Figures 1 to 2As shown, 3-aminopropyltriethoxysilane (APTES) was dissolved in 15 mL of ethanol, and 2,5-divinylterephthalaldehyde (DVA) dissolved in 15 mL of ethanol was slowly added. The mixture was stirred at 30°C for 6 hours to obtain Solution A. 10 mL of tetraethyl orthosilicate (TEOS) was dissolved in a mixture of 26 mL of ethanol and 12 mL of 0.1 mol / L HCl and stirred at 60°C for 2 hours to obtain Solution B. Solution A was slowly added to Solution B, and the mixture was stirred at 30°C for 24 hours. Then, 4 mL of 1 mol / L ammonia was added to adjust the pH to 7. After stirring for 10 minutes, the mixture was placed in a 40°C water bath for 12 hours to form a gel. Six solvent exchanges were performed with anhydrous ethanol, each for 6 hours, followed by four solvent exchanges with n-hexane, each for 6 hours. The solvent-exchanged sample was placed in a vacuum drying oven and dried at 40°C and then 60°C for 24 hours to obtain a Schiff base-functionalized silica aerogel.

[0035] Pyrene was dissolved in acetonitrile, and 100 mg of Schiff base-functionalized silica aerogel was added. The mixture was stirred for 24 hours to allow prepolymerization of the pyrene with the Schiff base groups. To the prepolymerized solution, 0.8 mmol of the functional monomer styrene, 4 mmol of the crosslinker divinylbenzene, and 10 mg of the initiator AIBN were added. Free radical polymerization was carried out in a 65°C water bath under nitrogen for 24 hours. After the reaction, the product was centrifuged and washed twice with 40 mL of acetonitrile each time. The product was then eluted with dichloromethane to remove the template molecules. The product was then vacuum dried at 60°C for 12 hours to obtain the Schiff base-functionalized silica aerogel / benzo(a)pyrene molecularly imprinted material.

[0036] Example 2

[0037] Pyrene was dissolved in acetonitrile, and 100 mg of Schiff base-functionalized silica aerogel was added. The mixture was stirred for 24 hours to allow prepolymerization of the pyrene with the Schiff base groups. To this prepolymerization solution, 0.8 mmol of the functional monomer methacrylic acid, 4 mmol of the crosslinker divinylbenzene, and 10 mg of the initiator AIBN were added. Free radical polymerization was carried out in a 65°C water bath under nitrogen for 24 hours. After the reaction, the product was centrifuged and washed twice with 40 mL of acetonitrile each time. The product was then eluted with dichloromethane to remove the template molecules. The product was then vacuum dried at 60°C for 12 hours to obtain the Schiff base-functionalized silica aerogel / benzo(a)pyrene molecularly imprinted material.

[0038] Example 3

[0039] Pyrene was dissolved in acetonitrile, and 100 mg of Schiff base-functionalized silica aerogel was added. The mixture was stirred for 24 hours to allow prepolymerization of the pyrene with the Schiff base groups. To the prepolymerized solution, 0.8 mmol of the functional monomer 4-vinylpyridine, 4 mmol of the crosslinker divinylbenzene, and 10 mg of the initiator AIBN were added. Free radical polymerization was carried out in a 65°C water bath under nitrogen for 24 hours. After the reaction, the product was centrifuged and washed twice with 40 mL of acetonitrile each time. The product was then eluted with dichloromethane to remove the template molecules. The product was then vacuum dried at 60°C for 12 hours to obtain the Schiff base-functionalized silica aerogel / benzo(a)pyrene molecularly imprinted material.

[0040] Example 4

[0041] Pyrene was dissolved in acetonitrile, and 100 mg of Schiff base-functionalized silica aerogel was added. The mixture was stirred for 24 hours to allow prepolymerization of the pyrene with the Schiff base groups. To this prepolymerization solution, 0.8 mmol of the functional monomer methacrylamide, 4 mmol of the crosslinker divinylbenzene, and 10 mg of the initiator AIBN were added. Free radical polymerization was carried out in a 65°C water bath under nitrogen protection for 24 hours. After the reaction, the resulting product was centrifuged and washed twice with 40 mL of acetonitrile each time. The product was then eluted with dichloromethane to remove the template molecules. The product was then vacuum dried at 60°C for 12 hours to obtain the Schiff base-functionalized silica aerogel / benzo(a)pyrene molecularly imprinted material.

[0042] Test Example 1

[0043] The Schiff base functionalized silica material aerogel / benzo(a)pyrene molecular imprinting material prepared in Examples 1-4 and the purchased commercial filler 1 (benzo(a)pyrene molecular imprinting column of Polykai Science and Technology, product number JK-BBZ500) were tested for specific surface area and pore volume (the results are shown in Table 1). The specific surface area refers to the total area per unit mass of filler, and the pore volume refers to the pore volume per unit mass of adsorbent. When other parameters remain unchanged, the larger the specific surface area and pore volume, the stronger the adsorption performance of the filler.

[0044] Table 1: Specific surface area and pore volume of Schiff base functionalized silica aerogel / benzo(a)pyrene molecularly imprinted material.

[0045] sample <![CDATA[Specific surface area (m 2 / g)]]> <![CDATA[Pore volume (m 3 / g)]]> Example 1 156.2 0.288 Example 2 333.7 0.302 Example 3 186.4 0.277 Example 4 341.5 0.320 Commercial filler 1 162.0 0.235

[0046] Test Example 2

[0047] The Schiff base functionalized silica aerogel / benzo(a)pyrene molecularly imprinted material prepared in Example 1-4 was loaded into a column. The solid phase extraction column had a capacity of 6 mL, and each column was loaded with 500 mg of filler. The commercial filler 1 (benzo(a)pyrene molecularly imprinted column from Jukai Kechuang, item number JK-BBZ500) was used to perform a solid phase extraction experiment of benzo(a)pyrene from soybean oil (the results are shown in Table 2). The specific steps are as follows:

[0048] Weigh 0.4 g of edible vegetable oil into a 10 mL centrifuge tube, add 5 mL of n-hexane, vortex mix for 1 minute, and wait for purification.

[0049] The specific steps of the solid phase extraction experiment are as follows:

[0050] (1) Activation balance: 5 mL dichloromethane, 5 mL n-hexane

[0051] (2) Sample loading: 5 mL of sample solution to be purified

[0052] (3) Eluent: 6 mL of n-hexane

[0053] (4) Elution: 6 mL of dichloromethane, collect

[0054] (5) Volume adjustment: The eluate was blown to dryness with nitrogen at 40°C, reconstituted with 0.4 mL of acetonitrile, sonicated for 1 minute, vortex mixed for 1 minute, and filtered through a 0.22 μm organic syringe filter before HPLC detection.

[0055] Table 2: Recovery of benzo(a)pyrene by molecularly imprinted packing.

[0056] sample Spike concentration (ng / g) Benzo(a)pyrene recovery rate (%) Example 1 10 73.6 Example 2 10 93.1 Example 3 10 84.7 Example 4 10 98.4 Commercial filler 1 10 85.6

[0057] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A Schiff base functionalized silica aerogel / benzo(a)pyrene molecularly imprinted material, characterized in that: The imprinting material is prepared by the following steps: S1. Preparation of Schiff base functionalized silica aerogel: S11, dissolving 3-aminopropyltriethoxysilane in ethanol, then slowly adding 2,5-divinylterephthalaldehyde dissolved in ethanol, stirring to react, to obtain solution A; S12, dissolving tetraethyl orthosilicate in a mixed solution of ethanol and 0.1 mol / L HCl, stirring to react, to obtain solution B; S13, slowly adding the solution A obtained in step S11 to the solution B obtained in step S12, stirring for reaction, adding 1 mol / L ammonia water to adjust the pH to 7, continuing stirring, and forming a gel in a water bath; S14, performing a solvent exchange with anhydrous ethanol, and then performing a solvent exchange with n-hexane; S15, placing the solvent-exchanged sample in a vacuum drying oven to dry, thereby obtaining a Schiff base-functionalized silica aerogel; S2. Preparation of Schiff base functionalized silica aerogel / benzo(a)pyrene molecularly imprinted material: S21, dissolving pyrene in acetonitrile, adding Schiff base functionalized silica aerogel, stirring to react, so that pyrene and Schiff base groups are prepolymerized; S22, adding functional monomers, crosslinking agents and initiators to the prepolymer solution of step S21, and performing free radical polymerization in a water bath under nitrogen protection; S23, centrifuging the product obtained after the reaction in step S22, washing with acetonitrile; eluting the product with dichloromethane to remove the template molecules; and vacuum drying the product to obtain a Schiff base functionalized silica aerogel / benzo(a)pyrene molecularly imprinted material.

2. The Schiff base functionalized silica aerogel / benzo(a)pyrene molecularly imprinted material according to claim 1, characterized in that: The step S11 is stirred at 30-35° C. for 6-8 hours, and the step S12 is stirred at 60-65° C. for 2-4 hours. The mass ratio of tetraethyl orthosilicate, 3-aminopropyltriethoxysilane, and 2,5-divinylterephthalaldehyde is 1:0.4-1:0.2-0.

5.

3. The Schiff base functionalized silica aerogel / benzo(a)pyrene molecularly imprinted material according to claim 1, wherein: In step S13, the mixture is stirred at 30-40° C. for 24-28 hours, and then stirred for 10-18 minutes. The water bath temperature is 40-65° C., and the water bath time is 12-16 hours.

4. The Schiff base functionalized silica aerogel / benzo(a)pyrene molecularly imprinted material according to claim 1, wherein: In step S14, the solvent is exchanged with anhydrous ethanol for 6 to 8 times, each time for 6 to 8 hours, and then the solvent is exchanged with n-hexane for 4 to 6 times, each time for 6 to 8 hours.

5. The Schiff base functionalized silica aerogel / benzo(a)pyrene molecularly imprinted material according to claim 1, wherein: The step S15 is to dry at 40° C. and 60° C. for 24 hours respectively.

6. The Schiff base functionalized silica aerogel / benzo(a)pyrene molecularly imprinted material according to claim 1, wherein: In step S21, the mass of the Schiff base functionalized silica aerogel is 100 mg, the volume of acetonitrile is 30 mL, and stirring is performed for 24 to 28 hours.

7. The Schiff base functionalized silica aerogel / benzo(a)pyrene molecularly imprinted material according to claim 1, wherein: In step S22, the molar ratio of pyrene, functional monomer, and cross-linking agent is 1:2 to 10:8 to 24, the functional monomer is at least one of styrene, methacrylic acid, 4-vinylpyridine, and methacrylamide, the cross-linking agent is at least one of divinylbenzene and ethylene glycol diacrylate, the initiator is AIBN, the amount of AIBN is 30 mg, the water bath temperature is 65 to 70° C., and the polymerization reaction lasts for 24 to 28 hours.

8. The Schiff base functionalized silica aerogel / benzo(a)pyrene molecularly imprinted material according to claim 1, wherein: In step S23, the drying temperature is 60-70° C., and the drying time is 12-18 hours.

9. A use of the Schiff base functionalized silica aerogel / benzo(a)pyrene molecularly imprinted material according to any one of claims 1 to 8, characterized in that: The Schiff base functionalized silica aerogel / benzo(a)pyrene molecularly imprinted material was loaded into a solid phase extraction empty column, and appropriate pressure was applied to tightly pack the powder for the detection of benzo(a)pyrene.

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