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

Abstract

The invention discloses a Schiff base functionalized silica aerogel / benzo (a) pyrene molecularly imprinted material and application thereof, pyrene is used as a virtual template molecule, and Schiff base functionalized silica aerogel is added; adding a functional monomer, a cross-linking agent and an initiator; and preparing the Schiff base functionalized silicon dioxide aerogel / benzo (a) pyrene molecularly imprinted material by adopting a surface imprinting polymerization method. The silicon dioxide aerogel is used as a base material, and the adsorption efficiency of benzo (a) pyrene is enhanced through the porous structure and high porosity of the silicon dioxide aerogel. Schiff base groups are introduced to form strong interaction with benzo (a) pyrene molecules, so that the adsorption capacity is further improved. And by combining a molecular imprinting technology, holes highly matched with benzo (a) pyrene are formed on the surface of the Schiff base functionalized aerogel, so that the material is endowed with high selectivity. Pyrene is used as a virtual template, so that the use of benzo (a) pyrene is avoided, and the environmental risk and the material cost are reduced.

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 compound and is widely considered to be one of the strongest carcinogens in the world. Benzo(a)pyrene is mainly produced during high-temperature baking, smoking, leaching and pressing, which can cause thermal cracking, cyclization and polymerization of fats, cholesterol, proteins and carbohydrates. After ingestion by the human body, it can cause lung cancer, liver cancer, gastrointestinal cancer, etc. In order to ensure food safety, my country's "National Food Safety Standard Limits of Contaminants in Food" (GB2762-2017) stipulates that the limit of benzo(a)pyrene in vegetable oil is 10μg / kg. However, the processing of many vegetable oils, such as the pressing method of sesame oil, linseed oil and rapeseed oil, requires high-temperature frying of seeds. If the temperature is not properly controlled, it is easy to cause the benzo(a)pyrene content to exceed the national standard. This further highlights the importance of detecting benzo(a)pyrene in vegetable oils.

[0003] The solid phase extraction column used in traditional detection technology has poor selectivity and is difficult to meet the detection requirements of trace targets in complex matrices. Therefore, a Schiff base functionalized silica aerogel / benzo(a)pyrene molecular imprinting material and its application are urgently needed. Summary of the invention

[0004] In order to solve the defects of the prior art, the present invention provides a Schiff base functionalized silica aerogel / benzo(a)pyrene molecular imprinting material and its application, which combines the chemical activity of the Schiff base group, the high specific surface area and porous structure of the silica aerogel, and the selective imprinting ability of the molecular imprinting technology to form a multifunctional new adsorption material with the advantages of convenient operation, low reagent consumption, high purification effect, few interfering chromatographic peaks, etc., and is suitable for the processing of 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 molecular 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 solvent exchange using anhydrous ethanol, and then performing solvent exchange using 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 molecular imprinting 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; then eluting the product with dichloromethane to remove the template molecules; and vacuum drying the product to obtain Schiff base functionalized silica aerogel / benzo(a)pyrene molecular imprinting 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, stirring is first maintained at 30-40° C. for 24-28 hours, stirring is continued 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 performed by 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 1:2-10:8-24, 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 65-70°C, and the polymerization reaction lasts for 24-28 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 Schiff base functionalized silica aerogel / benzo(a)pyrene molecular imprinting material, which is used to detect benzo(a)pyrene by loading the Schiff base functionalized silica aerogel / benzo(a)pyrene molecular imprinting material into a solid phase extraction empty column and applying appropriate pressure to tightly fill the powder.

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

[0026] (1) The present invention uses DVA monomer, DVA is the abbreviation of 2,5-Divinylterephthalaldehyde, and utilizes the aldehyde group of DVA to react with the amino group of 3-aminopropyltriethoxysilane to introduce the 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, which can form a hydrogen bond with the hydrogen donor in the benzo(a)pyrene molecule. The aromatic ring structure of the Schiff base can produce 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, so that the material can accommodate more benzo(a)pyrene molecules, further improving the adsorption efficiency.

[0028] (3) The present invention utilizes the double bond functional group of DVA, introduces double bonds and further prepares molecular imprinting 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. Holes that highly match the molecular structure and functional groups of benzo(a)pyrene are formed on the surface of 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 benzopyrene, but also suppresses the interference of other similar molecules, thereby improving adsorption selectivity and sensitivity.

[0029] (4) Pyrene, as 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 the safety risks and environmental pollution of the operation. Compared with traditional technologies, the template molecule selection of the present invention is more environmentally friendly and has lower costs, which is conducive to large-scale industrial applications. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0032] The preferred embodiments of the present invention are described below in conjunction with 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 Figure 1 to Figure 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, and the mixture was stirred at 30 ° C for 6 hours to obtain solution A. 10 mL of tetraethyl orthosilicate (TEOS) was dissolved in a mixed solution 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 stirred at 30 ° C for 24 hours, and then 4 mL of 1 mol / L ammonia water was added to adjust the pH to 7. After stirring for 10 minutes, it was placed in a 40 ° C water bath for 12 hours to form a gel. Solvent exchange was performed 6 times with anhydrous ethanol, each time for 6 hours, and then solvent exchange was performed 4 times with n-hexane, each time for 6 hours. The sample after solvent exchange was placed in a vacuum drying oven and dried at 40 ° C and 60 ° C for 24 hours respectively to obtain Schiff base functionalized silica aerogel.

[0035] Dissolve pyrene in acetonitrile, add 100 mg of Schiff base functionalized silica aerogel, and stir for 24 hours to prepolymerize pyrene with Schiff base groups. Add 0.8 mmol of functional monomer styrene, 4 mmol of crosslinker divinylbenzene and 10 mg of initiator AIBN to the prepolymerization solution, and carry out free radical polymerization in a 65°C water bath under nitrogen protection for 24 hours. After the reaction, the product is centrifuged and washed twice with acetonitrile, each time with 40 mL of acetonitrile. Then elute the product with dichloromethane to remove the template molecule. The product is vacuum dried at 60°C for 12 hours to obtain Schiff base functionalized silica aerogel / benzo(a)pyrene molecular imprinting material.

[0036] Example 2

[0037] Dissolve pyrene in acetonitrile, add 100 mg of Schiff base functionalized silica aerogel, and stir for 24 hours to prepolymerize pyrene with Schiff base groups. Add 0.8 mmol of functional monomer methacrylic acid, 4 mmol of crosslinker divinylbenzene and 10 mg of initiator AIBN to the prepolymerization solution, and carry out free radical polymerization in a 65°C water bath under nitrogen protection for 24 hours. After the reaction, the product is centrifuged and washed twice with acetonitrile, each time with 40 mL of acetonitrile. Then elute the product with dichloromethane to remove the template molecule. The product is vacuum dried at 60°C for 12 hours to obtain Schiff base functionalized silica aerogel / benzo(a)pyrene molecular imprinting material.

[0038] Example 3

[0039] Dissolve pyrene in acetonitrile, add 100 mg of Schiff base functionalized silica aerogel, and stir for 24 hours to prepolymerize pyrene with Schiff base groups. Add 0.8 mmol of functional monomer 4-vinylpyridine, 4 mmol of crosslinker divinylbenzene and 10 mg of initiator AIBN to the prepolymerization solution, and carry out free radical polymerization in a 65°C water bath under nitrogen protection for 24 hours. After the reaction, the product is centrifuged and washed twice with acetonitrile, each time with 40 mL of acetonitrile. Then elute the product with dichloromethane to remove the template molecule. The product is vacuum dried at 60°C for 12 hours to obtain Schiff base functionalized silica aerogel / benzo(a)pyrene molecular imprinting material.

[0040] Example 4

[0041] Dissolve pyrene in acetonitrile, add 100 mg of Schiff base functionalized silica aerogel, and stir for 24 hours to prepolymerize pyrene with Schiff base groups. Add 0.8 mmol of functional monomer methacrylamide, 4 mmol of crosslinker divinylbenzene and 10 mg of initiator AIBN to the prepolymerization solution, and carry out free radical polymerization in a 65°C water bath under nitrogen protection for 24 hours. After the reaction, the product is centrifuged and washed twice with acetonitrile, each time with 40 mL of acetonitrile. Then elute the product with dichloromethane to remove the template molecule. The product is vacuum dried at 60°C for 12 hours to obtain Schiff base functionalized silica aerogel / benzo(a)pyrene molecular imprinting 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 (benzopyrene molecular imprinting column of Polykai Science and Technology, item 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 molecular imprinting 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 material aerogel / benzo(a)pyrene molecular imprinting material prepared in Example 1-4 was loaded into a column, the solid phase extraction column capacity was 6 mL, each column was loaded with 500 mg of filler, and the purchased commercial filler 1 (benzo(a)pyrene molecular imprinting column of Jukai Kechuang, item number JK-BBZ500) was used for solid phase extraction experiment of benzo(a)pyrene in soybean oil (the results are shown in Table 2), and the specific operation 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 min, vortex mixed for 1 min, and filtered through a 0.22 μm organic syringe filter for HPLC detection.

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

[0056] sample Spiked 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 description is only a preferred embodiment of the present invention and is 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 can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A Schiff base functionalized silica aerogel / benzo(a)pyrene molecular imprinting 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 solvent exchange using anhydrous ethanol, and then performing solvent exchange using 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 molecular imprinting 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; then eluting the product with dichloromethane to remove the template molecules; and vacuum drying the product to obtain Schiff base functionalized silica aerogel / benzo(a)pyrene molecular imprinting material.

2. The Schiff base functionalized silica aerogel / benzo(a)pyrene molecular imprinting 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 molecular imprinting material according to claim 1, characterized in that: In the step S13, the temperature is maintained at 30-40° C. and stirred for 24-28 hours, and the stirring time is continued 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 molecular imprinting material according to claim 1, characterized in that: 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 molecular imprinting material according to claim 1, characterized in that: 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 molecular imprinting material according to claim 1, characterized in that: In the 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 molecular imprinting material according to claim 1, characterized in that: In the step S22, the molar ratio of pyrene, functional monomer and cross-linking agent is 1:2-10:8-24, 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 65-70°C, and the polymerization reaction lasts for 24-28 hours.

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

9. An application of the Schiff base functionalized silica aerogel / benzo(a)pyrene molecular imprinting material as claimed in any one of claims 1 to 8, characterized in that: The Schiff base functionalized silica aerogel / benzo(a)pyrene molecular imprinting material was loaded into a solid phase extraction empty column, and appropriate pressure was applied to make the powder densely packed for the detection of benzo(a)pyrene.

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