Preparation of COFs doped high internal phase emulsion based porous carbon material and application thereof

Abstract

The application discloses a preparation of COFs doped high internal phase emulsion based porous carbon material and application thereof, and relates to the field of adsorbing material preparation and sample pretreatment technology. The high internal phase emulsion of styrene and divinylbenzene stabilized by a covalent organic framework and Span80 is used to prepare amphiphilic polyHIPEs-COFs material with crosslinked intercommunication and porous network structure. The rigidity of the high internal phase emulsion polymer of the styrene and divinylbenzene based polyHIPEs material is improved by doping COFs, so that the material is not easy to collapse, the hydrophobic property of the material is improved, the adsorbing capacity of the material in water is enhanced, the material has hydrophilic and lipophilic amphiphilicity, the material has good adsorbing performance for biamide insecticides, the material preparation process is simple, the material has good repeatability, and the desorption efficiency of the material for target objects is still above 94% when the material is reused for more than 10 times.

Description

Technical Field

[0001] This invention relates to the field of adsorption material preparation and sample pretreatment technology, specifically to the preparation and application of a COFs-doped high internal phase emulsion-based porous carbon material. Background Technology

[0002] Vegetables are crucial for human nutrition and disease prevention, providing essential nutrients and offering health benefits. However, due to factors such as crop pests, weeds, and diseases, approximately 30% of potential crop yields are lost annually. Diamide pesticides are widely used insecticides that act on the nervous systems of various insects, effectively controlling pest populations. However, excessive use of pesticides leads to pollution of vegetables, water sources, and soil, causing harm to the environment and humans. Therefore, efficient and rapid detection of diamide pesticide content in vegetables is particularly important.

[0003] Because the concentration of diamide pesticides in complex food matrices is low, direct detection of diamide pesticides in vegetables is difficult. Therefore, pretreatment of vegetable samples is necessary to eliminate as much interference as possible before stable determination of diamide pesticides. Solid-phase extraction (SPE) has become the most traditional and widely used sample pretreatment technique due to its advantages such as simple operation, low reagent consumption, low cost, and small analytical error. Currently, various SPE adsorbents have been used for the separation and detection of pesticides, such as multi-walled carbon nanotubes, metal-organic frameworks (MOFs), and C-18 adsorbents. However, research on the adsorption of diamide pesticides is limited, and new methods for the separation and detection of diamide pesticides still need to be developed.

[0004] PolyHIPEs are porous emulsion template polymers synthesized in high internal phase emulsions (HIPEs). HIPEs are high-viscosity paste-like emulsions in which the internal phase (usually defined as occupying more than 74% of the volume) is dispersed in a continuous external phase. Due to their cross-linked, interconnected, layered, and porous structure, they have wide applications in chemical measurement, such as adsorbent materials, catalysts, gas storage, and sensors. PolyHIPEs are generally obtained through free radical thermal polymerization. Although they possess the characteristic of a layered porous network structure, they also suffer from insufficient rigidity, easy material collapse, strong hydrophobicity and oleophilicity, and weakened adsorption performance in environmental water samples. Therefore, improving the hydrophobicity of the material is a major challenge for polyHIPEs. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing and applying a COFs-doped high internal phase emulsion-based porous carbon material. By doping with COFs to modify polyHIPEs, its rigidity is enhanced, making the material less prone to collapse, and its hydrophobic properties are improved, thereby enhancing its adsorption capacity in water. This material is then used as an adsorbent material for solid-phase extraction in the adsorption-separation analysis of pesticides in complex vegetable samples.

[0006] To achieve the above objectives, this invention provides a method for preparing COFs-doped high internal phase emulsion-based porous carbon materials, comprising the following steps:

[0007] S1. Preparation of spherical flower-like COFs materials;

[0008] S2. Dispersion and modification of COFs in aqueous phase;

[0009] PVP was added to water and ultrasonically treated, and then spherical flower cluster COFs material was added and stirred to form a uniformly dispersed aqueous phase.

[0010] Preparation of S3 and polyHIPEs-COFs;

[0011] The oil phase containing Span80, DVB, STY and AIBN was mixed and stirred with the aqueous phase containing PVP-COFs to form a uniform high internal phase emulsion. Then, a thermal polymerization reaction was carried out at 65°C. The reaction residues were removed by washing with water and ethanol, and the polyHIPEs-COFs were obtained by freeze drying.

[0012] Preferably, the specific preparation steps of step S1 are as follows:

[0013] (1) Weigh 17.8 mg of 4,4′,4′-(1,3,5-triazine-2,4,6-triyl)triphenylamine (TAPT) and 15.5 mg of 2,3,5,6-tetrafluoroterephthalaldehyde (TFA) and place them in a centrifuge tube. Add 2.20 mL of dioxane and 2.80 mL of mesitylene mixed organic solvent and sonicate for 5 min to ensure thorough dispersion.

[0014] (2) Add 0.4 mL of 12 M HAc, shake in a vortex mixer for 30 s, and let stand at room temperature for 24 h to obtain a yellow turbid liquid.

[0015] (3) Centrifuge, collect the yellow solid and wash it with THF, acetonitrile and ethanol in sequence.

[0016] (4) The washed solid was placed in an oven and vacuum dried at 60°C for 24 hours to obtain spherical flower cluster COFs material.

[0017] Preferably, in step S2, the mass of PVP used is 13.4g, the mass of COFs material is 0.6g, and the volume of water is 100mL.

[0018] Preferably, the oil phase in step S3 contains 150 μL of Span80, 250 μL of DVB, 500 μL of STY, and 20 mg of AIBN.

[0019] Preferably, the internal phase ratio of the high internal phase emulsion in step S3 is 83%.

[0020] Preferably, the freeze-drying conditions in step S3 are -30°C for 24 hours.

[0021] The present invention also provides a COFs-doped high internal phase emulsion-based porous carbon material prepared by the above preparation method.

[0022] Preferably, the COFs doping amount in the porous carbon material prepared by the above method is 0.9-2.1%.

[0023] This invention also provides the application of the above-mentioned porous carbon material in the adsorption, separation and detection of diamide insecticides in vegetables.

[0024] Preferably, the application of the porous carbon material in the adsorption, separation, and detection of diamide pesticides in vegetables specifically includes the following steps:

[0025] (1) Prepare a standard solution of diamide insecticide;

[0026] (2) Grind polyHIPEs-COFs material into fine powder, fill it evenly into a solid phase extraction column, and then activate the filled polyHIPEs-COFs solid phase extraction column with methanol and water in sequence.

[0027] (3) The insecticide standard solution is transported through a solid phase extraction column. After adsorption is complete, the residual liquid is collected, filtered, and the concentration of the insecticide is detected by high performance liquid chromatography.

[0028] (4) The adsorbed material was desorbed by using 1 mL of methanol / water to remove the pesticide. The desorbed liquid was collected and analyzed by high performance liquid chromatography.

[0029] Therefore, this invention provides a method for preparing and applying COFs-doped high internal phase emulsion-based porous carbon materials, with the following specific beneficial effects:

[0030] (1) The present invention prepares an amphiphilic polyHIPEs-COFs material with a cross-linked, porous network structure by using a styrene and divinylbenzene high internal phase emulsion stabilized by a covalent organic framework and Span80. The preparation process of this material is simple and reproducible. The rigidity and hydrophobicity of the high internal phase emulsion polymer of styrene and divinylbenzene polyHIPEs material are improved by the doping of COFs, so that it has the amphiphilic properties of hydrophilic and lipophilic.

[0031] (2) The porous polymer polyHIPEs-COFs prepared in this invention is used as an adsorption material for solid phase extraction and applied to the adsorption and separation analysis of pesticides in complex vegetable samples. It has good adsorption performance for diamide pesticides.

[0032] (3) The method of the present invention has the advantages of simple operation and easy control of reaction conditions.

[0033] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0034] Figure 1 This is a schematic diagram illustrating the process of preparing porous carbon materials and their application in accordance with the present invention;

[0035] Figure 2 These are scanning electron micrographs of the materials prepared in Examples 1-5 and Comparative Examples 1-7 of the present invention, wherein DH corresponds to Examples 1-5 respectively; AC and IL correspond to Comparative Examples 1-7 respectively.

[0036] Figure 3 The images shown are scanning electron microscope (SEM) images of spherical flower cluster COFs, polyHIPEs, and polyHIPEs-COFs obtained in Example 5 of this invention. In the images, A represents spherical flower cluster COFs; B represents polyHIPEs; and C represents polyHIPEs-COFs.

[0037] Figure 4 Comparison of FT-IR curves of spherical flower cluster COFs, polyHIPEs, and polyHIPEs-COFs obtained in Example 5 of the present invention.

[0038] Figure 5 Thermogravimetric analysis curve of polyHIPEs-COFs obtained in Example 5 of this invention;

[0039] Figure 6This is a comparative diagram of the hydrophilicity and lipophilicity of the spherical flower cluster COFs, polyHIPEs, and polyHIPEs-COFs prepared in Example 5 of the present invention. In the diagram, A represents spherical flower cluster COFs; B represents polyHIPEs; and C represents polyHIPEs-COFs.

[0040] Figure 7 This is an adsorption capacity curve of the polyHIPEs-COFs material prepared in Example 5 of the present invention for two diamide insecticides.

[0041] Figure 8 This is a comparison chart of the adsorption efficiency of the polyHIPEs-COFs material prepared in Example 5 of the present invention for diamide insecticides and other types of insecticides.

[0042] Figure 9 This is a graph showing the reusability evaluation of the polyHIPEs-COFs material prepared in Example 5 of the present invention.

[0043] Figure 10 This is the adsorption-desorption chromatogram of the polyHIPEs-COFs material prepared in Example 5 of this invention on actual vegetable samples, where i: untreated vegetable sample stock solution; ii: unspecified vegetable sample eluent after SPE treatment; iii: untreated sample spiked with 500 μg / L mixed standard solution; iv: spiked vegetable sample eluent after SPE treatment. a: bromocyanamide, b: chlorantraniliprole. Detailed Implementation

[0044] This invention provides a method for preparing COFs-doped high internal phase emulsion-based porous carbon materials, comprising the following steps:

[0045] S1. Preparation of spherical flower-like COFs materials;

[0046] (1) Weigh 17.8 mg of 4,4′,4′-(1,3,5-triazine-2,4,6-triyl)triphenylamine (TAPT) and 15.5 mg of 2,3,5,6-tetrafluoroterephthalaldehyde (TFA) and place them in a centrifuge tube. Add 2.20 mL of dioxane and 2.80 mL of mesitylene mixed organic solvent and sonicate for 5 min to ensure thorough dispersion.

[0047] (2) Add 0.4 mL of 12 M HAc, shake in a vortex mixer for 30 s, and let stand at room temperature for 24 h to obtain a yellow turbid liquid.

[0048] (3) Centrifuge, collect the yellow solid and wash it with THF, acetonitrile and ethanol in sequence.

[0049] (4) The washed solid was placed in an oven and vacuum dried at 60°C for 24 hours to obtain spherical flower cluster COFs material.

[0050] S2. Dispersion and modification of COFs in aqueous phase;

[0051] 13.4 g of PVP was added dropwise to 100 mL of water and sonicated for 30 min to dissolve completely. Then, 0.6 g of COFs was slowly added while stirring, and magnetic stirring was performed for 24 hours to form a uniformly dispersed aqueous phase.

[0052] Globular flower clusters of COFs have a certain degree of hydrophilicity, but they are not easy to disperse and stabilize uniformly in the aqueous phase. This phenomenon can be improved by adding PVP to the aqueous phase.

[0053] Preparation of S3 and polyHIPEs-COFs;

[0054] An oil phase containing 150 μL of Span80, 250 μL of DVB, 500 μL of STY, and 20 mg of AIBN was mixed with an aqueous dispersion containing PVP-COFs and stirred for 30 minutes. Then, the mixture was stirred at 3000 rpm using a homogenizer to form a homogeneous high internal phase emulsion (internal phase ratio of 83%). The emulsion was then thermally polymerized at 65 °C for 18 to 24 hours. The synthesized polymer was repeatedly washed with water and ethanol to remove reaction residues, and then freeze-dried at -30 °C for 24 hours to obtain polyHIPEs-COFs.

[0055] In the porous carbon material prepared by the above method, the COFs doping amount is 0.9-2.1%.

[0056] This invention also provides the application of the above-mentioned porous carbon material in the adsorption, separation, and detection of diamide insecticides in vegetables, specifically including the following steps:

[0057] (1) Prepare a standard solution of diamide insecticide;

[0058] (2) Grind polyHIPEs-COFs material into fine powder, fill it evenly into a solid phase extraction column, and then activate the filled polyHIPEs-COFs solid phase extraction column with methanol and water in sequence.

[0059] (3) The insecticide standard solution is transported through a solid phase extraction column. After adsorption is complete, the residual liquid is collected, filtered, and the concentration of the insecticide is detected by high performance liquid chromatography.

[0060] (4) The adsorbed material was desorbed by using 1 mL of methanol / water to remove the pesticide. The desorbed liquid was collected and analyzed by high performance liquid chromatography.

[0061] The process and application of preparing porous carbon materials according to this invention are as follows: Figure 1 As shown.

[0062] The following detailed description of embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0063] Example 1

[0064] This embodiment provides a method for preparing COFs-doped high internal phase emulsion-based porous carbon materials, including the following steps:

[0065] S1. Preparation of spherical flower-like COFs materials;

[0066] (1) Weigh 17.8 mg of 4,4′,4′-(1,3,5-triazine-2,4,6-triyl)triphenylamine (TAPT) and 15.5 mg of 2,3,5,6-tetrafluoroterephthalaldehyde (TFA) and place them in a centrifuge tube. Add 2.20 mL of dioxane and 2.80 mL of mesitylene mixed organic solvent and sonicate for 5 min to ensure thorough dispersion.

[0067] (2) Add 0.4 mL of 12 M HAc, shake in a vortex mixer for 30 s, and let stand at room temperature for 24 h to obtain a yellow turbid liquid.

[0068] (3) Centrifuge, collect the yellow solid and wash it with THF, acetonitrile and ethanol in sequence.

[0069] (4) The washed solid was placed in an oven and vacuum dried at 60°C for 24 hours to obtain spherical flower cluster COFs material.

[0070] S2. Dispersion and modification of COFs in aqueous phase;

[0071] 13.4 g of PVP was added dropwise to 100 mL of water and sonicated for 30 min to dissolve completely. Then, 0.6 g of COFs was slowly added while stirring, and the mixture was magnetically stirred for 24 hours to form a uniformly dispersed aqueous phase.

[0072] Preparation of S3 and polyHIPEs-COFs;

[0073] An oil phase containing 150 μL of Span80, 250 μL of DVB, 500 μL of STY, and 20 mg of AIBN was mixed with an aqueous dispersion containing PVP-COFs in a certain proportion and stirred for 30 minutes. Then, the mixture was stirred at 3000 rpm using a homogenizer to form a homogeneous high internal phase emulsion (internal phase ratio of 83%). The emulsion was then thermally polymerized at 65 °C for 18 to 24 hours. The synthesized polymer was repeatedly washed with water and ethanol to remove reaction residues, and then freeze-dried at -30 °C for 24 hours to obtain polyHIPEs-COFs.

[0074] In this embodiment, the COFs doping amount in the polyHIPEs-COFs prepared is 0.9%.

[0075] Example 2

[0076] This embodiment provides a method for preparing COFs-doped high internal phase emulsion-based porous carbon materials. The only difference from Example 1 is that the mixing ratio of the oil phase and the water phase is changed, and the COFs doping amount in the obtained polyHIPEs-COFs is 1.2%.

[0077] Example 3

[0078] This embodiment provides a method for preparing COFs-doped high internal phase emulsion-based porous carbon materials. The only difference from Example 1 is that the mixing ratio of the oil phase and the water phase is changed, and the COFs doping amount in the obtained polyHIPEs-COFs is 1.5%.

[0079] Example 4

[0080] This embodiment provides a method for preparing COFs-doped high internal phase emulsion-based porous carbon materials. The only difference from Example 1 is that the mixing ratio of the oil phase and the water phase is changed. The COFs doping amount in the obtained polyHIPEs-COFs is 1.8%.

[0081] Example 5

[0082] This embodiment provides a method for preparing COFs-doped high internal phase emulsion-based porous carbon materials. The only difference from Example 1 is that the mixing ratio of the oil phase and the water phase is changed. The COFs doping amount in the obtained polyHIPEs-COFs is 2.1%.

[0083] Comparative Example 1

[0084] This comparative example provides a method for preparing a high internal phase emulsion-based carbon material, which differs from Example 1 only in that it is not doped with COFs.

[0085] Comparative Example 2

[0086] This comparative example provides a method for preparing COFs-doped high internal phase emulsion-based carbon materials. The only difference from Example 1 is that the mixing ratio of the oil phase and the water phase is changed, and the COFs doping amount in the obtained polyHIPEs-COFs is 0.3%.

[0087] Comparative Example 3

[0088] This comparative example provides a method for preparing COFs-doped high internal phase emulsion-based carbon materials. The only difference from Example 1 is that the mixing ratio of the oil phase and the water phase is changed. The COFs doping amount in the obtained polyHIPEs-COFs is 0.6%.

[0089] Comparative Example 4

[0090] This comparative example provides a method for preparing COFs-doped high internal phase emulsion-based carbon materials. The only difference from Example 1 is that the mixing ratio of the oil phase and the water phase is changed. The COFs doping amount in the obtained polyHIPEs-COFs is 2.4%.

[0091] Comparative Example 5

[0092] This comparative example provides a method for preparing COFs-doped high internal phase emulsion-based carbon materials. The only difference from Example 1 is that the mixing ratio of the oil phase and the water phase is changed. The COFs doping amount in the obtained polyHIPEs-COFs is 2.7%.

[0093] Comparative Example 6

[0094] This comparative example provides a method for preparing COFs-doped high internal phase emulsion-based carbon materials. The only difference from Example 1 is that the mixing ratio of the oil phase and the water phase is changed. The COFs doping amount in the obtained polyHIPEs-COFs is 3.0%.

[0095] Comparative Example 7

[0096] This comparative example provides a method for preparing COFs-doped high internal phase emulsion-based carbon materials. The only difference from Example 1 is that the mixing ratio of the oil phase and the water phase is changed. The COFs doping amount in the obtained polyHIPEs-COFs is 3.2%.

[0097] The materials prepared in Examples 1-5 and Comparative Examples 1-7 were analyzed and tested using a scanning electron microscope, and the surface morphology images obtained are shown below. Figure 2 As shown, by Figure 2It is known that the doping amount of COFs affects the pore structure of polyHIPEs-COFs materials. When the doping amount is in the range of 0~2.1%, as the COF content increases, polyHIPEs-COFs gradually form a cross-linked and interconnected porous network structure (AH). Among them, when the doping amount is 0.9-2.1%, the prepared polyHIPEs-COFs obviously have a cross-linked and interconnected porous network structure (DH). When the doping amount is 2.4~3.2%, further increases in COFs will cause the porous network structure of polyHIPEs-COFs to collapse (IL).

[0098] To ensure the controllable synthesis and practical application of the material, the performance of the polyHIPEs-COFs material with a COFs doping content of 2.1% prepared in Example 5 of this application was tested.

[0099] 1. The elemental content of spherical flower cluster COFs, polyHIPEs, and polyHIPEs-COFs was analyzed and compared using scanning electron microscopy and energy dispersive spectroscopy (EDS). The results are as follows: Figure 3 As shown in the figure, COFs mainly contain four elements: C, N, O, and F; polyHIPEs mainly contain three elements: C, N, and O; and polyHIPEs-COFs mainly contain four elements: C, N, O, and F. The C, N, and O in polyHIPEs-COFs mainly come from the STY-DVB system in the oil phase and COFs and PVP in the aqueous phase, while the F element mainly comes from COFs. After doping, the F element content in the high internal phase emulsion polymer increased from none to 1.02%, and the O element content exceeded that of the undoped polymer material and COFs. This indicates that PVP successfully modified the COFs, and the modified COFs were successfully incorporated into the high internal phase emulsion polymer.

[0100] The elemental contents of spherical flower cluster COFs, polyHIPEs, and polyHIPEs-COFs are shown in Table 1.

[0101] Table 1

[0102]

[0103] 2. A comprehensive comparison of the FT-IR spectra of spherical flower cluster COFs, polyHIPEs, and polyHIPEs-COFs was conducted, and the results are as follows: Figure 4 As shown, 2831 in the spectrum -1 1364cm -1The peak at [value] originates from the C=C stretching and C=C stretching vibrations of the benzene ring in COFs, polyHIPEs, and polyHIPEs-COFs. Additionally, the spectrum of polyHIPEs-COFs contains another peak at 1608 cm⁻¹. -1 The stress originates from the C=N stretching vibration in the triazine structure of COFs. The figure shows that the C=N stretching vibration in the triazine structure is absent in undoped polyHIPEs, while both COFs and polyHIPEs-COFs contain the triazine structure, confirming the successful synthesis of spherical flower-like COFs.

[0104] 3. The thermal stability of polyHIPEs-COFs was tested by thermogravimetric analysis, and the results are as follows: Figure 5 As shown, under nitrogen atmosphere, when the temperature rises to 250℃, the weight of the spherical flower cluster COFs decreases by about 5%, mainly due to the loss of water in the material. With further temperature increases, the material begins to decompose, and complete decomposition occurs at 650℃, indicating that the polyHIPEs-COFs material possesses good thermal stability.

[0105] 4. A comprehensive comparison of the hydrophilicity and lipophilicity of spherical flower cluster COFs, polyHIPEs, and polyHIPEs-COFs was conducted using deionized water and n-hexane as experimental solvents. The results are as follows: Figure 6 As shown, a water contact angle of 58° and a lipid contact angle of 0° were observed on the surface of COFs, indicating good lipophilicity and some hydrophilicity (A). On the surface of polyHIPEs, a water contact angle of 124° and a lipid contact angle of 0° were observed, indicating that they possess both hydrophobicity and lipophilicity (B). The water and oil contact angles of polyHIPEs-COFs were both 0°, indicating that the prepared polyHIPEs-COFs are amphiphilic (both hydrophilic and lipophilic) (C).

[0106] The polyHIPEs-COFs material with a COFs doping content of 2.1% prepared in Example 5 was used as an adsorbent material to verify its adsorption performance for diamide insecticides under neutral conditions.

[0107] 1. Prepare a mixed insecticide solution of bromocyanamide and chlorantraniliprole with a concentration of 2.5 μg / L and a volume of 40 mL.

[0108] 2. Select a brand new solid-phase extraction column with a sieve plate (3mL×9.00mm, Bojin Instruments Co., Ltd., China). Grind 50mg of polyHIPEs-COFs material into a fine powder and uniformly fill it into the solid-phase extraction column. To fix the material and prevent gaps, cover it with a sieve plate. Then, activate the filled polyHIPEs-COFs solid-phase extraction column by sequentially passing 10mL of methanol and 5mL of water at a flow rate of 1.00mL / min.

[0109] 3. Take 40 mL of the pesticide mixed standard solution into a solid-phase extraction column at a flow rate of 2.00 mL / min, collect the residual liquid after adsorption, pass it through a 0.22 μm filter membrane, and then use a high-performance liquid chromatograph to detect the concentration of the target analyte.

[0110] 4. The adsorbed material was desorbed by using 1 mL of methanol / water (70:30, V / V) to desorb the analytes, with an enrichment factor of 40. The desorbed solution V1 (mL) was collected and analyzed by high performance liquid chromatography.

[0111] The results are as follows Figure 7 As shown in the figure, the adsorption capacities of the prepared adsorbent material for bromocyanamide and chlorantraniliprole are 1.11 and 1.51 mg / g, respectively, which indicates that polyHIPEs-COFs have good adsorption performance for diamide insecticides.

[0112] To evaluate the interference resistance of polyHIPEs-COFs, cypermethrin, imidacloprid, and chlorpyrifos were selected as three coexisting insecticides. The results are as follows: Figure 8 As shown in the figure, at the same concentration (2.5 μg / L), when single or multiple coexisting insecticides are present, the adsorption efficiency of polyHIPEs-COFs for cyantraniliprole and chlorantraniliprole remains above 93%. This indicates that polyHIPEs-COFs have good selectivity for cyantraniliprole and chlorantraniliprole.

[0113] To evaluate the effectiveness of polyHIPEs-COFs materials in practical applications against diamide insecticides, their regeneration performance was investigated. The results are as follows: Figure 9 As shown, after 10 adsorption-desorption cycles, the desorption efficiency of polyHIPEs-COFs remained above 94%. This result demonstrates that polyHIPEs-COFs have good reusability.

[0114] The polyHIPEs-COFs material with a COFs doping content of 2.1% prepared in Example 5 was used as an adsorbent material in actual vegetable samples to verify its adsorption-desorption performance for diamide insecticides.

[0115] The processed eggplant, tomato, and pepper vegetable samples were prepared into spiked sample solutions for spiked recovery experiments. The chromatograms are shown below. Figure 10 As shown in Table 2, the recoveries of bromocyanamide and chlorantraniliprole in actual samples are as follows.

[0116] Table 2

[0117]

[0118] Depend on Figure 10 The relative recoveries of spiked cyantraniliprole and chlorantraniliprole in this experiment ranged from 83.39% to 99.29%, with an RSD of less than 3.52%. The results indicate that this method is highly accurate and has minimal matrix effect, making it suitable for the separation and determination of trace amounts of cyantraniliprole and chlorantraniliprole in vegetables.

[0119] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a COFs-doped high internal phase emulsion-based porous carbon material, characterized in that, Specifically, the following steps are included: S1. Preparation of spherical flower cluster-shaped COFs materials; (1) Weigh 17.8 mg of 4,4′,4′-(1,3,5-triazine-2,4,6-triyl)triphenylamine (TAPT) and 15.5 mg of 2,3,5,6-tetrafluoroterephthalaldehyde (TFA) and place them in a centrifuge tube. Add 2.20 mL of dioxane and 2.80 mL of mesitylene mixed organic solvent and sonicate for 5 min to ensure thorough dispersion. (2) Add 0.4 mL of 12 M HAc, shake in a vortex mixer for 30 s, and let stand at room temperature for 24 h to obtain a yellow turbid liquid; (3) Centrifuge, collect the yellow solid and wash it with THF, acetonitrile and ethanol in sequence; (4) The washed solid was placed in an oven and vacuum dried at 60°C for 24 hours to obtain spherical flower cluster COFs material; S2. Dispersion and modification of COFs in aqueous phase; PVP was added to water and ultrasonically treated, and then spherical flower cluster COFs material was added and stirred to form a uniformly dispersed aqueous phase. Preparation of S3 and polyHIPEs-COFs; An oil phase containing Span80, DVB, STY, and AIBN was mixed and stirred with an aqueous phase containing PVP-COFs to form a uniform high internal phase emulsion. Then, a thermal polymerization reaction was carried out at 65°C. The reaction residue was removed by washing with water and ethanol, and the polyHIPEs-COFs were obtained by freeze drying. The doping amount of COFs was 0.9-2.1%.

2. The method for preparing a COFs-doped high internal phase emulsion-based porous carbon material according to claim 1, characterized in that: The mass of PVP used in step S2 is 13.4g, the mass of COFs material is 0.6g, and the volume of water is 100mL.

3. The method for preparing a COFs-doped high internal phase emulsion-based porous carbon material according to claim 2, characterized in that: The oil phase in step S3 contains 150 μL of Span80, 250 μL of DVB, 500 μL of STY, and 20 mg of AIBN.

4. The method for preparing a COFs-doped high internal phase emulsion-based porous carbon material according to claim 1, characterized in that: In step S3, the internal phase ratio of the high internal phase emulsion is 83%.

5. The method for preparing a COFs-doped high internal phase emulsion-based porous carbon material according to claim 1, characterized in that: The freeze-drying conditions in step S3 are -30℃ for 24 hours.

6. A COFs-doped high internal phase emulsion-based porous carbon material, characterized in that: The porous carbon material is prepared by the preparation method described in any one of claims 1-5.

7. The application of the COFs-doped high internal phase emulsion-based porous carbon material according to claim 6 in the adsorption, separation and detection of diamide insecticides in vegetables.

8. The application according to claim 7, characterized in that, Specifically, the following steps are included: (1) Prepare a standard solution of diamide insecticide; (2) Grind polyHIPEs-COFs material into fine powder, fill it evenly into a solid phase extraction column, and then activate the filled polyHIPEs-COFs solid phase extraction column with methanol and water in sequence. (3) The insecticide standard solution is transported through a solid phase extraction column. After adsorption and enrichment, the residual liquid is collected, filtered, and the concentration of the insecticide is detected by high performance liquid chromatography. (4) The adsorbed material was desorbed by using 1 mL of methanol / water to remove the pesticide. The desorbed liquid was collected and analyzed by high performance liquid chromatography.

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