Preparation and application of a dopamine-imprinted covalent organic framework material

Abstract

This invention relates to the preparation and application of a dopamine-imprinted covalent organic framework (COF) material. Using fluoroquinolone antibiotics (FQs) such as enrofloxacin as model analytes and template molecules, imprinted cavities are formed on the surface of the COF through dopamine surface imprinting, constructing a molecularly imprinted covalent organic framework (MI-COF) material with specific recognition ability for FQs. By organically combining the high selectivity of molecular imprinting (MIP) with the high specific surface area and high porosity of the COF, the prepared MI-COF, as an adsorbent, exhibits excellent enrofloxacin adsorption performance, with an adsorption capacity of 581.40 mg g. ‑1 The adsorption rate is fast. Furthermore, MI-COF exhibits high selectivity for FQs recognition. This invention not only provides a method for preparing dopamine surface-imprinted covalent organic framework materials, but also offers a new solution for enriching the types of FQs solid-phase extraction adsorbents and promoting the development of efficient and accurate FQs analysis.

Description

Technical Field

[0001] This invention specifically relates to the preparation and application of a dopamine-imprinted covalent organic framework material. Background Technology

[0002] Fluoroquinolones (FQs) are a class of effective antimicrobial drugs used in animal husbandry and aquaculture. They can effectively prevent animal diseases and promote growth. These include ciprofloxacin (CIP), enrofloxacin (ENR), norfloxacin (NOR), ofloxacin (FLO), and lomefloxacin (LOM), among others. Ciprofloxacin (CIP), enrofloxacin (ENR), and norfloxacin (NOR) are the most commonly used in veterinary and clinical applications. However, excessive abuse or overuse can directly lead to excessive residues of harmful substances in animal-derived foods. Long-term consumption can cause various adverse reactions in consumers' gastrointestinal, nervous, and immune systems, directly threatening their health.

[0003] Currently, the main methods for determining free radicals (FQs) include high-performance liquid chromatography (HPLC) (GB 29692-2013) and liquid chromatography-tandem mass spectrometry (LC-MS / MS) (GB 31658.17-2021; GB / T 20366-2006). However, FQs residues are low, and food matrices are complex (high fat, protein, or sugar content, etc.), so sample pretreatment is usually required before instrumental analysis to remove background interference and enrich low concentrations of FQs antibiotics. Therefore, preparing a highly efficient extractant for sample pretreatment plays an important role in the highly sensitive detection of FQs.

[0004] Covalent organic frameworks (COFs), as a novel type of porous crystalline organic polymer, possess advantages such as porous channels, high order, large surface area, and abundant active sites, leading to their widespread application in sample pretreatment. COFs are covalently linked long-range ordered structures with highly tunable composition and function. Depending on the target molecule, various functional sites can be introduced into COFs through direct polymerization and post-modification strategies to enhance interactions with specific molecules. However, most COFs recognize targets based on single or non-specific interactions, such as electrostatics, hydrogen bonding, π-π interactions, and van der Waals interactions. Therefore, COFs exhibit limited selectivity in molecular recognition and are easily affected by matrix interference in complex sample matrices.

[0005] Molecularly imprinted polymers (MIPs) are polymer materials that specifically recognize target molecules. These materials are formed through polymerization reactions between functional monomers, crosslinking agents, and template molecules. The template molecules are imprinted within the polymer after removal, creating imprinted cavities with the same shape and size as the template molecules and complementary functional groups. MIPs are widely used in solid-phase extraction, chromatographic separation, biosensors, and membrane separation. However, MIPs still have limitations, such as inaccurate recognition due to the binding sites being mostly located inside the material, difficulty in eluting template molecules, and ineffective separation of target compounds. Furthermore, the availability of monomers is limited, resulting in insufficient adsorption capacity and a small number of imprinted sites, which restricts their widespread application.

[0006] Therefore, this invention is the first to propose combining the structural rigidity, fast mass transfer rate, and large specific surface area of ​​irreversibly linked COFs with the high selectivity of molecular imprinting to prepare an extraction adsorbent with high adsorption and high specific recognition capabilities, which is of great significance in the field of food sample pretreatment. Summary of the Invention

[0007] Objective: This invention addresses the challenge of complex sample pretreatment before fluoroquinolone instrument detection by providing a method for preparing dopamine-imprinted covalent organic framework materials and their applications. This method utilizes carboxylated COF as the matrix material to prepare MI-COF via dopamine surface imprinting, exhibiting high adsorption capacity and selectivity for fluoroquinolones, and the preparation method is simple. This invention not only provides a new method for the preparation of MI-COF but also enriches the types of solid-phase extraction adsorbents, promoting the development of rapid and accurate fluoroquinolones analysis.

[0008] Technical solution: To achieve the above objectives, the technical solution adopted by this invention is as follows:

[0009] The first objective of this invention is to provide a method for preparing a dopamine-imprinted covalent organic framework material. The method includes polymerizing dopamine onto the surface of a covalent organic framework to obtain a material with surface-imprinted cavities. The method comprises the following steps: adding a carboxylated covalent organic framework (COF-COOH) and a template molecule fluoroquinolone (ENR) to a Tris buffer solution, then adding dopamine, and finally eluting to remove the template molecule fluoroquinolone to obtain the dopamine-imprinted covalent organic framework material (MI-COF). The fluoroquinolone includes any one of ciprofloxacin (CIP), enrofloxacin (ENR), and norfloxacin (NOR).

[0010] Optionally, in one embodiment of the present invention, the mass ratio of the carboxylated covalent organic framework, the template molecule enrofloxacin, and dopamine is 2:(0.5-2):(0.5-2), preferably 2:1:1.

[0011] Optionally, in one embodiment of the present invention, the amount of the template molecule enrofloxacin added to the Tris buffer is 0.5-2 mg / mL, preferably 1 mg / mL.

[0012] Optionally, in one embodiment of the present invention, the Tris buffer is a Tris hydrochloride buffer with different pH values, wherein the Tris buffer with different pH values ​​is Tris hydrochloride with pH 5-9, including different pH values ​​such as pH 6, pH 7, pH 8, and pH 9, and preferably Tris hydrochloride with pH 8.

[0013] Optionally, in one embodiment of the present invention, the carboxylated covalent organic framework and the template molecule enrofloxacin are added to Tris buffer and stirred for 1-3 hours, preferably 2 hours, and then dopamine is added and stirred for 3-8 hours, preferably 5 hours.

[0014] Optionally, in one embodiment of the present invention, the elution uses a methanol-acetic acid solution with a volume ratio of 90:10-50:50, preferably 70:30.

[0015] Optionally, in one embodiment of the present invention, the method for preparing the carboxylated covalent organic framework includes: adding the covalent organic framework (COF) to a 20% (m / v) sodium hydroxide ethanol aqueous solution, heating to 80-120°C, refluxing for 1-4 days, preferably 3 days, and cooling to room temperature; rinsing and then redispersing the precipitate in a 0.1-5M hydrochloric acid solution, preferably 1M hydrochloric acid, refluxing and heating to 80-120°C, preferably 120°C, for 0.5-4 hours, preferably 2 hours, and then washing and drying to obtain the carboxylated covalent organic framework (COF-COOH).

[0016] Optionally, in one embodiment of the present invention, the volume ratio of ethanol to water in the sodium hydroxide ethanol aqueous solution is 9:1 to 1:1, preferably 1:1.

[0017] Optionally, in one embodiment of the present invention, the amount of the covalent organic framework (COF) added to the sodium hydroxide ethanol aqueous solution is 1-5 mg / mL, preferably 2 mg / mL.

[0018] Optionally, in one embodiment of the present invention, the preparation method of the covalent organic framework (COF) includes: mixing 2,3,6,7,10,11-hexahydroxytriphenyl (HHTP), tetrafluoroterephthalonitrile (TFPN) and 1,4-dioxane evenly, adding triethylamine, subjecting the mixture to freeze-thaw-circulate degassing, and then reacting it in an oil bath at 80-120°C. The resulting powder is filtered through tetrahydrofuran, washed, and dried to obtain the covalent organic framework.

[0019] Optionally, in one embodiment of the present invention, the molar ratio of 2,3,6,7,10,11-hexahydroxytriphenyl (HHTP), tetrafluoroterephthalonitrile (TFPN) and triethylamine is (0.0928-0.1):(0.138-0.6):(0.560-1.0), preferably 0.0928:0.138:0.560.

[0020] Optionally, in one embodiment of the present invention, the amount of 1,4-dioxane added is 1-3 mL of 1,4-dioxane corresponding to 0.138 mol tetrafluoroterephthalonitrile (TFPN), preferably 2 mL.

[0021] Optionally, in one embodiment of the present invention, the oil bath reaction time is 1-4 days, preferably 3 days.

[0022] Optionally, in one embodiment of the present invention, the method includes the following steps:

[0023] (1) 0.0928 mol of 2,3,6,7,10,11-hexahydroxytriphenyl (HHTP), 0.138 mol of tetrafluoroterephthalonitrile (TFPN), and 2.0 mL of 1,4-dioxane were added to a 15 mL heat-resistant tube and ultrasonically dispersed. Subsequently, 0.560 mol of triethylamine was slowly added to the mixture, and the mixture was subjected to three freeze-thaw-cycle degassing cycles. The mixture was reacted in an oil bath at 120 °C for 3 days. The resulting powder was filtered through tetrahydrofuran and thoroughly washed. It was then vacuum dried at 60 °C to obtain a covalent organic framework (COF).

[0024] (2) Add 100 mg COF to 50 mL of 20% (m / v) sodium hydroxide (NaOH) solution (H2O:ethanol = 1:1), heat to 120 °C, reflux for 3 days, cool to room temperature, and rinse with deionized water. Then, redisperse the precipitate in 2 mL of 1 M hydrochloric acid (HCl) solution, reflux and heat to 120 °C for 2 hours, wash with deionized water and tetrahydrofuran, and vacuum dry overnight to obtain carboxylated COF (COF-COOH);

[0025] (3) Synthesis of surface-imprinted COF (MI-COF) by dopamine self-polymerization: First, 20 mg COF-COOH and 10 mg enrofloxacin (ENR) were added to 10 mL Tris HCl (10 mM, pH 8.0) and stirred for 2 hours. Then, 10 mg dopamine was added and stirred for 5 hours. Finally, the synthesized complex was eluted with methanol-acetic acid (70:30, v / v) to remove the template molecule ENR until there was no UV-vis absorption, thus obtaining MI-COF.

[0026] A second objective of this invention is to provide a dopamine surface-imprinted covalent organic framework material prepared by any of the methods described above.

[0027] Optionally, in one embodiment of the present invention, the performance characteristics of the dopamine surface-imprinted covalent organic framework material include: contact angle and zeta potential, wherein the contact angle is less than 10°, and in some examples, the contact angle is 7.2°; the negative zeta potential is greater than 38mV, and in some examples, the negative zeta potential is 40.93mV.

[0028] A third objective of this invention is to provide a fluoroquinolone adsorbent comprising a dopamine surface-imprinted covalent organic framework material as described above.

[0029] Optionally, in one embodiment of the present invention, the adsorbent has an adsorption capacity greater than 500 mg / g. -1 .

[0030] Optionally, in one embodiment of the present invention, the adsorbent has an adsorption capacity greater than 550 mg / g. -1 In some embodiments, the concentration can be as high as 581.40 mg g. -1 .

[0031] Optionally, in one embodiment of the present invention, the adsorption rate is such that adsorption equilibrium is reached within 30 minutes.

[0032] The fourth objective of this invention is to provide a fluoroquinolone adsorption method, using dopamine surface-imprinted covalent organic framework materials or adsorbents as described above as fluoroquinolone adsorbents, i.e., using the above-described MI-COF as an adsorbent for FQs extraction.

[0033] Optionally, in one embodiment of the present invention, the FQs include any one of ciprofloxacin (CIP), enrofloxacin (ENR), and norfloxacin (NOR).

[0034] Optionally, in one embodiment of the present invention, the method for adsorbing FQs includes the following steps: adding the dopamine surface-imprinted covalent organic framework material or the adsorbent to a solution containing fluoroquinolone for fluoroquinolone extraction.

[0035] In one embodiment of the present invention, the preparation method uses a dopamine surface imprinting method to prepare MI-COF, thereby achieving highly selective extraction and adsorption of FQs.

[0036] Beneficial effects:

[0037] (1) This invention solves the problem of difficult pretreatment of complex samples before fluoroquinolone instrument detection. It innovatively combines the high selectivity of molecular imprinting with the advantages of high stability, high mass transfer rate, and large specific surface area of ​​COFs to design and synthesize MI-COF adsorbents with high selectivity for fluoroquinolones. Compared to dynamic covalent organic frameworks, the irreversible linkage structure ensures the stable existence of imprinted sites and promotes the recycling of materials.

[0038] (2) In addition, carboxylated COFs not only provide adsorption sites for FQs, but also promote interaction with amino groups on dopamine. Using dopamine as a functional monomer and crosslinking agent, imprinted cavities are formed on the COF surface through simple self-polymerization adhesion, thereby improving the mass transfer rate.

[0039] (3) The prepared MI-COF has a large adsorption capacity and a high adsorption rate, which is beneficial to improving the solid phase extraction performance. Attached Figure Description

[0040] Figure 1 Synthesis diagram for MI-COF preparation;

[0041] Figure 2 X-ray powder diffraction (PXRD) patterns of COF, COF-COOH, and MI-COF prepared in Example 1;

[0042] Figure 3 The images are scanning electron microscope (SEM) images, where (a) is a COF-COOH image and (b) is a MI-COF image.

[0043] Figure 4 Contact angle diagram;

[0044] Figure 5 This is a Zeta potential diagram;

[0045] Figure 6 The adsorption isotherm of MI-COF for ENR is shown.

[0046] Figure 7 The adsorption kinetics curve of MI-COF for ENR is shown.

[0047] Figure 8 This is the selective adsorption diagram of MI-COF. Detailed Implementation

[0048] This invention relates to the preparation and application of a dopamine-imprinted covalent organic framework (MI-COF) material. Using fluoroquinolones such as enrofloxacin as template molecules, MI-COF is constructed by forming imprinted cavities on the surface of the covalent organic framework through dopamine surface imprinting, thereby creating a material with specific recognition ability for fluoroquinolone antibiotics (FQs). By organically combining the high selectivity of molecular imprinting (MIP) with the high specific surface area and high porosity of COF, the prepared MI-COF exhibits excellent ENR adsorption performance as an adsorbent, with an adsorption capacity reaching 581.40 mg g. -1 The adsorption rate is fast. Furthermore, MI-COF exhibits high selectivity for FQs recognition. This invention not only provides a method for preparing dopamine surface-imprinted covalent organic framework materials, but also offers a new solution for enriching the types of FQs solid-phase extraction adsorbents and promoting the development of efficient and accurate FQs analysis.

[0049] The present invention will be further described below with reference to the accompanying drawings and embodiments. The present invention can be better understood from the following embodiments. However, those skilled in the art will readily understand that the specific material ratios, process conditions, and results described in the embodiments are for illustrative purposes only and should not, and will not, limit the present invention as described in detail in the claims.

[0050] Example 1: Preparation of MI-COF

[0051] Preparation of dopamine-imprinted covalent organic framework materials: such as Figure 1 The diagram shown illustrates the synthesis of MI-COF. MI-COF was prepared by self-polymerization on the COF surface using dopamine as a functional monomer and crosslinking agent, specifically including the following steps:

[0052] (1) 0.0928 mol of 2,3,6,7,10,11-hexahydroxytriphenyl (HHTP), 0.138 mol of tetrafluoroterephthalonitrile (TFPN), and 2.0 mL of 1,4-dioxane were added to a 15 mL heat-resistant tube and ultrasonically dispersed. Subsequently, 0.560 mol of triethylamine was slowly added to the mixture, and the mixture was subjected to three freeze-thaw-cycle degassing cycles. The reaction was carried out in an oil bath at 120 °C for 3 days. The resulting powder was filtered through tetrahydrofuran and thoroughly washed. It was then vacuum dried at 60 °C to obtain a covalent organic framework (COF).

[0053] (2) Add 100 mg COF to 50 mL of 20% (m / v) sodium hydroxide (NaOH) solution (H2O:ethanol = 1:1), heat to 120 °C, and reflux for 3 days. After cooling to room temperature, rinse with deionized water. Then, redisperse the precipitate in 2 mL of 1 M hydrochloric acid (HCl) solution and reflux to 120 °C. After 2 hours, wash with deionized water and tetrahydrofuran, and vacuum dry overnight to obtain carboxylated COF (COF-COOH).

[0054] (3) Synthesis of surface-imprinted COF (MI-COF) via dopamine self-polymerization. First, 20 mg COF-COOH and 10 mg enrofloxacin (ENR) were added to 10 mL Tris HCl (10 mM, pH 8.0) and stirred for 2 hours. Then, 10 mg dopamine was added and stirred for 5 hours. Finally, the synthesized complex was eluted with methanol-acetic acid (70:30, v / v) to remove the template molecule ENR until no UV-vis absorption was observed, yielding MI-COF.

[0055] Figure 2 The X-ray powder diffraction (PXRD) patterns of COF, COF-COOH, and MI-COF prepared sequentially in this embodiment are shown. As can be seen from the figures, the COF prepared in this embodiment has high crystallinity, with a strong peak at 4.2° and smaller diffraction peaks at 8.4° and 27.1°. After dopamine polymerization, MI-COF also exhibits a certain crystal structure, indicating that COF possesses high stability and a crystalline structure.

[0056] Scanning electron microscope Figure 3 (a) shows that COF-COOH exhibits a spindle-shaped structure and has a relatively smooth surface. Figure 3 (b) is an electron microscope image after the imprinting. It can be clearly seen that the MI-COF surface becomes thicker and rougher, proving that dopamine was successfully polymerized on the COF-COOH surface.

[0057] The contact angle test results of MI-COF are as follows: Figure 4 The results showed that after dopamine imprinting, the hydrophilicity of MI-COF increased, with a contact angle of less than 10°, specifically 7.2°, which is much smaller than the contact angle of COF-COOH, which is as high as 52.3°. This proves that dopamine was successfully polymerized on the surface of COF-COOH.

[0058] The zeta potential test results of MI-COF are as follows: Figure 5 The results showed that after dopamine imprinting, compared with the negative potential of COF-COOH which was only 34.87mV, the surface negative charge of MI-COF increased, and the negative potential increased to 40.93mV, further proving that dopamine was successfully polymerized on the surface of COF-COOH.

[0059] Example 2: Study on the isothermal adsorption capacity of MI-COF for ENR

[0060] The isothermal adsorption capacity of ENR was investigated using MI-COF prepared in Example 1 as an adsorbent.

[0061] Accurately weigh 1 mg of MI-COF powder into a 5 mL centrifuge tube, and add 4 mL of ENR (60-300 mg / mL) to the centrifuge tube. -1 The solution was shaken at 150 rpm for 2 hours. After filtration through a 0.22 μm filter membrane, the concentration of ENR in the solution was determined using UV-Vis.

[0062] like Figure 6 The adsorption isotherms shown indicate that the MI-COF of the present invention has good adsorption capacity for ENR, and the adsorption capacity can reach 581.4 mg g at adsorption equilibrium. -1 .

[0063] Example 3: Adsorption kinetics of ENR by MI-COF

[0064] The adsorption kinetics of ENR were investigated using MI-COF prepared in Example 1 as an adsorbent.

[0065] Accurately weigh 10 mg of MI-COF powder into a 50 mL centrifuge tube, and add 40 mL of 100 mg / mL solution to the centrifuge tube. - 1 ENR was measured at 150 rpm on a shaker, with a sample taken at regular intervals. The solution was filtered through a 0.22 μm filter and the concentration of ENR in the solution was determined using UV-Vis.

[0066] like Figure 7 Adsorption kinetics curves show that the MI-COF of the present invention has a fast adsorption rate for ENR and can reach adsorption equilibrium within 30 min.

[0067] Example 4: Selectivity study of MI-COF on ENR

[0068] The adsorption selectivity was investigated using the MI-COF prepared in Example 1 as an adsorbent.

[0069] Ciprofloxacin (CIP), norfloxacin (NOR), flumethinazole (FLU), sulfamethoxazole (SMZ), and chloramphenicol (CAP) were selected as structural analogs, and adsorption tests were performed according to the method in Example 2.

[0070] like Figure 8The selective adsorption diagram of MI-COF shown indicates that MI-COF has adsorption properties for all FQs. Therefore, MI-COF prepared using ENR as a template molecule can be used to adsorb FQs, that is, MI-COF can be used as an extraction adsorbent for FQs extraction.

[0071] Furthermore, it can be seen that the MI-COF prepared using ENR as a template molecule in this embodiment exhibits a higher adsorption capacity for ENR than other similar compounds. Compared to ENR, the selective imprinting factors of MI-COF for NOR, CIP, FLU, SMZ, and CAP are 1.13, 1.27, 3.24, 3.68, and 16.9, respectively. MI-COF demonstrates a high selective recognition ability for the three interfering compounds FLU, SMZ, and CAP, while also showing good adsorption effects for the other two FQs antibiotics, CIP and NOR. This is because after removing the template molecule, the surface has recognition cavities and functional groups, as well as cavities that match the template molecule, allowing for the recognition and adsorption of the template molecule. The three FQs antibiotics, ENR, CIP, and NOR, have similar structures, thus effectively adsorbing FQs.

[0072] Finally, it should be noted that the above embodiments used ENR as a template molecule to prepare MI-COF, which was then used as an extraction adsorbent for FQs extraction. Similarly, when other FQs such as NOR and CIP are used as template molecules, MI-COF with corresponding adsorption selectivity can also be prepared and used as an extraction adsorbent for FQs extraction. This will not be elaborated further in this invention, but it still falls within the protection scope of this invention.

[0073] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a dopamine-imprinted covalent organic framework material, characterized in that, The method includes polymerizing dopamine on the surface of a covalent organic framework to obtain a material with a surface-imprinted cavity. Specifically, it includes the following steps: adding a carboxylated covalent organic framework and a template molecule fluoroquinolone to a Tris buffer, then adding dopamine, and finally eluting to remove the template molecule fluoroquinolone to obtain the dopamine surface-imprinted covalent organic framework material. The fluoroquinolone includes any one of ciprofloxacin, enrofloxacin, and norfloxacin.

2. The method according to claim 1, characterized in that, The mass ratio of the carboxylated covalent organic framework, the template molecule enrofloxacin, and dopamine is 2:(0.5-2):(0.5-2). The template molecule enrofloxacin was added to Tris buffer at a concentration of 0.5-2 mg / mL. The Tris buffer solution comprises Tris hydrochloride at pH 5–9; The carboxylated covalent organic framework and the template molecule enrofloxacin were added to Tris buffer and stirred for 1-3 h, followed by the addition of dopamine and stirring for 3-8 h. The elution process uses a methanol-acetic acid solution with a volume ratio of 90:10 to 50:

50.

3. The method according to claim 1, characterized in that, The method for preparing the carboxylated covalent organic framework includes: adding the covalent organic framework to a 20% m / v sodium hydroxide ethanol aqueous solution, heating to 80-120 °C, refluxing for 1-4 days, and cooling to room temperature; rinsing and then redispersing the precipitate in a 0.1-5 M hydrochloric acid solution, refluxing and heating to 80-120 °C, and after 0.5-4 hours, washing and drying to obtain the carboxylated covalent organic framework; In the sodium hydroxide ethanol aqueous solution, the volume ratio of ethanol to water is (1-9):1; The amount of the covalent organic framework added to the sodium hydroxide ethanol aqueous solution is 1-5 mg / mL.

4. The method according to claim 3, characterized in that, The preparation method of the covalent organic framework includes: mixing 2,3,6,7,10,11-hexahydroxytriphenyl, tetrafluoroterephthalonitrile and 1,4-dioxane evenly, adding triethylamine, freezing-thawing-cyclic degassing, and then reacting in an oil bath at 80-120 °C. The resulting powder is filtered with tetrahydrofuran, washed and dried to obtain the covalent organic framework. The molar ratio of 2,3,6,7,10,11-hexahydroxytriphenyl, tetrafluoroterephthalonitrile, and triethylamine is (0.0928-0.1):(0.138-0.6):(0.560-1.0). The amount of 1,4-dioxane added is 0.138 mol tetrafluoroterephthalonitrile, corresponding to the addition of 1-3 mL of 1,4-dioxane; The oil bath reaction time is 1-4 days.

5. A dopamine-imprinted covalent organic framework material, characterized in that, Prepared by the method according to any one of claims 1-4.

6. The dopamine-imprinted covalent organic framework material according to claim 5, characterized in that, The contact angle of the dopamine surface-imprinted covalent organic framework material is less than 10°, and the zeta negative potential is greater than 38 mV.

7. A fluoroquinolone adsorbent, characterized in that, The adsorbent comprises the dopamine surface-imprinted covalent organic framework material as described in claim 5 or 6.

8. The adsorbent according to claim 7, characterized in that, The adsorbent has an adsorption capacity greater than 500 mg g. −1 The adsorption rate reaches adsorption equilibrium within 30 minutes.

9. A method for adsorbing fluoroquinolones, characterized in that, The dopamine surface-imprinted covalent organic framework material as described in any one of claims 5-6 or the adsorbent as described in claim 7 or 8 is used as the fluoroquinolone adsorbent.

10. The method according to claim 9, characterized in that, The method includes the following steps: adding the dopamine surface-imprinted covalent organic framework material or the adsorbent to a solution containing fluoroquinolone for fluoroquinolone adsorption.

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