Preparation method and application of a multi-level pore metal organic framework surface molecular imprinting polymer

Abstract

The application discloses a preparation method and application of a multi-level hole metal organic framework surface molecular imprinting polymer. A functional monomer methacrylic acid and a template molecule bisphenol A are dissolved into ethanol containing a carrier multi-level hole metal organic framework, pre-polymerization is carried out at 20-40 DEG C for 2-8h, a crosslinking agent ethylene glycol dimethacrylate and an initiator azobisisobutyronitrile are added, after ultrasonic and nitrogen protection, thermal polymerization is carried out at 50-70 DEG C for 20-30h, elution and drying are carried out to obtain the multi-level hole metal organic framework surface molecular imprinting polymer. The multi-level hole metal organic framework surface molecular imprinting polymer prepared by the application has strong selective adsorption capacity and high adsorption amount of a target bisphenol A in an aqueous solution, and can be used for separation and enrichment of the bisphenol A in an actual water sample.

Description

A method for preparing surface molecularly imprinted polymers with hierarchical porous metal-organic frameworks and its application. Technical Field

[0001] This invention belongs to the field of preparation of functional polymers and separation and enrichment of bisphenol A, specifically relating to a method for preparing a multi-level porous metal-organic framework surface molecularly imprinted polymer and its application. Background Technology

[0002] Molecularly imprinted polymers (MIPs) are highly cross-linked complexes formed by template molecules and functional monomers. After template removal, the specific recognition sites in MIPs, such as spatial structure, size, and functional groups, closely match the template molecules. This "memory" ability allows for the selective adsorption and recognition of template molecules that coexist with other compounds. Compared to conventional MIPs, surface-imprinted polymers have recognition sites located on the material surface in direct contact with the target molecules, resulting in higher adsorption rates and faster equilibrium adsorption times. The target molecules can also be more easily eluted after adsorption, thus enabling material regeneration. This regenerability gives surface-imprinted polymers a longer lifespan and higher reusability.

[0003] Metal-organic frameworks (MOFs) possess advantages such as porous structure, high specific surface area, tunability and versatility, controlled release and regeneration capabilities, as well as chemical and thermal stability. These advantages make MOFs an ideal support material for constructing efficient, selective, and controllable surface-imprinted polymers. However, traditional MOFs have pore sizes smaller than 2 nm, belonging to microporous structures, which reduces the reaction rate and adsorption capacity during the adsorption process, limiting the application range of MOFs. Summary of the Invention

[0004] The technical problem solved by this invention is to provide a method for preparing a multi-level porous metal-organic framework surface molecularly imprinted polymer. The multi-level porous metal-organic framework surface molecularly imprinted polymer prepared by this method has a strong ability to selectively adsorb the target bisphenol A in aqueous solution and the adsorption capacity is high, which can be used for the separation and enrichment of bisphenol A in actual environmental samples.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a method for preparing a multi-level porous metal-organic framework surface molecularly imprinted polymer, characterized in that the specific process is as follows: the functional monomer methacrylic acid and the template molecule bisphenol A are dispersed in ethanol containing a carrier multi-level porous metal-organic framework, prepolymerized at 20~40℃ for 2~8h, then the crosslinking agent ethylene glycol dimethacrylate and the initiator azobisisobutyronitrile are added, and after ultrasonication and nitrogen protection, thermal polymerization is carried out at 50~70℃ for 20~30h, and after elution and drying, the multi-level porous metal-organic framework surface molecularly imprinted polymer is obtained, wherein the multi-level porous metal-organic framework is prepared by using one or more of sodium dodecyl sulfonate, sodium dodecylbenzene sulfonate, sodium dodecyl sulfate or dodecyltrimethylammonium bromide as a soft template.

[0006] Further specified, the molar ratio of the template molecule, functional monomer and crosslinking agent is 0.3~1.5:2~4:10~20.

[0007] Further specifying, the specific preparation process of the hierarchical porous metal-organic framework is as follows: a soft template and copper nitrate trihydrate are mixed and added to trimesic acid, and then reacted at 110~130℃ for 10~14h to obtain the hierarchical porous metal-organic framework, wherein the soft template is one or more of sodium dodecyl sulfonate, sodium dodecylbenzene sulfonate, sodium dodecyl sulfate or dodecyltrimethylammonium bromide.

[0008] Further specified, the molar ratio of the soft template and copper nitrate trihydrate is 0.05~0.5:1.

[0009] Further specifying, the elution process uses Soxhlet extraction, specifically, Soxhlet extraction with a methanol and acetic acid mixture at a volume ratio of 9:1 for 48 hours.

[0010] The multi-level porous metal-organic framework surface molecularly imprinted polymer of the present invention is used for the separation and enrichment of bisphenol A in actual environmental samples. The specific process is as follows: the multi-level porous metal-organic framework surface molecularly imprinted polymer is placed in an actual environmental sample containing bisphenol A to achieve the adsorption of bisphenol A in the environmental water sample, and then acetonitrile is used as the elution solvent to achieve the enrichment of bisphenol A and the regeneration and recycling of the multi-level porous metal-organic framework surface molecularly imprinted polymer.

[0011] Further, a hierarchical porous metal-organic framework surface molecularly imprinted polymer was packed into a polypropylene solid-phase extraction column equipped with a sieve plate for the pretreatment of bisphenol A in actual environmental water samples. The spiked experiment results showed that the recovery rate of bisphenol A reached more than 90%, indicating that the hierarchical porous metal-organic framework surface molecularly imprinted polymer can be used for the separation and enrichment of bisphenol A. After more than 10 cycles of use, the adsorption performance of the solid-phase extraction column did not decrease significantly, indicating that the hierarchical porous metal-organic framework surface molecularly imprinted polymer can be regenerated and recycled.

[0012] The hierarchical porous metal-organic framework surface molecularly imprinted polymer of the present invention is used to selectively remove bisphenol A from actual environmental samples. This hierarchical porous metal-organic framework surface molecularly imprinted polymer can selectively adsorb bisphenol A in an aqueous solution containing bisphenol A, bisphenol B, 2,4-dinitrophenol, chloramphenicol and sulfadiazine.

[0013] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0014] 1. This invention provides a multi-level porous organic framework metal material prepared with various surfactants as a carrier for preparing bisphenol A surface-imprinted polymers. The surface-imprinted polymers have properties such as uniform particle size, large adsorption capacity, and strong affinity in water.

[0015] 2. The present invention uses ethanol as the preparation solvent, which on the one hand reduces the secondary damage to the environment caused by non-polar solvents such as acetonitrile and methanol, and on the other hand improves the adsorption capacity of the imprinted polymer. Attached Figure Description

[0016] Figure 1 is a synthetic route diagram of the hierarchical porous metal-organic framework in this invention.

[0017] Figure 2 is a synthetic route diagram of the imprinted polymer in this invention.

[0018] Figure 3 is a diagram showing the adsorption kinetics of the imprinted polymer and the non-imprinted polymer of the present invention.

[0019] Figure 4 shows the adsorption isotherms of the imprinted polymer and the non-imprinted polymer of the present invention.

[0020] Figure 5 shows the competitive adsorption capacity of the imprinted polymer and the non-imprinted polymer of the present invention for different substrates in a mixed solution.

[0021] Figure 6 shows the effect of different types of eluents on the elution effect of bisphenol A when the imprinted polymer of the present invention is used as the packing material of the solid phase extraction column (Note: (1) Methanol (2) Methanol / water = 80 / 20 (3) Methanol / water / acetic acid = 80 / 19 / 1 (4) Methanol / water / acetic acid = 80 / 18 / 2 (5) Acetonitrile (6) Acetonitrile / water = 60 / 40.) Detailed Implementation

[0022] The following embodiments further illustrate the above-described content of the present invention in detail, but it should not be construed as limiting the scope of the subject matter of the present invention to the following embodiments. All technologies implemented based on the above-described content of the present invention fall within the scope of the present invention. Embodiments

[0023] Preparation of hierarchical porous metal-organic framework carrier: Sodium dodecyl sulfate and copper nitrate trihydrate were mixed in a molar ratio of 0.1:1 and then pyromellitic acid was added. The mixture was reacted at 120℃ for 12 h to obtain a hierarchical porous metal-organic framework solid material.

[0024] Preparation of imprinted polymers: Using 30 mL of ethanol as solvent, 44.6 μL (0.5256 mmol) of methacrylic acid (functional monomer), 0.08 g of the above-mentioned hierarchical porous metal-organic framework solid material (carrier), and 0.03 g of bisphenol A (template molecule) were prepolymerized at 30 °C for 4 h. Then, 372 μL (1.971 mmol) of crosslinking agent ethylene glycol dimethacrylate (EDMA) and 20 mg of initiator 2,2-azobisisobutyronitrile (AIBN) were added. After ultrasonication and nitrogen protection, thermal polymerization was initiated at 60 °C for 24 h to obtain the product. The product was then extracted with a methanol / acetic acid mixture (9:1 volume ratio) using a Soxhlet extractor for 48 h and vacuum dried to obtain the imprinted polymer, named Me-HKUST-1@MIP. Non-molecularly imprinted polymers (NIPs) were prepared using the same steps as above, except that no template molecule was added, and were named Me-HKUST-1@NIP. Meanwhile, for comparison, conventional microporous HKUST-1 material was selected as the carrier, and conventional HKUST-1@MIP and conventional HKUST-1@NIP were prepared using the same steps. Examples

[0025] Preparation of hierarchical porous metal-organic framework carrier: Sodium dodecyl sulfate and copper nitrate trihydrate were mixed in a molar ratio of 0.5:1 and then pyromellitic acid was added. The mixture was reacted at 120℃ for 12 h to obtain a hierarchical porous metal-organic framework solid material.

[0026] Preparation of imprinted polymers: Using 30 mL of ethanol as solvent, 44.6 μL (0.5256 mmol) of methacrylic acid (functional monomer), 0.08 g of the above-mentioned hierarchical porous metal-organic framework solid material (carrier), and 0.03 g of bisphenol A (template molecule) were prepolymerized at 30 °C for 4 h. Then, 372 μL (1.971 mmol) of crosslinking agent ethylene glycol dimethacrylate (EDMA) and 20 mg of initiator 2,2-azobisisobutyronitrile (AIBN) were added. After ultrasonication and nitrogen protection, thermal polymerization was initiated at 60 °C for 24 h to obtain the product. The product was then extracted with a methanol / acetic acid mixture (9:1 volume ratio) using a Soxhlet extractor for 48 h and vacuum dried to obtain the imprinted polymer, named Me-HKUST-1@MIP. Non-molecularly imprinted polymers (NIPs) were prepared using the same steps as above, except that no template molecule was added; they were also named Me-HKUST-1@NIP. Examples

[0027] Preparation of hierarchical porous metal-organic framework carrier: Sodium dodecyl sulfate and copper nitrate trihydrate were mixed in a molar ratio of 0.15:1 and then pyromellitic acid was added. The mixture was reacted at 120℃ for 12 h to obtain a hierarchical porous metal-organic framework solid material.

[0028] Preparation of imprinted polymers: Using 30 mL of ethanol as solvent, 44.6 μL (0.5256 mmol) of methacrylic acid (functional monomer), 0.08 g of the above-mentioned hierarchical porous metal-organic framework solid material (carrier), and 0.03 g of bisphenol A (template molecule) were prepolymerized at 30 °C for 4 h. Then, 372 μL (1.971 mmol) of crosslinking agent ethylene glycol dimethacrylate (EDMA) and 20 mg of initiator 2,2-azobisisobutyronitrile (AIBN) were added. After ultrasonication and nitrogen protection, thermal polymerization was initiated at 60 °C for 24 h to obtain the product. The product was then extracted with a methanol / acetic acid mixture (9:1 volume ratio) using a Soxhlet extractor for 48 h and vacuum dried to obtain the imprinted polymer, named Me-HKUST-1@MIP. Non-molecularly imprinted polymers (NIPs) were prepared using the same steps as above, except that no template molecule was added; they were also named Me-HKUST-1@NIP. Examples

[0029] Preparation of hierarchical porous metal-organic framework carrier: Dodecyltrimethylammonium bromide and copper nitrate trihydrate were mixed in a molar ratio of 0.05:1 and then pyromellitic acid was added. The mixture was reacted at 120℃ for 12 h to obtain a hierarchical porous metal-organic framework solid material.

[0030] Preparation of imprinted polymers: Using 30 mL of ethanol as solvent, 44.6 μL (0.5256 mmol) of methacrylic acid (functional monomer), 0.08 g of the above-mentioned hierarchical porous metal-organic framework solid material (carrier), and 0.03 g of bisphenol A (template molecule) were prepolymerized at 30 °C for 4 h. Then, 372 μL (1.971 mmol) of crosslinking agent ethylene glycol dimethacrylic acid (EDMA) and 20 mg of initiator 2,2-azobisisobutyronitrile (AIBN) were added. After ultrasonication and nitrogen protection, thermal polymerization was initiated at 60 °C for 24 h to obtain the product. The product was then extracted with a methanol / acetic acid mixture (9:1 volume ratio) using a Soxhlet extractor for 48 h and vacuum dried to obtain the imprinted polymer, named Me-HKUST-1@MIP. Non-molecularly imprinted polymers (NIPs) were prepared using the same steps as above, except that no template molecule was added; they were also named Me-HKUST-1@NIP. Examples

[0031] Preparation of hierarchical porous metal-organic framework carrier: Dodecyltrimethylammonium bromide and copper nitrate trihydrate were mixed in a molar ratio of 0.1:1 and then pyromellitic acid was added. The mixture was reacted at 120℃ for 12 h to obtain a hierarchical porous metal-organic framework solid material.

[0032] Preparation of imprinted polymers: Using 30 mL of ethanol as solvent, 44.6 μL (0.5256 mmol) of methacrylic acid (functional monomer), 0.08 g of the above-mentioned hierarchical porous metal-organic framework solid material (carrier), and 0.03 g of bisphenol A (template molecule) were prepolymerized at 30 °C for 4 h. Then, 372 μL (1.971 mmol) of crosslinking agent ethylene glycol dimethacrylate (EDMA) and 20 mg of initiator 2,2-azobisisobutyronitrile (AIBN) were added. After ultrasonication and nitrogen protection, thermal polymerization was initiated at 60 °C for 24 h to obtain the product. The product was then extracted with a methanol / acetic acid mixture (9:1 volume ratio) using a Soxhlet extractor for 48 h and vacuum dried to obtain the imprinted polymer, named Me-HKUST-1@MIP. Non-molecularly imprinted polymers (NIPs) were prepared using the same steps as above, except that no template molecule was added; they were also named Me-HKUST-1@NIP. Examples

[0033] Preparation of hierarchical porous metal-organic framework carrier: Dodecyltrimethylammonium bromide and copper nitrate trihydrate were mixed in a molar ratio of 0.15:1 and then pyromellitic acid was added. The mixture was reacted at 120℃ for 12 h to obtain a hierarchical porous metal-organic framework solid material.

[0034] Preparation of imprinted polymers: Using 30 mL of ethanol as solvent, 44.6 μL (0.5256 mmol) of methacrylic acid (functional monomer), 0.08 g of the above-mentioned hierarchical porous metal-organic framework solid material (carrier), and 0.03 g of bisphenol A (template molecule) were prepolymerized at 30 °C for 4 h. Then, 372 μL (1.971 mmol) of crosslinking agent ethylene glycol dimethacrylic acid (EDMA) and 20 mg of initiator 2,2-azobisisobutyronitrile (AIBN) were added. After ultrasonication and nitrogen protection, thermal polymerization was initiated at 60 °C for 24 h to obtain the product. The product was then extracted with a methanol / acetic acid mixture (9:1 volume ratio) using a Soxhlet extractor for 48 h and vacuum dried to obtain the imprinted polymer, named Me-HKUST-1@MIP. Non-molecularly imprinted polymers (NIPs) were prepared using the same steps as above, except that no template molecule was added; they were also named Me-HKUST-1@NIP. Examples

[0035] 10 mg of conventional HKUST-1@MIP and conventional HKUST-1@NIP, as well as Me-HKUST-1@MIP and Me-HKUST-1@NIP prepared in Example 1, were respectively tested at 25°C and at different concentrations (10 mg / L) in 10 mL. -1 30mg L -1 50mg L -1 A mixture of bisphenol A and an aqueous solution was prepared, and the mixture was shaken at room temperature for a certain period of time (0–240 min). The supernatant was then collected, and the absorbance at 277 nm was measured using a UV spectrophotometer. The results are shown in Figure 3. Example

[0036] Under different temperature conditions (25℃, 35℃, 45℃), 10 mg of conventional HKUST-1@MIP and conventional HKUST-1@NIP, as well as Me-HKUST-1@MIP and Me-HKUST-1@NIP prepared in Example 1, were mixed with 10 mL of bisphenol A aqueous solution (0.5~500 mg L). -1 After adsorption by shaking at room temperature for 3 hours, the supernatant was collected and the absorbance at 277 nm was measured using a UV spectrophotometer. The results are shown in Figure 4. Example

[0037] 5 mg of Me-HKUST-1@MIP, Me-HKUST-1@NIP, HKUST-1@MIP, and HKUST-1@NIP were added to 10 mL of a 50 mg L solution, respectively. -1 Aqueous solutions of bisphenol A (BPA), bisphenol B (BPB), 2,4-dinitrophenol (2,4-NP), chloramphenicol (CAP), and sulfadiazine (SD) were adsorbed at room temperature with shaking for 3 h. The absorbance of the supernatant at 277 nm was measured using a UV spectrophotometer. The results are shown in Figure 5. The adsorption capacities of Me-HKUST-1@MIP for the four substrates were 57.2 mg / g. -1 9.9mg g -1 4.7mg g -1 and 5.2 mg g -1 The data above shows that the polymer Me-HKUST-1@MIP exhibits excellent competitive selection for BPA. This indicates that the polymer Me-HKUST-1@MIP maintains a very good adsorption effect on BPA even under near-real-world complex conditions, making it significant for the removal of BPA from actual water samples. Example

[0038] 30 mg of Me-HKUST-1@MIP material prepared in Example 1 was loaded into a 3 mL polypropylene column to prepare a self-made solid-phase extraction microcolumn. A concentration of 1 mg L... -1 Bisphenol A aqueous solution was passed through a solid-phase extraction column, eluted with 2 mL of water, and the bisphenol A content in the eluent was detected by HPLC. This method was also used to optimize the eluent, and the results are shown in Figure 6.

[0039] The above embodiments describe the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are only illustrative of the principles of the present invention. Various changes and modifications can be made to the present invention without departing from the scope of the principles of the present invention, and all such changes and modifications fall within the protection scope of the present invention.

Claims

1. A method for preparing a multi-level porous metal-organic framework surface molecularly imprinted polymer, characterized in that... The specific process is as follows: The functional monomer methacrylic acid and the template molecule bisphenol A are dispersed in ethanol containing a hierarchical porous metal-organic framework (MOF). Prepolymerization is carried out at 20-40°C for 2-8 hours. Then, the crosslinking agent ethylene glycol dimethacrylate and the initiator azobisisobutyronitrile (AIBN) are added. After ultrasonication and nitrogen protection, thermal polymerization is carried out at 50-70°C for 20-30 hours. After elution and drying, a molecularly imprinted polymer on the surface of the hierarchical porous MOF is obtained. The hierarchical porous MOF is formed using one or more of sodium dodecyl sulfonate, sodium dodecylbenzene sulfonate, sodium dodecyl sulfate, or dodecyltrimethylammonium bromide as the soft mold. The template molecule, functional monomer and crosslinking agent are prepared by means of a plate, wherein the molar ratio of the template molecule, functional monomer and crosslinking agent is 0.3~1.5:2~4:10~20; the specific preparation process of the hierarchical porous metal-organic framework is as follows: the soft template and copper nitrate trihydrate are mixed and added to trimesic acid, and then reacted at 110~130℃ for 10~14h to obtain the hierarchical porous metal-organic framework, wherein the soft template is one or more of sodium dodecyl sulfonate, sodium dodecylbenzene sulfonate, sodium dodecyl sulfate or dodecyltrimethylammonium bromide, and the molar ratio of the soft template and copper nitrate trihydrate is 0.05~0.5:

1.

2. The method for preparing the multi-level porous metal-organic framework surface molecularly imprinted polymer according to claim 1, characterized in that: The elution process uses Soxhlet extraction, specifically involving Soxhlet extraction for 48 hours using a methanol and acetic acid mixture with a volume ratio of 9:

1.

3. The application of the hierarchical porous metal-organic framework surface molecularly imprinted polymer prepared according to claim 1 or 2 in the separation and enrichment of bisphenol A in actual environmental samples, characterized in that... The specific application process is as follows: the multi-level porous metal-organic framework surface molecularly imprinted polymer is placed in an actual environmental sample containing bisphenol A to achieve the adsorption of bisphenol A in the environmental water sample, and then acetonitrile is used as the elution solvent to achieve the enrichment of bisphenol A and the regeneration and recycling of the multi-level porous metal-organic framework surface molecularly imprinted polymer.

4. The application according to claim 3, characterized in that: A multi-level porous metal-organic framework surface molecularly imprinted polymer is packed into a polypropylene solid-phase extraction column equipped with a sieve plate to achieve the pretreatment of bisphenol A in actual environmental water samples. The multi-level porous metal-organic framework surface molecularly imprinted polymer can be used for the separation and enrichment of bisphenol A. The multi-level porous metal-organic framework surface molecularly imprinted polymer can be regenerated and recycled.

5. The application of the hierarchical porous metal-organic framework surface molecularly imprinted polymer prepared according to claim 1 or 2 in the selective removal of bisphenol A from actual environmental samples, wherein the hierarchical porous metal-organic framework surface molecularly imprinted polymer can selectively adsorb bisphenol A in an aqueous solution containing bisphenol A, bisphenol B, 2,4-dinitrophenol, chloramphenicol and sulfadiazine.

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