Preparation method and application of magnetic geosmin molecularly imprinted polymer

Abstract

The invention relates to the technical field of environmental engineering, and discloses a preparation method and application of a magnetic geosmin molecularly imprinted polymer, and the preparation method comprises the following steps: (1) reacting surface-functionalized nanoparticles with a silane coupling agent KH-570 in a toluene solution to obtain modification; (2) dissolving a virtual template molecule cis-decahydro-1-naphthol and a functional monomer methacrylic acid in acetonitrile, carrying out a prepolymerization reaction, then adding the modified cross-linking agent ethylene dimethacrylate obtained in the step (1) and an initiator azodiisobutyronitrile, and carrying out a polymerization reaction at 50-60 DEG C under the protection of nitrogen; and (3) after the reaction is completed, separating a product through an external magnetic field, washing and drying to obtain a crude product. The adsorption capacity of the material to geosmin is far higher than that of a non-imprinted material (the adsorption capacity reaches 5.58 mg / g in an embodiment 3), the material has excellent complex matrix interference resistance, and a target object can be accurately captured from coexisting substances such as soluble organic matter and humus.

Description

Technical Field

[0001] This invention relates to the field of environmental engineering technology, specifically to a method for preparing a magnetic geosmin molecularly imprinted polymer and its application. Background Technology

[0002] Geosmosin is a typical trace odor-causing substance produced by the metabolism of cyanobacteria and actinomycetes. Even at concentrations in the ng / L range, it can severely degrade the sensory quality of drinking water, raising public concern. Currently, the detection of geosmosin mainly relies on gas chromatography-mass spectrometry (GC-MS), but its direct analysis in complex environmental water samples faces challenges such as strong matrix interference and insufficient sensitivity. Therefore, an efficient pretreatment enrichment step is crucial. Traditional pretreatment methods such as solid-phase extraction and liquid-liquid extraction generally suffer from problems such as cumbersome operation, long processing time, large amounts of organic solvents, and limited selective adsorption capacity for geosmosin, making it difficult to meet the needs of rapid and accurate screening of large numbers of samples.

[0003] Molecular imprinting technology can construct polymers with specific recognition sites for target molecules, offering a potential solution to the aforementioned selectivity challenges. However, traditional molecularly imprinted polymers, when used as adsorbents, often suffer from inherent drawbacks such as template molecule leakage interfering with detection and cumbersome centrifugation / filtration separation steps. While combining magnetic materials with molecular imprinting technology can achieve rapid separation using magnetic fields, achieving efficient and highly selective enrichment of geosmin in complex aqueous matrices, while simultaneously improving adsorption capacity and kinetic performance, remains a key technical problem that urgently needs to be optimized and solved in this field. Summary of the Invention

[0004] To address the problems mentioned in the background section, the present invention provides the following technical solution: a method for preparing a magnetic earth ozone molecularly imprinted polymer, comprising the following steps:

[0005] (1) Functionalizing the surface Nanoparticles were reacted with silane coupling agent KH-570 in toluene solution to obtain modified [product / product]. ;

[0006] (2) The virtual template molecule cis-decahydro-1-naphthol and the functional monomer methacrylic acid were dissolved in acetonitrile for a prepolymerization reaction, and then the modified molecule obtained in step (1) was added. The crosslinking agent ethylene glycol dimethacrylate and the initiator azobisisobutyronitrile were polymerized at 50-60°C under nitrogen protection.

[0007] (3) After the reaction is complete, the product is separated by an external magnetic field, washed and dried to obtain the crude product;

[0008] (4) Remove the template molecules by Soxhlet extraction until the template molecules are no longer detectable by GC-MS to obtain the magnetic geosmin molecular imprinted polymer.

[0009] Preferably, in step (1), The dosage was 0.5~1 g. The addition of silane coupling agent KH-570 was carried out under ultrasonic treatment and continuous stirring. The reaction time was 12 hours and the reaction was carried out under nitrogen protection.

[0010] Preferably, in step (2), the molar ratio of the virtual template molecule to the functional monomer methacrylic acid is 1:3.

[0011] Preferably, in step (2), the crosslinking agent is ethylene glycol dimethacrylate and the initiator is azobisisobutyronitrile, and the amount used is 0.01g.

[0012] Preferably, in step (4), the organic solvent used for Soxhlet extraction is a mixed solution of methanol and acetic acid in a volume ratio of 9:1.

[0013] Preferably, the polymer has a core-shell-shell structure, wherein For the core, The inner shell is composed of a molecularly imprinted polymer and the outer shell, and the material exhibits magnetic separation properties under an applied magnetic field.

[0014] Preferably, the polymer is used as an adsorbent for dispersion solid-phase extraction or solid-phase extraction.

[0015] Preferably, the application includes the following steps:

[0016] (a) The magnetic molecularly imprinted polymer is activated with methanol and water and then separated under an external magnetic field;

[0017] (b) Add the activated polymer to the environmental water sample and extract by shaking for 10-30 minutes;

[0018] (c) After extraction, the mixture is separated under an external magnetic field and the supernatant is discarded;

[0019] (d) Elute the adsorbed geosmin with eluent, collect the eluent, dry it with nitrogen, redissolve it, filter it, and use it for GC-MS analysis.

[0020] Preferably, the eluent is a mixed solution of methanol and acetic acid in a volume ratio of 9:1.

[0021] Preferably, the environmental water sample includes surface water, lake water, or drinking water source, and the polymer has an equilibrium adsorption capacity of not less than 5.58 mg·g⁻¹ for geosmin, with an adsorption equilibrium time not exceeding 75 minutes.

[0022] Compared with the prior art, the present invention provides a method for preparing magnetic geosmin molecularly imprinted polymers and their applications, which have the following beneficial effects:

[0023] 1. The preparation method and application of the magnetic geosmin molecularly imprinted polymer: using cis-decahydro-1-naphthol as a virtual template, specific recognition holes highly matched with geosmin molecules in spatial structure and functional groups were successfully constructed in the polymer network. This material exhibits a significantly higher adsorption capacity for geosmin than non-imprinted materials (reaching 5.58 mg / g in Example 3) and possesses excellent resistance to interference from complex matrices, enabling precise capture of target substances from coexisting substances such as dissolved organic matter and humic substances.

[0024] 2. The preparation method and application of this magnetic geosmin molecularly imprinted polymer, by constructing a... With a core-shell-shell structure featuring a magnetic core, the material of this invention can achieve rapid and thorough solid-liquid separation within 1-2 minutes under an applied magnetic field. This characteristic makes it particularly suitable for magnetic dispersion solid-phase extraction, eliminating the cumbersome steps of centrifugation, filtration, or column packing required by traditional solid-phase extraction, significantly simplifying the operation process, reducing pretreatment time from several hours to approximately 30 minutes, and greatly improving analytical efficiency.

[0025] 3. The preparation method and application of the magnetic geosmin molecularly imprinted polymer: Applying the material of this invention to the pretreatment of trace geosmin in actual water samples (such as lake water) demonstrates high spiked recoveries (92.5% - 106.3%) and good precision (RSD < 8%). This proves its excellent enrichment and purification capabilities in complex real sample matrices, effectively reducing matrix effects and significantly improving the sensitivity, accuracy, and reliability of subsequent GC-MS detection, providing strong technical support for ensuring drinking water safety. Attached Figure Description

[0026] Figure 1 The image shows the morphology of the magnetic molecularly imprinted polymer material prepared in this invention.

[0027] Figure 2 XRD pattern of magnetic molecularly imprinted polymeric material;

[0028] Figure 3 This is a thermogravimetric analysis diagram of a magnetic molecularly imprinted polymer material.

[0029] Figure 4 This is a graph showing the results of magnetic dispersion solid-phase extraction analysis of magnetic molecularly imprinted polymer materials. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Please see Figure 1-4 This invention provides a technical solution: a method for preparing a magnetic geosmin molecularly imprinted polymer and its application.

[0032] Example 1: Magnetic geosmin molecularly imprinted polymer ( Preparation of DMIP

[0033] (1) Surface functionalization Preparation:

[0034] Weigh 0.8 g of the pre-prepared Nanoparticles were dispersed in 50 mL of toluene solution and sonicated for 20 minutes. Then, 1.5 mL of silane coupling agent KH-570 was slowly added dropwise under continuous mechanical stirring. After purging with nitrogen to remove oxygen, the reaction was carried out at 70°C for 12 hours. After the reaction, solid-liquid separation was performed using a strong magnet. The resulting solid was washed three times with anhydrous ethanol and dried overnight at 60°C in a vacuum drying oven to obtain surface-modified nanoparticles. .

[0035] (2) Prepolymerization and polymerization reaction:

[0036] The template molecule cis-decahydro-1-naphthol (0.5 mmol) and the functional monomer methacrylic acid (MAA, 1.5 mmol) were dissolved in 50 mL of acetonitrile and pre-assembled by magnetic stirring at room temperature for 30 minutes. Subsequently, the modified Fe3O4@SiO2 (0.1 g) prepared in step (1), the crosslinking agent ethylene glycol dimethacrylate (EGDMA, 5 mmol), and the initiator azobisisobutyronitrile (AIBN, 0.01 g) were added to the prepolymer solution and ultrasonically dispersed for 10 minutes to form a uniform suspension. Nitrogen gas was purged into the reaction system for 15 minutes to remove oxygen, and then the system was sealed and placed in a water bath constant temperature shaker. The reaction was first carried out at 50°C for 6 hours, and then the temperature was increased to 60°C to continue the reaction for 24 hours.

[0037] (3) Separation and post-processing of products:

[0038] After the reaction was complete, a gray solid product was obtained by separation using an external magnet. The product was washed three times each with chloroform and methanol to remove unreacted monomers and impurities. The washed product was then dried under a vacuum of -0.2 MPa and at 60°C for 24 hours to obtain a grayish-white coarsely imprinted polymer.

[0039] (4) Removal of template molecules:

[0040] The crude polymer was placed in a Soxhlet extractor and extracted continuously for 48 hours using a methanol:acetic acid (9:1, v / v) mixture as the extraction solvent. The eluent was analyzed every 12 hours using gas chromatography-mass spectrometry (GC-MS) until the characteristic peak of the template molecule cis-decahydro-1-naphthol was no longer detectable, indicating complete template elution. The final product obtained was the magnetic geosmin molecularly imprinted polymer. DMIP), with a mass of 0.152 g.

[0041] Example 2: Comparative preparation of different monomer ratios

[0042] The difference between this embodiment and Example 1 is that the molar ratio of the template molecule to the functional monomer is adjusted, specifically: cis-decahydro-1-naphthol:MAA:EGDMA = 1:4:20 (molar ratio). The preparation steps are the same as in Example 1.

[0043] The obtained product was observed by scanning electron microscopy (SEM) (see [link]). Figure 1 The material exhibits a clear core-shell-shell structure, indicating the successful construction of a composite structure with Fe3O4 as the magnetic core, SiO2 as the intermediate layer, and a molecularly imprinted polymer as the outer shell. Comparative adsorption experiments revealed that the polymer exhibited the highest adsorption capacity for geosmin when the template-to-monomer ratio was 1:3 (Example 1), indicating that this ratio is the optimal choice.

[0044] Example 3: Geosmin Adsorption Performance Test

[0045] To evaluate the adsorption performance of the prepared material, static adsorption experiments were conducted:

[0046] Accurately weigh 10.0 mg of the solution prepared in Example 1. DMIP was added to 10 mL of GSM methanol solutions with different initial concentrations (1-10 mg / L). The mixtures were shaken in a constant-temperature shaker (25°C), and samples were taken at different time points. The adsorbent was rapidly separated using an external magnet, and the supernatant was used to determine the remaining GSM concentration by GC-MS.

[0047] Experimental results (see) Figure 4 )show:

[0048] The material reaches adsorption equilibrium for GSM within approximately 75 minutes, demonstrating rapid adsorption kinetics.

[0049] When the initial concentration of GSM was 8 mg / L, the equilibrium adsorption capacity of the material reached 5.58 mg / g, which is higher than that of non-magnetic imprinted polymers (~4.2 mg / g) and non-imprinted magnetic materials (~2.1 mg / g) reported in the literature.

[0050] As a control, non-imprinted polymers were tested under the same conditions ( NIP (prepared in the same manner as in Example 1 but without the addition of template molecules) exhibits an adsorption capacity of only 1.95 mg / g for GSM, indicating that the material of this invention has significant imprinting effect and specific recognition ability.

[0051] Example 4: Application of Geosmin in Real Water Samples

[0052] This embodiment will demonstrate DMIP, as a magnetic dispersion solid phase extraction (d-SPE) adsorbent, is used for the enrichment and detection of trace geosmin in actual water samples.

[0053] (1) Sample pretreatment:

[0054] Take 30 mL of lake water sample filtered through a 0.45 μm microporous membrane (stored at 4°C) and place it in a 50 mL centrifuge tube. Add 15 mg of the solution prepared in Example 1. DMIP adsorbent.

[0055] (2) Extraction and elution:

[0056] Place the centrifuge tubes in a constant temperature water bath shaker and shake for 20 minutes at room temperature for extraction. After extraction, place the centrifuge tubes on a magnetic rack; the adsorbent will be completely adsorbed onto the tube wall within 1 minute. Discard the supernatant. Add 2 mL of a methanol:acetic acid (9:1, v / v) mixture to the adsorbent and shake for 10 minutes for elution. Collect the eluent and dry it under a gentle nitrogen stream.

[0057] (3) Instrumental analysis:

[0058] The residue was redissolved in 1.0 mL of methanol, and the solution was filtered through a 0.22 μm organic filter membrane and then analyzed by GC-MS.

[0059] (4) Methodological validation:

[0060] GSM standards at low, medium, and high concentration levels (0.15, 1.0, and 3.0 μg / L) were added to water samples, with each level measured in triplicate. The intra-day precision (RSD) ranged from 0.75% to 4.32%, and the inter-day precision (RSD) ranged from 3.15% to 7.64%. The recoveries ranged from 92.5% to 106.3%. This method demonstrates that the material of this invention can effectively overcome interference from complex aquatic matrices, enabling rapid and accurate detection of trace amounts of geosmin.

[0061] in conclusion

[0062] The above embodiments fully demonstrate that the method for preparing magnetic geosmin molecularly imprinted polymers provided by the present invention is feasible and has good reproducibility. The prepared material possesses high adsorption capacity, rapid magnetic response, and excellent selective recognition ability, and can serve as a highly efficient sample pretreatment medium, significantly improving the detection efficiency and reliability of trace geosmin in water samples from complex environments, and has broad prospects for industrial application.

[0063] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a magnetic geosmin molecularly imprinted polymer, characterized by, The method comprises the following steps: (1) surface functionalized nanoparticles are reacted with silane coupling agent KH-570 in toluene solution to obtain modified nanoparticles ;​ (2) The virtual template molecule cis-decahydro-1-naphthol is dissolved in acetonitrile with a functional monomer methacrylic acid to perform a pre-polymerization reaction, and then the modified crosslinking agent ethylene glycol dimethacrylate and initiator azobisisobutyronitrile are added to perform a polymerization reaction at 50-60°C under nitrogen protection; (3) After the reaction is completed, the product is separated by an external magnetic field, washed and dried to obtain a crude product; (4) The template molecules are removed by Soxhlet extraction until no template molecules are detected by GC-MS, to obtain the magnetic geosmin molecularly imprinted polymer.

2. The method for preparing a magnetic geosmin molecularly imprinted polymer according to claim 1, characterized in that, The step (1) in the application has the following steps: The amount of the silane coupling agent KH-570 is 0.5-1 g, and the dropping is carried out under ultrasonic treatment and continuous stirring, the reaction time is 12 hours, and the reaction is carried out under nitrogen protection.

3. The method for preparing a magnetic geosmin molecularly imprinted polymer according to claim 1 and its application, characterized in that, In the step (2), the molar ratio of the virtual template molecules to the functional monomer methacrylic acid is 1:

3.

4. The method for preparing a magnetic geosmin molecularly imprinted polymer according to claim 1 and its application, characterized in that, In the step (2), the crosslinking agent is ethylene glycol dimethacrylate, and the initiator is azobisisobutyronitrile, and the amount of the initiator is 0.01 g.

5. The method for preparing a magnetic geosmin molecularly imprinted polymer according to claim 1 and its application, characterized in that, In the step (4), the organic solvent used for Soxhlet extraction is a mixed solution of methanol and acetic acid, and the volume ratio is 9:

1.

6. A magnetic geosmin molecularly imprinted polymer prepared according to the method of any one of claims 1 to 5. The polymer has a core-shell-shell structure, wherein is the core, is the inner shell, the molecularly imprinted polymer is the outer shell, and the material has magnetic separation properties under an applied magnetic field.

7. Use of the magnetic geosmin molecularly imprinted polymer according to claim 6 for selective enrichment and separation of geosmin, characterized in that, The polymer is used as an adsorbent for dispersive solid-phase extraction or solid-phase extraction.

8. Use according to claim 7, characterized in that, The application comprises the following steps: (a) The magnetic molecularly imprinted polymer is activated with methanol and water, and separated under an external magnetic field; (b) The activated polymer is added to an environmental water sample, and shaken for 10-30 minutes for extraction; (c) After the extraction is completed, the polymer is separated under an external magnetic field, and the supernatant is discarded; (d) The adsorbed geosmin is eluted with an eluent, the eluent is collected, dried with nitrogen, redissolved, filtered, and used for GC-MS analysis.

9. Use according to claim 8, characterized in that, The eluent is a mixed solution of methanol and acetic acid, and the volume ratio is 9:

1.

10. Use according to claim 7, characterized in that, The environmental water sample comprises surface water, lake water or drinking water sources, the equilibrium adsorption capacity of the polymer for geosmin is not less than 5.58 mg·g⁻¹, and the adsorption equilibrium time is not more than 75 minutes.

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