A magnetic nanoparticle-modified polymer monolithic column, a preparation method and applications thereof

Abstract

The application belongs to the technical field of functional polymer materials, and particularly relates to a magnetic nanoparticle modified polymer monolithic column, a preparation method and application. The monolithic column is prepared by an in-situ thermal initiation polymerization method, styrene is used as a functional monomer, divinylbenzene is used as a crosslinking agent, dodecanol and toluene are used as binary pore-forming agents, azobisisobutyronitrile is used as an initiator, and Fe3O4 / SiO2 composite nanoparticles are added, and the magnetic nanoparticle modified polymer monolithic column is prepared through a polymerization reaction. The preparation method is simple, easy to operate and mild in reaction conditions, the prepared monolithic column is uniform in structure, good in permeability and large in specific surface area, and has good separation performance. As a separation medium, the prepared monolithic column is combined with a USB4000 optical fiber spectrometer by using high-frequency electromagnetic induction heating technology, a new online detection method of benzene series is established, the application range of the monolithic column is expanded, and a novel idea is provided for chromatographic separation and detection technology.

Description

Technical Field

[0001] This invention belongs to the field of functional polymer materials technology, specifically relating to a polymer monolithic column modified with magnetic nanoparticles, its preparation method, and its application. Background Technology

[0002] Gas chromatography, with its advantages of high separation efficiency, fast analysis speed, high selectivity, and small sample volume, has become a mature and widely used separation and analysis method. However, as the core component of the chromatographic system, the performance of the chromatographic column directly determines the separation effect.

[0003] Monolithic columns, also known as continuous beds, have attracted widespread attention from researchers in the field of separation science since their emergence in the 1990s. Compared with traditional packed columns, monolithic columns have advantages such as simple preparation methods, fast mass transfer rates, high permeability, low back pressure, easy surface modification, rich chemoselectivity, porous structure, and large specific surface area. Based on matrix properties, monolithic columns can be classified into three categories: organic polymer monolithic columns, silica monolithic columns, and organic-silica hybrid monolithic columns. Among them, organic polymer monolithic columns have received increasing attention in recent years due to their simple preparation methods, wide range of media selection, broad applicable pH range, and good biocompatibility.

[0004] However, the application of monolithic polymer columns in gas chromatography remains relatively limited. How to further expand the application range of monolithic polymer columns and improve their separation performance and detection sensitivity are urgent technical problems to be solved in this field. Furthermore, traditional heating methods suffer from drawbacks such as low heat transfer efficiency, inaccurate temperature control, and uneven heating, which limit the application of monolithic columns in online analysis.

[0005] Electromagnetic induction heating (EMIH) is a technology that uses the principle of electromagnetic induction to generate eddy currents inside the material being heated, thereby achieving self-heating. It has advantages such as high heat utilization rate, easy temperature control, and rapid and uniform heating, and can overcome many shortcomings of traditional heat transfer heating modes.

[0006] Based on this, the present invention proposes to introduce magnetic nanoparticles into the preparation of polymer monolithic columns, so that the monolithic columns have electromagnetic induction heating capabilities, and to combine them with spectroscopic detection technology to establish a novel online separation and detection method. Summary of the Invention

[0007] The purpose of this invention is to provide a polymer monolithic column modified with magnetic nanoparticles and its preparation method, which solves the problems of existing polymer monolithic columns in gas chromatography applications, such as limited functionality, low heating efficiency, and difficulty in achieving uniform heating.

[0008] Furthermore, by combining the prepared monolithic column with electromagnetic induction heating technology and spectral detection technology, a new method for online detection of benzene series compounds was established to expand the application range of the monolithic column.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for preparing a polymer monolithic column modified with magnetic nanoparticles includes the following steps: Step 1: Mix the functional monomer, crosslinking agent, porogen, initiator and magnetic nanoparticles to obtain a polymerization solution; Step 2: Inject the polymerization solution into the pre-activated quartz tube, seal both ends, and place it in a constant temperature chamber to heat and initiate the in-situ polymerization reaction; Step 3: After the in-situ polymerization reaction is completed, the polymer is washed and dried to obtain a monolithic column modified with magnetic nanoparticles. The magnetic nanoparticles include Fe3O4 / SiO2 composite nanoparticles.

[0010] Preferably, the contents of each component by weight are: 40-60 parts of functional monomer, 10-30 parts of crosslinking agent, 50-70 parts of pore-forming agent, 1-3 parts of initiator, and 45-55 parts of magnetic nanoparticles.

[0011] Preferably, the functional monomer includes styrene; The crosslinking agent includes divinylbenzene; The porogen includes a binary porogen composed of dodecyl alcohol and toluene; The initiator includes azobisisobutyronitrile.

[0012] Preferably, in the binary porogen, the mass ratio of dodecanol to toluene is 13:2.

[0013] Preferably, the Fe3O4 / SiO2 composite nanoparticles are prepared by the following steps: Fe3O4 nanoparticles were dispersed in ethanol, oleic acid was added as a dispersant, and after ultrasonic dispersion, tetraethyl orthosilicate and ammonia were added. After the reaction was completed, magnetic separation, washing and drying were performed to obtain Fe3O4 / SiO2 composite nanoparticles. The mass ratio of Fe3O4 nanoparticles, oleic acid, tetraethyl orthosilicate, and ammonia is (4-6):(0.2-0.4):(3-4.4):(1-2.6). The reaction conditions are stirring at 50-70℃ for 2-4 hours, and the amount of ethanol used is 60-100 times the mass of Fe3O4 nanoparticles.

[0014] Preferably, the pre-activation treatment of the quartz tube includes: S1. The quartz tube is rinsed in sequence with acetone, deionized water, sodium hydroxide aqueous solution, deionized water, hydrochloric acid solution, deionized water, and ethanol, and then dried to obtain the washed quartz tube. S2. Inject an acetone solution of 3-(trimethoxysilyl)propyl methacrylate into the washed quartz tube, seal it, and heat it to react. After the reaction is complete, rinse and dry it. The pre-activation treatment of the quartz tube is complete.

[0015] Preferably, the preparation of the polymerization liquid includes: first ultrasonically mixing the functional monomer, crosslinking agent, pore-forming agent and initiator, then adding magnetic nanoparticles, continuing ultrasonic mixing, and then purging with an inert gas to replace dissolved oxygen to obtain the polymerization liquid.

[0016] Preferably, the in-situ polymerization reaction is carried out at a temperature of 65-75°C for 20-30 hours.

[0017] The present invention also discloses a method for preparing a polymer monolithic column modified with magnetic nanoparticles as described above.

[0018] Application of a polymer monolithic column modified with magnetic nanoparticles as described above in the online detection of benzene compounds.

[0019] Compared with the prior art, the beneficial effects of the present invention are as follows: The magnetic nanoparticle-modified polymer monolithic column prepared by this invention uses styrene as a functional monomer and divinylbenzene as a crosslinking agent to form a copolymer matrix. It has a unique porous structure, large specific surface area and good permeability, which can effectively improve the mass transfer efficiency, enrichment efficiency and extraction speed of the target analyte, while using very little solvent. This invention uses SiO2-coated Fe3O4 composite nanoparticles as magnetic nanoparticles, which improves the dispersibility of magnetic particles in polymer solutions and enables the magnetic nanoparticles to be uniformly distributed in the monolithic column. This not only enables the monolithic column to have electromagnetic induction heating capability, but also ensures that the monolithic column can be uniformly heated under electromagnetic induction, providing a technical basis for subsequent online detection. This invention combines a monolithic column with electromagnetic induction heating technology to achieve the online separation process of the target object. The induction heating medium used is magnetic nanoparticles uniformly distributed in the monolithic column, which has high eddy current thermal efficiency, rapid and uniform heating, and easy temperature control, thus overcoming many shortcomings of traditional heat transfer heating modes. This invention introduces the separated target components directly into a USB4000 fiber optic spectrometer for detection, establishing a highly sensitive online automated method for detecting benzene series compounds, further improving the level of automation in the experiment, and providing a new approach for the application of monolithic columns in gas chromatography analysis; The preparation method provided by this invention is characterized by simple operation, mild reaction conditions, and low cost. The resulting material has a controllable overall structure, long service life, good reproducibility, and excellent separation performance. Attached Figure Description

[0020] Figure 1 This is a scanning electron microscope image of the polymer monolithic column obtained in Example 3 of the present invention; Figure 2 This is a transmission electron microscope image of the polymer monolithic column obtained in Example 3 of the present invention; Figure 3 The chromatogram shows the separation effect of the polymer monolithic column prepared in Example 3 of this invention on benzene series compounds. Detailed Implementation

[0021] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0022] Example 1 This embodiment discloses a method for preparing a polymer monolithic column modified with magnetic nanoparticles, comprising the following steps: Step 1: Weigh out 40 parts styrene, 10 parts divinylbenzene, 1 part azobisisobutyronitrile, and 50 parts a mixture of dodecanol and toluene (mass ratio of dodecanol to toluene is 13:2) by weight. After ultrasonic mixing at room temperature for 10 min, add 45 parts Fe3O4 / SiO2 composite nanoparticles and continue ultrasonic mixing for 10 min to uniformly disperse the nanoparticles. Purge with argon gas for 5 min to replace dissolved oxygen to obtain the polymerization solution. The Fe3O4 / SiO2 composite nanoparticles are prepared by the following steps: Fe3O4 nanoparticles were dispersed in ethanol, oleic acid was added as a dispersant, and after ultrasonic dispersion, tetraethyl orthosilicate and 28wt% ammonia were added. The mixture was stirred at 60℃ for 3h. After the reaction was completed, the nanoparticles were magnetically separated, washed, and dried to obtain Fe3O4 / SiO2 composite nanoparticles. The mass ratio of Fe3O4 nanoparticles, oleic acid, tetraethyl orthosilicate, and 28wt% ammonia is 5:0.3:3.7:1.8. The amount of ethanol used is 80 times the mass of the Fe3O4 nanoparticles; Step 2: Inject the polymerization solution into the pre-activated quartz tube, seal both ends, and place it in a constant temperature chamber. Heat the tube to initiate the in-situ polymerization reaction. The conditions for the in-situ polymerization reaction are: react at 65℃ for 30 hours. The pre-activation treatment of the quartz tube includes: S1. The quartz tube (inner diameter 0.53 mm, outer diameter 0.68 mm) is rinsed sequentially with acetone, deionized water, 0.2 M sodium hydroxide aqueous solution, deionized water, 0.2 M hydrochloric acid solution, deionized water, and ethanol. After each rinse, it is dried with argon gas to obtain the washed quartz tube. A 30wt% acetone solution of 3-(trimethoxysilyl)propyl methacrylate was injected into a washed quartz tube, both ends were sealed, and the tube was heated to react. The reaction conditions were 70°C for 12 hours. After the reaction was completed, the unreacted reagent in the quartz tube was rinsed out with ethanol, and the quartz tube was dried with argon gas. The pre-activation treatment of the quartz tube was completed. Step 3: After the in-situ polymerization reaction is completed, the quartz tube is cleaned with ethanol to remove unreacted raw materials. The quartz tube is then placed in a vacuum drying oven at 60°C and dried to constant weight to obtain a polymer monolithic column modified with magnetic nanoparticles.

[0023] Example 2 This embodiment discloses a method for preparing a polymer monolithic column modified with magnetic nanoparticles, comprising the following steps: Step 1: Weigh out 60 parts of styrene, 30 parts of divinylbenzene, 3 parts of azobisisobutyronitrile, and 70 parts of a mixture of dodecanol and toluene (mass ratio of dodecanol to toluene is 13:2) by weight. After ultrasonic mixing at room temperature for 10 min, add 55 parts of Fe3O4 / SiO2 composite nanoparticles and continue ultrasonic mixing for 10 min to uniformly disperse the nanoparticles. Purge with argon gas for 5 min to replace dissolved oxygen to obtain the polymerization solution. The preparation method of the Fe3O4 / SiO2 composite nanoparticles is the same as in Example 1; Step 2: Inject the polymerization solution into the pre-activated quartz tube, seal both ends, and place it in a constant temperature chamber. Heat the tube to initiate the in-situ polymerization reaction. The conditions for the in-situ polymerization reaction are: react at 75°C for 20 hours. The pre-activation treatment of the quartz tube is the same as in Example 1; Step 3: After the polymerization reaction is complete, the quartz tube is cleaned with ethanol to remove unreacted raw materials. The quartz tube is then dried in a vacuum drying oven at 60°C until constant weight is achieved, resulting in a polymer monolithic column modified with magnetic nanoparticles.

[0024] Example 3 This embodiment discloses a method for preparing a polymer monolithic column modified with magnetic nanoparticles, comprising the following steps: Step 1: Weigh out 50 parts styrene, 20 parts divinylbenzene, 2 parts azobisisobutyronitrile, and 60 parts of a mixture of dodecanol and toluene (mass ratio of dodecanol to toluene is 13:2) by weight. After ultrasonic mixing at room temperature for 10 min, add 50 parts Fe3O4 / SiO2 composite nanoparticles and continue ultrasonic mixing for 10 min to uniformly disperse the nanoparticles. Purge with argon gas for 5 min to replace dissolved oxygen to obtain the polymerization solution. The preparation method of the Fe3O4 / SiO2 composite nanoparticles is the same as in Example 1; Step 2: Inject the polymerization solution into the pre-activated quartz tube, seal both ends, and place it in a constant temperature chamber. Heat the tube to initiate the in-situ polymerization reaction. The conditions for the in-situ polymerization reaction are: react at 70°C for 24 hours. The pre-activation treatment of the quartz tube is the same as in Example 1; Step 3: After the polymerization reaction is complete, the quartz tube is cleaned with ethanol to remove unreacted raw materials. The quartz tube is then dried in a vacuum drying oven at 60°C until constant weight is achieved, resulting in a polymer monolithic column modified with magnetic nanoparticles.

[0025] Test example: (1) The microstructure of the polymer monolithic column modified with magnetic nanoparticles prepared in Example 3 was observed by scanning electron microscopy (SEM). The results are as follows: Figure 1 As shown. From Figure 1 It can be seen that the polymer monolithic column has a continuous and interconnected pore structure, and the polymer monolithic column skeleton is uniform with relatively uniform large pores, which makes the polymer monolithic column have relatively good permeability.

[0026] (2) The microstructure of the polymer monolithic column modified with magnetic nanoparticles prepared in Example 3 was observed by transmission electron microscopy (TEM), and the results are as follows: Figure 2 As shown. From Figure 2 It can be seen that the magnetic nanoparticles are distributed relatively evenly in the polymer, and the entire column can be heated evenly under the action of electromagnetic induction.

[0027] (3) Using the polymer monolithic column modified with magnetic nanoparticles prepared in Example 3 as the separation medium, a high-frequency electromagnetic induction heating method was employed in conjunction with a Marine Optics USB4000 fiber optic spectrometer for enrichment analysis of benzene series compounds. An ultraviolet detector was used with a detection wavelength of 273 nm, a column temperature of 230 °C, and a high-frequency electromagnetic induction heating method with a current of 0.61 A. The mixture of benzene, toluene, ethylbenzene, p / m-xylene, and o-xylene achieved highly efficient and selective separation on the polymer monolithic column modified with nanoparticles prepared in Example 3. The chromatographic separation chromatogram is shown below. Figure 3 As shown, the peaks in the chromatogram are, in order: 1: benzene, 2: toluene, 3: ethylbenzene, 4 and 5: p- / m-xylene, 6: o-xylene;Figure 3 It can be seen that the polymer monolithic column modified with magnetic nanoparticles prepared in Example 3 has a good separation effect on benzene series compounds, a high enrichment efficiency, and no obvious matrix effect.

[0028] 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 polymer monolithic column modified with magnetic nanoparticles, characterized in that, Includes the following steps: Step 1: Mix the functional monomer, crosslinking agent, porogen, initiator and magnetic nanoparticles to obtain a polymerization solution; Step 2: Inject the polymerization solution into the pre-activated quartz tube, seal both ends, and place it in a constant temperature chamber to heat and initiate the in-situ polymerization reaction; Step 3: After the in-situ polymerization reaction is completed, the polymer is washed and dried to obtain a monolithic column modified with magnetic nanoparticles. The magnetic nanoparticles include Fe3O4 / SiO2 composite nanoparticles.

2. The method for preparing a polymer monolithic column modified with magnetic nanoparticles according to claim 1, characterized in that, The contents of each component by weight are as follows: 40-60 parts of functional monomer, 10-30 parts of crosslinking agent, 50-70 parts of porogen, 1-3 parts of initiator, and 45-55 parts of magnetic nanoparticles.

3. The method for preparing a polymer monolithic column modified with magnetic nanoparticles according to claim 1, characterized in that, The functional monomer includes styrene; The crosslinking agent includes divinylbenzene; The porogen includes a binary porogen composed of dodecyl alcohol and toluene; The initiator includes azobisisobutyronitrile.

4. The method for preparing a polymer monolithic column modified with magnetic nanoparticles according to claim 3, characterized in that, In the binary porogen, the mass ratio of dodecanol to toluene is 13:

2.

5. The method for preparing a polymer monolithic column modified with magnetic nanoparticles according to claim 1, characterized in that, The Fe3O4 / SiO2 composite nanoparticles are prepared by the following steps: Fe3O4 nanoparticles were dispersed in ethanol, oleic acid was added as a dispersant, and after ultrasonic dispersion, tetraethyl orthosilicate and ammonia were added. After the reaction was completed, magnetic separation, washing and drying were performed to obtain Fe3O4 / SiO2 composite nanoparticles. The mass ratio of Fe3O4 nanoparticles, oleic acid, tetraethyl orthosilicate, and ammonia is (4-6):(0.2-0.4):(3-4.4):(1-2.6). The reaction conditions are stirring at 50-70℃ for 2-4 hours, and the amount of ethanol used is 60-100 times the mass of Fe3O4 nanoparticles.

6. The method for preparing a polymer monolithic column modified with magnetic nanoparticles according to claim 1, characterized in that, The pre-activation treatment of the quartz tube includes: S1. The quartz tube is rinsed in sequence with acetone, deionized water, sodium hydroxide aqueous solution, deionized water, hydrochloric acid solution, deionized water, and ethanol, and then dried to obtain the washed quartz tube. S2. Inject an acetone solution of 3-(trimethoxysilyl)propyl methacrylate into the washed quartz tube, seal it, and heat it to react. After the reaction is complete, rinse and dry it. The pre-activation treatment of the quartz tube is complete.

7. The method for preparing a polymer monolithic column modified with magnetic nanoparticles according to claim 1, characterized in that, The preparation of the polymerization liquid includes: first, ultrasonically mixing the functional monomer, crosslinking agent, pore-forming agent and initiator, then adding magnetic nanoparticles, continuing ultrasonic mixing, and then purging with inert gas to replace dissolved oxygen to obtain the polymerization liquid.

8. The method for preparing a polymer monolithic column modified with magnetic nanoparticles according to claim 1, characterized in that, The conditions for the in-situ polymerization reaction are: reaction at 65-75℃ for 20-30 hours.

9. A polymer monolithic column modified with magnetic nanoparticles prepared by the method described in any one of claims 1-8.

10. The application of a polymer monolithic column modified with magnetic nanoparticles as described in claim 9 in the online detection of benzene compounds.

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