Preparation method of magnetic organic framework material and application of magnetic organic framework material to adsorption of tetrabromobisphenol A

Abstract

The invention relates to a method for ultrasonically preparing a fluorine-functionalized magnetic covalent organic framework and application of the fluorine-functionalized magnetic covalent organic framework to adsorption of tetrabromobisphenol A. The invention discloses a preparation method and application of a fluorine-functionalized magnetic covalent organic framework (Fe3O4 (at) TFAPT-TFPA (at) COF), and belongs to the technical field of adsorbent preparation and food safety detection. A fluorine functional group is modified on an amine monomer by adopting a pre-modification strategy, and then the fluorine-functionalized magnetic covalent organic framework is prepared by adopting an ultrasonic method. Taking magnetic ferroferric oxide nanoparticles as a carrier, immersing the magnetic ferroferric oxide nanoparticles into an acetonitrile solution, then adding 4, 4 ', 4' '-(1, 3, 5-triazine-2, 4, 6-triyl)-tri-(2-fluoroaniline), tri-(4-formyl phenyl)-amine and glacial acetic acid, and carrying out a reaction under an ultrasonic condition to obtain the fluorine-functionalized magnetic covalent organic framework material. The magnetic covalent organic framework is applied to a small separation column, and real-time removal of tetrabromobisphenol A is achieved.

Description

Technical Field

[0001] The invention relates to a preparation method of a magnetic organic framework material and its application in adsorbing tetrabromobisphenol A, belonging to the technical field of composite material preparation and food safety detection. Background Art

[0002] Tetrabromobisphenol A (TBBPA) is the world's largest-produced brominated flame retardant, widely used in the production of electronic products and polymer materials such as plastics. Tetrabromobisphenol A is a persistent organic pollutant that is used in large quantities and widely exists in the environment. It has long-term residual, bioaccumulative, semi-volatile, highly toxic, carcinogenic, teratogenic and mutagenic properties in the environment. It can migrate long distances in the atmosphere and can be deposited back to the earth, causing pollution of environmental media such as the atmosphere, water bodies, sediments and soil, and related ecosystems.

[0003] Magnetic covalent organic framework (MCOFs) composites are a new type of functional materials. They have the characteristics of strong magnetic properties of magnetic materials that are conducive to separation and recovery, and the characteristics of COFs such as large specific surface area, high porosity, precise molecular structure and adjustable pore size. They have attracted widespread attention in recent years. According to the composition and function of magnetic covalent organic framework materials, the reported MCOFs can be roughly divided into three categories: the first category is the original MCOFs composed of nanoparticles and COFs 2 components, with a typical structure of core@shell, and the core is generally a magnetic nanoparticle, such as Fe 3 O 4 and functionalized magnetic nanoparticles, the outer shell is a COFs layer with a porous structure. The second type is functionalized MCOFs composed of three or more components: magnetic nanoparticles, COFs and other substances (such as carbon nanotubes, graphene, β-cyclodextrin, etc.). The third type is mainly composed of iron, cobalt, nickel and their alloys and COFs. Its structure is mainly that magnetic metal and its alloy nanoparticles are embedded or dispersed in COFs to produce low-density organic-inorganic nanomagnets, thus obtaining a low-density magnetic nanocomposite material with good dispersibility.

[0004] Magnetic adsorbents are crucial in the magnetic solid phase extraction process, and the advantages of MCOFs are high specific surface area, good chemical and thermal stability, high adsorption capacity, good magnetic response, and high reusability. Therefore, MCOF is of great significance for the effective removal of tetrabromobisphenol A in food samples. Summary of the invention

[0005] The invention aims to provide a method for ultrasonically preparing a magnetic covalent organic framework and its application in adsorbing tetrabromobisphenol A.

[0006] For the above purpose, the main technical solutions adopted by the present invention include: A method for ultrasonically preparing a magnetic covalent organic framework comprises the following steps: (1) Magnetic Fe 3 O 4 Preparation of nanospheres Add FeSO into a round bottom flask 4 ∙7H 2 O and FeCl 3 ∙6H 2 O, then add deionized water. Under the protection of high-purity nitrogen, the above solution is continuously stirred. After complete dissolution, the coprecipitant NH 3 ·H 2 O, and stirred continuously at 50 °C. Afterwards, the black product was collected with a strong magnet and washed five times with deionized water. 3 O 4 Vacuum dry.

[0007] (2) Preparation of 4, 4', 4''-(1,3,5-triazine-2,4,6-triyl)-tris-(2-fluoroaniline) Add 3-fluoro-4-aminobenzonitrile to a round-bottom flask at 0°C, then drop trifluoromethanesulfonic acid under an inert gas environment and stir at room temperature for 24 hours. After the reaction is complete, add distilled water and neutralize with NaOH solution to pH = 7. Finally, filter the obtained yellow product, wash it with methanol and distilled water several times, and air dry it for later use.

[0008] (3) Fluorine-functionalized magnetic covalent organic framework materials (Fe 3 O 4 Preparation of @TFAPT-TFPA@COF Fe 3 O 4 Add acetonitrile and sonicate. After dissolution, add 4, 4', 4''-(1,3,5-triazine-2,4,6-triyl)-tri-(2-fluoroaniline) and continue sonication for 20 minutes. Then add tri-(4-formylphenyl)-amine and glacial acetic acid. Then, sonicate the mixed solution. Finally, wash the product with methanol and tetrahydrofuran until the supernatant is colorless and dry for later use.

[0009] The present invention also provides the application of the magnetic covalent organic framework material to adsorb tetrabromobisphenol A in water, which can effectively adsorb tetrabromobisphenol A in water and has the advantages of good stability, large adsorption capacity, and easy separation from water. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 The fluorine-functionalized magnetic covalent organic framework (Fe 3 O 4 Schematic diagram of the structure of @TFAPT-TFPA@COF).

[0011] Figure 2 The Fe prepared in Example 1 3 O 4 and Fe 3 O 4 SEM and TEM spectra of @TFAPT-TFPA@COF.

[0012] Figure 3 The Fe prepared in Example 1 3 O 4 , TFAPT, TFPA and Fe 3 O 4 Infrared spectrum of @TFAPT-TFPA@COF.

[0013] Figure 4 The Fe prepared in Example 1 3 O 4 BET spectrum of @TFAPT-TFPA@COF.

[0014] Figure 5 The Fe prepared in Example 1 3 O 4 and Fe 3 O 4 XRD pattern of @TFAPT-TFPA@COF.

[0015] Figure 6 The Fe prepared in Example 1 3 O 4 XPS spectrum of @TFAPT-TFPA@COF.

[0016] Figure 7 The Fe prepared in Example 1 3 O 4 and Fe 3 O 4 VSM spectrum of @TFAPT-TFPA@COF.

[0017] Figure 8 The Fe prepared in Example 1 3 O 4 @TFAPT-TFPA@COF separation of tetrabromobisphenol A in water.

[0018] Fig. 9 The Fe prepared in Example 1 3 O 4 @TFAPT-TFPA@COF loaded separation column to separate tetrabromobisphenol A in water. Implementation

[0019] In order to better explain the present invention and facilitate understanding, the present invention is described in detail below through specific implementation modes in conjunction with the accompanying drawings.

[0020] Example 1 Fluorine-functionalized magnetic covalent organic framework Fe 3 O 4 The preparation of @TFAPT-TFPA@COF includes the following steps: (1) Magnetic Fe 3 O 4 Preparation of nanospheres Add 2.8082 g FeSO into the flask. 4 ∙7H 2 O and 5.4606 g FeCl 3 ∙6H 2 O, then add deionized water. Under the protection of high-purity nitrogen, the above solution is continuously stirred. After complete dissolution, the coprecipitant NH 3 ·H 2 O (1 mol L -1） , stirring continuously at 50 °C. Afterwards, the black product was collected with a strong magnet and washed five times with deionized water. 3 O 4 Dry in vacuum at 70 °C for 6 h.

[0021] (2) Preparation of 4, 4', 4''-(1,3,5-triazine-2,4,6-triyl)-tris-(2-fluoroaniline) Add 500 mg, 3.8 mmol 3-fluoro-4-aminobenzonitrile to a round-bottom flask at 0°C, then drop 2 mL trifluoromethanesulfonic acid under an inert gas environment and stir at room temperature for 24 h. After the reaction is complete, add 20 mL distilled water and neutralize with 2 mol / L NaOH solution to pH = 7. Finally, filter the obtained yellow product, wash it with methanol and distilled water several times, and vacuum dry it at 70°C for 6 hours for later use.

[0022] (3) Fluorine-functionalized magnetic covalent organic framework materials (Fe 3 O 4 Preparation of @TFAPT-TFPA@COF 40 mgFe 3 O 4 Add 6 mL of acetonitrile and sonicate. After dissolution, add 56 mg of 4, 4', 4''-(1,3,5-triazine-2,4,6-triyl)-tris-(2-fluoroaniline) and continue sonication for 20 minutes. Then add 33 mg of tris-(4-formylphenyl)-amine and 12 mol L -1Then, the mixed solution was ultrasonically treated for two hours. Finally, the product was washed with methanol and tetrahydrofuran until the supernatant was colorless and vacuum dried at 70°C for 6 hours for use.

[0023] (4) Magnetic covalent organic framework Fe 3 O 4 The synthetic route of @TFAPT-TFPA@COF is as follows Figure 1 shown.

[0024] Example 2 Fluorine-functionalized magnetic covalent organic framework Fe 3 O 4 Characterization of @TFAPT-TFPA@COF (1) Using transmission electron microscopy and scanning electron microscopy to study the Fe 3 O 4 Fluorine-functionalized magnetic covalent organic framework Fe 3 O 4 The morphology of @TFAPT-TFPA@COF was characterized, such as Figure 2 As shown in a, Fe 3 O 4 The nanoparticles are spherical and about 10-20 nm in size. Figure 2 As shown in b, Fe 3 O 4 @TFAPT-TFPA@COF becomes rougher, indicating that TFAPT-TFPA@COF is successfully wrapped in Fe 3 O 4 Nanoparticle surface. Figure 2 As shown in c, the SEM image shows that Fe 3 O 4 The size of @TFAPT-TFPA@COF is about 300 nm, which indirectly proves that TFAPT-TFPA@COF is successfully encapsulated in Fe 3 O 4 Nanoparticle surface.

[0025] (2) Fourier transform infrared spectroscopy was used to analyze the Fe 3 O 4 , TFAPT, TFPA and fluorine-functionalized magnetic covalent organic frameworks Fe 3 O 4 The structure of @TFAPT-TFPA@COF was characterized, such as Figure 3 As shown. 632 cm -1 Corresponding to Fe 3 O 4 Fe-O stretching vibration peaks. 1360, 1500, 3320 cm -1 The peaks at 1699 cm correspond to the CN and NH stretching vibrations of TFAPT.-1 The corresponding peak is the CO stretching vibration peak of TFPA. 3 O 4 @TFAPT-TFPA@COF at 1580 cm -1 The C=N characteristic peak appeared at , while the CN and NH stretching vibration peaks disappeared. These results indicate that the COF shell was successfully synthesized.

[0026] (3) Using BET to characterize the fluorine-functionalized magnetic covalent organic framework Fe 3 O 4 The specific surface area and pore volume of @TFAPT-TFPA@COF were characterized, such as Figure 4 As shown. 3 O 4 The specific surface area and pore volume of @TFAPT-TFPA@COF are 117.32 m 2 g -1 and 0.17 cm³ g -1 . After testing, Fe 3 O 4 The pore size of @TFAPT-TFPA@COF is about 2.72 nm.

[0027] (4) X-ray diffractometer was used to analyze the Fe 3 O 4 Fluorine-functionalized magnetic covalent organic framework Fe 3 O 4 The crystallinity and stability of @TFAPT-TFPA@COF were characterized, as Figure 5 As shown. 3 O 4 The diffraction peaks measured in @TFAPT-TFPA@COF are 30.1°, 35.5°, 43.1°, 53.6°, 57.2° and 62.6°, corresponding to Fe 3 O 4 (200), (311), (400), (422), (511), (440) crystal planes. 3 O 4 @TFAPT-TFPA@COF has no impurity peaks in XRD, indicating that the prepared Fe 3 O 4 @TFAPT-TFPA@COF has good crystallinity and phase purity.

[0028] (5) XPS analysis of the fluorine-functionalized magnetic covalent organic framework Fe 3 O 4 The chemical composition of @TFAPT-TFPA@COF was characterized, such as Figure 6 As shown.3 O 4 The spectrum of @TFAPT-TFPA@COF shows binding energies of 285, 399, 530, 711, and 686 eV, belonging to C 1s, N 1s, O 1s, Fe 2p, and F 1s, respectively. Figure 7 The peaks at 710.9 and 724.4 eV belong to Fe2p 3 / 2 and Fe 2p 1 / 2 These results confirm that Fe 3 O 4 Successful formation of @TAFPT-TFPA@COF covalently bonded nanocomposite.

[0029] (6) Using VSM to measure Fe 3 O 4 and magnetic covalent organic framework Fe 3 O 4 The magnetic response properties of @TFAPT-TFPA@COF were characterized, such as Figure 7 As shown. 3 O 4 and Fe 3 O 4 The hysteresis strengths of @TFAPT-TFPA@COF are 69.4 emu g -1 and 17.8 emu g -1 , which indirectly indicates that Fe 3 O 4 Successfully wrapped by TFAPT-TFPA@COF.

[0030] Example 3 Fluorine-functionalized magnetic covalent organic framework (Fe 3 O 4 @TFAPT-TFPA@COF) (1) 30 mg Fe 3 O 4 @TFAPT-TFPA@COF was loaded into a 1 mL cartridge and then spiked with 100 mg / L -1 The sample solution of tetrabromobisphenol A was passed through. Finally, HPLC analysis was performed.

[0031] (2) Experimental results are as follows Figure 8 and 9 shown.

[0032] (3) Result analysis: Figure 8 and 9 It can be concluded that after the adsorption process is completed, the residual concentration of tetrabromobisphenol A is 0.0021 mg / L, which is lower than 0.0500 mg / L, indicating that Fe 3 O 4@TFAPT-TFPA@COF has a strong removal ability for tetrabromobisphenol A in urban water and has certain practical application potential.

[0033] The above is only a preferred embodiment of the present invention, and does not limit the present invention in other forms. Any person skilled in the art can use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention still belongs to the protection scope of the technical solution of the present invention.

Claims

1. Method for preparing magnetic covalent organic framework materials by ultrasound, It is characterized in that The following steps are involved: (1) Magnetic Fe 3 O 4 Preparation of nanospheres Add FeSO into a round bottom flask 4 ∙7H 2 O and FeCl 3 ∙6H 2 O, then add deionized water. Under the protection of high-purity nitrogen, the above solution is continuously stirred. After complete dissolution, the coprecipitant NH 3 ·H 2 O, and stirred continuously at 50 °C. Afterwards, the black product was collected with a strong magnet and washed five times with deionized water. 3 O 4 Vacuum drying; (2) Preparation of 4, 4', 4''-(1,3,5-triazine-2,4,6-triyl)-tris-(2-fluoroaniline) Add 3-fluoro-4-aminobenzonitrile to a round-bottom flask at 0°C, then drop trifluoromethanesulfonic acid under an inert gas environment and stir at room temperature for 24 hours. After the reaction is complete, add distilled water and neutralize with NaOH solution to pH = 7. Finally, filter the obtained yellow product, wash it with methanol and distilled water several times, and air dry it for later use; (3) Fluorine-functionalized magnetic covalent organic framework materials (Fe 3 O 4 Preparation of @TFAPT-TFPA@COF Fe 3 O 4 Add acetonitrile and sonicate. After dissolution, add 4, 4', 4''-(1,3,5-triazine-2,4,6-triyl)-tri-(2-fluoroaniline) and continue sonication for 20 minutes. Then add tri-(4-formylphenyl)-amine and glacial acetic acid. Then, sonicate the mixed solution. Finally, wash the product with methanol and tetrahydrofuran until the supernatant is colorless and dry for later use.

2. The use according to claim 1, It is characterized in that In step (1), the FeSO 4 ∙7H 2 O and FeCl 3 ∙6H 2 The added amounts of O were 2.8082 g and 5.4606 g, respectively. 3 ·H 2 The concentration of O is 1 mol L -1 The drying temperature was 70°C and the drying time was 6 hours.

3. The use according to claim 1, It is characterized in that In step (2), the amount of 3-fluoro-4-aminobenzonitrile added is 500 mg (3.8 mmol). The amount of trifluoromethanesulfonic acid added is 2 mL. The amount of distilled water added is 20 mL. The concentration of NaOH is 2 mol / L. The drying temperature is 70°C and the drying time is 6 hours.

4. The use according to claim 1, It is characterized in that In step (3), the Fe 3 O 4 The amount added was 40 mg. The amount of acetonitrile added was 6 mL. The amount of 4, 4', 4''-(1,3,5-triazine-2,4,6-triyl)-tris-(2-fluoroaniline) added was 56 mg. The amount of tris-(4-formylphenyl)-amine added was 33 mg. The concentration of glacial acetic acid added was 12 mol / L. The ultrasonic treatment time was 2 hours. The drying temperature was 70°C and the drying time was 6 hours.

5. A fluorine-functionalized magnetic covalent organic framework (Fe 3 O 4 @TFAPT-TFPA@COF) in the adsorption and removal of tetrabromobisphenol A. It is characterized in that The following steps are involved: (1) Prepare Fe 3 O 4 @TFAPT-TFPA@COF was loaded into a 1 mL column, and then a sample solution containing a certain concentration of tetrabromobisphenol A was passed through; (2) The samples to be tested are detected and analyzed by high performance liquid chromatography.

6. The use according to claim 5, It is characterized in that In step (1), the Fe 3 O 4 The addition amount of @TFAPT-TFPA@COF was 30 mg, and the spiked concentration was 100 mg L -1 .

7. The use according to claim 5, It is characterized in that In step (2), the conditions for the high performance liquid chromatography analysis are as follows: Waters Alliance HPLC system (Waters Corporation, Milford, MA 01757, USA) equipped with a 2489 detector and an Atiantis T3 (250 × 4.6 mm, 5µm) chromatographic column. The column temperature is 25°C, and the injection volume is 20 μL. The mobile phase is methanol (A) and water (B): 0 min, 60% A; 20 min, 80% A, and the detection wavelength of tetrabromobisphenol A is 280 nm.

Images