Magnetic covalent organic framework nano material, preparation method and application

A covalent organic framework and nanomaterial technology, applied in the field of magnetic covalent organic framework nanomaterials and preparation, can solve problems such as human health risks, achieve excellent magnetic separation characteristics, simple and convenient operation, and high adsorption capacity

Active Publication Date: 2022-04-29

NORTHWEST UNIV

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(2) pretreatment of sample to be tested: the liquor sample of different fragrance type is diluted w...

Abstract

The invention discloses a magnetic covalent organic framework nano-material, a preparation method and application, firstly, magnetic Fe3O4 nano-particles are prepared, then the magnetic Fe3O4 nano-particles and a 2, 5-dihydroxy terephthalaldehyde solution are mixed, stirring is conducted for 1-3 h at the temperature of 30-65 DEG C, and Fe3O4 nano-particles modified for the first time are obtained; and mixing the Fe3O4 nanoparticles modified for the first time, 1, 3, 5-tris (4-aminophenyl) benzene and 2, 5-dihydroxy terephthalaldehyde in the most week, adding an acetic acid solution, and stirring and reacting at room temperature to obtain the magnetic covalent organic framework nano material Fe3O4 (at) COFs. The magnetic covalent organic framework nano-material prepared by the invention not only has the excellent properties of large specific surface area, rich adsorption sites and the like of a covalent organic framework, but also inherits the excellent magnetic separation characteristic of a magnetic material, so that the composite material has the characteristics of high adsorption and separation speed and high adsorption capacity, can be repeatedly used for more than 6 times, and has a wide application prospect. And the removal efficiency of ethyl carbamate can still reach 88% or above.

Application Domain

Component separationOther chemical processes +2

Technology Topic

BenzeneCovalent organic framework +15

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Examples

Experimental program(8)

Example Embodiment

[0036] A method for preparing a magnetic covalent organic framework nanomaterial disclosed in the present invention comprises the following steps:

[0037] Step 1, Preparation of Magnetic Fe 3 O 4 Nanoparticles;

[0038] The specific preparation method of the present invention is preferably as follows: FeCl 3 , 6H 2 O, Na 3 Cit, 2H 2 O and NaAc were dissolved in ethylene glycol, and stirred for 20 to 50 min. Among them, FeCl 3 , 6H 2 O, Na 3 Cit, 2H 2 The mass ratio of O and NaAc is 2~6:0.5~2:3~7; the obtained mixed solution is placed in an autoclave, reacted at 150℃~200℃ for 8~12h, the obtained product is washed and dried to obtain magnetic Fe 3 O 4 nanoparticles.

[0039] Step 2, the magnetic Fe 3 O 4 Nanoparticles are dispersed in ethanol to give Fe 3 O 4 Dispersion, preferably, magnetic Fe 3 O 4 The mass ratio of the nanoparticles to the volume of absolute ethanol is 0.1-1 g: 5-50 mL; 2,5-dihydroxyterephthalaldehyde is dissolved in ethanol, preferably, the mass of 2,5-dihydroxyterephthalaldehyde The volume ratio to absolute ethanol is 0.01~0.1g:10~30mL; then Fe 3 O 4 The dispersion is mixed with ethanol solution of 2,5-dihydroxyterephthalaldehyde, magnetic Fe 3 O 4 The mass ratio of nanoparticles to 2,5-dihydroxyterephthalaldehyde is 0.1~1:0.03~0.12, preferably 0.5:0.07; the obtained mixed solution is stirred at a temperature of 30~65° C. for 1~3h, and after the reaction solution is cooled Magnetic separation was carried out to obtain Fe after the first modification 3 O 4 Nanoparticles;

[0040] Step 3, the Fe after the first modification 3 O 4 Nanoparticles, 1,3,5-tris(4-aminophenyl)benzene and 2,5-dihydroxyterephthalaldehyde were dispersed in ethanol respectively. Among them, Fe after the first modification 3 O 4 The mass ratio of 1,3,5-tris(4-aminophenyl)benzene and 2,5-dihydroxyterephthalaldehyde is 0.05-0.4:0.01-0.2:0.01-0.1, preferably 0.15:0.07:0.05.

[0041] Fe after first modification 3 O 4 , 1,3,5-tris(4-aminophenyl)benzene, 2,5-dihydroxyterephthalaldehyde and the volume ratio of absolute ethanol are 0.05~0.4g:0.01~0.2g:0.01~0.1g : 30~120m.

[0042] Then, the three solutions are mixed, and then acetic acid solution is added, and the reaction is stirred at room temperature, and the stirring time is preferably 48 to 96 h; after the reaction is completed, magnetic separation is performed, washed and dried to obtain magnetic covalent organic framework nanomaterial Fe. 3 O 4 @COFs. Preferably, the drying temperature is 50-80° C., and the drying time is 15-30 h.

[0043] In the present invention, it is found through experiments that when hydrochloric acid and citric acid are used as catalysts, the final spherical product cannot be obtained, so acetic acid is finally selected as the catalyst. The concentration of the acetic acid solution is preferably 3 to 8 mol/L.

[0044] figure 1 Shown is the synthesis route of the present invention and the reaction mechanism diagram of COFs.

[0045] The magnetic covalent organic framework nanomaterial prepared by the method of the present invention has a spherical particle structure, wherein the spherical particles are composed of magnetic Fe 3 O 4 Nanoparticles and attachment to magnetic Fe 3 O 4 Composition of covalent organic frameworks (COFs) with mesoporous structures on the surface of nanoparticles. Preferably, magnetic Fe 3 O 4 The particle size of the nanoparticles ranges from 10 to 240 nm, and the pore size of the covalent organic framework COFs of the mesoporous structure is 2 to 10 nm; the chemical structural formula of the covalent organic framework of the mesoporous structure is shown in formula (1):

[0046]

[0047] It has been found through experiments that the magnetic covalent organic framework nanomaterials of the present invention can effectively remove urethane in wine. During specific extraction and separation, the present invention adopts magnetic solid phase extraction, and the specific method is as follows:

[0048] will Fe 3 O 4 The @COFs adsorbent was mixed with wine samples, where the wine sample volume was related to Fe 3 O 4 The mass ratio of @COFs adsorbent is 1ml:3mg; after the adsorption is allowed to stand for 30min, it is eluted with n-hexane, the eluent is discarded, and then 5% ethyl acetate-diethyl ether solution (meaning ethyl acetate is the solute diethyl ether is Solvent to prepare 5% solution) eluting, collect the eluate and blow it to near dryness with nitrogen; then check with gas chromatography or liquid chromatography.

[0049] The extraction process of the invention does not need to use a large amount of organic solvents, and the operation is simple and convenient; the problems of using a large amount of organic solvents and time-consuming in the traditional extraction and separation method are solved.

[0050] The present invention is not limited to white wine, and is also applicable to fermented foods such as rice wine, wine, soy sauce, yogurt and the like.

Example Embodiment

[0052] Example 1

[0053] This embodiment discloses the preparation of a magnetic covalent organic framework nanomaterial, specifically:

[0054] Step 1, Magnetic Fe 3 O 4 Preparation of nanoparticles:

[0055] The raw materials are ferric chloride hexahydrate (FeCl 3 , 6H 2 O) 3.4g, dehydrated sodium citrate (Na 3 Cit, 2H 2 O) 1.0 g and sodium acetate (NaAc) 6.0 g. The organic solvent used was 100 mL of ethylene glycol. FeCl 3 , 6H 2 O, Na 3 Cit, 2H 2 O and NaAc were dissolved in ethylene glycol, ultrasonically stirred to form a homogeneous yellow solution, and then transferred to a stainless steel autoclave lined with polytetrafluoroethylene, and reacted at 200° C. for 12 hours. The material was taken out, washed repeatedly with ethanol and water, and dried at 25°C for use.

[0056] Step 2, functionalization of COFs material: take 0.5 g of magnetic Fe prepared in step 1 3 O 4 The particles were ultrasonically dispersed in 25 mL of ethanol, 0.07 g of 2,5-dihydroxyterephthalaldehyde was ultrasonically dissolved in 20 mL of ethanol, and then the two solutions were mixed together in a 250 mL three-necked round-bottomed flask at a temperature of 55 °C. under, stirring for 2.5h. After the solution was cooled, magnetic separation was performed to obtain the first modified Fe 3 O 4 particles, the Fe after the first modification 3 O 4 Wash with ethanol until the wash is clear.

[0057] figure 2 Shown is Fe after first modification 3 O 4 transmission electron microscope image.

[0058] Step 3, the first modified 0.15g Fe 3 O 4 , 70mg 1,3,5-tris(4-aminophenyl)benzene and 50mg 2,5-dihydroxyterephthalaldehyde were respectively dissolved in 5mL, 15mL, 10mL ethanol by ultrasonic wave, then the above homogeneous solution was transferred to stirring In the reactor, 6 mol/L acetic acid solution was added dropwise. The stirring reaction was carried out at room temperature. After the reaction for 72 hours, the magnetic nanocomposite Fe was obtained by collecting the magnet, washing with ethanol for 4 times, and drying at 60°C for 24 hours. 3 O 4 @COFs.

[0059] image 3 The Fe prepared in this example is shown in B and D 3 O 4 TEM image of @COFs; Figure 4 for Fe 3 O 4 FT-IR plots of @COFs, image 3 From top to bottom are COFs, Fe 3 O 4 , Fe 3 O 4 @COFs material; Figure 5 Fe magnetic nanocomposite 3 O 4 Chemical compositions and chemical valence states of elements in @COFs. Comprehensively, it can be concluded that the Fe of this embodiment 3 O 4 @COFs are spherical particle structures, in which the spherical particles are composed of magnetic Fe 3 O 4 Nanoparticles and attachment to magnetic Fe 3 O 4 Composition of COFs on the surface of nanoparticles.

[0060] Image 6 Fe magnetic nanocomposite 3 O 4 BET images of @COFs, indicating that the pore size distribution of COFs in the magnetic nanocomposite is 3.41 nm.

Example Embodiment

[0061] Example 2

[0062] The difference between this embodiment and Embodiment 1 is that in step 2, Fe 3 O 4 It is 0.15g, and 2,5-dihydroxyterephthalaldehyde is 0.03g.

[0063]The magnetic nanocomposite Fe prepared in this example 3 O 4 The topography of @COFs is similar to that in Example 1 and is not presented separately here.

PUM

Property	Measurement	Unit
Concentration	3.0 ~ 8.0	mol/l
Particle size range	10.0 ~ 240.0	nm
Aperture	2.0 ~ 10.0	nm

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Classification and recommendation of technical efficacy words

Many adsorption sites
Large specific surface area

Ferromagnetic biochar spheres for purifying water bodies and preparation method and application thereof

PendingCN109277083AMany adsorption sitesWide variety of sources

Owner:OCEAN UNIV OF CHINA

Synergistic illumination and fermentation efficient panus giganteus culture medium and preparation method thereof

InactiveCN108623368AMany adsorption sitesLarge specific surface area

Owner:德阳市明润农业开发有限公司

Magnetic covalent organic framework nano material, preparation method and application

AI-Extracted Technical Summary

Problems solved by technology

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Abstract

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Example Embodiment

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Description & Claims & Application Information

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