Preparation method of multi-metal organic framework modified graphene oxide microspheres

Abstract

The application discloses a preparation method of multi-metal organic framework modified graphene oxide microspheres. The prepared microspheres are coated with multiple layers of graphene oxide on the surface of ethyl vinylbenzene / divinylbenzene (EVB / DVB) microspheres, and then the multi-metal organic framework is modified on the surface of the graphene oxide. The application uses graphene oxide as an intermediate to connect the metal organic framework and the polymer, thereby improving the stability of the material. The EVB / DVB microspheres are used as the matrix of the metal organic framework, so that the stability of the metal organic framework can be enhanced, and the metal organic framework is convenient for centrifugal recovery. The composite material can provide coordination, hydrophobic and pi-pi conjugation, thereby improving the affinity of the material to bisphenol substances, and the adsorption of the bisphenol organic substances is obviously improved. The metal organic framework is bonded to the microspheres, so that the specific surface area is increased, the contact area with the bisphenol substances is increased, and the adsorption efficiency is improved.

Description

Technical Field

[0001] This invention belongs to the field of food testing technology, specifically, it relates to a method for preparing graphene oxide microspheres modified with a multi-metal-organic framework. Background Technology

[0002] Bisphenols, as synthetic monomers, are widely used in the manufacture of containers for storing food and beverages, and are among the most produced compounds in the world. Studies have shown that bisphenols on packaging materials can migrate into food and thus enter the human body. Long-term exposure to bisphenol compounds, especially bisphenol A, can cause various endocrine disorders. [1] Therefore, the use of bisphenol A (BPA) is prohibited or limited in many consumer products. In 2018, the European Union issued new regulations stipulating that the migration limit of BPA from packaging to food must not exceed 50 μg / kg. -1 Following the strict regulation of bisphenol A, other bisphenols with similar structures have been developed as alternatives and are widely used in food matrices. Therefore, it is necessary to develop a sensitive, efficient, and rapid method for determining bisphenol compounds in food matrices. [2] Due to the complexity of food matrices and the low concentration of bisphenols, appropriate pretreatment is generally required to eliminate the influence of the matrix and enrich the bisphenols. Developing suitable enrichment materials is the key to achieving effective pretreatment.

[0003] Metal-organic frameworks (MOFs) are porous materials with high surface area, multiple functional sites, and modifiability. These properties make them ideal adsorbents for separating and enriching trace analytes. To further improve their performance, the Yaghi team first proposed multi-metal-organic frameworks with two or more metals / ligands in 2010. [3] The introduction of multiple functional metals or ligands results in a superior porous structure, and the synergistic effect of various functional groups gives it greater potential for adsorption. However, metal-organic frameworks are primarily in powder form due to their inherent properties, which poses significant challenges to material recycling and industrial applications. Therefore, metal-organic frameworks are often combined with polymers to form composite materials for pretreatment. [4] In this context, the dispersibility of metal-organic framework (MOF) particles and their interfacial compatibility with the polymer are two key factors determining the morphology, quality, and practicality of the composite material. The surface of polymer microspheres consists of hydrophobic benzene rings; if MOFs are directly generated in situ on their surface, the composite material exhibits poor stability. Modifying the surface of polymer microspheres with MOFs using appropriate methods to form stable compounds is a hot research topic. [5] .

[0004] To address the aforementioned issues, this study proposes to improve the bisphenol extraction capability of zirconium-based metal-organic frameworks (MOFs) by doping them with 1,3,5-tris(4-carboxyphenyl)benzene during the one-pot preparation of MOFs. Simultaneously, graphene oxide will be introduced onto the microsphere surface to improve the microspheres' hydrophilicity and provide bonding sites, thereby enabling the preparation of stable MOF / polymer composites and expanding the application range of MOFs.

[0005] References

[0006] [1]J.Liu,L.Zhang,G.Lu,R.Jiang,Z.Yan,Y.Li.Occurrence,toxicity andecological risk of Bisphenol A analogues in aquatic environment-Areview.Ecotoxicol Environ Saf 208(2021)111481.

[0007] [2]Y.Ning,Y.Xu,J.Bao,W.Wang,AJWang.beta-cyclodextrin-functionalizedmagnetic graphene oxide for the efficient enrichment of bisphenols in milkand milk packaging.J.Chromatogr.A.1692(2023)463854.

[0008] [3]H.Deng,CJDoonan,H.Furukawa,RBFerreira,J.Towne,CBKnobler,B.Wang,OMYaghi.Multiple functional groups of varying ratios in metal-organic frameworks.Science 327(2010)846-50.

[0009] [4]K.-G.Liu,F.Bigdeli,Z.Sharifzadeh,S.Gholizadeh,A.Morsali.Role of metal-organic framework composites in removal of inorganic toxiccontaminants.J.Clean.Prod.404(2023)136709.

[0010] [5] D. Giliopoulos, A. Zamboulis, D. Giannakoudakis, D. Bikiaris, K. Triantafyllidis. Polymer / Metal Organic Framework (MOF) Nanocomposites for Biomedical Applications. Molecules 25 (2020) Summary of the Invention

[0011] To address the shortcomings of existing technologies, this invention provides a method for preparing multi-component metal-organic framework-modified graphene oxide microspheres through extensive experimental screening. The aim is to achieve the rapid synthesis and application of metal-organic framework-modified graphene oxide microsphere composite materials.

[0012] This invention is achieved through the following technical solution:

[0013] This invention discloses a method for preparing graphene oxide microspheres modified with a multi-element metal-organic framework (MOF). The prepared microspheres are made by coating multiple layers of graphene oxide onto the surface of ethyl vinylbenzene / divinylbenzene (EVB / DVB) microspheres, followed by modification of the graphene oxide surface with a multi-element MOF, specifically a 1,3,5-tris(4-carboxyphenyl)benzene-doped aminated UiO-66 MOF. The use of graphene oxide as an intermediate layer enhances the stability between the MOF and the polymer microspheres.

[0014] As a further improvement, the metal-organic framework of the present invention is formed by reacting 2-aminoterephthalic acid, 1,3,5-tris(4-carboxyphenyl)benzene with zirconium chloride to form a multi-metal-organic framework.

[0015] As a further improvement, the specific preparation steps described in this invention are as follows:

[0016] 1) Add ethyl vinylbenzene / divinylbenzene (EVB / DVB) microspheres to an ethanol solution and sonicate at room temperature to obtain an EVB / DVB microsphere solution;

[0017] 2) Add the graphene oxide solution to the EVB / DVB microsphere solution obtained in step 1), sonicate at room temperature, then centrifuge, wash with ethanol, and dry to obtain graphene oxide microspheres (EVB / DVB@GO).

[0018] 3) Dissolve the graphene oxide microspheres and zirconium chloride obtained in step 2) in N,N-dimethylformamide and sonicate at room temperature to obtain a uniform suspension.

[0019] 4) Add 2-aminoterephthalic acid, 1,3,5-tris(4-carboxyphenyl)benzene and acetic acid catalyst to the homogeneous suspension obtained in step 3), carry out a high-temperature hydrothermal reaction, then centrifuge, wash with methanol, and dry to obtain multi-metal-organic framework modified graphene oxide microspheres (EVB / DVB@GO@UIO-66 / H3BTB3).

[0020] As a further improvement, in step 1) of the present invention, the concentration of EVB / DVB microspheres in ethanol is 3-7 g / L.

[0021] As a further improvement, in step 2) of the present invention, the volume ratio of graphene oxide solution to solution is 1:50-1:100.

[0022] As a further improvement, in step 3) of the present invention, the concentration of zirconium chloride is 1.1-2.3 g / L and the concentration of EVB / DVB@GO is 0.5-1.0 g / L.

[0023] As a further improvement, in step 4) of the present invention, the mass ratio of 2-aminoterephthalic acid to 1,3,5-tris(4-carboxyphenyl)benzene is 100:1-100:5.

[0024] The present invention has the following advantages and effects:

[0025] 1. This invention uses graphene oxide as an intermediate to connect metal-organic frameworks and polymers, thereby improving material stability;

[0026] 2. This invention uses EVB / DVB microspheres as the matrix of the metal-organic framework, which can enhance its stability and facilitate centrifugal recovery;

[0027] 3. The composite material proposed in this invention can provide coordination, hydrophobic and π-π conjugation, which improves the material’s affinity for bisphenols and significantly enhances the adsorption of bisphenol organic compounds.

[0028] 4. This invention bonds metal-organic frameworks to microspheres, increasing the specific surface area and the contact area with bisphenol substances, thereby improving adsorption efficiency. Attached Figure Description

[0029] Figure 1 A schematic diagram illustrating the preparation of self-made multi-metal-organic framework modified graphene oxide microspheres;

[0030] Figure 2 A schematic diagram of the extraction and separation process of bisphenol compounds in milk samples by multi-metal-organic framework modified graphene oxide microspheres. Detailed Implementation

[0031] This invention discloses a method for preparing multi-metal-organic framework modified graphene oxide microspheres. A graphene solution is added distributively to a white solution containing EVB / DVB microspheres to generate brown microspheres (EVB / DVB@GO) with graphene oxide adsorbed on their surface. Then, high concentrations of the reactive monomers zirconium chloride, 2-aminoterephthalic acid, 1,3,5-tris(4-carboxyphenyl)benzene, and the catalyst acetic acid are added. The mixture is transferred to a reaction vessel and subjected to a hydrothermal reaction at high temperature to obtain multi-metal-organic framework modified graphene oxide microspheres. The specific preparation steps are as follows:

[0032] 1) Add EVB / DVB microspheres to an ethanol solution and sonicate at room temperature. The concentration of EVB / DVB microspheres in ethanol is 5 g / L and the sonication time is 30 minutes.

[0033] 2) Add the graphene oxide solution to the EVB / DVB microsphere solution obtained in step 1), sonicate at room temperature, the volume ratio of graphene oxide solution to solution is 1:100, the reaction time is 10 minutes, centrifuge, wash three times with ethanol, and dry to obtain brown graphene oxide microspheres (EVB / DVB@GO).

[0034] 3) Dissolve the graphene oxide microspheres and zirconium chloride obtained in step 2) in N,N-dimethylformamide, with a zirconium chloride concentration of 2.3 g / L and an EVB / DVB@GO concentration of 1.0 g / L. Sonicate at room temperature to obtain a uniform suspension.

[0035] 4) Add 2-aminoterephthalic acid, 1,3,5-tris(4-carboxyphenyl)benzene, and acetic acid catalyst to the suspension obtained in step 3), and perform a high-temperature hydrothermal reaction. The concentration of 2-aminoterephthalic acid in N,N-dimethylformamide is 1.8 g / L, the concentration of 1,3,5-tris(4-carboxyphenyl)benzene in N,N-dimethylformamide is 0.054 g / L, and the concentration of acetic acid catalyst in N,N-dimethylformamide is 0.2 g / L. The reaction time is 24 hours, the reaction temperature is 180℃, centrifuge, wash with methanol, and dry to obtain multi-metal-organic framework modified graphene oxide microspheres (EVB / DVB@GO@UIO-66 / H3BTB3). The washing is performed 3 times, and the centrifuge speed is 5000 rpm.

[0036] The technical solution of the present invention will be further described below with reference to the accompanying drawings:

[0037] This invention prepares a novel extraction material by using a multi-metal-organic framework modified graphene oxide microsphere. This material is obtained through an in-situ reaction method and selectively enriches bisphenolic substances in milk using simple solid-phase extraction, exhibiting high enrichment efficiency. The microspheres are then injected into high-performance liquid chromatography (HPLC) for separation and analysis using a UV detector.

[0038] Figure 1 This diagram illustrates the preparation of self-made multi-metal-organic framework modified graphene oxide microspheres. The specific preparation process is as follows:

[0039] Microspheres (EVB / DVB, 1 g) were added to 200 mL of ethanol and uniformly dispersed by sonication for 30 minutes. 2 mL of graphene oxide solution was added to the dispersed microsphere solution and sonicated for 10 minutes to ensure sufficient graphene adsorption on the microsphere surface. After treatment, the microspheres were washed three times with ethanol, centrifuged, and dried. 50 mg of graphene-modified microspheres were added to 50 mL of N,N-dimethylformamide, followed by 115 mg of zirconium chloride and sonicated for 20 minutes. Then, 90 mg of 2-aminoterephthalic acid, 2.7 mg of 1,3,5-tris(4-carboxyphenyl)benzene, and 10 mg of acetic acid catalyst were added. 50 mL of the solution was transferred to a 100 mL reactor and reacted at 180 °C for 24 h. The deposits at the bottom of the reactor were washed three times with methanol. Finally, the obtained multi-metal-organic framework-modified graphene oxide microspheres were dried in a 60 °C oven and stored.

[0040] Figure 2 This is a schematic diagram illustrating the extraction and separation process of bisphenol compounds from milk samples using graphene oxide microspheres modified with a multi-metal-organic framework. The process of extracting bisphenol compounds from milk samples using graphene oxide microspheres modified with a multi-metal-organic framework is as follows:

[0041] Step 1, Sample preparation: Mix 50 mL of milk sample with 3.3 mL of 20% acetic acid solution and 46.7 mL of ultrapure water, shake well, and store in a 4°C refrigerator for 15 minutes. Then centrifuge the sample at 3000 rpm for 5 minutes and pass it through a 0.45 μM hydrophilic filter membrane.

[0042] The second step, enrichment: 30 mg of graphene oxide microspheres modified with a multi-metal-organic framework and 30 mL of sample solution were added to a centrifuge tube, and then sonicated in a water bath for 10 min to ensure sufficient adsorption. After centrifugation, the supernatant was discarded, and the sample was sonicated with 1 mL of acetonitrile for 10 min to elute bisphenol compounds from the adsorbent. After elution, the sample was centrifuged again, and the desorption solvent was transferred to another centrifuge tube. The desorption solvent was completely evaporated with nitrogen at 60 °C, and the extract was diluted to 100.0 μL with acetonitrile. Finally, 25 μL of the resulting solution was injected into an HPLC-UV system.

[0043] The second step, analysis: Analysis of bisphenol compounds was performed on an Ultimate 3000 HPLC system. The analytes were separated using a self-made C18 column (250 mm × 4.6 mm, ID 5.0 ​​μm) at 35 °C. A mobile phase consisting of acetonitrile (A) and water (B) was introduced at a flow rate of 1.0 mL / min. -1Pumping was performed. The gradient program was selected as follows: 0 min, 50% A; 0–4 min, 50–70% B; 4–8 min, 70%–50% A; 8–12 min, 50% A. Chromatographic data of the analytes were collected at 229 nm.

[0044] Finally, it should be noted that the above examples are merely specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments, and many variations are possible. All variations that can be directly derived or conceived by those skilled in the art from the disclosure of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A method for preparing multi-metal-organic framework modified graphene oxide microspheres, characterized in that, The microspheres prepared were made by coating the surface of ethyl vinylbenzene / divinylbenzene EVB / DVB microspheres with multiple layers of graphene oxide, and then modifying the surface of the graphene oxide with a multi-element metal-organic framework, namely 1,3,5-tris(4-carboxyphenyl)benzene-doped aminated UiO-66 metal-organic framework.

2. The method for preparing multi-metal-organic framework modified graphene oxide microspheres according to claim 1, characterized in that, The metal-organic framework is formed by reacting 2-aminoterephthalic acid, 1,3,5-tris(4-carboxyphenyl)benzene with zirconium chloride to form a multi-metal-organic framework.

3. The method for preparing multi-metal-organic framework modified graphene oxide microspheres according to claim 1 or 2, characterized in that, The specific preparation steps are as follows: 1) Add ethyl vinylbenzene / divinylbenzene EVB / DVB microspheres to an ethanol solution and sonicate at room temperature to obtain an EVB / DVB microsphere solution; 2) Add the graphene oxide solution to the EVB / DVB microsphere solution obtained in step 1), sonicate at room temperature, then centrifuge, wash with ethanol, and dry to obtain graphene oxide microspheres, denoted as EVB / DVB@GO. 3) Dissolve the graphene oxide microspheres and zirconium chloride obtained in step 2) in N,N-dimethylformamide and sonicate at room temperature to obtain a uniform suspension. 4) Add 2-aminoterephthalic acid, 1,3,5-tris(4-carboxyphenyl)benzene and acetic acid catalyst to the homogeneous suspension obtained in step 3), carry out a high-temperature hydrothermal reaction, then centrifuge, wash with methanol, and dry to obtain multi-metal-organic framework modified graphene oxide microspheres, denoted as EVB / DVB@GO@UIO-66 / H3BTB3.

4. The method for preparing multi-metal-organic framework modified graphene oxide microspheres according to claim 3, characterized in that, In step 1), the concentration of EVB / DVB microspheres in ethanol is 3-7 g / L.

5. The method for preparing multi-metal-organic framework modified graphene oxide microspheres according to claim 4, characterized in that, In step 2), the volume ratio of the graphene oxide solution to the EVB / DVB microsphere solution is 1:50-1:

100.

6. The method for preparing multi-metal-organic framework modified graphene oxide microspheres according to claim 4 or 5, characterized in that, In step 3), the concentration of zirconium chloride is 1.1-2.3 g / L, and the concentration of graphene oxide microspheres EVB / DVB@GO is 0.5-1.0 g / L.

7. The method for preparing multi-metal-organic framework modified graphene oxide microspheres according to claim 6, characterized in that, In step 4), the mass ratio of 2-aminoterephthalic acid to 1,3,5-tris(4-carboxyphenyl)benzene is 100:1-100:5.

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