CN116099508A - Rapid preparation method and application of supermolecule cyclodextrin metal organic framework and graphene composite material - Google Patents

Abstract

The invention provides a rapid preparation method and application of a supermolecule cyclodextrin metal organic framework and graphene composite material. The synergistic effect of the supermolecule cyclodextrin and the graphene is realized, and the supermolecule cyclodextrin can be widely applied. According to the invention, cyclodextrin, potassium hydroxide and nucleating agent graphene are dissolved in distilled water according to a certain proportion, and are rapidly stirred, and methanol is added as a reaction solvent in the stirring process. And (3) realizing the rapid crystallization of the cyclodextrin metal organic framework by utilizing a microwave method, and completing the compounding on the surface of the graphene. The method fully utilizes the characteristics of rapid synthesis of crystals by microwaves and providing nucleation sites for graphene, and the reaction is completed within a few minutes, so that the problem of long time for preparing the cyclodextrin metal-organic frame in the past is fully solved. Has very wide application prospect in the aspect of adsorbing and treating organic dye.

Description

A rapid preparation method and application of supramolecular cyclodextrin metal-organic framework and graphene composites

technical field

The invention relates to polymer composite materials, in particular to the adsorption application of polymer cyclodextrin metal organic frameworks to organic dyes.

Background technique

Cyclodextrins are mainly divided into three types: α, β, and γ-cyclodextrins. γ-cyclodextrin, as a C ₈ -symmetric cyclic oligosaccharide, is composed of eight asymmetric α-1,4-linked D-glucopyranoside residues, and has a multipurpose nano-hydrophobic cavity. The barrel-shaped hydrophobic cavity can serve as a molecular host unit, which can connect various organic/biological matrices. This structural feature greatly facilitates the synergy of host-guest molecular functions and interactions with active sites. Cyclodextrin metal-organic frameworks are derived from γ-cyclodextrin and K ⁺ , and have a series of advantages such as porous, renewable, edible, and large-scale production. This kind of MOFs derived from natural carbohydrates was discovered in 2010 (Angew.Chem.Int.Ed.Engl.2010, 49, 8630-8634), and it is the first cyclodextrin-based metal-organic framework with high crystallinity.

Graphene oxide is a new type of two-dimensional sheet, which has been widely studied because of its excellent electrical and thermal conductivity, strong mechanical strength, and good stability. The invention uses graphene oxide as a high-quality nucleation solvent to provide a large number of nucleation sites, which is conducive to the attachment and growth of the cyclodextrin metal organic framework on its surface. Meanwhile, the hydrophobic cavity of γ-cyclodextrin and the negatively charged surface of graphene oxide have a special synergistic effect, which is also very promising for the adsorption of organic dyes.

The traditional synthesis method mainly has the problems of long synthesis time and high energy consumption. For example, the publication number CN114702687A discloses a preparation method and application of cyclodextrin MOF particle antibiotic substitute. Dozens of hours or even two weeks. The microwave preparation method adopted in the invention greatly improves the preparation efficiency, shortens the production time and saves energy consumption. The prepared composite material not only combines the special structure of cyclodextrin, but also retains the flexible characteristics of metal-organic framework materials in synthesis and design. Moreover, it has high-efficiency selective adsorption to the dye solution, and has wide application prospects.

Contents of the invention

Aiming at the deficiencies of the prior art, the technical problems to be solved by the present invention are: long preparation time of the cyclodextrin metal organic framework, determination of the dye type for selective adsorption, and inability to fully utilize supramolecular interactions to achieve efficient adsorption of organic dyes.

In order to realize the purpose of the present invention, the technical scheme adopted in the present invention is: the microwave method is preferably used as the nucleation method of the cyclodextrin metal-organic framework, and graphene oxide is used as a nucleating agent to rapidly nucleate and grow the cyclodextrin metal-organic framework crystal to obtain Cyclodextrin metal-organic framework and graphene composites.

The invention also discloses a rapid preparation method of supramolecular cyclodextrin metal organic framework and graphene composite material, which is synthesized according to the following steps:

Weigh a certain mass ratio of cyclodextrin and potassium hydroxide, dissolve them in ionized water, control the uniformity of compounding by changing the content of graphene oxide, stir well and mix evenly, add methanol solution during the stirring process, and put the mixed solution into the microwave In , the reaction was continued to obtain cyclodextrin metal-organic framework and graphene composites, which were left to stand, washed with methanol and dried.

Preferably, the mass ratio of cyclodextrin to potassium hydroxide is 1:8.

Preferably, the volume of the deionized water is 12ml.

Preferably, the concentration of the graphene oxide is 3g/L.

Preferably, the stirring rate is 700ppm.

Preferably, the stirring time is 1 h.

Preferably, the volume of the added methanol is 12ml.

Preferably, the power of the microwave is 100W.

Preferably, the microwave reaction time is 270s.

The present invention also discloses that cyclodextrin metal organic framework and graphene composite material can be used for the application of efficient and selective adsorption of dyes, which is completed according to the following steps:

The obtained cyclodextrin metal-organic framework and graphene composite were respectively placed in methanol solutions of methyl orange, methylene blue and methylene green molecules, and the adsorption effect was determined by color observation and ultraviolet test.

Preferably, the solution concentrations of the methyl orange, methylene blue and methylene green are 10 mg/L.

Preferably, the adsorption time is 72h.

Compared with the prior art, the present invention has the following beneficial effects:

1. Achieved rapid preparation, green and low energy consumption, and obtained cyclodextrin metal organic framework and graphene composite materials. Traditional preparation methods used in the past, such as: steam diffusion method, hydrothermal method, ultrasonic synthesis method, etc. (Appl Surf Sci, 500, 2020. Food Chem, 338, 127839, 2021.). The synthesis cycle is too long, ranging from several weeks to tens of minutes. The microwave-assisted synthesis of the present invention greatly reduces the synthesis time, and the preparation can be completed within a few minutes.

2. Utilize the hydrophobic cavity of γ-cyclodextrin for efficient and selective adsorption. There are many ways to treat dye wastewater. The adsorption method is considered to be the most effective and rapid method for treating dye wastewater, and it uses van der Waals force, electrostatic interaction, π-π and other intermolecular interactions between the adsorbate and the adsorbent to selectively adsorb dyes. Due to the excellent surface structure, large specific surface area, and rich pore size distribution of the prepared cyclodextrin metal organic framework and graphene composite, combined with the cavity structure of γ-cyclodextrin, the adsorption effect is obvious. Moreover, the surface of the composite material has more oxygen-containing functional groups, and the adsorption effect on cationic dyes is more prominent. When dealing with the mixed solution of methyl orange, methylene blue and methylene green, the cyclodextrin metal-organic framework and graphene composite can achieve highly selective adsorption of MG in such a complex environment, and the adsorption effect is obvious , good adsorption capacity.

Description of drawings

Figure 1 is a scanning electron microscope image of cyclodextrin metal organic framework and graphene composite material. The concentration of graphene oxide is (a) 0g/L; (b) 0.1g/L; (c) 3g/L; (d) 4g /L

Figure 2 is the Fourier transform infrared spectrum of cyclodextrin metal organic framework and graphene composite

Figure 3 is the adsorption UV-visible spectrum within 72h, (a) methyl orange, (b) methylene blue, (c) methylene green

Figure 4 is the ultraviolet-visible spectrum diagram of the three kinds of dye mixed solution adsorption within 72h

Figure 5 is a graph showing the relationship between the solution concentration of different dyes and the intensity of the UV-Vis spectrum, (a) methyl orange, (b) methylene blue, (c) methylene green

Figure 6 is a graph showing the relationship between the amount of adsorption of methylene green and time

Fig. 7 is the relationship diagram of the solution concentration and time of methylene green

Detailed ways

In order to make the above objects, features and advantages of the present invention more obvious and comprehensible, specific implementations of the present invention will be described in detail below in conjunction with the accompanying drawings. In the following description, a lot of specific details are set forth in order to fully understand the present invention. Those skilled in the art can make similar extensions without violating the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

The experimental methods in the following examples are conventional methods unless otherwise specified. Unless otherwise specified, the test materials used in the following examples were purchased from commercial sources.

1. Preparation of cyclodextrin metal-organic framework and graphene composites.

Example 1

This example provides a rapid preparation method and application of a supramolecular cyclodextrin metal organic framework and graphene composite material

Weigh 778mg of γ-cyclodextrin, 269mg of potassium hydroxide, dissolve in 12ml of deionized water, add 1.2mg of graphene oxide to make its concentration 0.1g/L, stir rapidly for 30min, and add 12ml of methanol solution during stirring. The mixed solution was microwave crystallized under 100W power, and the reaction time was 270s. After the reaction was completed, the reaction solution was taken out and left to stand for 30 min, then washed repeatedly with 25 ml of methanol and dried.

Example 2

This example provides a rapid preparation method and application of a supramolecular cyclodextrin metal organic framework and graphene composite material

Weigh 778mg of γ-cyclodextrin, 269mg of potassium hydroxide, dissolve in 12ml of deionized water, add 36mg of graphene oxide to make its concentration 3g/L, stir rapidly for 30min, and add 12ml of methanol solution during stirring. The mixed solution was microwave crystallized under 100W power, and the reaction time was 270s. After the reaction was completed, the reaction solution was taken out and left to stand for 30 min, then washed repeatedly with 25 ml of methanol and dried.

Example 3

This example provides a rapid preparation method and application of a supramolecular cyclodextrin metal organic framework and graphene composite material

Weigh 778mg of γ-cyclodextrin, 269mg of potassium hydroxide, dissolve in 12ml of deionized water, add 48mg of graphene oxide to make its concentration 4g/L, stir rapidly for 30min, and add 12ml of methanol solution during stirring. The mixed solution was microwave crystallized under 100W power, and the reaction time was 270s. After the reaction was completed, the reaction solution was taken out and left to stand for 30 min, then washed repeatedly with 25 ml of methanol and dried.

Example 4

This example provides a rapid preparation method and application of a supramolecular cyclodextrin metal organic framework and graphene composite material

Weigh 778mg of γ-cyclodextrin and 269mg of potassium hydroxide, dissolve in 12ml of deionized water, stir rapidly for 30min, and add 12ml of methanol solution during stirring. The mixed solution was microwave crystallized under 100W power, and the reaction time was 270s. After the reaction was completed, the reaction solution was taken out and left to stand for 30 min, then washed repeatedly with 25 ml of methanol and dried.

Adsorption experiment, cyclodextrin metal organic framework and graphene composite material adsorption organic dye steps are as follows:

The experimental products cyclodextrin metal organic framework and graphene composite material in Example 3 were used for adsorption experiments, and 10 mg/L solutions of methyl orange, methylene blue and methylene green were prepared respectively. Add cyclodextrin MOF and graphene composite to the dye solution and let stand for 72h. The color of the solution became lighter and the adsorption effect was obvious. The saturated adsorption amounts of methyl orange, methylene blue and methylene green at 25°C were 4.40mg/g, 3.53mg/g and 25.28mg/g respectively. Then prepare a mixed solution of 10 mg/L of the three dyes, add cyclodextrin metal organic framework and graphene composite, and let it stand for 72 hours. The adsorption effect on methylene green is the best, and it has high selectivity.

Characterization of Cyclodextrin Metal Organic Framework Graphene Composite

1. Scanning electron microscope

Taking Examples 1-4 as an example, scan images of cyclodextrin metal-organic frameworks and graphene composites prepared with different concentrations of graphene oxide were obtained. As shown in Figure 1, the cubic crystals of non-oxide graphene are obviously larger in size, reaching 5-10 μm, and the sizes are different. Cyclodextrin metal-organic frameworks and graphene composites prepared with 0.1g/L graphene oxide can see a small amount of wrinkled graphene oxide with a slightly reduced size reaching 3-8 μm. When the graphene oxide concentration reaches 3g/L, it is obvious that the size of the cubic crystals is more uniform, reaching 0.5-1 μm, and the wrinkled graphene oxide is evenly distributed in the middle of the cubic crystals. When the concentration of graphene oxide is too high, reaching 4g/L, it can be seen that graphene has wrapped the cyclodextrin metal-organic framework, and the cubic structure cannot be displayed.

2. Fourier transform infrared spectroscopy test

Taking Example 4 as an example, the prepared γ-cyclodextrin metal organic framework was subjected to infrared testing, and the test results are shown in Figure 2. It can be seen that the diffraction peaks at 3423, 1155, and 1029 cm ^-1 are wide and long, It shows that the -OH and -COOH stretching vibrations represented by the diffraction peaks are more obvious. γ-cyclodextrin retains a large number of oxygen-containing groups during the crystallization process.

3. Determination of adsorption capacity by ultraviolet-visible spectroscopy

Taking the adsorption experiment as an example, the ultraviolet absorption spectra of different dyes before and after adsorption were tested. The test results are shown in Figure 3. As time goes by, the intensity of the characteristic peak of methylene green decreases significantly, indicating that the adsorption effect on methylene green is good. . Then observe the ultraviolet test results before and after the adsorption of the mixed solution of the three dyes of methyl orange, methylene blue, and methylene green in Figure 4. It is obvious that the characteristic peak of methylene green decreases, indicating that cyclodextrin metal organic framework and graphene The composite material has efficient and selective adsorption on methylene green. Combined with Lambert-Beer's law A=ε·c·d, the relationship between the concentration and adsorption amount of different dyes in Figure 5 is obtained. Reuse adsorption capacity calculation formula The adsorption capacities of methyl orange, methylene blue and methylene green at 25°C were 4.40mg/g, 3.53mg/g and 25.28mg/g respectively. Figure 6 is the relationship between the amount of methylene green adsorption and time, and Figure 7 is the relationship between the concentration and time in the methylene green solution, it can be concluded that cyclodextrin metal organic frameworks and graphene composites are effective for methylene green Efficient selective adsorption, and good adsorption capacity, can be applied in dye wastewater treatment.

It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention without limitation, although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be carried out Modifications or equivalent replacements without departing from the spirit and scope of the technical solution of the present invention shall be covered by the claims of the present invention.

Claims (10)

1. a kind of fast preparation method of supramolecular cyclodextrin metal organic framework and graphene composite material, it is characterized in that, synthesize according to the following steps: Weigh a certain mass ratio of cyclodextrin, potassium hydroxide and nucleating agent graphene, dissolve in deionized water, and stir rapidly with a mixer to make it fully mixed; during the stirring process, add methanol as a reaction solvent; mix the mixture Put it into a microwave reactor, take it out after microwave reaction, pour it into methanol solution to induce the growth of gray crystal cyclodextrin metal organic framework, let it stand, and then wash it with methanol; fully dry to obtain the final product supramolecular cyclodextrin metal organic framework and Graphene composites. 2. the rapid preparation method of a kind of supramolecular cyclodextrin metal organic framework and graphene composite material according to claim 1, is characterized in that, the kind of described cyclodextrin is respectively α, β, γ-cyclodextrin One or a mixture of the three; the graphene is graphene oxide, and the control range of oxygen content is 20%-40%. 3. the rapid preparation method of a kind of supramolecular cyclodextrin metal organic framework and graphene composite material according to claim 1, is characterized in that, the mass ratio of described cyclodextrin and potassium hydroxide is 1: 1- 1:5, the mass of the cyclodextrin is 500-1000 mg, and the mass of the potassium hydroxide is 100-400 mg. 4. the rapid preparation method of a kind of supramolecular cyclodextrin metal organic framework and graphene composite material according to claim 2, is characterized in that, described graphene oxide concentration is 0.1-4g/L. 5. the rapid preparation method of a kind of supramolecular cyclodextrin metal organic framework and graphene composite material according to claim 1, is characterized in that, the stirrer rotating speed that described stirring process uses is 600-900ppm, and described stirring The time is controlled at 10-90min. 6. The rapid preparation method of a supramolecular cyclodextrin metal organic framework and graphene composite material according to claim 1, characterized in that, the volume of the methanol solution added during the stirring process is 10-40ml. 7. the rapid preparation method of a kind of supramolecular cyclodextrin metal organic framework and graphene composite material according to claim 1, it is characterized in that, the power used in the microwave process is 50-300W, and the microwave The reaction time is 150-360s. 8. the rapid preparation method of a kind of supramolecular cyclodextrin metal organic framework and graphene composite material according to claim 1, it is characterized in that, after described microwave finishes, microwave product needs to be added the methyl alcohol of 40-100ml Solution, carry out induced growth to obtain small particle size cubic crystal cyclodextrin metal organic framework and graphene composite material, the standing time is 10-30min, the methanol solution volume of the washed crystal is 20-80ml, the cyclodextrin The fine metal organic framework size is 0.2-5μm. 9. An application of a supramolecular cyclodextrin metal-organic framework and a graphene composite material, characterized in that, the adsorption application is carried out according to the following steps: Weigh the supramolecular cyclodextrin metal-organic framework and graphene composite material prepared as claimed in claim 1, add it to the methanol solution of organic dye at room temperature, and let it stand for adsorption for a certain period of time. 10. the application of a kind of supramolecular cyclodextrin metal organic framework and graphene composite material according to claim 9, is characterized in that, described organic dyestuff is methyl orange, methylene blue, methylene green; Described organic The concentration of the dyes methyl orange, methylene blue and methylene green in the methanol solution is 5-50 mg/L, and the saturated adsorption capacity of the three organic dyes of methyl orange, methylene blue and methylene green at room temperature is 4.40 mg/L respectively. mg/g, 3.53mg/g and 25.28mg/g; the adsorption time of the supramolecular cyclodextrin metal organic framework and the graphene composite material to the dye solution is controlled within 12-90h, and the methyl orange, methylene blue, methylene There is high selectivity to methylene green in the mixed solution of base green three.

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