Iron-doped ZIF-67 derived magnetic Fe-Co-C composite material, and preparation method and application thereof

Abstract

This invention discloses an iron-doped ZIF-67-derived magnetic Fe-Co-C composite material, its preparation method, and its application in the field of material synthesis. The preparation method includes the following steps: (1) dissolving chitosan, ZIF-67, and ferric chloride in a 2% acetic acid solution, stirring, centrifuging, washing with ethanol, and drying overnight in an oven to obtain sample A; (2) carbonizing sample A in a tube furnace filled with nitrogen to obtain sample B; (3) further carbonizing sample B in a muffle furnace to obtain the iron-doped ZIF-67-derived magnetic Fe-Co-C composite material. The iron-doped ZIF-67-derived magnetic Fe-Co-C composite material prepared by this invention has good adsorption capacity for dyes such as Congo red and has good magnetic properties. With the help of an external magnetic field, it effectively enhances the material's ability to separate from the environmental medium, solves the technical problem of difficult material recycling, facilitates recycling, and reduces usage costs.

Description

Technical Field

[0001] This invention relates to the field of materials synthesis, and in particular to an iron-doped ZIF-67-derived magnetic Fe-Co-C composite material, its preparation method, and its application. Background Technology

[0002] With the rapid development of technology, environmental pollution problems are becoming increasingly serious. Dye pollution, as one type, has gained significant attention. The continuous accumulation of dyes in the atmosphere, water bodies, and soil can have severe impacts on the environment and human health. Currently, many methods have been applied to dye treatment, such as adsorption, photocatalysis, and electrocatalysis. Adsorption is favored due to its simplicity and low cost. The adsorption material affects the adsorption effect; commonly used adsorption materials include activated carbon, biochar, and metal-organic frameworks.

[0003] Metal-organic frameworks, or MOFs for short, are porous metallic materials composed of metal coordination centers and organic ligands. They possess characteristics such as high specific surface area, fixed porosity, low crystal density, and diverse topological structures. MOF-derived materials, carbonized using specific methods, have been shown in numerous studies to retain their original porous structure and exhibit enhanced adsorption properties.

[0004] Chinese patent CN115430403A discloses a MOF-type hydroxylated UiO-66 organic dye adsorbent, its preparation method, and its application. This method uses zirconium as the metal source and 2,5-dihydroxyterephthalic acid as the organic ligand to synthesize a hydroxylated UiO-66 dye adsorbent. This material exhibits good hydrothermal stability and acid and alkali resistance, and can be reused simply by solvent washing. It can effectively adsorb the organic dye methylene blue from water.

[0005] Chinese patent CN115636950A discloses a method for preparing ZIF-8 hierarchical porous materials and their applications. This method uses ZIF-8 as a precursor and controls the pore size of the material by adjusting the concentration of the surfactant, reaction time, and reaction temperature. This method can prepare ZIF-8 with a pore size range of 0.4-200 Å, and its adsorption capacity is increased by approximately 1.8 times compared to the original state.

[0006] Although MOFs materials have good adsorption properties, they are currently only used in water and soil environments. This makes it difficult to recycle the adsorbents after adsorption, reducing their recyclability and increasing their cost. Summary of the Invention

[0007] The purpose of this invention is to provide an iron-doped ZIF-67-derived magnetic Fe-Co-C composite material, its preparation method, and its application. By imparting magnetism to the adsorbent material, this invention solves the problem of the difficulty in recycling the adsorbent material in aquatic and soil environments, increases the recovery rate of the adsorbent material, and reduces the cost of use.

[0008] The objective of this invention is achieved as follows:

[0009] A method for preparing an iron-doped ZIF-67-derived magnetic Fe-Co-C composite material includes the following steps:

[0010] (1) Take chitosan, ZIF-67 and ferric chloride and dissolve them in 2% acetic acid solution. After stirring, centrifuge and wash with ethanol, then put them in an oven to dry overnight to obtain sample A;

[0011] (2) Sample A was carbonized in a tube furnace filled with nitrogen to obtain sample B;

[0012] (3) Sample B was further carbonized in a muffle furnace to obtain an iron-doped ZIF-67-derived magnetic Fe-Co-C composite material.

[0013] The present invention discloses a method for preparing an iron-doped ZIF-67-derived magnetic Fe-Co-C composite material. This method involves adding ferric chloride to ZIF-67 and then carbonizing it, thereby imbuing it with magnetic properties and dye adsorption capacity. The adsorption capacity can reach approximately four times that of the raw ZIF-67, representing a significant improvement. Furthermore, the preparation method is simple to operate, and the iron element is more evenly distributed, making the magnetic recovery of the adsorbed material easier and solving the technical problem of the difficulty in recovering MOF-derived materials in aquatic and soil environments.

[0014] As a further improvement of the present invention, in step (1), the mass ratio of chitosan, ZIF-67 and ferric chloride is 1:(0.2-0.5):(0.1-0.18), which ensures that the obtained adsorbent material has a better adsorption effect.

[0015] As a further improvement of the present invention, in step (1), the mass ratio of chitosan, ZIF-67 and ferric chloride is 1:0.37:0.139 to obtain the best adsorption effect.

[0016] As a further improvement of the present invention, in step (1), the 2% acetic acid solution containing chitosan, ZIF-67 and ferric chloride needs to be stirred for 3-5 hours to ensure that the materials are mixed evenly and that the iron element is evenly distributed, which helps to form good magnetism.

[0017] As a further improvement of the present invention, in step (1), the mixed solution after stirring is washed with ethanol 3-5 times after centrifugation to remove excess acetic acid solution and ensure the synthesis effect.

[0018] As a further improvement of the present invention, in step (2), the tube furnace is heated to 900 ℃ at a rate of 2-5 ℃ / min and maintained for 3 h, and then naturally cooled to room temperature, so that the iron and cobalt elements in the material are oxidized, ensuring that the material has good magnetic properties.

[0019] As a further improvement of the present invention, in step (3), the muffle furnace is heated to 400 ℃ at a rate of 2-5 ℃ / min and maintained for 2 h, then naturally cooled to room temperature, and a second annealing is performed to remove excess carbon elements, thereby further improving the magnetic properties of the material.

[0020] The present invention also provides an iron-doped ZIF-67-derived magnetic Fe-Co-C composite material prepared according to the above preparation method. The composite material is mainly microporous with a small number of mesopores and macropores, which enhances the adsorption capacity of the material. At the same time, the material is magnetic, and with the help of an external magnetic field, it effectively enhances the material's ability to separate from the environmental medium, solves the technical problem of the material being difficult to recycle, facilitates recycling, and reduces the cost of use.

[0021] This invention also provides the application of the aforementioned iron-doped ZIF-67-derived magnetic Fe-Co-C composite material, which is used to adsorb dyes. Further, the dye is Congo Red. Experiments have shown that this composite material can adsorb wastewater containing Congo Red dye and can be recycled and reused, demonstrating promising industrial applications in wastewater dye adsorption. Attached Figure Description

[0022] Figure 1 The images show scanning electron microscope (SEM) and scanning electron microscopy (EDS) images of the iron-doped ZIF-67-derived magnetic Fe-Co-C composite material prepared in Example 1 of this invention.

[0023] Figure 2 The image shows the X-ray diffraction (XRD) pattern of the iron-doped ZIF-67-derived magnetic Fe-Co-C composite material prepared in Example 1 of this invention.

[0024] Figure 3 This is a pore size distribution diagram of the iron-doped ZIF-67-derived magnetic Fe-Co-C composite material prepared in Example 1 of the present invention.

[0025] Figure 4 This is the adsorption isotherm of Congo red dye for the iron-doped ZIF-67-derived magnetic Fe-Co-C composite material prepared in Example 1 of the present invention.

[0026] Figure 5This is a magnetic effect diagram of the iron-doped ZIF-67-derived magnetic Fe-Co-C composite material prepared in Example 1 of the present invention.

[0027] Figure 6 The hysteresis loop is the magnetic hysteresis loop of the iron-doped ZIF-67-derived magnetic Fe-Co-C composite material prepared in Example 1 of this invention.

[0028] Figure 7 This table compares the BET specific surface area and adsorption capacity of the iron-doped ZIF-67-derived magnetic Fe-Co-C composite materials prepared in Examples 1, 2, and 3 of this invention with that of the raw material ZIF-67. Implementation

[0029] To more clearly demonstrate the technical solution and its effects provided by the present invention, the following detailed description of the iron-doped ZIF-67-derived magnetic Fe-Co-C composite material, its preparation method, and its application are provided by specific embodiments. Example

[0030] (1) Take 0.25 g chitosan, 0.0625 g ZIF-67 and 0.0347 g ferric chloride (mass ratio of 1:0.37:0.139) and dissolve them in 25 ml of 2% acetic acid solution and stir for 3 h. Then evaporate the water by solution evaporation, centrifuge and wash with ethanol 3 times. The product is dried in an oven overnight to obtain sample A.

[0031] (2) Place the ceramic boat containing sample A in a tube furnace under a nitrogen atmosphere, raise the temperature to 900 ℃ at a rate of 2 ℃ / min, maintain for 3 h, and allow to cool naturally to room temperature to obtain sample B.

[0032] (3) Place the crucible containing sample B into a muffle furnace in an air atmosphere, raise the temperature to 400 ℃ at a heating rate of 2 ℃ / min, maintain for 2 h, and allow to cool naturally to room temperature to obtain the finished product.

[0033] The morphology and properties of the iron-doped ZIF-67-derived magnetic Fe-Co-C composite material prepared in Example 1 were tested as follows:

[0034] 1. The Fe-Co-C composite material prepared in Example 1 was observed using scanning electron microscopy and elemental distribution analysis. Figure 1 (a) and Figure 1 (b) It can be seen that the Fe-Co-C composite material prepared in Example 1 of the present invention is a sphere with a particle size of about 250 nm, and there are irregular attachments on it. Figure 1(c) is an elemental distribution diagram of the Fe-Co-C composite material prepared in Example 1 of the present invention, showing the elemental distribution of C, N, O, Co and Fe. It can be seen that the material is rich in Fe and Co elements and the elements are evenly distributed, which is conducive to forming good magnetism and also conducive to recycling through a magnetic field.

[0035] 2. The Fe-Co-C composite material prepared in Example 1 was observed using an X-ray diffractometer, and the results were as follows: Figure 2 The X-ray diffraction pattern shown indicates that the main peak of the Fe-Co-C composite material is at 44.7°, proving that the material is mainly composed of Fe and Co elements, which is conducive to the formation of good magnetism.

[0036] 3. Nitrogen adsorption experiments were conducted on the Fe-Co-C composite material prepared in Example 1 using a BET physical adsorption analyzer, and the results were as follows: Figure 3 The aperture distribution diagram shown is from... Figure 3 It can be seen that the pore structure of the Fe-Co-C composite material is mainly composed of micropores, with some mesopores and macropores. The presence of mesopores and macropores provides channels for dye adsorption, thereby enhancing the adsorption capacity of the material.

[0037] 4. Using the Fe-Co-C composite material prepared in Example 1 as the adsorbent, adsorption kinetics experiments were conducted on Congo red, and the Congo red content was determined by ultraviolet spectrophotometry to obtain the adsorption capacity of the adsorbent for Congo red. Specifically: a 400 mg / L Congo red solution was prepared, and 10 mL portions of 400 ppm Congo red solution were taken. Then, 10 mg of the Fe-Co-C material prepared in Example 1 was added to each portion of the solution as the adsorbent. Timing was initiated immediately after adding the adsorbent, and the mixture was continuously shaken at 25 °C. Then, at time points of 5 min, 10 min, 20 min, 30 min, 60 min, 90 min, 120 min, 180 min, 240 min, 480 min, and 720 min, portions of liquid were transferred from the 10 portions of the mixture and centrifuged. The collected liquids were labeled, and the concentrations of these Congo red solutions at different time points were measured by ultraviolet spectrophotometry to obtain the adsorption capacity of the adsorbent. Figure 4 The diagram shows the adsorption kinetics of Congo red in water at different time points. Figure 4 It can be seen that the Fe-Co-C composite material prepared in Example 1 reaches adsorption saturation for Congo red in about 7 hours, confirming that the material has the ability to adsorb Congo red dye. The maximum adsorption capacity of this material for Congo red dye was obtained by fitting and recorded as 200.8 mg / g. Figure 7 Table. Compared with the raw material ZIF-67, the Fe-Co-C composite material prepared in Example 1 showed a 4.22-fold increase in adsorption capacity for Congo red.

[0038] 5. Use a magnet to test the magnetic strength of the Fe-Co-C composite material prepared in Example 1, such as... Figure 5 As shown, the material has good magnetic properties and can be easily attracted to the inner wall of a glass container by a magnet, thus achieving the purpose of recycling.

[0039] 6. The Fe-Co-C composite material prepared in Example 1 was tested using a vibrating sample magnetometer, and the results were as follows: Figure 6 The hysteresis loop shown. (By...) Figure 6 It can be seen that the hysteresis loop of the Fe-Co-C composite material prepared in Example 1 has the characteristics of low coercivity and low remanence, which is consistent with the characteristics of soft magnetic materials. The saturation magnetization of the Fe-Co-C composite material is 85.4 emug-1, indicating that the material has good magnetism and is beneficial for recycling. Example

[0040] (1) Take 0.25 g chitosan, 0.0925 g ZIF-67 and 0.025 g ferric chloride and dissolve them in 25 ml of 2% acetic acid solution and stir for 4 h. Then evaporate the water by solution evaporation, centrifuge and wash with ethanol 4 times. The product is dried in an oven overnight to obtain sample A.

[0041] (2) Place the ceramic boat containing sample A in a tube furnace under a nitrogen atmosphere, raise the temperature to 900 ℃ at a rate of 5 ℃ / min, maintain for 3 h, and allow to cool naturally to room temperature to obtain sample B.

[0042] (3) Place the crucible containing sample B into a muffle furnace in an air atmosphere, raise the temperature to 400°C at a rate of 5°C / min, maintain for 2 h, and allow to cool naturally to room temperature to obtain the finished product.

[0043] The morphology and properties of the Fe-Co-C composite material prepared in Example 2 were tested, and there was no significant difference between the morphology and properties of the product and the Fe-Co-C composite material prepared in Example 1.

[0044] Kinetic tests were conducted on the Fe-Co-C composite material prepared in Example 2 for Congo red dye (experimental conditions were the same as in Example 1). The results showed that the Fe-Co-C composite material prepared in Example 2 reached adsorption saturation for Congo red within 8 hours, confirming the material's adsorption capacity for Congo red dye. The maximum adsorption capacity of this material for Congo red dye was obtained through fitting, and recorded as 183.9 mg / g. Figure 7 Table. Compared with the raw material ZIF-67, the Fe-Co-C composite material prepared in Example 2 showed a 3.86-fold increase in adsorption capacity for Congo red. Example

[0045] (1) Take 0.25 g chitosan, 0.125 g ZIF-67 and 0.045 g ferric chloride and dissolve them in 25 ml of 2% acetic acid solution and stir for 5 h. Then evaporate the water by solution evaporation, centrifuge and wash with ethanol 5 times. The product is dried in an oven overnight to obtain sample A.

[0046] (2) Place the ceramic boat containing sample A in a tube furnace under a nitrogen atmosphere, raise the temperature to 900 ℃ at a rate of 4 ℃ / min, maintain for 3 h, and allow to cool naturally to room temperature to obtain sample B.

[0047] (3) Place the crucible containing sample B into a muffle furnace in an air atmosphere, raise the temperature to 400 ℃ at a heating rate of 4 ℃ / min, maintain for 2 h, and allow to cool naturally to room temperature to obtain the finished product.

[0048] The morphology and properties of the Fe-Co-C composite material prepared in Example 3 were tested, and there was no significant difference between the morphology and properties of the product and the Fe-Co-C composite material prepared in Example 1.

[0049] Kinetic tests were conducted on the Fe-Co-C composite material prepared in Example 3 for Congo red dye (experimental conditions were the same as in Example 1). The results showed that the Fe-Co-C composite material prepared in Example 3 also reached adsorption saturation for Congo red within 8 hours, confirming the material's adsorption capacity for Congo red dye. The maximum adsorption capacity of this material for Congo red dye was obtained through fitting, and recorded as 176.1 mg / g. Figure 7 Table. Compared with the raw material ZIF-67, the Fe-Co-C composite material prepared in Example 3 showed a 3.70-fold increase in adsorption capacity for Congo red.

[0050] This invention is not limited to the above embodiments. Based on the technical solutions disclosed in this invention, those skilled in the art can make some substitutions and modifications to some of the technical features without creative effort, and all such substitutions and modifications are within the protection scope of this invention.

Claims

1. A method for preparing an iron-doped ZIF-67 derived magnetic Fe-Co-C composite material, characterized in that, Includes the following steps: (1) Take chitosan, ZIF-67 and ferric chloride and dissolve them in 2% acetic acid solution. After stirring, centrifuge and wash with ethanol, then put them in an oven to dry overnight to obtain sample A; (2) Sample A was carbonized in a tube furnace filled with nitrogen to obtain sample B; (3) Sample B was further carbonized in a muffle furnace to obtain an iron-doped ZIF-67-derived magnetic Fe-Co-C composite material; In step (1), the mass ratio of chitosan, ZIF-67, and ferric chloride is 1: (0.2-0.5): (0.1-0.18); In step (2), the tubular furnace is heated to 900 ℃ at a rate of 2-5 ℃ / min and maintained for 3 h, then naturally cooled to room temperature; In step (3), the muffle furnace is heated to 400 ℃ at a rate of 2-5 ℃ / min and maintained for 2 h, and then naturally cooled to room temperature.

2. The method for preparing the iron-doped ZIF-67 derived magnetic Fe-Co-C composite material according to claim 1, characterized in that: In step (1), the mass ratio of chitosan, ZIF-67 and ferric chloride is 1:0.37:0.

139.

3. The method for preparing the iron-doped ZIF-67 derived magnetic Fe-Co-C composite material according to claim 1, characterized in that: In step (1), the 2% acetic acid solution containing chitosan, ZIF-67, and ferric chloride needs to be stirred for 3-5 hours.

4. The method for preparing the iron-doped ZIF-67 derived magnetic Fe-Co-C composite material according to claim 1, characterized in that: In step (1), the mixed solution after stirring should be washed with ethanol 3-5 times after centrifugation.

5. An iron-doped ZIF-67-derived magnetic Fe-Co-C composite material, characterized in that: It is prepared according to any one of claims 1 to 4.

6. The application of the iron-doped ZIF-67 derived magnetic Fe-Co-C composite material according to claim 5, characterized in that: Iron-doped ZIF-67-derived magnetic Fe-Co-C composite materials were used for dye adsorption.

7. The application of the iron-doped ZIF-67 derived magnetic Fe-Co-C composite material according to claim 6, characterized in that: The dye is Congo Red.

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