A method for synthesizing a nano-porous spheroidal hematite

Abstract

The application discloses a kind of synthesis methods of nano-porous spherical hematite.The application uses FeCl3·6H2O as reaction raw material, the concentration of FeCl3 is 0.03~0.1 mol / L, reaction solvent is 90%~98% ethanol solution in volume concentration, in the range of 180~230 ℃, hydrothermal reaction is carried out for 0.5~18h, the solid precipitate obtained by centrifugation after reaction kettle is cooled to room temperature is washed, dried, and nano-porous spherical hematite is obtained.The nano-porous spherical hematite prepared by the application has smaller pores and larger specific surface area on the surface, improves the adsorption performance of hematite, and can improve the adsorption efficiency of organic pollutants.

Description

Technical Field

[0001] This invention relates to a method for synthesizing nanoporous spherical hematite, belonging to the field of mineral materials technology. Background Technology

[0002] Hematite, a common iron oxide, is widely found in the basic components of Earth's systems, including the atmosphere, pedosphere, and biosphere. Different types of hematite have different physicochemical properties and are widely used in pigments, catalytic materials, pharmaceutical materials, gas adsorption, and water purification materials.

[0003] Nano-sized hematite exhibits good adsorption properties for heavy metals and organic pollutants in nature, possessing advantages such as wide adsorption range, large capacity, high efficiency, and recyclability. This is due to the smaller particle size and larger specific surface area of ​​nano-sized hematite. Different crystal facet types of hematite have varying adsorption efficiencies. Therefore, many different methods for synthesizing hematite have been developed, such as a nanoporous hematite catalyst and its preparation method (application number: 202111050200.4); a method for synthesizing trigonal metahedral twin crystals of hematite (application number: 202011471573.4); a method for manufacturing granular hematite microparticles (application number: 02108153.0); and a method for preparing hematite nanocubes (…). Applications include: a method for growing hematite pellets (application number: 200410035715.7); a method for preparing submicron hematite particles (application number: 201610093693.2); a method for synthesizing porous hematite nanorod arrays (application number: 201810488271.4); and a method for preparing hematite oxide pellets (application number: 201710170771.9). It can be seen that the morphology and size of nano-hematite materials have a significant impact on their adsorption performance. Furthermore, different morphologies of hematite can be synthesized using various chemical reagents under different reaction conditions. Therefore, the synthesis and performance of hematite nanostructures with different morphologies have attracted widespread attention. However, there are currently no reports on the green synthesis of porous nano-spherical hematite. Summary of the Invention

[0004] The purpose of this invention is to provide a method for synthesizing nanoporous spherical hematite, which is a one-step hydrothermal synthesis method. This invention further enriches the methods for synthesizing hematite, and the process is simple and environmentally friendly.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for synthesizing nanoporous spherical hematite includes the following steps:

[0007] Step 1: Measure anhydrous ethanol, add deionized water, and prepare an ethanol solution.

[0008] Step 2: Weigh FeCl3·6H2O, add it to an ethanol solution, place it in a reaction flask, and stir with a magnetic stirrer until completely dissolved.

[0009] Step 3: Place the FeCl3·6H2O solution in a reaction vessel and carry out a hydrothermal reaction in an oven. After the reaction vessel cools to room temperature, wash the generated solid material with deionized water, centrifuge it, and finally dry it to obtain nanoporous spherical hematite.

[0010] Furthermore, the ethanol solution in step 1 is prepared by mixing anhydrous ethanol and deionized water to prepare an ethanol solution with a volume concentration of 90% to 98%. In some exemplary embodiments of the present invention, 144 mL of anhydrous ethanol solution and 6 mL of deionized water are measured to prepare 150 mL of ethanol solution with a volume concentration of 96%.

[0011] Furthermore, the concentration of FeCl3·6H2O in step 2 is 0.03~0.1 mol / L.

[0012] Furthermore, the reaction flask in step 2 is a sealable glass bottle.

[0013] Furthermore, the FeCl3·6H2O solution in step 3 is obtained by completely dissolving ferric chloride powder in an ethanol solution under magnetic stirring.

[0014] Furthermore, the hydrothermal reaction temperature in step 3 is 180℃~230℃, and the reaction time is 0.5~18 h. Preferably, the reaction time is 1.5~6 h.

[0015] Furthermore, the deionized water washing in step 3 involves discarding the supernatant after the reaction, washing with deionized water, and then centrifuging again. This step is repeated 3 to 10 times.

[0016] Furthermore, the drying in step 3 is carried out in an oven at a temperature of 40 ℃ to 60 ℃.

[0017] This invention utilizes ferric chloride and ethanol solution to prepare FeCl3·6H2O solution, and then generates a nanoporous spherical hematite through hydrothermal reaction.

[0018] Compared with the prior art, the beneficial results of the present invention are:

[0019] The method for synthesizing nanoporous spherical hematite provided by this invention is a one-step hydrothermal reaction method, which does not require any extra chemical reagents, is simple to operate in the laboratory, is green and environmentally friendly, and can be produced in large quantities.

[0020] The specific surface area of ​​conventional hematite is generally between 1 and 30 m². 2 The nanoporous spherical hematite prepared by this invention has a smaller pore size and a larger specific surface area, with a pore diameter of approximately 0.48 ± 0.1 μm and a specific surface area of ​​72.46 m². 2 / g. This is beneficial for improving the adsorption efficiency of hematite for organic matter, and has potential application value in the treatment and degradation of organic wastewater. Attached Figure Description

[0021] Figure 1 The XRD pattern of nanoporous spherical hematite.

[0022] Figure 2 The image is a scanning electron microscope image of the 200 nm resolution porous spherical hematite prepared in Example 1.

[0023] Figure 3 The image is a scanning electron microscope (SEM) image of the 200 nm resolution porous spherical hematite prepared in Example 3.

[0024] Figure 4 The image shown is a scanning electron microscope image of the 200 nm resolution spherical hematite nanoparticles prepared in Example 4.

[0025] Figure 5 The adsorption efficiency curve of methylene blue on the nanoporous spherical hematite prepared in Example 1 is shown. Detailed Implementation Example 1

[0026] (1) Preparation of ethanol solution: First, measure 144 mL of ethanol solution, add 6 mL of deionized water solution, and prepare 150 mL of 96% ethanol solution and place it in the reaction flask.

[0027] (2) Weigh 1.21 g of FeCl3·6H2O, add it to 150 mL of 96% ethanol solution, stir until completely dissolved, and prepare a 0.03 mol / L FeCl3·6H2O solution.

[0028] (3) Place 12 mL of ferric chloride solution in a high-pressure reactor and react in an oven at 180℃ for 6 h with a heating rate of 5℃ / min. After the reaction is complete, cool to room temperature, discard the supernatant, centrifuge, wash with deionized water, centrifuge again, discard the supernatant, and repeat the above steps 3 times. Dry at 40℃ to obtain nanoporous spherical hematite. The hematite yield is 0.048 mol / L and 7.66 g / L, with a synthesis efficiency of 95%. The XRD pattern of the product is shown in [reference needed]. Figure 1 The electron microscopy was performed at a resolution of 200 nm, and the results are shown in [Figure number missing]. Figure 2 .like Figure 2 The scanning electron microscope images shown indicate that the obtained sample has a regular spherical morphology, and many nanopores can be clearly seen on the sample surface, indicating that we have successfully prepared nanoporous spherical hematite using this method.

[0029] Using Nano Measurer 1.2 software, porous sphere samples were selected from scanning electron microscopes to measure the average pore size of the porous spheres and the size of the nanoparticles. The specific surface area of ​​the sample was measured using the nitrogen adsorption method (BET), which yielded a specific surface area of ​​72.46 m². 2 / g, pore size 0.48±0.1μm, particle size 41.32±2nm. Example 2

[0030] 12 mL of the ferric chloride solution prepared in Example 1 was placed in a high-pressure reactor and reacted in an oven at 180°C for 0.5 h at a heating rate of 5°C / min. After the reaction was completed, the mixture was cooled to room temperature, the supernatant was discarded, and the mixture was centrifuged and washed with deionized water. The supernatant was discarded after centrifugation again. The above steps were repeated 3 times. The mixture was dried at 40°C to obtain a product with an irregular elongated shape. No nanoporous spherical hematite was obtained. Example 3

[0031] 12 mL of the ferric chloride solution prepared in Example 1 was placed in a high-pressure reactor and reacted in an oven at 180°C for 1.5 h at a heating rate of 5°C / min. After the reaction was complete, the solution was cooled to room temperature, the supernatant was discarded, and the solution was centrifuged and washed with deionized water. The process was repeated three times. The solution was then dried at 40°C and observed using an electron microscope with a resolution of 200 nm. The results are shown in the figure. Figure 3 It can be seen that the obtained sample has a regular sphere morphology and many nanopores. Example 4

[0032] (1) Preparation of ethanol solution: First, measure 135 mL of ethanol solution, add 15 mL of deionized water solution, and prepare 150 mL of 90% ethanol solution and place it in the reaction flask.

[0033] (2) Weigh 1.21 g of FeCl3·6H2O, add it to 150 mL of 90% ethanol solution, stir until completely dissolved, and prepare a 0.03 mol / L FeCl3·6H2O solution.

[0034] (3) Place 12 mL of ferric chloride solution in a high-pressure reactor and react in an oven at 180℃ for 6 h with a heating rate of 5℃ / min. After the reaction is complete, cool to room temperature, discard the supernatant, centrifuge, wash with deionized water, centrifuge again, discard the supernatant, and repeat the above steps 3 times. Dry at 40℃ to obtain a spherical product. Perform electron microscopy with a resolution of 200 nm to observe the results. See below. Figure 4 . Figure 4 The scanning electron microscope images shown indicate that the obtained sample surface is relatively smooth and almost devoid of pores. Comparative Example 1

[0035] (1) Preparation of ethanol solution: First, measure 120 mL of ethanol solution, add 30 mL of deionized water solution, and prepare 150 mL of 80% ethanol solution and place it in the reaction flask.

[0036] (2) Weigh 4.05 g of FeCl3·6H2O, place it in 150 mL of 80% ethanol solution, stir until completely dissolved, and prepare a 0.1 mol / L FeCl3·6H2O solution.

[0037] (3) Take 12 mL of ferric chloride solution and place it in a high-pressure reactor. Place it in a 230 ℃ oven and react for 0.5 h. The heating rate is 5 ℃ / min. After the reaction is complete, cool it to room temperature, discard the supernatant, centrifuge and wash with deionized water. Centrifuge again and discard the supernatant. Repeat the above steps 10 times. Dry at 60 ℃ to obtain the product with the morphology of rods of different lengths. No nanoporous spherical hematite was obtained. Comparative Example 2

[0038] (1) Preparation of ethanol solution: First, measure 120 mL of ethanol solution, add 30 mL of deionized water solution, and prepare 150 mL of 80% ethanol solution and place it in the reaction flask.

[0039] (2) Weigh 1.21 g of FeCl3·6H2O, add it to 150 mL of 80% ethanol solution, stir until completely dissolved, and prepare a 0.03 mol / L FeCl3·6H2O solution.

[0040] (3) Take 12 mL of ferric chloride solution and place it in a high-pressure reactor. Place it in an oven at 180℃ and react for 6 h. The heating rate is 5℃ / min. After the reaction is complete, cool it to room temperature, discard the supernatant, centrifuge and wash with deionized water. Centrifuge again and discard the supernatant. Repeat the above steps 3 times. Dry it at 40℃. The morphology of the product is dense needle-like. No nanoporous spherical hematite was obtained.

[0041] The adsorption efficiency of methylene blue (MB) on nanoporous ellipsoidal hematite prepared in Example 1 was studied by kinetic adsorption. The experimental solution volume was 70 mL, the MB concentration was 5 mg / L, and the adsorbent was 2 g / L nanoporous ellipsoidal hematite. The absorption spectra of the supernatant at different time points were measured using a 4802 UV-Vis double-beam spectrophotometer. The absorption wavelength of MB was 665 nm. The results are as follows: Figure 5 As shown, the removal rate reached 50% after 15 minutes, and 87.8% after adsorption saturation.

[0042] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A method for synthesizing nanoporous spherical hematite, characterized in that, Includes the following steps: FeCl3·6H2O was dissolved in an ethanol solution to obtain a FeCl3·6H2O ethanol reaction solution; the reaction was carried out at a hydrothermal reaction temperature of 180℃~230℃ for 1.5~6h, filtered, washed, and dried to obtain nanoporous spherical hematite; the ethanol solution was prepared by mixing anhydrous ethanol and deionized water to prepare an ethanol solution with a volume concentration of 96%.

2. The method for synthesizing nanoporous spherical hematite according to claim 1, characterized in that, The molar concentration of FeCl3·6H2O in the FeCl3·6H2O ethanol reaction solution is 0.03~0.1 mol / L.

3. The method for synthesizing nanoporous spherical hematite according to claim 1, characterized in that, The drying process is oven drying, with a drying temperature of 40~60 ℃.

4. A nanoporous spherical hematite prepared by the method described in any one of claims 1-3.

5. The nanoporous spherical hematite according to claim 4, characterized in that, The specific surface area of ​​the nanoporous spherical hematite is greater than 70m². 2 / g.

6. An application of the nanoporous spherical hematite as described in claim 4, characterized in that, The nanoporous spherical hematite is used for the adsorption of organic pollutants.

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