Preparation Method of Magnetic Fluorescent Graphene

Abstract

The present invention belongs to the technical field of inorganic nanomaterials, and particularly relates to a preparation method of magnetic fluorescent graphene. Magnetic grinding is carried out on flake graphite and stainless steel needles to obtain magnetic graphene; magnetic graphene, concentrated nitric acid and concentrated sulfuric acid are subjected to an oxidation reaction to obtain a mixed solution; the mixed solution is subjected to ultrasonic treatment and calcination to obtain magnetic graphene oxide; the magnetic graphene oxide is dissolved in deionized water, filtered by suction and dialyzed to obtain a magnetic fluorescent graphene solution; the magnetic fluorescent graphene solution is freeze-dried to obtain magnetic fluorescent graphene. The preparation process of the present invention is simple, does not generate too much waste acid, and has less environmental pollution; in the process of obtaining magnetism, no magnetic material reaction needs to be added, and no fluorescent material needs to be added to make it fluorescent.

Description

Technical Field

[0001] The present invention belongs to the technical field of inorganic nanomaterials, and particularly relates to a preparation method of magnetic fluorescent graphene. Background Art

[0002] Graphene is a single-layer carbon atom plane material peeled from graphite materials. The thickness of this two-dimensional graphite crystal film is only one carbon atom thick, and its strength is 100 times that of steel. Graphene has excellent optical, electrical, and mechanical properties, and has important application prospects in materials science, micro-nano processing, energy, biomedicine, and drug delivery, etc., and is considered a revolutionary material in the future. It is currently the material with the fastest room-temperature conductivity, the greatest mechanical strength, and the strongest heat conduction ability.

[0003] The fluorescence characteristics of graphene make the application fields of graphene more extensive. For example, it has great potential in the biomedical field, and fluorescent graphene is widely used in molecular detection, disease diagnosis, cell imaging, etc.

[0004] The commonly used preparation method of magnetic graphene oxide is to react graphene with rare earth materials or magnetic materials to obtain a new monolayer graphene material with magnetism. During the preparation process, the material ratio is relatively complex and the production efficiency is low.

[0005] Chinese Patent CN103127910A discloses a magnetic graphene, a preparation method and its uses. Graphite oxide and iron(III) acetylacetonate are dispersed in a mixed solvent of ethylenediamine / water with a volume ratio of 9:1, ultrasonically dispersed, and then the mixed solution is transferred to a high-pressure reaction kettle lined with polytetrafluoroethylene for reaction. After the reaction, the obtained solid is washed with water and ethanol multiple times, and then the product is collected with a magnet and dried to obtain magnetized graphene. The preparation process of this patent is complex and waste liquid is easily generated during the preparation process.

[0006] Chinese Patent CN106084232A discloses a preparation and application of a fluorescent magnetic graphene oxide-based 4-chlorophenol molecularly imprinted polymer. This molecularly imprinted polymer is prepared by compounding graphene oxide with a magnetic material, then modifying fluorescent quantum dots on its surface, and finally preparing a fluorescent magnetic graphene oxide-based 4-chlorophenol molecularly imprinted polymer with specific recognition ability for 4-chlorophenol template molecules through molecular imprinting technology. The preparation process of this patent is complex, and the fluorescence and magnetism need to be provided by external materials, and the composition is complex.

[0007] At present, there is an urgent need to provide a preparation method of magnetic fluorescent graphene with a simple preparation process, high production efficiency, no excessive waste acid generation, and less environmental pollution. Summary of the Invention

[0008] The object of the present invention is to provide a preparation method of magnetic fluorescent graphene, the preparation process is simpler, the production efficiency is higher, there will be no excessive waste acid generated, and the preparation process has less environmental pollution.

[0009] The preparation method of magnetic fluorescent graphene described in the present invention is to perform magnetic grinding on flake graphite and stainless steel needles to obtain magnetic graphene; magnetic graphene, concentrated nitric acid and concentrated sulfuric acid are subjected to an oxidation reaction to obtain a mixed solution; the mixed solution is subjected to ultrasonic treatment and calcination to obtain magnetic graphene oxide; the magnetic graphene oxide is dissolved in deionized water, filtered by suction, and dialyzed to obtain a magnetic fluorescent graphene solution; the magnetic fluorescent graphene solution is freeze-dried to obtain magnetic fluorescent graphene.

[0010] The mass ratio of the flake graphite to the stainless steel needles is 1:10 - 60.

[0011] The mesh number of the flake graphite is 30 - 400 mesh.

[0012] The size of the stainless steel needles is Φ: 0.3 - 3.0 mm, L: 2 - 30 mm.

[0013] The time of the magnetic grinding is 8 - 50 h.

[0014] The ratio of the magnetic graphene to the concentrated nitric acid is 1:15 - 80, wherein the magnetic graphene is in g and the concentrated nitric acid is in ml.

[0015] The volume ratio of the concentrated nitric acid to the concentrated sulfuric acid is 3 - 4:1.

[0016] The time of the oxidation reaction is 6 - 30 h.

[0017] The ultrasonic time is 0.5 - 15 h, and the ultrasonic frequency is 40 - 60 KHz.

[0018] The calcination temperature is 300 - 350 °C, and the calcination time is 15 - 20 min.

[0019] The ratio of the magnetic graphene oxide to the deionized water is 1:20 - 50, wherein the magnetic graphene oxide is in g and the deionized water is in ml.

[0020] The suction filtration is carried out through two layers of filter paper.

[0021] The dialysis time is 3 - 5 d.

[0022] The preparation method of magnetic fluorescent graphene described in the present invention includes the following steps:

[0023] (1) Put the flake graphite and the stainless steel needles into the grinding reaction tank of the grinding reaction device for magnetic grinding;

[0024] (2) After the grinding is completed, it is cooled to room temperature to obtain a mixture of magnetic nanographite sheets and stainless steel needles. The mixture of magnetic nanographite sheets and stainless steel needles is added to deionized water to separate the stainless steel needles, and an aqueous solution of magnetic nanographite sheets is obtained.

[0025] (3) The aqueous solution of magnetic nanographite sheets is stirred and magnetically separated with a magnet to obtain magnetic nanographite sheets.

[0026] (4) After the magnetic nanographite sheets are dried in an oven and ground into powder, magnetic graphene is obtained.

[0027] (5) Magnetic graphene, concentrated nitric acid and concentrated sulfuric acid are subjected to an oxidation reaction to obtain a mixed solution.

[0028] (6) The mixed solution is placed in an ultrasonic cleaner for ultrasonic treatment.

[0029] (7) The ultrasonic-treated mixed solution is calcined in a tube furnace to obtain magnetic graphene oxide.

[0030] (8) The magnetic graphene oxide is dissolved in deionized water, filtered through two layers of filter paper, and the filtrate is obtained. Then, the filtrate is dialyzed with a dialysis bag to obtain a magnetic fluorescent graphene solution. The magnetic fluorescent graphene solution is freeze-dried to obtain magnetic fluorescent graphene.

[0031] The grinding reaction device described in step (1) includes a grinding reaction tank and a base. A concave space is opened at the top of the base, and a magnetic field generating electromechanical device is installed in the concave space. The magnetic field generating electromechanical device includes silicon steel sheets and coil windings wound around the silicon steel sheets. The silicon steel sheets are vertically and evenly arranged in the concave space. A steel plate sheath is installed at the central position of the magnetic field generating electromechanical device. The grinding reaction tank is placed inside the steel plate sheath, and the bottom of the grinding reaction tank is connected to the bottom of the concave space. A window is opened in the middle of the base, and a fan is installed at the bottom of the window for heat dissipation of the magnetic field generating electromechanical device. A sealing cover and a heat exchange device are provided on the grinding reaction tank, and sealing pressure resistance or heat exchange can be achieved as required. A thermocouple sensing device and an atmosphere control device are connected to the top of the sealing cover. A pressure gauge is installed on the atmosphere control device. The atmosphere control device is a gas pipe opening and a gas valve, which can be connected to an external gas cylinder to adjust the pressure. The bottom of the grinding reaction tank is connected to the base, and the grinding reaction tank is surrounded by electromagnets. The electromagnets are composed of electromagnetic coils and iron cores. Three-phase electricity generates an alternating magnetic field. By using electromagnets, the magnetic field intensity and the magnetic field rotation frequency can be adjusted to meet the needs of chemical reactions.

[0032] The frequency of the grinding reaction device described in step (1) is 40 - 60 Hz, and the magnetic field intensity of the grinding reaction device is 0.15 - 0.2 T.

[0033] In step (1), stop for 10 minutes every 1 hour of grinding. The longer the grinding time, the better the magnetism of the ground graphite.

[0034] In step (8), the pore diameter of the filter paper is 0.3 - 0.5 microns.

[0035] In step (8), the cut-off molecular weight of the dialysis bag is 800 - 1000.

[0036] In step (8), the magnetic fluorescent graphene solution emits blue fluorescence under the irradiation of a 365 nm ultraviolet lamp.

[0037] The beneficial effects of the present invention are as follows:

[0038] The present invention can obtain magnetic graphene through magnetic grinding, and oxidize the magnetic graphene with a mixed solution of concentrated nitric acid and concentrated sulfuric acid. After oxidation, it still has magnetism. Since monolayer graphite is exfoliated by grinding, there are crystalline and amorphous particles smaller than 10 nm on the monolayer graphite. The particles smaller than 10 nm will cause energy level splitting and the emergence of a forbidden band. Under continuous irradiation of ultraviolet light, there will be a suitable ultraviolet light energy, causing a fluorescence effect.

[0039] Compared with the preparation methods of the reaction between graphene and magnetic materials in the prior art, the preparation process of the present invention is simpler and the production efficiency is higher. The preparation process of the present invention is simple, does not produce too much waste acid, and has less environmental pollution. In the process of obtaining magnetism in the present invention, no magnetic material reaction needs to be added, nor does a fluorescent material need to be added to make it fluorescent. Description of the Drawings

[0040] Figure 1 is a schematic structural diagram of the grinding reaction device of the present invention;

[0041] In the figure, 1. steel plate sheath; 2. thermocouple sensing device; 3. sealing cover; 4. atmosphere control device; 5. pressure gauge; 6. coil winding; 7. silicon steel sheet; 8. base; 9. grinding reaction tank; 10. fan; 11. window.

[0042] Figure 2 is a physical picture of the aqueous solution of magnetic nanographite flakes in Example 1.

[0043] Figure 3 is a fluorescence spectrogram of the magnetic fluorescent graphene solution in Example 1 under 365 nm excitation light.

[0044] Figure 4 is a physical picture of the aqueous solution of magnetic nanographite flakes in Example 2.

[0045] Figure 5 is a fluorescence spectrogram of the magnetic fluorescent graphene solution in Example 2 under 365 nm excitation light.

[0046] Figure 6 It is a physical picture of the aqueous solution of magnetic nanographene sheets in Example 3.

[0047] Figure 7 It is a fluorescence spectrogram of the magnetic fluorescent graphene solution in Example 3 under 365 nm excitation light. Detailed implementation manners

[0048] The present invention will be further described below in conjunction with embodiments.

[0049] Example 1

[0050] (1) Weigh 100 g of stainless steel needles with Φ: 1.0 mm and L: 5 mm, and weigh 10 g of 300-mesh flake graphite. Place the weighed flake graphite and stainless steel needles in the grinding reaction tank of the grinding reaction device for magnetic grinding. The magnetic grinding time is 12 h, the frequency of the grinding reaction device is 40 Hz, and the magnetic field strength is 0.15 T. The structural schematic diagram of the grinding reaction device is shown in Figure 1 ;

[0051] (2) After grinding, cool to room temperature to obtain a mixture of magnetic nanographene sheets and stainless steel needles. Add the mixture of magnetic nanographene sheets and stainless steel needles to 500 ml of deionized water, and use a spatula to separate the stainless steel needles to obtain an aqueous solution of magnetic nanographene sheets, as shown in Figure 2 ;

[0052] (3) Stir the aqueous solution of magnetic nanographene sheets and perform magnetic separation with a magnet to obtain magnetic nanographene sheets;

[0053] (4) After drying the magnetic nanographene sheets in an oven and grinding them into powder, magnetic graphene is obtained;

[0054] (5) Perform an oxidation reaction for 15 h with 0.4586 g of magnetic graphene, 30 ml of concentrated nitric acid, and 10 ml of concentrated sulfuric acid to obtain a mixed solution;

[0055] (6) Place the mixed solution in an ultrasonic cleaner and ultrasonicate it for 15 h. The ultrasonic frequency is 40 KHz;

[0056] (7) Place the ultrasonically treated mixed solution in a tube furnace and calcine it at 320 °C for 20 min to dry the acid solution and obtain magnetic oxidized graphene powder;

[0057] (8) Dissolve the obtained magnetic oxidized graphene powder in 50 ml of deionized water, filter it through two layers of 0.5-micron microporous filter paper to obtain a filtrate, and then dialyze the filtrate with a dialysis bag with a molecular weight cut-off of 1000 for 5 d to obtain a magnetic fluorescent graphene solution. The fluorescence spectrogram of the magnetic fluorescent graphene solution under 365 nm excitation light is shown inFigure 3 The magnetic fluorescent graphene solution is freeze-dried to obtain magnetic fluorescent graphene.

[0058] As Figure 1 shown, the grinding reaction device in step (1) includes a grinding reaction tank 9 and a base 8. A concave space is opened at the top of the base 8, and a magnetic field generating electromechanical device is installed in the concave space. The magnetic field generating electromechanical device includes silicon steel sheets 7 and coil windings 6 wound around the silicon steel sheets 7. The silicon steel sheets 7 are vertically and evenly arranged in the concave space. A steel plate sheath 1 is installed at the central position of the magnetic field generating electromechanical device. The grinding reaction tank 9 is placed inside the steel plate sheath 1, and the bottom of the grinding reaction tank 9 is connected to the bottom of the concave space. A window 11 is opened in the middle of the base 8, and a fan 10 is installed at the bottom of the window 11 for heat dissipation of the magnetic field generating electromechanical device. A sealing cover 3 and a heat exchange device are provided on the grinding reaction tank 9, which can achieve sealing and pressure resistance or heat exchange as required. A thermocouple sensing device 2 and an atmosphere control device 4 are connected to the top of the sealing cover 3. A pressure gauge 5 is installed on the atmosphere control device 4. The atmosphere control device 4 is a gas pipe and a gas valve, which can be connected to an external gas cylinder to adjust the pressure. The bottom of the grinding reaction tank 9 is connected to the base 8. The grinding reaction tank 9 is surrounded by electromagnets, which are composed of electromagnetic coils and iron cores. Three-phase electricity generates an alternating magnetic field. By using electromagnets, the magnetic field intensity and the magnetic field rotation frequency can be adjusted to meet the needs of chemical reactions.

[0059] Example 2

[0060] (1) Weigh 100 g of stainless steel needles with Φ: 1.5 mm and L: 7 mm, and weigh 10 g of 300-mesh flake graphite. Place the weighed flake graphite and stainless steel needles in the grinding reaction tank of the grinding reaction device for magnetic grinding. The magnetic grinding time is 10 h, the frequency of the grinding reaction device is 50 Hz, and the magnetic field intensity is 0.16 T. The grinding reaction device is the same as that in Example 1.

[0061] (2) After grinding, cool to room temperature to obtain a mixture of magnetic nanographite flakes and stainless steel needles. Add the mixture of magnetic nanographite flakes and stainless steel needles to 500 ml of deionized water, and use a spatula to separate the stainless steel needles to obtain an aqueous solution of magnetic nanographite flakes, as shown in Figure 4 ;

[0062] (3) Stir the aqueous solution of magnetic nanographite flakes and perform magnetic separation with a magnet to obtain magnetic nanographite flakes.

[0063] (4) After drying the magnetic nanographite flakes in an oven and grinding them into powder, magnetic graphene is obtained.

[0064] (5) Perform an oxidation reaction for 12 h on 0.6651 g of magnetic graphene, 30 ml of concentrated nitric acid, and 10 ml of concentrated sulfuric acid to obtain a mixed solution.

[0065] (6) Put the mixed solution into an ultrasonic cleaner and ultrasonicate for 12 h at an ultrasonic frequency of 50 KHz;

[0066] (7) Put the ultrasonically treated mixed solution into a tube furnace and calcine at 300 °C for 15 min to dry the acidic solution and obtain magnetic graphene oxide powder;

[0067] (8) Dissolve the obtained magnetic graphene oxide powder in 50 ml of deionized water, filter it through two layers of 0.45-μm microporous filter paper to obtain a filtrate, and then dialyze the filtrate with a dialysis bag with a molecular weight cut-off of 1000 for 3 d to obtain a magnetic fluorescent graphene solution. The fluorescence spectrum of the magnetic fluorescent graphene solution under 365-nm excitation light is shown in Figure 5 , and the magnetic fluorescent graphene solution is freeze-dried to obtain magnetic fluorescent graphene.

[0068] Example 3

[0069] (1) Weigh 150 g of stainless steel needles with Φ: 1.5 mm and L: 7 mm, and weigh 10 g of 300-mesh flake graphite. Place the weighed flake graphite and stainless steel needles in the grinding reaction tank of the grinding reaction device for magnetic grinding. The magnetic grinding time is 15 h, the frequency of the grinding reaction device is 60 Hz, the magnetic field strength is 0.2 T, and the grinding reaction device is the same as in Example 1;

[0070] (2) After grinding, cool to room temperature to obtain a mixture of magnetic nanographite flakes and stainless steel needles. Add the mixture of magnetic nanographite flakes and stainless steel needles to 500 ml of deionized water, and use a spatula to separate the stainless steel needles to obtain an aqueous solution of magnetic nanographite flakes, as shown in Figure 6 ;

[0071] (3) Stir the aqueous solution of magnetic nanographite flakes and perform magnetic separation with a magnet to obtain magnetic nanographite flakes;

[0072] (4) After drying the magnetic nanographite flakes in an oven and grinding them into powder, magnetic graphene is obtained;

[0073] (5) Perform an oxidation reaction on 1.9561 g of magnetic graphene, 30 ml of concentrated nitric acid, and 10 ml of concentrated sulfuric acid for 20 h to obtain a mixed solution;

[0074] (6) Put the mixed solution into an ultrasonic cleaner and ultrasonicate for 10 h at an ultrasonic frequency of 60 KHz;

[0075] (7) Put the ultrasonically treated mixed solution into a tube furnace and calcine at 350 °C for 17 min to dry the acidic solution and obtain magnetic graphene oxide powder;

[0076] (8) Dissolve the obtained magnetic graphene oxide powder in 50 ml of deionized water, and filter it through two layers of 0.3-micron microporous filter paper to obtain a filtrate. Subsequently, dialyze the filtrate with a dialysis bag having a molecular weight cut-off of 800 for 4 days to obtain a magnetic fluorescent graphene solution. The fluorescence spectrogram of the magnetic fluorescent graphene solution under 365 nm excitation light is shown in Figure 7 . The magnetic fluorescent graphene solution is freeze-dried to obtain magnetic fluorescent graphene.

Claims

1. A preparation method of magnetic fluorescent graphene, characterized in that Put the flake graphite and stainless steel needles into the grinding reaction tank of the grinding reaction device for magnetic grinding to obtain magnetic graphene; perform an oxidation reaction on the magnetic graphene, concentrated nitric acid and concentrated sulfuric acid to obtain a mixed solution; subject the mixed solution to ultrasonic treatment and calcination to obtain magnetic graphene oxide; dissolve the magnetic graphene oxide in deionized water, perform suction filtration and dialysis to obtain a magnetic fluorescent graphene solution; freeze-dry the magnetic fluorescent graphene solution to obtain magnetic fluorescent graphene; The described grinding reaction device includes a grinding reaction tank and a base. A concave space is provided at the top of the base, and a magnetic field generating electromechanical device is installed in the concave space; the magnetic field generating electromechanical device includes silicon steel sheets and coil windings wound around the silicon steel sheets, and the silicon steel sheets are vertically and evenly arranged in the concave space; a steel plate sheath is installed at the central position of the magnetic field generating electromechanical device, the grinding reaction tank is placed inside the steel plate sheath, and the bottom of the grinding reaction tank is connected to the bottom of the concave space; a window is provided in the middle of the base, and a fan is installed at the bottom of the window; a sealing cover and a heat exchange device are provided on the grinding reaction tank, the top of the sealing cover is connected to a thermocouple sensing device and an atmosphere control device, a pressure gauge is installed on the atmosphere control device, and the atmosphere control device is a gas pipe orifice and a gas valve; the bottom of the grinding reaction tank is connected to the base, and the periphery of the grinding reaction tank is surrounded by an electromagnet, which consists of an electromagnetic coil and an iron core; The ratio of the described magnetic graphene to concentrated nitric acid is 1:15 - 80, where the magnetic graphene is in grams and the concentrated nitric acid is in milliliters; the volume ratio of concentrated nitric acid to concentrated sulfuric acid is 3 - 4:

1.

2. The preparation method of the magnetic fluorescent graphene according to claim 1, wherein The mass ratio of the described flake graphite to stainless steel needles is 1:10 - 60.

3. The preparation method of the magnetic fluorescent graphene according to claim 1, characterized in that The mesh number of the described flake graphite is 30 - 400 mesh, and the size of the stainless steel needles is Φ: 0.3 - 3.0 mm, L: 2 - 30 mm.

4. The preparation method of the magnetic fluorescent graphene according to claim 1, wherein The time of the described magnetic grinding is 8 - 50 h.

5. The preparation method of the magnetic fluorescent graphene according to claim 1, wherein The time of the described oxidation reaction is 6 - 30 h.

6. The preparation method of the magnetic fluorescent graphene according to claim 1, wherein The time of the described ultrasonic treatment is 0.5 - 15 h, and the ultrasonic frequency is 40 - 60 KHz.

7. The preparation method of the magnetic fluorescent graphene according to claim 1, wherein The calcination temperature is 300 - 350 °C, and the calcination time is 15 - 20 min.

8. The preparation method of the magnetic fluorescent graphene according to claim 1, characterized in that The ratio of the described magnetic graphene oxide to deionized water is 1:20 - 50, where the magnetic graphene oxide is in grams and the deionized water is in milliliters; suction filtration is performed through two layers of filter paper, and the dialysis time is 3 - 5 d.

9. The preparation method of the magnetic fluorescent graphene according to any one of claims 1-8, characterized in that It includes the following steps: (1) Put the flake graphite and stainless steel needles into the grinding reaction tank of the grinding reaction device for magnetic grinding; (2) After grinding, cool to room temperature to obtain a mixture of magnetic nanographite flakes and stainless steel needles. Add the mixture of magnetic nanographite flakes and stainless steel needles to deionized water to separate the stainless steel needles, and obtain an aqueous solution of magnetic nanographite flakes; (3) Stir the aqueous solution of magnetic nanographite flakes and perform magnetic separation with a magnet to obtain magnetic nanographite flakes; (4) Put the magnetic nanographite flakes into an oven to dry and then grind them into powder to obtain magnetic graphene; (5) Perform an oxidation reaction on the magnetic graphene, concentrated nitric acid and concentrated sulfuric acid to obtain a mixed solution; (6) Put the mixed solution into an ultrasonic cleaner for ultrasonic treatment; (7) Put the ultrasonically treated mixed solution into a tube furnace for calcination to obtain magnetic graphene oxide; (8) Dissolve the magnetic graphene oxide in deionized water, filter it through two layers of filter paper to obtain a filtrate, and then dialyze the filtrate with a dialysis bag to obtain a magnetic fluorescent graphene solution; the magnetic fluorescent graphene solution is freeze-dried to obtain magnetic fluorescent graphene.

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