CN114455575A - Graphene and preparation method and application thereof - Google Patents

Abstract

The invention discloses graphene and a preparation method and application thereof. Adding a nano micromolecule aqueous solution into graphite under ultrasonic high-frequency oscillation to enable the nano micromolecule aqueous solution to be intercalated between expanded graphite layers, and then centrifuging to obtain a precipitate; and feeding the precipitate into a high-temperature kettle at 400-600 ℃, rapidly gasifying the intercalated solution, rapidly expanding the volume, directly delaminating the expanded graphite, and collecting the product at an outlet, namely the graphene. The prepared graphene product can be used for preparing washing and caring products, and grease on skin, hair follicle vicinity of hair roots and hair can be thoroughly removed by utilizing the physical action of the graphene nano-sheets. Not only has the effect of deeply cleaning the skin, but also can guide the skin regeneration.

Description

Graphene and preparation method and application thereof

Technical Field

The invention relates to the field of preparation processes, and particularly relates to graphene and a preparation method and application thereof.

Background

The synthesis method of graphene mainly includes two methods: mechanical methods and chemical methods. Mechanical methods include micro mechanical separation, epitaxy, and SiC heating; the chemical method is chemical reduction method and chemical dissociation method.

Most commonly, micromechanical separation methods, directly cut graphene sheets from larger crystals. Novoselovt et al prepared single layer graphene in 2004 using this method and could exist stably in the external environment. Typically, the bulk graphite surface is subjected to attrition, either by swelling with another material or by introducing defects into the pyrolytic graphite, to produce flakes of crystals containing a monolayer of graphene. However, the method has the disadvantage that the method screens out single-layer graphene flakes by using flakes obtained by rubbing the surface of graphite, the size of the graphene flakes is not easy to control, and a graphite flake sample with a sufficient length for application cannot be reliably manufactured.

The preparation of the stably existing graphene on a large scale is a precondition for the industrialization of the graphene. At present, the preparation methods of graphene mainly include a mechanical stripping method, an epitaxial growth method, a graphite oxide reduction method, a chemical vapor deposition method and the like. The graphite oxide reduction method is widely used by researchers because of its relatively simple preparation process. However, the graphene synthesized by the method has more defects and oxidation groups, and the application of the graphene in electronic devices is limited. The mechanical stripping method can optimally preserve the properties of the graphene, is simple in preparation method, environment-friendly and pollution-free in preparation process, is a widely used graphene preparation method in the scientific research field, and is more and more favored in actual production. For example, hme of manchester university separates graphene from a carbon material using an adhesive tape. Although this method of exfoliation of graphene is simple, only a limited amount of graphene can be produced. The microwave bursting method is to burst the intercalated graphite flakes at local high temperature by microwave, and can also continuously produce the graphene nanoplatelets in mass production, but due to local high temperature and nonuniform intercalation, the lattice fracture and the number of graphene layers of the produced graphene nanoplatelets are difficult to control, and the quality is mixed. The university of america also has the advantage of using small organic molecules as a detonator for graphene intercalation, but again with lattice damage and non-uniform quality.

201410846369.4 discloses spray drying and microwave production of graphene, which comprises hydrolyzing graphite under the action of strong acid such as H2SO4 and HNO3 and strong oxidant, or electrochemical peroxidation to form 0.1-50% graphite oxide aqueous solution; graphite oxide aqueous solution raw materials are put into a drying chamber through an atomizer by a peristaltic pump, materials in an atomized state are dissociated through microwaves, the materials are reduced into flocculent graphene which is easy to fly, the reduced graphene enters a cyclone collecting device along with flowing air to be collected, and the materials are loaded into a packaging bag through an air-closing discharger. However, the method still uses a strong oxidant to treat graphite, so that the surface electronic topological structure of graphene is damaged, groups such as hydroxyl or carboxyl are grafted, the resistance of graphene is increased, and the use of the strong oxidant can cause environmental pollution and bring potential safety hazards to preparation workers.

Disclosure of Invention

The invention aims to provide a method for preparing graphene with the number of layers effectively controlled to be about 1-5 layers, 3-6 layers, 4-9 layers and the like, or finer grades.

In order to achieve the purpose, the invention provides a preparation method of graphene, which is characterized in that a nano small molecule aqueous solution is added into graphite under ultrasonic high-frequency oscillation, so that the nano small molecule aqueous solution is intercalated between expanded graphite layers, and then the graphite layers are centrifuged to obtain a precipitate; and feeding the precipitate into a high-temperature kettle at 400-600 ℃, rapidly gasifying the intercalated solution, rapidly expanding the volume, directly delaminating the expanded graphite, and collecting the product at an outlet, namely the graphene.

Furthermore, the energy of the ultrasonic high-frequency oscillation is 28-80 KMz, 1000-3000W.

Further, the length of the graphite is 5-10 microns, and the carbon content is more than 95%.

Furthermore, the small molecule water of the nanometer small molecule water solution is less than 10 water molecules.

Further, the nano micromolecule water solution is obtained by passing purified water through a stainless steel pipe with high magnetic force lines, pulling water molecules through the high magnetic force lines, and pulling water molecule groups from macromolecule groups into micromolecule groups.

Further, the weight ratio of the nano micromolecule water solution to the graphite is 1: 10-20.

Further, the centrifugation condition is 2000-5000 rpm for 3-10 minutes.

Further, the pressure of the high-temperature kettle is 1-2 atm, the temperature is 400-600 ℃, and the gas flow rate is 100-300 ml/min.

The invention also protects the graphene prepared by the preparation method.

The invention also protects the application of the graphene in washing and caring articles.

Furthermore, the washing and caring product is used for washing and caring skin and hair.

Further, the washing and caring product is soap, perfumed soap, washing powder, laundry detergent, shampoo, facial cleanser, skin moistening cream, and hair conditioner.

According to the method, firstly, a chemical intercalation is utilized, a nano micromolecule water solution is intercalated between layers of expanded graphite by high-frequency oscillation energy of 28-80 KMz of ultrasonic waves and 1000-3000W, centrifugal separation is carried out for 3-10 minutes at 2000-5000 rpm, then the nano micromolecule water solution is fed into a high-temperature kettle at 400-600 ℃, the solution of the intercalation is rapidly gasified and rapidly expanded in volume, the expanded graphite is directly delaminated, and finally, graphene nanoplatelets with different surface areas are separated by gas power through multiple tests to continuously produce high-quality graphene nanoplatelets (20-40 kg/hour of continuous mass-production few-layer graphene nanoplatelets). In the production process, a large amount of sulfuric acid and strong oxidant is not needed, and a large amount of pure water is not needed for cleaning the sulfuric acid, so that the burden of environmental pollution is avoided. And the graphene nanoplatelets have complete crystal lattices, and the existence of no residual acid is more favorable for the application condition of the rear end.

The nano micromolecule water solution is a micromolecule water cluster, generally 50-70 water molecules are used as a cluster, and the micromolecule water is less than 10 water molecules. Purified water passes through a stainless steel pipe with high magnetic force lines (about 10000 gausses), and water molecules are dragged by the high magnetic force lines to form small molecular groups from large molecular groups.

The graphene prepared by the preparation method of the invention comprises the following steps:

1. the few-layer stripping of the graphene is completed, and the number of layers can be effectively controlled to be about 1-5 layers, 3-6 layers, 4-9 layers and the like, or finer grades. The products produced by the equipment are 1-9 layers of products, the average weight of the products is lighter as the number of layers is lower, and the products with different layers are obtained in the cyclone separator through precise airflow control. Such as 4-9 layers, 3-6 layers, 1-5 layers and 1-3 layers of the lightest product.

2. The production equipment can be used for continuous mass production, and can realize continuous feeding and continuous discharging.

3. The produced graphene microchip has no excessive mechanical or chemical interference in the process, and the microchip has complete crystal lattices and good electric conductivity and heat conductivity.

4. The production equipment has extremely low energy consumption and extremely low pollution in the production process.

The prepared graphene product can be used for preparing washing products for skin and hair, and is not limited to soap, perfumed soap, washing powder, laundry detergent, shampoo, facial cleanser, skin lotion and hair conditioner. The physical action of the graphene nano-sheets is utilized to thoroughly remove grease on the skin, the vicinity of hair follicles of hair roots and hair. Not only has the effect of deeply cleaning the skin, but also can guide the skin regeneration.

Drawings

FIG. 1 is a schematic structural diagram of the present invention, wherein A, B, C, D, E are 5 product collecting ports.

Fig. 2 is an international graphene layer number comparison standard graph.

Fig. 3 is a typical single layer graphene Raman spectrum.

FIG. 4 is a scanning electron microscope image of a low magnification few layer graphene film.

FIG. 5 is a transmission electron microscope image of a low magnification few layer graphene film.

FIG. 6 is a transmission electron microscope image of a high magnification few layer graphene film.

Fig. 7 is a single layer graphene Raman spectrum with a laser wavelength of 514.5 nm.

Fig. 8 is a single layer graphene Raman spectrum transferred onto silicon wafer with a laser wavelength of 488 nm.

Fig. 9 is a photograph of the appearance of the soap prepared in example 2.

Fig. 10 is a graph comparing the state of hair after shampooing using the shampoo prepared in example 4.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention. The examples do not specify particular techniques or conditions, and are performed according to the techniques or conditions described in the literature in the art or according to the product specifications. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products commercially available.

The extracts used in the following examples were obtained by extraction according to a conventional method.

Example 1: preparation of graphene

Screening raw materials: selecting 5-10 micrometer graphite with carbon content greater than 95%.

Pretreatment of raw materials: adding a nano micromolecule aqueous solution into the screened raw materials under the condition of 1000-3000W and the ultrasonic high-frequency oscillation energy of 28-80 KMz to enable the weight ratio of the nano micromolecule aqueous solution to the graphite to be 1: 10-20, and then carrying out centrifugal separation at 2000-5000 rpm for 3-10 minutes. For example, the preparation method comprises the following steps of passing purified water through a stainless steel pipe to obtain the aqueous solution of the nano micromolecules, wherein the diameter of the stainless steel pipe is 10mm in inner diameter, the outer diameter of the stainless steel pipe is 16mm, the length of the stainless steel pipe is 40 cm, 10000 gausses are externally arranged for 3-4 groups, the water pressure is 2-3 kilograms, and the flow rate is 2-3 tons/hour.

Preparation: feeding the centrifuged precipitate from a feed inlet; refer to the production equipment diagram of fig. 1. Adjusting the separating plate, adjusting the pressure of the reaction kettle to be 1-2 atm, the temperature to be 400-600 ℃, and the gas flow rate to be 100-300 ml/min. Wherein the feed inlet is quantitatively fed into the high-temperature kettle by a screw conveying device, the heat balance in the kettle is maintained, and the constant temperature is maintained so as to be beneficial to maintaining continuous production. The bottom is a controllable clean air or inert gas inlet, and the air quantity is maintained to be less than 2000 under the condition that the number of Reynolds is less than that of laminar flow, so that the graphene nanoplatelets are sequentially separated. Adjusting the parameter of Reynolds number to be 1; 2. feeding humidity; 3. the air speed of the blower; 4. the height of the baffle; 5. the temperature of the reaction kettle; 6. ultra-pure water, etc., which are automatically controlled by a computer, and the parameters of which can be changed by the computer. A, B, C, D and E are 5 product collecting ports.

The dimensionless number Re of the ratio of the inertia force to the viscous force in the fluid motion is UL/v. Wherein U is a speed characteristic scale, L is a length characteristic scale, and ν is a kinematic viscosity coefficient.

Reynolds number (Reynolds number), a dimensionless number that can be used to characterize fluid flow, is denoted by Re, where Re is ρ vd/η, where v, ρ, η are the flow rate, density and viscosity coefficient of the fluid, respectively, and d is a characteristic length. E.g., fluid flows through a circular pipe, then d is the pipe diameter. The reynolds number can be used to distinguish whether the flow of the fluid is laminar or turbulent and can also be used to determine the resistance to flow of the object in the fluid. For example, for the flow of a pellet in a fluid, when Re is much smaller than "1", its resistance f is 6 pi r η v (called stokes formula), and when Re is much larger than "1", f' is 0.2 pi r2v2 regardless of η. Generally, the Reynolds number Re <2300 of the pipeline is in a laminar state, Re ═ 2300-4000 is in a transition state, Re >4000 is in a turbulent state, and Re >10000 is in a complete turbulent state. Under different flowing states, the motion law, the distribution of flow velocity and the like of the fluid are different, so that the ratio of the average flow velocity V to the maximum flow velocity Vmax of the fluid in the pipeline is also different. The magnitude of the reynolds number thus determines the flow characteristics of the viscous fluid.

Product collection and detection: the graphene is obtained by collecting the products from the 5 product collecting ports A, B, C, D and E. The characterization data of the prepared graphene powder are as follows:

raman spectroscopy: measuring by laser with wavelength of 633nm, power less than 10 microwatts and 100 times of objective lens; sample no treatment, typical characteristics: raman 2D peak width: 30-45/cm, and the Raman peak intensity ratio is I_2D/I_G:0.7-1.0。

Electron microscope SEM: 5.0kv second electronic image; sample treatment: the dispersion was gently shaken by hand in isopropanol (non-sonicated) and a drop of clear solution was blown dry onto a glass slide with nitrogen. Typical characteristics: monodisperse few-layer graphene sheets.

TEM as 80 KV; sample treatment: dispersed in isopropanol (non-sonicated) with gentle shaking, a drop of clear aqueous solution on a clean copper grid.

The quality and layer thickness of graphene were judged by raman: the Raman spectrum provides a characterization means which has high efficiency and no damage and can directly observe the interaction of the electron and the electron, and the method is widely applied to the research of graphene. Through the peak position, the peak width and the peak shape change of the Raman spectrum of the graphene, the doping degree, the defect level, the number of layers, the interlayer stacking mode and the like of the graphene can be effectively represented.

The graphene obtained by the preparation is shown in figures 3-8 and table 1. Wherein figure 2 is an international graphene layer number versus standard graph. Fig. 3 is a typical single layer graphene Raman spectrum. Mainly comprises 1350cm-1 (peak D), 1583cm-1 (peak G), 1620cm-1 (peak D'), 2680cm-1 (peak 2D), 2950cm-1 (peak D + peak G), 3245cm-1 (peak 2D) and 4290cm-1 (peak 2D + peak G). Of these, D, G, 2D peaks are the three most important graphene characteristic peaks. The D peak, also commonly referred to as a defect peak, can be used to assess defect levels and impurity content in graphene. Generally, single crystal graphene such as graphene obtained from HOPG by using a micromechanical lift-off method can only detect a very weak defect peak at the edge. From the area ratio of the peak values, the number of layers of the graphene prepared in the embodiment can be determined to be about 2-5 by comparison.

FIG. 4 is a scanning electron microscope image of a low magnification few layer graphene film. FIG. 5 is a transmission electron microscope image of a low magnification few layer graphene film. FIG. 6 is a transmission electron microscope image of a high magnification few layer graphene film. Fig. 7 is a single layer graphene Raman spectrum with a laser wavelength of 514.5 nm. It can be seen that: the flake graphene has a complete structure, high purity and no other impurities. FIG. 8 is a single layer graphene Raman spectrum transferred onto a silicon wafer with a laser wavelength of 488 nm.

TABLE 11 Table of D/G Peak intensity and Peak area ratio

Example 2 preparation of graphene soap

Raw materials: 0.1 to 0.3 g of 1 to 5-layer graphene obtained in example 1, 150g of white oil, 150g of olive oil, 100g of coconut oil, 100g of palm oil, 73g of sodium hydroxide, and 175g of water.

The preparation method comprises the following steps: mixing the above materials.

The soap prepared is shown in fig. 9. After full saponification reaction, the finished soap is hard and thick, fine and smooth in texture, rich and stable in foam, and is not easy to soften or collapse in use. Saponification time: 20-30 minutes. And (3) mature period: 3-4 weeks. Is suitable for skin: especially greasy skin, and has good effects of deep cleaning and sterilization.

Effect verification: 1 g of graphene soap is fully dissolved in 50g of bacteria water, and after 1 hour, the microorganisms are detected by a Lubang ATP fluorescent microorganism detector, so that the number of the microorganisms is 1.2-2.0% of the stock solution.

Example 3 preparation of graphene facial cleanser

Raw materials: 1 small soup spoon of salt, 3 teaspoons of honey and two egg whites, and 1-5 layers of graphene obtained in example 1 is 1-2 per mill (the total weight is occupied).

The manufacturing steps of the facial cleanser are as follows:

1. stirring egg white and honey in a container along one direction until fine foam is obtained.

2. Adding salt into a small bowl, adding the mixed solution of Mel and ovum gallus Domesticus album, and stirring clockwise until completely mixed.

3. Adding graphene accounting for 1-2 per mill of the total weight, continuously stirring for 2 hours at 60-70 ℃, and standing for 8 hours.

The experimenter feels pain on day 1 after washing with the facial cleanser of the present invention (the nanocarbon cuts the aged cutin of the epidermis layer, if the skin has a wound or inflammation, the skin has nerve endings, the skin is thin and tender, such as under the eyes, and the use is not affected), and feels slippery (the skin touches the chin, and is particularly smooth) on day 2; the 3 rd day is oil (removing the scale, opening the blocked hair follicle thoroughly, overflowing the oil, and cleaning for the 2 nd time at this moment to wash off the oil); it is cool on day 4 (touch chin, smooth and clean, touch forehead, soft and tender, and good mood at all times). The facial cleanser has deep skin cleaning effect, can guide skin regeneration, and is fresh and comfortable after being cleaned by the graphene facial cleanser.

Example 4 preparation of graphene shampoo

The principle is as follows: the physical action of the graphene nano-sheets is utilized. The grease near the hair follicle of the human hair root and on the hair is thoroughly removed.

Raw materials (weight ratio): 0.1-1% of coconut oil, 0.1-1% of salt, 0.1-1% of ethylene glycol, 1-3% of carbomer, 0.1-1% of titanium dioxide, 0.1-1% of citric acid, 0.1-1% of rosemary extract, 0.1-1% of orchid extract, 0.1-1% of Chinese yam polysaccharide extract, 0.1-1% of EDTA disodium, 0.2-2% of diethanolamine (an alkaline neutralizing agent for adjusting the pH value of carbomer to be 6.5-7.5), 0.1-0.3% of graphene and the balance of water. Each extract is extracted by a conventional extraction method.

The preparation method of the shampoo comprises the following steps: and adding carbomer into water, standing for 8-24 hours for curing, adding the above components into the cured carbomer, fully stirring and uniformly mixing, adding diethanolamine to adjust the pH to 6.5-7.5, packaging and boxing.

Experimenters use the graphene shampoo provided by the invention to have good feeling after shampooing, smooth and soft hair, especially for cleaning after dyeing and cleaning heavy oil hair. The hair loss can be obviously reduced after the hair-care product is continuously used for 3-5 times. After the hair-care agent is used for one week, 20-30 hair-dropping roots per day are reduced to below 5-6 hair-dropping roots per day. See fig. 10, where a is the hair state before use and B is the hair effect after one week of use. It is obvious that the hair is smooth and glossy after being used for one week, and the oil removing effect is obvious. Because human hair follicles discharge oil, excess oil can break the roots of the hair causing hair loss. Hair loss is caused by the clogging of hair follicles by grease, and the more clogged, the more severe the hair loss. The hair follicle can be fully cleaned by using the graphene shampoo, and hair loss is reduced. Not only has excellent oil removing property, but also has good effect on deep cleaning of head skin, and can induce skin regeneration, and feel refreshing and comfortable after washing with graphene skin-moistening whey.

Example 5 preparation of graphene skin lotion

Raw materials: 0.1-1% of cocamide MEA, 0.1-1% of ethylene glycol distearate, 0.1-1% of salt, 0.1-1% of EDTA disodium, 0.1-1% of citric acid, 0.1-1% of magnesium chloride, 0.1-1% of orchid extract, 0.1-1% of aloe polysaccharide extract, 1-3% of carbomer, 0.1-0.3% of graphene, 0.2-2% of diethanolamine (an alkaline neutralizer for adjusting the pH of carbomer to 6.5-7.5), and the balance of water.

The preparation method of the skin-moistening milk comprises the following steps: and adding carbomer into water, standing for 8-24 hours for curing, adding the above components into the cured carbomer, fully stirring and uniformly mixing, adding diethanolamine to adjust the pH to 6.5-7.5, packaging and boxing.

After the skin moistening cream disclosed by the invention is used by an experimenter, the skin does not dry, the moisturizing effect is obvious, and the skin is fine and smooth.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made in the above embodiments by those of ordinary skill in the art without departing from the principle and spirit of the present invention.

Claims (12)

1. A preparation method of graphene is characterized in that a nano small molecule aqueous solution is added into graphite under ultrasonic high-frequency oscillation, so that the nano small molecule aqueous solution is intercalated between expanded graphite layers, and then centrifugation is carried out to obtain a precipitate; and feeding the precipitate into a high-temperature kettle at 400-600 ℃, rapidly gasifying the intercalated solution, rapidly expanding the volume, directly delaminating the expanded graphite, and collecting the product at an outlet, namely the graphene.

2. The method for preparing graphene according to claim 1, wherein the energy of the ultrasonic high-frequency oscillation is 28 to 80KMz, 1000 to 3000W.

3. The method of preparing graphene according to claim 1, wherein the graphite has a length of 5 to 10 μm and a carbon content of more than 95%.

4. The method for preparing graphene according to claim 1, wherein the small molecule water in the nano small molecule water solution is 10 or less water molecules.

5. The method for preparing graphene according to claim 1, wherein the nano small molecule aqueous solution is obtained by passing purified water through a stainless steel tube with high magnetic force lines, pulling water molecules through the high magnetic force lines, and pulling water molecule groups from large molecule groups into small molecule groups.

6. The preparation method of graphene according to claim 1, wherein the weight ratio of the nano small molecule aqueous solution to graphite is 1: 10-20.

7. The method for preparing graphene according to claim 1, wherein the centrifugation is performed at 2000-5000 rpm for 3-10 minutes.

8. The method for preparing graphene according to claim 1, wherein the pressure of the high-temperature kettle is 1 to 2atm, the temperature is 400 to 600 ℃, and the gas flow rate is 100 to 300 ml/min.

9. Graphene produced by the production method according to any one of claims 1 to 8.

10. Use of the graphene according to claim 9 for washing products.

11. Use according to claim 10, wherein the cleaning article is a cleaning article for skin or hair.

12. The use according to claim 11, wherein the toiletry product is a soap, washing powder, laundry detergent, shampoo, face wash, body lotion, hair conditioner.

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