CN104891485A - Method for preparing nano graphite sheet - Google Patents

Abstract

The invention relates to a method for preparing a nano graphite sheet, which is prepared by taking expanded graphite powder as a raw material, adding the expanded graphite powder in a dispersive solution according to the ratio of 0.5-10g/L, circularly adding the mixed solution into an ultrasonic pulverizer through a centrifuge pump, starting the ultrasonic pulverizer for carrying out ultrasonic peeling nano-crystallization operation on the mixed solution for 40-72h to obtain a nano graphite sheet solution, wherein the dispersive solution is an ethanol solution, and the nano graphite sheet solution obtained through ultrasonic peeling nano-crystallization operation is subjected to standing, filtering and drying to obtain the nano graphite sheet powder with the thickness of 20-50nm. The method disclosed by the invention is simple in preparation process, free of complex equipment, capable of continuous operation, high in production efficiency, and applicable to industrialized continuous production in a large scale.

Description

A kind of preparation method of nanographite sheet

technical field

The invention relates to a preparation process of a graphite material, in particular to a preparation method of a nano-graphite sheet.

Background technique

Nano-graphite sheet is a two-dimensional nano-graphite material with a thickness of nanometer scale, which is stacked by single-layer carbon atom planar structure graphene. Since the graphite flakes are combined by weak van der Waals force, the flakes can be peeled off to obtain nano-graphite materials. Nano-graphite sheets not only have extremely high corrosion resistance and chemical stability, but also have good electrical and thermal conductivity.

There are many preparation methods for nano-graphite flakes, and the commonly used physical methods are mechanical ball milling and ultrasonic pulverization. The mechanical ball milling method is to use the principle that the interaction force between graphite layers is smaller than the binding force of carbon atoms in the graphite layer and is easy to be peeled off to prepare nano-graphite sheets. For example, CN104505512A discloses a method for preparing microcrystalline graphene by ball milling, which has a long preparation time (80-120 hours) and high loss of balls used in ball milling.

The ultrasonic pulverization method is to use the action of ultrasound to generate a strong pressure field, which causes the liquid to cavitate, break or burst, so that the layers of expanded graphite will fall off, thereby obtaining nano-graphite sheets. CN203794630U discloses a kind of industrial device for continuous production of graphene powder, which adopts the joint application of ultrasonic pulverizer and microwave oven to prepare graphene, and the required equipment requirements are relatively high, and microwave devices, spray drying devices, etc. need to be equipped.

Contents of the invention

The technical problem to be solved by the present invention is to overcome the deficiencies of the prior art, and provide a preparation method of nanographite sheets with simple and reasonable process, easy operation, high preparation efficiency, and suitable for industrialized and continuous mass production.

The technical solution adopted by the present invention to solve the above-mentioned technical problems is: a preparation method of nano-graphite sheets, which uses expanded graphite powder as a raw material, and is characterized in that: firstly, the expanded graphite powder is added to a dispersion solvent to form a mixed solution; Then, the mixed liquid is circulated and added to the ultrasonic pulverizer through a centrifugal pump; the ultrasonic pulverizer is started to carry out ultrasonic stripping and pulverization of the mixed liquid for 40 minutes to 72 hours to obtain a nanographite flake solution.

The dispersing solvent is an alcohol solution, and the concentration range of the expanded graphite powder in the dispersing solvent is 0.5 to 10 g/L. Ultrasonic stripping and crushing operations obtain the nano-graphite flake alcohol solution. After the nano-graphite flake alcohol solution is left to stand, filter and drying to obtain graphite nanosheet powder with a thickness of 20-50 nanometers.

The alcohol solution is an ethanol solution with a mass ratio of water to ethanol lower than 1:2.

The dispersion solvent is an aqueous solution containing a surfactant, and the concentration of the expanded graphite powder in the dispersion solvent is 0.5-1.5 g/L.

The aqueous solution contains 0.1-2% sodium carboxymethylcellulose (CMC) surfactant, and the pH value of the solution is 11.

The aqueous solution contains a sodium dodecylbenzenesulfonate dispersant with a mass content of 0.5%.

The ultrasonic power of the ultrasonic generator in the ultrasonic pulverizer is adjustable at 1.2-2.2 kilowatts, and the ultrasonic frequency is 20KHz.

The preparation process of the present invention is simple, and ultrasonic nanometerization utilizes the strong pressure field generated under the action of ultrasonic to cause cavitation, fragmentation or bursting of the liquid, thereby causing exfoliation between layers of expanded graphite to obtain nanographite sheets. Only simple, common, and easy-to-operate equipment such as an ultrasonic generator is required. The cavity of the ultrasonic pulverizer is continuously fed by a centrifugal pump, and cooling circulating water is installed outside the cavity. The obtained nano-graphite flake solution can be used in production or scientific experiments, or obtain nano-graphite flake powder by methods such as filtration, centrifugation, and drying. The present invention only needs to be equipped with simple matching devices such as a centrifugal pump, and the drying process can be completed by using simple common devices or by natural drying.

specific implementation plan

The present invention will be further described below in conjunction with specific embodiments.

A preparation method of nano-graphite flakes, adding 0.5-10 g/L of expanded graphite obtained from 80-mesh flake graphite into ethanol or an aqueous solution containing a surfactant, and sending the solution into the cavity of an ultrasonic cell pulverizer by a centrifugal pump In the body, after 40 minutes to 72 hours of continuous action, the dispersion solution of graphite nano flakes can be obtained.

The medium used in the process of nanometerization of expanded graphite in the present invention is ethanol solution. The present invention can also use other solvents, such as adding an appropriate amount of surfactants in aqueous solution, such as sodium carboxymethyl cellulose, sodium dodecylbenzenesulfonate, etc., as dispersants to weaken the agglomeration of expanded graphite and make expanded graphite It is evenly distributed in the solution, and the degree of nanometerization is higher. The ultrasonic power is controlled above 2 kilowatts, the concentration of powder and alcohol solution is about 10g/L, and the ultrasonic time is 40 minutes to obtain graphite nanosheets with good uniformity, with a diameter of 5-50 microns and a thickness of 20-50 nanometers.

The solution can be a mixed solution of water and surfactant, but the difference from the alcohol solution is that the concentration of the expanded graphite raw material in the water solvent is a dilute solution with a concentration of 0.5-1.5g/L, and what is obtained is a dispersion of graphite nanosheets , Standing for 2 months without precipitation.

The ultrasonic power of the ultrasonic generator in the ultrasonic pulverizer is adjustable at 1.2-2.2 kilowatts, and the ultrasonic frequency is 20KHz.

Embodiment 1: a kind of preparation method of graphite nanosheet, it is carried out as follows: first take by weighing 200 order expanded graphite 3g, add the dehydrated alcohol of 6L, in the working cavity of ultrasonic pulverizer, continuous ultrasonic nanometerization, carry out After 72 hours, the solution was dried, and the obtained powder was graphite nano flakes with a diameter of 5-10 microns and a thickness of 30 nanometers.

Example 2: 80g of 80-mesh expanded graphite was added to 8L of 90% industrial alcohol by mass fraction, and the mixed liquid was continuously sent into the working container of the ultrasonic pulverizer by using a centrifugal pump, and continuously nano-sized by the supersonic pulverizer, and after 40 minutes, released Liquid, let it stand for 2 hours, pour out the supernatant, filter it with suction, and dry it. The obtained powder is nano-graphite flakes with a diameter of 20-50 microns and a thickness of 30 nanometers.

Example 3: Weigh 12g of expanded graphite, add 8L of deionized water and 0.1% sodium carboxymethylcellulose (CMC) mixture, adjust the pH value of the solution to 11 with ammonia water, continuously feed the material with a centrifugal pump, and crush the cells by ultrasonic The instrument nanometerizes the mixed liquid. After 24 hours, the resulting solution is an aqueous solution of nano-graphite flakes, and no precipitation occurs after standing for 2 months.

Example 4: Weigh 8g of expanded graphite, add 8L of deionized water and 0.5% mass fraction of sodium dodecylbenzenesulfonate mixed solution, adjust the pH value of the solution to 11 with ammonia water, continuously feed the material with a centrifugal pump, and use an ultrasonic cell pulverizer The mixed liquid is nano-sized, and after 72 hours, the obtained solution is an aqueous solution of nano-graphite flakes, and no precipitation occurs after standing for 2 months.

Claims (7)

1. A method for preparing nano-graphite sheets, which uses expanded graphite powder as a raw material, characterized in that: first, the expanded graphite powder is added to the dispersion solvent; then the mixed solution is circulated into the ultrasonic pulverizer by a centrifugal pump ; Start the ultrasonic pulverizer to perform ultrasonic stripping and nano-processing on the mixed solution for 40 minutes to 72 hours to obtain a nano-graphite sheet solution. 2. The preparation method of nano-graphite sheets according to claim 1, characterized in that: the dispersion solvent is an ethanol solution, and the concentration of expanded graphite powder in the dispersion solvent is 0.5 ~ 10g/L, and the ultrasonic nanometerization operation obtains ethanol solution of graphite nano flakes, after standing still, the ethanol solution of graphite nano flakes is filtered and dried to obtain graphite nano flake powders with a thickness of 20-50 nanometers. 3. The method for preparing graphite nanosheets according to claim 2, wherein the alcoholic solution is an ethanol solution with a water to ethanol mass ratio of less than 1:2. 4. The preparation method of nano-graphite sheets according to claim 1, characterized in that: the dispersion solvent is an aqueous solution containing a surfactant, and the concentration of expanded graphite powder in the dispersion solvent is 0.5-1.5 g/L. 5. The method for preparing graphite nanosheets according to claim 4, wherein the aqueous solution contains 0.1-0.5% sodium carboxymethylcellulose surfactant, and the pH value of the solution is 11. 6. The method for preparing graphite nanosheets according to claim 4, wherein the aqueous solution contains 0.5% sodium dodecylbenzenesulfonate dispersant. 7. The preparation method of nano-graphite sheets according to claim 1, characterized in that: the ultrasonic power of the ultrasonic generator in the ultrasonic pulverizer is adjustable at 1.2-2.2 kilowatts, and the ultrasonic frequency is 20KHz.