CN103172056A - Efficient separation and purification method of graphene oxide - Google Patents

Abstract

The invention discloses a high-efficiency separation and purification method of graphene oxide, which comprises the following steps: filtering a suspension liquid which is prepared from common graphite powder by a wet chemical oxidation method and contains graphite oxide and graphene oxide to obtain a graphene oxide dispersion liquid and a graphite oxide sludge; dropping an alkaline solution into the graphene oxide dispersion liquid to enable the pH value of the dispersion liquid to be 1.8-2.2, enabling the graphene oxide to be aggregated and settled, filtering to obtain a graphene oxide aggregate, cleaning, and drying to obtain a graphene oxide solid. The method provided by the invention can be used for efficiently separating and purifying the graphene oxide by using the alkaline solution as the auxiliary agent through a simple process. The method has the advantages of simple process, low cost, environmental protection, easily controlled operation conditions, pure product, low product loss rate and the like.

Description

Efficient separation and purification method of graphene oxide

technical field

The invention belongs to the field of carbon materials, and in particular relates to a high-efficiency separation and purification method for graphene oxide.

Background technique

Graphene oxide is a new type of carbon material. It is another important new discovery in the field of carbon materials after diamond-type, graphite-type, fullerene-type and carbon tube-type carbon materials. The research on graphene oxide can be traced back to 1855, when it mainly focused on its structure and synthesis method. From the mid-nineteenth century to the mid-twentieth century, scholars at home and abroad mainly focused on the preparation process of graphene oxide. There are four common methods for preparing graphene oxide: Brodie method, Staudenmaier method, Hummers method and electrochemical method.

In the past 30 years, while people have continued to work on confirming the structure of graphene oxide, they have also set off an upsurge in the application research of graphene oxide, especially the application research of graphene oxide and its composite materials has received more and more attention. Various composite materials prepared with graphene oxide as the matrix have shown very superior properties, and have become one of the inorganic materials that researchers are mainly concerned about.

At present, in the research of preparing graphene oxide by wet chemical oxidation method, the graphene oxide product is usually separated by techniques such as dialysis, high-speed centrifugation or sedimentation. However, the dialysis technology has the disadvantage of a long separation period (several weeks). Compared with dialysis technology, high-speed centrifugation or sedimentation technology has a shorter separation period (within a few hours), but because the supernatant containing a large amount of graphene oxide is discarded during the separation process, the product loss is serious and separation The technical problem of low purification yield.

Contents of the invention

The invention aims at the technical problem in the prior art that it is difficult to separate and purify graphene oxide prepared by a wet chemical oxidation method using ordinary graphite powder as a raw material, and provides a method for efficiently separating and purifying graphene oxide.

The method for efficiently separating and purifying graphene oxide of the present invention comprises the steps:

① Filtrating the suspension containing graphite oxide and graphene oxide prepared by wet chemical oxidation method using ordinary graphite powder as raw material to obtain graphene oxide dispersion and graphite oxide mud;

② Add alkaline solution to the graphene oxide dispersion liquid dropwise, so that the pH value of the dispersion liquid is 1.8~2.2, preferably 2.0, so that the graphene oxide aggregates and settles, and then the graphene oxide aggregates are obtained by filtration, washed, Dry to obtain graphene oxide solid.

In the present invention, the ordinary graphite powder is flake graphite powder, expandable graphite powder or microcrystalline graphite powder; the wet chemical oxidation method is the Staudenmaier method, Brodie method or Hummers method.

In the present invention, in step ① and step ②, ordinary filter paper such as qualitative or quantitative filter paper for experiments is used for filtration, or a filter membrane such as a microporous filter membrane is used for filtration.

In the present invention, the alkaline solution can be any alkaline solution with a pH greater than 7, preferably 0.5-5 mol/L sodium hydroxide or potassium hydroxide solution.

In step ②, the drying temperature of the graphene oxide aggregates may be 40-90° C., and the drying time may be 6-12 hours.

Preferably, the graphite oxide sludge obtained in step ① is cleaned and dried to obtain a graphite oxide solid product. The drying temperature of graphite oxide sludge can be 40~90℃, and the drying time is 6~12 hours.

The positive progress effect of the present invention lies in: the present invention aims at the technical problem of difficult product separation in the process of preparing graphene oxide by wet chemical oxidation method, and efficiently separates and purifies the product while preparing graphene oxide. The method has the advantages of simple process, low cost, environmental protection, easy control of operating conditions, pure product, low product loss rate and the like.

Description of drawings

Fig. 1 is the photo of the graphene oxide dispersion (left) obtained during the separation and purification method of the present invention (left) and graphene oxide agglomeration (right) after adding alkaline solution; and

Fig. 2 is the XRD analysis spectrum of the graphene oxide obtained by the separation and purification method of the present invention.

Detailed ways

Example 1

Graphene oxide was prepared by the Hummers method with flake graphite powder as the main raw material. Take 100mL of graphite oxide and graphene oxide suspension obtained by reaction, first add 200mL of deionized water to dilute, and use medium-speed quantitative filter paper to filter and separate to obtain dark yellow graphite oxide mud and graphene oxide solution. The obtained dark yellow graphite oxide sludge was washed with deionized water until the filtrate was tested with BaCl ₂ to be free of SO ₄ ²⁻ , and dried in an oven at 90° C. for 6 hours to obtain solid graphite oxide. Take 10 mL of the graphene oxide solution obtained by filtration and add 30 mL of 1 mol/L sodium hydroxide solution. At this time, the solution is acidic (pH value is 2.2), and dark yellow suspended graphene oxide aggregates are obtained. It was filtered and separated by medium-speed quantitative filter paper to obtain graphene oxide aggregates, and the aggregates were washed with deionized water until the filtrate was tested by BaCl ₂ to be free of SO ₄ ^2- . The obtained agglomerate was dried in an oven at 90° C. for 6 hours to obtain a graphene oxide solid.

The results show that using this technology to separate and purify graphene oxide products can reduce the loss rate of graphene oxide products to 0%, and the product purity is as high as 99.9%.

As shown in the photo in Figure 1, the left side is the graphene oxide dispersion; the right side is the graphene oxide aggregate after adding alkaline solution. The XRD analysis result of graphene oxide solid is shown in Fig. 2, and described XRD analysis is X-ray diffraction analysis, adopts the D8Advance type diffractometer of German Bruker company. Figure 2 can prove that pure graphene oxide can be obtained by using the method of the present invention.

Example 2

Graphene oxide was prepared by the Staudenmaier method using expandable graphite powder as the main raw material. Take 100mL of graphite oxide and graphene oxide suspension obtained by reaction, first add 200mL of deionized water to dilute, and use medium-speed quantitative filter paper to filter and separate to obtain dark yellow graphite oxide mud and graphene oxide solution. The obtained dark yellow graphite oxide sludge was washed with deionized water until the filtrate was tested with BaCl ₂ to be free of SO ₄ ²⁻ , and dried in an oven at 40° C. for 12 hours to obtain solid graphite oxide. Take 10 mL of the graphene oxide solution obtained by filtration and add 30 mL of 1 mol/L potassium hydroxide solution. At this time, the solution is acidic (pH value is 2.0), and dark yellow suspended graphene oxide aggregates are obtained. It was filtered and separated by medium-speed quantitative filter paper to obtain graphene oxide aggregates, and the aggregates were washed with deionized water until the filtrate was tested by BaCl ₂ to be free of SO ₄ ^2- . Finally, the obtained aggregate was dried in an oven at 40° C. for 12 hours to obtain a graphene oxide solid.

The results show that using this technology to separate and purify graphene oxide products can reduce the loss rate of graphene oxide products to 0%, and the product purity is as high as 99.9%.

Example 3

Graphene oxide was prepared by Brodie method using microcrystalline graphite powder as the main raw material. Take 100mL of graphite oxide and graphene oxide suspension obtained by reaction, first add 200mL of deionized water to dilute, and use medium-speed quantitative filter paper to filter and separate to obtain dark yellow graphite oxide mud and graphene oxide solution. The obtained dark yellow graphite oxide sludge was washed with deionized water until the filtrate was tested with BaCl ₂ to be free of SO ₄ ²⁻ , and dried in an oven at 90° C. for 6 hours to obtain solid graphite oxide. Take 10 mL of the graphene oxide solution obtained by filtration and add 6 mL of 5 mol/L potassium hydroxide solution. At this time, the solution is acidic (pH value is 1.8), and dark yellow suspended graphene oxide aggregates are obtained. It was filtered and separated by medium-speed quantitative filter paper to obtain graphene oxide aggregates, and the aggregates were washed with deionized water until the filtrate was tested by BaCl ₂ to be free of SO ₄ ^2- . Afterwards, the obtained agglomerate was dried in an oven at 90° C. for 6 hours to obtain a graphene oxide solid.

The results show that using this technology to separate and purify graphene oxide products can reduce the loss rate of graphene oxide products to 0%, and the product purity is as high as 99.9%.

Example 4

Using microcrystalline graphite powder as the main raw material, graphene oxide was prepared by the Hummers method. Take 100mL of graphite oxide and graphene oxide suspension obtained by reaction, first add 200mL of deionized water to dilute, and use medium-speed quantitative filter paper to filter and separate to obtain dark yellow graphite oxide mud and graphene oxide solution. The obtained dark yellow graphite oxide sludge was washed with deionized water until the filtrate was tested with BaCl ₂ to be free of SO ₄ ²⁻ , and dried in an oven at 90° C. for 6 hours to obtain solid graphite oxide. Take 10 mL of the graphene oxide solution obtained by filtration and add 60 mL of 0.5 mol/L potassium hydroxide solution. At this time, the solution is acidic (pH value is 2.2), and dark yellow suspended graphene oxide aggregates are obtained. It was filtered and separated by medium-speed quantitative filter paper to obtain graphene oxide aggregates, and the aggregates were washed with deionized water until the filtrate was tested by BaCl ₂ to be free of SO ₄ ^2- . Afterwards, the obtained agglomerate was dried in an oven at 90° C. for 6 hours to obtain a graphene oxide solid.

The results show that using this technology to separate and purify graphene oxide products can reduce the loss rate of graphene oxide products to 0%, and the product purity is as high as 99.9%.

Example 5

Graphene oxide was prepared by Hummers method with expandable graphite powder as the main raw material. Take 100mL of graphite oxide and graphene oxide suspension obtained by reaction, first add 200mL of deionized water to dilute, and use medium-speed quantitative filter paper to filter and separate to obtain dark yellow graphite oxide mud and graphene oxide solution. The obtained dark yellow graphite oxide sludge was washed with deionized water until the filtrate was tested with BaCl ₂ to be free of SO ₄ ²⁻ , and dried in an oven at 40° C. for 12 hours to obtain solid graphite oxide. Take 10 mL of the graphene oxide solution obtained by filtration and add 60 mL of 0.5 mol/L sodium hydroxide solution. At this time, the solution is acidic (pH value is 2.2), and dark yellow suspended graphene oxide aggregates are obtained. It was filtered and separated by medium-speed quantitative filter paper to obtain graphene oxide aggregates, and the aggregates were washed with deionized water until the filtrate was tested by BaCl ₂ to be free of SO ₄ ^2- . Finally, the obtained aggregate was dried in an oven at 40° C. for 12 hours to obtain a graphene oxide solid.

The results show that using this technology to separate and purify graphene oxide products can reduce the loss rate of graphene oxide products to 0%, and the product purity is as high as 99.9%.

Claims (9)

1. the highly effective separation purification method of a graphene oxide, it comprises the steps:

1. the suspension that contains graphite oxide and graphene oxide that makes through the wet-chemical oxidation style take the common graphite powder as raw material is filtered, obtain graphene oxide dispersion liquid and graphite oxide mud shape thing;

2. drip basic solution to the graphene oxide dispersion liquid, make the pH value to 1.8 of dispersion liquid ~ 2.2, make graphene oxide reunion sedimentation, then obtain after filtration the graphene oxide coacervate, clean, oven dry obtains the graphene oxide solid.

2. the method for claim 1 is characterized in that: step drips basic solution to the graphene oxide dispersion liquid in 2., makes the pH value to 2.0 of dispersion liquid.

3. the method for claim 1, it is characterized in that: described common graphite powder is crystalline graphite powder, expansible black lead powder or microlite ink powder; Described wet-chemical oxidation style is Shi Taodeng mayer method, Brodie method or Ha Musifa.

4. the method for claim 1 is characterized in that: 1. step adopts common filter paper or filter membrane to filter with step in 2..

5. method as claimed in claim 4 is characterized in that: 1. the common filter paper described in 2. is qualitative or quantitative paper to step with step; Described filter membrane is millipore filtration.

6. the method for claim 1, it is characterized in that: described basic solution is sodium hydroxide or the potassium hydroxide solution of 0.5 ~ 5mol/L.

7. the method for claim 1 is characterized in that: step 2. in, the bake out temperature of graphene oxide coacervate is 40 ~ 90 ℃, drying time is 6 ~ 12 hours.

8. the method for claim 1 is characterized in that: the graphite oxide mud shape thing that 1. step is obtained cleans, dry and obtain oxidation graphite solid.

9. method as claimed in claim 8 is characterized in that: step 1. in, the bake out temperature of graphite oxide mud shape thing is 40 ~ 90 ℃, drying time is 6 ~ 12 hours.

Images