KR101337969B1

KR101337969B1 - mixture of multi-layered graphene for adsorbing organic material

Info

Publication number: KR101337969B1
Application number: KR1020110109772A
Authority: KR
Inventors: 이시춘; 신철민; 이태성
Original assignee: 주식회사 아이디티인터내셔널
Priority date: 2011-10-26
Filing date: 2011-10-26
Publication date: 2013-12-06
Also published as: KR20130045518A; WO2013062373A1

Abstract

The present invention relates to the use for adsorbing organic materials of a multilayer graphene mixture prepared by thermal shock of graphite oxide, and may selectively adsorb organic materials, particularly crude oil or waste oil, by the interlayer space separated in the form of accordion.

Description

Mixture of multi-layered graphene for adsorbing organic material}

The present invention relates to the use of organic material adsorption of a multilayer graphene mixture prepared by thermal shock of graphite oxide.

In 2004, a team of professors Professor Andre Geim of the University of Manchester succeeded in the first mechanical peeling of graphene from graphite using the "Scotch tape method" and also the quantum hole effect using the peeled graphene. Research has revealed the excellent electrical conductivity of graphene.

Such graphene has a structure in which carbon nanotubes are cut in the longitudinal direction and is similar to the graphene structure when the diameter of the walls of the carbon nanotubes is infinitely wide. The electrical conductivity, thermal and mechanical properties of graphene are comparable or superior to those of carbon nanotubes. Therefore, such graphene is being sought for application as a conductive material and strength reinforcing material. For example, there are active researches on replacing indium tin oxide (ITO), which is frequently used as a transparent electrode, and application to semiconductor materials. In addition, graphene is known to have the largest surface area among existing materials (Novoselov, K S, Geim, AK et al. Science 306, 666, 2004). It can be used as an electrode material for energy storage devices such as battery cells (Stoller, MD, Park, S., Zhu, Y., An, J., Ruoff, RS, Nano Lett. 8, 3498-3502).

Such graphene can be obtained by mechanical methods obtained by drawing from graphite, such as Andre Gaim's Scotch method, by chemical vapor deposition obtained by chemical vapor deposition on a substrate, by adding an oxidizing agent and / or a reducing agent to the graphite, and by thermal shock or by chemical reaction. And chemical exfoliation obtained by. Graphene produced by the chemical exfoliation method is different from the graphene by mechanical methods or chemical vapor deposition. In particular, graphene prepared by exfoliating graphite by thermal shock is also referred to as reduced graphene oxide. The graphite oxide exfoliation method by thermal shock has a problem that the quality of graphene is degraded due to the occurrence of defects of the graphene sheet itself due to oxidation in the manufacturing process, the residual of a large amount of oxygen groups, and the residual of the oxidizing agent or solvent used. Can have However, because graphene can be made into flakes in large quantities, it is suitable for production of supercapacitors or polymer composite products processed into flakes. In addition, the remaining oxygen group gives the advantage of improving the compatibility with the ceramic or polymer used as the base material.

The inventors of the present invention provide a method for producing graphene by thermal shock of graphite oxide in a chemical exfoliation method. In the patent application No. 2010-76871 and the divided application No. 2011-24855, the graphite oxide is dropped in a fluidized bed and separated and collected. An apparatus for producing the same has been disclosed. In addition, the present inventors have disclosed a device for producing a graphene structure material by inhaling graphite oxide in a backflow furnace in Patent Application No. 2011-53787.

The inventors of the present invention have found that the mixture of multilayered graphene prepared by giving thermal shock to the chemical exfoliation method, in particular, graphite oxide, has excellent selective adsorption capacity for organic matter in addition to the inherent thermal, electrical and mechanical properties of graphene, and completed the present invention. Was done.

Accordingly, an object of the present invention is to provide a multilayer graphene mixture for adsorption of organic materials having selective adsorption to organic materials.

The present invention provides a multilayer graphene mixture for adsorbent of organic materials obtained by thermal shock by passing graphite oxide through a fluidized bed maintained at 300 ° C to 1200 ° C. The multilayer graphene mixture may be determined to have a greater degree of peeling as the X-ray diffraction peak of graphite at 2θ = 26.5 ° and the X-ray diffraction peak of graphite oxide near 2θ = 12.7 ° are minimized. The average surface area of this mixture of multilayered graphenes is 200-2600 m ² / g.

The multilayer graphene mixture of the present invention is preferably prepared by stripping graphite oxide by the method described in co-pending patent application 2011-53787 by the inventors. The graphite oxide used has a carbon / oxygen ratio of 1 to 50/1 by an elemental analyzer and has a maximum peak near 2θ = 12 ° by X-ray diffraction analysis. The graphite oxide is formed by forming a functional group such as a hydroxyl group, a carboxylic acid group, an epoxy group in each layer by an oxidation reaction, and expands from about 3.4 kPa between layers of graphite powder as a raw material to about 7 kPa between layers. In the analysis, the peak of trace is shown around 2θ = 26 °, which is the characteristic of graphite powder, and the peak is around 2θ = 12.7 °. Such graphite oxide can be sufficiently peeled off quickly and evenly by the thermal shock by oxidizing agent is sufficiently inserted between the layers of graphite. When the carbon / oxygen ratio of the graphite oxide is smaller than 1/1, the graphene is finely divided, and when the carbon / oxygen ratio is larger than 50/1, graphene peeling occurs less. In order to increase the peeling efficiency, ultrasonic waves may be added in the peeling process by the oxidation process or the thermal shock. The graphite oxide is converted into a multilayer graphene mixture while being peeled off by thermal shock while raising the vertical fluidized bed. Heating of such a fluidized bed can be achieved by conventional methods by heaters or by microwaves. The temperature in the fluidized bed furnace is maintained at 300 ° C to 1200 ° C, preferably at 500 to 1200 ° C. The average number of layers of the multilayer graphene mixture is preferably 3 to 20.

As shown in the photograph of FIG. 1, the multilayer graphene mixture of the present invention can be inferred to exhibit high adsorption characteristics for organic materials by the space between the numerous graphene layers. The surface area of graphene used is 400 m ² / g and the carbon / oxygen ratio is about 25/1. The accordion type surface is well peeled off and the average number of layers is about 5 layers.

The multilayer graphene mixture may be used as an adsorbent in a fine nonwoven fabric, but carbonized after compression molding by mixing a binder, it is possible to obtain a pack-type adsorbent. Such pack adsorbents are particularly suitable for use as adsorbents of spilled crude or waste oils.

The multilayer graphene mixture by thermal shock according to the present invention shows high adsorption to organic materials unlike graphite oxide or graphite, and shows twice or more oil adsorption compared to graphene prepared by expanded graphite, carbon nanotubes or other methods. It shows the adsorption rate more than 50 times compared to the general oil adsorption cloth on the market, and it has excellent performance as an organic material adsorbent.

1 is an electron micrograph of the Enbarotech graphene ER-2510 of the present invention
Figure 2 is a typical expanded graphite electron micrograph

Hereinafter, the present invention will be described in more detail with reference to Examples.

Example 1

As an alternative to crude oil, n-dodecane is used as the material to be absorbed.

An electron micrograph of an Enbarotech graphene ER-2510 manufactured by thermal shock of graphite oxide is shown in FIG. 1. It is shown that there are countless spaces between graphene layers.

Into a 5 L container, add 10 g of Enbarotech Graphene ER-2510 0.5 g n-dodecane with a multilayered graphene mixture, allow the oil to adsorb for 30 minutes, transfer it to a vacuum-filtered container, and filter. A negative pressure is applied for 10 minutes to remove the insufficiently adsorbed oil and the whole weight of the filter paper is weighed. The weight of the filter paper itself and the weight of graphene are subtracted from the total weight of the oil adsorbed to measure the amount of oil adsorbed on the adsorbent material. Calculate the adsorption rate as follows. Adsorption rates are summarized in Table 1 below.

Q = (filter paper, graphene and adsorption amount-filter paper and graphene) / graphene * 100 (%)

Comparative Examples 1 to 7

In Comparative Examples 1 to 7, instead of the multilayered graphene mixture, graphene (graphene made by chemical exfoliation without oxidation process) (Comparative Example 1) of the US XG science company (Comparative Example 1), graphene company of Graphene Super-Market, USA (High grade graphene with less than 10 layers made by chemical vapor deposition) (Comparative Example 2), Graphite QKG-296 (Comparative Example 3), QKG-299 (Comparative Example 4), Enbarotech Graphite Oxide of Qingdao Kropfmuehl, China Adsorption rates were summarized in Table 1 using GO-3510 (Comparative Example 5), expanded graphite (Comparative Example 6), and Hanwha Nanotech Carbon Nanotube (CNT) CM-95 (Comparative Example 7). An electron micrograph of expanded graphite (Comparative Example 6) of Samjung C & G is shown in FIG. Unlike in FIG. 1, no gap is visible between graphene layers.

Adsorption test using n-dodecane Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Comparative Example 7 Graphene (graphite oxide thermal shock) Graphene (chemical exfoliation without oxidation) Grapina black smoke black smoke Graphite oxide Expanded graphite Carbon nanotubes Material used (unit, gram) Nvarotech Graphene,
ER-2510 XG science
(United States of America) Graphene
Super-
Market
(United States of America) Qingdao
Kropfmuehl
Graphite
QKG-296 Qingdao
Kropfmuehl Garphite
QKG-299 Envarotech, GO-3510 Samjung C & G
ES-100 Hanwha
CM-95 Appearance Accordion Structure, FIG. 1 More than 20 floors Chemical vapor deposition more than 99% of carbon 96% or more of carbon, 0.37 specific gravity More than 99% of carbon, specific gravity 0.23 55% carbon, 40% oxygen,
Average particle size 100㎛ 95% or more carbon, average particle size 100㎛ Manufactured by chemical vapor deposition, more than 95% carbon, diameter 10-15nm Amount of oil adsorbed (g) 1.431 0.077 0.424 0 0 0 0.715 0.748 Adsorption rate (Q) 1,200 0 100 0 0 0 500 400

Graphite oxide has little oil adsorption effect, and expanded graphite or carbon nanotubes show some degree of oil adsorption. Graphene mixtures by thermal shock show twice as much oil adsorption as expanded graphite or carbon nanotubes.

Comparative Example 8

Water was poured into a container, crude oil was poured onto the water, and a commercially available adsorption cloth (Sejong, SJ-M100) was dipped to measure the amount of oil adsorbed by the adsorption fabric. No filter paper was used and the adsorption rate was calculated by subtracting the weight of the adsorption cloth from the total adsorption amount as in Example 1. The results are summarized in Table 2.

Example 2

Performed as in Comparative Example 8, but the graphene was placed in a tea bag bag to make an adsorption cloth. Oil absorption was measured. The results are summarized in Table 2.

The commercial oil adsorption cloth adsorbs crude oil about 7 times its own weight, but it shows that when enbarotech graphene is wrapped in a tea bag and adsorbed in a similar manner to the adsorption cloth, it adsorbs more than 65 times the weight of graphene used.

crude oil ( crude oil Adsorption Experiment Using Oil Comparative Example 8 Example 2 Absorbent cloth Sejong, SJ-M100 Weight (g) Enbarotech Graphene, ER-2510 Weight (g) Absorbent cloth weight before test, M1 0.395 Absorbent cloth weight after test, M2 3.292 The amount of oil adsorbed on the absorbent cloth 2.897 Tea Bag x 5 Weight 1.63 Amount of graphene used, M 0.10 Amount of oil adsorbed on tea bag, M1 7.90 Amount of oil after adsorption, M2 14.77 The amount of oil adsorbed by graphene 6.87 Adsorption rate (Q) 730% 6,550% (M2-M1) / M1 (M2-M1) / M

Claims

Multilayer graphene mixture for adsorption of organic substances obtained by thermal shock through a fluidized bed furnace having a carbon / oxygen ratio of 1 to 50/1 and an expanded interlayer distance maintained at 300 ° C to 1,200 ° C

The graphene oxide has a carbon / oxygen ratio of 1 to 50/1 by an element analyzer and a maximum peak near 2θ = 10 ° by X-ray diffraction analysis, and the graphene mixture has an average surface area of 200 to 2600. Multilayer Graphene Mixture for Adsorption of Organic Matter at m ² / g

The multilayer graphene mixture of claim 1, wherein the organic material is crude oil.

The carbonized oxygen oxide was passed through a fluidized bed maintained at 300 ° C to 1,200 ° C through an expanded graphite oxide having a carbon / oxygen ratio of 1 to 50/1, followed by compression molding by mixing a binder with a multilayer graphene mixture obtained by thermal shock. Packed Crude Oil Adsorbent