KR101802129B1 - Method for modification of carbon based materials using surfactant and surfactant modified carbon based materials - Google Patents

Abstract

The present invention provides a method for surface-modification of carbon based materials with a surfactant and to surfactant-surface modified carbon based materials, wherein the method for surface-modification of carbon based materials using the surfactant and irradiation has the following properties: 1) the method is very simple by using only the surfactant and irradiation compared to a modification method using chemicals such as nitric acid, sulfuric acid, hydrogen peroxide and the like; 2) the method improves stability by inducing chemical bonding rather than physical bonding; 3) the method adjusts the content of each component, the type of radiation and an irradiation method to modify the surface of a carbon-based material appropriately depending on physicochemical properties required in an application field.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of surface-modifying a carbon-based material with a surfactant and a carbon-based material surface-modified with a surfactant,

The present invention provides a method of surface-modifying a carbon-based material with a surfactant and a carbon-based material surface-modified with a surfactant.

Activated carbon, which is widely used as a carbon-based material, has a wide surface area and a specific pore structure, and is widely used in the industry as an adsorbent. Activated carbon is mainly used to carbonize raw materials such as palm shell, palm shell, lignite, bituminous coal, charcoal, anthracite coal, and petroleum at high temperatures and activate it with oxidizing gases such as steam, carbon dioxide, air or chemicals such as zinc chloride, phosphoric acid and sulfuric acid Is being produced.

Commercial activated carbons have various adsorption characteristics according to raw materials used, activation methods and processes, and their use is different according to their adsorption characteristics, and the price of activated carbon also has a considerable difference. Therefore, there is a continuing demand for the production of high-value-added activated carbon which selectively enhances the adsorption performance on the whole or specific substances by modifying the surface characteristics of the activated carbon, and various attempts have been made for this purpose.

In order to improve the adsorption performance of activated carbon, methods of modifying activated carbon surfaces to produce useful functional groups such as carbonyl group, carboxyl group and amine group, or increasing the specific surface area are mainly used, and the following methods are typically used.

It is possible to improve the adsorption performance for a specific substance by forming a functional group useful for adsorption such as an acidic functional group and an amine group on the activated carbon surface by immersing activated carbon in a chemical such as nitric acid, sulfuric acid, hydrogen peroxide for a certain period of time, In the United States.

There is proposed a method of generating a plasma containing a large amount of chemically active species and exposing activated carbon to the generated plasma for a certain period of time to generate useful functional groups on the activated carbon surface or changing the surface pore structure.

It is also known that plasma is generated in a vacuum atmosphere and the activated carbon is exposed to plasma for a predetermined time to modify the surface characteristics of the activated carbon to increase the electrical characteristics and specific surface area of the activated carbon.

A method of injecting activated carbon to be treated into a dielectric barrier discharge device under atmospheric pressure and generating oxygen plasma at a low temperature while supplying oxygen to modify the surface of activated carbon to improve the adsorption performance of metal ions.

However, the surface modification treatment method of activated carbon using a chemical is a method in which a large amount of waste such as a cleaning waste solution generated in a washing process to remove a residual chemical solution not used in the reforming reaction after treatment and a chemical solution remaining on the surface of the activated carbon And the useful pore structure of the activated carbon is destroyed by some excessive chemical reaction, which degrades the useful adsorption capability of the activated carbon before the treatment.

Accordingly, the present inventors have found that, by adding a carbon-based material and a surfactant to a solvent to irradiate a micelle-induced solution centering on a carbon-based material, the free radicals formed in the hydrophobic carbon chain of the surfactant react with carbon- And the present invention has been completed.

Korean Laid-Open Publication No. 10-2012-0054958

It is an object of the present invention to provide a method for surface modification of a carbon-based material with a surfactant.

Another object of the present invention is to provide a surface modified carbon based material produced by the above method.

Yet another object of the present invention is to provide an electronic device comprising the surface modified carbon-based material.

It is another object of the present invention to provide a filter comprising said surface modified carbon-based material.

It is still another object of the present invention to provide an activated carbon surface-modified with SDBS (sodium dodecylbenzenesulfonate) prepared by the above method.

Another object of the present invention is to provide a capacitive deionization (CDI) electrode comprising the surface-modified activated carbon.

In order to achieve the above object,

The present invention relates to a process for preparing a micelle-containing solution (step 1) by adding a carbon-based material and a surfactant to a solvent, And

Irradiating the solution prepared in step 1 above with radiation to induce formation of free radicals in the hydrophobic carbon chain of the surfactant and chemically bonding the free radicals to the surface carbon of the carbon-based material (step 2);

Wherein the carbon-based material is surface-modified with a surfactant.

The present invention also provides a surface modified carbon based material made by the above method.

Further, the present invention provides an electronic device comprising the surface-modified carbon-based material. Here, the electronic device may be an electrode (for example, a primary cell, a secondary cell, a capacitor, a supercapacitor, or an electrode used in a fuel cell), or the like.

The present invention also provides a filter comprising the surface modified carbon-based material. Here, the filter may be a cigarette filter, an air filtering filter, a water treatment filter, or the like.

Further, the present invention provides an activated carbon surface-modified with SDBS (sodium dodecylbenzenesulfonate) prepared by the above method.

The present invention also provides a storage-type desalination electrode comprising the surface-modified activated carbon.

The surface modification method of the carbon-based material using the surfactant and the irradiation of the radiation-

1) Compared with the conventional reforming method using chemicals such as nitric acid, sulfuric acid, and hydrogen peroxide, it is very simple because it uses only a surfactant and irradiation with radiation,

2) It is possible to induce chemical bonding, not physical bonding,

3) By controlling the content of each component, the kind of radiation and the irradiation method, it is possible to modify the surface of the carbon-based material appropriately according to the physicochemical properties required in the application field.

FIG. 1 is a flow chart showing steps of a method of surface-modifying a carbon-based material according to the present invention with a surfactant.
FIG. 2 is a graph showing the results of thermogravimetric analysis of activated carbon, surfactant, and surface-modified activated carbon used for measuring graft rate in the present invention.

Hereinafter, the present invention will be described in detail.

Carbon-based  As the surface active agent Surface modified  Way

The present invention relates to a process for preparing a micelle-containing solution (step 1) by adding a carbon-based material and a surfactant to a solvent, And

Irradiating the solution prepared in step 1 above with radiation to induce formation of free radicals in the hydrophobic carbon chain of the surfactant and chemically bonding the free radicals to the surface carbon of the carbon-based material (step 2);

Wherein the carbon-based material is surface-modified with a surfactant.

In the method according to the present invention, step 1 is a step of preparing a micellized solution around a carbon-based material by adding a carbon-based material and a surfactant to a solvent.

Step 1 may further include a crosslinking agent. When a cross-linking agent is added, the free radicals bond with the surface of the activated carbon and the cross-linking agent, so that the activated carbon surface graft rate of the surfactant is improved. That is, it can be added selectively when a high graft rate is required for the physicochemical properties required in the application field.

Examples of the cross-linking agent include divinylbenzene, 1,5-hexadiene-3-phosphorus, hexatriene, divinyl ether, divinylsulfone, allyl phthalate, 2,6-diacrylphenol and diallylcarbinol .

The carbon-based material may have a size of 1-1000000 nm, preferably 10-50000 nm, and more preferably 100-10000 nm. The carbon-based material may be activated carbon, carbon nanotubes, carbon nanofibers, graphite nanofibers, graphene, or the like, and preferably, particle-shaped materials may be used.

The surfactant may be an anionic surfactant, a cationic surfactant, an amphoteric surfactant, or a nonionic surfactant. In the present invention, the hydrophobic carbon chain of the surfactant is characterized in that free radicals are formed by irradiation, the free radicals are chemically bonded to the surface carbon of the carbon-based material, and the hydrophilic group exhibits the functionality required for the application field. That is, a surfactant having a hydrophilic head (functional group) necessary for an application field can be selected and used.

Preferable examples of the surfactant may be represented by the following general formula (1).

[Chemical Formula 1]

_{CH 3 - (CH 2) n} -R

In Formula 1,

n is an integer of 7-17,

R is a sulfate, an ether sulfate, an alkaryl sulfonate, a succinate, a sulfosuccinate, a phosphate, an ether phosphate, an ether carboxylate, an amino acid, a peptide, a carboxylic acid, a glutamate, an acylglutamate, or an amine.

Here, the substituent R may be in a salt form.

If the length of the hydrophobic carbon chain of the surfactant is less than C8 (n = 7), there may be a problem that the graft rate is significantly lowered, and if C18 (n = 17) is exceeded There is no problem in the graft rate, but as the molecular weight increases, the specific gravity of introducing the hydrophilic group of the surfactant, which imparts the functionality to the surface of the carbon-based material, decreases, and the cost of the surfactant of C18 or higher may increase. Here, in the case of a surfactant having a hydrophobic carbon chain length of less than C8, the formation of free radicals by irradiation is lowered or the degree of freedom of the carbon chain is lowered.

The solvent of step 1 may be water or an organic solvent. Here, as the solvent, a solvent capable of dissolving the surfactant can be appropriately selected and used. The organic solvent includes alcohols (such as methanol, ethanol, propanol, isopropanol, 1-butanol, 2-butanol, isobutanol, Etc.), aldehydes (such as formaldehyde), carboxylic acids (such as formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enantic acid, caprylic acid, pelargonic acid, capric acid, undecylic acid, lauric acid Dichloroethane, dichloroethylene, trichlorethylene, tetrachlorethylene, chlorobenzene, o-dichlorobenzene, etc.), amines (such as ethylenediamine, And the like), esters (such as methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, n-butyllithium, (Acetonitrile, etc.), ketones (such as acetone, methyl ethyl ketone (acetone, methyl ethyl ketone) and the like) MEK), methyl butyl ketone (MBK), methyl isobutyl ketone (MIBK), etc.), saturated and unsaturated hydrocarbons (hexane, kerosene, benzene, cyclohexane, toluene and xylene).

In the method according to the present invention, step 2 is a step of irradiating the solution prepared in step 1 above with radiation to induce the formation of free radicals in the hydrophobic carbon chain of the surfactant, Chemically bonding.

As the radiation, an electron beam or a gamma ray can be used.

For example, the solution of step 1 may be placed in a container having a wide bottom surface and a low height, and then the electron beam irradiation line may be passed once in about 4 seconds. You can investigate.

Since the gamma ray has a high transmittance, for example, the solution of Step 1 may be irradiated in a form such that gamma rays are transmitted through a drum-shaped container.

In Experimental Example 1 of the present invention, gamma rays are more excellent when comparing the graft rates of electron beams and gamma rays (see Table 1 and Table 2). For example, when activated carbon is used as the carbon-based material, the electron beam may be more advantageous than the gamma ray if the physical and chemical properties required for its application simultaneously require both porosity and surface functionality. If only the surface functionality is required, . For example, air or water treatment filters often require both porosity and surface functionality, so electron beams can be advantageous, and gamma-rays can be advantageous in the case of storage-type desalting electrodes because surface functionality is preferred over porosity.

Therefore, the surface modification method of the carbon-based material using the surfactant and the irradiation of the radiation according to the present invention can be applied to the surface-

1) Compared with the conventional reforming method using chemicals such as nitric acid, sulfuric acid, and hydrogen peroxide, it is very simple because it uses only a surfactant and irradiation with radiation,

2) It is possible to induce chemical bonding, not physical bonding,

3) By controlling the content of each component, the kind of radiation and the irradiation method, it is possible to modify the surface of the carbon-based material appropriately according to the physicochemical properties required in the application field.

As a surfactant Surface modified Carbon-based  Material

The present invention provides a surface modified carbon based material made by the above method.

The surface modified carbon based material according to the present invention is characterized in that the hydrophobic carbon chain of the surfactant is chemically bonded to the surface of the carbon based material and the hydrophilic group of the surfactant imparts a function to the surface of the carbon based material.

As the carbon-based material, activated carbon, carbon nanotubes, carbon nanofibers, graphite nanofibers, graphenes, and the like can be used. Particulate materials can be preferably used.

Electronic device

The present invention provides an electronic device comprising a carbon-based material surface-modified with the surfactant.

The electronic device may be a primary cell, a secondary cell, a capacitor, a super capacitor, an electrode used in a fuel cell, or the like, and may be applied to all electronic devices using a carbon-based material.

filter

The present invention provides a filter comprising a carbon-based material surface-modified with the surfactant.

The filter may be a cigarette filter, an air filtration filter, a water treatment filter, or the like.

SDBS (sodium dodecylbenzenesulfonate )in Surface modified  Activated carbon

The present invention provides an activated carbon surface-modified with SDBS (sodium dodecylbenzenesulfonate) as a surfactant prepared by the above method.

Here, as the surfactant, the hydrophilic group of SDBS imparts ion exchange functionality and can be useful for the following storage desalting electrode.

Condensation desalination (capacitive deionization) electrode

The present invention provides a storage type desalination electrode comprising activated carbon surface-modified with SDBS (sodium dodecylbenzenesulfonate).

In the case of capacitive deionization (CDI) electrodes which have been conventionally used, carbon electrodes, activated carbon and ion exchange membranes are sequentially laminated in the form of an ion exchange membrane, which is expensive, has a long processing process, .

In the case of the storage-type desalination electrode according to the present invention, since the surface-modified activated carbon is used with SDBS (sodium dodecylbenzenesulfonate) having ion exchange ability, not only expensive ion exchange membranes are used but also ion exchange capacity (IEC) is excellent.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the following examples are illustrative of the present invention, and the present invention is not limited by the following examples.

< Example  1> as a surfactant Surface modified  Production of activated carbon

The contents of each component used in the examples, the kind of radiation, and the intensity are shown in Table 1 below.

Step 1: Micellization  Preparation of solution

Micelles were formed around activated carbon by adding activated carbon (manufacturer: Gurray (Japan), model name: P-60, average particle size: 10 μm) and sodium dodecylbenzenesulfonate (SDBS) as a solvent as a solvent. Here, DVB (divinylbenzene) was selectively added as a crosslinking agent when it is necessary to improve the graft ratio of the surface active agent on the surface of activated carbon.

Step 2: Irradiation

Irradiation of the solution prepared in step 1 with electron beams (25 kGy / pass) or gamma rays (2 kGy / hr) was conducted to induce formation of free radicals in the hydrophobic carbon chains of the surfactant. The free radicals were chemically bonded Respectively. Here, when the crosslinking agent is added in Step 1, the free radicals bond with the surface of the activated carbon and the crosslinking agent to improve the activated carbon surface graft rate of the surfactant.

The electron beam was irradiated in the form of a line, and the solution of Step 1 was immersed in a container having a large bottom surface and low in height, and then irradiated with an electron beam irradiation line passing about once every 4 seconds. The gamma ray was irradiated in the form of a solution in which the solution of Step 1 was contained in a drum-shaped container and a gamma ray was transmitted.

Step 3: Unreacted  Removing and drying

After the irradiation treatment in the step 2, the unreacted surfactant and / or crosslinking agent was filtered out and dried to prepare activated carbon surface-modified with the desired surfactant.

Example Carbon-based
Material Surfactants Cross-linking agent menstruum radiation
Irradiation dose (kGy) Graft rate
(%) Activated carbon (g) SDBS (g) DVB (g) Water (g) Electron beam
(25 kGy / pass) Gamma ray
(2 kGy / hr) 1-1 0.1 0.1 0.01 15 100 - 29 1-2 0.1 0.2 0.01 15 100 - 31 1-3 0.1 One 0.01 15 100 - 41 1-4 0.1 0.1 0.03 15 100 - 43 1-5 0.1 0.2 0.03 15 100 - 49 1-6 0.1 One 0.03 15 100 - 64 1-7 0.1 0.1 0.05 15 100 - 32 1-8 0.1 0.2 0.05 15 100 - 36 1-9 0.1 One 0.05 15 100 - 39 1-10 0.1 0.1 - 15 100 - 31 1-11 0.1 0.2 - 15 100 - 30 1-12 0.1 One - 15 100 - 38 2-1 One 2 0.5 100 25 - 8 2-2 One 2 0.5 100 50 - 23 2-3 One 2 0.5 100 75 - 29 2-4 One 2 0.5 100 100 - 38 2-5 2 4 One 100 50 - 32 2-6 2 4 One 100 100 - 75 2-7 1.5 3 0.75 100 50 - 21 2-8 1.5 3 0.75 100 100 - 47 3-1 5 5 2.5 500 - 50 93.1 3-2 5 10 2.5 500 - 25 92.5 3-3 5 10 2.5 500 - 50 95.9 3-4 5 10 2.5 500 - 100 98.4 3-5 5 10 - 500 - 50 84.5

< Experimental Example  1> hydrophobic carbon chain of surfactant Graft rate  evaluation

To investigate the degree of chemical grafting of surfactant onto the surface of activated carbon, the following experiment was conducted.

Specifically, a thermogravimetric analysis (TGA) method was used to determine the graft rate of the surface-modified activated carbon prepared in the examples and the graft rate in the case of using a surfactant having a different hydrophobic carbon chain length.

In general, when the activated carbon surface is modified, all of the unreacted surfactants are removed during the washing process. Only the surfactant chemically bonded to the activated carbon surface is present in the form of char in the thermogravimetric analysis, thereby affecting the graft rate .

The grafting ratios in Examples are shown in Table 1, and the grafting ratios in the case of using other surfactants are shown in Table 2 below.

Carbon-based
Material Surfactants Cross-linking agent menstruum radiation
Irradiation dose (kGy) Graft rate
(%) Activated carbon (g) (g) DVB (g) Water (g) Electron beam
(25 kGy / pass) Gamma ray
(2 kGy / hr) 0.1 SHBS (C6)
One 0.03 15 100 - 12.1 0.1 SOBS (C8)
One 0.03 15 100 - 62.1 Example
1-6 0.1 SDBS (C12)
One 0.03 15 100 - 64 0.1 SHDBS (C16)
One 0.03 15 100 - 65.9 0.1 SODBS (C18)
One 0.03 15 100 - 66.2 5 SHBS (C6)
10 2.5 500 - 100 32.9 5 SOBS (C8)
10 2.5 500 - 100 97.1 Example
3-4 5 SDBS (C12)
10 2.5 500 - 100 98.4 5 SHDBS (C16)
10 2.5 500 - 100 98.6 5 SODBS (C18)
10 2.5 500 - 100 99.1 SHBS (sodium hexylbenzenesulfonate; C6)
SOBS (sodium octylbenzenesulfonate; C8)
SDBS (sodium dodecylbenzenesulfonate; C12)
SHDBS (sodium hexadecylbenzenesulfonate; C16)
SODBS (sodium octadecylbenzenesulfonate; C18)

As shown in Table 2, when the length of the hydrophobic carbon chain of the surfactant is more than C8, the graft rate is excellent, whereas when the surfactant is less than C8, the graft rate is remarkably decreased. These results suggest that the surfactant with a hydrophobic carbon chain length of less than C8 is reduced by the irradiation of free radicals and the degree of freedom of the carbon chain is lowered. Therefore, in the present invention, it has been found that it is preferable to use a surfactant having a hydrophobic carbon chain of C8 or more in order to improve the graft rate.

On the other hand, as shown in Table 1, the grafting rate of each example varied from 8 to 98.4%, and grafting rate was also found to be even in the case of the example not using the crosslinking agent. When the crosslinking agent was added The graft rate was slightly increased. Therefore, when the production method according to the present invention is used, the surface of a carbon-based material (for example, activated carbon) can be easily modified using only a surfactant.

Claims (16)

Adding a carbon-based material and a surfactant to a solvent to prepare a micellized solution around the carbon-based material (step 1); And
Irradiating the solution prepared in step 1 with radiation to induce free radical formation in the hydrophobic carbon chain of the surfactant and chemically bonding the free radical to the surface carbon of the carbon-based material (step 2);
Wherein the carbon-based material is surface-modified with a surfactant.
The method according to claim 1,
Wherein the step (1) further comprises a crosslinking agent.
The method according to claim 1,
Wherein the carbon-based material has a size of 1-1000000 nm.
The method of claim 3,
Wherein the carbon-based material is one selected from the group consisting of activated carbon, carbon nanotubes, carbon nanofibers, graphite nanofibers, and graphenes.
The method according to claim 1,
Wherein the surfactant is an anionic surfactant, a cationic surfactant, an amphoteric surfactant or a nonionic surfactant.
6. The method of claim 5,
Wherein the surfactant is represented by the following Formula 1:
[Chemical Formula 1]
_{CH 3 - (CH 2) n} -R
(In the formula 1,
n is an integer of 7-17;
R is a sulfate, an ether sulfate, an alkaryl sulfonate, a succinate, a sulfosuccinate, a phosphate, an ether phosphate, an ether carboxylate, an amino acid, a peptide, a carboxylic acid, a glutamate, an acylglutamate or an amine;
Wherein R may be in salt form.
The method according to claim 1,
Wherein the solvent is water or an organic solvent.
8. The method of claim 7,
Wherein the organic solvent is an alcohol, an aldehyde, a carboxylic acid, a chlorocarbon, an amine, an ester, an ether, a cyan, a ketone, or a saturated or an unsaturated hydrocarbon.
The method according to claim 1,
Wherein the radiation is an electron beam or a gamma ray.
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