KR101907969B1 - Ion selective carbon composite for desalinization carbon electrode, method for manufacturing thereof, and desalinization carbon electrode therefrom - Google Patents

Abstract

In the present invention, an electrode having ion selectivity capable of exhibiting selectivity for a specific ion by modifying a carbon surface is added to impart selectivity to a specific ion among various kinds of ions having the same charge, It is possible to selectively remove only a specific ion without using it.

Description

TECHNICAL FIELD [0001] The present invention relates to an ion selective carbon composite material for a desalting carbon electrode, a method for producing the same, and a desalination carbon electrode manufactured by the method.

The present invention relates to an ion selective carbon composite material for a desalting carbon electrode, a method for producing the same, and a desalted carbon electrode produced by the method. More particularly, the present invention relates to an ion selective carbon composite material having a specific ion The present invention relates to an ion selective carbon composite material for a desalted carbon electrode, and a desalted carbon electrode produced by the method.

In general, only about 0.0086% of all water on Earth is usable. This can not be overly generous if you consider the disaster caused by climate change. Water is very important in human life, and water is widely used as living water or industrial water. Water is polluted by heavy metals, nitrate nitrogen, fluoride ions, etc. due to industrial development, and it is very harmful to health when drinking contaminated water.

Recently, a variety of desalination techniques have been studied for purifying contaminated water and purifying seawater for use as a water source. This desalination technique is a technique of desalting by removing various suspended substances and ion components contained in contaminated water such as seawater and wastewater. As currently known nitrate removal methods, ion exchange, biological treatment, Reverse osmosis (RO), and electrodialysis (ED). Biological treatment is relatively inexpensive, but requires large-scale bioreactors. In addition, there is a problem that the removal efficiency is lowered due to the activity of the microorganisms in the winter when the water temperature is low. The ion exchange method is capable of removing nitrate ions by a simple method, but there is a disadvantage in that a large amount of secondary pollutants is discharged during the regeneration of the ion-exchanged resin. Reverse osmosis membrane and electrodialysis methods can effectively remove nitrate, but they have a disadvantage in that the membrane must be periodically replaced and the operation cost must be increased by applying a high pressure or voltage. In order to compensate for this, researches on capacitive deionization (CDI), which has a low energy consumption, are actively being conducted.

This CDI technology is characterized by a significant reduction in energy costs over conventional desalination technologies such as electrodialysis (ED) and reverse osmosis (RO). In addition, since it does not emit pollutants during operation, it is recognized as a desalination technology having an advantage in environmental aspect.

The CDI technique removes ions by adsorbing ions with opposite charges when the potential is applied to the porous carbon electrode. Therefore, in order to increase the desalination rate, it is important to increase the adsorption capacity of the carbon electrode itself. To this end, carbon electrodes for CDI using many types of carbon bodies have been developed. In the early 2000s, Andelman was able to dramatically improve the desalination efficiency of the CDI process by using membrane capacitive deionization (MCDI), which is a technique for selectively intercalating ions by combining an ion exchange membrane with a carbon electrode.

However, such an MCDI technique has a disadvantage in that it is economically disadvantageous to use an expensive ion exchange membrane sold in the market, and a contact resistance exists when the ion exchange membrane and the electrode are combined. Therefore, recently, a technique for manufacturing an ionic membrane having ion selectivity by using a polymer material and an inorganic material has been attracting attention. At this time, depending on the functional group of the membrane, it is divided into cation exchange membrane and anion exchange membrane. Cation exchange membrane is _{^{-SO 3 -, -COO -, -PO}} 3 2-, -PO 3 H -, -C 6 H 4 O - , etc. It has a negatively charged functional groups, and selectively transmits a cation, an anion exchange membrane is -NH ₃ ⁺ , -NRH ₂ ⁺ , -NR ₂ H ⁺ , -NR ₃ ⁺ , -PR ₃ ⁺ , and -SR ₂ ⁺ , and selectively permeates anions.

Japanese Patent Application Laid-Open No. 10-2010-0082977 (July 21, 2010)

Disclosure of the Invention The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to improve the storage capacity by coating a metal on a carbon surface to impart selectivity to a specific ion among various kinds of ions having the same charge, Ion selective carbon composite material for a desalted carbon electrode capable of selectively selecting only specific ions by forming an ionic membrane through a sulfonic acid group having ion selectivity capable of exhibiting selectivity for a desalted carbon electrode, The purpose is to provide.

It is another object of the present invention to provide a desalted carbon electrode in which the manufacturing process is simplified by directly modifying the carbon surface to produce a carbon electrode.

The present invention also provides a desalination apparatus capable of efficiently separating and removing specific cations or specific anions, having ion selectivity without containing a separate ion exchange membrane through the desalted carbon electrode according to the present invention, .

In order to solve the above-mentioned problems, the present invention provides a method of manufacturing a carbon composite material, comprising: preparing a first carbon composite material comprising a metal oxide bonded on a surface of a carbon powder; Preparing a second carbon composite material having a sulfonated group introduced into the metal oxide of the first carbon composite material; And mixing the second carbon composite material and the binder to produce an electrode.

According to one preferred embodiment, the carbon may include at least one selected from the group consisting of activated carbon powder (ACP), activated carbon, aerogel carbon, carbon nanotubes, and graphene.

According to another preferred embodiment, the average particle diameter of the carbon powder may be 0.1 to 20 탆.

According to another preferred embodiment of the present invention, the step (1) further comprises a step of mixing the surface of the carbon powder with a first functional group selected from the group consisting of a hydroxyl group, a carboxyl group sulfonic acid group (SO ₃ ^- ) and a phosphoric acid group (PO ₃ H ^- ; And reacting the modified carbon powder with a precursor of the hydrated metal oxide.

Here, the sulfonated group may be introduced by reacting with a compound containing a sulfonate group and a metal oxide of the first carbon composite material.

According to another preferred embodiment, the solvent added to the step (3) is selected from the group consisting of di-methylacetamide and N-methyl-2-pyrrolidone And at least one selected from the group consisting of

According to another preferred embodiment, the carbon and the metal oxide may be contained in a weight ratio of 1: 0.01 to 1: 0.20.

According to another embodiment of the present invention, the binder may include at least one selected from the group consisting of polyvinylidene fluoride, and polytetrafluoroethylene.

According to another preferred embodiment, the metal oxide and the binder may be mixed in a weight ratio of 1: 0.05 to 1: 0.3.

According to yet another preferred embodiment, the metal oxide is selected from the group consisting of titanium dioxide (TiO ₂ ), silicon dioxide (SiO ₂ ), zinc oxide (ZnO), tin oxide (SnO ₂ ) and aluminum oxide (Al ₂ O ₃ ) , And the sulfonating group includes at least one selected from the group consisting of sodium catecholate sulfonate (Tiron), poly (sodium-4 styrene sulfonate) (poly (sodium styrene sulfonate)), sulfonated poly (Ether ether ketone), and sulfosuccinic acid (SSA). [0027] The term " polyether ether ketone "

According to another aspect of the present invention, there is provided a desalted carbon electrode comprising a carbon powder and a carbon composite material, which is bonded to the carbon powder and contains a metal oxide having a sulfonated group introduced therein.

According to one preferred embodiment, the metal oxide into which the sulfonate is introduced may be a reactant between the metal oxide and the compound containing the sulfonating group.

Further, the present invention relates to a carbon powder; And a metal oxide, which is bound to the carbon powder and into which a sulfonated group is introduced, to provide an ion selective carbon composite material for a desalted carbon electrode.

The present invention also provides a method for producing a carbon composite material, comprising the steps of: preparing a first carbon composite material comprising a metal oxide bonded on a surface of a carbon powder; And preparing a second carbon composite material having a sulfone group introduced into the metal oxide of the first carbon composite material. The present invention also provides a method for producing an ion-selective carbon composite material for a desalted carbon electrode.

Hereinafter, terms used in the present invention will be described.

As used herein, the term " sulfonating group " means containing a compound containing a sulfonating group to sulfonate the surface of the metal oxide.

The term " sulfoniazation " used in the present invention means that not only the sulfonation group is directly bonded to the metal oxide but also the compound including the sulfonation group is bonded to the metal oxide.

In addition, the electrode related terms used in the present invention are shown below.

(1) ACP (Activated Carbon powder): Activated carbon powder.

(2) CDI (Capacitive deionization): Condensation desalination process.

(3) AEM (anion exchange membrane): Anion exchange membrane.

(4) CEM (cation exchange membrane): Cation exchange membrane.

(5) MCDI (membrane capacitive deionization): Membrane storage desalination process.

The method for producing a desalted composite electrode according to the present invention comprises forming an ionic film having ion selectivity capable of exhibiting selectivity for a specific ion on a carbon surface in order to impart selectivity to a specific ion among various ions having the same charge , It is possible to selectively remove only specific ions.

In addition, the present invention can simplify the manufacturing process of the electrode by preparing the carbon electrode directly in slurry form by modifying the carbon surface so as to have ion exchange ability.

In addition, the desalination apparatus including the desalination carbon electrode of the present invention has ion selectivity without containing a separate ion exchange membrane, and can efficiently separate and remove specific cations or specific anions.

1 is a conceptual diagram illustrating a process of synthesizing ACP, TiO _2, and Tirron according to an embodiment of the present invention.
FIG. 2 is a flow chart showing a process of TiO ₂ coating on an ACP surface according to an embodiment of the present invention.
FIG. 3 is a flow chart illustrating a process of modifying a TiO ₂ / ACP surface using Tiron according to an embodiment of the present invention.
4 is a graph showing a CV measurement result of a battery according to an embodiment of the present invention.
5 is a conceptual view illustrating an assembly structure of a battery cell according to an embodiment of the present invention.
6 is a conceptual diagram illustrating a method of measuring a full cell using a battery cell according to an embodiment of the present invention.
7 is a graph showing FT-IR analysis results according to an embodiment of the present invention.
8 is a graph showing the results of ion exchange capacity (IEC) evaluation according to an embodiment of the present invention.
9 to 11 are graphs showing the results of TGA analysis according to an embodiment of the present invention.
12 and 13 are photographs showing the results of TEM and EDS according to an embodiment of the present invention.
14 to 18 are graphs showing CV measurement results of a battery according to an embodiment of the present invention.
19 and 20 are graphs showing the results of EIS measurement of an electrode according to an embodiment of the present invention.
FIGS. 21 and 22 are graphs showing the results of the measurement of the salt removal efficiency according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art can easily carry out the present invention. It should be understood, however, that the embodiments are not intended to limit the scope of the present invention, which should be construed to facilitate understanding of the present invention.

As described above, the conventional techniques for producing the desalination composite carbon electrode have a problem that the cost is low due to the use of an expensive ion exchange membrane, and the contact resistance exists when the ion exchange membrane and the electrode are combined.

Accordingly, the present invention provides a method of manufacturing a carbon composite material, comprising: preparing a first carbon composite material containing a metal oxide bound on a surface of a carbon powder to improve ion exchange capability; Preparing a second carbon composite material having a sulfonated group introduced into the metal oxide of the first carbon composite material; And a step of mixing the second carbon composite material and the binder to prepare an electrode. The present invention has been made to solve the above-mentioned problems.

As compared with the conventional method for producing desalted composite carbon electrodes, it is possible to modify the carbon surface directly without using expensive ion exchange membrane and to have ion selectivity to exhibit selectivity to specific ions, And the ion exchange capacity can be greatly improved.

Further, by manufacturing the electrode directly in the form of a slurry by modifying the carbon surface so as to impart ion exchange ability, the manufacturing process can be simplified.

Hereinafter, a method for manufacturing an electrode by modifying a carbon surface by the method for producing a desalted carbon electrode according to the present invention will be described in detail, but it is not limited thereto.

First, the step of preparing a first carbon composite material containing a metal oxide bonded on the surface of a carbon powder will be described.

The carbon according to the present invention may be bonded to at least one carbon selected from the group consisting of activated carbon powder (ACP), carbon black, carbon nanotube, and graphene. Preferably an activated carbon powder or a carbon nanotube, and more preferably an activated carbon powder.

Particularly, according to the present invention, the average particle diameter of the carbon powder may be 0.1 to 20 탆. Preferably 0.5 to 10 mu m, and more preferably 1 to 5 mu m. If the average particle diameter of the carbon powder is less than 0.1, the formed carbon electrode layer may be too dense and diffusion of the electrolyte into the electrode may be difficult. If the average particle diameter of the carbon is more than 20 탆 It is difficult to manufacture a thin electrode having a thickness of about one hundred microns and the outer surface area of the electrode is considerably reduced, thereby deteriorating the performance of the carbon electrode itself. Therefore, the above range is preferable.

Specifically, the first carbon composite material is prepared by coating the surface of the carbon powder with the metal oxide. When the functional groups on the surface of the carbon powder and the functional groups of the metal oxide are bonded to each other, Can be improved.

In this regard, FIG. 12 shows photographs showing the results of the TEM and EDS, and in particular, as shown in FIG. 12 (a), it can be seen that the carbon surface is coated with TiO ₂ .

It is also confirmed from FIG. 12 (c) and FIG. 12 (d) that O and Ti are bonded on carbon, and that S is uniformly distributed on O and Ti, .

In addition, FIG. 2 illustrates a process in which TiO ₂ is coated on the surface of activated carbon powder according to the present invention. The process of coating the carbon powder of FIG. 2 with TiO ₂ will be described in more detail in the following Example 1.

On the other hand, the metal oxide has a large surface area and relatively chemically stable capacity in an aqueous solution, and is not particularly limited as long as it has a hydrophilic property and a very small resistance and has a high speed characteristic. As a specific example, the metal oxide may be TiO ₂ , ZrO ₂ , ZnO, Al ₂ O ₃ , SiO ₂ , SnO ₂ , MnO, FeO, CoO, NiO, and CrO.

Preferably, the metal oxide may comprise titanium dioxide (TiO ₂ ) or silicon dioxide (SiO ₂ ), and more preferably titanium dioxide (TiO ₂ ).

In addition, according to the present invention, the average particle diameter of the metal oxide may be 0.02 to 10 탆. Preferably 0.02 to 5 mu m, and more preferably 0.05 to 0.5 mu m. If the average particle diameter of the metal oxide is 0.02 mu m or less, it may be difficult to produce particles. If the average particle diameter of the metal is 10 mu m or more, the surface area may be small, Therefore, the above range is preferable.

Article selected from the group consisting of More specifically, according to the present invention, the first step for producing the carbon composite is a surface of the carbon powder, a hydroxy group, a carboxyl group, a sulfonic acid group (SO ₃ ^{- -)} and a phosphoric acid group (PO ₃ H) 1 functional group; And reacting the modified carbon powder with a precursor of the hydrated metal oxide.

When the metal oxide is a metal oxide including titanium dioxide (TiO ₂ ), the hydrated metal oxide precursor may include a titanium alkoxide compound. In a specific example, the metal oxide precursor may include titanium isopropoxide Titanium (IV) isopropoxide: TTIP).

In this regard, FIG. 1 illustrates an exemplary process in which the metal oxide is treated on the carbon powder to impart ion exchange capability. As shown in FIG. 1, the first carbon composite material preferably has a hydration reaction under the condition that a low pH concentration with the hydroxy group of the pretreated carbon is maintained, and the titanium isopropoxide having an OH-Ti-OH form TTIP). ≪ / RTI >

According to the present invention, the carbon and the metal oxide may be mixed in a weight ratio of 1: 0.01 to 1: 0.20. Preferably, the carbon and the metal oxide may be mixed in a weight ratio of 1: 0.03 to 1: 0.15, more preferably 1: 0.05 to 1: 0.10. When the metal oxide is added in an amount of less than 0.01 wt%, there may be a problem that the ion exchange ability of the electrode is remarkably lowered due to a small amount of metal to which the ion exchange functional group can be added, and when the metal oxide is added in excess of 0.2 wt% There is a problem that too much metal oxide adheres to the carbon itself, which may increase the electrode resistance or significantly reduce the non-storage capacity of the carbon.

In this connection, FIGS. 10 and 11 show TGA measurement results according to the content of titanium dioxide (TiO ₂ ). Here, the sulfonated metal oxide and a surface coating of carbon is, as can be confirmed that represents the conventional TiO ₂ / ACP Unlike the graph trend, identified in Figure 17, the addition of TiO ₂ as much as 0.75 mmol / gC ACP It can be seen that the capacitance is measured the greatest.

As can be seen from FIG. 19 (c), the inclination tends to be gentle with respect to the frequency of 0.1 Hz. When the TiO ₂ is added by 0.75 mmol / gC, the largest capacitance is again confirmed .

Next, the step of preparing the second carbon composite material having the sulfone group introduced into the metal oxide of the first carbon composite material produced as described above will be described.

Specifically, the second carbon composite material is formed by modifying the carbon surface treated with the metal oxide with a compound containing a sulfonate group. As shown in FIG. 2, after the first carbon composite material is produced, And the OH of the compound containing Ti-OH and the sulfonated group is formed by bonding by a condensation reaction.

Here, the sulfonate group may be introduced by reacting with a compound containing a sulfonate group and a metal oxide of the first carbon composite material.

In this regard, an example of the reaction process of the above-mentioned carbon, metal oxide and compound containing a sulfonated group is shown in FIG. FIG. 1 shows the synthesis of titanium catecholate sulfonate (Tiron) having -SO ₃ ^- functional groups on titanium dioxide by coating a precursor of titanium dioxide (TiO ₂ ) on the functional groups of the surface of carbon through pretreatment of carbon As shown in FIG. That is, as described above, the -OH functional group is formed on the surface of carbon, and TTIP (Titanium (IV) isopropoxide), which is a precursor of titanium dioxide, is mixed with the -OH functional group to impart ion exchange ability.

Therefore, as for, identified in FIG. 7, 460 cm ^- can be seen that the peak appearing in the vicinity of ¹ and 1650 cm ^-1, it can be seen that due to the Ti and OH. Through this, it can be confirmed that Ti and OH are bonded.

In addition, FIG. 3 illustrates an exemplary process for modifying the surface of carbon and TiO ₂ using Tiron according to the present invention. The process of sulfonation of the carbon and TiO ₂ of FIG. 3 by Tiron will be described in more detail in Example 2 below.

Also, the second carbon composite material is prepared by treating the first carbon composite material with a mixture of a compound containing the sulfonated group and a solvent, wherein the solvent is an agent added to elute the metal ion of the metal oxide And is not particularly limited as long as it is a component capable of dissolving the metal oxide.

Therefore, the surface of the carbon is coated with the metal oxide, and the metal oxide is sulfonated with the compound containing the sulfonate group, thereby imparting selectivity to a specific ion among various kinds of ions, thereby improving the ion exchange capacity (IEC) Can be improved.

Meanwhile, according to the present invention, the carbon and the compound including the sulfonated group may be mixed at a weight ratio of 1: 0.05 to 1: 1.0. Preferably, the carbon and the compound containing the sulfonated group may be mixed at a weight ratio of 1: 0.1 to 1: 0.8, more preferably the compound containing the carbon and the sulfonated group at a weight ratio of 1: 0.3 to 1: Lt; / RTI > When the compound containing the sulfonate group is added in an amount of less than 0.05 part by weight, oxide particles having a low ion exchange ability may be formed. When the compound containing the sulfonate group is added in an amount exceeding 1.0 by weight There may be a problem that metal particles having a low ion exchange ability can be produced because the sulfone groups attached to the surface are reduced due to mutual cohesion of sulfonated functional groups.

In this connection, as can be seen in FIG. 8, it can be seen that even when the amount of thiron is increased, the equivalent amount is kept constant, so that if the amount of thiron is above a certain level, equilibrium is reached, It can be seen that the paging is not performed.

Further, as shown in Fig. 12 (b), it is possible to confirm that the Tiron functional group is attached to the TiO ₂ surrounding the carbon by the difference in the color concentration depending on the thickness.

Also, the compound containing a sulfonate group is added to sulfonate the metal oxide to bind with the metal ion. In a specific example, the compound containing a sulfonate group is a compound having a cationic functional group or a polymer, Sodium sulfonate (Tiron), Poly (sodium-4 styrene sulfonate), Sulfonated Poly (ether ether ketone) (Sulfonated PEEK) And sulfosuccinic acid (SSA). Preferably, the sulfonating agent is at least one selected from the group consisting of sodium catecholate sulfonate (Tiron) and sulfosuccinic acid (SSA) , And more preferably sodium catecholate sulfonate (Tiron).

The compound containing a sulfonate group may be a sulfonic acid group (-SO ₃ H), a carboxyl group (-COOH), a phosphonic group (-PO ₃ H ₂ ), a phosphonic group (-HPO ₂ H) -AsO ₃ H ₂ ) and a selinolytic group (-SeO ₃ H).

In this connection, FIG. 18 (b) shows the result of measurement with TiO ₂ / ACP 0.75 attached with a Tiron functional group, wherein it can be seen that the capacitance at the cathode is measured to be larger than that at the anode. Therefore, it can be judged that the compound containing the sulfonated group is suitable for an electrode having cationic selectivity.

(NH ₂ ), a primary to tertiary amine (-NH ₂ , -NHR, -NR ₂ ) may be used when the compound containing the sulfonate group is a compound or polymer having an anionic functional group, , A quaternary phosphonium group (-PR ₄ ), and a tertiary sulfonium group (-SR ₃ ). Such a polymer resin may be present in the form of a solution in the form of a solution in the form of a solution in an organic solvent. Examples of the polymer resin include polystyrene, polysulfone, polyisocyanurate, polyamide, polyester, polyimide, polyether, polyethylene, polytetrafluoroethylene, Glycidyl methacrylate, and mixtures thereof. The resin is not limited to these, and any resins that can have a cation-exchange group or anion-exchange group can be used without limitation.

Further, in some cases, the present invention also includes an aminated metal oxide by an aminating agent in addition to the sulfonated metal oxide by the above-mentioned sulfonating agent. As the amineifying agent for aminating the metal oxide, an amine group amine group, or a polymer thereof. In a specific example, it may be 3-amino-prolyltriethoxysilane (APTES).

Finally, the step of preparing the electrode by mixing the second carbon composite material and the binder will be described.

Specifically, the electrode may be manufactured as a slurry in which the second carbon composite material and the binder are mixed with a solvent to form a slurry in which the functional group of the compound including the sulfonated group is combined with the metal oxide of the second carbon composite material to form an electrode .

Here, the binder is a polymer material having a low glass transition temperature and stable at room temperature and water, is uniformly mixed with the second carbon composite material, and is added so that a coating layer can be formed well. As a result, a polymer capable of thermal melting coating or solvent- The binder can be any type of material. Examples of the binder include polyvinylidene fluoride (PVdF), linear low density polyethylene (LLDPE), low density polyethylene (LDPE), polyethylene (PE), ethylene vinyl acetate EVA), polyolefin, polyamide, polyester, and polyurethane, but is not limited thereto.

According to the present invention, preferably, the binder may be polyvinylidene fluoride (PVdF) or polytetrafluoroethylene, more preferably polyvinylidene fluoride (PVdF) .

Also, according to the present invention, the metal oxide and the binder may be mixed in a weight ratio of 1: 0.05 to 1: 0.3. Preferably, the metal oxide and the binder may be mixed in a weight ratio of 1: 0.08 to 1: 0.2, and more preferably, the metal oxide and the binder may be mixed in a weight ratio of 1: 0.1 to 1: 0.15. When the binder is added in an amount of less than 0.05 wt%, the adhesion of the metal oxide layer may be deteriorated. When the binder is added in an amount exceeding 0.3 wt%, the resistance of the electrode itself And the ion exchange capacity of the metal oxide layer may be deteriorated. Therefore, the above range is preferable.

In addition, the solvent is not particularly limited as a component to be added so that the compound containing the second carbon composite material and the sulfonated group is dissolved, and organic solvents in which the polymer binder selected is determined depending on the type of the binder are all possible Examples of suitable organic solvents for the polymer binder include dimethylacetamide, dimethylformamide, diethylformamide, dimethyl carbonate, ethylene carbonate, ethylmethyl carbonate, diethyl carbonate, propylenecarbonate, acetonitrile, It is possible to use one or a mixture of two or more selected from the group consisting of money, acetone, chloroform, dichloromethane, trichlorethylene, ethanol, methanol, isopropanol, propanol and hexane.

According to the present invention, the solvent may include at least one selected from the group consisting of di-methylacetamide and N-methyl-2-pyrrolidone. , And more preferably dimethylacetamide (DMAc).

According to another aspect of the present invention, there is provided a desalination carbon electrode comprising a carbon powder and a carbon composite, which is bonded to the carbon powder and includes a metal oxide into which a sulfonated group is introduced, and a desalination apparatus comprising the same.

Here, the metal oxide into which the sulfonated group is introduced may be a reaction product between a compound containing a sulfonated group and a metal oxide.

In this connection, the description of the carbon and the sulfonated metal oxide, which is a metal oxide into which the sulfonated group is introduced, is as described above, so that the description of overlapping portions is omitted.

 According to the present invention, the desalination apparatus including the desalination carbon electrode does not include a separate ion exchange membrane. Therefore, the ion exchange ability can be improved by modifying the carbon surface with the sulfonated metal oxide by using a sulfonated group without using an expensive ion exchange membrane.

In this connection, FIG. 20 shows the EIS measurement result of the electrode having TiO ₂ / ACP 0.75 attached with the Tiron functional group. As shown in FIG. 20 (b), the coated carbon coated with the Tiron functional group It can be seen that the electrode is more excellent in resistance.

Further, according to the present invention, carbon powder; And a metal oxide bonded to the carbon powder and having a sulfonated group introduced thereinto, and an ion selective carbon composite material for a desalted carbon electrode.

The ion-selective carbon composite material for desalted carbon electrode may be a second carbon composite material produced during the production of the desalted carbon electrode, and may be prepared through the steps (1) and (2) described above .

Hereinafter, exemplary embodiments of the present invention will be described in order to facilitate understanding of the present invention. However, the following examples are intended to aid understanding of the present invention, and the present invention is not limited by the following experimental examples.

[Example]

<Example 1> TiO ₂ coating on the surface of ACP

First, 10 g of ACP (activated carbon powder) and 200 ml of ethanol were added as a base to coat TiO ₂ on activated carbon powder (ACP). Next, in order to find the optimum point for TiO ₂ coating on ACP (Activated Carbon Powder), TiO ₂ The amount of TTIP (Titanium (IV) isopropoxide), which is a precursor material, was added while changing the amount of TTIP.

division Sample name ACP EtOH TTIP Theoretical TiO ₂ [g] [mmol] [g] [mmol / g-C] Example 1 TiO ₂ 0.75 10 200 2.29 0.75 Example 1-1 TiO ₂ 1.00 10 200 3.05 1.00 Examples 1-2 TiO ₂ 1.25 10 200 3.82 1.25

Each sample was put in accordance with the composition of Table 1 and stirred for 1 hour. 10 ml of HCl was then added to make the acid atmosphere and stirred at 45 &lt; 0 &gt; C for 24 hours. Finally, to obtain coated carbon, TiO ₂ / ACP was prepared by vacuum filtration using a rotary and drying in a 40 ° C oven overnight. This process is shown in Fig. 2 below.

<Example 1-1 ~ 1-2> TiO ₂ coating on the surface of ACP

Activated carbon powder (ACP) was coated with TiO ₂ in the same manner as in Example 1 except that the composition ratio was changed to the above Table 1.

&Lt; Example 2 > Surface modification of TiO2 / ACP using Tiron

In order to attach the Tiron functional group to the TiO ₂ / ACP prepared in Example 1, 500 ml of a solution having a pH of 2 was prepared by adding HCl to distilled water. Next, TiO ₂ / ACP (5 g) was mixed with 200 mL of a solution of pH 2 and ultrasonically dispersed for 2 hours. The remaining 300 ml of the solution having a pH of 2 was added with Tiron powder according to the weight% ratio and stirred until it dissolved. The weight% compositional table at this time is shown in Table 2 below.

division Sample name Tiron / carbon [wt. ratio] Tiron pH 2 solution [wt. ratio] [g] [ml] Example 2 Tiron 0.10 0.10 5 0.50 500 Example 3 Tiron 0.30 0.30 5 1.50 500 Example 4 Tiron 0.50 0.50 5 2.50 500 Example 5 Tiron 0.70 0.70 5 3.50 500

Next, TiO ₂ / ACP and Tiron dispersed in a solution of pH 2 were mixed with each other and stirred for 30 minutes or more. The stirred solution was then poured into a vacuum filtration apparatus, washed with distilled water until the pH reached 7, and the obtained powder was placed in an oven and dried at 40 ° C. This process is schematically shown in FIG. 3 below.

Examples 3 to 5 Carbon electrode fabrication

TiO ₂ / ACP surface modification using Tiron was performed in the same manner as in Example 2, except that the composition ratio was changed as shown in Table 2.

&Lt; Example 6 > Carbon electrode fabrication

To prepare a carbon electrode using activated carbon powder (ACP), TiO ₂ / ACP, and TiO ₂ / ACP + Tiron powder, DMAc and polyvinylidene were first stirred at a weight ratio of 9: 1 for one day I made 10% PvdF which is a binder. 3.33 g of DMAc as a solvent and 4.6 g of a binder PvdF were added to each ACP, TiO ₂ / ACP, and TiO ₂ / ACP + Tiron powder on the basis of 3 g, and mixed using a Centrifugal mixer at 2000 RPM for 15 minutes Thereby producing a slurry which was not loosened even when a voltage was applied to the carbon electrode.

The slurry thus prepared was loaded on graphite in an appropriate amount and casted using a doctor blade of 300 占 퐉, followed by drying for 2 hours so that DAMc could be sufficiently evaporated in an oven. The thickness of the pure carbon electrode prepared after drying was measured to be about 140 to 150 탆.

[Experimental Example 1] Evaluation of surface functional groups

1. Evaluation of ion exchange capacity (IEC)

To evaluate the ion exchange capacity of TiO ₂ / ACP and Tiron, TiO ₂ / ACP + Tiron, 0.5 g each, was added to three vials and stored in 1.0 M HCl solution for one day. At this time, the H ⁺ of the HCl solution was attached to the functional group and changed into the H-form, and the solution was washed with distilled water until the pH became 7 to remove the unfixed solution. Next, 30 ml of each solution is stored in 0.1 M NaOH solution for one day to allow the H-form to be exchanged. The solution is filtered to collect 20 ml. Add the indicator phenolphthalein and titrate with 0.1 M HCl until neutral gave. This process is shown in FIG.

2. Evaluation of thermal gravity analysis (TGA)

TGA was performed to quantitatively analyze the amount of TiO ₂ coated on the ACP by analyzing the weight with temperature. Therefore, the temperature was increased from 0 ° C to 800 ° C in air at 10 ° C for 1 minute, and the ACP of the powder was burned by flowing the flow rate at 30 ml / min.

3. TEM / Elementary mapping / EDS evaluation

TEM is a technique for collecting electron beams passing through a sample to form an image. It was measured to see what kind of coating was formed on ACP. Elementary mapping was performed to check whether the elements of powder were uniformly distributed in ACP And EDS was measured for quantitative analysis of the powder produced.

4. Evaluation of CV (Cyclic Voltammetry)

Cyclic Voltammetry (CV), also called cyclic voltammetry, is used to analyze electrochemical properties. When a voltage of -0.5 V to 0.5 V is applied to the working electrode at a constant rate, the potential energy is changed, thereby oxidizing and reducing the sample dissolved in the solution. When the potential is scanned in the forward direction at the initial potential and the potential is reversely scanned at the conversion potential, one cycle is completed and the current with time is shown in FIG.

In FIG. 4, the right side of the potential indicates an anode, and the left side indicates a cathode. Anion adsorption and desorption processes occur at the anode, and adsorption and desorption processes occur at the cathode. In the ideal CV graph, the adsorption and desorption processes occur within a short time and show the shape of a rectangle. In actual measurement, however, both sides exhibit a symmetrical curve due to oxidation or resistance of the copper electrode. In this experiment, the scan rate was changed to 5, 10, 20, 40, 80, 100, and 120 mV, and each cycle was experimented with 5 cycles.

5. Electrical Impedance Spectroscopy (EIS) Evaluation

Electrical Impedance Spectroscopy (EIS), also referred to as impedance spectroscopy, is an analytical method for evaluating capacitance. It is an analyzer that measures the resistance of an electrode by applying a minute AC signal having different frequencies to a cell to change the wave number. In this experiment, the wave number was varied from 0.01 to 500 Hz, and the resistance at -0.2, 0, and 0.2 V was measured.

6. Evaluation of Full Cell (CDI, MCDI)

Full cell evaluation was performed by applying a potential to a carbon electrode to adsorb and desorb ions. After a stabilization time of 300 seconds, the adsorption potential at 1.0 V was applied for 360 seconds and the desorption potential was applied at 0 V for 360 seconds. Conductivity was measured. The electrical conductivity is an indicator of the current ion concentration. When adsorbed, the ions are attached to the electrode and the conductivity decreases. At the time of desorption, the ions attached to the electrode are separated and the conductivity is increased. This experiment was designed to circulate a 200 ml NaCl solution in a batch format. When the NaCl solution was flowed to the carbon electrode at a rate of 50 ml / min, the conductivity of the solution exiting the carbon electrode was measured, Allows you to see if it has been removed. At this time, the concentration of NaCl was changed to 400, 500 and 600 ppm to investigate the adsorption efficiency depending on the concentration. Respectively. FIG. 5 shows the cell assembly structure used in the experiment, and FIG. 6 shows a flow chart of the experiment.

[Experimental Example 2] Tendency of carbon composite electrode

1. Evaluation of ion exchange capacity (IEC)

Ion exchange capacity evaluation is an indicator of how much the H-form has been exchanged per g, and can be calculated using Equation (1) below. The calculated values are shown in Table 3 below. In order to obtain the equivalent weight, the amount of HCl solution used for titration is lower than that of 20 ml NaOH solution used for titration. However, in this experiment, it was confirmed that the amount of HCl solution was small in all the parameters.

[Formula (1)

V _NaOH : Volume of NaOH used in titration (ml)

N _NaOH : NaOH molarity (M)

V _HCl : HCl volume used in titration (ml)

N _HCl : HCl molarity (M)

Sample
Name Volume of NaOH solution before filtration (ml) NaOH solution volume (ml) Sample weight (g) HCl solution volume (ml) Ion exchange capacity (meq / g) Tiron 0.1 30.0 20.0 0.478 12.9 2.268 Tiron 0.3 30.0 20.0 0.407 13.8 2.320 Tiron 0.5 30.0 20.0 0.425 13.6 2.293 Tiron 0.7 30.0 20.0 0.496 12.6 2.277

Using Equation (3), the equivalence according to the amount of thiron added is shown graphically in FIG. 8 below. As a result, it can be seen that even when the amount of thiron is increased, the equivalent amount is constant. This is because if the amount of Tiron exceeds a certain level, equilibrium is reached. Therefore, in this experiment, the powder was prepared with Tiron 0.1, which is considered to be an excessive amount, and the experiment was conducted.

2. Fourier transform infrared spectroscopy (FT-IR) analysis

FT-IR spectrum analysis was performed in the range of scan number 16, resolution 4 cm ¹ , and wave number 4,000 ~ 1,000 cm ^-1 to confirm the binding structure of TiO ₂ and Tiron in ACP. The analysis result is shown in FIG. 8 below. Thus for The results 3460 cm ^-1 and 1650 cm ^- was confirmed that that the peak (peak) generated in the vicinity of ^1, which was found to be due to the Ti and OH. In this experiment, spectral analysis was performed to confirm that the TiO ₂ functional group, which is represented by the value [12] in the range of 1000 ~ 1500 cm ^-1, adhered well to TiO _2. The color of the prepared powder was too dark to transmit the light The measurement results were not obtained.

3. TGA analysis

TGA was measured to investigate the pyrolysis characteristics and the degree of TiO ₂ attached to the powder. First, FIG. 9 is a graph showing the measurement results of the TiO ₂ / ACP 0.75 powder before the heat treatment, in which the capacitance was the highest measured.

Next, the results of the TGA measurement when the content of TiO ₂ is varied and the heat treatment by nitrogen is performed are shown in FIG. 11 below. (a) is an example of the fraction after TiO ₂ / ACP 0.75 after heat treatment. As a result, the ACP was found to be 94.3983% and the residual fraction of TiO ₂ was found to be 5.0067%. To when it calculated by the following formula (2) may obtain the data according to the content of TiO ₂ of Table 4, more neulryeojul the content of TiO ₂ reduced the fraction of activated carbon powder (ACP), and the residue of TiO ₂ It can be seen that the fraction increases.

Therefore, as shown in the graph of FIG. 11 (b) using the data in the following Table 4, it can be confirmed once again that the remaining fraction increases as the content of TiO ₂ increases. In other words, through the comparison of the theoretical loading and the actual measurement loading, it can be seen that a similar result can be obtained through Table 4, and it can be seen that most of the measured load is slightly lower than the theoretical loading.

[Expression (2)]

χ: TiO ₂ weight (composition of TiO ₂ )

Mω: TiO ₂ molecular weight _{(molecular weight of TiO 2 (79.89} g / mol))

Y: ACP weight (composition of ACP)

Theoretical values (mmol / g-C) Composition (% by weight) Measured value (mmol / g-C) ACP TiO ₂ 0.00 100,000 0.000 0.000 0.75 94.398 5.007 0.664 1.00 92.708 6.697 0.904 1.25 90.063 9.343 1.299

Further, the TGA of the TiO ₂ / ACP + Tiron powder was measured and shown in FIG. The TGA graph of TiO ₂ / ACP + Tiron shows a tendency to be different from that of the conventional TiO ₂ / ACP. The reason for this is considered to be the change due to the addition of the pH 2 solution, ie, H ₂ O, which was used for attaching the Tiron functional group at 100 ° C. When the TGA was measured after removing it, the residual fraction was higher It is predicted that it will be possible.

4. TEM / Elementary mapping / EDS analysis

FIG. 13 (a) shows TEM results for TiO ₂ / ACP powders, and FIG. 13 (b) shows TEM results for TiO ₂ / ACP + Tiron powders. In addition, FIG. 13 (c) and Figure 13 (d), the TiO ₂ / ACP, TiO ₂ / ACP +, 13 exhibited a Elementary mapping results for Tiron powder (e) and 13 (f), the TiO ₂ / ACP, and TiO ₂ / ACP + Tiron powders.

Figure 13 (a) to look to see that it is coated with the ACP surface to form a TiO ₂ surrounding, and FIG. 13 (b) Tiron functional groups degree difference in color according to the thickness that is attached on the TiO ₂ surrounding the ACP through a . 13 (c) and 13 (d), it is confirmed that O, Ti, O, and S on the ACP are not partially scattered and distributed evenly. have.

13 (e) and FIG. 13 (f), S is measured only in the case of FIG. 13 (f) with the Tiron functional group, and it can be confirmed once again that the functional group is attached. Quantitative analysis showed that it was similar to 0.75 mmol / gC added at 0.77 mmol / gC.

5. CV (Cyclic Voltammetry) Evaluation Analysis

To determine the optimum amount of TiO ₂ to be coated on ACP, the amount of TiO ₂ was measured at 0.00, 0.75, 1.00 and 1.25 mmol / gC, respectively. FIG. 14 is a graph showing a value obtained by dividing the weight of pure carbon by the current measured according to the voltage. It can be seen that the slope of the graph increases as the speed of the graph increases. As the speed increases, the resistance increases and it is determined that the phenomenon occurs due to poor adsorption and desorption. The noncircuitable capacity for finding the optimum point of the coating was obtained by using the current according to the voltage from -0.5 V to 0.5 V. The method is shown in the following equation (3).

[Expression (3)]

C: Specific rectification

Ia: anode current

Ic: cathode current

v: scan speed

m: Carbon weight

In order to better understand the trend of the calculated non-volatile capacities, the average of each potential is shown in FIG. Next, FIG. 16 shows the non-discharging capacity according to the scan rate at -0.2, 0, and 0.2 V. FIG. The ideal graph has a constant non-linearity regardless of the speed, but it can be confirmed that the value of the non-linearity decreases as the speed of the measured graph increases.

Therefore, it can be seen that the performance of the electrode decreases as the speed increases, which is presumed to be the reason why the graph of FIG. 14 increases as the speed increases.

17 (a) and 17 (b) show values when the scan rate is 5 mV, and FIG. 17 (c) shows the integrated graph by comparing the non-discharge capacities by scan rate at -0.2 V . Referring to FIG. 17 (b), it was found that capacitance was the largest when ACP was coated with 0.75 mmol / gC of TiO ₂ . When the amount of TiO ₂ was more than 0.75 mmol / gC, it was confirmed that the capacitance was decreased because the excessive amount of the TiO ₂ was coated on the ACP and the resistance of the powder itself was increased. Therefore, in this experiment, it was judged that it is effective to attach the Tiron functional group to TiO ₂ / ACP 0.75 having the best performance for charging. In FIG. 17 (c), the problem that the non- It is judged that it is possible to have a constant value irrespective of the speed.

Thus, the result of measuring TiO ₂ / ACP 0.75 with a Tiron functional group is shown in FIG. 18 (a) and 18 (b) show the values when the scan rate is 5 mV, and in FIG. 18 (c), the values obtained when the scan rate is 5 mV are shown. And the nonvolatile capacity by the scan rate at 0.2 V was compared.

Here, as shown in Fig. 18 (b), it can be confirmed that the capacitance at the cathode is measured to be larger than the value at the anode. Therefore, it can be judged that the present invention is suitable for an electrode having a cation selectivity. As shown in FIG. 18 (c), it is confirmed that the change of the non-ionic capacity according to the speed is reduced by attaching the Tiron functional group.

In other words, it is more suitable for practical application because it can effectively adsorb and desorb ions in solution even at a high speed, and it can be confirmed that the charging ability of a TiO ₂ coated carbon electrode is superior to that of a TiO ₂ coated carbon electrode.

6. EIS evaluation analysis

The EIS was measured at -0.2, 0, and 0.2 V according to the addition amount of TiO ₂ . The method of determining the non-discharging capacity using the measured impedance is shown in the following equation (4).

[Expression (4)]

Cs: Specific capacitance

f: Frequency

Z ": charging resistance

ω: electrode weight

The values according to the above formula (4) are shown graphically in Fig. 19 (c). FIG. 19 (a) is a pure measurement result, and FIG. 19 (b) is an impedance measured while changing the frequency from 0.01 to 500 Hz at -0.2 V. FIG.

Referring to FIG. 19 (a), it can be seen that as the amount of TiO ₂ added increases, diffusion resistance caused by current diffusion increases. Referring to FIG. 19 (b), it can be seen that the slope increases sharply with respect to the frequency of 0.1 Hz. This means that the resistance is large, meaning that ions in the solution can not sufficiently enter between the pores.

That is, the slower the frequency, the more ions can pass through the pores. In FIG. 19 (c), the gradient tends to be gentle at a frequency of 0.1 Hz, and it can be confirmed once again that the capacitance is highest when TiO ₂ is added by 0.75 mmol / gC.

20 shows the result of EIS measurement of a TiO ₂ / ACP 0.75 electrode with a Tiron functional group, and also shows a graph comparing the result of adding a cation exchange membrane to a pure ACP electrode. The non-discharging capacity of Fig. 20 (c) was calculated using the above equation (4).

Also, referring to FIG. 20 (a), it can be seen that when a Tiron functional group is attached, diffusion resistance is measured to be smaller than when a cation exchange membrane is applied to a pure ACP. 20 (b), it was confirmed that the value of the charging resistance was smaller than that of the cation exchange membrane.

Therefore, although the performance is similar to that of the present experiment, it can be seen that the coated carbon electrode coated with the Tiron functional group is more excellent in resistance than the ion exchange membrane.

7. Measurement of salt removal efficiency

In order to investigate the salt removal efficiency, the cell assembly structure having the shape of FIG. 6 below was used in accordance with the experimental flow chart of FIG. Here, the NaCl solution was changed to 400, 500, and 600 ppm, and all the data obtained by measuring the adsorption and desorption times in six cycles of 360 seconds were shown in FIG. After the adsorption is abruptly performed, the value of the constant interval is maintained, and the desorption is abruptly maintained, and then it is maintained. The 200 ml NaCl solution is introduced into the carbon electrode at a rate of 50 ml / min. And the NaCl solution was circulated to maintain a constant concentration.

Also, it can be seen that the conductivity value is not constant and fluctuates because it is assumed that all concentrations in the solution are the same in an ideal batch, but in the experiment, the concentration is slightly different depending on the position.

In FIG. 22, only the fifth cycle of 6 cycles is shown separately. As shown in FIG. 22, the data of FIG. 22 (a) and FIG. 22 (b) all show a similar tendency.

Therefore, in order to easily grasp the data, the data of only the adsorption process is shown separately in FIG. 23 below. In particular, it can be seen that the graph does not fit the trend only in FIG. 23 (c), and it can be observed that the data value of Tiron + AEM + CEM is not constant. It is considered that the ion exchange membrane is not adhered to the carbon electrode and that the resistance between the electrode and the ion is increased as the AEM and CEM are added to the carbon electrode at the highest ion concentration of 600 ppm.

23 (a) and 23 (b), on the other hand, the adsorption performance of TiO ₂ / ACP + Tiron electrode and ACP electrode alone, that is, Tiron without cation and anion exchange membrane, You can see the most outstanding. Also, the rate of ion adsorption was the fastest at this time, presumably because of the cation selectivity of the TiO ₂ / ACP + Tiron electrode. Therefore, in order to improve the performance of Tiron, it is necessary to apply a cation exchange membrane. In this experiment, Tiron + AEM + CEM is not superior in performance.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. It will be apparent to those skilled in the art that the present invention, Various modifications and variations are possible.

Claims (14)

(1) preparing a first carbon composite material comprising a metal oxide bound on a surface of a carbon powder;
(2) reacting the metal oxide with a compound containing a sulfonate group to prepare a second carbon composite material having a sulfonated group introduced into the metal oxide; And
(3) mixing the second carbon composite material and the binder to prepare an electrode.
The method according to claim 1, wherein the carbon powder comprises at least one selected from the group consisting of activated carbon powder (ACP), activated carbon, aerogel carbon, carbon nanotube and graphene A method of manufacturing a carbon electrode.
The method of claim 1, wherein the carbon powder has an average particle size of 0.1 to 20 탆.
The method of claim 1, wherein the step (1)
Modifying the surface of the carbon powder with a first functional group selected from the group consisting of a hydroxyl group, a carboxyl group (COO ^- ), a sulfonic acid group (SO ₃ ^- ) and a phosphoric acid group (PO ₃ H ^- ); And reacting the modified carbon powder with a precursor of the hydrated metal oxide.

delete The method according to claim 1, wherein the solvent added to step (3) is at least one selected from the group consisting of Di-methylacetamide, N-methyl-2-pyrrolidone, And at least one selected from the group consisting of carbon black,
The method of claim 1, wherein the carbon powder and the metal oxide are contained at a weight ratio of 1: 0.01 to 1: 0.2.
The method of claim 1, wherein the binder comprises at least one selected from the group consisting of polyvinylidene fluoride, and polytetrafluoroethylene. .
The method of claim 8, wherein the metal oxide and the binder are mixed at a weight ratio of 1: 0.05 to 1: 0.3.
The method of claim 1, wherein the metal oxide is titanium dioxide (TiO _2), silicon dioxide (SiO _2), zinc oxide (ZnO), tin oxide (SnO ₂₎ and aluminum oxide (Al ₂ O ₃₎ from the group consisting of selected Wherein the compound containing at least one sulfonate group is at least one selected from the group consisting of sodium catecholate sulfonate (Tiron), poly (sodium-4 styrene sulfonate) (poly (sodium styrene sulfonate)), sulfonated poly Wherein the electrolyte comprises at least one selected from the group consisting of sulfonated poly (ether ether ketone) and sulfosuccinic acid (SSA).
A carbon composite comprising a carbon powder and a metal oxide which is bonded to the surface of the carbon powder and into which a sulfonated group is introduced as a reaction product with a compound containing a sulfonated group.
delete Carbon powder; And a metal oxide which is bonded on the surface of the carbon powder and into which a sulfonated group is introduced, which is a reactant with a compound containing a sulfonated group.
(1) preparing a first carbon composite material comprising a metal oxide bound on a surface of a carbon powder; And
(2) reacting the metal oxide with a compound containing a sulfonate group to prepare a second carbon composite material having a sulfonated group introduced into the metal oxide.

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