KR101665025B1 - Electrochemical system by using ligand-free electrocatalyst of organic halides - Google Patents

Abstract

The present invention relates to an electrolysis system for removing halogen compounds, including the following steps: (a) inserting a precursor of an electroactive catalyst including transition metal hydroxide into a basic solution so as to dissolve the precursor of the electroactive catalyst; (b) applying current after inserting the solution acquired from the step (a) into a reactor so as to activate the electroactive catalyst; and (c) inserting the halogen compound into the reactor so as to remove the halogen compound.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrochemical system using an electrocatalyst without ligand for eliminating halogen compounds,

The present invention relates to an electrolytic system utilizing an electrocatalyst without a ligand for removing a halogen compound, and more particularly, to an electrolytic system using an electrocatalyst having no ligand as an electrolytic system ≪ / RTI >

Air pollutants emitted from various sources are classified into various types such as volatile organic compounds (VOCs), odorous substances, and SOx and NOx. The continuous emission of these air pollutants is not limited to direct environmental pollution such as acid rain Desertification of meteorology and grassland and depletion of water resources are causing serious social problems that directly or indirectly threaten the survival of humankind.

In order to treat such pollutants, various methods such as a dry method such as adsorption, thermal incineration, catalytic reaction, a wet method such as absorption, and a biological treatment method have been proposed variously.

Problems of currently used treatment technologies are that high-temperature processes are used to generate large amounts of carbon emissions, secondary pollutants such as dioxins, and a large amount of oxidizing agents and absorbents continuously required, resulting in wastewater and slurry, And waste catalysts such as waste catalysts generate a vicious circle of environmental pollution.

In order to cut off the vicious cycle of environmental pollution and lead the global low carbon green growth, it is necessary to reduce the secondary pollutants such as a large amount of waste oxidizing agent, wastewater, waste catalyst, And carbon emissions should be drastically reduced.

In order to realize this, it is possible to operate with supply of current only at normal temperature and atmospheric pressure without the need of additional supply of chemicals and without generation of wastes and wastewater, (MEO: Mediated Electrochemical Oxidation) process is suitable.

The electrochemical mediated oxidation process is an aqueous process in which an electrocatalyst is oxidized at the anode of an electrolytic cell and the oxidized medium is oxidized and decomposed in the bulk of the electrolyte. This process almost destroys the organic matter, and ultimately converts the carbon and hydrogen in the organic matter into carbon dioxide and water, which is mostly mineralized. At this time, the reduced medium is again used by being oxidized at the surface of the electrode to be regenerated and reacted with the organic material continuously (Korean Patent Publication No. 2006-0105969, Korean Patent Publication No. 2004-0012770, Japanese Patent Laid- Publication No. 1998-500900).

However, in the intermediate oxidation process, the secured electro-scrubbing technique utilizes only the oxidation reaction occurring at the anode, which is the half portion of the electrolytic cell, and the reduction reaction occurring at the cathode at the other half, that is, The process (MER: mediated electrochemical reduction) is not available.

Further, in performing the intermediate reduction process, it may be important to select the intermediate metal that utilizes the reduction reaction of the cathode liquid portion. In general, it is known that a noble metal catalyst such as platinum is used as a metal catalyst for inducing a reduction reaction, or various kinds of coordination compounds such as ligands are prepared and used in the noble metals. (Korean Patent Laid-Open Publication No. 2015-0073614)

However, since the metal catalyst containing the platinum catalyst and / or the ligand is expensive, the cost increases due to the use thereof. Further, the problem of the complexity of the catalyst recovery process may still occur. Further, in order to be applied to the removal of air pollutants such as halogen compounds, the catalyst is difficult to dissolve sufficiently in a basic solution together with a halogen compound. In addition, the catalyst is stably subjected to a mediated reduction reaction (MER) under the basic solution atmosphere It is difficult to do so.

Korean Patent Publication No. 2006-0105969 (October 12, 2006) Korean Patent Publication No. 2004-0012770 (Feb. Japanese Laid-Open Patent Publication No. 1998-500900 (1998.01.27) Korean Patent Publication No. 2015-0073614 (Jul. 2015)

The present invention provides an electrolytic system that utilizes an electroactive catalyst without a ligand to remove halogen compounds by using an intermediate reduction reaction (MER).

According to an aspect of the present invention,

A diaphragm cell including an anode portion, a cathode portion, and a separator separating the anode portion and the cathode portion; An acidic solution, or a basic solution; And a power supply unit, the electrolytic system comprising:

a) introducing and dissolving a precursor of an electroactive catalyst comprising a transition metal hydroxide into the basic solution to prepare a solution containing the electroactive catalyst;

b) activating the electroactive catalyst by injecting the prepared solution of step a) into the cathode chamber of the cathode section, and then applying current by the power supply section; And

c) introducing a halogen compound into the cathode compartment containing the electroactive catalyst of step b), and removing the halogen compound.

In the electrolytic system according to an embodiment of the present invention, the precursor of the electroactive catalyst is not limited but may be a transition metal hydroxide including at least one of cobalt, nickel, silver, manganese, and copper. More specifically, the precursor of the electroactive catalyst includes cobalt to achieve the object of the present invention, but is not limited thereto.

In the electrolytic system according to an embodiment of the present invention, the pH of the basic solution is 13 or more for the purpose of achieving the object of the present invention, but it is not necessarily limited thereto.

In the electrolytic system according to an embodiment of the present invention, the diaphragm cell includes an anode portion, a cathode portion, and a separator controlling the movement of the proton, and the anode portion includes an anode, an anode chamber, and a cathode tab, The cathode portion may include a cathode, a cathode chamber, and a cathode tab.

The separation membrane may have a plate-like shape including a front surface and a rear surface opposite to the front surface, and the front surface of the separation membrane may be opposed to the anode, but is not limited thereto. Further, the anode is made of platinum, and the anode is made of titanium, but is not limited thereto.

In the electrolytic system according to an embodiment of the present invention, the current density in step b) may be 1 to 100 mA / cm ² , but is not limited thereto.

The activation of step b) may be performed by reducing the transition metal ion of the electroactive catalyst by an intermediate reduction reaction, but is not limited thereto. In addition, the change value of the oxygen reduction potential before and after the intermediate reduction reaction may be 100 to 1500 mV, but the present invention is not limited thereto.

In the electrolytic system according to an embodiment of the present invention, the halogen compound may include at least one of allyl chloride and trichlorethylene, but is not limited thereto.

In addition, it is preferable to apply ultrasonic waves to the cathode chamber in the step c).

In the present invention, it is preferable to apply ultrasonic waves to the cathode chamber of the step b), and the solution obtained in the step c) may be introduced into the cathode chamber of the step b). Although this is not a limitation, it is preferable for the continuous removal of the halogen compound according to the present invention.

Further, the present invention can also disclose an oxidation / reduction apparatus, an article used for removing a halogen compound using the electrolytic system described above.

The electrolytic system for removing halogen compounds according to the present invention is economical and improves the rate and the rate of the mediated reduction reaction by using a low-cost transition metal hydroxide electroactive catalyst without using a catalyst containing an expensive ligand.

In addition, the electrolytic system according to the present invention does not require the addition of an electrocatalyst, and the process of removing the halogen compound is continuously operated.

In addition, the present invention provides a device and system using the electrolytic system of the present invention to reduce greenhouse gas emissions by using sustainable green technology capable of overcoming the problems of existing environmental technologies, that is, using clean energy at low temperature and atmospheric pressure No additional supply of oxidizers or chemicals is required, which can provide guidelines for the development of zero emission technology without the emission of secondary pollutants.

1 is a process diagram of an electrolytic system for removing halogen compounds according to embodiments of the present invention,
2 is a schematic diagram showing an apparatus for performing a conventional intermediate oxidation process,
3 is a schematic diagram showing an apparatus for an intermediate reduction reaction according to embodiments of the present invention,
FIG. 4 is a schematic diagram illustrating a diaphragm cell according to embodiments of the present invention,
5 is a photograph showing dissolution characteristics of an electrocatalyst according to an embodiment of the present invention,
6 is a graph showing the oxygen reduction characteristics of the electrocatalyst according to Examples and Comparative Examples of the present invention,
7 is a graph showing redox characteristics of the electrocatalyst according to Examples and Comparative Examples of the present invention,
8 is a graph showing the reduction rates of the electrocatalyst according to Examples and Comparative Examples of the present invention,
9 is a graph showing the reduction characteristics of the electrocatalyst according to Examples and Comparative Examples of the present invention,
10 is a graph showing the removal characteristics of a halogen compound in an electrolytic system according to Example 1 of the present invention,
11 is a graph showing the reduction ratio of an electrolytic system according to embodiments of the present invention and comparative examples,
12 is a graph showing the removal characteristics of a halogen compound in an electrolytic system according to Embodiment 1 of the present invention.

Hereinafter, the electrolytic system for removing halogen compounds of the present invention will be described in detail. The following embodiments and drawings are provided by way of example so that those skilled in the art can fully understand the spirit of the present invention. In addition, unless otherwise defined in the technical and scientific terms used herein, unless otherwise defined, the meaning of what is commonly understood by one of ordinary skill in the art to which this invention belongs is as follows, A description of known functions and configurations that may unnecessarily obscure the gist of the present invention will be omitted. It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. In the present specification, the singular form includes plural forms unless otherwise specified in the specification. It is noted that the terms "comprises" and / or "comprising" used in the specification are intended to be inclusive in a manner similar to the components, steps, operations, and / Or additions. The terms first, second, etc. may be used to describe various elements, but the elements should not be limited by terms. Terms are used only for the purpose of distinguishing one component from another. Hereinafter, the same member numbers are used for the same members in order to facilitate understanding. In the present specification, the term " connected "includes not only a direct connection but also a connection via another member in the middle.

In describing the present invention, the term "diaphragm cell" may refer to an electrochemical cell having a diaphragm or separator provided between an anode and a cathode, and may refer to a two-electrode system including an anode and a cathode.

In describing the present invention, the term " intermediate reduction reaction (MER) "may mean intermolecular electron exchange around the cathode. As a specific example, an intermediate reduction reaction may mean a reaction in which a metal ion of an electrocatalyst receives electrons around a cathode to cause a transition to a low oxidation state.

In describing the present invention, the term "electroactive catalyst" may refer to a substance capable of directly receiving electrons (oxidation or reduction) around the cathode and participating in an electrochemical reaction. Be expressed by the ^{like-specific,} an example non-limiting one, said electroactive catalyst is ^{[M x + (HA)]} y (z) -, [M (x-1) + (HA)] y (z + 1) . Wherein x means a natural number of 1 to 6, y means a natural number of 1 to 10, and z means a natural number of 1 to 10.

In the above formula, M may be a transition metal, M ^{(x-1) +} may be a reduced metal ion or metal, and M ^{(x) +} means an oxidized metal ion . Further, HA means a halogen material.

2, a conventional electrolytic system for removing pollutants includes a diaphragm cell 10 including an anode portion, a cathode portion, and a separator, a power supply portion for supplying power to the diaphragm cell, A cathode tank 60 for supplying an anolyte to the diaphragm cell, and a cathode tank 70 for supplying catholyte to the diaphragm cell.

Referring to the electrolytic system of FIG. 2, the electrolytic system using the diaphragm cell of the present invention differs from the electrolytic system of the prior art in that the prior art is made only by the intermediate oxidation process (MEO). In particular, There is a drawback. In addition, there is a difference in that the electrolytes in the anode and the cathode are used only as an acidic solution.

The present inventor has stably applied the intermediate reduction process (MER) which can stably remove the halogen compound pollutants in the electrolytic system using the diaphragm cell, after the endeavor for many years, An electrocatalyst which can be operated is developed and an electroactive catalyst which is dissolved in the electrolyte and has no ligand which is very stable in a strong base has been developed and the orientation of the separator in the diaphragm cell which maximizes the removal efficiency of the pollutant, Respectively.

An electrolytic system for removing halogen compounds using an intermediate reduction reaction (MER) according to the present invention is characterized in that a) a precursor of an electrocatalyst containing a transition metal hydroxide is added to and dissolved in a basic solution to obtain a solution containing the electrocatalyst Lt; / RTI > b) activating the electroactive catalyst by applying a solution of step a) to the reactor and applying an electric current; And c) introducing a halogen compound into the reactor to remove the halogen compound.

More specifically, the electrolytic system for removing halogen compounds according to the present invention comprises: a diaphragm cell including a cathode portion, a cathode portion, and a separator separating the anode portion and the cathode portion; An acidic solution, or a basic solution; And a power supply unit, comprising: a diaphragm cell including an anode portion, a cathode portion, and a separator separating the anode portion and the cathode portion; An acidic solution, or a basic solution; And a power supply, comprising the steps of: a) injecting and dissolving a precursor of an electroactive catalyst comprising a transition metal hydroxide into a tank containing said basic solution to produce a solution containing said electroactive catalyst ; b) activating the electroactive catalyst by injecting the prepared solution of step a) into the cathode chamber of the cathode section, and then applying current by the power supply section; And c) introducing a halogen compound into the cathode compartment containing the electroactive catalyst of step b), thereby removing the halogen compound.

In addition, the precursor of the electroactive catalyst may be characterized by being ion-bonded to a hydroxyl group, and the reactor is not limited to a large number but may include a diaphragm cell to achieve the object of the present invention. The precursor of the electroactive catalyst can be replaced with an expensive organic ligand-containing complex, an expensive precious metal catalyst, and the like, which is economical.

The pH of the basic solution is preferably 13 or more for increasing the production rate of the electrocatalyst of the present invention. It can be seen that the potential window of the metal ion of the electroactive catalyst of the present invention is greatly expanded to increase the reactivity.

Also, the precursor of the electroactive catalyst is a transition metal hydroxide containing cobalt, which is preferable for the stable intermediate reduction reaction of the present invention and the removal of a halogen compound.

The diaphragm cell includes an anode, a cathode, and a separator for controlling the movement of the proton. The anode includes an anode, an anode chamber, and a cathode tab. The cathode includes a cathode, a cathode, But the present invention is not necessarily limited thereto.

In addition, the separation membrane may have a plate-like shape including a front surface and a rear surface opposite to the front surface, and the front surface of the separation membrane may be opposed to the anode, but is not limited thereto. Further, the anode is made of platinum, and the anode is made of titanium, but is not limited thereto. This is good for increasing the production rate of the electroactive catalyst of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows a process diagram of an electrolytic system for removing halogen compounds according to the present invention. As shown in FIG. 1, the electrolytic system according to the present invention includes a precursor selection step (S10) of an electroactive catalyst, a pH control step (S20) of a reaction medium, a mixing step (S30) of a precursor and a reaction medium, A step S40, a current application step S50, and a pollutant injection and removal step S60.

In the electrolytic system according to an embodiment of the present invention, the step (S10) of selecting the precursor of the electroactive catalyst may be a step of selecting a precursor of the electroactive catalyst containing the transition metal hydroxide. The precursor of the electroactive catalyst may be a stable material in a strong basic solution atmosphere. As a specific example, the precursor of the electroactive catalyst may be a transition metal compound selected from one or more transition metals. As a more specific example, the precursor of the electroactive catalyst may be a transition metal hydroxide comprising at least one of cobalt, nickel, silver, manganese, and copper.

Once the precursor of the electroactive catalyst is selected, the concentration of the selected precursor can then be determined. For example, if the precursor is cobalt hydroxide and the basic solution comprises sodium hydroxide, the cobalt hydroxide may be in the range of 0.1 to 10 mM based on 1 M sodium hydroxide, but is not limited thereto.

The pH controlling step (S20) of the reaction medium may include a step of selecting the type of the reaction medium and controlling the concentration of the reaction medium. The reaction medium may be a basic solution.

In the electrolytic system according to an embodiment of the present invention, the pH of the reaction medium may be 13 or more, but is not limited thereto. For example, when the reaction medium has a pH of 13 or more, the precursor of the electroactive catalyst according to the present invention can be substantially dissolved, and more particularly, to dissolve the precursor including cobalt.

In detail, the reaction medium may be a basic solution selected from at least one of aqueous sodium hydroxide solution, aqueous potassium hydroxide solution, aqueous manganese hydroxide solution and aqueous alkylamine solution. Specifically, the basic solution is preferably an aqueous solution of potassium hydroxide, but the present invention is not limited thereto.

The step (S30) of mixing the precursor and the reaction medium may include dropping the precursor and the reaction medium described above into a container such as a negative electrode tank containing a basic solution and mixing the precursor and the reaction medium. The mixing method may be carried out by a method known to those skilled in the art, and the detailed mixing method may be changed depending on the type and concentration of the precursor and the type and concentration of the reaction medium.

That is, when the precursor of the electrocatalyst is introduced into the reaction medium and mixed by the mixing method described above, the precursor of the electrocatalyst can be dissolved in a short time, and the solution containing the electrocatalyst can do.

Next, the step of injecting (S40) into the reactor may include a step of injecting a solution in which the electroactive catalyst is dissolved into a reactor. The reactor is not particularly limited, but may mean an anode chamber, a cathode chamber, a diaphragm cell, or the like, which will be described later. The above-mentioned method of introduction can be carried out by a method commonly known to those skilled in the art, and a specific example thereof can be supplied at a predetermined flow rate using a peristaltic pump.

In detail, the flow rate is not limited to achieving the object of the present invention, but may be 10 to 500 mL / min, and the solution prepared in step S30 may be independently injected into a reactor such as an anode chamber or a cathode chamber can do. For example, the reaction rate of the electrocatalyst according to the present invention can be improved by selecting the flow rate corresponding to the concentration of the first medium or the second medium depending on the type and concentration of the above-mentioned reaction medium.

Further, the introduced solution may be returned to the flow rate within the above-mentioned range from the anode tank 600 in the anode chamber to the cathode tank 700 in the cathode chamber.

As shown in FIG. 1, the step of applying current (S50) may include a step of applying an electric current to a solution in which the electroactive catalyst injected into the reactor is dissolved. By applying an electric current to the electrocatalyst, the electrocatalyst can be activated.

The activation of the electrocatalyst is not limited to a specific one, but means that the metal ion of the electrocatalyst can be reduced by an intermediate reduction reaction. This can be expressed by the following formula 1, but the metal material of the electroactive catalyst is not limited to cobalt.

[Formula 1]

In the step of applying the current (S50), the applied current density may be 1 to 100 mA / cm ² , preferably 10 to 50 mA / cm ² , more preferably 20 to 40 mA / cm ² Lt; / RTI > The reaction rate, the reaction rate, and the like of the intermediate reduction reaction when operating within the above range.

Also, referring to FIG. 6, the oxygen reduction potential (ORP) of the intermediate reduction reaction is in the range of 100 to 1500 mV , Preferably 150 to 1000 mV, and more preferably 170 to 800 mV. This is good for ensuring the stability and homogeneity of the electrocatalyst of the present invention, but the present invention is not necessarily limited to the above category.

In the present invention, the step of injecting and removing contaminants (S60) may include the step of contacting the electroactive catalyst activated in the step (S50) with a halogen compound to remove the halogen compound.

The halogen compound may be an air pollutant, and may be a substance that can be dissolved in the above-mentioned basic solution. As a specific example, the halogen compound may include an organic chlorine compound. As a more specific example, the organic chlorine compound may be a compound containing at least one of allyl chloride and trichlorethylene, but is not limited thereto.

In addition, the reactor described above includes the activated electroactive catalyst, and the halogen compound can be removed or decomposed by injecting a halogen compound. Further, the halogen compound can be further removed or decomposed by applying an electric current after injecting the halogen compound. The amount of the halogen compound injected may be 1 to 500 ppm per minute, but the present invention is not limited thereto.

As a specific and non-limiting example, the reaction formula in which the halogen compound is removed can be represented by the following formula 2, but the halogen compound is not necessarily limited to allyl chloride.

In the above formula 2, AC may mean allyl chloride.

When an electric current is applied to the reactant after the halogen compound is injected and the reaction proceeds as shown in Formula 2, the oxidized electroactive catalyst can be returned to the activated electroactive catalyst in the initial state. This can be expressed by the following formula 3, but the electrocatalyst is not necessarily limited to cobalt.

In the electrolytic system according to an embodiment of the present invention, the removal efficiency of the halogen compound may be 90% or more. The method for measuring the removal efficiency of the halogen compound is not limited, but can be measured using the HACH analysis method.

In addition, the removal characteristics of the halogen compound can be measured using spectroscopy using infrared rays or the like. As shown in FIG. 12, it can be seen that the peak of allyl chloride including C-Cl stretching vibration and the like is almost removed by the electrolytic system according to the present invention.

Further, in the step of injecting and removing contaminants (S60), ultrasonic waves may be applied to the solution into which the halogen compound is injected. This can improve the rate and reaction rate of removal of the halogen compound according to the above-mentioned formula (2) when the metal ion of the activated electrocatalyst contacts with the halogen compound.

In addition, contaminants may be injected into and removed from the reactor while the current is continuously applied to the reactor in the step of injecting and removing the contaminants (S60), but the present invention is not limited thereto.

In addition, the solution obtained in step (S60) (or after step S60) may be introduced into the reactor (cathode chamber) of step b). This can be reused by activating the metal ions of the oxidized (or deactivated) electroactive catalyst, and the halogen compound removal of the electrolysis system according to the present invention can be continuously performed.

Further, in removing the halogen compound continuously, the ultrasonic wave may be applied while the current of the step b) is applied. This may improve the reaction rate at which the electroactive catalyst is activated and may be effective in preventing electrodeposition of the electrode. In addition, the halogen compound elimination electrolysis system according to the present invention can be further continuously operated.

For example, the ultrasonic wave may have a frequency (20 kHz) higher than that of the audible frequency region, and the frequency of the ultrasonic wave applied in the ultrasonic wave applying process of the present invention may be more than 20 kHz and less than several hundred kHz. In addition, the removal rate of the halogen compound of the present invention can be improved by 10 to 50% by the ultrasonic wave application process.

In the electrolytic system according to an embodiment of the present invention, the precursor of the electroactive catalyst in the above step (S10) may be a transition metal hydroxide containing at least one of cobalt, silver, nickel and copper.

As a specific, non-limiting example, the reduction potential of an electroactive catalyst comprising transition metals is shown in Table 1 below. This can be confirmed when the basic solution is pH 13 or higher, but is not limited thereto.

[Table 1]

For example, the electrocatalyst (or metal compound) containing cobalt may have a better reducing power than the electrocatalyst (or metal compound) containing another metal. , Reduction potential of Co ^{2 +} As shown in Table 1 represents approximately -1.2 V, Ni ^{2 +} are respectively from about -0.8 V, about -0.42 V Cu ^{2 +} is. In addition, SHE can refer to a standard hydrogen electrode.

However, Ag ^{2 +} is a good or a reducing power analogy to the Co ^{2 +,} Co ^{2 +,} compared relatively expensive, and the Ag ⁺ is a transition at the time of intermediate reduction cathode is electro-deposition can result in the electrodes, and (see Table 1), This may lead to electrode deterioration and durability problems in the chemical cell. In addition, it is understood that the metal containing Ni ^{2 +} or Cu ²⁺ has a relatively lower reduction potential than Co ^{2 +} .

Further, in achieving the object of the present invention, the electrocatalyst containing cobalt is very stable because it is stable in a strong base above pH 13, and the intermediate reduction reaction can be reversibly repeated, but is not necessarily limited thereto.

In addition, in the electrolytic system according to the embodiment of the present invention, the precursor of the different electrocatalyst in step a) is added to the acidic solution and the basic solution, respectively, and dissolved, and b) the acidic The basic solution containing the other electroactive catalyst is put into the cathode chamber of the cathode section and then the electric current is applied by the power supply section so that the metal ion of the electroactive catalyst injected into the basic solution flows into the anode chamber of the anode section, May be activated.

Specifically, precursors of the different electroactive catalysts may include cobalt hydroxide containing cobalt, cobalt sulfate, and the like. The cobalt hydroxide may be introduced into the basic solution and injected into the cathode chamber while the cobalt sulfate may be introduced into the acid solution and injected into the anode chamber. At this time, the concentration of the cobalt hydroxide is similar to or the same as that described above, and the concentration of the cobalt sulfate may be 0.5 to 10 mM with respect to 1 M sulfuric acid, but the present invention is not limited thereto.

The present invention may also allow the reaction medium to further comprise an acidic solution, but is not necessarily limited thereto. The acid solution may be an aqueous solution selected from at least one of an aqueous nitric acid solution, an aqueous sulfuric acid solution, and an aqueous methanesulfonic acid solution. Specifically, the acid solution (anolyte solution) is preferably an aqueous sulfuric acid solution, but the present invention is not limited thereto.

When sulfuric acid or an aqueous solution of sodium hydroxide is used as the reaction medium, the concentration may be 1 to 20 M, respectively. However, the concentration is preferably not higher than the concentration of sulfuric acid. For example, the acidic solution may include sulfuric acid and the basic solution may include sodium hydroxide. The molar ratio of sulfuric acid to sodium hydroxide may be 4: 6 to 1: 9, but the present invention is not limited thereto.

Referring to FIG. 5, the dissolution characteristics of the electrocatalyst of step a) according to the present invention may vary depending on the type and concentration of the electrocatalyst, the type and concentration of the reaction medium, the pH, the reaction time, Can be improved.

As a non-limiting and specific example, the precursor of the electroactive catalyst is cobalt hydroxide. When the amount of cobalt hydroxide is in the range of 0.001 to 0.05 M, the dissolution characteristics may vary depending on the concentration of the basic solution, but the present invention is not limited thereto . In addition, the basic solution may contain sodium hydroxide, and the concentration of sodium hydroxide is similar to or similar to that described above.

As shown in FIG. 5A, when the concentration of sodium hydroxide is 6 M or less, the basic solution containing the cobalt hydroxide may exhibit pink color. In addition, a dark precipitate that is not dissolved in the lower part of the basic solution layer showing pink color can be identified. If the concentration of sodium hydroxide is below 6 M, the cobalt hydroxide is not sufficiently dissolved and can be precipitated in the lower part of the basic solution layer. Then, it is introduced into the reactor (cathode chamber) A problem may arise in the activation.

5b), when the concentration of sodium hydroxide is 7 M or more, the basic solution containing the cobalt hydroxide may exhibit a dark blue color. Further, it can be confirmed that the dark blue-colored basic solution does not generate a precipitate. If the concentration of sodium hydroxide is 7 M or more, the cobalt hydroxide is sufficiently dissolved. Therefore, it may be advantageous to activate the electroactive catalyst in the current application step (S50) by charging it into the reactor (cathode chamber).

In addition, the present invention can include a medium reducing device applied to the removal of halogen compounds using the above-described electrolytic system for removing halogen compounds. 3, the intermediate reducing apparatus includes a diaphragm cell 1000, an anode tank 600 communicating with the anode chamber of the diaphragm cell for injecting / discharging an acidic solution, and a cathode chamber of the diaphragm cell, And a cathode tank 700 for injecting / discharging a solution.

The apparatus may further include a power supply unit 500 electrically connected to the diaphragm cell. The current density supplied from the power supply device may be 1 to 200 mA / cm ² , but the present invention is not limited thereto.

The anode tank 600 may be connected to the electrochemical cell, and an inlet pipe and a discharge pipe may be provided to communicate the anode tank 700 and the electrochemical cell. A pump may be attached to the injection tube to control the flow rates of the acidic and basic solutions. In addition, the acidic solution and the basic solution are similar to or similar to the above-mentioned solutions. Thus, the electrolytic system according to the present invention can circulate the solution continuously.

The flow rate of the acidic solution injected from the anode tank 600 may be 10 to 500 ml / min, and the flow rate of the basic solution injected from the cathode tank 700 may be similar to or the same as the flow rate of the acidic solution , But the present invention is not limited thereto.

In addition, the positive electrode tank 600 and the negative electrode tank 700 may have discharge ports through which gas is discharged to the upper end portion independently of each other. The outlet may be operated in a manner of opening and closing due to pressure, which can prevent leakage of sulfuric acid gas and chlorine gas which may occur in the oxidation and reduction reaction, and can minimize the desorption of the active ingredient required for the reaction . The precursor of the medium and the injection port into which the reaction medium is injected may also be provided at the same time.

The positive electrode tank 600 and the negative electrode tank 700 may further include at least one electro-scrubber (not shown) having an outlet at an upper end independently of each other and communicating with the outlet. This configuration is based on the idea that chlorine or the like is discharged together with the gas discharged by the above-described intermediate reduction reaction. For example, by providing the electro-scrubber at the rear end of the cathode tank 700, .

In addition, the electro-scrubber used in the present invention may be a scrubber used in a chemical process. If necessary, the electro-scrubber may be provided with a plurality of scrubbers to sequentially scrub different gases, can do.

In addition, the reactor of step b) according to the present invention may include the diaphragm cell 1000, though not necessarily limited thereto.

4, the diaphragm cell 1000 includes an anode portion 200, a cathode portion 300, and a separator 100 that separates the anode portion and the cathode portion and controls the movement of proton, (100) may have a plate-like shape including a front surface and a rear surface opposite to the front surface.

The type of the separation membrane 100 is not limited to attaining the object of the present invention. However, a material capable of transferring a cation (hydrogen ion) is sufficient, and a material stable in a strong acid and strong base solution is better. As a specific and non-limiting example, the separation membrane 100 may be a Nafion polymer membrane including at least one ionic functional group selected from the group consisting of sulfonate, carboxylate, and phosphate.

In an anode chamber (not shown) of the anode part 200, an acidic solution in which a cobalt metal salt is dissolved may be included, and in the cathode chamber 320 of the cathode part 300, cobalt hydroxide May comprise a dissolved basic solution. In addition, the front surface of the separation membrane 100 may have a positive polarity and a rear surface thereof may have a negative polarity.

At this time, when the front surface of the separation membrane is opposed to the anode 210, the movement of the hydrogen ions (H ⁺ ), H ₃ O ^+, etc. generated in the acid solution to the cathode (or basic solution) may be restricted. The yield of Co ^{1 +} can be increased during the reduction reaction. Specifically, when the front surface of the separation membrane is opposed to the anode, the production rate of Co ^{1 +} can be improved by 10 to 50%, as compared with the case where the separation membrane is not opposed to the anode.

In addition, in the electrolytic system according to the present invention, after the solution of step a) is put into a reactor (cathode chamber), a current is applied to activate metal ions of the electroactive catalyst, and the cathode 310 is made of titanium , And the anode 210 may be made of platinum.

Referring to FIG. 7, in an electrolytic system according to an embodiment of the present invention, the medium reduction characteristics may be varied depending on the type of the cathode 310. In the graph of FIG. 7, each curve may refer to a CV (cyclic voltammogram) graph according to the type of the cathode 310.

7, the shape of the curved line may be changed according to the type of the cathode 310 in the CV graph. The cathode 310 may include at least one of amalgam, silver, and glassy carbon (GCE) electrodes including titanium, mercury and silver. Here, the anode may be platinum.

In a concrete and non-limiting example, when the type of the negative electrode is silver, at least one or more crossing points of the CV graph may occur, and Co (I) or Co (O) may be generated.

In other words, in the case where the cathode 310 is made of silver, it is not necessarily limited, but it can be expressed by a reaction formula of the following formulas 4 and 5.

On the other hand, when the cathode 310 is made of titanium, as shown in the graph of FIG. 8, it can be seen that the intermediate reduction reaction is stable because no crossing occurs, and the current values of the starting point and the ending point are almost the same Therefore, when the cathode 310 according to the present invention includes titanium, the intermediate reduction reaction can be performed reversibly.

Further, in the present invention, Co (I) is ^{1 +} Co, Co (II) is Co ^{2 +,} Co (III) may refer to Co ^{+ 3,} other metal ions may also be applicable to this.

Hereinafter, the present invention will be described in detail with reference to the following examples. However, the present invention is not limited to the following examples.

Example 1

The acid solution was prepared by adding 0.01 M CoSO ₄ to an aqueous solution of 0.2 L of 5 M H ₂ SO ₄ dissolved. The basic solution was prepared by adding 0.01 M of Co (OH) ₂ to an aqueous solution of 0.2 L of 10 M NaOH.

The prepared acid solution was introduced into the anode chamber of the diaphragm cell shown in FIG. 3 or 4, and the basic solution was introduced into the cathode chamber. At this time, the diaphragm cell was a plate-shaped, Pt-coated mesh-type anode, a Ti cathode, and a Nafion® 324 separator. The surface areas of the cathode and anode were 4 cm ² . In addition, the distance between the electrode plates was maintained at 5 mm, and at least two Viton rubber gaskets were provided inside the cells, and the thickness thereof was 2 mm. The separation membrane is plate-shaped and divided into a front surface and a rear surface. The orientation of the separator, that is, the entire surface of the separator, was controlled to face the anode.

The acidic and basic solutions were continuously circulated at a flow rate of 70 ml / min using a peristaltic pump (Masterflex-L / S, Cole Parmer Instrument Company). The current density was applied at 30 mA / cm ² using a power supply (Korea Switching Instruments), and the activated metal ion, Co (I), was generated.

The production rate of the activated metal ion, Co (I) ion, depends on the type and concentration of the base. The pH of the acid or base was measured using a pH / ISE analyzer (iSTEK, pH-240L, USA) using the analyzer and an ORP The concentration was calculated. At this time, the standard electrode was a 6 mm Pt electrode containing Ag / AgCl, and 0.1 M KMnO ₄ was used as the titration electrode. As a result of pH measurement, the pH of the basic solution was 13.5. The redox potential measured therefrom is shown in Fig. 6 (d).

Further, the generation rate of the Co ^{1 +} (or intermediate reaction rate of reduction) was calculated according to the following equation 1.

In the above formula (1), C means the concentration of hydroxide containing cobalt. In addition, in the formula 1 [Co (I) (OH ) 4] The concentration of ³ was measured by monitoring the concentration of KMnO _4, the concentration of [Co (II) (OH) 4] 2- is the initial Co (OH) ₂ was used.

Then, 3800 ppm of allyl chloride (AC) was injected into the basic solution in which 12% of Co (I) was produced, thereby confirming the removal characteristics of the allyl chloride. 3 mL of the allyl chloride-removing solution was neutralized with perchloric acid and centrifuged. Finally, 1 M NaOH was added to the solution to adjust the pH to 6 to 7. After 0.8 mL of mercury thiocyanate (HACH solution) was added thereto, 1 M of perchlorate was added to measure the chlorine content Was prepared. At this time, the measurement of the chlorine content was performed using a HACH non-dyeing machine (DR-2800, USA).

The removal characteristics of allyl chloride using the colorimeter are shown in Table 2 below.

[Table 2]

In Table 2, the removal efficiency is expressed as a percentage by calculating the theoretical concentration of chlorine in the added allyl chloride and the chlorine concentration measured using the HACH colorimeter after the reaction. Also, in Table 2, # indicates a value that can not be measured beyond the HACH analysis range. It can be seen that the removal efficiency is at least 93%. 10, the slope of the allyl chloride before injection (before about 40 minutes) and the slope after injection (after about 40 minutes) are largely different. Therefore, even if the time after injection exceeds 20 minutes (see Table 2) It can be predicted that the removal of allyl proceeds. Thus, the removal efficiency can be expected to be almost 100%.

In addition, the removal characteristics of the allyl chloride were confirmed by the infrared absorption spectrum shown in Fig. The spectrum was measured in liquid phase using FTIR (Nicolet-Is10 spectrometer, Thermo scientific Nicolet-iS). 12 (a) is an FTIR analysis graph of a basic solution before injection of allyl chloride, and FIG. 12 (b) is a graph showing the FTIR of the reacted solution after 30 minutes by injection of 3800 pm of allyl chloride, Analysis graph. About 715 cm, as illustrated by the broken line in FIG. 12 ^- got the peak shown in Figure ^1, about 1740 cm ^-1, around 2350 cm ^-1, a peak appeared at about 715 cm ^-1 is the stretching vibration of the C-Cl allyl chloride , And it was confirmed that the allyl chloride was removed as the intensity of the peak decreased (or abolished). Also, the peak at about 1740 cm ^-1 is due to the stretching vibration of C = O, and the peak at about 2350 cm ^-1 is due to the stretching vibration of OH. As the intensity of the two peaks increases, the allyl chloride is removed and a stable by-product is produced.

Comparative Example 1

The same procedure as in Example 1 was carried out except that the negative electrode was made of Ag.

Comparative Example 2

The procedure of Example 1 was repeated except that the cathode was made of glassy carbon.

Comparative Example 3

The same procedure as in Example 1 was carried out except that the negative electrode was made of Hg-Ag amalgam.

Referring to FIG. 6, FIG. 6A is a graph showing the redox potential of Comparative Example 1, FIG. 6B is a graph showing the redox potential of Comparative Example 2, and FIG. A graph showing the redox potential of Comparative Example 3. Fig. 6 (d) is a graph showing the redox potential of Example 1. Fig.

Referring to FIG. 7, FIG. 7 is a graph showing redox characteristics of the electroactive catalyst according to Example 1 and Comparative Examples 1 to 3. The reduction peak of the electrocatalyst according to Example 1 appeared at about -0.71 V and the oxidation peak appeared at about -0.44 V with a reverse scan and no crossing occurred. The reduction peak of the electrocatalyst according to Comparative Example 1 appeared at about -0.71 V, and the oxidation peak showed about -0.49 V at the inversion. The crossing points according to Comparative Example 1 were about -0.7 V, -0.6 V, and -0.4 V, respectively. The reduction peak of the electrocatalyst according to Comparative Example 2 appeared at about -0.7 V, and the oxidation peak at about 0.49 V when inverted. The crossing points according to Comparative Example 2 were about -0.9 V and 0.65 V, respectively. The reduction peak according to Comparative Example 3 appeared at about -1.12 V and the oxidation peak at -0.29 V and -0.18 V, respectively. Unlike the other examples, in Comparative Example 3, it was confirmed that the current values of the start point and the end point do not coincide with each other.

Referring to FIG. 8, FIG. 8 is a graph showing the reduction rates of the electrocatalyst according to Example 1 and Comparative Examples 1 to 3. The reduction rate refers to the production rate of Co (I) in Formula 6. As shown in FIG. 8, the maximum reduction ratio according to Example 1 was found to be about 10 times higher than the maximum reduction ratio according to Comparative Example 2. This property is effective for improving the removal rate of allyl chloride.

Referring to FIG. 9, FIG. 9 is a graph showing current characteristics of the electrocatalyst according to Example 1 and Comparative Examples 1 to 3. It can be seen that the current characteristics exhibit different slopes depending on the scanning speed of the potential. In Example 1 according to the linear fitting, the slope was about 1, the slope of Comparative Example 1 was about 5, the slope of Comparative Example 2 was about 0.2, and that of Comparative Example 3 was about 2. [

Referring to FIG. 10, there is shown a graph showing allyl chloride removal characteristics of the electrolytic system according to Example 1 of the present invention. FIG. 10 (a) shows the production rate of Co (I) with time, and FIG. 10 (b) shows the redox potential of the present invention with time. As shown in FIG. 10, it can be seen that the production rate and redox potential of Co (I) reached a maximum at about 40 minutes, and then rapidly decreased. This is a phenomenon in which allyl chloride is injected about 40 minutes before and can be understood by the reaction formula of the above-described formula (2).

Example 2

The same procedure as in Example 1 was carried out except that the current density was 10 mA / cm ² .

Example 3

And the current density was 50 mA / cm < ^{2 &} gt ;.

Referring to FIG. 11, FIG. 11 is a graph showing reduction ratios of electrocatalysts according to Examples 1 to 3. The reduction rate means the production rate of Co (I), and shows a curve having a different shape according to time. It can be seen that the maximum reduction ratio according to Example 1 is increased about 5 times as compared with Example 2. [

With the above-described characteristics, it was confirmed that the electrolysis system of the present invention was maximized in the removal of allyl chloride.

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 embodiments, but, on the contrary, Those skilled in the art will recognize that many modifications and variations are possible in light of the above teachings.

Accordingly, the spirit of the present invention should not be construed as being limited to the embodiments described, and all of the equivalents or equivalents of the claims, as well as the following claims, belong to the scope of the present invention .

100: membrane
200: anode part, 210: anode,
300: negative electrode portion, 310: negative electrode, 320: negative electrode chamber (reactor)
410, 420: case, 411, 412: inlet port, 421, 422:
500: Power supply
600: positive electrode tank,
700: cathode tank, 710: cathode tank inlet, 711: pollutant inlet port, 720: cathode tank outlet

Claims (13)

A diaphragm cell including an anode portion, a cathode portion, and a separator separating the anode portion and the cathode portion; An acidic solution, or a basic solution; And a power supply unit, the method comprising:
a) introducing and dissolving a precursor of an electroactive catalyst comprising a transition metal hydroxide into the basic solution to prepare a solution containing the electroactive catalyst;
b) activating the electroactive catalyst by a mediated reduction reaction by applying the solution prepared in step a) to the cathode chamber of the cathode section and then applying current by the power supply section; And
c) adding a halogen compound to the cathode compartment containing the electroactive catalyst of step b), and removing the halogen compound.
The method according to claim 1,
Wherein the pH of the basic solution is 13 or more.
The method according to claim 1,
Wherein the precursor of the electroactive catalyst is a transition metal hydroxide containing at least one of cobalt, nickel, silver, manganese, and copper.
The method according to claim 1,
Wherein the precursor of the electroactive catalyst is a transition metal hydroxide comprising cobalt.
The method according to claim 1,
Wherein the anode portion includes a cathode, an anode chamber, and a cathode tab,
The cathode section includes a cathode, a cathode chamber, and a cathode tab,
Wherein the separation membrane has a plate-like shape including a front surface and a rear surface opposite to the front surface,
And the front surface of the separation membrane is opposed to the anode.
6. The method of claim 5,
Wherein the anode is platinum, and the cathode is titanium.
The method according to claim 1,
Wherein the current density in the step b) is 1 to 100 mA / cm < ² >.
The method according to claim 1,
Wherein the activation of step (b) is a reduction of the transition metal ion of the electroactive catalyst.
9. The method of claim 8,
Wherein the change value of the oxygen reduction potential before and after the intermediate reduction reaction is 100 to 1500 mV.
The method according to claim 1,
And in the step c), ultrasonic waves are applied to the cathode chamber.
The method according to claim 1,
Wherein the halogen compound comprises at least one of allyl chloride and trichlorethylene.
12. A compound according to any one of claims 1 to 11,
Wherein ultrasonic waves are applied to the cathode chamber of the step b)
Wherein the solution obtained in step c) is introduced into the cathode chamber of step b).
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