KR101637539B1 - Flow-electrode device by cross flow and capacitive deionization device using this - Google Patents

Abstract

The present invention relates to a flow electrode device using a cross flow of a flow electrode and a capacitive desalination device using the same, and more particularly, Thereby making it possible to reuse the charged flow electrode and to increase the desalination efficiency by utilizing charge neutrality of the desorbed ions in the flow electrode device.
Therefore, it is possible to reduce the amount of the flow electrode consumed for the same time in the operations such as water purification, wastewater treatment, desalination and the like through the electrolytic desalination process according to the present invention, and to increase the desalination performance.

Description

TECHNICAL FIELD The present invention relates to a flow electrode device using a cross flow and a capacitive de-ionization device using the flow electrode device,

The present invention relates to a flow electrode device using a cross-flow and a capacitive desalination device using the flow electrode, and more particularly, to a flow electrode device using cross-flow and more particularly to a flow device using ion exchange phenomenon in a unit cell of a flow electrode filled with a cation and a flow electrode filled with an anion A method of recycling an electrode, and a storage type desalination apparatus using a flow electrode having enhanced desalination efficiency through the method.

Recently, researches on flow electrodes under the name of electrochemical flow capacitors (EFC) have been attracting attention for the purpose of mass storage of energy in the field of energy storage.

In the field of water treatment such as water treatment or wastewater treatment and seawater desalination, an electrochemical process capable of water treatment at a very low energy cost compared to the conventional evaporation method or reverse osmosis (RO) method, namely, a capacitive deionization (CDI) Recently, a flow electrode capacitive deionization (FCDI) process using a flow electrode, a new technology that facilitates continuous process and large capacity, is under development.

The EFC is a concept in which ions move and store between the flow electrodes disposed on both sides of the separator by an external power source and stores energy through the electrode. The ions of the saline water between the separators are moved to both flow electrodes by an external power source It has a similar concept to FCDI which is desalted.

In particular, since FCDI can store energy by storing adsorbed ions in a separate container, it is evaluated as a technology applicable not only to desalination but also to an energy storage field.

In view of the above characteristics, the present inventors have filed for a flow electrode device (Korean Patent No. 10-1233295), and have developed it (Korean Patent No. 10-1318331), Energy Storage (Korean Patent No. 10-1210525) (Korean Patent No. 10-1221562).

In the desalination method using the flow electrode device, it is necessary to discharge the flow electrode in which ions are saturated, and the amount of the flow electrode is increased in order to increase the salt water treatment capacity.

Korean Patent No. 10-1233295 Korean Patent No. 10-1318331 Korean Patent No. 10-1210525 Korean Patent No. 10-1221562

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for reusing a charged flow electrode by using a characteristic of an ion exchange membrane selectively passing only positive ions or anions and an efficient and economical desalination process .

As a result, the amount of the electrode used can be reduced simply by exchanging the ions adsorbed on the flow electrode generated in the unit cell, and the desorption efficiency can be increased by utilizing the charge neutrality of the desorbed ions in the flow electrode device.

According to an aspect of the present invention, there is provided an electrolytic cell including: a flow cathode flow channel and a flow cathode flow channel through which a flow electrode having a flowing electrode active material flows; and an electrolyte flow channel through which an electrolyte flowing between the flow anode flow channel and the flow cathode flow channel flows An anode is movable between the electrolyte and the flow cathode, and a cation is movable between the electrolyte and the flow cathode, and a flow electrode passing through one of the flow cathode flow path and the flow cathode flow path is introduced . The flow-through electrode device according to claim 1,

In the present invention, the flow electrode is defined as the sum of the flow anode and the flow cathode. The flow electrode is a mixture of an electrode active material and a fluid. It is possible to use a water-soluble electrolyte or an organic electrolyte as the fluid used for the flow electrode. Particularly, it is possible to use fresh water or brine as the fluid. Also, the flow electrode through which the positive ions are adsorbed by passing through the flow cathode flow path is a flow cathode, and the flow electrode through which the anion is adsorbed through the flow anode flow path is a flow anode.

The flow electrode passing through the flow anode flow path is supplied to the flow cathode flow path, and the flow electrode passing through the flow cathode flow path is supplied to the flow anode flow path. At this time, the desalination performance of the flow electrode device can be enhanced by attracting the counter ions from the electrolyte flow channel by the ion charge which is desorbed from the electrode active material and flows along with the flow electrode flow channel.

Further, a flow electrode having a charge is supplied to at least one of the flow cathode flow path and the flow cathode flow path.

According to another aspect of the present invention, there is provided a method of manufacturing an electrolytic cell including the flow electrode device, a flow electrode supply part supplying the flow electrode to the flow electrode device, an electrolyte supply part supplying the electrolyte to the electrolyte flow path, And a power supply for supplying electric power to the flow electrode device. In addition, an electrode regeneration controller for measuring and collecting the saline concentration of the flow electrode; A fluid-liquid separator for separating and discharging the concentrated fluid from the separated flow electrodes; And an electrode regeneration unit for regenerating the flow electrode regenerated by the flow electrode supply unit or the flow electrode device by adding a fluid having a concentration lower than a reference concentration to the flow electrode from which the fluid is separated.

And a part or all of the flow electrode is replaced with a flow electrode having a relatively lower concentration than a flow electrode flowing through the flow electrode device, when the salt concentration of the flow electrode is a predetermined concentration or more.

It is also possible that a part or the whole of the flow electrode is replaced with a flow electrode having a relatively lower concentration than the flow electrode flowing in the flow electrode device at predetermined time intervals.

The flow electrode supply unit may further include a first flow electrode supply unit for collecting flow electrodes from the flow anolyte channels and supplying the flow electrodes to the flow cathode flow path, a second flow electrode supply unit for collecting flow electrodes from the flow cathode flow path, And a flow electrode supply unit.

The flow anode in which the anion is adsorbed by the desalination process and the flow cathode which has adsorbed the cations are supplied to the opposite electrode flow path to desorb the adsorbed ions to release the electrode fluid. As a result, in addition to the adsorption capacity of the electrode active material, counter ions as much as the amount of released ions are introduced from the electrolyte flow path, thereby enabling high-efficiency continuous desalination operation.

Also, it is possible to regenerate the flow electrode simply by separating the concentrated electrolyte from the flow electrode and replacing it with a fresh electrolyte.

Through the present invention, it is possible to increase desalination performance by ion exchange phenomenon of the flow electrode generated in the flow electrode flow path, and to simultaneously carry out the adsorption and regeneration of the adsorption capacity in the unit cell, so that the flow electrode can be used continuously several times Do.

Therefore, it is possible to drastically reduce the amount of flow electrodes consumed for the same time in operations such as water purification, wastewater treatment, desalination and the like through the storage and desalination process according to the present invention and to integrate supply and storage of flow anode and flow cathode The installation space can be greatly reduced and the desalination performance can be greatly increased.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of a charge and discharge apparatus using a flow electrode device according to Embodiment 1 of the present invention; FIG.
FIG. 2 is a graph of current change over time in Example 1 and Comparative Example of the present invention. FIG.
3 is a schematic view of a charge and discharge apparatus using a flow electrode device according to a second embodiment of the present invention.
4 is a schematic view of a charge and discharge apparatus using a flow electrode device according to a third embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. In the drawings, the same reference numerals are used to designate the same or similar components, and the same reference numerals will be used to designate the same or similar components. Detailed descriptions of known functions and configurations are omitted.

First, a flow electrode device 106 commonly used in all embodiments of the present invention will be described.

 1, the space defined between the anode current collector 111 and the cathode current collector 120 is partitioned by the anode separator 115 and the cathode separator 117, do. That is, the flow electrode device 106 includes a flow cathode flow path 114 between the anode separator 115 and the anode current collector 111, a flow between the cathode current collector 120 and the anode separator 117, An anode flow path 119 and an electrolyte flow path 116 between the cathode separation membrane 115 and the anode separation membrane 117.

A flow electrode flows through the flow cathode flow path (114) and the flow anode flow path (119). The flow cathode 112 is a state in which a flow electrode in the form of a dispersed slurry in which an electrode active material is mixed with a fluid flows through the flow cathode passage 114 while the cation is adsorbed, And the anion is adsorbed while passing through the anode flow path 119. Examples of the electrode active material used for the flow electrode include porous carbon (activated carbon, carbon fiber, carbon aerogels, carbon nanotubes, etc.), graphite powder, metal oxide powder and the like.

The fluid may be a solution of a water-soluble electrolyte such as NaCl, H ₂ SO ₄ , HCl, NaOH, KOH and Na ₂ NO ₃ and a solvent such as propylene carbonate (PC), diethyl carbonate (DEC) And an organic electrolytic solution such as tetrahydrofuran (THF). Particularly, it is possible to use brine containing a large amount of salt (particularly, NaCl) or fresh water containing a small amount of salt as the fluid.

It is possible to use a cation exchange membrane which prevents the electrolyte liquid from flowing between the flow cathode and the electrolyte channel and allows only the cation to pass therethrough.

The anode separator 117 may be an anion exchange membrane that prevents the electrolyte liquid from flowing between the flow cathode and the electrolyte channel and allows only the negative ions to pass therethrough.

The electrolyte flows into the electrolyte flow path 116. The electrolyte includes a water soluble electrolyte solution such as NaCl, H ₂ SO ₄ , HCl, NaOH, KOH and Na ₂ NO ₃ and a solution of propylene carbonate Carbonate, PC), Diethyl Carbonate (DEC), and Tetrahydrofuran (THF). Particularly, it is possible to use brine containing a large amount of salt (particularly, NaCl) or fresh water containing a small amount of salt as the fluid. The electrolyte flow path 116 may be formed with a spacer which can form a flow path.

The flow direction of the electrolyte in the electrolyte flow path 116 and the flow direction of the flow in the flow path 114 and the flow path 118 may be the same or opposite to each other.

The electrode current collectors 111 and 120 and the ion-removing membranes 115 and 117 may be any of those used in conventional fluidized bed electrode systems (batteries, batteries, etc.) And can be appropriately selected depending on the purpose and condition of use.

Next, a description will be given of the electrothermal desalination apparatus 100 using the flow electrode device 106. FIG.

In Fig. 2, reference numeral 100 designates a storage and desalination apparatus according to Embodiment 1 of the present invention.

The condensate desalination apparatus 100 mainly comprises a flow electrode device 106 and a flow cathode device for supplying a flow electrode to the flow cathode flow path 114 of the flow electrode device 106, A first flow electrode supply part 141 for collecting a flow anode filled with negative ions from the flow electrode device 119 and a second flow electrode supply part 141 for supplying flow electrodes to the flow anodic flow path 119 of the flow electrode device 106, A second flow electrode supply portion 142 for collecting a flow cathode filled with positive ions from the flow cathode passage 114 and an electrolyte supply portion 144 for supplying an electrolyte to the flow electrode device 106.

A power supply device 130 for supplying current is connected to the flow electrode device 106 so that a potential difference is generated between the anode current collector 111 of the current flow electrode device 106 and the cathode current collector 120 .

Therefore, when the electrolyte and the flow electrode are supplied to the flow electrode device 106, the positive ions are supplied to the electrode active material 111 through the negative electrode separator 115 by the potential applied to the negative electrode current collector 111 and the positive electrode current collector 120, And the negative ions are adsorbed to the electrode active material via the positive electrode separator 117. As a result, the electrolyte having passed through the electrolytic flow path 116 has a low ion concentration, so that fresh water can be obtained or utilized for other purposes.

Then, the flow cathode 112, which has adsorbed the cation through the desalination process and filled with the adsorption capacity, flows into the second flow electrode supply unit 142 and is supplied to the flow cathode flow path 119, adsorbs anions, Flows into the first flow electrode supply part 141 and is supplied to the flow cathode flow path 114 so as to have a single closed loop structure as a whole.

Therefore, the flow cathode 112 re-introduced into the flow electrode device 106 desorbs the cation from the flow channel 119 and re-adsorbs the anion, and the desorbed cation adsorbs the corresponding anion from the electrolyte And the flow anode 119 re-introduced into the flow electrode device 106 desorbs the anions and re-adsorbs the cations from the flow cathode flow path 114, and the desorbed anions Anions are introduced from the electrolyte and concentrated in the electrode fluid.

Therefore, the flow electrode can maintain the adsorption capacity through the above-described process, and can exceed the existing desalination performance.

In addition, the desalination process can obtain the flow anode and the flow cathode filled with the concentrated electrolyte in the flow cathode, and the concentrated electrolyte can be discharged to the sea or used for other purposes. It is possible to use it for the purpose of recovery.

FIG. 3 shows a charge / discharge apparatus 101 according to Embodiment 2 of the present invention.

The flow electrode device 106 of the second embodiment is the same as the flow electrode device of the first embodiment. In the first embodiment, the first flow electrode supply unit 141 and the second flow electrode supply unit 142 are integrated into the flow electrode supply unit 140 to simplify the closed-loop structure of the flow electrode.

Fig. 4 shows a storage and desalination apparatus 102 according to Embodiment 3 of the present invention.

When the desalting process is continued in Example 1, the ion concentration in the flow electrode fluid becomes excessively high, and the desalination performance may decrease. To prevent this, the flow electrode has to be replaced at regular intervals. In addition, the same problem also occurs in the second embodiment, and in order to reuse the flow electrodes for the purpose of energy recovery, there is a disadvantage that one more flow electrode apparatus whose flow direction is opposite to the flow direction is required. The storage and desorption apparatus 102 of the third embodiment can overcome this disadvantage.

That is, when the concentration of the fluid in the flow electrode recovered in the first flow electrode supply part 141 and the second flow electrode supply part 142 exceeds a predetermined concentration, the first flow electrode supply part 141 and the A predetermined amount of flow electrodes can be sent from the second flow electrode supply unit 142 to the fluid-liquid separating unit 143 to separate and discharge the concentrated fluid. To this end, a flow electrode regeneration control unit 150 is required which is capable of supplying a flow cathode and a flow anode to an aliquot and a fluid-liquid separator 143 according to the concentration of the fluid in the flow cathodes and the flow cathodes. The time control or the flow liquid concentration control can be performed for this control.

In addition, the flow electrode from which the concentrated liquid is removed from the fluid-liquid separating unit 143 is supplied to the first flow-electrode regeneration unit 145 and the second flow-electrode regeneration unit 146 through the addition of a new fluid, And supplied to the first flow electrode supply unit 141 and the second flow electrode supply unit 142, respectively, and can be returned to the flow electrode device 105. In addition, the first flow electrode regeneration unit 145 and the second flow electrode regeneration unit 146 may be integrated into one flow electrode regeneration unit.

Therefore, the storage and desalination apparatus 102 can continuously and efficiently perform a desalination process while minimizing the amount of consumed flow electrodes.

Hereinafter, the present invention will be described in more detail with reference to experimental examples. However, the following experimental examples are intended to further illustrate the present invention and should not be construed to limit the scope of the present invention.

[Experimental Example 1]

A cation exchange membrane (Neosepta CMX, Tokuyama, Japan) and an anion exchange membrane (anion exchange membrane) were sandwiched between a rectangular positive electrode and a negative electrode current collector having a fine channel structure (Graphite, 294 x 210 mm, effective area of 228 cm 2) Neosepta AMX, Tokuyama, Japan) and a spacer (Polyester, 0.4 mm).

(ISA-N-10, Ilshin Autoclave, Korea) with a specific surface area of about 3,263 m < 2 > / g and an average pore diameter of 21 ANGSTROM and a total pore volume of 1.71 cc / g were mixed in a 0.1 M NaCl fluid (electrolyte) And pulverized to prepare a flow electrode having an average particle size of 8 mu m of activated carbon in the fluid. The prepared flow electrode was supplied with 0.4 L of the flow electrode to the flow cathode flow path of the flow electrode device at a flow rate of 25 ml / min, and 0.4 L was supplied to the second flow electrode supply portion, The flow of the device was fed into the anode flow path.

The flow electrode passing through the flow cathode flow path was supplied to the second flow electrode supply unit and was supplied again to the flow anode flow path. The flow electrode passing through the flow anode flow path was supplied to the first flow electrode supply unit and supplied again to the flow cathode flow path. Therefore, finally, the whole flow electrode was closed as shown in Fig.

At the same time, the NaCl electrolyte liquid having an electrical conductivity of 53.5 mS / cm was passed through the electrolyte flow path of the flow electrode device at a flow rate of 3 ml / min using a micro metering pump (Minichemi pump) The external terminal of the electrode device was connected to Potentiostat (Ivium Technologies BV, Netherlands), and a desalination experiment was performed by applying a voltage of 1.2V.

The current flowing through the unit cell during the desalination process is shown in FIG.

For comparison, the desalination experiments in the open cycle flow of the flow electrode, which was taken in the existing process, were carried out under the same conditions as described above. The results of the entire experiment are summarized in Table 1 below.

Concentration of input water
(mS / cm) Production number concentration
(mS / cm) Desalination rate
(%) Measuring current
(㎃) Example 53.5 7.32 86.0 2500 Comparative Example 52.2 26.0 50.2 1578

As shown in FIG. 2, unlike the flow of the conventional open cycle, which is a general operating method of the electrolytic desalination apparatus using the flow electrode, the current flowing in the unit cell does not maintain a constant value after the initial decrease, Can be seen. This is because the ions desorbed by the ion exchange occurring in the flow electrode in the unit cell are clogged by the ion exchange membrane and can not flow into the electrolyte channel, and the counter ions are drawn from the electrolyte channel in order to maintain a stable state in the flow channel. Therefore, the current increases until the adsorption capacity of the electrode active material contained in the 0.4 L flow electrode is utilized.

It can be seen that the flatness of the current variation is between 2000 and 3000 seconds, and the desalination performance of the present system is the maximum at this interval. At this time, as shown in Table 1, the current flowing through the flow electrode device was 1.6 times higher than that of the comparative example and 1.7 times higher than that of the comparative example.

The decrease of the current gradually after 3000 seconds is because the salt concentration in the flow electrode fluid exceeds the limit concentration. In order to maintain the performance, a certain amount of salt should be removed in the same manner as shown in FIG.

In addition, 2.5 L of flow electrode is consumed in the operation method of the conventional flow electrode up to 3000 seconds in which the current starts to slowly decrease. However, in this embodiment, only 0.8 L is used, .

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. It can be understood that

100,101,102: Capacitive desalination device 106: Flow electrode device
111: cathode current collector 112: flow cathode
114: flow cathode flow path 115: cathode separator
116: electrolyte flow path 117: anode separator
118: flow anode 119: flow anode channel
120: positive electrode current collector 130: power supply unit
140: flow electrode supply unit 141: first flow electrode supply unit
142: second flow electrode supply unit 143: fluid-liquid separation unit
144: Fluid liquid supply unit 145: First flow electrode regeneration unit
145: second flow electrode regeneration unit 150: electrode regeneration control unit

Claims (8)

A flow cathode flow path and a flow cathode flow path through which a flow electrode having a flowing electrode active material flows and an electrolyte flow path through which an electrolyte flowing between the flow anode flow path and the flow cathode flow path moves,
An anion can move between the electrolyte and the flow anode, and a cation can move between the electrolyte and the flow cathode,
And the flow electrode passing through one of the flow cathode flow path and the flow cathode flow path is introduced into the other flow path.
The flow-through electrode device according to claim 1, wherein a flow electrode passing through the flow cathode flow path is supplied to the flow cathode flow path, and a flow electrode passing through the flow cathode flow path is supplied to the flow anode flow path.
The method according to claim 1,
And a flow electrode having a charge is supplied to at least one of the flow anode flow path and the flow cathode flow path.
A flow electrode device according to any one of claims 1 to 3;
A flow electrode supply unit supplying the flow electrode to the flow electrode device;
An electrolyte supply unit for supplying the electrolyte to the electrolyte flow channel;
And a power supply for supplying power to the flow electrode device.
5. The method of claim 4,
Wherein a part or the whole of the flow electrode is replaced with a flow electrode having a relatively lower concentration than a flow electrode flowing through the flow electrode device when the salt concentration of the flow electrode is not less than a predetermined concentration.
The method of claim 4, wherein
Wherein part or all of the flow electrode is replaced with a flow electrode having a relatively lower concentration than the flow electrode flowing in the flow electrode device at predetermined time intervals.
5. The method of claim 4,
The flow electrode supply unit includes a first flow electrode supply unit that collects flow electrodes from the flow anolyte flow path and supplies the flow electrode to the flow cathode flow path, a second flow electrode supply unit that collects flow electrodes from the flow anolyte flow path, And a supply unit.
A flow electrode device according to any one of claims 1 to 3;
A flow electrode supply unit supplying the flow electrode to the flow electrode device;
An electrolyte supply unit for supplying the electrolyte to the electrolyte flow channel;
A power supply for supplying power to the flow electrode device;
An electrode regeneration controller for measuring and collecting the saline concentration of the flow electrode;
A fluid-liquid separator for separating and discharging the concentrated fluid from the separated flow electrodes; And
And an electrode regeneration unit for regenerating the flow electrode regenerated by the flow electrode supply unit or the flow electrode device by adding a fluid having a concentration equal to or lower than a reference concentration to the flow electrode from which the fluid is separated.

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