Flow electrode capacitive deionization apparatus and flow electrode capacitive deionization method

Abstract

Disclosed are a flow electrode capacitive deionization apparatus and a flow electrode capacitive deionization method. The disclosed flow electrode capacitive deionization apparatus comprises: an electrolyte flow channel; a cation exchange membrane and an anion exchange membrane which define the electrolyte flow channel and are disposed parallel to and spaced apart from each other; a flow cathode channel, serving as a flow path for a flow cathode, disposed parallel to and spaced apart from the electrolyte flow channel with the cation exchange membrane interposed therebetween; a flow anode channel, serving as a flow path for a flow anode, disposed parallel to and spaced apart from the electrolyte flow channel with the anion exchange membrane interposed therebetween; a cathode current collector which defines the flow cathode channel together with the cation exchange membrane and is disposed parallel to and spaced apart from the cation exchange membrane; an anode current collector which defines the flow anode channel together with the anion exchange membrane and is disposed parallel to and spaced apart from the anion exchange membrane; a power supply unit configured to apply a potential difference between the cathode current collector and the anode current collector; and a gas supply unit configured to supply gas to the flow cathode channel and the flow anode channel.

Description

Flow electrode capacitive desalination device and flow electrode capacitive desalination method

[0001] A flow electrode capacitive desalination device and a flow electrode capacitive desalination method are disclosed. More specifically, a flow electrode capacitive desalination device and a flow electrode capacitive desalination method capable of preventing accumulation of flow electrodes within a flow electrode path during operation are disclosed.

[0002] Traditionally, ion exchange resin processes have been widely used for the removal of ionic substances due to their economic and efficient nature. However, these ion exchange resin processes use large amounts of acids and bases during the regeneration process of desalinated ion exchange resins, which additionally generates high-concentration salt wastewater. To overcome these shortcomings, membrane technologies such as reverse osmosis and electrodialysis are widely applied. However, membrane-based processes require periodic membrane replacement, can degrade treated water quality due to membrane fouling, and consume excessive energy during operation.

[0003] Capacitive deionization (CDI) is a new desalination technology that utilizes electrochemical methods. Capacitive deionization utilizes low-voltage electrical energy (1-2 V). When a potential difference is applied between the cathode and anode, ions are adsorbed by electrostatic attraction in the electric double layer formed at the electrode interface. However, since the porous electrodes coated on the current collector are fixed in position, the ion adsorption capacity is limited, requiring periodic regeneration of the porous electrodes. Regeneration of the porous electrodes requires repeated charging and discharging, limiting their ability to be used continuously.

[0004] To overcome the drawbacks of repetitive charging and discharging of this capacitive deionization process and to implement a continuous process, flow-electrode capacitive deionization (FCDI) technology was developed.

[0005] Korean Patent No. 10-1233295 discloses a fluidized bed electrode system, a large-capacity energy storage system, and a water treatment method using the same, which store large amounts of electrical energy while simultaneously and continuously flowing slurry-like electrode materials and electrolytes within a microchannel structure formed on the electrode. The patent overcomes the disadvantage of the existing capacitive deionization (CDI) process of using active materials fixed to a current collector as electrodes, and by continuously operating the microelectrode active materials in a slurry state mixed with the electrolyte, large-capacity can be easily achieved with unit cells having microchannels without the need for large-area electrodes or stacking for large-capacity expansion.

[0006] Korean Patent No. 10-1282794 provides a scale-up technology for a flow-electrode capacitive desalination device. The patent features a modularized flow-electrode capacitive desalination device composed of stacked unit cells.

[0007] When applying the technologies presented above to actual ion adsorption and desorption processes, a problem arises: the accumulation of flow electrodes within the microchannel. Flow electrodes typically used in flow electrode capacitive desalination are made of carbon-based materials such as activated carbon, carbon black, activated carbon fiber, carbon nanotubes, and graphene. Activated carbon is primarily used due to material availability and cost-effectiveness.

[0008] The above activated carbon-based flow electrode flows through the microchannel in the form of a slurry. However, the slurry-type flow electrode may cause sedimentation within the microchannel during operation. If sedimentation continues, the activated carbon accumulates, clogging the microchannel and causing the activated carbon to accumulate on the ion exchange membrane in contact with the microchannel. This clogging of the microchannel and contamination of the ion exchange membrane reduces the ion adsorption and desorption efficiency, making it difficult to secure the economic feasibility of the process.

[0009] One embodiment of the present invention provides a flow electrode capacitive desalination device capable of preventing flow electrodes from accumulating within a flow electrode path during operation.

[0010] Another embodiment of the present invention provides a flow electrode capacitive desalination method capable of preventing accumulation of flow electrodes within a flow electrode path during operation.

[0011] One aspect of the present invention is:

[0012] Electrolyte path, which is the passageway for the electrolyte to be desalinated;

[0013] A cation exchange membrane and an anion exchange membrane arranged side by side and spaced apart from each other to limit the above electrolyte path;

[0014] A flow cathode channel, which is a passage for the flow cathode, is arranged parallel to the electrolyte channel and spaced apart from each other with the cation exchange membrane in between;

[0015] A flow anode channel, which is a passage for the movement of a flow anode, is arranged parallel to the electrolyte channel and spaced apart from each other with the anion exchange membrane in between;

[0016] A cathode current collector that is arranged parallel to the cathode current collector and spaced apart from the cathode current collector, which defines the cathode flow path together with the cathode current exchange membrane;

[0017] A cathode current collector that is arranged parallel to the anion exchange membrane and spaced apart from the anion exchange membrane, defining the flow anode path together with the anion exchange membrane;

[0018] A power supply configured to apply a potential difference between the negative current collector and the positive current collector; and

[0019] A flow electrode capacitive desalination device is provided, which includes a gas supply unit configured to supply gas to the flow cathode path and the flow anode path.

[0020] The above-mentioned flow cathode and the above-mentioned flow anode may each include an electrode active material and a fluid.

[0021] The above electrode active material may include activated carbon, carbon fiber, carbon aerogel, carbon nanotubes, graphene, graphite powder, metal oxide powder, or a combination thereof.

[0022] The above fluids may each include H2O, Li2CO3, LiOH, NaCl, H2SO4, HCl, NaOH, KOH, Na2NO3 or a combination thereof.

[0023] The above flow electrode capacitor type desalination device may further include an electrolyte supply unit configured to supply electrolyte to the electrolyte channel and also recover electrolyte discharged from the electrolyte channel.

[0024] The above flow electrode capacitive desalination device may further include a flow cathode supply unit configured to supply a flow cathode to the flow cathode channel and also recover the flow cathode discharged from the flow cathode channel, and a flow anode supply unit configured to supply a flow anode to the flow anode channel and also recover the flow anode discharged from the flow anode channel.

[0025] The above flow electrode capacitive desalination device may further include an electrolyte supply pipe arranged between the outlet of the electrolyte supply unit and the inlet of the electrolyte channel, an electrolyte discharge pipe arranged between the outlet of the electrolyte channel and the inlet of the electrolyte supply unit, a flow cathode supply pipe arranged between the outlet of the flow cathode supply unit and the inlet of the flow cathode channel, a flow cathode discharge pipe arranged between the outlet of the flow cathode channel and the inlet of the flow cathode supply unit, a flow anode supply pipe arranged between the outlet of the flow cathode supply unit and the inlet of the flow anode channel, a flow anode discharge pipe arranged between the outlet of the flow anode channel and the inlet of the flow anode supply unit, a first gas supply pipe arranged between the gas supply unit and the inlet of the flow cathode channel, and a second gas supply pipe arranged between the gas supply unit and the flow anode channel.

[0026] The above flow electrode capacitive desalination device may further include a flow electrode regeneration unit fluidly connected to the flow cathode supply pipe and the flow anode supply pipe.

[0027] The above flow electrode capacitive desalination device may further include a pressure gauge installed in each of the flow cathode supply pipe, the flow cathode discharge pipe, the flow anode supply pipe, the flow anode discharge pipe, the first gas supply pipe, and the second gas supply pipe.

[0028] The first gas supply pipe may be in fluid communication with the flow cathode supply pipe, and the second gas supply pipe may be in fluid communication with the flow anode supply pipe.

[0029] The above flow electrode capacitor type desalination device may further include a valve installed in each of the first gas supply pipe and the second gas supply pipe.

[0030] The above flow electrode capacitor type desalination device may further include a control unit.

[0031] The control unit may be configured to operate the valves to supply the gas from the gas supply unit to at least one of the flow cathode path and the flow anode path for a predetermined time in a predetermined time cycle.

[0032] The control unit may be configured to calculate a pressure difference between the inlet and outlet of the flow cathode path from a pressure gauge installed in the flow cathode supply pipe and another pressure gauge installed in the flow cathode discharge pipe, and if the pressure difference is greater than a reference value, operate the valve to supply the gas from the gas supply unit to the flow cathode path.

[0033] The control unit may be configured to calculate a pressure difference between the inlet and outlet of the flow anode flow path from a pressure gauge installed in the flow anode supply pipe and another pressure gauge installed in the flow anode discharge pipe, and supply the gas from the gas supply unit to the flow anode flow path when the pressure difference is greater than a reference value.

[0034] The above control unit may be configured to control the pressure of the gas supplied from the gas supply unit to the flow cathode channel and the pressure of the gas supplied from the gas supply unit to the flow anode channel, respectively, using a pressure gauge installed in the first gas supply pipe and another pressure gauge installed in the second gas supply pipe.

[0035] The gas may comprise air, nitrogen or a combination thereof.

[0036] The above-mentioned flow cathode path and the above-mentioned flow anode path may be meandering paths.

[0037] Another aspect of the present invention is:

[0038] A flow electrode capacitive desalination method using the above flow electrode capacitive desalination device,

[0039] A flow electrode capacitive desalination method is provided, including a step (S100) of intermittently supplying gas from the gas supply unit to at least one of the flow cathode channel and the flow anode channel during operation of the flow electrode capacitive desalination device.

[0040] The above step (S100) may be a step of supplying the gas from the gas supply unit to at least one of the flow cathode path and the flow anode path for a predetermined time in a predetermined time cycle.

[0041] The above step (S100) may include a step (S110) of measuring a pressure difference (△P1) between the inlet and the outlet of the flow cathode channel and a pressure difference (△P2) between the inlet and the outlet of the flow anode channel, and a step (S120) of supplying the gas from the gas supply unit to the flow cathode channel or the flow anode channel if the pressure difference (△P1) or the pressure difference (△P2) is greater than a reference value.

[0042] The flow electrode capacitive desalination device and the flow electrode capacitive desalination method according to one embodiment of the present invention can prevent accumulation of flow electrodes in the flow electrode path during operation, clean the flow electrode path, thereby increasing the efficiency of ion adsorption and desorption, reduce contamination of the ion exchange membrane in contact with the flow electrode, thereby lowering the resistance of the ion exchange membrane, and facilitate the flow of ions through the ion exchange membrane.

[0043] FIG. 1 is a schematic drawing of a flow electrode capacitive desalination device according to one embodiment of the present invention.

[0044] Figure 2 is a photograph showing the state of the surface of the current collector and the ion exchange membrane when the flow electrode capacitive desalination device is operated according to Example 1.

[0045] Figure 3 is a photograph showing the state of the surface of the current collector and the ion exchange membrane when the flow electrode capacitor desalination device was operated according to Comparative Example 1.

[0046] Hereinafter, a flow electrode capacitor type desalination device according to one embodiment of the present invention will be described in detail with reference to the drawings.

[0047] In this specification, “flow electrode” means an electrode that moves in the form of slurry rather than a fixed electrode, and is a general term for a flow cathode and a flow anode.

[0048] Also, in this specification, “fluid communication” means that two or more pipes are connected so that fluid can flow therethrough.

[0049] FIG. 1 is a schematic drawing of a flow electrode capacitor type desalination device (100) according to one embodiment of the present invention.

[0050] Referring to FIG. 1, a flow electrode capacitive desalination device (100) according to one embodiment of the present invention includes an electrolyte flow path (110), a cation exchange membrane (CEM) (121), an anion exchange membrane (AEM) (122), a flow cathode flow path (151), a flow anode flow path (152), a cathode current collector (131), an anode current collector (132), a power supply unit (potentiostat) (not shown), and a gas supply unit (not shown).

[0051] The electrolyte path (110) may be a passageway for the electrolyte to be desalinated.

[0052] As the electrolyte, brine containing a large amount of salt or fresh water containing a small amount of salt can be used.

[0053] The cation exchange membrane (121) and the anion exchange membrane (122) define the electrolyte path (110) and can be arranged side by side and spaced apart from each other.

[0054] The cation exchange membrane (121) can be configured to block the movement of substances between the flow cathode path (151) and the electrolyte path (110) and selectively allow only cations to pass through.

[0055] The anion exchange membrane (122) can be configured to block the movement of substances between the flow anode channel (152) and the electrolyte channel (110) and selectively allow only anions to pass through.

[0056] The flow cathode path (151) is arranged parallel to the electrolyte path (110) and spaced apart from each other with the cation exchange membrane (121) in between, and may be a passage for the flow cathode (141).

[0057] The flow anode path (152) is arranged parallel to the electrolyte path (110) and spaced apart from each other with the anion exchange membrane (122) in between, and may be a passage for the flow anode (142).

[0058] The flow cathode channel (151) and the flow anode channel (152) may each be serpentine channels. Specifically, serpentine grooves may be formed on the facing surfaces of the cathode current collector (131) and optionally the cation exchange membrane (121) so as to face each other, thereby forming a serpentine channel. Similarly, serpentine grooves may be formed on the facing surfaces of the anode current collector (132) and optionally the anion exchange membrane (122) so as to face each other, thereby forming a serpentine channel.

[0059] The flow cathode (141) and the flow anode (142) may each include an electrode active material (141a, 142a) and a fluid (141b, 142b).

[0060] The flow cathode (141) and the flow anode (142) may each have a slurry form in which electrode active materials (141a, 142a) are dispersed in a fluid (141b, 142b).

[0061] The electrode active material (141a, 142a) may include activated carbon, carbon fiber, carbon aerogel, carbon nanotube, graphene, graphite powder, metal oxide powder, or a combination thereof.

[0062] The fluid (141b, 142b) may include H2O, Li2CO3, LiOH, NaCl, H2SO4, HCl, NaOH, KOH, Na2NO3, or a combination thereof. In particular, the fluid may be brine containing a large amount of salt (particularly, NaCl) or fresh water containing a small amount of salt.

[0063] The cathode current collector (131) defines the flow cathode path (151) together with the cation exchange membrane (121), and can be arranged side by side and spaced apart from the cation exchange membrane (121).

[0064] The cathode current collector (132) defines the flow cathode path (152) together with the anion exchange membrane (122), and can be arranged side by side and spaced apart from the anion exchange membrane (122).

[0065] The above power supply unit may be configured to apply an electrical potential difference between the negative current collector (131) and the positive current collector (132).

[0066] The above gas supply unit can be configured to supply gas to the flow cathode path (151) and the flow anode path.

[0067] Additionally, the flow electrode capacitor type deionization device (100) may further include an electrolyte supply unit (160).

[0068] The electrolyte supply unit (160) may be configured to supply electrolyte to the electrolyte path (110) and also recover electrolyte discharged from the electrolyte path (110).

[0069] In addition, the flow electrode capacitor type desalination device (100) may further include a flow cathode supply unit (171) and a flow anode supply unit (172).

[0070] The flow cathode supply unit (171) can be configured to supply the flow cathode (141) to the flow cathode path (151) and also to recover the flow cathode (141) discharged from the flow cathode path (151).

[0071] The flow anode supply unit (172) can be configured to supply the flow anode (142) to the flow anode path (152) and also to recover the flow anode (142) discharged from the flow anode path (152).

[0072] In addition, the flow electrode capacitive desalination device (100) may further include an electrolyte supply pipe (L11), an electrolyte discharge pipe (L12), a flow cathode supply pipe (L21), a flow cathode discharge pipe (L22), a flow anode supply pipe (L31), a flow anode discharge pipe (L32), a first gas supply pipe (L41), and a second gas supply pipe (L42).

[0073] The electrolyte supply pipe (L11) can be placed between the outlet of the electrolyte supply unit (160) and the inlet of the electrolyte path (110).

[0074] The electrolyte discharge pipe (L12) can be placed between the outlet of the electrolyte path (110) and the inlet of the electrolyte supply unit (160).

[0075] The flow cathode supply pipe (L21) can be placed between the outlet of the flow cathode supply unit (171) and the inlet of the flow cathode path (151).

[0076] The flow cathode discharge pipe (L22) can be placed between the outlet of the flow cathode path (151) and the inlet of the flow cathode supply unit (171).

[0077] The flow anode supply pipe (L31) can be placed between the outlet of the flow anode supply unit (172) and the inlet of the flow anode flow path (152).

[0078] The flow anode discharge pipe (L32) can be placed between the outlet of the flow anode path (152) and the inlet of the flow anode supply unit (172).

[0079] The first gas supply pipe (L41) can be placed between the gas supply section and the inlet of the flow cathode path (151).

[0080] The second gas supply pipe (L42) can be placed between the gas supply section and the inlet of the flow anode path (152).

[0081] Additionally, the flow electrode capacitor type desalination device (100) may further include a flow electrode regeneration unit (not shown).

[0082] The above flow electrode regeneration unit may be in fluid communication with the flow cathode supply pipe (L21) and the flow anode supply pipe (L31). Specifically, the flow cathode (141) discharged from the flow cathode supply unit (171) and the flow anode (142) discharged from the flow anode supply unit (172) are introduced into the flow electrode regeneration unit, and an electrical short circuit occurs between differently charged electrode active materials (141a, 142a) due to physical contact between the flow cathode (141) and the flow anode (142) within the flow electrode regeneration unit, and the cations and anions adsorbed on the surface of the electrode active materials (141a, 142a) are released into the fluid (141a, 142b), so that the adsorption capacity of the electrode active materials (141a, 142a) can be regenerated.

[0083] Meanwhile, the flow electrode regeneration unit may not be a separate member from the flow cathode supply unit (171) and the flow anode supply unit (172), but may be an integrated member in which the flow cathode supply unit (171) and the flow anode supply unit (172) are formed. In this case, the flow cathode (141) discharged from the flow cathode channel (151) and the flow anode (142) discharged from the flow anode channel (152) may be recovered in the flow electrode regeneration unit, regenerated, and then supplied again to the flow cathode channel (151) and the flow anode channel (152), respectively.

[0084] Therefore, the flow cathode path (141) supplied to the flow cathode path (151) and the flow anode (142) resupplied to the flow anode path (152) can maintain the existing desalination performance.

[0085] If this desalination process continues, the ion concentration in the fluid (141b, 142b) may become excessively high, which may result in a deterioration in desalination performance. To prevent this, when the concentration of the fluid (141b) in the flow cathode (141) recovered by the flow cathode supply unit (171) and the concentration of the fluid (142b) in the flow anode (142) recovered by the flow anode supply unit (172) exceed a limit concentration, a certain amount of the flow electrodes (141, 142) may be removed from the flow cathode supply unit (171) and the flow anode supply unit (172) (or the flow electrode regeneration unit when these are integrated) to separate the concentrated fluid (141b, 142b) from the electrode active material (141a, 142a) and discharge it to the outside. In addition, the flow electrodes (141, 142) from which the concentrated fluid (141b, 142b) has been removed can be regenerated to their original composition by adding new fluid (141b, 142b) in the above-described flow electrode regeneration unit, and then reintroduced into the flow cathode path (151) and the flow anode path (152).

[0086] Therefore, the flow electrode capacitor type desalination device (100) can continuously perform the desalination process while minimizing the amount of flow electrodes (141, 142) consumed.

[0087] Additionally, the flow electrode capacitor type desalination device (100) may further include a pressure gauge (PG1, PG2, PG3, PG4, PG5, PG6).

[0088] A pressure gauge (PG1) can be installed in the flow cathode supply pipe (L21).

[0089] A pressure gauge (PG2) can be installed in the flow cathode discharge pipe (L22).

[0090] A pressure gauge (PG3) can be installed in the first gas supply pipe (L41).

[0091] A pressure gauge (PG4) can be installed in the flow anode supply pipe (L31).

[0092] A pressure gauge (PG5) can be installed on the flow anode discharge pipe (L32).

[0093] A pressure gauge (PG6) can be installed in the second gas supply pipe (L42).

[0094] Additionally, the flow electrode capacitor type desalination device (100) may further include a pump (P1, P2).

[0095] The pump (P1) can be installed in the flow cathode supply pipe (L21).

[0096] The pump (P2) can be installed in the flow anode supply pipe (L31).

[0097] The above first gas supply pipe can be in fluid communication with the flow cathode supply pipe (L21).

[0098] The above second gas supply pipe can be in fluid communication with the flow anode supply pipe (L31).

[0099] Additionally, the flow electrode capacitor type desalination device (100) may further include valves (V1, V2).

[0100] A valve (V1) can be installed in the first gas supply pipe (L41).

[0101] The valve (V2) can be installed in the second gas supply pipe (L42).

[0102] Additionally, the flow electrode capacitor type desalination device (100) may further include a control unit (not shown).

[0103] The above control unit may be configured to operate the valves (V1, V2) to supply the gas from the gas supply unit to at least one of the flow cathode channel (151) and the flow anode channel (152) for a predetermined time period at a predetermined time cycle.

[0104] In addition, the control unit may be configured to calculate the pressure difference between the inlet and outlet of the flow cathode path (151) from the pressure gauge (PG1) installed in the flow cathode supply pipe (L21) and the pressure gauge (PG2) installed in the flow cathode discharge pipe (L22), and if the pressure difference is greater than a reference value, operate the valve (V1) to supply the gas from the gas supply unit to the flow cathode path (151).

[0105] In addition, the control unit may be configured to calculate the pressure difference between the inlet and outlet of the flow anode passage (152) from the pressure gauge (PG4) installed in the flow anode supply pipe (L31) and the pressure gauge (PG5) installed in the flow anode discharge pipe (L32), and if the pressure difference is greater than a reference value, operate the valve (V2) to supply the gas from the gas supply unit to the flow anode passage (152).

[0106] In addition, the control unit may be configured to control the pressure of the gas supplied from the gas supply unit to the flow cathode channel (151) and the pressure of the gas supplied from the gas supply unit to the flow anode channel (152), respectively, using the pressure gauge (PG3) installed in the first gas supply pipe (L41) and the pressure gauge (PG6) installed in the second gas supply pipe (L42).

[0107] The gas may comprise air, nitrogen or a combination thereof.

[0108] Hereinafter, a flow electrode capacitive desalination method according to one embodiment of the present invention will be described in detail with reference to the drawings.

[0109] Referring to FIG. 1, a flow electrode capacitive desalination method according to one embodiment of the present invention is a flow electrode capacitive desalination method using the above-described flow electrode capacitive desalination device (100).

[0110] The above flow electrode capacitive desalination method includes a step (S100) of intermittently supplying gas from the gas supply unit to at least one of the flow cathode flow path (151) and the flow anode flow path (152) during operation of the flow electrode capacitive desalination device (100).

[0111] As an example, the step (S100) may be a step of supplying the gas from the gas supply unit to at least one of the flow cathode path (151) and the flow anode path (152) for a predetermined time in a predetermined time cycle.

[0112] As another example, the step (S100) may include a step (S110) of measuring a pressure difference (△P1) between the inlet and outlet of the flow cathode channel (151) and a pressure difference (△P2) between the inlet and outlet of the flow anode channel (152), and a step (S120) of supplying the gas from the gas supply unit to the flow cathode channel (151) or the flow anode channel (152) if the pressure difference (△P1) or the pressure difference (△P2) is greater than a reference value.

[0113] Hereinafter, the present invention will be described in more detail through examples. These examples are intended to explain the present invention more specifically, and the scope of the present invention is not limited to these examples.

[0114] Example 1: Manufacturing and operation of a flow electrode capacitive desalination device

[0115] A flow electrode capacitive desalination device having the structure of Fig. 1 was manufactured and operated. Specifically, a meandering flow electrode microchannel (2 mm wide × 2 mm deep) was formed on a pair of current collectors (100 mm wide × 100 mm long) made of graphite. In addition, a cation exchange membrane and an anion exchange membrane (Toray Advanced Materials Co., Ltd.) (100 mm wide × 100 mm long) were respectively placed in contact with the flow electrode microchannel formed on each of the current collectors, and a gasket and a spacer were placed between the cation exchange membrane and the anion exchange membrane. The operation of the flow electrode capacitive desalination device manufactured above was performed by supplying 3,000 mg / L of lithium carbonate (Li2CO3) as an electrolyte to the electrolyte path at a flow rate of 8 mL / min under a constant current condition of 200 mA using a power supply device (potentiostat), and activated carbon (specific surface area: 1,573 m) as an electrode active material in distilled water (H2O) as a fluid for the flow electrode. 2 / g) was dispersed at a concentration of 13 wt% and supplied to the flow electrode path at a flow rate of 25 mL / min.

[0116] The gas supply unit was operated for 30 minutes after the start of operation and then periodically repeated the process of supplying air for 5 minutes. The operation continued without interruption even while air was supplied, and the air supply amount was fixed at 0.7 bar. After the operation until the conductivity of the electrolyte did not change (i.e., the ion adsorption completion point, 10 μS / cm), the accumulated power was calculated, and the results are shown in Table 1 below. In addition, after the operation, the current collector and the ion exchange membrane were separated from the flow electrode capacitive desalination device, and a photograph was taken so that the flow electrode path was visible, which is shown in Fig. 2.

[0117] Example 2: Manufacturing and operation of a flow electrode capacitive desalination device

[0118] The flow electrode capacitive desalination device manufactured in Example 1 was operated in the same manner as in Example 1, except that the air supply method was changed as follows. That is, the gas supply unit was automatically operated when the pressure difference between the inlet and outlet of the flow electrode supply unit was 0.1 bar or more, and was stopped when the pressure difference was 0.01 bar or less. Operation was continued without interruption even while air was supplied, and the air supply amount was fixed at 0.7 bar.

[0119] Comparative Example 1: Manufacturing and Operation of a Flow Electrode Capacitive Desalination Device

[0120] The flow electrode capacitive desalination device manufactured in Example 1 was operated in the same manner as in Example 1, except that air was not supplied to the flow electrode path. In addition, after operation, the current collector and the ion exchange membrane were separated from the flow electrode capacitive desalination device, and a photograph was taken to show the flow electrode path, which is shown in Fig. 3.

[0121] Time required for ion adsorption to be completed (hr) Cumulative power until ion adsorption is completed (Wh) Example 1 12.5 6.8 Example 2 11.1 7.7 Comparative example 120.2 9.9

[0122]

[0123] Referring to Table 1 above, the flow electrode capacitive desalination method performed in Examples 1 and 2 was found to have a shorter time required until ion adsorption was completed and a smaller accumulated power amount until ion adsorption was completed compared to the flow electrode capacitive desalination method performed in Comparative Example 1.

[0124] In addition, referring to FIGS. 2 and 3, it was shown that the flow electrode capacitive desalination method performed in Examples 1 and 2 had a superior cleaning effect compared to the flow electrode capacitive desalination method performed in Comparative Example 1.

[0125] While the present invention has been described with reference to the drawings and examples, these are merely exemplary, and those skilled in the art will understand that various modifications and equivalent implementations are possible. Therefore, the true scope of technical protection of the present invention should be determined by the technical spirit of the appended claims.

[0126] [Explanation of symbols]

[0127] 100: Flow electrode capacitive desalination device 110: Electrolyte flow path

[0128] 121, 122: Ion exchange membrane 131, 132: Current collector

[0129] 141, 142: Flow electrode 141a, 142a: Electrode active material

[0130] 141b, 142b: Fluid 151, 152: Flow electrode path

[0131] 160: Electrolyte supply unit 171, 172: Flow electrode supply unit

[0132] P1, P2: Pump V1, V2: Valve

[0133] PG1~PG6: Pressure gauges L11, L21, L31, L41, L42: Supply pipes

[0134] L12, L22, L32: exhaust pipe

Claims

1. Electrolyte flow path, which is the passageway for the electrolyte to be desalinated; A cation exchange membrane and an anion exchange membrane arranged side by side and spaced apart from each other to limit the above electrolyte path; A flow cathode channel, which is a passage for the flow cathode, is arranged parallel to the electrolyte channel and spaced apart from each other with the cation exchange membrane in between; A flow anode channel, which is a passage for the movement of a flow anode, is arranged parallel to the electrolyte channel and spaced apart from each other with the anion exchange membrane in between; A cathode current collector that is arranged parallel to the cathode current collector and spaced apart from the cathode current collector, which defines the cathode flow path together with the cathode current exchange membrane; A cathode current collector that is arranged parallel to the anion exchange membrane and spaced apart from the anion exchange membrane, defining the flow anode path together with the anion exchange membrane; A power supply configured to apply a potential difference between the negative current collector and the positive current collector; and A flow electrode capacitive desalination device comprising a gas supply unit configured to supply gas to the above flow cathode path and the above flow anode path.

2. In paragraph 1, The above flow cathode and the flow anode are a flow electrode capacitive desalination device, each containing an electrode active material and a fluid.

3. In paragraph 2, A flow electrode capacitive desalination device, wherein the electrode active material comprises activated carbon, carbon fiber, carbon aerogel, carbon nanotube, graphene, graphite powder, metal oxide powder or a combination thereof.

4. In paragraph 2, A flow electrode capacitive desalination device wherein the fluid comprises H2O, Li2CO3, LiOH, NaCl, H2SO4, HCl, NaOH, KOH, Na2NO3 or a combination thereof.

5. In paragraph 1, A flow electrode capacitive desalination device further comprising an electrolyte supply unit configured to supply electrolyte to the electrolyte path and also recover electrolyte discharged from the electrolyte path.

6. In paragraph 1, A flow electrode capacitive desalination device further comprising a flow cathode supply unit configured to supply a flow cathode to the flow cathode path and also recover a flow cathode discharged from the flow cathode path, and a flow anode supply unit configured to supply a flow anode to the flow anode path and also recover a flow anode discharged from the flow anode path.

7. In paragraph 6, A flow electrode capacitive desalination device further comprising: an electrolyte supply pipe arranged between the outlet of the electrolyte supply unit and the inlet of the electrolyte channel, an electrolyte discharge pipe arranged between the outlet of the electrolyte channel and the inlet of the electrolyte supply unit, a flow cathode supply pipe arranged between the outlet of the flow cathode supply unit and the inlet of the flow cathode channel, a flow cathode discharge pipe arranged between the outlet of the flow cathode channel and the inlet of the flow cathode supply unit, a flow anode supply pipe arranged between the outlet of the flow cathode supply unit and the inlet of the flow anode channel, a flow anode discharge pipe arranged between the outlet of the flow anode channel and the inlet of the flow anode supply unit, a first gas supply pipe arranged between the gas supply unit and the inlet of the flow cathode channel, and a second gas supply pipe arranged between the gas supply unit and the flow anode channel.

8. In paragraph 7, A flow electrode capacitive desalination device further comprising a flow electrode regeneration unit fluidly connected to the flow cathode supply pipe and the flow anode supply pipe.

9. In paragraph 7, A flow electrode capacitive desalination device further comprising a pressure gauge installed in each of the flow cathode supply pipe, the flow cathode discharge pipe, the flow anode supply pipe, the flow anode discharge pipe, the first gas supply pipe, and the second gas supply pipe.

10. In paragraph 9, A flow electrode capacitive desalination device in which the first gas supply pipe is in fluid communication with the flow cathode supply pipe, and the second gas supply pipe is in fluid communication with the flow anode supply pipe.

11. In paragraph 9, A flow electrode capacitor type desalination device further comprising a valve installed in each of the first gas supply pipe and the second gas supply pipe.

12. In paragraph 11, A flow electrode capacitive desalination device further comprising a control unit.

13. In paragraph 12, A flow electrode capacitive desalination device, wherein the control unit is configured to operate the valves to supply the gas from the gas supply unit to at least one of the flow cathode path and the flow anode path for a predetermined time in a predetermined time cycle.

14. In paragraph 12, A flow electrode capacitive desalination device configured such that the control unit calculates a pressure difference between the inlet and outlet of the flow cathode path from a pressure gauge installed in the flow cathode supply pipe and another pressure gauge installed in the flow cathode discharge pipe, and if the pressure difference is greater than a reference value, operates the valve to supply the gas from the gas supply unit to the flow cathode path.

15. In paragraph 12, A flow electrode capacitive desalination device configured to calculate a pressure difference between the inlet and outlet of the flow anode flow path from a pressure gauge installed in the flow anode supply pipe and another pressure gauge installed in the flow anode discharge pipe, and supply the gas from the gas supply section to the flow anode flow path when the pressure difference is greater than a reference value.

16. In paragraph 12, A flow electrode capacitive desalination device, wherein the control unit is configured to control the pressure of gas supplied from the gas supply unit to the flow cathode channel and the pressure of gas supplied from the gas supply unit to the flow anode channel, respectively, using a pressure gauge installed in the first gas supply pipe and another pressure gauge installed in the second gas supply pipe.

17. In paragraph 1, A flow electrode capacitive desalination device wherein the gas comprises air, nitrogen or a combination thereof.

18. In paragraph 1, A flow electrode capacitive desalination device in which the above flow cathode path and the above flow anode path are meandering paths.

19. A flow electrode capacitive desalination method using a flow electrode capacitive desalination device according to Article 1, A flow electrode capacitive desalination method comprising a step (S100) of intermittently supplying gas from the gas supply unit to at least one of the flow cathode channel and the flow anode channel during operation of the flow electrode capacitive desalination device.

20. In paragraph 19, The above step (S100) is a flow electrode capacitive desalination method in which the gas is supplied from the gas supply unit to at least one of the flow cathode path and the flow anode path for a predetermined time in a predetermined time cycle.

21. In paragraph 19, The above step (S100) is a flow electrode capacitive desalination method including a step (S110) of measuring a pressure difference (△P1) between the inlet and the outlet of the flow cathode channel and a pressure difference (△P2) between the inlet and the outlet of the flow anode channel, and a step (S120) of supplying the gas from the gas supply unit to the flow cathode channel or the flow anode channel if the pressure difference (△P1) or the pressure difference (△P2) is greater than a reference value.

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