WO2022216030A1

WO2022216030A1 - Filter for water treatment device

Info

Publication number: WO2022216030A1
Application number: PCT/KR2022/004929
Authority: WO
Inventors: Jinhyun Lee; Kiwon Yu; Hyungki Hong; Jongpil Kim
Original assignee: LG Electronics Inc
Current assignee: LG Electronics Inc
Priority date: 2021-04-06
Filing date: 2022-04-06
Publication date: 2022-10-13
Anticipated expiration: 2023-10-06
Also published as: KR20220138593A; KR102528672B1

Abstract

Disclosed is a filter for a water treatment device that is applicable to water purifiers, etc. The filter for a water treatment device includes a chamber including a water inlet and a water outlet, an electrode assembly disposed in the chamber so as to come into contact with feed water fed through the water inlet, the electrode assembly including a plurality of electrode units, and a power connector configured to supply power to the electrode assembly, wherein each electrode unit includes a plate-shaped electrode and an ion exchange membrane configured to filter ions contained in the feed water and block contact between the feed water and the electrode.

Description

FILTER FOR WATER TREATMENT DEVICE

The present disclosure relates to a filter for a water treatment device that is applicable to water purifiers, etc.

In general, a water treatment device for producing purified water by treating raw water, such as a water purifier, may have various forms. Recently, among methods applicable to such water treatment devices, a method that has recently been spotlighted is a deionization method, such as an EDI (electro-deionization), CEDI (continuous electro- deionization) or CDI (capacitive deionization) method.

Among these, the CDI method is a method of removing ions (contaminants) in water based on a principle in which ions are adsorbed on and desorbed from the surface of an electrode by electrical force.

When treatment water containing ions is made to pass between electrodes (an anode and a cathode) while voltage is applied to the electrodes, anions and cations move to the anode and the cathode, respectively, and are adsorbed thereon. The ions in the treatment water can be removed through this adsorption process.

Under the ideal condition for the adsorption operation of the CDI module, since a cation exchange membrane is located on the cathode, only cations such as calcium ions (Ca²⁺) and magnesium ions (Mg²⁺) can be adsorbed to the cathode without chemical reaction.

However, in practice, a bypass flow path may be formed between the cation exchange membrane and the cathode. Raw water (feed water) may be fed through this bypass flow path.

Anions such as carbonate ions (CO₃ ^2-) are present in the feed water. Among the anions, carbonate ions (CO₃ ^2-) react with calcium ions (Ca²⁺) that have passed through the cation exchange membrane based on electrical attraction to produce calcium carbonate (CaCO₃), which adheres in the form of scale to the surface of the cathode.

Ultimately, the surface area of the cathode may be reduced by the scale, the gap between the cation exchange membrane and the cathode may be widened, the bypass flow path may be gradually increased, and the production of scale on the cathode may be accelerated as time passes. Accordingly, the performance of the CDI module may be deteriorated because the cathode becomes increasingly unusable in proportion to the area of the cathode on which scale forms.

Therefore, there is a need to solve these problems.

One technical task of the present disclosure is to provide a filter for a water treatment device that is capable of minimizing a deterioration in performance due to the operation of a CDI (capacitive deionization) module.

Another technical task of the present disclosure is to provide a filter for a water treatment device that is capable of increasing the lifetime of an electrode by reducing formation of scale on the surface of the electrode.

Another technical task of the present disclosure is to provide a filter for a water treatment device that is capable of blocking a bypass flow path through which raw water that is not filtered through the ion exchange membrane is fed between the ion exchange membrane and the electrode.

According to one embodiment of the present disclosure, a structure in which an electrode disposed in a CDI (capacitive deionization) module is surrounded with an ion exchange membrane is provided.

According to an embodiment of the present disclosure, the structure in which the electrode is surrounded with the ion exchange membrane can reduce scale formation. For example, a structure in which a cathode is surrounded with a cation exchange membrane can block the flow of anions to the cathode, thereby reducing scale production. Accordingly, the lifespan of the CDI module can be improved.

Specifically, according to an embodiment of the present disclosure, by proposing a structure in which an electrode is surrounded with an ion exchange membrane, it is possible to block the bypass flow path through which raw water that is not filtered through the ion exchange membrane is fed between the ion exchange membrane and the electrode.

At this time, only cations that have passed through the cation exchange membrane based on electrical attraction pass through the cathode, whereas only the anions that pass through the anion exchange membrane may be present at the anode. Accordingly, it is possible to minimize the production of scale and ancillary materials that may occur due to the presence of different ions on the electrode surfaces when the polarity of the electrodes is changed.

Scale production does not occur on the electrode surface, thus minimizing the reduction in the original area of the electrode, reducing degradation in the performance of the CDI module, and improving the durability of the CDI module.

In one technical aspect of the present disclosure, provided is a filter for a water treatment device including a chamber including a water inlet and a water outlet, an electrode assembly disposed in the chamber so as to come into contact with feed water fed through the water inlet, the electrode assembly including a plurality of electrode units, and a power connector configured to supply power to the electrode assembly, wherein each electrode unit includes a plate-shaped electrode and an ion exchange membrane configured to filter ions contained in the feed water and block contact between the feed water and the electrode.

The ion exchange membrane may seal the electrode so as to prevent the feed water from penetrating into the electrode.

The electrode may include a current collector and an activated carbon coating layer disposed on at least one surface of the current collector.

The ion exchange membrane may surround an entire area of the activated carbon coating layer.

The ion exchange membrane may include an extension portion that extends toward a side end of the current collector.

The filter may further include a sealing member disposed at a side end of the ion exchange membrane.

The sealing member may contain at least one of silicone, Teflon, PTFE, PTEE, rubber, EPDM, and polyester.

The sealing member may be divided into two portions at both sides of the extension portion.

The two divided sealing members may be provided so as to be pressed against each other.

In another technical aspect of the present disclosure, provided is a filter for a water treatment device including a chamber including a water inlet and a water outlet, an electrode assembly disposed in the chamber so as to come into contact with feed water fed through the water inlet, the electrode assembly including a first electrode unit, a second electrode unit, and a spacer disposed between the first electrode unit and the second electrode unit, and a power connector configured to supply power to the electrode assembly, wherein the first electrode unit includes a first electrode and a cation exchange membrane sealing the first electrode, and the second electrode unit includes a second electrode and an anion exchange membrane sealing the second electrode.

The cation exchange membrane may seal the first electrode so as to prevent the feed water from penetrating into the first electrode, and the anion exchange membrane may seal the second electrode to prevent the feed water from penetrating into the second electrode.

The cation exchange membrane and the anion exchange membrane may include extension portions that extend in a longitudinal direction of the first electrode and the second electrode, respectively.

The filter may further include a sealing member disposed at a side end of the cation exchange membrane or the anion exchange membrane.

The sealing member may be divided into two portions at both side ends of the cation exchange membrane or the anion exchange membrane.

According to one embodiment of the present disclosure, the following effects can be obtained.

First, a structure in which an electrode is surrounded with an ion exchange membrane can reduce scale formation. For example, a structure in which a cathode is surrounded with a cation exchange membrane can block the flow of anions to the cathode, thereby reducing scale production. Accordingly, the lifespan of the CDI module can be improved.

According to an embodiment of the present disclosure, by proposing a structure in which an electrode is surrounded with an ion exchange membrane, it is possible to block the bypass flow path through which raw water that is not filtered through the ion exchange membrane is fed between the ion exchange membrane and the electrode.

According to an embodiment of the present disclosure, only cations that have passed through the cation exchange membrane based on electrical attraction pass through the cathode, whereas only the anions that pass through the anion exchange membrane may be present at the anode. Accordingly, it is possible to minimize the production of scale and ancillary materials that may occur due to the presence of different ions on the electrode surfaces when the polarity of the electrodes is changed.

Furthermore, according to another embodiment of the present disclosure, there are additional effects not mentioned herein. Those of ordinary skill in the art may understand it through the full text of the specification and drawings.

FIG. 1 is a partially cutaway perspective view illustrating a filter for a water treatment device according to an embodiment of the present disclosure;

FIG. 2 is a plan view illustrating an electrode unit of a filter for a water treatment device according to an embodiment of the present disclosure;

FIG. 3 is a cross-sectional view illustrating an electrode unit of a filter for a water treatment device according to an embodiment of the present disclosure;

FIG. 4 is a cross-sectional view illustrating an electrode assembly of a filter for a water treatment device according to an embodiment of the present disclosure;

FIG. 5 is a conceptual diagram illustrating a state in which water is purified through the filter for a water treatment device shown in FIG. 4;

FIG. 6 is a conceptual diagram illustrating a state in which the filter for a water treatment device shown in FIG. 4 is regenerated;

FIG. 7 is a flowchart illustrating a process of manufacturing an electrode assembly of a filter for a water treatment device according to an embodiment of the present invention;

FIGS. 8 and 9 are cross-sectional schematic views illustrating a part of the process illustrated in FIG. 7;

FIG. 10 is a schematic diagram illustrating a state in which a bypass flow path is formed in an electrode assembly of a conventional filter for a water treatment device as a comparative example;

FIG. 11 is an image showing an electrode surface of a conventional filter for a water treatment device;

FIG. 12 is an image showing an electrode surface of a filter for a water treatment device according to an embodiment of the present disclosure; and

FIG. 13 is a graph showing the behavior of the ion removal rate depending on the number of operations of the filter for a water treatment device according to the embodiment of the present disclosure.

Reference will now be made in detail to embodiments of the present disclosure, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts, and redundant description thereof will be omitted. As used herein, the suffixes "module" and "unit" are added or used interchangeably to facilitate preparation of this specification and are not intended to suggest distinct meanings or functions. In describing embodiments disclosed in this specification, relevant well-known technologies may not be described in detail in order not to obscure the subject matter of the embodiments disclosed in this specification. In addition, it should be noted that the accompanying drawings are only for easy understanding of the embodiments disclosed in the present specification, and should not be construed as limiting the technical spirit disclosed in the present specification.

Furthermore, although the drawings are separately described for simplicity, embodiments implemented by combining at least two or more drawings are also within the scope of the present disclosure.

In addition, when an element such as a layer, region or module is described as being "on" another element, it is to be understood that the element may be directly on the other element or there may be an intermediate element between them.

The water treatment device according to an embodiment of the present disclosure may be any one of various water purification apparatuses, such as a water purifier or a water softener. In addition, the water treatment device according to the present disclosure may be a water purifier mounted in a washing machine, a dishwasher, a refrigerator, or the like.

The water treatment device according to an embodiment of the present disclosure may be embodied in various ways relating to discharge processes after electro-adsorption of ions and hard substances contained in raw water fed from the outside.

Hereinafter, a filter for a water treatment device according to an embodiment of the present disclosure will be described.

FIG. 1 is a partially cutaway perspective view illustrating a filter for a water treatment device according to an embodiment of the present disclosure. FIG. 1 illustrates a filter for a water treatment device of a deionization method such as capacitive deionization (CDI). The filter for such a water treatment device may be referred to as a "CDI module".

Referring to FIG. 1, the filter for a water treatment device includes a chamber 100 including a water inlet 110 through which water is supplied and a water outlet 120 through which water is discharged. FIG. 1 illustrates a partial cutaway view of the internal configuration of the chamber 100.

An electrode assembly 200 that is disposed so as to come into contact with the feed water fed through the water inlet 110 and includes a plurality of electrode units 201 (refer to FIG. 2) may be provided in the chamber 100.

A power connector 300 configured to supply power may be connected to the electrode assembly 200. One side of the electrode of the electrode assembly 200 may protrude from another side of the electrode assembly 200 so as to be connected thereto through the power connector 300.

As such, the electrode assembly 200 may be accommodated in the inner area of the chamber 100 and water (feed water) may be fed to the inner area of the chamber 100 from the outside through the water inlet 110.

In this case, the feed water may pass through the electrode assembly 200 and be discharged to the outside of the chamber 100 through the water outlet 120. In this process, ions contained in water may be removed by being adsorbed on the electrode assembly 200 while passing through the electrode assembly 200.

The chamber 100 may have a cuboid shape and may be divided into an upper portion 101 and a lower portion 102. The chamber 100 may be provided so as to avoid water leakage. For this purpose, an upper plate 103, a lower plate 104, a fastening means 130 such as a bolt configured to join the upper plate 103 to the lower plate 104, and a sealing member disposed therebetween may be provided.

As such, when the chamber 100 is divided into the upper portion 101 and the lower portion 102, the inner space of the chamber 100 is exposed to the outside, so a process of forming a stack of the electrode assembly 200 can be easily performed in the inner space.

In addition, when a problem occurs in the chamber 100, the upper portion 101 and the lower portion 102 are separated from each other, so inspection and repair can be easily performed.

The feed water supplied into the chamber 100 through the water inlet 110 may be supplied to the side surface of the electrode assembly 200. In this process, the feed water may be uniformly supplied to the entire side surface of the electrode assembly 200.

As such, ion exchange may be performed while water flows from the side surface of the electrode assembly 200 to the central part after uniform supply of water to the side surface of the electrode assembly 200. Then, the ion-exchanged water may be discharged to the outside through the water outlet 120 connected to the inside of the electrode assembly 200, for example, to the central part thereof.

FIG. 2 is a plan view illustrating an electrode unit of a filter for a water treatment device according to an embodiment of the present disclosure.

Referring to FIG. 2, an example of the electrode unit 201 as a unit constituting the electrode assembly 200 is shown. That is, a plurality of electrode units 201 may be stacked to form the electrode assembly 200.

The electrode unit 201 may include a plate-shaped electrode 211. The electrode 211 may include a current collector 211a and an activated carbon coating layer 211b formed by applying activated carbon to one or both sides of the current collector 211a. In addition, the current collector 211a may partially extend or be connected with a conductor to provide an electrode portion 211c. The power connector 300 may be connected to the electrode portion 211c. The detailed configuration and operation of the electrode unit 201 will be described in detail.

The electrode unit 201 removes the ions of the fed water by adsorption and then discharges the same.

An ion exchange membrane 212 may be further provided to further increase the rate of removal of ions by the electrode unit 201. In this case, the ion exchange membrane 212 may be formed to surround the electrode 211. Specifically, the ion exchange membrane 212 may seal the electrode 211 so as to prevent the feed water from penetrating into the same. That is, the ion exchange membrane 212 is larger than the electrode 211 and is thus firmly adhered to the outer periphery 211d of the electrode 211. Accordingly, the feed water may be blocked so as not to contact the electrode 211.

As described above, the structure in which the electrode 211 is surrounded with the ion exchange membrane 212 prevents penetration of ions into the electrode 211, thereby reducing the production of scale. Accordingly, the lifespan of the CDI module can be improved.

For example, the electrode 211 may be a cathode and the ion exchange membrane 212 may be a cation exchange membrane. As described above, an example of the structure in which the cathode 211 is surrounded with the cation exchange membrane 212 prevents the penetration of anions into the cathode 211, thereby reducing scale production.

Specifically, the structure in which the electrode 211 is surrounded with the ion exchange membrane 212 can block a bypass flow path through which raw water that is not filtered through the ion exchange membrane 211 flows between the ion exchange membrane 212 and the electrode 211.

At this time, only cations that have passed through the cation exchange membrane based on electrical attraction may pass through the cathode 211, whereas only the anions that pass through the anion exchange membrane may be present at the anode.

Accordingly, it is possible to minimize the production of scale and ancillary materials that may be caused by the presence of different ions on the electrode surface when the polarity of the electrode 211 is changed.

Scale production does not occur on the surface of the electrode 211, thus minimizing the reduction in the original area of the electrode 211, reducing the performance degradation of the CDI module and improving the durability of the CDI module. This process will be described in detail.

FIG. 3 is a cross-sectional view illustrating an electrode unit of a filter for a water treatment device according to an embodiment of the present disclosure.

FIG. 3 shows a cross-section of an electrode unit 202, illustrating the electrode unit 201 of FIG. 2 in more detail.

The electrode unit 202 may include a first electrode unit 210, a second electrode unit 220, and a spacer 230 disposed between the first electrode unit 210 and the second electrode unit 220.

Here, the first electrode unit 210 may include a first electrode 211 and a cation exchange membrane 212 configured to seal the first electrode 211. In addition, the second electrode unit 220 may include a second electrode 221 and an anion exchange membrane 222 configured to seal the second electrode 221.

In this case, the first electrode 211 may be a cathode and the second electrode 221 may be an anode. That is, the cation exchange membrane 212 may be formed to surround the cathode 211 and the anion exchange membrane 222 may be formed to surround the anode 221.

The first electrode 211 may include a current collector 211a and an activated carbon coating layer 211b formed by applying activated carbon to one or both sides of the current collector 211a. In addition, the current collector 211a may partially extend or be connected with a conductor to provide an electrode portion 211c. The power connector 300 may be connected to the electrode portion 211c.

Similarly, the second electrode 221 may include a current collector 221a and an activated carbon coating layer 221b formed by applying activated carbon to one or both sides of the current collector 221a. In addition, the current collector 221a may partially extend or be connected with a conductor to provide an electrode portion 211c. The power connector 300 may be connected to the electrode portion 211c.

The activated carbon coating layers 211b and 221b may be formed by applying a mixture of activated carbon particles, conductive polymer particles, and a binder to the surfaces of the

current collectors

211a and 221a.

As such, the activated carbon coating layers 211b and 221b may include activated carbon. Therefore, when impurities in raw water are adsorbed on the activated carbon coating layers 211b and 221b based on electrostatic attraction, the adsorbed impurities move through diffusion into pores called "macropores" in the surface of the activated carbon, and then are finally adsorbed in and thus removed from mesopores or micropores therein.

The activated carbon coating layers 211b and 221b may be formed on both surfaces of the

current collectors

211a and 221a. As described above, when the activated carbon coating layers 211b and 221b are formed on both surfaces of the

current collectors

211a and 221a, impurities contained in raw water can be adsorbed on both sides of the

current collectors

211a and 221a, and the impurity adsorption rate and adsorption ability can be improved.

A spacer 230 may be disposed between the two

electrode units

210 and 220. The spacer 230 can prevent a short circuit between the two

electrode units

210 and 220 while forming a gap between the two

electrode units

210 and 220. In addition, raw water may be purified while passing between the two

electrode units

210 and 220 through the spacer 230.

Accordingly, the spacer 230 is made of a water-permeable insulator material, thus preventing a short circuit between the

electrode units

210 and 220 and providing a flow path through which raw water being purified passes. For example, the spacer 230 may be made of a nylon material including a plurality of water flow paths.

As described above, the cation exchange membrane 212 may seal the first electrode 211 so as to prevent feed water from penetrating the first electrode 211 and the anion exchange membrane 222 may seal the second electrode 221 to prevent feed water from penetrating the second electrode 221.

Specifically, the cation exchange membrane 212 and the anion exchange membrane 222 may be formed to surround the entire area of the activated carbon coating layers 211b and 221b, respectively.

In addition, the cation exchange membrane 212 and the anion exchange membrane 222 may include

extension portions

213, 214, 223 and 224 that extend in the longitudinal direction of the first electrode 211 and the second electrode 221, respectively.

That is, the cation exchange membrane 212 may include a first extension portion 213 and a second extension portion 214 that extend in the longitudinal direction of the first electrode 211. In this case, the first extension portion 213 may be disposed at the opposite side of the electrode portion 211c that extends from the current collector 211a. Also, the second extension 214 may be disposed at the side of the electrode portion 211c extending from the current collector 211a. That is, the second extension portion 214 may be disposed at both sides of the electrode portion 211c to improve the airtightness of the connection portion between the current collector 211a and the electrode portion 211c.

Similarly, the anion exchange membrane 222 may include a first extension portion 223 and a second extension portion 224 that extend in the longitudinal direction of the second electrode 221. In this case, the first extension portion 223 may be disposed at the opposite side of the electrode portion 221c that extends from the current collector 221a. In addition, the second extension portion 224 may be disposed at the side of the electrode unit 221c that extends from the current collector 221a. That is, the second extension portion 224 may be disposed at both sides of the electrode unit 221c to improve the airtightness of the connection portion between the current collector 221a and the electrode unit 221c.

In addition, in order to further improve airtightness, sealing members 217 and 227 may be disposed at side ends of the

ion exchange membranes

212 and 222. The sealing members 217 and 227 may contain at least one of silicone, Teflon, PTFE, PTEE, rubber, EPDM, and polyester. That is, the sealing members 217 and 227 may be made of a compressible material to achieve a sealing effect.

The sealing members 217 and 227 may be divided at both side ends of the cation exchange membrane 212 or the anion exchange membrane 222. That is, based on the

electrodes

211 and 221, the sealing members 217 and 227 may be separately provided at both sides of the surfaces of the

electrodes

211 and 221. As such, the sealing members 217 and 227 may include first sealing

members

215 and 225 and

second sealing members

216 and 226. That is, two sealing members including the

first sealing members

215 and 225 and the

second sealing members

216 and 226 may be installed by being pressed against each other.

Meanwhile, the sealing members 217 and 227 may be installed in contact with the first extension portion 223 and the second extension portion 224, respectively. For example, the sealing members 217 and 227 may be divided at both sides of the first extension portion 223 and the second extension portion 224, respectively. That is, the first extension portion 223 and the second extension portion 224 are installed by pressing the first extension portion 223 and the second extension portion 224 in a pressing direction from both sides of the first extension portion 223 and the second extension portion 224, respectively, to improve airtightness. However, this is only an example and only one piece of sealing member may be provided.

FIG. 4 is a cross-sectional view illustrating an electrode assembly of a filter for a water treatment device according to an embodiment of the present disclosure.

Referring to FIG. 4, there is shown an example in which a plurality of

electrode units

202 and 203 form a stack with a spacer 231 interposed therebetween. Although two

electrode units

202 and 203 are shown in FIG. 4, more electrode units may form a stack.

In this case, each of the

electrode units

202 and 203 may include a first electrode unit 210, a second electrode unit 220, and a spacer 230 disposed between the first electrode unit 210 and the second electrode unit 220. Since each of the

electrode units

202 and 203 has the same configuration as described above, a duplicate description thereof will be omitted.

In addition, the first electrode units 210 may be connected to one another via a power connector 300 and the second electrode units 220 may be connected to one another via the power connector 300.

A power supply 310 may be connected to the power connector 300. Accordingly, the power supplied from the power supply 310 may be supplied to each of the first and

second electrode units

210 and 220 through the power connector 300.

Specifically, each of the

electrode units

202 and 203 may be connected to the power supply 310 through the power connector 300 such that an anode (+) and a cathode (-) are alternately formed.

FIG. 5 is a conceptual diagram illustrating the state in which water is purified through the filter for a water treatment device shown in FIG. 4, and FIG. 6 is a conceptual diagram illustrating the state in which the filter for a water treatment device shown in FIG. 4 is regenerated. Hereinafter, the operation of the filter for a water treatment device according to an embodiment of the present disclosure will be described with reference to FIGS. 5 and 6.

First, referring to FIG. 5, in the state in which an electrode 221 disposed on the left side of the drawing is positively charged and an electrode 211 disposed on the right side of the drawing is negatively charged, feed water is allowed to flow between the

electrodes

211 and 221. As a result, anions (-) contained in the feed water are adsorbed on the positively charged left electrode 221, whereas cations (+) contained in the feed water are adsorbed on the negatively charged right electrode 211.

As the anions (-) and cations (+) contained in the feed water are adsorbed and removed by this process, the feed water can be purified.

Conversely, in the state in which an electrode 211 (a first electrode) disposed on the right side of the drawing is positively charged and an electrode 221 (a second electrode) disposed on the left side of the drawing is negatively charged, feed water is allowed to flow between the

electrodes

211 and 221. As a result, anions (-) contained in the feed water are adsorbed on the positively charged right electrode 211, whereas cations (+) contained in the feed water are absorbed onto the negatively charged left electrode 221.

In this case, the feed water can easily pass between the

electrodes

211 and 221 through the water-permeable spacer 230 disposed between the

electrodes

211 and 221 to prevent a short circuit therebetween and secure a flow path.

However, if the number of ions adsorbed on the

electrodes

211 and 221 increases as adsorption continues, the

electrodes

211 and 221 can no longer adsorb ions or the ion adsorption capability thereof is remarkably reduced.

In this state, as shown in FIG. 6, it is necessary to detach the adsorbed ions from the

electrodes

211 and 221 to thereby regenerate the

electrodes

211 and 221.

As described above, methods for regenerating the

electrodes

211 and 221 include a method of cutting off current supply and a method of causing a current to flow in the direction opposite that of ion adsorption.

According to the present disclosure, when feed water (treatment water) 400 is supplied to the electrode assembly 200, the power supply 310 supplies current in one direction and adsorbs ions onto the

electrodes

211 and 221 to remove the ions from the water.

Then, when feed water (washing water) 400 is supplied to the electrode assembly 200, the power supply 310 supplies current in the direction opposite one direction above, and discharges the ions adsorbed on the

electrodes

211 and 221 into the water, to regenerate the

electrodes

211 and 221.

For example, in order to regenerate the

electrodes

211 and 221, as shown in FIG. 5, in the state in which anions (-) contained in raw water are adsorbed on the positively charged electrode 221 on the left side, and cations (+) contained in raw water are adsorbed on the negatively charged electrode 211 on the right side, the electrode 221 on the left side of the drawing is charged with a cathode, and the electrode 211 on the right side of the drawing is charged with an anode by changing the flow of current, as shown in FIG. 6.

Then, the anions (-) adsorbed on the left electrode 221 in the water purification process are separated from the negatively charged left electrode 221, and the cations (+) adsorbed on the right electrode 211 in the water purification process are separated from the positively charged right electrode 211.

In this process, the cations (+) and anions (-) separated from the

electrodes

211 and 221 on both sides are discharged to the outside along with the washing water 400.

When the ions adsorbed on the

electrodes

211 and 221 are removed through the process of cleaning the

electrodes

211 and 221, the ion removal ability of the electrode assembly 200 is regenerated, so the ion removal ability can be maintained constant.

When the electrode assembly 200 is driven in this way, ions are quickly removed from water, so the hardness of water is lowered and thus the water can be softened.

FIG. 7 is a flowchart illustrating a process of manufacturing an electrode assembly of a filter for a water treatment device according to an embodiment of the present disclosure. FIGS. 8 and 9 are cross-sectional schematic views illustrating a part of the process illustrated in FIG. 7.

FIGS. 7 to 9 illustrate a process of manufacturing a first electrode unit 210 including a first electrode 211. However, this may apply to a process of manufacturing a second electrode unit 220 including a second electrode 221.

Referring to FIGS. 7 and 8, in order to manufacture the electrode assembly 200, first, a first electrode 211 and a cation exchange membrane 212 may be prepared by being blanked to an appropriate size (S10).

At this time, the cation exchange membrane 212 may be prepared as two separate portions. That is, in the subsequent joining process, the cation exchange membrane 212 may be bonded to both surfaces of the first electrode 211.

Then, a sealing member 217 to be located outside the cation exchange membrane 212 may be prepared by being blanked to an appropriate size (S20). In this case, the sealing member 217 may be prepared in a rectangular band shape. In addition, the sealing member 217 may be blanked so as to have a size larger than that of the cation exchange membrane 217.

Then, the first electrode 211, the cation exchange membrane 212, and the sealing member 217 are matched and fused to produce a first electrode unit 210 (S30).

In the subsequent fusion process, the cation exchange membrane 212 may be joined to both surfaces of the first electrode 211. In this process, the cation exchange membrane 212 may form a first extension portion 213 and a second extension portion 214 at the end side of the first electrode 211. The first extension portion 213 and the second extension portion 214 may effectively seal the first electrode 211.

In addition, the sealing member 217 bonded to the first extension portion 213 and the second extension portion 214 can more effectively seal the first electrode 211.

Then, the second electrode unit 220 may be produced in the same manner as in the first electrode unit. The plurality of first electrode units 210 and second electrode units 220 produced as described above may be bonded to

spacers

230 and 231 to form a stack (S40).

As mentioned above, the sealing members 217 and 227 may contain at least one of silicone, Teflon, PTFE, PTEE, rubber, EPDM, and polyester. That is, the sealing members 217 and 227 may be made of a compressible material for a sealing effect.

These sealing members 217 and 227 may be divided at both side ends of the cation exchange membrane 212 or the anion exchange membrane 222. That is, two sealing members including the

first sealing members

215 and 225 and the

second sealing members

216 and 226 may be installed by being pressed against each other.

For example, the

first sealing members

215 and 225 may be made of a silicone material, and the

second sealing members

216 and 226 may be made of a PTFE material.

The sealing members 217 and 227 may be disposed so as to come into contact with the first extension portion 223 and the second extension portion 224, respectively.

In this way, the first extension portion 223 and the second extension portion 224 are installed by pressing the first extension portion 223 and the second extension portion 224 in a pressing direction from both sides of the first extension portion 223 and the second extension portion 224, respectively, to improve airtightness.

Accordingly, the first extension portion 223 and the second extension portion 224 are formed by pressing in the state in which the total thickness of the first extension portion 223 and the second extension portion 224 is approximately 10 to 15% greater than the total thickness of the structure in which the cation exchange membrane 212 is fused to both sides of the first electrode 211, so the total thickness of the first extension portion 223 and the second extension portion 224 becomes the same as the thickness of the structure in which the cation exchange membrane 212 is fused to both sides of the first electrode 211.

FIG. 10 is a schematic diagram illustrating the state in which a bypass flow path is formed in an electrode assembly of a conventional filter for a water treatment device as a comparative example. FIG. 11 is an image showing an electrode surface of the conventional filter for a water treatment device. FIG. 12 is an image showing an electrode surface of a filter for a water treatment device according to an embodiment of the present disclosure.

Referring to FIG. 10, under ideal conditions during the adsorption operation by the water treatment device (CDI module), because the cation exchange membrane 32 is positioned on the cathode electrode 31, only cations such as calcium ions (Ca²⁺) and magnesium ions (Mg²⁺) can be adsorbed on a cathode 31 without a chemical reaction.

However, in practice, a bypass flow path B may be formed between the cation exchange membrane 32 and the cathode 31. Feed water normally moves along the path a, but raw water (feed water) may be fed through the bypass flow path B as indicated by the arrow b.

Anions such as carbonate ions (CO₃ ^2-) are present in the feed water. Among the anions, carbonate ions (CO₃ ^2-) react with calcium ions (Ca²⁺) that have passed through the cation exchange membrane based on electrical attraction to produce calcium carbonate (CaCO₃) which adheres in the form of scale to the surface of the cathode.

This phenomenon may occur between the anode 21 and the anion exchange membrane 22. That is, the bypass flow path A may be generated between the anode 21 and the anion exchange membrane 22, thus allowing formation of scale on the anode 21.

The cation exchange membrane 32 allows permeation of cations (Ca²⁺, Mg²⁺, etc.), which are materials causing scale formation, but does not allow permeation of anions (Cl^-, CO₃ ^2-, SO₄ ^2- , HCO^3-, etc.).

An ion exchange membrane can be formed by performing coating or using a membrane-type film when applying an ion exchange material to a CDI module. In general, in order to coat an electrode with an ion exchange membrane, an organic solvent may be mainly used to dissolve raw materials in a single solution. However, there may be problems in that the organic solvent is harmful to the human body and is not completely removed even upon drying after coating due to the non-standardized characteristics of carbon electrodes.

In addition, in general, various ionic substances exist in water, and in particular, scale-inducing substances such as Ca²⁺ and Mg²⁺ may react with anions such as CO₃ ^2- or HCO^3- to form scale (CaCO₃). This causes a decrease in the active area of the carbon electrode, and the decrease in the active area may decrease the ion adsorption capacity of the CDI module.

FIG. 11 illustrates the state in which the scale generated by the movement of feed water along the bypass flow paths A and B is formed.

FIG. 11 illustrates the surfaces of the activated carbon coating layers 211b and 221b. The activated carbon coating layers 211b and 221b contain a material containing carbon (activated carbon) and are thus entirely black before the CDI module is operated. However, as the number of operations of the CDI module increases, scale forms on the surfaces of the activated carbon coating layers 211b and 221b, so that the area of the black portion becomes narrower.

As can be seen from FIG. 11, scale is formed in a significant portion of the area of the activated carbon coating layers 211b and 221b, and gray or white portions are shown. In particular, it can be seen that scale is intensively formed in the upper right and lower left portions of the total area.

However, when the

electrode units

210 and 220 according to the embodiment of the present disclosure described above are applied, the bypass flow path is blocked, thereby reducing scale formation on the electrode. Accordingly, the lifespan of the CDI module can be improved.

FIG. 12 illustrates the electrode surface of the filter for a water treatment device according to an embodiment of the present disclosure, and illustrates the state in which the electrode is operated for the same amount of time as in the case of FIG. 11. Comparing FIG. 11 with FIG. 12, it can be seen that when the CDI module is operated for the same amount of time (for the same number of operations), the formation of scale is greatly reduced when the embodiment of the present disclosure is applied.

That is, as can be seen from FIG. 12, most areas of the activated carbon coating layers 211b and 221b remained black. Accordingly, comparing FIG. 11 with FIG. 12, it can be seen that the white or gray portion in which the scale is formed in FIG. 12 is greatly reduced compared to FIG. 11.

FIG. 13 is a graph showing the behavior of the ion removal rate according to the number of operations of the filter for a water treatment device according to an embodiment of the present disclosure.

FIG. 13 shows the behavior of the ion removal rate of the embodiment of the present disclosure and the related art to which the features of the embodiment of the present disclosure are not applied.

As described above, the ion removal rate may decrease depending on the number of operations due to scale or ion adsorption.

FIG. 13 shows the ion removal rate when a smaller stack (including 20 electrode units) is applied. It can be seen from FIG. 13 that the effect is not significantly different, but the removal rate is improved compared to the case of the related art.

In practice, when a stack is manufactured using a large number of electrode units, the ion removal rate will be significantly improved compared to the related art.

As described above, according to an embodiment of the present disclosure, a structure in which an electrode is surrounded with an ion exchange membrane can reduce scale formation. For example, a structure in which a cathode is surrounded with a cation exchange membrane can block the flow of anions to the cathode, thereby reducing scale production. Accordingly, the lifespan of the CDI module can be improved.

In this case, only cations that have passed through the cation exchange membrane based on electrical attraction pass through the cathode, whereas only the anions that pass through the anion exchange membrane may be present at the anode. Accordingly, it is possible to minimize the production of scale and ancillary materials that may occur due to the presence of different ions on the electrode surfaces when the polarity of the electrodes is changed.

The above description is merely illustrative of the technical spirit of the present disclosure. It will be apparent to those skilled in the art that various modifications and variations can be made in the present disclosure without departing from the spirit and scope of the disclosure.

Therefore, the embodiments disclosed in the present disclosure are merely illustrative of the technical spirit of the present disclosure. The scope of the technical spirit of the present disclosure is not limited by these embodiments.

The scope of the present disclosure should be construed by the appended claims, and all technical ideas within the scope equivalent thereto should be construed as being within the scope of the present disclosure.

According to the present disclosure, a filter for a water treatment device that is applicable to water purifiers is provided.

Claims

A filter for a water treatment device comprising:

a chamber comprising a water inlet and a water outlet;

an electrode assembly disposed in the chamber so as to come into contact with feed water fed through the water inlet, the electrode assembly comprising a plurality of electrode units; and

a power connector configured to supply power to the electrode assembly,

wherein each electrode unit comprises:

a plate-shaped electrode; and

an ion exchange membrane configured to filter ions contained in the feed water and block contact between the feed water and the electrode.
The filter of claim 1, wherein the ion exchange membrane seals the electrode so as to prevent the feed water from penetrating into the electrode.
The filter of claim 1, wherein the electrode comprises:

a current collector; and

an activated carbon coating layer disposed on at least one surface of the current collector.
The filter of claim 3, wherein the ion exchange membrane surrounds an entire area of the activated carbon coating layer.
The filter of claim 3, wherein the ion exchange membrane comprises an extension portion that extends toward a side end of the current collector.
The filter of claim 1, further comprising a sealing member disposed at a side end of the ion exchange membrane.
The filter of claim 6, wherein the sealing member comprises at least one of silicone, Teflon, PTFE, PTEE, rubber, EPDM, and polyester.
The filter of claim 6, wherein the sealing member is divided into two portions at both sides of the extension portion.
The filter of claim 8, wherein the two divided sealing members are provided so as to be pressed against each other.
A filter for a water treatment device comprising:

a chamber comprising a water inlet and a water outlet;

an electrode assembly disposed in the chamber so as to come into contact with feed water fed through the water inlet, the electrode assembly comprising a first electrode unit, a second electrode unit, and a spacer disposed between the first electrode unit and the second electrode unit; and

a power connector configured to supply power to the electrode assembly,

wherein the first electrode unit comprises:

a first electrode; and

a cation exchange membrane sealing the first electrode, and

the second electrode unit comprises:

a second electrode; and

an anion exchange membrane sealing the second electrode.
The filter of claim 10, wherein the cation exchange membrane seals the first electrode so as to prevent the feed water from penetrating into the first electrode, and the anion exchange membrane seals the second electrode to prevent the feed water from penetrating into the second electrode.
The filter of claim 10, wherein the cation exchange membrane and the anion exchange membrane comprise extension portions that extend in a longitudinal direction of the first electrode and the second electrode, respectively.
The filter of claim 10, further comprising a sealing member disposed at a side end of the cation exchange membrane or the anion exchange membrane.
The filter of claim 13, wherein the sealing member is divided into two portions at both side ends of the cation exchange membrane or the anion exchange membrane.
The filter of claim 14, wherein the two divided sealing members are provided so as to be pressed against each other.