WO2022102884A1 - Deionization device - Google Patents

Abstract

The present invention provides a deionization device comprising: a treated water flow path for providing a path through which seawater, saline water or wastewater enters, and treated water which has been treated is discharged; an ion adsorption part disposed on one side of the treated water flow path, and comprising an ion adsorbent; a first ion-exchange membrane disposed on the other side of the treated water flow path; a second ion-exchange membrane disposed between the treated water flow path and the ion adsorption part; a third ion-exchange membrane disposed on one side of the ion adsorption part, and enabling the passing through of ions having the same electric charge as ions which have passed through the first ion-exchange membrane; a first flow path disposed on one side of the first ion-exchange membrane; a second flow path disposed on one side of the third ion-exchange membrane; a pair of electrodes disposed in the first flow path and the second flow path, respectively; and an electrolyte flowing in the first flow path and the second flow path, and comprising a redox reaction material.

Description

desalination device

The present invention relates to a desalting device, and more particularly, to a desalting device having an improved desalting capacity.

In the world, the value of water as a resource is increasing due to the deepening of drought caused by global warming, the depletion of groundwater, the progress of desertification, and the increase in the use of living and industrial water due to population growth and industrialization. Recycling is emerging as a new issue. In addition, as interest in the manufacture of industrial ultrapure water increases, and the demand for clean water to eat and wash in daily life increases, research on the development of high-efficiency ion removal devices is being actively conducted.

In addition, when hard water is used as industrial water and household water, the detergent does not dissolve well, but also causes industrial and sanitary problems due to the formation of scale by divalent cations (Ca2+, Mg2+, etc.). Therefore, in order to reduce the damage caused by the use of hard water, the softening process is essential, and technological development for this is actively underway. In addition, removal of radioactive Cs+ ions present in water and recovery of Li+ ions are recognized as important in the environment and industrial distribution.

Currently, the technology to remove ionic substances mainly uses the evaporation method, the reverse osmosis membrane method, and the ion exchange resin method. The evaporation method and the reverse osmosis membrane method have operating costs and operational problems due to high energy consumption, The exchange resin method has the disadvantage of creating secondary pollutants because it uses an excessive amount of acid (Acid) or salt (NaCl) during regeneration.

Research is underway in many countries around the world to compensate for the shortcomings of the existing dissolved ion removal technologies and to develop a new low energy consumption type ion removal technology. There is a Capacitive Deionization (CDI) technology.

CDI technology, an electro-adsorption type ion removal technology, consumes less energy than other methods, and unlike the existing ion removal technology, it does not require cleaning with chemicals, so it is an environmentally friendly new ion removal technology that does not cause secondary pollution. Due to the advantage of simplicity, research is being actively conducted as a next-generation dissolved ion removal technology.

The first CDI process research was conducted in the 1960s by researchers at the University of Oklahoma in the US using a porous activated carbon electrode to study seawater desalination. However, the development was not possible due to the continuous process difficulties due to the deterioration of the electrode, which is a key factor, but research was conducted at LLNL (Lawrence Livermore National Laboratory) in the United States in the mid-1990s, such as developing a CDI process using carbon airgel electrodes. In addition, research on the development of a CDI process using activated carbon fibers and carbon nanotubes as electrode active materials has been conducted.

CDI is a technology that reversibly removes ions from raw water using electrochemical adsorption/desorption. This process removes ions in the raw water by storing the ions in a double layer on the electrode surface when an electric potential is applied. However, the capacitive desalination process inevitably wastes some of the charge required for ion adsorption. This is because, when the electric double layer is formed, power is consumed to repel the charged ions (ions having the same potential as the electrode potential) existing on the electrode surface. To overcome these limitations, membrane capacitive deionization (MCDI) systems have emerged. MCDI relieves 'coin charge ion repulsion' by applying an ion exchange membrane, and dramatically improves the desalination performance and charge efficiency.

Ion-selective membranes located in front of both electrodes (cation exchange membrane on cathode and anion exchange membrane on anode) saved the charge consumed by the same charge ions. The MCDI system has been actively developed such as low-concentration operation, constant current operation, and energy recovery.

The development of ion exchange materials applied to MCDI proceeded in two directions.

First, the material of the ion exchange membrane was developed. As an example of such an ion exchange membrane development, NaSS-MAA-MMA copolymer was applied as a cation exchange membrane and 4-vinylbenzylchloride/styrene/ethylmethacrylate was applied as an anion exchange membrane. In addition, cross-linked quaternised polyvinyl alcohol was suggested as AEM, and the desalting capacity was improved by about 2 times. In addition to the ion exchange membrane, studies showing performance improvement through the application of an ion exchange material for coating to the electrode have also been reported.

Second, it was developed in the direction of coating the electrode with an ion exchange material. As a development example of a method for coating such an ion exchange material on an electrode, as a cation exchange resin, polyvinyl alcohol/sulfosuccinic acid was coated on the negative electrode to dramatically improve the desalination performance. In addition, by spraying bromomethylated poly(2,6-dimethyl-1,4-phenyleneoxide) (BPPO) treated with sulfuric acid and amine on the positive/negative electrodes, the coating of the ion exchange material was simply successful. Nie et al. achieved good regenerationability (30 cycles) by directly coating the electrode with polyacrylic acid as a cation exchange resin using the electrodeposition method.

As such, when using a carbon electrode, it has a large surface area and has an excellent advantage in relatively stable capacity characteristics in aqueous solution, but there is a disadvantage in that the resistance of carbon itself is not small, and the surface characteristic is hydrophobic, so it is not friendly with water. It also tends to be a bit slow in terms of speed.

Therefore, the development of a desalting process having excellent speed characteristics while efficiently desalting has been required.

<Prior art literature>

Patent Document 1: Republic of Korea Patent No. 1237258

Patent Document 2: Republic of Korea Patent No. 1410642

Patent Document 3: Republic of Korea Patent Publication No. 2012-0058228

In order to solve the above problems, an object of the present invention is to provide a desalting apparatus capable of improving the desalting capacity in a capacitive desalting process.

On the other hand, the technical problems to be achieved in the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned are clearly to those of ordinary skill in the art to which the present invention belongs from the description below. can be understood

In order to achieve the above object, the present invention provides a treatment water flow path that provides a path through which seawater, salt water or wastewater is introduced and the treated water is discharged; an ion adsorption unit disposed on the other side of the treated water flow path and including an ion adsorbent; a first ion exchange membrane disposed on one side of the treated water passage; a second ion exchange membrane disposed between the treated water passage and the ion adsorption unit; a third ion exchange membrane disposed on the other side of the ion adsorption unit and allowing ions having the same charge as the ions passed through the first ion exchange membrane to pass therethrough; a first flow path disposed on one side of the first ion exchange membrane; a second flow path disposed on the other side of the third ion exchange membrane; a pair of electrodes respectively disposed in the first flow path and the second flow path; and an electrolyte solution flowing in the first flow path and the second flow path, and including a redox reaction material; may include

The first ion exchange membrane and the third ion exchange membrane may be an anion exchange membrane, and the second exchange membrane may be a cation exchange membrane.

The ion adsorbent may selectively adsorb cations.

Anions may be introduced from the seawater, salt water or wastewater in the first flow path, and anions may be discharged to the ion adsorption unit in the second flow path.

Anions may be introduced from the seawater, salt water or wastewater in the first flow path, and anions may be discharged to the ion adsorption unit in the second flow path.

The ion adsorbent may selectively adsorb cations.

The desalination apparatus according to the present invention includes a redox reaction material in the electrolytic solution flowing to the electrode, thereby improving the desalting capacity in the capacitive desalting process.

On the other hand, the effects obtainable in the present invention are not limited to the above-mentioned effects, and other effects not mentioned will be clearly understood by those of ordinary skill in the art to which the present invention belongs from the description below. will be able

1 is an exemplary view schematically showing a desalination apparatus according to an embodiment of the present invention,

2 is an exemplary view schematically showing a desalination apparatus according to another embodiment of the present invention,

3 is a graph showing changes in conductivity and pH of treated water during a desalting process through a desalting device according to an embodiment of the present invention;

4 and 5 are graphs showing the change in adsorption concentration according to the adsorbent during the regeneration process through the desalting device according to an embodiment of the present invention.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. First, it should be noted that in the drawings, the same components or parts are denoted by the same reference numerals as much as possible. In describing the present invention, detailed descriptions of related well-known functions or configurations are omitted so as not to obscure the gist of the present invention.

As used herein, the terms "about," "substantially," and the like are used in a sense at or close to the numerical value when the manufacturing and material tolerances inherent in the stated meaning are presented, and serve to enhance the understanding of the present invention. To help, precise or absolute figures are used to prevent unfair use by unconscionable infringers of the stated disclosure.

1 is an exemplary diagram schematically illustrating a desalting apparatus according to an embodiment of the present invention.

The present invention is characterized in that the redox reaction material is included in the electrolytic solution flowing to the electrode in the desalting device.

Referring to FIG. 1 , the desalination apparatus 100 according to an embodiment of the present invention includes a treated water flow path 11 that continuously provides a path through which seawater, salt water or wastewater is introduced and treated treated water is discharged, and the treatment The ion adsorption unit 40 disposed on the other side of the water channel 11 and including the ion adsorbent 41 , the first ion exchange membrane 21 disposed on one side of the treated water channel 11 , and the treated water channel 11 . ) and the second ion exchange membrane 22 disposed between the ion adsorption unit 40, disposed on the other side of the ion adsorption unit 40, ions having the same charge as the ions passed by the first ion exchange membrane 21 A third ion exchange membrane 23, a first flow path 31 disposed on one side of the first ion exchange membrane 21, a second flow path 32 disposed on the other side of the third ion exchange membrane 23, a first flow path ( 31) and a pair of electrodes 51 and 52 disposed in the second flow path 32, respectively, and an electrolyte solution flowing in the first flow path 31 and the second flow path 32 and including a redox reaction material ( 30) is included.

The treated water flow path 11 may provide a path through which seawater, salt water, or wastewater may be introduced and the treated treated water 10 may be discharged.

Here, the seawater, brine or wastewater may include desalting cations and anions.

The first ion exchange membrane 21 is disposed on one side of the treated water flow path 11 and the second ion exchange membrane 22 is disposed on the other side, so that cations and anions in seawater, brine or wastewater can be exchanged. In addition, the third ion exchange membrane 23 is disposed on the other side of the ion adsorption unit 40 , so that cations or anions in the electrolyte 30 may permeate toward the ion adsorption unit 40 .

Here, the first ion exchange membrane 21 and the third ion exchange membrane 23 may exhibit selective permeability to ions of the same charge, and the second ion exchange membrane 22 is the first ion exchange membrane 21 and the third ion It is possible to exhibit selective permeability to ions having a different charge from that of the exchange membrane 23 .

On the other hand, in the desalting apparatus 100 according to an embodiment of the present invention, the first ion exchange membrane 21 and the third ion exchange membrane 23 are composed of an anion exchange membrane to exhibit selective permeability to anions, and a second ion exchange membrane ( 22) is composed of a cation exchange membrane and can exhibit selective permeability to cations.

2 is an exemplary view schematically showing a desalination apparatus according to another embodiment of the present invention.

On the other hand, referring to FIG. 2 , in the desalting apparatus 200 according to another embodiment of the present invention, the first ion exchange membrane 221 and the third ion exchange membrane 223 are composed of a cation exchange membrane to exhibit selective permeability to cations. , the second ion exchange membrane 222 may be configured as an anion exchange membrane to exhibit selective permeability to anions.

Here, any of the ion exchange membranes 21 and 22 and the electrodes 51 and 52 that have been used in conventional capacitive electrodes (battery, storage battery, etc.) can be used, and a person of ordinary skill in the art It can be appropriately selected and used according to the purpose and conditions of its use.

The first ion exchange membrane 21 and the second ion exchange membrane 22 are micropore insulating membranes, and may be ion exchange (conductive) membranes. The first ion exchange membrane 21 and the second ion exchange membrane 22 are installed for electrophysical separation. The micropore insulating separator is capable of only ion movement, and the ion exchange (conductive) membrane is a cation or Only anions can be selectively moved.

The electrodes 51 and 52 may include a first electrode 51 disposed adjacent to the first ion exchange membrane 21 and a second electrode 52 disposed adjacent to the second ion exchange membrane 22 .

On the other hand, since the amount of ions adsorbed to the electrodes 51 and 52 is determined according to the capacitance of the used electrode, a porous carbon electrode having a large specific surface area may be used in the present invention.

The first electrode 51 is disposed in the first flow path 31 disposed on one side of the first ion exchange membrane 21 , and the second electrode 52 is a second electrode disposed on the other side of the third ion exchange membrane 23 . It may be disposed in the flow path 32 .

Here, the first electrode 51 may be disposed to be spaced apart from the first ion exchange membrane 21 , and the second electrode 52 may be disposed to be spaced apart from the third ion exchange membrane 23 .

Here, although not shown, the positive electrode active material may be coated on the first electrode 51 , and the negative electrode active material may be coated on the second electrode 52 .

It is preferable that the first flow path 31 and the second flow path 32 communicate with each other, and the electrolyte 30 introduced into the first flow path 31 is desalted through the first ion exchange membrane 21 after performing a desalting process. , may be discharged toward the second flow path 32 . Here, upper ends of the first passage 31 and the second passage 32 may communicate through a tube or the like.

In addition, the electrolyte 30 introduced into the second flow path 32 may be discharged to the first flow path 31 after performing a regeneration process through the third ion exchange membrane 23 .

Here, the lower ends of the first passage 31 and the second passage 32 may communicate through a tube or the like, and the flow of the electrolyte 30 may be controlled through a storage container disposed in the middle.

The electrolyte 30 may include a redox reaction material.

Here, the redox material of the electrolyte solution 30 may include a ferrocyanide compound.

In one example, the redox material of the electrolyte 30 may be selected as Na ₄ Fe(CN) ₆ .

On the other hand, the redox reaction material of the electrolyte 30 may be subjected to a redox reaction as shown in the following [reaction formula].

[reaction formula]

The first ion exchange membrane 21 may selectively permeate cations, and the second ion exchange membrane 22 may selectively permeate anions.

In addition, when the generated potential difference supplied from the outside, for example, a potential difference in the range of 0.5 to 2.0v is applied to the first electrode 51 and the second electrode 52 , the electrode is charged with a certain amount of charge.

When brine water containing ions is passed through the charged electrodes 51 and 52, first, ions having an opposite charge to the charged electrode move to the respective electrodes 51 and 52 by electrostatic force and are desalted. The water becomes pure water (treated water) 40 from which ions are removed.

Here, the negative ions moving to the first electrode 51 side (one side) are adsorbed on the surface of the first electrode 51 , and the positive ions moving to the second electrode 52 side (the other side) are absorbed into the ion adsorption unit 40 . It may be introduced and adsorbed by the ion adsorbent 41 .

In addition, the electrolyte 30 flows in the first passage 31 and the second passage 32 in which the electrodes 51 and 52 are disposed, and the redox reaction material of the electrolyte 30 is a voltage applied to the electrodes. Due to this, a redox reaction is performed, and at this time, anions are introduced into the electrolyte 30 through the first ion exchange membrane 21 to balance the charge of the electrolyte, and cations are adsorbed through the second ion exchange membrane 22 . It flows into the part 40 to increase the desalination performance of the treated water flow path 11 .

For example, the redox material in the first flow path 31 may perform an oxidation reaction due to the + voltage applied to the first electrode 51 , and the redox reaction material in the ion adsorption unit 40 is the second electrode A reduction reaction can be carried out due to the -voltage applied to (52).

In addition, in the treated water flow path 11 , cations may be introduced into the ion adsorption unit 40 through the second ion exchange membrane 22 to balance charges.

That is, the desalination apparatus according to an embodiment of the present invention can simultaneously utilize the ion treatment mechanism according to the capacitance of the electrode and the ion treatment mechanism according to the electron transfer reaction through the redox couple, so that the desalination performance can improve

On the other hand, relatively excessive anions are present at the inlet ends of the first flow path 31 and the second flow path 31 , and positive ions introduced from the treated water flow path 11 are excessively present in the ion adsorption unit 40 . , between the second flow path 31 and the ion adsorption unit 40 , the anions of the second flow path 31 may be introduced into the ion adsorption unit 40 through the third ion exchange membrane 23 to balance charges. .

Through this, the electrolyte 30 of the second flow path 31 may be regenerated in a state in which negative ions are discharged. That is, without performing a separate regeneration process, the electrolyte 30 can discharge the absorbed negative ions, so the electrolyte 30 can be recycled and the desalination process can be performed in a continuous process, and the electrodes 51 and 52 . It is possible to prevent the adsorption of more ions than necessary.

On the other hand, the ion adsorbent 40 may be composed of a plurality of ion adsorbents 41 dispersed in an aqueous ion medium. The ion adsorbent 41 may adsorb cations flowing in from the treated water 10 of the treated water flow path 11 .

Here, the ion adsorbent 41 is formed of a highly selective adsorbent capable of adsorbing only specific metal ions. For example, when the ion to be adsorbed is gold ion, the ion adsorbent 41 is Glutaraldehyde crosslinked chitosan bead or Mesoporous silica- 48-crosslinked with tannic acid, when the ion to be adsorbed is silver ion, the ion adsorbent 41 may be composed of graphitic carbon nitride, and when the ion to be adsorbed is lithium ion, the ion adsorbent 41 may be composed of lithium manganese oxide.

However, the ion adsorbent 41 may be implemented in various embodiments, and the present invention is not limited thereto.

Here, through a subsequent process, the ions adsorbed by the ion adsorbent 41 may be separated, and a required component may be easily recovered through this. That is, noble metals, etc. present in the wastewater 10 can be easily recovered.

Meanwhile, in the present invention, the ion adsorption unit 40 may be disposed between the treated water flow path 11 and the second flow path 32 in the form of accommodating the ion medium and the ion adsorbent 41 in a container having an internal space. In addition, the medium containing the ion adsorbent 41 may constitute an ion adsorption flow path having a flow.

<Measurement result>

Hereinafter, with reference to FIGS. 3 to 5, the desalination performance according to the desalination apparatus according to an embodiment of the present invention will be described.

3 is a graph showing changes in conductivity and pH of treated water during a desalting process through a desalting device according to an embodiment of the present invention, and FIGS. 4 and 5 are regeneration through a desalting device according to an embodiment of the present invention It is a graph showing the change in adsorption concentration according to the adsorbent during the process.

Example

In the embodiment, as described above, the desalination device is configured, and the conductivity and pH of the treated water are measured by varying the voltage applied to the electrode, and the change is shown in a graph as shown in FIG. 3 .

Referring to FIG. 3 , it can be confirmed that the electrical conductivity and pH are constant without change even when each voltage and process time are changed.

Here, FIG. 2 is for measuring the change in pH due to H ⁺ and OH ⁻ , and is a graph showing the measurement of the pH of the treated water. In general, pH is an indicator that can confirm the adsorption/desorption reaction of ions in the solution or the oxidation/reduction reaction by a certain chemical species in the cell when an electrical force is applied to the electrode. should be

In the desalination apparatus according to an embodiment of the present invention, it was confirmed that the range of change with respect to the pH, which had a fairly high efficiency, was not large. The range of change in pH is about ±0.1, confirming that the force applied to the electrode is more favorable to the adsorption/desorption reaction of ions. In addition, it can be confirmed that the treated water is continuously desalted as the conductivity change graph continuously points to the - index. In addition, it was found that the amount of ions that can be removed increases as the voltage applied to the system increases. That is, the desalting performance can be maintained even when the desalting process is continuously performed in the desalting apparatus according to an embodiment of the present invention.

In addition, referring to FIGS. 4 and 5 , it can be seen that lithium ions and sodium ions are efficiently concentrated over time. In the case of lithium, it was found that it was concentrated to 37 mM, and in the case of sodium, it was possible to be concentrated up to 51 mM higher than this. The concentrated ions can easily concentrate the ion component required by changing the type of the ion adsorbent used, and can be post-processed to recover the selective ion component for each adsorbent.

The present invention described above is not limited by the above-described embodiments and the accompanying drawings, and it is common in the technical field to which the present invention pertains that various substitutions, modifications, and changes are possible without departing from the technical spirit of the present invention. It will be clear to those who have knowledge.

Claims (7)

1. a treated water flow path providing a path through which seawater, salt water, or wastewater is introduced and the treated treated water is discharged;

   an ion adsorption unit disposed on the other side of the treated water flow path and including an ion adsorbent;

   a first ion exchange membrane disposed on one side of the treated water passage;

   a second ion exchange membrane disposed between the treated water passage and the ion adsorption unit;

   a third ion exchange membrane disposed on the other side of the ion adsorption unit and allowing ions having the same charge as the ions passed through the first ion exchange membrane to pass therethrough;

   a first flow path disposed on one side of the first ion exchange membrane;

   a second flow path disposed on the other side of the third ion exchange membrane;

   a pair of electrodes respectively disposed in the first flow path and the second flow path; and

   It flows in the first flow path and the second flow path, and contains a redox reaction material.

   electrolyte; A desalination device comprising a.
2. According to claim 1,

   The first ion exchange membrane and the third ion exchange membrane are anion exchange membranes,

   The second exchange membrane is a cation exchange membrane desalination device.
3. 3. The method of claim 2,

   The ion adsorbent is a desalting device for selectively adsorbing cations.
4. 4. The method of claim 3,

   In the first flow path, anions are introduced from the seawater, salt water or wastewater,

   A desalting device for discharging anions to the ion adsorption unit in the second flow path.
5. According to claim 1,

   In the first flow path, anions are introduced from the seawater, salt water or wastewater,

   A desalting device for discharging anions to the ion adsorption unit in the second flow path.
6. 6. The method of claim 5,

   The ion adsorbent is a desalting device for selectively adsorbing cations.
7. According to claim 1,

   The first ion exchange membrane and the third ion exchange membrane are cation exchange membranes,

   The second exchange membrane is an anion exchange membrane.

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