JP2003094064A - Electrodeionization equipment - Google Patents

Abstract

(57) [Problem] To provide a long-term operation by preventing performance degradation of an ion conductive substance filled in an electrode chamber of an electrodeionization apparatus. An anode chamber having an anode and a cathode are provided.
2 and a concentration chamber 15 and a desalination chamber alternately formed by alternately arranging a plurality of anion exchange membranes 13 and cation exchange membranes 14 between the anode chamber 17 and the cathode chamber 18. An electrodeionization device including a chamber 16. The anode compartment 17 and the cathode compartment 18 are filled with an ion conductive substance, water or pure water from which anions have been removed is passed through the anode compartment 17, and water or pure water from which cations have been removed pass through the cathode compartment 18. Water is passed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrodeionization device, and more particularly to an electrodeionization device having an electrode chamber (anode chamber and cathode chamber) filled with an ion conductive substance to improve electrical efficiency. In the device, the present invention relates to an electric deionization device capable of long-term operation by preventing performance deterioration of an ion conductive substance filled in an electrode chamber.

[0002]

2. Description of the Related Art Conventionally, semiconductor manufacturing plants, liquid crystal manufacturing plants,
As shown in FIG. 2, electrodes (anode 11, cathode 12) are used for the production of deionized water used in various industries such as the pharmaceutical industry, the food industry, the electric power industry, or for consumer or research facilities.
A plurality of anion exchange membranes (A membranes) 13 and a plurality of cation exchange membranes (C membranes) 14 are alternately arranged in between to form a concentrating chamber 15 and a desalting chamber 16 alternately, and the desalting chamber 16 is ion-exchanged. An electric deionization device in which an anion exchanger and a cation exchanger composed of a resin, an ion exchange fiber, a graft exchange or the like are mixed or filled in a multi-layered form is often used (Japanese Patent Nos. 1782943, 2751090, and 2699256). issue). In FIG. 2, 17 is an anode chamber and 18 is a cathode chamber, and a spacer is generally provided.

The ions flowing into the desalting chamber 16 react with the ion exchanger based on their affinity, concentration and mobility, move in the direction of the potential gradient, and further move across the membrane. , Charge neutralization is maintained in all chambers. Then, due to the ion-selective permeation property of the membrane and the directionality of the potential gradient, the ions are reduced in the desalting chamber 16 and concentrated in the adjacent concentration chamber 15. That is, cations permeate the cation exchange membrane 14 and anions permeate the anion exchange membrane 13 to be concentrated in the concentration chamber 15. Therefore, deionized water (pure water) is collected from the desalination chamber 16 as production water.

Raw water is introduced into a desalting chamber 16 and a concentrating chamber 15, and deionized water (pure water) is taken out from the desalting chamber 16. On the other hand, the concentrated water in which the ions flowing out from the concentrating chamber 15 are concentrated is partly circulated to the inlet side of the concentrating chamber 15 by a pump (not shown) in order to improve the water recovery rate, and the rest is in the system. It is discharged out of the system as wastewater to prevent the concentration of ions.

Electrode water is also passed through the anode chamber 17 and the cathode chamber 18, and this electrode water has a conductivity of several tens of μS / cm or more in order to secure conductivity. Water is added or an electrolyte such as NaCl is added.

Japanese Unexamined Patent Publication (Kokai) No. 10-43554 proposes to fill the cathode chamber with electrically conductive particles, and USP 5,868,915 discloses to fill the electrode chamber with an ion conductive substance. It has been proposed, and when the electrode chamber is filled with an ion conductive substance in this way, the conductivity of the electrode chamber can be ensured by this ion conductive substance, and therefore, addition of an electrolyte to the electrode water or It is not necessary to replenish conductive water.

[0007]

The electric deionization apparatus in which the electrode chamber is filled with an ion conductive substance has the advantages that the electric resistance of the electrode chamber is small and the electric efficiency is high, but chlorine, etc., generated in the anode chamber. There is a problem that the ionic conductive material is deteriorated by the oxidizing agent, and there is a problem that the performance of the ion conductive material is deteriorated due to scale deposition in the cathode chamber, so that there is a problem that long-term operation cannot be continued.

An object of the present invention is to solve the above-mentioned conventional problems and to provide an electric deionization device capable of long-term operation by preventing deterioration of the performance of the ion conductive material filled in the electrode chamber.

[0009]

The electrodeionization device of the present invention comprises an anode chamber having an anode, a cathode chamber having a cathode, and
A concentration chamber and a desalination chamber alternately formed by alternately arranging a plurality of anion exchange membranes and cation exchange membranes are provided between the anode chamber and the cathode chamber, and the cation exchange membrane is provided in the anode chamber. In the electric deionization device, the concentrating chamber is adjacent to the cathode chamber via the anion exchange membrane, and the cathode chamber is adjacent to the concentrating chamber via the anion exchange membrane. Is characterized in that water or pure water from which anions have been removed is passed and water or pure water from which cations have been removed is passed into the cathode chamber.

In the electrodeionization apparatus of the present invention, since the electrode chamber is filled with the ion conductive substance, the electrode chamber has a small electric resistance and a high electric efficiency.

In the cathode chamber of the electric deionization apparatus, OH ⁻ is generated by the following reaction (1). When the electrode water containing cations is passed through the cathode chamber filled with the ion conductive material, calcium scale is produced in the cathode chamber by the following reaction (2), and the calcium scale production reaction is OH. ^- it is promoted by. 2H ₂ O + 2e ⁻ → 2OH ⁻ + H ₂ (1) Ca ²⁺ + CO ₃ ²⁻ → CaCO ₃ (2)

Therefore, when water containing Ca ²⁺ ions is passed through the cathode chamber filled with the ion conductive substance, the performance of the ion conductive substance deteriorates due to the scale generated in the cathode chamber.

In the present invention, since water or pure water from which cations such as Ca ²⁺ ions have been removed is passed through the cathode chamber, the formation of such scales is prevented, and the performance of the ion conductive material may deteriorate. Absent.

In the anode chamber, the following (3),
The reaction of (4) occurs, chlorine is generated, and the generated chlorine causes oxidative deterioration of the ion conductive material such as the ion exchange resin. 2H ₂ O → 4H ⁻ + 4e ⁻ + O ₂ (3) 2Cl ⁻ → 2e ⁻ + Cl ₂ (4)

In the present invention, since water or pure water from which anions such as Cl ⁻ ions have been removed is passed through the anode chamber, generation of chlorine is prevented and oxidative deterioration of the ion conductive material is prevented.

Ion exchange resin can be mentioned as the ion conductive material to be filled in the cathode chamber and the anode chamber. However, in the anode chamber, ozone (O ₃ ) having a strong oxidizing power is generated in addition to chlorine, so that the reducing action is performed. It is effective to use activated carbon having a certain amount, and the activated carbon may be used alone, or the activated carbon and the ion exchange resin may be mixed and used.

Further, it is preferable to use a substance carrying a heavy metal as the ion conductive substance, because the effect of increasing the conductivity of the heavy metal can obtain the effect of further reducing the electric resistance.

The water discharged from the cathode chamber contains hydrogen generated by the reaction (1). By making the cathode chamber outflow water containing this reducing hydrogen into the anode chamber inflow water, the oxidizing substances generated in the anode chamber can be reduced and removed, and the ionic conductive substance in the anode chamber is deteriorated by oxidation. Can be prevented more reliably. This cathode chamber outflow water has been removed from the cathode chamber through the anion exchange membrane to remove anion components such as Cl ^−, so that it can be effectively used as anion component-removed water that passes through to the anode chamber.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a schematic sectional view of an electric deionization apparatus showing an embodiment of the present invention.

This electrodeionization device is similar to the conventional electrodeionization device shown in FIG.
A plurality of anion exchange membranes (A membranes) 13 and cation exchange membranes (C membranes) 14 are alternately arranged between 2) to form concentration chambers 15 and desalting chambers 16 alternately. Chamber 16
Anion exchangers and cation exchangers composed of ion-exchange resins, ion-exchange fibers, graft exchangers, etc. are mixed or packed in multiple layers.

The anode chamber 17 and the cathode chamber 18 are provided with a cation exchange membrane 14 and an anion exchange membrane 13 respectively, and a concentration chamber 15 is provided between them.
And the anode chamber 17 and the cathode chamber 18 are filled with an ion conductive substance.

Raw water is introduced into the desalination chamber 16 and the concentration chamber 15, and the production water (pure water) is taken out from the desalination chamber 16.
A part of this produced water is used as the inflow water of the cathode chamber 18
It is delivered to the entrance side of 8. The outflow water from the cathode chamber 18 is fed to the inlet side of the anode chamber 17, and the outflow water from the anode chamber 17 is discharged as waste water to the outside of the system. A part of the concentrated water in which the ions flowing out from the concentrating chamber 15 are concentrated is circulated to the inlet side of the concentrating chamber 15, and the rest is discharged as waste water to the outside of the system.

In this electric deionization apparatus, since the anode chamber 17 and the cathode chamber 18 are filled with the ion conductive material, the electric resistance of the electrode chamber is small and the electric efficiency is high.

Examples of the ion conductive material include ion exchange resins, ion exchange fibers, and ion exchange materials such as graft exchange materials. The ion conductive material of the cathode chamber 18 includes anion exchange resin and cation exchange resin. It is preferable to use a mixed ion exchanger such as a mixed bed ion exchange resin with or a single anion exchanger such as an anion exchange resin.

On the other hand, as the ion conductive substance in the anode chamber 17, a mixed ion exchanger such as a mixed bed ion exchange resin of an anion exchange resin and a cation exchange resin, a cation exchanger such as a cation exchange resin alone, or activated carbon. Alternatively, a mixture of activated carbon and these ion exchangers can be used.

It is preferable to fill the anode chamber 17 with activated carbon, as described above, because it is possible to prevent oxidative deterioration in the anode chamber 17 due to the reducing action of the activated carbon.

Further, one or more heavy metals such as palladium, iron and manganese may be supported on a part or all of the ion exchanger such as ion exchange resin filled in the cathode chamber 18 and the anode chamber 17. By carrying such a heavy metal, the effect of further reducing the electric resistance is exhibited. In this case, the amount of the heavy metal supported is not particularly limited, but it is preferably about 0.5 to 10% by weight with respect to the ion exchanger.

When the activated carbon is used together with the ion exchanger or the heavy metal is supported on the ion exchanger, the activated carbon or the heavy metal-supported ion exchanger is filled along the electrode plate surface in the electrode chamber to preferentially react. That is also effective.

In the electric deionization apparatus of FIG. 1, since the production water (pure water) is passed through the cathode chamber 18 filled with the ion conductive material in this way, scale generation in the cathode chamber 18 is prevented and the scale caused by the scale is prevented. Performance deterioration of the ion conductive material is prevented.

Further, the cathode chamber 18 through which water is passed to the anode chamber 17
The effluent of is the pure water that has been passed through the anode chamber 17, does not contain anion components, and further contains hydrogen, which is a reducing substance generated by the electrode reaction in the cathode chamber 18, Oxidative deterioration of the ion conductive material in 17 is prevented.

The electrodeionization apparatus shown in FIG. 1 is an example of an embodiment of the electrodeionization apparatus of the present invention, and the present invention is not limited to the illustrated one unless it exceeds the gist thereof. is not.

For example, in the electric deionization apparatus of FIG. 1, the concentrating chamber 15 is not filled with an ion conductive substance, but this concentrating chamber is also filled with an ion conductive substance such as an ion exchanger, activated carbon or metal. May be. Further, in the electric deionization apparatus of FIG. 1, the product water is used as the inflow water of the cathode chamber 18, but as the inflow water of the cathode chamber 18, pure water or raw water of another system is treated by the cation exchange resin tower to remove the cation component. Water (soft water) may be used. As for the inflow water into the anode chamber 17, in addition to the outflow water from the cathode chamber 18, it is also possible to use production water, pure water of another system, or anion component-removed water obtained by treating raw water with an anion exchange resin tower. Further, it is not always necessary to circulate a part of the concentrated water, and if the quality of the produced water is more important than the water recovery rate, the raw water may be passed through in a transient manner. Etc. are also arbitrary.

[0034]

As described in detail above, according to the present invention, in an electrodeionization apparatus in which an electrode chamber is filled with an ion conductive substance to improve electric efficiency, the performance of the ion conductive substance filled in the electrode chamber is improved. It is possible to prevent the deterioration, and thereby to provide an electric deionization device capable of long-term continuous operation.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view of an electric deionization apparatus showing an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view showing a conventional electrodeionization device.

[Explanation of symbols]

11 Anode 12 cathode 13 Anion exchange membrane (A membrane) 14 Cation exchange membrane (C membrane) 15 Concentration room 16 Desalination chamber 17 Anode chamber 18 Cathode chamber

Continued front page    F-term (reference) 4D006 GA17 JA30C KA31 KD19                       MA13 MA14 PA01 PB02                 4D061 DA01 DB18 EA09 EB13 FA08                       FA17

Claims (4)

[Claims] 1. An anode chamber having an anode, a cathode chamber having a cathode, and a plurality of anion exchange membranes and cation exchange membranes alternately arranged between these anode chambers and cathode chambers are alternately formed. In the electric deionization device, the concentration chamber and the deionization chamber are provided, the concentration chamber is adjacent to the anode chamber via the cation exchange membrane, and the concentration chamber is adjacent to the cathode chamber via the anion exchange membrane, The anode chamber and the cathode chamber are filled with an ion conductive material, and water or pure water from which anions have been removed is passed through the anode chamber,
An electric deionization device characterized in that cation-removed water or pure water is passed through the cathode chamber. 2. The electric deionization device according to claim 1, wherein the ion conductive substance in the anode chamber is an ion exchange resin and / or activated carbon, and the ion conductive substance in the cathode chamber is an ion exchange resin. . 3. The electrodeionization device according to claim 2, wherein a heavy metal is carried on the ion conductive substance. 4. An electrodeionization device according to claim 1, wherein the cathode chamber outflow water is used as the anode chamber inflow water.