JPH10272474A - Electric deionization device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric deionization device with a deoxidizing function by mixing anion exchange resin and cation exchange resin to pack a desalting chamber with a mixture thereof, making a part of the anion exchange resin in the desalting chamber catalytic resin carrying metal, and feeding hydrogen to raw water to be introduced into the electric deionization device. SOLUTION: Plural anion exchange membranes A and cation exchange membrane C are alternately arranged in parallel to alternately form concentration chambers 1 and desalting chambers 2. The desalting chambers 2 each are packed with a mixture of ion exchange resin R, anion exchange resin and cation exchange resin, and catalytic resin in which metal is deposited on anion exchange resin. Ions in raw water are concentrated in the concentration chambers 1, and in the desalting chambers 2, water from which anion and cation components have been removed is produced. The raw water is contacted with the catalytic resin in the desalting chambers 2 in the presence of added gaseous H2 allowing dissolved oxygen(DO) to be decomposed and removed. In this way, water from which ions and DO have been removed is taken out as treated water through piping 12b and 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric deionization apparatus, and more particularly to an electric deionization apparatus having a deoxygenating function.

[0002]

2. Description of the Related Art Conventionally, in the production of demineralized water used for washing water for semiconductors, lenses, liquid crystals, etc., and medical water, a plurality of anion exchange membranes and cation exchange membranes are alternately arranged between electrodes and concentrated. An electric deionizer (“electrodeionizer” or “continuous deionizer”) in which a water chamber and a desalination chamber are alternately formed, and an anion exchange resin and a cation exchange resin are mixed and filled in the desalination chamber. ) Are frequently used. The electric deionizer is capable of effective desalination treatment, does not require regeneration like ion exchange resin, allows perfect continuous water sampling, and has the excellent effect of obtaining extremely high-purity water. To play.

In an electric deionization apparatus, ions in raw water flowing into a desalination chamber react with an ion exchange resin on the basis of affinity, concentration and mobility, and the direction of an electrode to which an electric potential is applied (the water to be treated). (Perpendicular to the flow) in the resin, and further across a cation exchange or anion exchange membrane separating the desalting and concentration chambers, maintaining charge neutralization in all chambers. Become like Then, due to the semi-osmotic characteristics and the potential of the ion exchange membrane, the ions in the raw water decrease in the desalting chamber and are concentrated in the adjacent concentrating chamber. Therefore, desalinated water is recovered from the desalination chamber.

A reverse osmosis (RO) membrane separation device is usually provided as a pretreatment means for such an electric deionization device. By disposing the RO membrane separation device, the electrolyte and TOC components in the raw water can be efficiently removed, the load on the electric deionization device can be reduced, and high-purity treated water can be obtained. become.

On the other hand, as a deoxidizing means for reducing dissolved oxygen (DO) in water, a deoxidizing catalyst supporting palladium (Pd) is used, and hydrogen (H ₂ ) or hydrazine (N ₂
A device that decomposes and removes DO in the presence of a reducing agent such as H ₄ ) has been used.

[0006]

A conventional electric deionization apparatus has only a deionization function and does not have a deoxygenation function. For this reason, when the electric deionizer is used for the production of pure water, an RO membrane separator, an electric deionizer and a deoxygenator are arranged, and the deionized water obtained from the electric deionizer is further separated. It is necessary to remove DO by treatment with a deoxidizer.

An object of the present invention is to solve the above-mentioned conventional problems and to provide an electric deionization apparatus having a deoxygenation function.

[0008]

The electric deionization apparatus of the present invention comprises a plurality of anion exchange membranes and cation exchange membranes arranged alternately to form a concentration chamber and a desalination chamber alternately.
In the electric deionizer in which the anion exchange resin and the cation exchange resin are mixed and filled in the desalination chamber, a part of the anion exchange resin in the desalination chamber is a catalyst resin supporting a metal, It is characterized by comprising means for supplying hydrogen to raw water introduced into the electrodeionization device.

In the electric deionization apparatus of the present invention, D in the raw water is contained in the deionization chamber in the presence of hydrogen as a reducing agent.
O is decomposed and removed by the action of the catalyst resin (2H ₂ + O ₂ → 2H ₂
O).

Since the catalyst resin itself has an anion exchange ability, there is almost no decrease in the desalination effect due to the use of a part of the anion exchange resin as the catalyst resin. Obtainable.

In the electric deionization apparatus, since a direct current flows between the anode and the cathode, cathode water containing hydrogen is discharged from the cathode chamber, and anode water containing oxygen is discharged from the anode chamber. . These cathode water and anode water need to be taken out of the system and subjected to gas-liquid separation treatment.
Cathode water treatment has been regarded as important, since there is a danger of explosion when the hydrogen concentration becomes high.

In the present invention, the cathode water containing hydrogen can be returned to the raw water side and used as a hydrogen source. In general, the cathode water of the electric deionization apparatus varies depending on the operating conditions, but contains about 0.5 to 5 ppm of dissolved hydrogen, so that the cathode water can be effectively used as a hydrogen source.

[0013]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of an electric deionization apparatus according to an embodiment of the present invention.

FIG. 1 is a system diagram showing an embodiment of an electric deionization apparatus according to the present invention.

In this electric deionization apparatus, a plurality of anion exchange membranes A and cation exchange membranes C are alternately arranged in parallel, and a concentration chamber 1 and a desalination chamber 2 are formed alternately. . The desalting chamber 2 is filled with the resin R. 3 is an anode, 4 is a cathode, 5 is an anode chamber, 6
Is a cathode chamber.

The desalting chamber 2 is filled with a mixture of an anion exchange resin and a cation exchange resin and a catalyst resin having a metal supported on the anion exchange resin. Further, an H ₂ gas injection pipe 10 is provided in the raw water introduction pipe 11.

In the present invention, the types and mixing ratios of the cation exchange resin and the anion exchange resin are not particularly limited.
In a normal case, the ratio of the cation exchange resin to the anion exchange resin containing the catalyst resin is preferably about 30 to 40%: about 60 to 70% (volume ratio).

The proportion of the catalyst resin is preferably about 10 to 40% (volume ratio) of the amount of the anion exchange resin containing the catalyst resin. If the ratio of the catalyst resin is lower than this, a sufficient deoxygenation function cannot be obtained, and if it is higher, the cost increases.

The catalyst resin may be any resin having a deoxygenating function, and there is no particular limitation on the metal to be supported. Examples thereof include noble metals such as Cu and Pd.
A noble metal such as d which has little elution to the treated water side is preferable. The amount of supported metal is generally 0.5 to 5 mg-metal / m
It is preferably about L-resin.

Specifically, as the catalyst resin, Pd is 1 to
"OC-1063", "OC-103" manufactured by Bayer Co., Ltd., a deoxygenation catalyst resin supported on a weakly basic anion exchange resin or a strongly basic anion exchange resin at a ratio of 3 mg-Pd / mL-resin.
1045 "can be used.

The amount of hydrogen added to raw water may be 1/4 to 1/8 of the DO concentration in water, generally about 1/8 of the theoretical amount. For example, if DO in raw water is 8 ppm, For example, it is added so that the hydrogen concentration becomes 1-2 ppm.

The method of adding hydrogen to raw water is not particularly limited as long as it can dissolve hydrogen in raw water, and there is no particular limitation on the location of addition. Is preferred.

In this electric deionization apparatus, raw water (usually, permeated water of an RO membrane separation apparatus (hereinafter referred to as “RO treated water”)
Called. ) Is a feed pipe 1 for the enrichment chamber 1
1a, a water supply pipe 11b to the desalting chamber 2, a water supply pipe 11c to the anode chamber 5, and a water supply pipe 11d to the cathode chamber 6, and after the H ₂ gas is injected from the pipe 10, It is supplied to the concentration room 1, the desalination room 2, the anode room 5 and the cathode room 4, respectively.

The ions in the raw water are concentrated in the concentration chamber 1,
In the deionization chamber 2, water from which anion and cation components are removed is produced. In this deionization treatment, the raw water comes into contact with the catalyst resin in the deionization chamber 2 in the presence of added H ₂ gas. DO is decomposed and removed. The water from which ions and DO have been removed in this manner is supplied from the desalination chamber 2 to the pipe 12.
It is taken out as treated water via b and 12.

On the other hand, the concentrated water discharged from the concentration chamber 1 through the pipes 13a, 13b and 13c is partially
Circulates to the raw water side, and the remainder is discharged out of the system from the pipe 14 as waste water. The concentrated water may be entirely returned to the raw water side.

The anode water discharged from the anode chamber 5 is O
_Since it contains oxidant components such as chlorine and ozone in addition to the above, if it is circulated to the raw water side, it will cause deterioration of the resin. .

On the other hand, the cathode water from the cathode chamber 6 is supplied to the pipe 16
Although discharged from a and 16b, since it contains hydrogen as described above, in the present invention, this cathode water may be used as a hydrogen source. In this case, the pipe 16 indicated by a broken line
By c, a part or all of the cathode is returned to the raw water side. By returning the cathode water in this way, the amount of H ₂ gas added separately can be reduced or made unnecessary.

[0028]

The present invention will be described more specifically below with reference to examples and comparative examples.

First, a comparative example will be described for convenience of explanation.

Comparative Example 1 RO membrane of Atsugi City water (“SU-720” 1 manufactured by Toray Industries, Inc.)
Main) Treated water is electrically deionized continuously (Kurita Kogyo Co., Ltd.)
(“Pure Conte”) (800 L / h)
r), the quality of the obtained treated water (desalted water) was examined, and the results are shown in Table 1.

The electric continuous deionizer used was an anion exchange resin (“PA31” manufactured by Mitsubishi Chemical Corporation) in a desalting chamber.
6 ”) and a cation exchange resin (“ PK2 ”manufactured by Mitsubishi Chemical Corporation).
28 ") and 35:65 (volume ratio).

Example 1 In Comparative Example 1, 20% of the anion exchange resin was deoxygenated by Bayer "OC-1045" (Pd was carried on a strongly basic anion exchange resin at a ratio of 2 mg-Pd / mL-resin). (Catalyst resin) and in the RO treated water supplied to the electric continuous deionization apparatus, the H ₂ gas is dissolved so that the dissolved H ₂ concentration becomes 1 to 1.2 ppm (１ ／ to 1/7 of DO). The same treatment was carried out except for the supply, and the quality of the obtained treated water was examined. The results are shown in Table 1.

Example 2 In Example 1, in order to reduce the supply of H ₂ gas, the cathode water (dissolved hydrogen concentration: 2 to 3 ppm) discharged at a rate of 40 L / hr was returned to the RO treated water side. The treatment was carried out in the same manner except that the dissolved hydrogen concentration was adjusted to 1 to 1.2 ppm, and the quality of the treated water obtained is shown in Table 1.

In this embodiment, the amount of H ₂ gas used is reduced to 12% in the first embodiment by returning the cathode water.
To 13%.

[0035]

[Table 1]

As shown in Table 1, according to the present invention, a part of the anion exchange resin in the demineralized water production chamber is replaced with a catalyst resin, and deoxygenation can be performed by an electric deionization apparatus only by providing a hydrogen supply means. In addition, even if the anion exchange resin is replaced with a catalyst resin, the desalting ability is not impaired,
It is understood that high-purity treated water can be obtained with O.

[0037]

As described above in detail, the electric deionization apparatus of the present invention has a deoxygenation function, so that the deoxygenation means required in the conventional processing equipment can be omitted or reduced in size. It is extremely advantageous industrially and economically.

[Brief description of the drawings]

FIG. 1 is a system diagram showing an embodiment of an electric deionization apparatus of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Concentration room 2 Demineralization room 3 Anode 4 Cathode 5 Anode room 6 Cathode room A Anion exchange membrane C Cation exchange membrane R Ion exchange resin

Claims (2)

[Claims] 1. An enrichment chamber and a desalination chamber are formed alternately by alternately arranging a plurality of anion exchange membranes and cation exchange membranes, and an anion exchange resin and a cation exchange resin are provided in the desalination chamber. In the electric deionization apparatus mixed and filled, a part of the anion exchange resin in the deionization chamber is a catalyst resin supporting a metal, and hydrogen is supplied to raw water introduced into the electric deionization apparatus. An electric deionization apparatus characterized by comprising means for performing: 2. The apparatus according to claim 1, wherein the means for supplying hydrogen includes means for returning cathode water containing hydrogen discharged from the electric deionization apparatus to an inlet side of raw water. Electric deionizer.