JP2002001345A - Electrically regenerative method for manufacturing deionized water, its manufacturing apparatus and ion exchange layer used therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel electrically regenerative apparatus for manufacturing deionized water by which the lowering of performance due to impurities such as a hardness component in water to be treated is prevented and eliminated. SOLUTION: The ion exchanger to be set in a concentrating chamber consists at least two layers different in water permeability, the layer lower in water permeability is arranged on the ion-exchange membrane side, and an anion- exchange group is provided at least on the surface. Consequently, the hardness component is never deposited or accumulated on the surface of the anion- exchange membrane on the anode side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for producing deionized water by an electric regeneration type deionization (hereinafter referred to as EDI) technique. In detail, highly deionized deionized water called pure water or ultrapure water used in various manufacturing industries such as pharmaceutical manufacturing industry, semiconductor manufacturing industry, foodstuff industry, or boiler water and research facilities is efficiently used. The present invention relates to a method and an apparatus for producing regenerated deionized water, and an ion exchanger layer used in the method.

[0002]

2. Description of the Related Art Conventionally, as a method for producing deionized water, generally, a method of obtaining deionized water by flowing treated water through a packed bed of ion exchange resin and adsorbing and removing impurity ions on the ion exchange resin is generally used. It is a target. In this method, it is necessary to regenerate the ion-exchange resin having reduced exchange / adsorption ability, and the regeneration is usually performed using an acid or an alkali. As a result, in this method, there is a problem that a waste liquid caused by the acid or alkali is discharged together with a troublesome regeneration operation.

[0003] Therefore, a method of producing deionized water that does not require regeneration is desired. In recent years, an EDI method that does not require a regeneration operation using a chemical solution has been developed and put into practical use. In this method, a mixture of an anion exchange resin and a cation exchange resin is placed in a desalting chamber of an electrodialysis tank in which an anion exchange membrane and a cation exchange membrane are alternately arranged, and the water to be treated is placed in the desalting chamber. This is to perform electrodialysis by applying a voltage while flowing concentrated water into the concentrated room, which is formed and arranged alternately with the demineralization room while flowing, thereby producing deionized water and regenerating the ion exchange resin. This is a method which does not need to separately regenerate the ion exchange resin.

That is, in the conventional EDI method, a cation exchange membrane and an anion exchange membrane are alternately arranged between an anode chamber provided with an anode and a cathode chamber provided with a cathode, and the anode side is partitioned by an anion exchange membrane and the cathode is separated. An anion exchange resin and a positive electrode are placed in a desalination chamber of an electrodialysis tank in which a desalination chamber defined by a cation exchange membrane on the side and a concentration chamber defined on the anode side by a cation exchange membrane and the cathode side defined by an anion exchange membrane. Using a deionized water production apparatus containing an ion exchange resin, the treated water flows into the desalination chamber while applying a voltage, and the treated water or a part of the treated water is used as concentrated water in the concentration chamber. By flowing the impurities, impurity ions in the water to be treated are removed.

According to this method, as described above, since the ion exchanger is continuously regenerated at the same time as the production of deionized water, a regeneration step using a chemical such as an acid or an alkali and a waste liquid treatment used for the regeneration are unnecessary. However, at this time, the EDI device gradually increases the electric resistance due to hardness components such as calcium ions and magnesium ions in the water to be treated, causing an increase in applied voltage or a decrease in current. There is a problem in that the specific resistance of the treated water produced decreases due to a decrease in desalination performance.

[0006] Therefore, many methods for overcoming such a problem have been proposed. For example, water to be supplied to an EDI device is subjected to a reverse osmosis membrane treatment in two stages in advance to remove a hardness component as much as possible. After that, the water is supplied as the water to be treated by the EDI method (Japanese Patent Laid-Open No. 40220/1990), or the acid water generated in the anode chamber by electrolyzing water in a separately prepared acidic water generating electrolytic tank is supplied to the concentration chamber of the EDI method. There is a method of passing water (JP-A-10-128338). By adopting such a method, the long-term performance of the EDI method can be stabilized, but the investment cost is increased, and as a result, there is another problem that the advantage of the EDI system is reduced as compared with other deionization methods. Will be.

A method for intermittently weakening the water to be treated supplied to the desalting chamber to intermittently elute the ionic components strongly adsorbed on the ion exchange resin in the desalting chamber (Japanese Patent Laid-Open No. 3-26)
390) has been proposed, but there is a problem in that the resistivity of the treated water decreases during the intermittent treatment. Further, an aqueous solution of an alkali metal hydrochloride or sulfate is added to adjust the conductivity to 100 to 80.
A method has been proposed in which a solution having a concentration of 0 μS / cm is supplied to a concentration chamber of the EDI method to stabilize the current flowing in the EDI method and obtain high-purity treated water (Japanese Patent Application Laid-Open No. 9-24374). No long-term stability has been disclosed.

Further, besides the above, an ion exchanger is made of E
Proposal of a method (WO 98/20972) of not only filling the desalting chamber of the DI device but also filling the concentrating chamber, thereby lowering the electric resistance and stabilizing the current to obtain high-purity treated water. A method of loading an anion exchangeable spacer net into a concentration chamber (Clean Technology 1998.10 No.6)
(P. 4), it is reported that the electrical resistance can be reduced, and as a result, the precipitation of the hardness component is also reduced, but they are not always sufficient.

[0009]

SUMMARY OF THE INVENTION The present invention relates to a conventional ED.
The present invention relates to a method for solving the above-mentioned problems of a deionized water production system and a method for producing an improved deionized water having a long-term stability, which has been proposed thereafter, and more particularly to a hardness component of the water to be treated supplied in the EDI method. SUMMARY OF THE INVENTION It is an object of the invention to provide a novel EDI desalination system that prevents and eliminates performance degradation caused by impurities of the invention.

[0010] To describe the problem in more detail, in the conventional deionized water production apparatus by the EDI method,
Since the concentrated water is circulated and used, the hardness components are concentrated in the concentration chamber as the operation proceeds, and the hardness component (calcium and magnesium) ions are transferred from the desalting chamber through the anion exchange membrane to OH ions and carbonates. By binding to ions to form hydroxides or carbonates, which precipitate and accumulate, the electrical resistance is increased and a favorable ion exchange state may be impaired.

According to the study of the present inventors, Na in the concentration chamber
Cations such as ions, Ca ions, and Mg ions are distributed most in the vicinity of the anion exchange membrane due to the potential gradient. On the other hand, it was found that OH ions generated by the water dissociation reaction in the desalting chamber permeate and move through the anion exchange membrane and reach the concentration chamber, so that high concentrations of OH ions exist near the anion exchange membrane. As a result, it was found that on the surface of the anion exchange membrane on the side of the enrichment chamber and in the vicinity thereof, hardness components such as Ca ions and Mg ions, and OH ions and carbonate ions are bonded to cause a phenomenon called scale precipitation.

The present invention has been made on the basis of the results of the above-mentioned research and the facts that have been found. The present invention prevents the precipitation and accumulation of hardness components on the surface of the anion exchange membrane on the side of the concentration chamber, and provides an ED.
Provided is a method and apparatus for producing deionized water by EDI technology, which suppresses an increase in the electrical resistance of the apparatus I and has a long-term stability without reducing the purity of the produced deionized water, and an ion exchanger layer used therefor. The purpose is to do.

[0013]

SUMMARY OF THE INVENTION The present invention provides a method and an apparatus for producing deionized water of the electric regeneration type for solving the above-mentioned problems, an ion exchanger layer having a small water permeability and a large ion contained in a concentration chamber. It provides an exchanger layer, of which the electric regeneration type deionized water production apparatus alternates a cation exchange membrane and an anion exchange membrane between an anode chamber having an anode and a cathode chamber having a cathode. It is arranged and forms a desalination chamber where the anode side is partitioned by an anion exchange membrane and the cathode side is partitioned by a cation exchange membrane, and a concentration chamber where the anode side is partitioned by a cation exchange membrane and the cathode side is partitioned by an anion exchange membrane. The ion exchanger is accommodated in the desalting chamber and the concentrating chamber of the electrodialysis tank, and the water is supplied to the desalting chamber while applying a voltage between the two electrodes to remove impurities in the water. Type deionized water production equipment In this regard, the ion exchanger accommodated in the concentration chamber is composed of at least two layers having different water permeability, and the layer having a small water permeability is disposed on the anion exchange membrane side, and has an anion exchange group on at least the surface. It is characterized by being.

In the method for producing deionized water with electric regeneration, deionized water is produced by using the above-mentioned apparatus for producing deionized water with electric regeneration. A porous anion exchanger layer having an average particle diameter of 10 to 600 µm and comprising an anion exchange resin having a thickness of 100 to 8000 µm; and an anion exchange fiber having an average fiber diameter of 10 to 600 µm and having a thickness of 50 to 8000 µm. Body layer, porous ion-exchange layer coated with a compound having an anion-exchange property on a cation-exchange resin having an average particle diameter of 10 to 600 μm, or an average fiber diameter of 10 to 600
It comprises a porous ion exchanger layer in which a cation exchange fiber is coated with a compound having an anion exchange property.

Further, the ion-exchanger layer having high water permeability accommodated in the concentration chamber has an average particle diameter of 300 to 10000 μm.
A porous ion exchanger layer having a thickness of 1000 to 10000 μm, comprising an anion exchange resin or a cation exchange resin alone or a mixture of an anion exchange resin and a cation exchange resin, an anion exchange fiber having an average fiber diameter of 20 to 2000 μm or Thickness 1000 composed of cation exchange fiber alone or a mixture of anion exchange fiber and cation exchange fiber
Porous ion-exchanger layer having a mean particle size of 3 to 10,000 μm
A thickness of 1000 to 1000 μm, in which a cation exchange resin is coated with a compound having an anion exchange property.
A thickness of 1000-1 μm in which a porous ion-exchange layer of 10,000 μm or a cation-exchange fiber having an average fiber diameter of 20-2000 μm is coated with a compound having an anion-exchange property.
Any of a 0000 μm porous ion exchanger layer.

In the present invention, by employing the above-mentioned means, the ion exchanger is accommodated in the concentrating chamber in addition to the desalting chamber, and the ion exchanger comprises at least two layers having different water permeability. In addition, since a layer having low water permeability is disposed on the side of the anion exchange membrane and has at least an anion exchange group on the surface, the precipitation of the hardness component on the surface of the anion exchange membrane and in the vicinity thereof on the concentration chamber side. In addition, the accumulation can be prevented, and even if the apparatus for producing the electric regeneration type deionized water is operated for a long time, the voltage rise can be suppressed and the specific resistance of the produced deionized water does not decrease.

In the present invention, the ion exchanger is accommodated in the concentrating chamber in addition to the desalting chamber, and the ion exchanger is composed of at least two layers having different water permeability, and a layer having a small water permeability is used as a shade. By being disposed on the ion exchange membrane side and having at least an anion exchange group on the surface, precipitation and accumulation of the hardness component can be prevented, and an increase in electrical resistance due to the hardness component can be suppressed, and the produced deionized water can be suppressed. Although the reason why the specific resistance does not decrease and the decrease in the deionization performance can be suppressed, the mechanism and the like have not been sufficiently elucidated, the present inventors presume as follows.

As described above, in the conventional EDI apparatus, the surface of the anion exchange membrane on the side of the enrichment chamber has a high OH ion concentration, and the concentration of calcium ions and magnesium ions also increases due to a potential gradient. At this time, if the concentration chamber is simply filled with an ion exchanger, the concentrated liquid containing hardness components such as calcium ions and magnesium ions that have passed through the cation exchange membrane from the desalting chamber is promptly placed on the anion exchange membrane side. Move to the surface, exposed to high concentrations of OH ions,
The hardness component compound will precipitate.

However, according to the present invention, the ion exchanger is also accommodated in the concentration chamber, and the ion exchanger is composed of at least two layers having different water permeability, and a layer having a small water permeability is provided on the anion exchange membrane side. It is arranged and has at least an anion exchange group on the surface, and as a result, after the concentrated liquid containing a large amount of the hardness component that has moved through the layer with high water permeability reaches the layer with low water permeability, It can be explained that the moving force is reduced and it is prevented from flowing into the surface of the anion exchange membrane on the concentration chamber side.

In addition, the hardness component ions that have reached the layer having a low water permeability from the layer having a high water permeability are combined with the anion exchange functional groups formed on the surface of the layer having a low water permeability. Due to the electrical repulsion of the same kind of ions, it is difficult to penetrate into the surface of the layer having low water permeability. As a result, the reaction between the OH ion and the hardness component ion is reduced, and the hardness component on the surface of the anion exchange membrane on the concentration chamber side is reduced. It can be explained that the precipitation and accumulation of the compound are suppressed, and the electric resistance and the deionization performance are stabilized.

The above description is provided to facilitate understanding of the present invention, and the present invention is not limited to the description, but is defined by the appended claims. Needless to say, there is. Hereinafter, embodiments of the invention that can be employed in the present invention will be described. However, the present invention is not limited to the description, and may be specified by the description of the claims. Needless to say, the same as above.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, an ion exchanger packed in a concentration chamber is composed of at least two layers having different water permeability, of which an ion exchanger layer having a small water permeability has at least a surface. It has an anion exchange group and is disposed on the anion exchange membrane side of the concentration chamber. The ion-exchange layer having high water permeability is disposed on the cation exchange membrane side of the ion-exchange layer having low water permeability.

In the ion exchanger layer having low water permeability, the water permeability at a pressure of 35 kPa is 1 kg · cm ⁻¹ ·
h ^-1 or more is preferable, and in particular, 10 to 50 kg · cm ⁻¹ · h ⁻¹
Is more preferable. In the ion exchanger layer having high water permeability, the water permeability at a pressure of 35 kPa is preferably 10 kg · cm ⁻¹ · h ⁻¹ or more, and particularly preferably 30 to 3
More preferably, the pressure is 00 kg · cm ⁻¹ · h ⁻¹ .

The difference in water permeability between the ion-exchange layer having a low water permeability and the ion-exchange layer having a high water permeability is 5 kg · cm ⁻¹ ··· in the water permeability at a pressure of 35 kPa.
h ⁻¹ or more is preferable, and particularly preferably 10 kg · cm ⁻¹ · h ⁻¹ .

In the present invention, the layer having low water permeability accommodated in the concentrating chamber is formed of an ion exchanger having an anion exchange group on the surface. There is a so-called anion exchange resin or anion exchange fiber having a property, and other examples thereof include a cation exchange resin and an ion exchanger in which an anion exchange functional group is provided on the surface of the cation exchange fiber.

As a method for providing an anion exchange group on the surface of the cation exchanger as described above, an anion exchange group or a monomer, oligomer solution or polymer solution which can be converted into an anion exchange group is prepared by using a raw material cation exchange group. A method of fixing an anion exchange group to the surface of the cation exchanger by means such as adhesion, polymerization or drying on the body surface is preferably used. Such anion exchange groups or monomers that can be converted to anion exchange groups include ethyleneimine,
Examples thereof include vinylamine, vinylpyridine, allylamine, chloromethylstyrene, and the like. Methods for immobilizing them on the surface of the raw material cation exchanger include radical polymerization and radiation polymerization.

Also, polyethyleneimine, polyallylamine, polyamidine, hexamethylenediamine-epichlorohydrin polycondensate, dicyandiamide-formalin polycondensate, guanidine-formalin polycondensate, polyvinylbenzyltrimethylammonium chloride, poly (4-
Vinylpyridine), poly (2-vinylpyridine), poly (dimethylaminoethyl acrylate), poly (dimethylaminoethyl methacrylate), poly (1-vinylimidazole), poly (2-vinylpyrazine), poly (4
-Butenylpyridine), poly (N, N-dimethylacrylamide), poly (N, N-dimethylaminopropylacrylamide) or a water-soluble polymer containing a salt thereof.

The method of immobilizing them on the surface of the raw material cation exchanger includes a method of heating after attaching to the raw material cation exchanger, a method of using formalin, a reactive site in the polymer, for example, using active hydrogen bonded to a nitrogen atom. A method of insolubilizing by reacting with epichlorohydrin or an alkylene dihalide, or a method of preparing an organic solvent solution of a water-insoluble copolymer containing the above water-soluble cationic polymer unit or an organic solvent solution of an aminated polysulfone-based polymer on the surface of a cation exchanger. And then fixation by heat treatment. Such a coating treatment on the cation exchanger for forming an anion-exchange functional group, even before being stored in the concentration chamber,
It can be carried out even after storing in the concentration room.

The water-permeable layer having an anion-exchange group on the surface provided on the anion-exchange membrane side of the above-mentioned concentrating chamber has the same or smaller porosity than the layer having a large water-permeable property. The maximum pore size of the pores is preferably not more than 2/3 of the maximum pore size of the pores of the layer having a large water permeability, whereby the precipitation and accumulation of the hardness component can be prevented. A predetermined performance can be achieved.

At this time, when the porosity is large, the concentrated solution containing the hardness component flows through the layer having low water permeability, and as a result, the concentration of the hardness component on the surface of the anion exchange membrane increases, and the hardness component is easily precipitated. Unfavorably, the ion exchanger is therefore preferably filled in the enrichment chamber with a porosity of 10 to 50% by volume. The reason is that, when the porosity of the ion exchanger through which water permeates is 50% by volume or more, the capacity ratio of the ion exchanger having high electric conductivity is reduced, so that the electric resistance of the concentrating chamber increases,
Further, since the ability to prevent precipitation of the hardness component is reduced, the porosity is 1
The filling is performed so as to be 0 to 50% by volume, preferably 15 to 40% by volume.

The maximum pore size of the pores of the layer having a low water permeability is not less than 2/3 that of the layer having a high water permeability, since the concentrated liquid containing the hardness component easily flows through the layer, The electric repulsion effect on the polyvalent cation due to the anion exchange group is small and the polyvalent cation is easily permeated, which is not preferable. Therefore, the maximum pore size of the water-permeable layer is preferably 2/3 or less. Is preferably 以下 or less.

As for the specific pore size of the void, the maximum pore size is preferably 200 μm or less. When the maximum pore diameter of the gap of the ion exchanger of the layer having a small water permeability is 200 μm or more,
The polyvalent cations in the concentrated solution are more easily supplied to the anion exchange membrane surface, and the ability to prevent the precipitation of the hardness component is reduced.
It is good to be 00 μm or less, preferably 100 μm or less. The maximum pore diameter of the ion exchanger in the present invention is determined by the bubble point method described in ASTM F-316.

The layer having a small water permeability having an anion exchange group on the surface accommodated in such a concentrating chamber may have an average particle diameter of not more than 2/3 of the maximum pore size of the layer having a large water permeability.
Thickness of 100 to 600 μm made of anion exchange resin
8000 μm porous anion exchanger layer, average fiber diameter 1
A thickness of 50 to 600 μm comprising anion exchange fibers of 0 to 600 μm
8000 μm porous anion exchanger layer, average particle size 10
A porous ion-exchanger layer in which a compound having an anion exchange property is coated on a cation exchange resin having a thickness of ~ 600 μm or a compound having an anion exchange property is coated on a cation exchange fiber having an average fiber diameter of 10 to 600 μm. A porous ion exchanger layer is exemplified.

In the present invention, an ion exchanger placed on the cation exchange membrane side of a highly water-permeable ion exchanger layer accommodated in a concentration chamber, ie, a low-permeable ion exchanger layer having an anion exchange group on its surface. The layer can be used without any limitation as long as the water permeability at a pressure of 35 kPa is 10 kg · cm ⁻¹ · h ⁻¹ or more so that a required amount of liquid can be supplied to the concentration chamber. , Anion exchange resin, cation exchange fiber, anion exchange fiber, net (net) -like body into which ion exchange group is introduced, or resin, fiber, net with anion exchange property on the surface of cation exchanger Is exemplified.

The pressure accommodated in the above-mentioned concentration chamber is 35 kPa
Water permeability in the 10 kg · cm ^- at ¹ · h ^-1 or more, the ion exchanger layer is disposed on the cation exchange membrane side of the water permeable small layer, More specifically, the average particle size Anion-exchange resin or cation-exchange resin having a thickness of 300 to 10,000 μm alone or a mixture of anion-exchange resin and cation-exchange resin in a thickness of 1,000 to 10,000
There is a μm porous ion exchanger layer.

In another form, the average fiber diameter is 20
There is a porous ion exchanger layer having a thickness of 1000 to 10000 [mu] m consisting of an anion exchange fiber or a cation exchange fiber alone or a mixture of anion exchange fiber and a cation exchange fiber. As a specific example of such a porous ion exchanger layer, an ion exchange group is introduced into an olefin-based net having a fiber diameter of 200 to 2000 μm and a thickness of 400 to 4000 μm, and a 400 to 10,000 μm net obtained by installing them in one layer or multiple layers. There is a state ion exchanger layer.

When the ion exchanger layer is a cation exchanger, an ion exchanger layer whose surface is coated with a compound having an anion exchange property can be preferably used. In this case, a cation exchange resin having an average particle diameter of 300 to 1000 μm or a cation exchange fiber having an average fiber diameter of 20 to 2000 μm is coated with a compound having an anion exchange property. It is good to make a layer.

[0038] Regarding the filling of the two layers, a layer having a low water permeability and a layer having a high water permeability, into the concentration chamber, the wet granules are evenly packed in the concentration chamber, or the volume when wet is concentrated. The semi-dried or dried granules are stored in a concentration chamber on the assumption that the volume is 1.0 to 1.5 times the chamber volume, and water is supplied to swell to fill the entire concentration chamber. Can be achieved. In addition, an ion exchanger molded body having a water-permeable gap, which is previously formed into a shape that can be easily stored in a concentration chamber with an ion exchanger and a binder, is also preferably used.

The water-permeable small layer filled in the concentration chamber is
In the case of a cation exchange resin or a cation exchange fiber, if the surface is not previously coated with a thin anion exchangeable layer, at least a desalination treatment of the feed water having a hardness component is carried out. By supplying a liquid containing an anion-exchange compound to the layer and treating it in an EDI apparatus, an anion-exchange group can be formed on the surface of the layer having low water permeability.

The general configuration of the electro-regeneration type deionized water producing apparatus of the present invention in which both the low water permeable layer and the high water permeable layer are filled in a concentration chamber is as follows. . That is, a plurality of cation exchange membranes and anion exchange membranes are alternately arranged between an anode chamber provided with an anode and a cathode chamber provided with a cathode, and the anode side is partitioned by the anion exchange membrane, and the cathode side is provided. A desalting chamber filled with a cation exchanger and an anion exchanger partitioned by a cation exchange membrane, an anode side partitioned by a cation exchange membrane, and a cathode side partitioned by an anion exchange membrane; 1 to 300 sets alternately include an ion exchanger layer having an anion exchange group on the surface with a small water permeability on the side and a concentration chamber filled with a water permeable ion exchanger layer on the cation exchange membrane side. Arrange them in series. It is possible to carry out desalination by flowing an electric current while flowing the water to be treated into the desalting chamber and flowing the water for discharging the concentrated salts into the concentrating chamber of the EDI water producing apparatus thus configured. it can. A voltage of about 2 to 10 V at which water dissociation occurs in the desalting chamber can be applied to each unit cell.

Members other than the ion exchanger packed in the concentration chamber used in the EDI water producing apparatus of the present invention, that is, anion exchange membrane, cation exchange membrane, anion exchanger packed in the desalination chamber and cation exchange The body can be used without any particular restrictions. For example, as the ion exchanger filled in the desalting chamber, a mixture of an anion and a cation exchange resin, a layer in which an anion exchange resin layer and a cation exchange resin layer are alternately stacked in a multi-stage in the flow direction of the water to be treated. The structure, an anion exchange resin phase and a cation exchange resin phase are in a mosaic pattern, a lattice pattern, or a sea phase in which one of the ion exchange resin layers is continuous and an island phase in which various ion exchange resin phases are scattered in the sea phase. A packing body is illustrated. Examples of forms other than the granular form include a mixture of an ion exchange fiber and an ion exchange resin, a mixture of anion and cation exchange fibers, and a composite of an ion exchanger and a conductor.

[0042]

Next, the present invention will be described in more detail with reference to examples and examples of the production of ion exchangers to be filled in the concentration chamber. However, the present invention is not limited to these examples and production examples. Rather, it is, of course, specified based on the claims.

[Production Example 1] Two ion-exchange monolayers having different water permeability to be filled in a concentration chamber were prepared as follows. Strongly basic (Cl type) anion exchange resin having an average particle size of 550 μm (manufactured by Mitsubishi Chemical Corporation, trade name: Diaion SA-10)
A) is passed through a 365 μm sieve with a particle size of
The mixture was divided into particles having a particle size of 5 μm or more for 2 minutes. Then, 97% by mass of each sieved resin and 3% by mass of linear low density polyethylene (manufactured by Dow Chemical Company, Affinity SM-1300) were kneaded at 120 to 130 ° C.

The obtained kneaded material is thermoformed at 130 ° C. in a flat plate press, and is made of a resin having an average particle diameter of 600 μm and a thickness of 4 m.
An anion exchange molded article (2) having a thickness of 2 mm and comprising an anion exchange molded article (1) having an average particle size of 300 m and a resin having an average particle diameter of 300 μm was prepared. The anion exchange molded article (1) has a water permeability of 3
At 5 kPa, the pressure was 130 kg · cm ⁻¹ · h ⁻¹ and the maximum pore diameter of the gap was 220 μm. On the other hand, the water permeability of the anion exchange molded article (2) was 20 kg · cm ⁻¹ · h ⁻¹ , and the maximum pore diameter of the gap was 50 μm.

[Production Example 2] Two ion exchange monolayers having different water permeability filled in a concentration chamber had an average particle size of 550 μm.
m strong basic (Cl type) anion exchange resin (trade name: Diaion SA-10A, manufactured by Mitsubishi Chemical Corporation) instead of a strongly acidic (Na type) cation exchange resin having an average particle size of 600 μm
(Manufactured by Mitsubishi Chemical Corporation, trade name: DIAION SK-1B), except that the average particle diameter was 650 μm.
4 mm thick cation exchanger compact (1) made of resin and 2 mm thick made of resin having an average particle size of 300 μm
(2) was prepared. The cation exchange molded body (1) has a water permeability of 150 kg · cm ⁻¹ · h ^{−1 at} a pressure of 35 kPa and an average pore diameter of the gap of 250 μm.
Met. On the other hand, the water permeability of the cation exchange molded product (2) was 25 kg · cm ⁻¹ · h ⁻¹ , and the average pore diameter of the gap was 60 μm.

Next, the above-mentioned cation-exchange molded product was added to a dimethylformamide solution containing 100 ppm of a polysulfone block copolymer having an anion exchange capacity of 2.0 meq / g and prepared according to JP-A-2-21257. 2) was immersed and then dried at 80 ° C. to prepare an ion exchange molded product (3) having an anion exchanger layer on the surface. Water permeability is 23 kg · c at a pressure of 35 kPa.
m ⁻¹ · h ⁻¹ , and the average pore diameter of the gap was 55 μm.

[Production Example 3] Each member to be mounted on the EDI water production apparatus was produced as follows. A binder polymer consisting of a mixture obtained by mixing and kneading 70% by weight of low-density polyethylene and 30% by weight of ethylene-propylene-diene rubber with a Labo Plastomill at 150 ° C. for 30 minutes, and a strongly basic anion exchange resin (manufactured by Mitsubishi Chemical Corporation) Diaion SA-10
A) The dry pulverized product (A) (average particle size: 50 μm) was mixed at a mixing ratio of 4
0/60 (mass ratio).
Kneading was performed at 0 ° C. and 50 rpm for 20 minutes.

The obtained kneaded material was 160
The resulting mixture was heated and melt-pressed at 0 ° C. to prepare an anion exchange membrane 1 having a thickness of 500 μm. Further, the cation exchange membrane paired with the anion exchange membrane was manufactured in Production Example 3 except that a strongly acidic cation exchange resin (Diaion SK-1B manufactured by Mitsubishi Chemical Corporation) was used.
A cation exchange membrane 1 having a thickness of 500 μm was prepared in the same manner as in the case of the anion exchange membrane 1.

As for the ion exchanger to be charged into the desalting chamber, a cation exchange resin, an anion exchange resin and a binder were mixed and molded into a plate to prepare an ion exchange molded article (4) having a thickness of 6 mm. For both ion exchange resins,
A sulfonic acid type (H type) cation exchange resin having an average particle size of 600 μm and an ion exchange capacity of 4.5 meq / g dry resin (manufactured by Mitsubishi Chemical Corporation, trade name: Diaion SK-1)
B) and an average particle size of 550 μm and an ion exchange capacity of 3.
5 meq / g dry resin quaternary ammonium salt type (OH
Type) Anion exchange resin (manufactured by Mitsubishi Chemical Corporation, trade name: DIAION SA-10A) having an ion exchange capacity ratio of 50
/ 50.

[Example 1] An anion exchange membrane 1 and a cation exchange membrane 1 prepared as described above were alternately arranged, and were produced in a desalination chamber containing an ion exchange molded body (4) and in Production Example 1. The anion exchange molded article (1) having a thickness of 4 mm and a maximum pore diameter of 220 μm was accommodated in the cation exchange membrane side, and the anion exchange molded article (2) having a thickness of 2 mm and a maximum pore diameter of 50 μm was accommodated in contact with the anion exchange membrane. An effective area of 507 cm ² consisting of a filter press type dialysis tank in which the concentrating chamber is fastened via a chamber frame (made of polypropylene) [width (= chamber frame width)
13 cm, vertical (= desalting length) 39 cm] × 3 pairs of electrodialysis tanks.

Using an EDI water producing apparatus equipped with this electrodialysis tank, industrial water was subjected to sand filtration, and then the treated water shown in Table 1 treated in one stage of the reverse osmosis membrane apparatus was supplied to the desalination chamber while supplying current to the desalting chamber. , And operated continuously for 1000 hours under the conditions shown in Table 2 to examine the voltage change and the stability of the deionized water specific resistance. The results are shown in Table 3 with the applied voltage and the specific resistance of deionized water at the initial stage and after 1000 hours of operation.

[0052]

[Table 1]

[0053]

[Table 2]

[0054]

[Table 3]

Example 2 Instead of the anion exchange molded article (1) housed in the concentration chamber in Example 1, the cation exchange molded article (1) of Production Example 2 and the anion exchange molded article (2) ) Was replaced with an ion-exchange molded article (3) having an anion-exchange group on the surface, and a deionization test was performed in the same manner as in Example 1. The results are shown in Table 3.

Example 3 Instead of the ion-exchange molded product (3) having an anion-exchange group on the surface in Example 2, a fibrous anion-exchange filter paper (IONEX TIN- manufactured by Toray Industries, Inc.) was used.
A deionization test was performed in the same manner as in Example 2 except that 100H10P, a maximum pore diameter of 40 μm, and a thickness of 2 mm) were used, and the results are shown in Table 3.

Comparative Example 1 The cation exchange molded article (1) in Example 2 was placed on the anion exchange membrane side, and the ion exchange molded article (3) having an anion exchange group on the surface was placed on the cation exchange membrane side. And a deionization test was conducted in the same manner as in Example 2 except that the arrangement of the ion exchanger in the concentration chamber was reversed from that in Example 2. The results are shown in Table 3.

[Comparative Example 2] Instead of the ion-exchange molded article (3) having an anion-exchange group on its surface in Example 2, a cation-exchange molded article (2) before an anion-exchange group was provided.
A deionization test was carried out in the same manner as in Example 2 except that was used, and the results are shown in Table 3.

Table 3 showing the results of the above Examples and Comparative Examples
As is clear from, by installing a water-permeable small layer having an anion exchange group on the surface on the anion exchange membrane side of the concentration chamber and a water-permeable large layer on the cation exchange membrane side, It can be seen that the voltage is low and stable, and the specific resistance of deionized water is high and stable.

[0060]

According to the present invention, the ion exchanger accommodated in the concentration chamber comprises at least two layers having different water permeability,
By installing a water-permeable layer having at least anion-exchange groups on the surface on the side of the anion-exchange membrane, it is possible to prevent the precipitation and accumulation of hardness components on the side of the anion-exchange membrane in the concentration chamber, and to produce EDI water. Even if the apparatus is operated for a long time, there is no increase in voltage and there is no decrease in the specific resistance of deionized water.

Continued on the front page (72) Inventor Takeshi Ken Komatsu 1150 Hazawa-machi, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture Inside the Asahi Glass Co., Ltd. (72) Inventor Yukio Matsumura 10 Goi Kaigan, Ichihara-shi, Chiba Prefecture Asahi Glass Co., Ltd. F-term (reference) 4D006 GA17 KB01 KB11 MA03 MA13 MA14 MC09X MC22X MC68X NA50 NA62 NA65 PB06 PC02 4D025 AA04 AB19 BA08 BA13 BA25 BA28 DA05 DA06 4D061 DA03 DB13 EA09 EB01 EB04 EB13 EB17 EB19 EB22 FA09

Claims (9)

[Claims] A cation exchange membrane and an anion exchange membrane are alternately arranged between an anode chamber having an anode and a cathode chamber having a cathode, and the anode side is partitioned by an anion exchange membrane and the cathode side is cation exchange membrane. An ion exchanger is provided in a desalination chamber and a concentration chamber of an electrodialysis tank which has a desalination chamber partitioned by a membrane and a concentration chamber partitioned by a cation exchange membrane on the anode side and a cathode side partitioned by an anion exchange membrane. In the electric regeneration type deionized water producing apparatus that accommodates and supplies the water to be treated to the desalination chamber while applying a voltage between the two poles to remove impurity ions in the water to be treated, the ion exchanger accommodated in the enrichment chamber is The layer comprising at least two layers having different water permeability and having a low water permeability is disposed on the anion exchange membrane side and has an anion exchange group on at least the surface thereof. Ion water production equipment. 2. An ion exchanger layer having high water permeability accommodated in a concentration chamber has a water permeability of 10 at a pressure of 35 kPa.
2. The electric regeneration type deionized water production apparatus according to claim 1, wherein the pressure is not less than kg · cm ⁻¹ · h ⁻¹ . 3. The method according to claim 1, wherein the maximum pore size of the pores of the layer having low water permeability accommodated in the concentration chamber is not more than 2/3 of the maximum pore size of the pores of the ion exchanger layer having high water permeability. The electric regeneration type deionized water producing apparatus according to the above. 4. A layer having a small water permeability accommodated in a concentration chamber is a porous anion exchanger layer having a thickness of 100 to 8000 μm and comprising an anion exchange resin having an average particle diameter of 10 to 600 μm, and an average fiber diameter of 10 to 600 μm. A porous anion exchanger layer having a thickness of 50 to 8000 μm comprising an anion exchange fiber, a cation exchange resin having an average particle diameter of 10 to 600 μm, and a porous ion exchanger layer coated with a compound having an anion exchange property, 4. An electro-regeneration type deionized water producing apparatus according to claim 1, wherein the porous ion exchanger layer is a cation exchange fiber having an average fiber diameter of 10 to 600 [mu] m coated with a compound having an anion exchange property. . 5. The ion-exchanger layer having a high water permeability accommodated in the concentration chamber may be made of an anion-exchange resin or a cation-exchange resin having an average particle diameter of 300 to 10,000 μm alone or an anion-exchange resin and a cation-exchange resin. A porous ion exchanger layer having a thickness of 1000 to 10000 μm comprising a mixture,
Anion-exchange fiber or cation-exchange fiber having an average fiber diameter of 20 to 2000 μm, or a thickness of 1000 to 10 consisting of a mixture of anion-exchange fiber and cation-exchange fiber alone
000 μm porous ion exchanger layer, average particle size 300 to
A thickness of 1000 to 100 in which a cation exchange resin having a thickness of 1000 μm is coated with a compound having an anion exchange property.
00 μm porous ion exchanger layer or average fiber diameter 20
Thickness of 1000 to 1000 in which a compound having an anion exchange property is coated on a cation exchange fiber of ２０００2000 μm
The electric regeneration type deionized water producing apparatus according to claim 1, 2 or 3, which is a porous ion exchanger layer having a thickness of 0 µm. 6. The water to be supplied to the desalting chamber has an electric conductivity of 1 to 5.
At 200 μS / cm, the hardness component is 1 in terms of calcium carbonate.
The electric regeneration type deionized water producing apparatus according to any one of claims 1 to 5, wherein the apparatus has a pressure of 0 to 2000 ppb. 7. A porous anion exchanger layer having a thickness of 100 to 8000 μm and comprising an anion exchange resin having an average particle diameter of 10 to 600 μm, and a porous layer having a thickness of 50 to 8000 μm and comprising anion exchange fibers having an average fiber diameter of 10 to 600 μm. Porous anion exchanger layer, a porous ion exchanger layer in which a cation exchange resin having an average particle diameter of 10 to 600 μm is coated with a compound having an anion exchange property, or an average fiber diameter of 10 to 600 μm
A cation exchange fiber comprising a porous ion exchanger layer coated with a compound having an anion exchange property, at least a surface disposed on the anion exchange membrane side in a concentration chamber of an electro-regeneration type deionized water production apparatus. An ion exchanger layer having a small water permeability and having an anion exchange group. 8. A porous ion-exchanger layer having a thickness of 1,000 to 10,000 μm comprising an anion exchange resin or a cation exchange resin having an average particle diameter of 300 to 10,000 μm alone or a mixture of an anion exchange resin and a cation exchange resin.
Anion-exchange fiber or cation-exchange fiber having an average fiber diameter of 20 to 2000 μm, or a thickness of 1000 to 10 consisting of a mixture of anion-exchange fiber and cation-exchange fiber alone
000 μm porous ion exchanger layer, average particle size 300 to
Thickness 1000 to 100 in which a compound having an anion exchange property is coated on a 1000 μm cation exchange resin
00 μm porous ion exchanger layer or average fiber diameter 20
Thickness of 1000 to 1000 in which a compound having an anion exchange property is coated on a cation exchange fiber of ２０００2000 μm
Ions having high water permeability, which are disposed on the cation exchange membrane side of the ion exchanger layer having low water permeability in the concentration chamber of the electro-regeneration type deionized water production apparatus which is one of the porous ion exchanger layers of 0 μm. Exchanger layer. 9. A cation exchange membrane and an anion exchange membrane are alternately arranged between an anode chamber having an anode and a cathode chamber having a cathode, and the anode side is partitioned by an anion exchange membrane and the cathode side is cation exchange membrane. An ion exchanger is provided in a desalination chamber and a concentration chamber of an electrodialysis tank which has a desalination chamber partitioned by a membrane and a concentration chamber partitioned by a cation exchange membrane on the anode side and a cathode side partitioned by an anion exchange membrane. In the electric regeneration type deionized water production method of supplying the water to be treated to the desalination chamber while removing the impurity ions in the water to be treated while applying a voltage between the two poles, the ion exchanger accommodated in the enrichment chamber, Electroregenerating deionized water production, characterized in that at least two layers having different water permeability and at least a layer having a small water permeability having an anion exchange group on the surface are arranged on the anion exchange membrane side. Method.