JPH11165175A - Manufacturing apparatus for deionized water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent creases of an ion-exchange membrane from being generated by a method wherein a specific % or higher of an ion-exchange group of a cation exchange membrane or an anion exchange membrane is made to be a regenerative type, which is built in an electrodialysis tank under a wetting state to be applied to passing water. SOLUTION: 70% or higher, preferably about 90% or higher of an ion exchange group of a cation exchange membrane K or an anion exchange membrane A is made to be a regenerative type. The cation exchange membrane K and the anion exchange membrane A are arranged by about 5 pairs between an anodic chamber 2 and a cathodic chamber 3 in an order of a spacer not/the anion exchange membrane A/a platy porous ion exchanger/the cation exchange membrane K, and built in an electrodialysis tank 1 under a wetting state. Demineralization chambers R1 to Rn and enriching chambers S1 to Sn are made to be between both ion exchange membranes K, A. By executing dialysis treatment by passing water through an electrodialysis tank 1, creases of the ion-exchange membranes K, A can be prevented from being generated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a cation exchange membrane and an anion exchange membrane which are alternately arranged, and an ion exchanger is accommodated in a desalination chamber of an electrodialysis tank having a desalination chamber and a concentration chamber. The present invention relates to an apparatus for producing deionized water in which a voltage is applied while flowing water to be treated through a desalination chamber.

[0002]

2. Description of the Related Art As an apparatus for producing deionized water, water to be treated is caused to flow through a packed bed of a cation exchange resin and an anion exchange resin, and impurity ions are adsorbed and removed by the ion exchange resin. It is common to get. At that time, a method of regenerating a cation exchange resin and an anion exchange resin having reduced adsorption capacity by using an acid and an alkali, respectively, is adopted. As a result, in this apparatus, there is a problem that the waste liquid of the acid and alkali used for the regeneration is discharged. Therefore, there is a demand for an apparatus for producing deionized water which does not require the regeneration.

[0003] From such a viewpoint, an apparatus for producing deionized water by self-regenerating electrodialysis using an ion exchange resin and an ion exchange membrane in recent years has attracted attention. In this apparatus, an anion exchange membrane and a cation exchange membrane are alternately arranged, and an ion exchanger is accommodated in a desalination chamber of an electrodialysis tank having a desalination chamber and a concentration chamber. It produces deionized water by applying voltage while flowing treated water and performing electrodialysis, and self-regenerates ion-exchange resin and ion-exchange membrane using acid and alkali by water dissociation in a desalination chamber. I have.

[0004] In this conventional apparatus, various ideas and developments have already been carried out, including, for example, an apparatus in which the width and thickness of a desalting chamber are limited (Japanese Patent Application Laid-Open No. 61-107906).
And Japanese Patent Application Laid-Open No. 1-307410 discloses an apparatus in which water to be treated is passed through a desalination chamber of a deionizer at least two times.
Japanese Patent Application Laid-open No. Hei 4 (1994), discloses an apparatus for converting an ion exchange resin filled in a portion through which water to be treated first passes into an anion exchange resin.
-71624).

[0005]

An ion exchange membrane used in a deionized water producing apparatus is usually set (incorporated) in an electrodialysis tank in a wet state, and after the setting, water flow is started and continued. As the process proceeds, generation of “wrinkles” is observed in the ion-exchange membrane, and in extreme cases, occurrence of breakage of the membrane and generation of pinholes are observed. Conventionally, there is no appropriate technique for solving such a problem, and the above three conventional ideas are not proposals for solving this problem. The present inventor has conducted research and development to solve this problem, and as a result, the present invention has been completed.

[0006] As the present inventors proceed with research and development,
Of particular note was the fact that "wrinkles" were generated in the ion exchange membrane as water flowed, and the present invention was developed by focusing on this point. In other words, looking at the manufacturing technology of ion-exchange membranes based on this focus, ion-exchange membranes are usually loaded under ion-exchange groups after they are manufactured due to the manufacturing constraints of manufacturing without deteriorating or deteriorating their ion-exchange properties. It is a type. As a result, the ion-exchange membrane before setting is in a load type and has a low swelling degree, whereas the ion-exchange groups are regenerated as water is supplied and electricity is applied after setting, so that the swelling degree increases and wrinkles occur. The present inventor thought that this would be the case.

[0007]

In order to solve the above problems, the present invention employs a deionized water producing apparatus in which a cation exchange membrane and an anion exchange membrane are alternately arranged, and In a deionized water producing apparatus in which an ion exchanger is accommodated in a desalting chamber of an electrodialysis tank having a chamber and a concentrating chamber, and electricity is supplied while flowing water to be treated through the desalting chamber, a cation exchange membrane is used. Alternatively, 70% or more of the ion exchange groups of the anion exchange membrane are incorporated into the electrodialysis tank in a regenerated wet state, and water is passed through the electrodialysis tank.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION As the ion exchange membrane used in the present invention, not only a homogeneous ion exchange membrane but also a heterogeneous ion exchange membrane composed of a powdery ion exchange resin and a binder polymer has strength and flexibility. It is preferable from the viewpoint of. As a method for producing a heterogeneous ion exchange membrane, a method in which a powdery ion exchange resin and a binder polymer are mixed and kneaded under heating and then extruded under heating to form a sheet is preferably used. The method of forming into a sheet is not limited to the above-mentioned heat extrusion molding, and known means such as a heat press can be adopted.

Regarding the functional groups of the ion exchange resin used for producing the heterogeneous ion exchange membrane, a sulfonic acid type strongly acidic group in the case of a cation exchange resin, and a quaternary ammonium base in the case of an anion exchange resin. And strongly basic groups such as pyridinium bases, but not limited thereto, and weakly acidic groups such as carboxylic acid groups and phosphoric acid groups, and weakly basic groups such as secondary amino groups and tertiary amino groups, respectively. It may be.

The particle size of the ion exchange resin is preferably such that the maximum particle size is not more than 150 μm and
It is preferable that the particles having a particle diameter of 150 μm account for 5% by weight or less of the entire raw material of the ion exchange resin particles, and the particles having a particle diameter of 20 μm or less account for 20% by weight or less. Maximum particle size is 15
If the particle size is 0 μm or more or 100 to 150 μm and the content is 5% by weight or more, pinholes are likely to be generated during molding, and the mechanical strength of the film is undesirably reduced.

When the particle size of the ion-exchange resin is 20 μm or less and 20% by weight or more, the surface area of the ion-exchange resin particles is significantly increased, the kneading with the binder polymer is insufficient, and defect points are easily generated. Is not preferred. Further, if the heating and kneading are sufficiently performed to eliminate the defect points, it takes a long time or the kneading temperature rises, so that the ion exchange group is decomposed and the electric resistance of the membrane is remarkably increased.

Examples of the binder polymer for the heterogeneous ion exchange membrane include low-density polyethylene, linear low-density polyethylene, ultra-high-molecular-weight high-density polyethylene, high-density polyethylene, polypropylene, and a mixture thereof with a flexible rubber material. can give. Among them, low-density polyethylene and a mixture of ethylene-propylene rubber, ethylene-propylene-diene rubber or a rubber material containing these two rubbers are particularly preferred in terms of strength, elongation and flexibility of the obtained ion exchange membrane. Preferred polymers.

When the binder polymer is a mixture of low-density polyethylene and a rubber material, the content of the rubber material with respect to the whole binder polymer is preferably from 10 to 50% by weight. If the rubber content is less than 10% by weight, the obtained film becomes brittle, and if it is more than 50% by weight, the film becomes soft and weak to pressure deformation, which is not preferable. A rubber material having a content of 25 to 35% by weight is particularly preferable because excellent properties can be obtained in the above-mentioned physical properties and molding is easy.

When a low-density polyethylene and a mixture of ethylene-propylene rubber or ethylene-propylene-diene rubber are further mixed with another polymer as a binder polymer, the polymer may be high-density polyethylene, ultra-high molecular weight high-density Polyolefins such as polyethylene, polypropylene and polyisobutylene are preferred.

The mixing ratio of the crushed ion exchange resin particles and the binder polymer is preferably such that the weight ratio of ion exchange resin / binder polymer is 40/60 to 70/30. If the amount of the ion exchange resin is less than 40% by weight, the resulting heterogeneous ion exchange membrane has an undesirably high electric resistance. If the amount of the ion exchange resin exceeds 70% by weight, it is not preferable because the mechanical strength decreases and molding becomes impossible.

The method for preparing the regenerative heterogeneous ion exchange membrane used in the present invention includes a method for producing a heterogeneous ion exchange membrane using a regenerative ion exchange resin as a raw material, and a method for preparing a heterogeneous ion exchange resin using a load type ion exchange resin as a raw material. There is a method in which a homogeneous ion exchange membrane is produced and then converted into a regenerative heterogeneous ion exchange membrane by an acid or alkali treatment. Although there are the two methods described above, the former is not preferable because the regenerative ion exchange resin has low heat resistance and the ion exchange group is decomposed during the heat forming of the heterogeneous ion exchange membrane to reduce the ion exchange capacity.

When converting an anion exchange membrane or a cation exchange membrane to a regenerative type, it is necessary that at least 70% of the ion exchange groups present in the ion exchange membrane be of a regenerative type, preferably at least 90%. It is better to make it a type. The regeneration treatment for conversion is preferably an acid treatment for a cation exchange membrane, and an alkali treatment for an anion exchange membrane. Here, the regenerative type refers to a state in which OH ⁻ is bonded to an anion exchange group in the case of an anion exchange membrane, and H ⁺ is bonded to a cation exchange group in the case of a cation exchange membrane. Refers to the state of having done.

The types of acids used include hydrochloric acid, sulfuric acid,
Nitric acid or the like is preferable, and the processing conditions include a concentration of 0.1 to
3M, a temperature of 25 to 70 ° C, and a time of 0.5 to 48 hours are preferably used. Further, as the kind of alkali, sodium hydroxide, potassium hydroxide and the like are preferable, and as the processing conditions, a concentration of 0.1 to 3 M, a temperature of 25 to 70 ° C., and a time of 0.5 to 72 hours are preferably used. If the concentration of the acid and the alkali is less than 0.1M, the treatment takes a long time. If the concentration is more than 3M, the film is deteriorated and the cleaning takes a long time, which is not preferable.

When the temperature of the regeneration treatment is lower than 25 ° C., the conversion of the ion-exchange groups to the regeneration type is not sufficient,
When the temperature is higher than ° C, the membrane is deformed or the ion exchange group is decomposed, which is not preferable. If the time is shorter than 0.5 hour, the conversion of the ion-exchange group to the regenerative type is not sufficient, and if the time is longer than 72 hours, the membrane is deteriorated and cleaning takes a long time, which is not preferable. Regarding the temperature and the time, 7
It is necessary to select so that 0% or more is converted to a regenerative type, and it is preferable to select so that 90% or more becomes a regenerative type.

The ion exchanger accommodated in the desalting chamber of the electrodialysis tank may be a granular ion exchange resin,
A porous ion exchanger may be formed by molding an ion exchange resin into a plate shape using a binder polymer. Examples of the method of forming into a plate shape include a method of heating and mixing a dry ion-exchange resin and a binder polymer, and a method of removing the solvent after dissolving the binder polymer in a solvent, mixing with the ion-exchange resin, and forming. .

The ion exchanger formed into a plate shape is a suitable ion exchanger for use in the present invention because of its low electric resistance because it is easy to handle and easy to fill and has good adhesion between ion exchange resins. As for the porosity of the porous ion exchanger, a continuous porosity involved in the passage of the liquid is preferably 5% by volume or more. If it is less than 5% by volume, the flow rate of the liquid decreases and the pressure loss increases, which is not preferable. When the porosity is 10 to 40% by volume, water permeability is also good,
It is particularly preferable because of excellent desalination performance and high-purity treated water. The porosity is a value when the porous ion exchanger is accommodated in a desalting chamber and used.

The porous ion exchanger may be one containing cation exchange resin particles or anion exchange resin particles alone, or one containing a mixture thereof. In the case of a mixture containing a mixture, the portion containing the cation exchange resin particles and the portion containing the anion exchange resin particles preferably have a phase-separated structure combined like a sea-island structure or a layered structure. Particularly preferred. However, in any case, the ratio of the total amount of the cation exchange resin particles to the total amount of the anion exchange resin particles accommodated in one desalting chamber is defined as the total ion exchange capacity ratio of cation exchange resin / anion exchange resin = 3
It is preferably 0/70 to 80/20. If the total ion exchange capacity ratio is out of this range, the purity of the treated water may be undesirably reduced.

The weight fraction of the binder polymer used in the porous ion exchanger is preferably 20% or less based on the entire porous ion exchanger. If the weight fraction is more than 20%, the surface of the ion-exchange resin particles is coated with the binder polymer to lower the adsorption performance, and the porosity decreases, so that the flow rate of the liquid to be treated decreases and the pressure loss increases. Not preferred. Especially, the weight fraction of the binder polymer is preferably 1 to 5%.

The binder polymer used for the porous ion exchanger is preferably a thermoplastic polymer or a solvent-soluble polymer from the viewpoint of the production method of the porous ion exchanger. As such a binder polymer,
The following can be preferably used. First, as the thermoplastic polymer, low-density polyethylene, linear low-density polyethylene, ultra-high-molecular-weight high-density polyethylene, polypropylene, polyisobutylene, polyvinyl acetate and ethylene-vinyl acetate copolymer, and the like.Examples of the solvent-soluble polymer include Natural rubber, butyl rubber, polyisoprene, polychloroprene, styrene-butadiene rubber, nitrile rubber, vinyl chloride-fatty acid vinyl ester copolymer and the like.

The thickness of the plate-like porous ion exchanger to which the ion exchange resin is bound by using the binder polymer is 1 to 3
00 mm is preferred. If the thickness is less than 1 mm, the thickness of the desalting chamber accommodating the thinner is extremely thin, and as a result, it is difficult to flow water, the amount of treated water is reduced, and the pressure loss may be increased. If the thickness is larger than 300 mm, the electric resistance may be increased, which is not preferable.
More preferably, the thickness of the ion-exchange resin molded body is 3 to 50 mm. This thickness is a value when the porous sheet is accommodated in a desalting chamber and used.

The type of the apparatus for producing deionized water in the present invention is described in, for example, Japanese Patent Application Laid-Open No. Hei 3-18640.
0, JP-A-2-277526 and JP-A-5-275.
It is preferable to use an electrodialysis tank described in US Pat. No. 64726, US Pat. No. 4,632,745 and US Pat. No. 5,425,866. That is, the electrodialysis tank has a structure in which a plurality of cation exchange membranes and anion exchange membranes are preferably alternately arranged via a chamber frame between an anode chamber having an anode and a cathode chamber having a cathode. ing. In such a case, in the present invention, in the cation exchange membrane and the anion exchange membrane, 70% or more of the ion exchange groups are regenerated and arranged in a wet state. In this case, when the ion exchanger accommodated in the desalting chamber has a plate shape, such a plate ion exchanger is inserted and arranged between the ion exchange membranes.

Thus, in the electrodialysis tank, a desalting chamber in which the anode side is partitioned by the anion exchange membrane and the cathode side is partitioned by the cation exchange membrane, and the anode side is partitioned by the cation exchange membrane,
Preferably about 2 to 50 sets of concentrating chambers whose cathode side is partitioned by an anion exchange membrane are alternately formed. The thickness of the frame-shaped chamber frame having an opening at the center interposed between the cation exchange membrane and the anion exchange membrane defines the thickness of the desalination chamber and the concentration chamber. The thicknesses of the chamber frames of the desalting chamber and the concentrating chamber need not always be the same. Preferably, a net-shaped spacer (separator) is inserted and arranged in the concentration chamber to maintain the thickness at a predetermined thickness. At this time, if the ion exchanger is not stored in the desalting chamber of the assembled electrodialysis tank, the granular ion exchanger is stored at this stage.

Thereafter, the water to be treated is flowed into the desalting chamber of the electrodialysis tank, and while the water for discharging the concentrated salts is flown into the concentrating chamber, the ion exchange membrane of the electrodialysis tank is shrunk by the water. By shifting to a steady state while preventing wrinkles from occurring, and by passing an electric current therewith, desalination of the water to be treated can be performed. During normal operation of the electrodialysis tank, a voltage of preferably about 4 to 20 V is applied to each unit cell, and a current density of preferably 0.00001 to
Electricity is supplied at 0.05 A / cm ² .

FIG. 1 is a diagram schematically showing one embodiment of the apparatus for producing deionized water of the present invention. In this figure, A
Is an anion exchange membrane and K is a cation exchange membrane. These anion exchange membrane A and cation exchange membrane K are
.. Dn and the enrichment chamber frames C1, C2, C3... Cn are arranged at predetermined intervals, thereby forming the anode chamber 2, the enrichment chambers S1, S2.・ ・
.. Sn, the desalting chambers R1, R2,... The demineralization chambers R1, R2,..., Rn are filled with an anion-exchange ion exchanger, and spacers N1, N2, N3,.

In FIG. 1, reference numeral 4 denotes an anode,
Reference numeral 5 denotes a cathode, and a predetermined voltage is applied between both electrodes during operation. This allows the desalination chambers R1, R2,.
The anion component in the liquid to be treated, which is introduced into the solution, permeates and transfers to the concentration chamber on the anode side through the anion exchange membrane A, while the cation component in the liquid to be treated passes through the cation exchange membrane K to the concentration chamber on the cathode side. Then, the liquid to be treated is deionized and discharged through the conduit 7. Also, the concentrated solution was
Through each of the concentration chambers S1, S2,..., Sn, where the anions and cations permeated and transferred as described above are collected and discharged from the conduit 9 as a concentrate.

The cations in the water to be treated captured by the cation exchanger in the desalting chamber are given a driving force by an electric field and sequentially pass through the cation exchanger in contact with the captured cation exchanger. To reach the cation exchange membrane and then pass through the membrane to the concentration chamber. Similarly, anions in the water to be treated captured by the anion exchanger move to the concentration chamber via the anion exchanger and the anion exchange membrane. From this fact, if the cation exchanger and anion exchanger are aggregated in a certain area to form an aggregation area, the number of contact points between the same type of ion particles is significantly increased, so that the movement of ions becomes easier, and It is more preferable because ionic performance is improved.

[0032]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples, but it is a matter of course that the present invention is not limited to these Examples. In addition, Examples and Comparative Examples will be compared, and the excellent effects of the present invention will be specifically described based on the comparison.

(Example 1) As a binder polymer,
70% by weight of low density polyethylene and 30% by weight of ethylene-propylene-diene rubber
The mixture was mixed and kneaded at 30 ° C. for 30 minutes to obtain a mixture. On the other hand, as the ion exchange resin, Mitsubishi Chemical Diaion SK-1B (styrene-divinylbenzene copolymer resin, ion exchange group-SO ₃ Na type, apparent density 0.825 g / ml, moisture Using a content of 43 to 50% by weight and an ion exchange capacity of 2.0 meq / ml),
After drying with hot air at 24 ° C. for 24 hours, pulverization was performed with a jet mill. The pulverized particles were removed with a stainless mesh sieve to remove particles having a particle size of 150 μm or more. Obtained particle size 150μ
When the particle size distribution of the ion-exchange resin powder particles having a particle size of 100 μm or less was measured at 1.2% by weight, and the particles having a particle size of 20 μm or less were 12% by weight.
Met.

The ion-exchange resin particles and the low-density polyethylene / ethylene-propylene-diene rubber mixture were mixed at a mixing ratio of 60/40 (weight ratio) and kneaded with a Labo Plastomill at 130 ° C., 50 rpm for 20 minutes. The obtained kneaded material was heated and melt-pressed at 160 ° C. by a flat plate press to obtain a cation exchange membrane having a thickness of 500 μm. After immersing the obtained membrane in ion-exchanged water at 50 ° C. for 24 hours,
The substrate was immersed in 1M hydrochloric acid at 16 ° C. for 16 hours to convert the ion-exchange group into a regenerated type, and washed with ion-exchanged water. When Na ⁺ in the obtained cation exchange membrane was chemically quantified, 99% or more of the ion exchange groups were converted to the regenerated form. The dimensional change of the membrane after the hydrochloric acid treatment was determined by setting the membrane dimension after the ion-exchanged water treatment to 100%.
%, 101.5% in the plane direction and 1 in the thickness direction
44.7%.

Similarly, Diaion SA-1 manufactured by Mitsubishi Chemical is a strong basic anion exchange resin as the ion exchange resin.
0A (styrene-divinylbenzene copolymer resin, ion exchange group-N (CH ₃ ) ₃ Cl type, apparent density 0.685 g)
/ Ml, a water content of 43 to 47% by weight, and an ion exchange capacity of 1.3 meq / ml) to obtain an anion exchange membrane having a thickness of 500 µm. The particle size distribution of the used ion exchange resin powder particles having a particle size of 150 μm or less is as follows.
The particles having a particle diameter of 20 μm or less were 8% by weight.

The obtained membrane was immersed in ion-exchanged water at 50 ° C. for 24 hours, and then immersed in 1 M sodium hydroxide at 40 ° C.
It was immersed for a period of time to convert the ion-exchange group into a regeneration type, and washed with ion-exchanged water. The resulting Cl anion-exchange membrane ^- chemically more than 99% of the ion exchange group was quantified had been converted into regenerative a. The dimensional change of the membrane after the sodium hydroxide treatment was 102.0% in the plane direction and 103.10 in the thickness direction when the membrane size after the ion-exchanged water treatment was 100%.
6%.

Next, a sodium sulfonate type cation exchange resin (Diaion SK-1B, manufactured by Mitsubishi Chemical Corporation) having a particle size of 400 to 600 μm and an ion exchange capacity of 4.5 meq / g and a particle size. Quaternary ammonium salt type anion exchange resin (Diaion SA-10A manufactured by Mitsubishi Chemical Co., Ltd., trade name: 400-600 μm, ion exchange capacity: 3.5 meq / g dry resin) is dried with hot air at 80 ° C. Was adjusted to 3% by weight, and then mixed at a cation exchange resin / anion exchange resin = 44/56 (weight ratio in a dry state) to obtain a mixture having an ion exchange capacity ratio of 50/50.

A linear low-density polyethylene (Affinity SM-1300, manufactured by Dow Chemical Company) is added to the mixture.
And 3% by weight, and kneaded at 120 to 130 ° C. The obtained kneaded material was thermoformed at 130 ° C. by a flat plate press to obtain a porous ion exchanger sheet having a thickness of 0.6 cm. The porosity of the continuous voids of this porous sheet was 23% by volume, and the water content was 2.0% by weight.

The above-mentioned dried plate-like porous ion exchanger, regenerative cation exchange membrane and regenerative anion exchange membrane are placed between an anode and a cathode by a spacer net / anion exchange membrane / plate-like porous ion. 5 in the order of exchanger / cation exchange membrane
Paired and assembled into the electrodialyzer shown in FIG. The thickness of the desalting chamber of the electrodialysis tank was 8 mm. The spacer net (opening diamond) arranged in the concentration chamber is made of polypropylene, and has a yarn diameter of 0.5 mm, a pitch distance (distance between the centers of the diagonal yarns) of 3 mm, and a yarn intersection thickness of 1.2 m.
m, the thickness of the concentration chamber frame was 1.2 mm. The volume filling ratio of the plate-like porous ion exchanger in the desalting chamber was 52% in a dry state.

As shown in FIG. 1, a desalting chamber frame (made of polypropylene having a thickness of 8 mm) and a concentrating chamber frame (made of polypropylene having a thickness of 1.2 mm) are interposed between the cation exchange membrane and the anion exchange membrane. The filter press type dialysis tank had an effective area of 520 cm ² × 5 pairs. After supplying water having a conductivity of 5 μS / cm for 10 minutes to the desalting chamber, the concentrating chamber, and the bipolar chamber of the electrodialysis tank, and then pre-energizing for 15 hours to sufficiently wet the porous ion exchanger, Production of deionized water was performed. Desalination was performed by using a water having an electric conductivity of 5 μS / cm as raw water and applying a voltage of 4 V per unit cell to obtain 0.5 m of pure water having an electric conductivity of 0.06 μS / cm.
^A stable production rate of ³ / h was obtained. After the measurement, the ion-exchange membrane was taken out and the state was observed. As a result, it was in a state where tension was sufficiently applied due to shrinkage, and no wrinkles were generated.

(Example 2) As an ion exchanger packed in a desalination chamber, a sodium sulfonate type cation exchange resin having a particle size of 400 to 600 µm and an ion exchange capacity of 4.5 meq / g (Mitsubishi) Quaternary ammonium salt type anion exchange resin (trade name: Diaion SK-1B manufactured by Chemical Co., Ltd.) and particle size of 400 to 600 μm, ion exchange capacity: 3.5 meq / g (Diamond, manufactured by Mitsubishi Chemical Corporation) A test was conducted in the same manner as in Example 1 except that a mixed and dried product of the ions SA-10A) was used and the structure of the desalting chamber was a structure capable of preventing the outflow of the granular ion exchange resin. The moisture content of the mixed dried product was 8% by weight, the cation exchange resin / anion exchange resin mixture ratio was 44/56 (weight ratio in a dry state), the ion exchange capacity ratio was 50/50, and the dry ion exchange resin mixture was used. Was charged into the desalting chamber at a volume filling rate of 50%.

In the same manner as in Example 1, the ion exchange resin was sufficiently wetted by passing water through each chamber of the electrodialysis tank for 10 minutes and pre-energizing for 15 hours, and then subjected to a production test of deionized water. Was. The electrodialysis tank used had an effective area of 520 cm ² × 5 pairs. Desalination was performed by using a water having a conductivity of 5 μS / cm as a raw water and applying a voltage of 4 V per unit cell to obtain a treated water having a conductivity of 0.08 μS / cm.
It was obtained stably at a production rate of 42 m ³ / h. After the measurement, the ion-exchange membrane was taken out and the state was observed. As a result, it was in a state where tension was sufficiently applied due to shrinkage, and no wrinkles were generated.

(Comparative Example 1) A test was performed in the same manner as in Example 1 except that the cation exchange membrane was not treated with hydrochloric acid and the anion exchange membrane was not treated with sodium hydroxide. . In each of these membranes, the regenerated type accounted for 1% or less of the ion exchange groups. Desalination was performed by applying a voltage of 4 V per unit cell using water having an electric conductivity of 5 μS / cm as raw water.
/ Cm low purity treated water was obtained at a production rate of 0.35 m ³ / h. After the measurement, the ion-exchange membrane was taken out and the state of observation was observed. As a result, a large number of folds and wrinkles were generated, and there was a portion where pinholes were generated at the top of the wrinkles. The dimensions immediately after disassembly are 1 after ion-exchanged water treatment for cation exchange membranes.
In the case of an anion exchange membrane, it was 103.2% after ion-exchange water treatment.

[0044]

According to the present invention, after the ion exchange membrane is converted to a regenerative type, it is set in an electrodialysis tank in a wet state. It is possible to suppress the deformation of the membrane, particularly the expansion deformation, which develops due to the ion exchange of the functional groups. As a result, there is an advantage that the generation of the ion exchange membrane, such as bending and wrinkling, can be avoided.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing one embodiment of a deionized water producing apparatus.

[Explanation of symbols]

 A: Anion exchange membrane K: Cation exchange membrane 1: Container (electrodialysis tank) 2: Anode compartment 3: Cathode compartment 4: Anode 5: Cathode S1, S2 ... Sn: Concentration compartment R1, R2 ... Rn: desalting chamber D1, D2, D3... Dn: desalting chamber frame C1, C2, C3... Cn: concentrating chamber frame N1, N2, N3. 7: Deionized water conduit 8: Concentrated liquid introduction pipe 9: Concentrated liquid conduit

Claims (5)

[Claims] 1. An ion exchanger is accommodated in a desalination chamber of an electrodialysis tank in which a cation exchange membrane and an anion exchange membrane are alternately arranged, and a desalination chamber and a concentration chamber are formed. In an apparatus for producing deionized water in which electricity is supplied while flowing water to be treated, 70% or more of ion exchange groups of a cation exchange membrane or an anion exchange membrane are incorporated into an electrodialysis tank in a wet state in a regenerative type, An apparatus for producing deionized water, wherein water is passed through an electrodialysis tank. 2. The apparatus according to claim 1, wherein the ion exchange membrane is a heterogeneous ion exchange membrane composed of ion exchange resin particles and a binder polymer. 3. The apparatus for producing deionized water according to claim 1, wherein the method for converting the cation exchange groups of the cation exchange membrane into a regenerating type is acid treatment. 4. The apparatus for producing deionized water according to claim 1, wherein the method for converting the anion exchange group of the anion exchange membrane into a regenerating type is an alkali treatment. 5. The ion exchanger housed in the desalting chamber is a porous body obtained by bonding a cation exchange resin, an anion exchange resin or a mixture thereof with a binder polymer.
5. The apparatus for producing deionized water according to any one of items 4 to 4.