JP3513955B2 - Electrodialysis type deionized water production method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing deionized water by electrodialysis. More specifically, the present invention relates to a self-regenerating type electrolysis apparatus for producing deionized water by combining an ion exchanger and an ion exchange membrane. The present invention relates to a dialysis deionized water production method.

[0002]

2. Description of the Related Art As a method for producing deionized water, a method is generally used in which water to be treated is flowed through a packed bed of ion exchange resin so that impurity ions are adsorbed by the ion exchange resin and removed to obtain deionized water. . Here, the ion exchange resin having a reduced adsorption capacity is regenerated by using an acid or an alkali. However, this method has a problem that the waste liquid of the acid or alkali used for the regeneration is discharged, and therefore a deionized water production method that does not require regeneration is desired.

From such a point of view, a self-regenerating type electrodialysis deionized water production method in which an ion exchange resin and an ion exchange membrane are combined has attracted attention in recent years. In this method, a mixture of an anion exchanger and a cation exchanger is placed in a desalting chamber of an electrodialysis device in which an anion exchange membrane and a cation exchange membrane are alternately arranged, and water to be treated is placed in the desalting chamber. It is a method of producing deionized water by applying voltage while flowing and performing electrodialysis.

Regarding this method, a method of limiting the width and thickness of the desalting chamber (Japanese Patent Laid-Open No. 61-107906) and a method of using an ion exchange resin having a uniform diameter in the desalting chamber are used. (JP-A-3-207487), a method of converting an ion exchange resin filled in a portion through which water to be treated first passes into anion exchange resin (JP-A-4-71624), and ion exchange filled in a desalting chamber. A method in which the body is a mixture of ion-exchange resin and ion-exchange fibers (Japanese Patent Application Laid-Open No. 5-27)
No. 7344) are being studied. However, since a solid cross-linked ion exchange resin is used as the ion exchanger to be put in the desalting chamber, it is crushed during use, efficient desalination and regeneration are not performed, and there is a problem in the stability of the purity of the obtained water. there were.

As a method of compensating for these drawbacks, a method of introducing a ion-exchange group by performing radiation grafting on a nonwoven fabric such as polyethylene or polypropylene (Japanese Patent Laid-Open No. 5-6472).
No. 6, JP-A-5-131120), an ion exchange polymer and a reinforcing polymer in the form of a composite fiber having a sea-island structure, and then formed into a sheet (JP-A-6-7926).
No. 8) has been proposed. In these methods, the part that retains the strength and the part that expresses the ion exchange property are divided into functions, but it is necessary to use radiation, the process of producing the conjugate fiber is complicated, and the mechanical strength is There were drawbacks, such as not always being sufficient.

[0006]

DISCLOSURE OF THE INVENTION The present invention relates to a self-regenerating type electrodialysis deionized water production method in which an ion exchanger and an ion exchange membrane are combined, and an ion having high strength regardless of complicated steps such as the use of radiation. The purpose of the present invention is to produce an exchanger and stably produce highly pure deionized water.

[0007]

SUMMARY OF THE INVENTION According to the present invention, an ion exchanger is filled in a desalting chamber of an electrodialyzer in which a cation exchange membrane and an anion exchange membrane are alternately arranged between a cathode and an anode. In the method for producing deionized water by energizing while flowing water to be treated in the deionization chamber of the deionized water producing apparatus, at least one of styrene or 4-vinylpyridine, butadiene or It is intended to provide an electrodialysis-type deionized water production method using a polymer having a structure in which an ion exchange group is introduced into a block copolymer with at least one type of isoprene or a hydrogenated product thereof.

In the present invention, a block copolymer of at least one kind of styrene or 4-vinylpyridine and at least one kind of butadiene or isoprene or a hydrogenated product thereof is used as a base material and an ion exchange group is introduced. The polymer is characterized in that an ion exchanger is molded and used in an electrodialysis type deionized water producing apparatus.
The ion exchanger used in this method is a block copolymer, and since the strength-retaining portion and the ion-exchangeable portion are shared within the molecule, the mechanical strength is high and the ion-exchange performance is also excellent. .

The above-mentioned hydrogenated product of the block polymer is a product obtained by saturating a double bond portion in the polymer by hydrogenation, and is not necessarily limited to one in which hydrogen is added to all the double bonds. I can't. By adding hydrogen, the mechanical strength can be further improved.

In the above block copolymer, the content of the monomer component containing at least one of butadiene and isoprene is preferably 20 to 90 mol% with respect to the total amount of the monomer components of the copolymer. If the content is less than 20 mol%, the mechanical strength of the ion exchanger may decrease, which is not preferable. If the content is higher than 90 mol%, the ion exchange capacity becomes low, the adsorption and desalting of ions may not be sufficiently carried out, and the electric resistance may increase, which is not preferable. When the content of the polymerized product of at least one of butadiene and isoprene or the hydrogenated product thereof is 35 to 80 mol%, the performance stability is also excellent, which is particularly preferable.

The ion exchange capacity of the ion exchanger is 0.5.
~ 4 meq / g dry resin is preferred. When the ion exchange capacity is smaller than 0.5 meq / g dry resin, the adsorption of ions is not sufficiently performed in the desalting chamber, the purity of the treated water may decrease, and the electric resistance may increase, which is not preferable. If the ion exchange capacity is larger than 4 meq / g dry resin, the strength of the ion exchanger may decrease, which is not preferable. Especially, the ion exchange capacity is 1 to 3
A milliequivalent / g dry resin is more preferable because it is excellent in desalination performance and mechanical strength, and has low electric resistance, so that treated water of high purity can be obtained at low voltage.

The shape of the ion exchanger is preferably a cloth or foam. Compared to ordinary ion exchange resins, these molded products are easier to fill when assembled in an electrodialysis tank, and because the ion exchangers are fixed in a uniformly dispersed state, ions of the same sign will be used during use. It is preferable because there is no aggregation of exchange groups and stable performance is obtained. In the case of the cloth-like material, the block copolymer may be made into a cloth-like shape and then introduced with an ion-exchange group, or the block copolymer may be made into a fiber-like shape and then introduced into a cloth-like shape. Good. In the former method of introducing an ion-exchange group after forming a cloth, it is necessary to carry out both a cation-exchange group introduction reaction and an anion-exchange group introduction reaction, and the first reaction is performed during the second reaction. The latter method is preferable because the introduced ion-exchange group may be deactivated. Also in the case of a foam, an ion exchange group may be introduced after mixing the block copolymer with a foaming agent and foam-molding, or may be foam-molding after introducing the ion exchange group into the block copolymer. However, the latter method is preferable for the same reason as the cloth-like material.

The porosity of the molded body of the ion exchanger is preferably 20 to 95% when installed in the desalting chamber. Porosity is 2
If it is less than 0%, the water in the desalting chamber is difficult to flow and the amount of treated water may decrease, which is not preferable. If the porosity is higher than 95%, the adsorption and desalting of ions may not be sufficiently performed, and the mechanical strength of the ion exchanger may be reduced, which is not preferable. Especially when the porosity is 40 to 80%,
In addition to strength and performance, performance stability is also improved, which is more preferable.

The film thickness of the molded body of the ion exchanger is preferably 0.5 to 2 mm when installed in the desalting chamber. The film thickness is 0.
If the thickness is less than 5 mm, the water in the desalting chamber is difficult to flow and the amount of treated water may decrease, which is not preferable. If the film thickness is thicker than 2 mm, the electric resistance may increase, which is not preferable.

The ion-exchange group of the ion-exchanger is mainly a sulfonic acid or its salt type, and the anion-exchange group is mainly a quaternary ammonium salt group from the viewpoints of ion adsorption and electric resistance. Alternatively, it is preferably a pyridinium base. The method for introducing the ion-exchange group into the substrate is not particularly limited, and a known method can be adopted.

Specifically, the production apparatus for producing deionized water by the production method of the present invention preferably has the following configuration. That is, a plurality of cation exchange membranes and anion exchange membranes are alternately arranged between an anode chamber having an anode and a cathode chamber having a cathode, and the anode side is partitioned by the anion exchange membrane and the cathode side is positive. About 2 to 30 sets of demineralization chambers partitioned by an ion exchange membrane and a concentration chamber partitioned by a cation exchange membrane on the cathode side and an anion exchange membrane on the anode side are alternately arranged. Desalination can be performed by flowing an electric current while flowing water to be treated in the desalting chamber and flowing water for discharging concentrated salts in the concentration chamber. Each unit cell, it is preferable to mark pressure to about 4V voltage dissociation of water occurs in the desalting compartment.

[0017]

Example 1 A styrene-butadiene block copolymer having a butadiene content of 60 mol% (TR20 manufactured by Japan Synthetic Rubber Co., Ltd.)
00) is melt-spun at a molding temperature of 200 ° C. and a fiber diameter of 50
Fibers of μm were obtained. This was used as the base material of the ion exchanger.
After cutting 100 g of the base fiber with a fiber length of about 2 cm,
Sulfonation was carried out by immersing in 1000 g of 98 wt% sulfuric acid at 60 ° C. for 8 hours, and the ion exchange capacity was 2.0.
115 g of cation exchange resin fiber of meq / g dry resin
Got Separately, 100 g of the above-mentioned base fiber is added to 2
A chloromethylation reaction was carried out by immersing the solution in 1500 g of a chloromethyl methyl ether solution containing stannous chloride in a weight percentage at 60 ° C. After the reaction, the product was washed with methanol and immersed in a methanol solution of 1N trimethylamine at 40 ° C. for 16 hours to perform an amination reaction.
117 g of anion exchange resin fiber of meq / g dry resin
Got

40 g of the above cation exchange resin fiber, 60 g of anion exchange resin fiber and 20 g of unreacted fiber
Was mixed and dispersed, and then hot roll pressed at 190 ° C. to produce a nonwoven fabric having a total ion exchange capacity of 1.5 meq / g dry resin, a porosity of 75%, a thickness of 320 μm, and a basis weight of 96 g / m ² . .

This ion-exchange nonwoven fabric was assembled in a desalting chamber of an electrodialyzer to conduct a water treatment test. Electrodialyzer
A structure in which five cation exchange membranes (manufactured by Asahi Glass Co., Ltd., trade name Selemion AMT) and four anion exchange membranes (manufactured by Asahi Glass Co., Ltd., trade name Selemion AMP) were alternately stacked was used. Water with an electric conductivity of 5 μS / cm is used as raw water,
When a desalting treatment was performed by applying a voltage of 4 V per unit cell, treated water having an electric conductivity of 0.08 μS / cm was stably obtained.

Example 2 As a base material for the ion exchanger, a styrene-hydrogenated isoprene block copolymer having a hydrogenated isoprene content of 35 mol% was used in place of the styrene-butadiene block copolymer (manufactured by Kuraray Co., Ltd.). Product name Septon 210
In the same manner as in Example 1 except that 4) was used, the total ion exchange capacity was 1.2 meq / g dry resin, the porosity was 70%,
A nonwoven fabric having a thickness of 250 μm and a basis weight of 90 g / m ² was prepared.

This ion-exchange nonwoven fabric is put in a desalting chamber,
A water treatment test was conducted in the same manner as in Example 1. When water having an electric conductivity of 5 μS / cm was used as raw water and a voltage of 4 V was applied per unit cell for desalting, the electric conductivity was 0.09 μS.
/ Cm of treated water was stably obtained.

Example 3 Tetrahydrofuran 20 dehydrated and refined under cooling in a pressure-resistant airtight container which was dried under reduced pressure at 100 ° C. and then brought to normal pressure with purified nitrogen.
00 ml, 54 g of butadiene, and 10 ml of a 1 mol / l n-butyllithium hexane solution were added, and the mixture was stirred at 35 ° C. for 2 hours for polymerization. After the polymerization, put the left 4-vinylpyridine 42g keeping the airtight state, and further polymerized for 2 hours at 40 ° C., butadiene et emissions content of 60 mol%
4-vinylpyridine-butadiene block copolymer 9
0 g was synthesized. The copolymer was melt-spun at a molding temperature of 180 ° C. to obtain fibers having a fiber diameter of 50 μm. The obtained fiber was cut to a fiber length of about 2 cm, and then immersed in a 10 wt% methyl iodide hexane solution at 35 ° C. for 8 hours to carry out a quaternary amination reaction to obtain an ion exchange capacity of 1.8 meq / 95 g of dry resin anion exchange fiber was obtained.

A styrene-butadiene block copolymer, TR2000 (manufactured by Japan Synthetic Rubber Co., Ltd.) was used in the same manner as in Example 1 to obtain an ion exchange capacity of 2.0 meq / g.
115 g of dried resin cation exchange fiber was obtained. 40 g of the above cation exchange fibers, 60 g of anion exchange fibers and 20 g of unreacted fibers were mixed and dispersed, and then hot roll press was performed at 180 ° C. to obtain a total ion exchange capacity of 1.6 meq / g.
Dry resin, porosity 75%, thickness 320 μm, basis weight 9
A 6 g / m ² non-woven fabric was prepared.

The non-woven fabric of this ion exchanger is put in a desalting chamber,
A water treatment test was conducted in the same manner as in Example 1. When water having an electric conductivity of 5 μS / cm was used as raw water and a voltage of 4 V was applied per unit cell for desalting, the electric conductivity was 0.08 μS.
/ Cm of treated water was stably obtained.

Example 4 A styrene-butadiene block copolymer having a butadiene content of 60 mol% (TR20 manufactured by Japan Synthetic Rubber Co., Ltd.)
00) 120 g is dissolved in 3600 g of chloroform,
The solution was poured into stirring methanol to cause precipitation, and the polymer was powdered. 9 g of 100 g of the obtained polymer
It was dipped in 1000 g of 8% by weight sulfuric acid at 60 ° C. for 8 hours to be sulfonated to obtain 120 g of a cation exchanger having an ion exchange capacity of 2.5 meq / g dry resin. Further, 100 g of the styrene-butadiene block copolymer was dissolved in 2000 g of chloroform, 200 g of chloromethyl methyl ether and 20 g of stannic chloride were added, and chloromethylation reaction was carried out at 40 ° C. for 16 hours. After the reaction, the polymer solution was precipitated with methanol, washed, and dried, and then the chloromethylated polymer powder was immersed in a methanol solution of 1N trimethylamine at 40 ° C. for 16 hours to perform an amination reaction to obtain an ion exchange capacity of 2.4 mm. 120 g of anion exchanger of equivalent weight / g dry resin was obtained.

40 g of the above cation exchanger powder, 60 g of anion exchanger powder and 20 g of unreacted styrene-butadiene block copolymer powder were mixed with dichlorodifluoromethane and molded by a pressure foam molding machine to obtain a total ion exchange capacity. There 2.0 meq / g dry resin, porosity 80%, thickness 1 mm, to prepare a foam sheet having a basis weight 200 g / m ^2.

The ion-exchange foam sheet was placed in a desalting chamber and a water treatment test was conducted in the same manner as in Example 1. Water with an electric conductivity of 5 μS / cm is used as raw water, and 4 per unit cell is used.
When desalting was performed by applying a voltage of V, the conductivity was 0.0
A treated water of 8 μS / cm was stably obtained.

Comparative Example 1 An ion exchange capacity of 2.0 meq / g dry resin was obtained in the same manner as in Example 1 except that polystyrene was used as the base material of the ion exchanger instead of the styrene-butadiene block copolymer. Anion exchange fiber having a cation exchange fiber and an ion exchange capacity of 1.6 meq / g dry resin was obtained. After 40 g of this cation exchange fiber, 60 g of anion exchange fiber and 20 g of unreacted fiber were mixed and dispersed, hot roll pressing was performed at 190 ° C. However, the strength was weak and a nonwoven fabric could not be produced.

The ion-exchanger fibers obtained there were mixed in the same proportion as above and put in a desalting chamber, and a water treatment test was conducted in the same manner as in Example 1. When water having an electric conductivity of 5 μS / cm was used as raw water to apply desalting by applying a voltage of 4 V per unit cell, only treated water having an electric conductivity of 0.5 μS / cm was obtained.

[0030]

INDUSTRIAL APPLICABILITY According to the electrodialysis type deionized water production method of the present invention, since the ion exchanger has high mechanical strength and excellent ion exchange performance, treated water with stable purity can be obtained. Further, this ion exchanger is easy to manufacture and does not require a particularly complicated process.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI // C08J 5/20 C02F 1/46 103 (56) References JP-A-6-79268 (JP, A) JP-A-3- 26390 (JP, A) JP 5-230130 (JP, A) JP 5-131120 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C02F 1/469 B01D 61 / 44 B01D 61/48 B01J 43/00 C02F 1/42 C08J 5/20

Claims (3)

(57) [Claims] Claim: What is claimed is: 1. A deionized water producing apparatus comprising: a desalting chamber of an electrodialysis apparatus, in which a cation exchange membrane and an anion exchange membrane are alternately arranged between a cathode and an anode, filled with an ion exchanger. In the method of producing deionized water by energizing while flowing water to be treated in a salt chamber, as the ion exchanger, at least one of styrene or 4-vinylpyridine,
An electrodialysis-type deionized water production method using a polymer having a structure in which an ion exchange group is introduced into a block copolymer with at least one of butadiene or isoprene or a hydrogenated product thereof. 2. A base material for an ion exchangerthe aboveBoth blocks
PolymerOr its hydrogenated productIn butadiene or
Is a monomer consisting of at least one of isoprenecomponent
But,As the content of the monomer component, the copolymer monomer
For the total amount of ingredients20-90 mol%ContainedRequest
Item 1DescriptionMethod for producing electrodialysis-type deionized water of. Wherein the ion exchanger is, cloth-like material or Ah <br/> Ru claim 1 or 2 electrodialysis type deionized water production method according with the foam.