JPH08197063A - Apparatus for producing deionized water - Google Patents

Abstract

PURPOSE: To stably obtain deionized water in an apparatus for producing deionized water obtd. by housing an ion exchanger in each desalting chamber of an electrodialysis vessel with cation exchange membranes and anion exchange membranes alternately arranged between the cathode and anode. CONSTITUTION: A membraneous porous material made of polyolefin or polyfluoroolefin is sulfonated or chlorosulfonated, a soln. of an anion exchange polymer is impregnated into the porous material to carry the polymer and the resultant material is used as an ion exchanger.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for producing deionized water, and more specifically, an apparatus for producing deionized water of a self-regeneration type which produces deionized water by combining an ion exchanger and an ion exchange membrane. It is about.

[0002]

2. Description of the Related Art As a method for producing deionized water, water to be treated is flowed through a packed bed of ion exchange resin to remove impurity ions by adsorbing and removing the impurity ions on the ion exchange resin. A method of regenerating an ion exchange resin having a reduced adsorption capacity with an acid or an alkali is widely used. However, this method has a problem that the waste liquid of the acid or alkali used for the regeneration is discharged, and therefore a method for producing deionized water 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 recently attracted attention. 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) or a method of using an ion exchange resin having a uniform diameter in the desalting chamber (special feature) Kaihei 3-207487), a method in which the ion exchange resin filled in the portion through which the water to be treated first passes is anion exchange resin (Japanese Patent Laid-Open No. 4-71624), and the ion exchanger filled in the desalting chamber is the ion exchange resin. A method of forming a mixture of ion exchange fibers (Japanese Patent Laid-Open No. 5-277344) has been studied, but when an ion exchange resin is used as an ion exchanger to be placed in the desalting chamber, the surface area is small,
There was a problem in the stability of the purity of the obtained water because efficient desalting and regeneration were not performed.

When ion-exchange fibers are used as the ion-exchanger in the desalting chamber, they have insufficient mechanical strength and are crushed when operated for a long time, or the cation-exchange fibers and the anion-exchange fibers are dispersed unevenly. There was a drawback that the purity of water obtained by liquefying becomes unstable. Further, even these mixtures have the same problem.

As a method for 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. 5-64).
726, JP-A-5-131120), and a sheet-shaped composite fiber of an ion exchange polymer and a reinforcing polymer, which is then formed into a sheet (JP-A-6-79268). There is a drawback in that a uniform ion exchanger cannot be obtained easily and stably, because the process of using radiation or the process of producing a composite fiber is complicated.

An object of the present invention is to solve the above-mentioned drawbacks of the prior art, and to provide a deionized water producing apparatus capable of stably obtaining deionized water.

[0008]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an electrical structure in which a cation exchange membrane and an anion exchange membrane are alternately arranged between a cathode and an anode. In a deionized water production apparatus in which a deionization chamber of a dialysis tank contains an ion exchanger, the ion exchanger is sulfonated or chlorosulfonated from a membrane-like porous material made of polyolefin or polyfluoroolefin, The present invention provides a deionized water production apparatus in which an anion-exchangeable polymer solution is impregnated with and an anion-exchangeable polymer is supported.

In the present invention, polyolefin or polyfluoroolefin is used as the porous material. In the desalination chamber of the deionized water production equipment, water dissociation occurs simultaneously with desalination to generate acid and alkali to regenerate the ion exchanger, so it is necessary to select a material with excellent acid and alkali resistance. From this viewpoint, the above materials are preferably used.

The porous material composed of polyolefin or polyfluoroolefin used in the present invention includes:
For example, polyethylene, polypropylene, poly-4-methylpentene-1, polyvinylidene fluoride, polytetrafluoroethylene, hexafluoropropylene / tetrafluoroethylene copolymer, fluoroolefin-based monomer / olefin-based monomer copolymer and the like can be mentioned. However, polyethylene, polypropylene, polyethylene / polytetrafluoroethylene copolymer, polyvinylidene fluoride, and mixtures thereof are preferable materials from the viewpoint of reactivity, moldability, film strength and the like.

The porous material of the present invention is in the form of an ion exchanger into which an ion exchange group is introduced, and its porosity is 20 to 95 when it is stored or filled in the desalting chamber.
%, Especially 30 to 90%, and particularly 40 to 80% is preferable. If the porosity is lower than 20%, the water in the desalting chamber will not flow easily and the amount of treated water will be reduced. If the porosity is higher than 95%, adsorption of ions and desalting will not be sufficiently carried out, and the electrical resistance of the desalting chamber will also increase. Not preferable. When the porosity is 30 to 90%, a high treated water purity can be obtained, and when it is 40 to 80%, the performance stability is also excellent, which is preferable.

The porous material is in the form of an ion exchanger into which an ion exchange group is introduced, and the film thickness of the porous material is 0.1 to 10 mm when accommodated in the desalting chamber, and particularly 0.3. ~
It is preferably 5 mm, particularly 0.5 to 2 mm. If the film thickness is less than 0.1 mm, the film strength will decrease, and if it is more than 10 mm, the electrical resistance of the desalting chamber will increase, which is not preferable.
When the film thickness is 0.3 to 5 mm, both film strength and resistance are satisfied, and when it is 0.5 to 2 mm, durability and performance stability are excellent, which is preferable.

Examples of the method for sulfonation or chlorosulfonation of the porous material include a method using concentrated sulfuric acid, a method using chlorosulfonic acid and a method using a triethyl phosphate / sulfuric acid anhydride complex. .

The ion exchange capacity of the cation exchange groups of the sulfonated or chlorosulfonated porous material is 0.5.
~ 4 meq / g dry resin, especially 1-3 meq / g
A dry resin is preferably used. If the ion exchange capacity is smaller than 0.5 meq / g dry resin, the adsorption of ions is not sufficiently carried out in the desalting chamber, the purity of the treated water is lowered, and the electric resistance is increased, which is not preferable. If the ion exchange capacity is larger than 4 meq / g dry resin, the strength of the porous material is significantly reduced and it is crushed during use, which is not preferable. It is preferable that the ion exchange capacity is 1 to 3 meq / g dry resin because the desalination performance is excellent and the electric resistance is low, and thus treated water with high purity can be obtained at low voltage.

Examples of the anion exchange polymer include polyethyleneimine, poly (vinylbenzyltrimethylammonium chloride), poly (4-vinylpyridine), and quaternary compounds thereof, poly (acrylamide),
Poly (N, N-dimethylacrylamide) and its quaternized product, poly (N, N-dimethylaminopropylacrylamide) and its quaternized product, poly (dimethylaminoethyl acrylate), and its quaternized product , Poly (N-isopropylacrylamide), poly (2-hydroxy-3-dimethylaminopropyl chloride), etc.,
Any substance can be used as long as it can be dissolved in a solvent to form a solution. Among them, poly (vinylbenzyltrimethylammonium chloride), poly (2-hydroxy-3-dimethylaminopropyl chloride), poly (4-vinylpyridine)
Polymers having a quaternary ammonium salt group or a pyridinium salt group such as the quaternary compound are preferable because they have strong basicity and are excellent in anion exchange characteristics and electric resistance. The anion exchange polymer has an ion exchange capacity of 1 milliequivalent / g dry resin or more, preferably 3 to 9 equivalents / g dry resin, from the viewpoint of anion adsorption and electric resistance.

The ion exchanger used in the present invention is prepared by introducing a sulfonic acid group or a chlorosulfonic acid group as a cation exchange group into a membrane-like porous material, and then using the anion exchange polymer as described above. The porous material is impregnated with the anion-exchangeable polymer by dipping or coating in a solution, and preferably dried. By doing so, a part of the anion-exchange groups contained in the anion-exchange polymer form an ion complex with the cation-exchange groups contained in the porous material. In this way, the anion-exchangeable polymer is physically and chemically fixed to the porous material,
It will be firmly supported.

The cation exchange membrane and the anion exchange membrane used in the deionized water producing apparatus of the present invention are not particularly limited,
Either one can be used. As the cation exchange membrane, it is preferable to use a strong acid type cation exchange membrane that can be used even in an acidic environment. As the anion exchange membrane, it is preferable to use a strong base type anion exchange membrane that can be used even in an alkaline environment. The thickness of the cation exchange membrane and the anion exchange membrane can be used in the range of 5 to 500 μm, but from the viewpoint of membrane strength and membrane resistance, it is preferably 1.00 to 300 μm.

As the other points of the deionized water producing apparatus of the present invention, known ones described in, for example, JP-A-3-224688 can be widely used.

[0019]

EXAMPLES The present invention will now be described with reference to examples, but the present invention is not limited to these examples.

<Example 1> A foamed polyethylene sheet having a porosity of 95% and a thickness of 4 mm was added to 98% concentrated sulfuric acid at 60 ° C and 16 ° C.
It was immersed for a period of time for sulfonation. The ion exchange capacity of the obtained cation exchanger was 1.2 meq / g dry resin. 30% of this cation exchanger was added to a 2% aqueous solution of poly (2-hydroxy-3-dimethylaminopropyl chloride) (ion exchange capacity 7.2 meq / g dry resin).
After being immersed at 16 ° C. for 16 hours, it was washed with water and dried to obtain an ion exchanger.

The obtained 4 mm thick ion exchanger was compressed and placed in a 0.75 mm thick desalting chamber, and a cation exchange membrane: Selemion CMT (manufactured by Asahi Glass Co., Ltd., a strongly acidic cation exchange membrane (Trade name) and anion exchange membrane: electrodialysis tank using Selemion AMT (trade name of strong basic anion exchange membrane manufactured by Asahi Glass Co., Ltd.) (effective membrane area 500 cm ² × 5)
A pair of deionized water production equipment was assembled. The porosity of this ion exchanger in the desalting chamber is 73%. In such a deionized water production device, the raw water has an electric conductivity of 5 μm.
When S / cm of water was supplied and a voltage of 4 V was applied per unit cell for desalination, the conductivity was 0.12 μS.
/ Cm of treated water was obtained.

<Example 2> 15% of a non-woven fabric of polyethylene / polypropylene mixture having a porosity of 95% and a thickness of 5 mm
Chlorosulfonation was carried out by immersing in a 1,1,2,2-tetrachloroethane solution of chlorosulfonic acid at 25 ° C for 16 hours. After washing with methanol and washing with water, it was immersed in a 1N aqueous sodium hydroxide solution at 60 ° C. for 16 hours and further immersed in 1N hydrochloric acid at 60 ° C. for 16 hours to obtain a sulfonic acid type cation exchanger. The ion exchange capacity of the obtained cation exchanger was 1.5 meq / g dry resin. This cation exchanger was immersed in a 2% aqueous solution of poly (4-vinylpyridine) methyl iodide quaternary compound (ion exchange capacity 4.0 meq / g dry resin) at 30 ° C. for 16 hours, washed with water and dried. It was used as an ion exchanger.

Deionization consisting of an electrodialysis tank constructed in the same manner as in Example 1 except that the thickness of the obtained ion exchanger having a thickness of 5 mm was compressed and placed in a desalting chamber having a thickness of 0.75 mm. The water production equipment was assembled. The porosity of this ion exchanger in the desalting chamber is 73%. Water having an electric conductivity of 5 μS / cm was supplied as raw water to the deionized water producing apparatus, and a voltage of 4 V was applied per unit cell in the same manner as in Example 1 to perform desalination, and an electric conductivity of 0.1 μS was obtained.
/ Cm of treated water was stably obtained.

<Example 3> In a 1 liter flask, 1,
400 ml of 1,2-trichloroethane and 56.2 g of triethyl phosphate were added. 60% S after ice cooling
82.4 g of fuming sulfuric acid of O ₃ was gradually added dropwise to prepare a triethyl phosphate / SO ₃ complex.

A non-woven fabric of polyethylene / polypropylene mixture having a porosity of 96% and a thickness of 5 mm was added to the above-mentioned complex solution.
It was immersed at 16 ° C for 16 hours for sulfonation. Methano
After washing with water and washing with water, a sulfonic acid type cation exchanger was obtained. The ion exchange capacity of the obtained cation exchanger was 1.6.
It was a meq / g dry resin. The cation exchanger was immersed in a 2% aqueous solution of poly (vinyltrimethylammonium chloride) (ion exchange capacity of 4.7 meq / g dry resin) at 30 ° C. for 16 hours, washed with water and dried to give an ion exchanger.

The thickness of the obtained ion exchanger having a thickness of 5 mm was compressed and placed in a desalting chamber having a thickness of 0.75 mm.
A deionized water production apparatus composed of an electrodialysis tank constructed in the same manner as in Example 1 was assembled. The porosity of this ion exchanger in the desalting chamber is 73%. Water having an electric conductivity of 5 μS / cm was supplied as raw water to the deionized water producing apparatus, and a voltage of 4 V was applied per unit cell in the same manner as in Example 1 to carry out desalination, and an electric conductivity of 0.1 μ was obtained.
S / cm treated water was stably obtained.

Comparative Example 1 Polystyrene fiber was used in Example 3
Sulfonation was carried out by immersing the solution in the triethyl phosphate / SO ₃ complex used in Step 16 at 25 ° C. for 16 hours. After washing with methanol, it was washed with water to obtain a sulfonic acid type cation exchange fiber. The ion exchange capacity of the obtained cation exchange fiber was 2.5 meq / g dry resin. On the other hand, the same polystyrene fiber as used above is used in the form of 1,1,2,2-tetrachloroethane / octane / chloromethylmethyl ether / stannic chloride = 50/50/25 / 0.1 (parts by weight).
Chloromethylation was carried out by immersing in the solution at 30 ° C. for 16 hours. After washing with methanol, it was immersed in a 1N solution of trimethylamine in methanol at 60 ° C. for 16 hours to introduce a quaternary ammonium salt group to obtain an anion exchange fiber. The ion exchange capacity of the obtained anion exchange fiber is 2.0 meq /
g dry resin.

These ion exchange fibers were cut into about 1 cm, and cation exchange fiber / anion exchange fiber = 45/5.
A deionized water producing apparatus composed of an electrodialysis tank configured in the same manner as in Example 1 was assembled except that the mixture was mixed at a ratio of 5 (weight ratio) and then placed in a desalting chamber. The porosity of this ion exchanger in the state of being placed in the desalting chamber is 60%. Water having an electric conductivity of 5 μS / cm was supplied as raw water to the deionized water producing apparatus, and a voltage of 4 V was applied per unit cell in the same manner as in Example 1 to perform desalination, and the electric conductivity was 1 μS / cm.
Only cm of treated water was obtained.

Comparative Example 2 Example 3 is the same as Example 3 except that the anion exchange polymer prepared by grinding the anion exchange fiber of Comparative Example 1 and dispersing it in water is used as the anion exchange polymer. A deionized water production apparatus was assembled in the same manner as in. Water having a conductivity of 5 μS / cm was supplied as raw water, and a voltage of 4 V was applied per unit cell in the same manner as in Example 1 to perform desalination, and a conductivity of 2.5 μm was obtained.
Only treated water of S / cm was obtained.

[0030]

EFFECT OF THE INVENTION In the deionized water producing apparatus of the present invention, an electrodialysis tank containing an ion exchanger in which a cation exchange group and an anion exchange group are firmly fixed or supported on a membrane-like porous material. Since the electrodialysis tank has a simple structure and can be easily manufactured, and the performance of the ion exchanger is homogeneous and stable, deionized water having a stable purity can be obtained.

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Claims (6)

[Claims] 1. A deionized water producing apparatus in which an ion exchanger is housed in a desalting chamber of an electrodialysis tank in which a cation exchange membrane and an anion exchange membrane are alternately arranged between a cathode and an anode. After sulfonation or chlorosulfonation of a film-like porous material whose ion exchanger is made of polyolefin or polyfluoroolefin, it is impregnated with an anion exchange polymer solution to support the anion exchange polymer. A deionized water manufacturing device characterized by being 2. The deionized water producing apparatus according to claim 1, wherein the ion exchanger has a porosity of 20 to 95% in a state of being accommodated in the desalting chamber. 3. The deionized water producing apparatus according to claim 1, wherein the film thickness of the ion exchanger is 0.1 to 10 mm when the ion exchanger is housed in the deionization chamber. 4. The deionized product according to claim 1, 2 or 3, wherein the sulfonated or chlorosulfonated porous material has an ion exchange capacity of 0.5 to 4 meq / g dry resin. Ion water production equipment. 5. An apparatus for producing deionized water according to claim 1, wherein the anion-exchangeable polymer has an ion exchange capacity of 1.0 meq / g dry resin or more. 6. The deionized water producing apparatus according to claim 1, wherein the anion exchange group of the anion exchange polymer is a quaternary ammonium base or a pyridinium base.