JP3800706B2 - Deionized water production equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a deionized water production apparatus for producing pure water or ultrapure water used for pharmaceutical production, semiconductor production, boiler water for power generation and the like.
[0002]
[Prior art]
As a method for producing deionized water, a general method is to obtain deionized water by flowing water to be treated through a packed bed of ion exchange resin and adsorbing and removing impurity ions on the ion exchange resin. Here, a method of regenerating the ion exchange resin having reduced adsorption capacity using an acid or alkali is employed. However, this method has a problem that the waste liquid of acid and alkali used for regeneration is discharged, and therefore, a deionized water production method that does not require regeneration is desired.
[0003]
From such a viewpoint, in recent years, a self-regenerating electrodialysis deionized water production method combining an ion exchange resin and an ion exchange membrane has attracted attention. In this method, a mixture of an anion exchanger and a cation exchanger is placed in a desalting chamber of an electrodialysis apparatus 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. This is a method for producing deionized water by applying voltage while flowing and performing electrodialysis. In this method, since the ion exchange resin in a wet state is generally contained in the desalting chamber, the adhesion between the ion exchange resins or between the ion exchange resin and the ion exchange membrane is insufficient, and the thickness of the desalting chamber is increased. However, there is a drawback in that the resistance increases when trying to reduce the membrane use area.
[0004]
As a method for compensating for these drawbacks, in Japanese Patent Publication No. 4-72567 and Japanese Patent Publication No. 6-20513, the width of the desalting chamber is about 0.762 to 10.16 cm (≈0.3 to 4 inches), It has been proposed that the thickness be about 0.127 to 0.635 cm (≈0.05 to 0.25 inch) to prevent an increase in resistance. However, in this method, since the thickness of the desalting chamber is thin, it is difficult to fill the ion-exchanger into the desalting chamber, and the amount of produced water per unit area is low.
[0005]
[Problems to be solved by the invention]
The present invention relates to a self-regenerative electrodialysis deionized water production apparatus that combines an ion exchanger and an ion exchange membrane, and does not increase in resistance even if the thickness of the desalting chamber is increased, and the prior art has Another object of the present invention is to provide a deionized water production apparatus that does not have the above-described drawbacks and can stably obtain pure water over a long period of time.
[0006]
[Means for Solving the Problems]
In the present invention, a cation exchange membrane and an anion exchange membrane are alternately arranged between a cathode and an anode, and an ion exchanger is accommodated in a desalting chamber of an electrodialysis tank in which a desalting chamber and a concentration chamber are formed. In the deionized water production apparatus as described above, 0.1-20 kg / cm between the ion exchanger accommodated in the desalting chamber and the cation exchange membrane and the anion exchange membrane partitioning the desalting chamber. ² The deionized water production apparatus is characterized in that the pressure is generated.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
In the present invention, the state of the ion exchanger is changed in advance and accommodated in the desalting chamber of the electrodialysis tank, or the state is changed after being accommodated in the desalting chamber. Hereinafter, in this specification, the state of the ion exchanger will be described by the following terms. The “use state” is a state when the ion exchanger is accommodated in the desalting chamber and used for electrodialysis, and is in a state of being balanced with the environment at the time of use. The “contracted state” refers to a state in which the apparent volume of the ion exchanger is contracted by some method. “Free state” refers to a state that is in equilibrium with the environment in which it is used but is not constrained by a desalting chamber.
[0008]
In the present invention, the thickness of the desalting chamber is 0.2 cm or more, preferably 0.7 cm or more. If the thickness of the desalting chamber is less than 0.2 cm, the effect of reducing the area of the membrane used is not clear, and it is difficult to fill the ion exchanger, which is not preferable. On the other hand, if the thickness exceeds 80.0 cm, the effect of reducing the area of the film used is large, but it is also not preferable because the increase in resistance is also large. Especially, it is especially preferable that the thickness of the desalting chamber is 1.1 cm or more and 30.0 cm or less because the resistance increase is small and the effect of reducing the area of the membrane used is large.
[0009]
The pressure generated between the ion exchanger accommodated or filled in the desalting chamber and the cation exchange membrane and anion exchange membrane partitioning the desalting chamber is 0.1-20 kg / cm. ² Range. The pressure is 0.1 kg / cm ² If it is less than 1, the adhesion between the ion exchangers or between the ion exchanger and the ion exchange membrane is not sufficient, the resistance is increased, a short path of treated water can be formed, and the purity of the water obtained is not preferable. . On the other hand, the pressure is 20 kg / cm. ² If it is larger, the adhesion between the ion exchangers or between the ion exchanger and the ion exchange membrane is sufficient, but it is not preferable because the amount of treated water decreases or the ion exchange membrane used is damaged. Above all, the pressure is 0.5-10 kg / cm. ² Especially 0.8-2kg / cm ² Is preferred.
[0010]
In the present invention, as a preferable means for generating pressure between the packing body filled in the desalting chamber and the ion exchange membrane, (1) the volume of the ion exchanger accommodated in the desalting chamber is smaller than that of the regenerative type. The ion exchanger in a free state is stored in the desalting chamber with a volume of the ion exchanger regeneration type larger than that of the desalting chamber, and the ion exchanger is made to pass water and energize. And (2) means for increasing the pressure by accommodating the ion exchanger in the desalting chamber and mechanically reducing the volume of the desalting chamber.
[0011]
In the means of (1) above, the ion exchanger accommodated in the desalting chamber is It is converted into a form in which the volume is reduced from the volume of the ion exchanger in use, and is in equilibrium with that used for electrodialysis, but is not restricted by the desalination chamber Ion exchanger in state of Desalination chamber when converted to volume of It is preferable to accommodate an amount of 103 to 170% with respect to the volume. If this amount is less than 103%, the adhesion of the accommodated ion exchanger is not good, which is not preferable. On the other hand, when the amount is larger than 170%, the adhesion is good, but the pressure loss when water is passed increases, which is not preferable. In particular, the amount of the ion exchanger is particularly preferably 111 to 150%.
[0012]
As a method of reducing the volume of the ion exchanger from that of the regenerative type, (1) a method of reducing the moisture content by drying, or (2) a method of changing the counter ion to a non-regenerative type and making it a load type , (3) or a method of substituting the solvent by immersing it in an organic solvent. (4) The method of (1) in which the moisture content is reduced by drying and the load type by changing the counter ion to an ion species other than the regeneration type. The method (2) that is used in combination is a preferred method because it can be easily applied regardless of the type and structure of the ion exchanger and has a large volume increasing effect.
[0013]
When the moisture content is reduced by drying, the moisture content (weight) is preferably reduced to 1 to 30%. If the moisture content is less than 1%, drying takes time, which is not preferable. If the moisture content is greater than 30%, the effect of increasing the volume is reduced when water is passed through and energized, such being undesirable. A moisture content of 5 to 15% is particularly preferable because drying is easy and the effect of increasing the volume during water flow and energization is large. As the type of counter ion at the time of drying, Na type is preferable in the case of a cation exchanger, and Cl type is preferable in the case of an anion exchanger because it is thermally stable. The drying temperature is preferably 30 to 80 ° C. If the temperature is less than 30 ° C., drying takes time, and if the temperature is higher than 80 ° C., the ion exchange group is decomposed, which is not preferable.
[0014]
In the case of a method in which the counter ion is changed to an ion species other than the regenerative type to make it a load type, the Na type is particularly preferable for the cation exchanger and the Cl type is particularly preferable for the anion exchanger as described above. In addition, in the case of a cation exchanger, K type and Li type, and in the case of an anion exchanger, NO _Three A monovalent counter ion such as a mold is preferably used. In this respect, Ca type, Al type, SO _Four In the case of a divalent or higher counter ion such as a mold, it is not preferable because it cannot be easily converted to a regenerated form.
[0015]
Next, in the method (2) in which the ion exchanger is accommodated in the desalting chamber and the pressure is increased by mechanically reducing the volume of the desalting chamber, the chamber between the desalting chamber and the ion exchange membrane is used. It is preferable to reduce the volume of the desalting chamber by 5 to 60% by volume by introducing a spacer that contracts due to pressure, filling the ion exchanger, and compressing by applying pressure from the outside. If the desalting chamber volume to be reduced is less than 5% by volume, the adhesion of the accommodated ion exchanger is not good, which is not preferable. On the other hand, if the volume of the desalting chamber to be reduced is larger than 60% by volume, the adhesion is good, but the pressure loss when water is passed increases, which is not preferable. As the material for the shrinking spacer, a foamed sheet of polyethylene, polypropylene, polystyrene or the like is preferably used.
[0016]
In the present invention, examples of the ion exchanger accommodated in the desalting chamber include ion exchange resins, ion exchange fibers, processed products thereof, and the like. The ion exchange resin and the ion exchange resin are formed into a sheet using a binder polymer. The porous ion exchanger adhered to is a preferable ion exchanger from the viewpoints of ion exchange performance and durability. In particular, a porous ion exchanger sheet is preferable because it has good adhesion between ion exchange resins and can be easily accommodated in a desalting chamber.
[0017]
As for the porosity when the ion exchanger is accommodated in the desalting chamber, the continuous porosity involved in the passage of the liquid is preferably 5% by volume or more. If the porosity 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%, water permeability is good, desalting performance is excellent, and treated water with high purity is particularly preferable. In addition, this porosity is a value at the time of accommodating an ion exchanger in a desalting chamber, water flow, and electricity supply.
[0018]
As the ion exchanger, at least a cation exchanger, an anion exchanger, a mixture thereof, or a porous molded product thereof can be used. Moreover, the structure which combined the domain (area | region) of the cation exchanger and the domain (area | region) of the anion exchanger may be sufficient. In this case, various shapes can be used for each domain in contact with the ion exchange membrane. For example, a sea island shape, a layer shape, a mosaic shape, a lattice shape, or the like can be used. In particular, sea islands and layers are preferred because they can be easily stored in the dilution chamber and can be efficiently desalted. However, the ratio of the cation exchanger to the anion exchanger used as a whole may be a ratio of the cation exchanger / anion exchanger = 20/80 to 80/20 in the total ion exchange capacity ratio. preferable.
[0019]
When a porous ion exchanger is used as the ion exchanger, the weight fraction of the binder polymer is preferably 20% or less. If the weight fraction is larger than 20%, the surface of the ion exchange resin particles is covered with a binder polymer, so that the adsorptivity is lowered, and the porosity is lowered, so that the flow rate of the liquid to be treated is reduced and the pressure loss is increased. Absent. Among these, the weight fraction is preferably 1 to 5%. The binder polymer is preferably a thermoplastic polymer or a solvent-soluble polymer from the viewpoint of the production method of the porous ion exchanger.
[0020]
As such a binder polymer, the following can be preferably used. First, examples of the thermoplastic polymer include low density polyethylene, linear low density polyethylene, ultra high molecular weight high density polyethylene, polypropylene, polyisobutylene, 1,2-polybutadiene, vinyl acetate, ethylene-vinyl acetate copolymer, and solvent. Examples of the soluble polymer include natural rubber, butyl rubber, polyisoprene, polychloroprene, styrene-butadiene rubber, nitrile rubber, vinyl chloride-fatty acid vinyl ester copolymer, and the like.
[0021]
The thickness of the porous sheet in which the ion exchange resin is bound using the binder polymer is 50% to 100% of the thickness of the desalting chamber when the porous sheet is accommodated in the desalting chamber in a reduced volume form. preferable. If this thickness is less than 50% of the desalting chamber thickness, it is not preferable because it does not adhere to the ion exchange membrane when water is passed through or energized. If the thickness is greater than 100%, it cannot be accommodated in the desalting chamber, which is not preferable. It is particularly preferable when the thickness of the porous sheet with the volume reduced is 70 to 90% of the thickness of the desalting chamber.
[0022]
The following method is preferred as a method for binding an ion exchange resin to a porous sheet using a binder polymer. (1) A method in which ion exchange resin particles and a binder polymer are kneaded with heat and then formed into a sheet by thermoforming such as a flat plate press. (2) The binder polymer solution is applied to the surface of the ion exchange resin particles and the solvent is evaporated. (3) A method of extracting a pore-forming agent after heat-mixing and molding a binder polymer and a pore-forming agent and ion-exchange resin particles, and (4) a binder polymer solution in which the pore-forming agent is dispersed is an ion-exchange resin. For example, a method of extracting a pore-forming agent after being applied to the particle surface and cured. Among these, (1) the ion exchange resin particles and binder polymer are heat-kneaded and then formed into a sheet by thermoforming such as a flat plate press, and the binder polymer, pore former and ion exchange resin particles of (3) are heated. The method of extracting the pore-forming agent after the mixed molding is preferable from the viewpoints of molding processability and specific resistance of the resulting porous ion exchanger.
[0023]
The ion exchange group of the ion exchanger has a sulfonic acid type that is a strong acid as a cation exchange group, and a quaternary ammonium salt type or a pyridinium salt type that is a strong base as an anion exchange group. It is preferable from the viewpoint of stability. The ion exchange capacity of the ion exchanger is preferably 0.5 to 7 meq / g dry resin. If the ion exchange capacity is lower than 0.5 meq / g dry resin, ion adsorption and desalting are not sufficiently performed in the desalting chamber, and the purity of the treated water may be lowered, which is not preferable. In the case where the ion exchange capacity is 1 to 5 meq / g dry resin, a product with high treated water purity is obtained, and the performance stability is excellent, which is particularly preferable.
[0024]
As an apparatus for producing deionized water in the present invention, for example, JP-A-3-186400, JP-A-2-277526, JP-A-5-64726, US Pat. No. 4,632,745 and US Pat. It is preferable to use an electrodialysis tank having the following configuration, which is described in the specification of US Pat. No. 5,425,866. In the electrodialysis tank, a plurality of cation exchange membranes and anion exchange membranes are preferably arranged alternately through a chamber frame between an anode chamber having an anode and a cathode chamber having a cathode, and the anode side is A desalting chamber partitioned by an anion exchange membrane and a cathode side partitioned by a cation exchange membrane, and a concentration chamber partitioned by a cation exchange membrane on the cathode side and partitioned by an anion exchange membrane are preferred alternately. 2 to 50 sets are formed. The thickness of the frame-like chamber frame having an opening at the center interposed between the cation exchange membrane and the anion exchange membrane defines the thickness of the desalting chamber and the concentration chamber. The thickness of the chamber frame of the desalting chamber and the concentration chamber is not necessarily the same. The ion exchange membrane can be either homogeneous or heterogeneous, and can be reinforced with a woven or non-woven fabric in order to increase the mechanical strength. In order to keep the thickness of the concentrating chamber at a predetermined thickness, a net-like spacer (spacer) is preferably inserted and arranged. Desalination can be performed by flowing the water to be treated in the desalting chamber and flowing an electric current in the concentration chamber while flowing water for discharging the concentrated salts. A voltage of about 4 to 20 V is preferably applied to each unit cell, and the current density is preferably 0.00001 to 0.05 A / cm. ² Is energized.
[0025]
FIG. 1 is a diagram schematically showing an example of the seed electrodialysis tank. In FIG. 1, A is an anion exchange membrane and K is a cation exchange membrane. As shown in the drawing, both the ion exchange membrane A and the cation exchange membrane K are disposed in the desalination chamber frame D in the electrodialysis tank 1. ₁ , D ₂ , D _Three ... Dn and concentration chamber frame C ₁ , C ₂ , C _Three ... Arranged at predetermined intervals via Cn, whereby anode chamber 2 and concentrating chamber S ₁ , S ₂ ... Sn, desalination chamber R ₁ , R ₂ ... Rn and cathode chamber 3 are formed. And desalination chamber R ₁ , R ₂ ... Rn is filled with Yin Yang ion exchange resin. Spacer N in the concentration chamber ₁ , N ₂ , N _Three ... Nn is inserted and arranged.
[0026]
In FIG. 1, reference numeral 4 denotes an anode, and 5 denotes a cathode, and a predetermined voltage is applied between both electrodes during operation. As a result, the desalination chamber R from the conduit 6 ₁ , R ₂ ... Anion components in the liquid to be treated introduced into Rn permeate and transfer through the anion exchange membrane A to the concentration chamber on the anode side, while cation components in the liquid to be treated pass through the cation exchange membrane K to the cathode. Permeated to the concentration chamber on the side, the liquid to be treated itself is deionized and discharged through the conduit 7. Further, the concentrated liquid passes through the introduction pipe 8 to each concentration chamber S. ₁ , S ₂ ... Are introduced into Sn, where the positive and negative ions permeated as described above are collected and discharged from the conduit 9 as a concentrate.
[0027]
The cations in the water to be treated that are captured by the cation exchanger in the desalting chamber are given a driving force by an electric field, and are exchanged via the cation exchanger in contact with the captured cation exchanger. It reaches the membrane and passes through the membrane and moves to the concentration chamber. Similarly, the anion in the water to be treated captured by the anion exchanger moves to the concentration chamber via the anion exchanger and the anion exchange membrane. For this reason, if the cation exchanger and the anion exchanger are gathered within a certain range to form an aggregation region, the number of contact points between the same kind of ion particles is remarkably increased, so that the movement of ions is facilitated. Since ion performance improves, it is further more preferable.
[0028]
【Example】
EXAMPLES Hereinafter, although this invention is demonstrated in more detail based on an Example, of course, this invention is not limited to these Examples.
[0029]
Example 1
A sulfonic acid type (H type) cation exchange resin (trade name: 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 dry resin, and A quaternary ammonium salt type (OH type) anion exchange resin (trade name: Diaion SA-10A, manufactured by Mitsubishi Chemical Corporation) having a particle size of 400 to 600 μm and an ion exchange capacity of 3.5 meq / g dry resin. After drying with hot air at a temperature of 50 ° C. to a moisture content of 8% by weight, the mixture was mixed at a cation exchange resin / anion exchange resin = 44/56 (weight ratio in the dry state), and the ion exchange capacity ratio was 50 / 50 mixture.
[0030]
This dry ion exchange resin mixture was filled in a desalting chamber of a vertical electrodialysis tank having a desalting chamber thickness of 1.2 cm and a concentrating chamber thickness of 0.2 cm at a volume filling rate of 60 minutes. When the specific resistance in 10 μS / cm water was measured after water and 24 hours pre-energization treatment, the current density was 0.0025 A / cm. ² At that time, it was 1051 Ω · cm. Using such an electrodialysis tank, deionized water was produced as follows. Electrodialysis tanks are cation exchange membranes (strongly acidic heterogeneous membrane, thickness 500 μm, ion exchange capacity 4.5 meq / g dry resin) and anion exchange membranes (strongly basic heterogeneous membrane, thickness 500 μm, ion exchange capacity) 3.5 milliequivalent / gram dry resin) was placed through a desalting chamber frame (made of polypropylene with a thickness of 1.2 cm) and concentrated chamber frame (made of polypropylene with a thickness of 0.2 cm) and tightened, and the filter press type dialysis tank ( An effective area of 507 cm consisting of a polypropylene net with an intersection thickness of 0.2 cm is inserted into the concentration chamber. ² (13 cm wide, 39 cm long) × 5 pairs were used.
[0031]
Water having an electric conductivity of 5 μS / cm is used as raw water, and the current density is 0.004 A / cm. ² When desalting was carried out at a voltage of 5 V per unit cell, the treated water with a conductivity of 0.062 μS / cm was 0.4 m. ^Three It was stably obtained at a production rate of / h. In this case, 1m of production water ^Three Effective area of membrane used per 1h is 1.27m ² Met. After the measurement, the ion exchange resin in the desalting chamber was taken out, and the volume of the ion exchange resin mixture in the free state was measured to be 122% of the volume of the desalting chamber. Moreover, when the measurement apparatus shown in FIG. 2 was used, the same dry ion exchanger as in this example was put into the metal container 10 shown in FIG. 2 at the same volume filling rate, and the generated pressure was measured by passing water. 2.1kg / cm ² Met. In FIG. 2, 11 is a metal plate, 12 is a water inlet, 13 is a water outlet, 14 is a load cell, and 15 is a dry ion exchanger.
[0032]
Example 2
Sodium sulfonate type (Na type) cation exchange resin (trade name: 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 dry resin, and A quaternary ammonium salt type (Cl type) anion exchange resin (product name: Diaion SA-10A, manufactured by Mitsubishi Chemical Corporation) having a particle size of 400 to 600 μm and an ion exchange capacity of 3.5 meq / g dry resin. After drying with hot air at a temperature of 50 ° C. to a moisture content of 8% by weight, mixing is carried out at a cation exchange resin / anion exchange resin = 44/56 (weight ratio in the dry state), and the ion exchange capacity ratio is 50/50 A mixture of
[0033]
3% by weight of linear low density polyethylene (manufactured by Dow Chemical Company, trade name: Affinity SM-1300) was mixed with this mixture and kneaded at a temperature of 120 to 130 ° C. The obtained kneaded material was thermoformed at a temperature of 130 ° C. with a flat plate press to obtain a porous ion exchanger sheet-like material having a thickness of 0.6 cm. The porosity of the continuous voids of this porous sheet was 23% by volume. The porous ion exchange sheet was accommodated in a desalting chamber of an electrodialysis tank having the same configuration as that of Example 1 except that the thickness of the desalting chamber was 0.8 cm, and the volume filling rate was 54%. When the specific resistance in 10 μS / cm water was measured after water and 24 hours pre-energization treatment, the current density was 0.0025 A / cm. ² At that time, it was 1164 Ω · cm.
[0034]
After measuring the specific resistance, deionized water was produced. As the electrodialysis tank, the same electrodialysis tank as in Example 1 was used except for the thickness of the desalination chamber. Water having an electric conductivity of 5 μS / cm is used as raw water, and the current density is 0.004 A / cm. ² When desalting was performed at (voltage = 5 V per unit cell), treated water with an electric conductivity of 0.060 μS / cm was 0.45 m. ^Three It was stably obtained at a production rate of / h. In this case, 1m of production water ^Three Effective area of membrane used per 1h is 1.13m ² Met. After the operation, the ion exchange sheet in the desalting chamber was taken out, and the volume in the free state was measured. As a result, it was 111% of the volume of the desalting chamber. Further, when the same dry ion exchanger sheet as in this example was passed through the metal container 10 of the measuring apparatus shown in FIG. 2 at the same volume filling rate and the generated pressure was measured, the pressure was 1.2 kg / cm. ² Met.
[0035]
Example 3
Sodium sulfonate type (Na type) cation exchange resin (trade name: 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 dry resin, and A quaternary ammonium salt type (Cl type) anion exchange resin (product name: Diaion SA-10A, manufactured by Mitsubishi Chemical Corporation) having a particle size of 400 to 600 μm and an ion exchange capacity of 3.5 meq / g dry resin. It was dried with hot air at a temperature of 50 ° C. to adjust the water content to 8% by weight. Each ion-exchange resin was mixed with 3% by weight of linear low-density polyethylene (manufactured by Dow Chemical Company, trade name: Affinity SM-1300) and kneaded at a temperature of 120 to 130 ° C. Each obtained kneaded material was thermoformed at a temperature of 130 ° C. with a flat plate press to obtain a porous cation exchanger sheet and a porous anion exchanger sheet having a thickness of 0.6 cm. The porosity of continuous voids of the obtained porous cation exchanger sheet was 24% by volume, and the porosity of the porous anion exchanger sheet was 23% by volume.
[0036]
Using these porous ion exchanger sheet-like materials, a combination of a cation exchanger domain (region) and an anion exchanger domain (region) having the shape shown in FIGS. In the same electrodialysis tank as in Example 2, the desalting chamber having a thickness of 0.8 cm was filled at a volume filling rate of 66%. 3 (a) is a plan view, FIG. 3 (b) is a cross-sectional view taken along line YY in FIG. 3 (a), and in FIG. 3, reference numeral 16 denotes an anion exchanger domain, and reference numeral 17 denotes a cation exchanger domain. Is shown. When the specific resistance in 10 μS / cm water was measured after 60 minutes of water flow and 24 hours of pre-energization, the current density was 0.0025 A / cm. ² At that time, it was 911 Ω · cm.
[0037]
After measuring the specific resistance, deionized water was produced. The same electrodialysis tank as used in Example 2 was used as the electrodialysis tank. Water having an electric conductivity of 5 μS / cm is used as raw water, and the current density is 0.004 A / cm. ² When desalting was performed at (voltage = 5 V per unit cell), the treated water having an electric conductivity of 0.057 μS / cm was 0.47 m. ^Three It was stably obtained at a production rate of / h. In this case, 1m of production water ^Three Effective area of membrane used per hour / h is 1.08m ² Met. After the measurement, the ion exchange resin in the desalting chamber was taken out and the volume was measured. As a result, the volume was 134% of the volume of the desalting chamber. Further, when the same dry ion exchanger as in the present example was put into the metal container 10 of the measuring apparatus shown in FIG. 2 with the same volume filling rate and the generated pressure was measured by passing water, the pressure was 4.2 kg / cm. ² Met.
[0038]
Example 4
Sodium sulfonate type (Na type) cation exchange resin (trade name: 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 dry resin, and A quaternary ammonium salt type (Cl type) anion exchange resin (product name: Diaion SA-10A, manufactured by Mitsubishi Chemical Corporation) having a particle size of 400 to 600 μm and an ion exchange capacity of 3.5 meq / g dry resin. It was dried with hot air at a temperature of 50 ° C. to adjust the water content to 8% by weight. Each ion exchange resin was mixed with 3% by weight of 1,2-polybutadiene (RB-820, manufactured by Nippon Synthetic Rubber Co., Ltd.) and kneaded at a temperature of 120 to 130 ° C. Each obtained kneaded material was thermoformed at a temperature of 130 ° C. with a flat plate press to obtain a porous cation exchanger sheet and a porous anion exchanger sheet having a thickness of 0.6 cm. The porosity of continuous voids of the obtained porous cation exchanger sheet was 24% by volume, and the porosity of the porous anion exchanger sheet was 23% by volume.
[0039]
A combination of the cation exchanger domain (region) and the anion exchanger domain (region) having the shape shown in FIGS. 4 (a) to 4 (b) using these both porous ion exchanger sheets. Was filled in a desalting chamber having a thickness of 0.8 cm at a volume filling rate of 55%. 4A is a plan view, and FIG. 4B is a cross-sectional view taken along the line ZZ in FIG. 4A. In FIG. 4, reference numeral 16 denotes an anion exchanger domain, and reference numeral 17 denotes a cation exchanger. Shows the domain. When the specific resistance in 10 μS / cm water was measured after 60 minutes of water flow and 24 hours of pre-energization, the current density was 0.0025 A / cm. ² In this case, the value was 1206 Ω · cm, and a value lower than 1362 Ω · cm when an undried regenerated ion exchange resin having the same mixing ratio was measured in a cell was obtained.
[0040]
After measuring the specific resistance, deionized water was produced. The same electrodialysis tank as that used in Example 2 was used. Water having an electric conductivity of 5 μS / cm is used as raw water, and the current density is 0.004 A / cm. ² When desalting was performed at (voltage = 5 V per unit cell), treated water having an electric conductivity of 0.057 μS / cm was 0.46 m. ^Three It was stably obtained at a production rate of / h. In this case, 1m of production water ^Three Effective area of membrane per 1h is 1.10m ² Met. After the measurement, the ion exchange resin in the desalting chamber was taken out and the volume was measured. As a result, it was 113% of the volume of the desalting chamber. Further, when the same dry ion exchanger as in this example was put into the metal container 10 of the measuring apparatus shown in FIG. 2 at the same volume filling rate and the generated pressure was measured by passing water, the pressure was 1.3 kg / cm. ² Met.
[0041]
《Comparative example》
A sulfonic acid type (H type) cation exchange resin (trade name: 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 dry resin, and A quaternary ammonium salt type (OH type) anion exchange resin (trade name: Diaion SA-10A, manufactured by Mitsubishi Chemical Corporation) having a particle size of 400 to 600 μm and an ion exchange capacity of 3.5 meq / g dry resin. After regenerating with hydrochloric acid and sodium hydroxide aqueous solution, the mixture was mixed with cation exchange resin / anion exchange resin = 40/60 (volume ratio in a wet state) to obtain a mixture having an ion exchange capacity ratio of 50/50.
[0042]
This wet regenerated ion exchange resin mixture is filled 100% by volume filling rate into the desalting chamber of the electrodialysis tank having the same configuration as in Example 1 except that the width of the desalting chamber is 0.8 cm, When the specific resistance in 10 μS / cm water was measured after 60 minutes of water flow and 24 hours of pre-energization, the current density was 0.0025 A / cm. ² At that time, it was 1362 Ω · cm. After measuring the specific resistance, deionized water was produced. The same electrodialysis tank as in Example 1 was used except that the thickness of the desalting chamber was different. Water having an electric conductivity of 5 μS / cm is used as raw water, and the current density is 0.005 A / cm. ² When desalting was performed at (voltage = 5 V per unit cell), the treated water with an electric conductivity of 0.07 μS / cm was 0.04 m. ^Three / H production only. When the amount of treated water was increased, the conductivity increased and the amount of treated water could not be increased. In this case, 1m of production water ^Three Effective area of membrane used per hour / h is 12.68m ² It was a big value.
[0043]
【The invention's effect】
According to the deionized water production apparatus of the present invention, the electrical resistance can be reduced by increasing the adhesion between the ion exchangers housed in the demineralization chamber of the electrodialysis tank (to each other) and the ion exchange membrane, The thickness of the desalination chamber can be increased. Therefore, an apparatus having a small membrane use area and a large production water volume can be obtained.
[Brief description of the drawings]
FIG. 1 is a diagram schematically illustrating an example of a self-regenerating electrodialysis apparatus.
FIG. 2 is a diagram showing an outline of an apparatus for measuring a pressure generated by passing water of a dry ion exchanger in the present example.
FIG. 3 is a view showing an example of a porous ion exchange resin body in which both Yin and Yang porous ion exchanger sheet-like materials are formed in an island shape (used in Example 3).
FIG. 4 is a diagram showing an example of a porous ion exchange resin body in which both Yin and Yang porous ion exchanger sheet-like materials are formed in a multilayer shape (used in Example 4).
[Explanation of symbols]
A anion exchange membrane
K cation exchange membrane
1 container (electrodialysis tank)
2 Anode chamber
3 Cathode chamber
4 Anode
5 Cathode
S ₁ , S ₂ ... Sn enrichment chamber
R ₁ , R ₂ ... Rn desalination chamber
D ₁ , D ₂ , D _Three ... Dn desalination chamber frame
C ₁ , C ₂ , C _Three ... Cn enrichment chamber frame
N ₁ , N ₂ , N _Three ... Nn spacer
6 Liquid to be treated inlet
7 Deionized water conduit
8 Concentrated liquid inlet tube
9 Condensate conduit
10 Metal container
11 Metal plate
12 Water inlet
13 Water outlet
14 Load cell
15 Dry ion exchanger
16 Anion exchanger domain
17 Cation exchanger domain

Claims (5)

Deionized water containing an ion exchanger 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 to form a desalting chamber and a concentrating chamber In the production apparatus, a pressure of 0.1 to 20 kg / cm ² is generated between the ion exchanger accommodated in the desalting chamber and the cation exchange membrane and the anion exchange membrane partitioning the desalting chamber. An apparatus for producing deionized water.   The deionized water production apparatus according to claim 1, wherein the demineralization chamber has a thickness of 0.7 to 30 cm.   The means for generating pressure between the ion exchanger accommodated in the desalting chamber and the cation exchange membrane and the anion exchange membrane accommodates the ion exchanger in the desalting chamber and mechanically increases the volume of the desalting chamber. The deionized water production apparatus according to any one of claims 1 to 2, wherein the deionized water production unit is means for increasing the pressure by reducing the pressure. The means for generating the pressure introduces a spacer that contracts by pressure between the chamber frame of the desalting chamber and the ion exchange membrane, and after filling the ion exchanger, compresses by applying pressure from the outside, thereby desalting. The deionized water production apparatus according to claim 3 , which is means for reducing the chamber volume by 5 to 60% by volume. The deionized water production apparatus according to any one of claims 1 to 4 , wherein a net-like spacer is inserted and disposed in the concentration chamber.

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