JP5940387B2 - Electric deionized water production apparatus and deionized water production method - Google Patents

Description

  The present invention relates to an electric deionized water production apparatus and a deionized water production method used in various fields such as semiconductor manufacturing field, pharmaceutical manufacturing field, power generation field such as nuclear power and thermal power, food industry, or research facilities. .

  As an apparatus for producing deionized water, an electric deionized water production apparatus (hereinafter abbreviated as EDI) is known. A general EDI configuration includes a desalting chamber, a pair of concentrating chambers disposed on both sides of the desalting chamber, an anode chamber disposed outside one concentrating chamber, and an outside of the other concentrating chamber. And a cathode chamber arranged. The desalting chamber has an anion exchange membrane and a cation exchange membrane arranged opposite to each other, and an ion exchanger (anion exchanger and / or cation exchanger) filled between the exchange membranes.

In order to produce deionized water (treated water) by EDI configured as described above, water to be treated is introduced into the demineralized chamber with a DC voltage applied between the electrodes provided in the anode chamber and the cathode chamber, respectively. Pass water. The ionic component in the water to be treated is adsorbed by the ion exchanger in the demineralization chamber and subjected to deionization (demineralization) treatment. Specifically, anion components (Cl ⁻ , CO ₃ ²⁻ , HCO ₃ ⁻ , SiO _2, etc.) are adsorbed by the anion exchanger in the desalting chamber, or cation components (Na ⁺ , Ca ² ) by the cation exchanger. ⁺ , Mg ^2+, etc.) are adsorbed. In the desalting chamber, a dissociation reaction of water occurs due to the applied voltage, and hydrogen ions and hydroxide ions are generated (H ₂ O → H ⁺ + OH ⁻ ). The anion component adsorbed on the anion exchanger is exchanged with the hydroxide ion and released from the anion exchanger, and the cation component adsorbed on the cation exchanger is exchanged with the hydrogen ion and released from the cation exchanger. The released anion component (or cation component) travels through the anion exchanger (or cation exchanger) to the anion exchange membrane (or cation exchange membrane), is electrodialyzed on the membrane, and is concentrated water flowing through the concentration chamber. To be discharged.

  As described above, in the electric deionized water production apparatus, hydrogen ions and hydroxide ions continuously act as a regenerant (acid or alkali) for regenerating the ion exchanger. For this reason, regeneration with a chemical | medical agent is fundamentally unnecessary, and there exists an advantage that a continuous driving | operation can be performed, without performing reproduction | regeneration of the ion exchanger by a chemical | medical agent.

  Further, in the EDI, the above-described desalting chamber is divided into two parts by an ion exchange membrane into a small desalting chamber on the anode side and a small desalting chamber on the cathode side (hereinafter abbreviated as EDI of a two-salt chamber type). Is proposed by the present applicant (see Patent Document 1). In this configuration, the water to be treated is caused to flow into one small desalination chamber, the effluent water from the small desalting chamber is caused to flow into the other small desalination chamber, and the concentrated water is allowed to flow into each concentration chamber. By removing the impurity ions, deionized water can be obtained. In the case of the EDI configuration of the two-salt chamber type EDI, the number of concentration chambers per desalting chamber filled with the ion exchanger can be reduced to about half that in the case of the above-mentioned EDI. There is an advantage that the electrical resistance can be significantly reduced.

  The ion exchange membrane that partitions between the two small desalting chambers is called an intermediate membrane in order to distinguish it from other ion exchange membranes. Depending on the quality of the water to be treated and the water quality required for deionized water, the intermediate membrane is a single membrane of anion exchange membrane or cation exchange membrane, or a bipolar membrane in which an anion exchange membrane and a cation exchange membrane are laminated and bonded together A film (hereinafter abbreviated as BP film) can be used (see Patent Document 2).

Japanese Patent No. 3385553 (JP) JP 2009-208946 A (JP)

  However, in the conventional EDI of the above-described conventional two-salt desalination chamber, from the downstream side of the first small desalination chamber (D1) through which the treated water is first passed, The component that has permeated and moved through the intermediate membrane to the second small desalting chamber (D2) through which the water to be treated is passed before reaching the ion exchange membrane adjacent to the concentrating chamber. In some cases, it was discharged from the outlet of the deionized water in the salt chamber (D2).

For example, FIG. 5 uses an anion exchange membrane 1 as an intermediate membrane 1 partitioned into two small desalting chambers D1 and D2, and a mixed bed configuration of an anion exchanger and a cation exchanger in the first small desalting chamber D1 ( The mixed ion exchanger 2) is filled, the anion exchanger 3 is filled in the second small desalting chamber D2, and the flow C of water to be treated in the small desalting chambers D1 and D2 is in the same direction (from the top of the drawing). The example below is shown. CEM is an abbreviation for a cation exchange membrane, and AEM is an anion exchange membrane. In FIG. 5, the anion components (Cl ⁻ , CO ₃ ²⁻ , HCO ₃ ⁻ , SiO ₂ ⁻ ) that have permeated through the intermediate membrane 1 (anion exchange membrane) from the outlet 4 of deionized water in the second small desalting chamber D2. Etc.) is indicated by an arrow P. In particular, since silica is often ionized in the process of passing through the desalting chamber, it is likely to leak out from the deionized water outlet 4 of the second small desalting chamber D2.

Furthermore, FIG. 6 uses a cation exchange membrane as the intermediate membrane 1 and fills the first small desalting chamber D1 with a mixed bed form of anion exchanger and cation exchanger (mixed ion exchanger 2). In this example, the cation exchanger 8 is filled in the small desalting chamber D2 and the flow C of the water to be treated in the small desalting chambers D1 and D2 is in the same direction (from the top to the bottom of the drawing). In FIG. 6, cation components (Na ⁺ , Ca ²⁺ , Mg ^2+, etc.) that have permeated through the intermediate membrane (cation exchange membrane) leak from the outlet 4 of deionized water in the second small desalting chamber D2. Is indicated by an arrow P.

  As described above, the ions being electrophoresed to the electrode side sometimes exit from the deionized water outlet at the most downstream side of the demineralization chamber without countering the flow of the water to be treated. For this reason, it was examined to increase the applied current between the anode and the cathode to deal with ion leakage. However, if the applied voltage is increased to increase the current flowing between the electrodes, the intermediate film and the ion exchanger deteriorate. There is an upper limit to the current value that can be increased, and ion leakage may not be sufficiently suppressed.

On the other hand, since the BP membrane is a membrane in which a cation exchange membrane and an anion exchange membrane are overlapped and joined, neither the cation component nor the anion component is allowed to permeate. For this reason, by using a BP film as the intermediate film, the above-described problem of ion leakage can be solved. For example, in the example of FIG. 5, as shown in FIG. 7, the BP membrane 5 is installed so that the anion exchange membrane is in contact with the small desalting chamber D1 side of the intermediate membrane 1 (anion exchange membrane). It is possible to prevent leakage of anion components such as SiO ₂ ⁻ from the deionized water outlet 4 of the small desalting chamber D2. In addition, since the BP membrane 5 has a very accelerated water dissociation reaction at the interface between the cation exchange membrane and the anion exchange membrane, the applied voltage between the electrodes can be kept low.

  However, as can be seen from FIG. 7, since the BP film 5 does not transmit ions, only the ion removal in one direction is performed in each of the small desalting chambers D1 and D2. For this reason, the EDI of the desalination chamber two-chamber type using a BP membrane as the intermediate membrane is more than the case where a single membrane such as an anion exchange membrane or a cation exchange membrane is used for the EDI intermediate membrane of the desalination chamber two-chamber type. However, another problem arises that the water quality obtained is inferior.

  Therefore, in view of the above-mentioned problems, the present invention provides a technology that can improve the quality of treated water by exhibiting high deionization performance while keeping the applied voltage between the electrodes low with respect to the conventional EDI of the two-salt chamber. The purpose is to do.

The present invention relates to a desalting chamber, a pair of concentrating chambers provided on both sides of the desalting chamber, and an anode provided on the side opposite to the desalting chamber side with respect to one of the pair of concentrating chambers And an electric deionized water production apparatus comprising a cathode provided on the opposite side of the demineralization chamber with respect to the other of the pair of concentration chambers, wherein the demineralization chamber is formed by an ion exchange membrane. , is bounded Subdivision into two chambers of the first and second small depletion chamber arranged in the flowing direction in the anode and the cathode, the first and second small depletion chamber, the treatment water is first small is communicated with so that to pass through the second small depletion chamber after passing through the depletion chamber, the ion exchange membrane, the desalting compartment of the first cathode side small depletion chamber and the anode-side second An anion exchange membrane that partitions the small desalting chamber, or a cation exchange membrane that partitions the desalting chamber into a first small desalting chamber on the anode side and a second small desalting chamber on the cathode side there, engaged in equipment .

The in order to solve the above problems, an aspect of the present invention, further comprising a bipolar membrane formed by bonding an anion exchange membrane and a cation exchange membrane, which defines a said first and second small depletion chamber The bipolar membrane is placed on the ion exchange membrane. A plurality of holes are provided in a region of the bipolar membrane excluding the vicinity of the most downstream outlet of the desalting chamber. Another aspect of the present invention is a method for improving the quality of treated water by adopting the configuration according to the above-described aspect.

Taking such forms, in the process of the water to be treated passes through the first small depletion chamber, the ion component of the water to be treated, said first BP membrane in water flow upstream side of the small depletion chamber a plurality of holes, and through the intermediate layer is penetrating into the second small depletion chamber, said in the first water passage downstream side of the small depletion chamber by the region a plurality of holes is not a BP layer , ion penetration of the to the second sub-desalination chamber is prevented. Consequently, the desalination chamber of deionized water outlet of the most downstream of the second small depletion chamber where an exit, not easily ion component which has passed through the intermediate film leaks, after passing desalting compartment The water quality of deionized water can be improved over the prior art. At the same time, the water dissociation reaction is greatly accelerated in the BP film adjacent to the intermediate film, so that the operating voltage can be kept low.

  ADVANTAGE OF THE INVENTION According to this invention, with respect to the conventional demineralization room | chamber two-chamber type EDI, a high deionization performance can be exhibited, suppressing the applied voltage between electrodes low, and a treated water quality can be improved.

Sectional drawing which shows the structure of the desalination room | chamber chamber type EDI demineralization chamber by 1st embodiment of this invention. The top view of BP film | membrane used for 1st embodiment. Sectional drawing which shows the structure of the desalination chamber of EDI of the 2 type desalination chamber type EDI by 2nd embodiment of this invention. Sectional drawing which shows the structural example of the desalination chamber 2 chamber type EDI to which this invention is applied. Sectional drawing which shows the structure of the desalination chamber of the desalination chamber 2 chamber type EDI regarding a prior art. Sectional drawing which shows the structure of the desalination chamber of the desalination chamber 2 chamber type EDI regarding a prior art. Sectional drawing which shows the structure of the desalination chamber of the desalination chamber 2 chamber type EDI regarding a prior art.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Here, the same reference numerals are used for the same components as those in the conventional structure described with reference to FIGS. 5 to 7, and descriptions thereof are mainly described.

[First embodiment]
FIG. 1 is a cross-sectional view showing a configuration of an EDI desalination chamber of a two-salt chamber type EDI according to the first embodiment of the present invention. In the EDI of the desalination chamber two-chamber type, the desalination chamber is divided into two chambers (first small desalination chamber D1 and second small desalination chamber D2) arranged in the direction of applied current. This is an example in which an anion exchange membrane is provided on the intermediate membrane 1 (ion exchange membrane) that partitions the chamber. In the figure, the anion exchange membrane is abbreviated as AEM, and the cation exchange membrane is abbreviated as CEM. A BP membrane is placed so as to be in contact with the anion exchange membrane surface of the BP membrane 5 on the cathode side surface of the intermediate membrane 1 (AEM). On the other hand, the cation exchange membrane surface of the BP membrane 5 is in contact with the mixed ion exchanger (mixed bed form of anion exchanger and cation exchanger) 2 filled in the first small desalting chamber D1. The first small desalting chamber D1 may be filled with a simple substance of cation exchange resin. The second small desalting chamber D2 may be filled with the anion exchanger 3.

  Further, a plurality of holes 6 are provided in a predetermined region of the BP film 5. These holes 6 are not formed in the anion exchange membrane which is the intermediate membrane 1. FIG. 2 shows a plan view of the BP film 5 of the present embodiment. A region 7 in the BP membrane 5 where the plurality of holes 6 are not provided is located in the vicinity of the outlet 4 on the most downstream side of the desalting chamber. That is, the region 7 having no plurality of holes 6 in the BP film 5 is a predetermined range from one end of the BP film 5 on the outlet 4 side of the second small desalting chamber D2 to the side opposite to the one end. Are provided.

In such a form, in the process in which the water to be treated flowing from the inlet of the first small desalting chamber D1 passes through the mixed ion exchanger 2, the cation component in the water to be treated is electrophoresed to the negative electrode side and becomes a cation. It passes through the exchange membrane and is discharged into a concentration chamber (not shown). On the other hand, the anion component in the for-treatment water in the first small desalting chamber D1 is electrophoresed to the anode side. At this time, the anion component passes through the plurality of holes 6 of the BP membrane 5 and further the intermediate membrane 1 of the anion exchange membrane on the upstream side in the water flow direction of the first small desalination chamber D1. Intrusion into the salt chamber D2 is performed in the second small desalination chamber D2 by the region 7 without the plurality of holes 6 in the BP membrane 6 on the downstream side in the water flow direction of the first small desalination chamber D1. Be blocked. As a result, the anion components (Cl ⁻ , CO ₃ ²⁻ , HCO ₃ ⁻ , SiO ₂ ^−, etc.) that have passed through the intermediate membrane 1 of the anion exchange membrane leak from the outlet 4 of the second small desalting chamber D2. The quality of the water to be treated can be improved as compared with the prior art.

  In particular, since silica contained in the water to be treated is not ionized in a normal state and is ionized in the process of passing through the first small desalting chamber D1, it is downstream of the first small desalting chamber D1 in the water flow direction. However, according to this embodiment, silica ions near the outlet of the first small desalination chamber D1 cannot enter the second small desalination chamber D2 due to the presence of the BP membrane 5, Silica leakage from the outlet 4 of the second small desalting chamber D2 can be prevented.

[Second Embodiment]
FIG. 3 is a cross-sectional view showing a configuration of a D2EDI desalting chamber according to a second embodiment of the present invention. This form is an example in which a cation exchange membrane is provided in the intermediate membrane 1 (ion exchange membrane) that partitions two chambers (first small desalination chamber D1 and second small desalination chamber D2) arranged in the voltage application direction. . In the figure, the anion exchange membrane is abbreviated as AEM, and the cation exchange membrane is abbreviated as CEM. The BP membrane 5 is placed so as to be in contact with the cation exchange membrane surface of the BP membrane 5 on the anode side surface of the intermediate membrane 1 (CEM). On the other hand, the anion exchange membrane surface of the BP membrane 5 is in contact with the mixed ion exchanger 2 filled in the first small desalting chamber D1. A cation exchanger 8 is filled in the second small desalting chamber D1 of the present embodiment. The first small desalting chamber D1 may be filled with the anion exchanger 3.

  Further, a plurality of holes 6 are provided in a predetermined region of the BP film 5. Those holes 6 are not formed in the cation exchange membrane which is the intermediate membrane 1. A region 7 in the BP membrane 5 where the plurality of holes 6 are not provided is located in the vicinity of the outlet 4 on the most downstream side of the desalting chamber. That is, the region without the plurality of holes 6 in the BP film 5 is within a predetermined range from one end of the BP film 5 on the outlet 4 side of the second small desalination chamber D2 to the side opposite to the one end. It is provided over. The arrangement of the plurality of holes 6 is the same as in FIG.

In such a form, in the process in which the water to be treated flowing from the inlet of the first small desalting chamber D1 passes through the mixed ion exchanger 2, the anion component in the water to be treated is electrophoresed to the anode side and becomes an anion. It passes through the exchange membrane and is discharged into a concentration chamber (not shown). On the other hand, the cation component in the for-treatment water in the first small desalting chamber D1 is electrophoresed on the negative electrode side. At this time, the cation component passes through the plurality of holes 6 of the BP membrane 5 and further the intermediate membrane 1 of the cation exchange membrane on the upstream side of the first small desalination chamber D1 in the water flow direction. Intrusion into the salt chamber D2 is caused by the region 7 without the plurality of holes 6 of the BP membrane 5 on the downstream side of the first small desalination chamber D1 in the water flow direction, so that ion intrusion into the second small desalination chamber D2 occurs. Be blocked. As a result, the cation components (Na ⁺ , Ca ²⁺ , Mg ^2+, etc.) that have passed through the intermediate membrane 1 of the cation exchange membrane do not leak out from the outlet 4 of the second small desalting chamber D2, and the object to be processed The water quality can be improved over the prior art.

[Other Embodiments]
In the above description, the first embodiment in which an anion exchange membrane is used for the EDI intermediate membrane 1 of the desalination chamber two-chamber type and the second embodiment in which a cation exchange membrane is used for the intermediate membrane 1 have been described. In the intermediate film 1 of these embodiments, a part of the BP film 5 having a plurality of holes 6 is overlapped, and the region without the holes 6 in the BP film 5 is the second small desalination chamber. It is provided over a predetermined range from one end of the BP film 5 on the outlet 4 side of D2 to the side opposite to the one end.

  Ion leakage from the outlet 4 of the second small desalination chamber D2 can be prevented as the range of the region without the hole 6 becomes larger. The area | region which can be permeate | transmitted to the desalting chamber D2 decreases, and the efficiency of the deionization process with respect to to-be-processed water falls. For this reason, it is necessary to determine the range of the region 7 without the hole 6 in the BP membrane 5 according to the water quality required for the water to be treated, and the BP membrane on the outlet 4 side of the second small desalination chamber D2. It is desirable to extend from the end of 5 to half of the BP film 5 at the maximum.

  Further, in each of the above-described embodiments, the example in which the flow C of the water to be treated in each of the small desalting chambers D1 and D2 is set in the same direction (from the top to the bottom of the drawing) is shown. Applicable even if the water to be treated is not flowing. For example, the flow directions of the water to be treated may be opposite to each other in the first small desalting chamber D1 and the second small desalting chamber D2. In this case, the to-be-treated water inlet and the deionized water outlet of the second small desalting chamber D2 are at positions opposite to those in the above-described embodiments. Along with this, it is necessary to reverse the region where the hole 6 exists in the BP film 5 and the region where the hole 6 does not exist. For example, in the form of FIG. 1, the treated water inlet of the second small desalting chamber D2 is located on the lower side of the drawing, and the deionized water outlet of the second small desalting chamber D2 is located on the upper side of the drawing, In connection with this, the area | region with the hole 6 in the BP film | membrane 5 becomes a drawing lower side, and the area | region without the hole 6 becomes a drawing upper side.

  Eventually, even when the flow of the water to be treated to the small desalting chambers D1 and D2 is changed from the same direction to the opposite directions, the plurality of holes 6 provided in the BP film 5 are provided in the second small desalting chamber D2. If it is not provided within a predetermined range from the end of the BP film 5 on the outlet 4 side, ion leakage, which is a problem of the present application, can be solved.

  In each embodiment, the plurality of holes 6 opened in a part of the BP film 5 disposed adjacent to the intermediate film 1 are equally arranged in a part (region) thereof. If one large hole is formed in a part of the BP film 5, the current flows to a portion having a relatively small electric resistance, so that the current density between the anode and the cathode is in the portion where the bipolar film is installed. It tends to be biased and uneven. This non-uniform current density reduces the efficiency of electrophoresis and electrodialysis for ions in the water to be treated in the desalting chamber. In contrast, in the configuration of the present application in which a plurality of holes 6 are evenly arranged in a part of the BP film 5, the applied current between the anode and the cathode flows almost uniformly to the desalting chamber. Electrophoresis and electrodialysis between the cathodes can be performed stably.

  Further, in each of the above-described embodiments, the desalination treatment unit configured by the desalination chamber partitioned into two chambers by the intermediate membrane 1 and the pair of concentration chambers arranged on both sides of the desalination chamber is used as a cathode and an anode. However, an EDI having two or more desalting units is also included in the present invention.

  Next, the effects of the present invention will be described in comparison with Example 1 and some comparative examples.

  As shown in FIG. 4, the EDI of the desalination chamber two-chamber type according to the present embodiment includes a desalination chamber D, a pair of concentration chambers C1, C2 arranged on both sides of the desalination chamber D, The anode chamber E1 disposed outside the concentrating chamber C1 and the cathode chamber E2 disposed outside the other concentrating chamber C2, and the desalting chamber D is formed by the intermediate membrane (ion exchange membrane) 1 It is divided into two small desalting chambers D1, D2 arranged in the energization direction between the anode and the cathode. In FIG. 4, the anion exchange membrane is abbreviated as AEM, and the cation exchange membrane is abbreviated as CEM.

  Here, an EDI having a desalination chamber two-chamber type equipped with a desalination chamber having the structure shown in FIG.

  Example 1 is an example in which the intermediate membrane in the desalting chamber is an anion exchange membrane, and a BP membrane having a large number of pores in part is placed on the intermediate membrane.

  Furthermore, Comparative Example 1, Comparative Example 2, and Comparative Example 3 to be compared with Example 1 were prepared.

  Comparative Example 1 is an example (not shown) in which a large number of holes are provided over the entire surface of the BP film with respect to Example 1.

  Comparative Example 2 is an EDI having a desalination chamber two-chamber type including the desalination chamber having the structure shown in FIG. 5, that is, an example in which no BP membrane is provided for Example 1.

  Comparative Example 3 is an EDI having a desalination chamber two-chamber type having a desalination chamber having the structure shown in FIG. 7, that is, an example in which no hole is provided in the BP membrane with respect to Example 1.

  The flow of water to be treated to these desalting chambers is the same, and the first small desalting chamber D1 and the second small desalting chamber are shown in FIG. 1, FIG. 5, FIG. The flow direction of the water to be treated was the same as D2.

  Using such Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3, the effect of the present invention was confirmed.

The specifications of the EDI of the desalination chamber two-chamber type in Example 1 and Comparative Examples 1 to 3, the water flow rate, the specifications of the supply water, etc. are as follows. In addition, CER is an abbreviation for a cation exchanger (cation exchange resin), AER is an anion exchanger (anion exchange resin), and MB is a mixed ion exchanger (mixed bed form of a cation exchanger and an anion exchanger).
・ Anode chamber: dimension 200 × 250 × 5 mm CER filling ・ cathode chamber: dimension 200 × 250 × 5 mm AER filling ・ first small desalination chamber D1: dimension 200 × 250 × 10 mm MB filling (mixing ratio 1: 1)
・ Second small desalination chamber D2: dimension 200 × 250 × 10 mm AER filling ・ Each concentration chamber: 200 × 250 × 5 mm AER filling ・ Flow rate of treated water in small desalination chambers D1 and D2: 50 L / h
・ Flow rate of concentrated water in the concentration chamber: 20 L / h
-Flow rate of electrode water in the anode chamber and the cathode chamber: 10 L / h
・ Supply water to small desalination chamber (treated water): One-stage RO permeated water 9 to 10 μS / cm
・ Supply water to the concentrating chamber (concentrated water): single stage RO permeated water 9 to 10 μS / cm
・ Supply water to electrode chamber (electrode water): Desalination chamber treated water ・ Silica concentration in feed water (treated water) to small desalination chamber: 1 mg / L
-Applied current value: 2.0A
Under the above conditions, each of the EDIs in the demineralization chamber two-chamber type of Example 1 and Comparative Examples 1 to 3 is continuously operated for 200 hours, and the subsequent operation voltage, treated water quality (after passing the demineralization chamber) The specific resistance of the water to be treated) and the silica concentration in the water to be treated after passing through the desalting chamber were compared. The results are shown in Table 1.

  As shown in Table 1, Example 1, Comparative Example 1, and Comparative Example 3 in which a BP film was bonded to an intermediate film of a desalination chamber partitioned into two chambers were compared with Comparative Example 2 that did not have the BP film. The operating voltage was kept low. In Example 1, Comparative Example 1, and Comparative Example 2, the specific resistance value of the water to be treated after passing through the desalting chamber was as high as about 18 MΩ · cm, and extremely high water quality was obtained as compared with Comparative Example 3. In addition, the silica concentration in the water to be treated after passing through the desalting chamber showed a very low value of less than 10 μg / L in Comparative Example 3, whereas it was as high as 30 μg / L or more in Comparative Example 1 and Comparative Example 2. showed that.

  For these reasons, as in Example 1, a BP membrane was bonded to the intermediate membrane of the desalting chamber, and the predetermined range was removed from the end of the BP membrane on the outlet side of the second small desalting chamber D2. It was confirmed that by forming a plurality of holes in the portion, the treated water quality was improved while suppressing the operating voltage, and ion leakage (silica ion leakage in this example) could be reduced.

  In the above confirmation of the effect of the present invention, an example in which an anion exchange membrane is used as an intermediate membrane in a desalination chamber of a two-salt chamber type EDI is taken as an example. It is considered that the same effect as described above can be obtained even in the case of using (the structure of FIG. 3).

1: Intermediate membrane 2: Mixed ion exchanger 3: Anion exchanger 4: The most downstream outlet of the desalting chamber (deionized water outlet of the second small desalting chamber D2)
5: BP membrane 6: pore 7: region without a plurality of pores in the BP membrane 8: cation exchanger D: desalination chamber D1: first small desalination chamber D2: second small desalination chamber C1, C2: Concentration chamber E1: Anode chamber E2: Cathode chamber AEM: Anion exchange membrane CEM: Cation exchange membrane

Claims (10)

A desalting chamber; a pair of concentrating chambers provided on both sides of the desalting chamber; an anode provided on the opposite side of the desalting chamber with respect to one of the pair of concentrating chambers; A cathode provided on the side opposite to the desalting chamber side with respect to the other of the concentration chambers, and the desalting chamber is arranged in an energization direction between the anode and the cathode by an ion exchange membrane The first and second small desalting chambers are divided into two chambers, and the first and second small desalting chambers are configured such that the second treated water passes through the first small desalting chamber after the second treated water passes through the first small desalting chamber. of the communication in so that to pass through the small depletion chamber, the ion exchange membrane, the desalting compartment the second small depletion chamber of the anode side and the first small depletion chamber of the cathode-side Or an anion exchange membrane that is partitioned into two parts, or a partition that divides the desalting chamber into the first small desalting chamber on the anode side and the second small desalting chamber on the cathode side. Is exchange membrane, in electrodeionization water producing apparatus,
It further comprises a bipolar membrane formed by laminating an anion exchange membrane and a cation exchange membrane,
The bipolar membrane is placed over the ion exchange membrane, and a plurality of holes are provided in a region of the bipolar membrane excluding the vicinity of the most downstream outlet of the desalting chamber. Ionized water production equipment. The electric deionized water production apparatus according to claim 1 ,
Before Symbol ion-exchange membrane is that the anion-exchange membrane,
The bipolar membrane is placed so that the anion exchange membrane of the bipolar membrane is in contact with the surface on the cathode side of the anion exchange membrane,
An electric deionized water producing apparatus, wherein the second small desalting chamber is filled with at least an anion exchanger, and the first small desalting chamber is filled with at least a cation exchanger. The electric deionized water production apparatus according to claim 1 ,
Before Symbol ion-exchange membrane is said cation exchange membrane,
The bipolar membrane is placed so that the cation exchange membrane of the bipolar membrane is in contact with the anode side surface of the cation exchange membrane,
An electric deionized water production apparatus, wherein the first small desalting chamber is filled with at least an anion exchanger, and the second small desalting chamber is filled with at least a cation exchanger. The electric deionized water production apparatus according to any one of claims 1 to 3,
The region where the plurality of holes are not provided in the bipolar membrane is within a predetermined range from one end of the bipolar membrane on the outlet side of the second small desalination chamber to the side opposite to the one end. An electric deionized water production apparatus characterized by being provided over the entire area. The electric deionized water production apparatus according to any one of claims 1 to 4,
The electric deionized water production apparatus is characterized in that the flow direction of the water to be treated is the same in the first small desalting chamber and the second small desalting chamber. The electric deionized water production apparatus according to any one of claims 1 to 4,
The electric deionized water production apparatus characterized in that the flow directions of the water to be treated in the first small desalting chamber and the second small desalting chamber are opposite to each other.   3. The electric deionized water production apparatus according to claim 2, wherein the water to be treated flowing into the demineralization chamber contains silica.   7. The electric deionized water production apparatus according to claim 1, wherein the water to be treated flowing into the demineralization chamber is one-stage RO membrane permeated water. A desalting chamber; a pair of concentrating chambers provided on both sides of the desalting chamber; an anode provided on the opposite side of the desalting chamber with respect to one of the pair of concentrating chambers; A cathode provided on the side opposite to the desalting chamber side with respect to the other of the concentration chambers, and the desalting chamber is arranged in an energization direction between the anode and the cathode by an ion exchange membrane The ion exchange membrane is divided into two chambers, a first and a second small desalting chamber, and the ion exchange membrane separates the desalting chamber from the first small desalting chamber on the cathode side and the second small salt on the anode side. An anion exchange membrane that is partitioned into a desalting chamber, or the desalting chamber is partitioned into the first small desalting chamber on the anode side and the second small desalting chamber on the cathode side a cation exchange membrane, prepared electrodeionization water producing apparatus, passing the second small depletion chamber through by passing water to be treated to the first small depletion chamber In deionized water producing method for producing deionized water by,
A bipolar membrane formed by laminating an anion exchange membrane and a cation exchange membrane is placed on the ion exchange membrane, and a plurality of holes are provided in a region of the bipolar membrane excluding the vicinity of the most downstream outlet of the desalting chamber. A method for producing deionized water, characterized by comprising: A method for producing deionized water according to claim 9,
A region where the plurality of holes are not provided in the bipolar membrane is within a predetermined range from one end portion of the bipolar membrane on the outlet side of the second small desalting chamber to the side opposite to the one end portion. A method for producing deionized water, characterized in that the deionized water is provided.

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