KR102269869B1 - The deionized water manufacturing system, and the electric deionized water manufacturing device and deionized water manufacturing method - Google Patents

Abstract

A deionized water production system for producing deionized water by supplying raw water includes a reverse osmosis membrane device (RO device) to which raw water is supplied, and a desalination chamber partitioned by an ion exchange membrane to supply permeate water of the reverse osmosis membrane device. It includes an ionized water production device (EDI device). In the EDI apparatus, an ion exchanger is filled in the desalting chamber, and particles containing a polyvalent metal are adsorbed on at least one surface of at least a part of the ion exchange membrane and at least a part of the ion exchanger.

Description

The deionized water manufacturing system, and the electric deionized water manufacturing device and deionized water manufacturing method

The present invention relates to the production of deionized water, and more particularly, to a deionized water production system, an electric deionized water production apparatus, and a deionized water production method.

A deionized water production system is known in which water to be treated is passed through an ion exchanger such as an ion exchange resin and deionized by an ion exchange reaction. Such systems generally include a device having an ion exchanger to generate deionized water using an ion exchange reaction with the ion exchanger. However, in an apparatus having an ion exchanger, when the ion exchanger of the ion exchanger is saturated and the desalting performance is reduced, it is not necessary to perform a treatment for regenerating the ion exchanger with a chemical such as acid or alkali, that is, a regeneration treatment. have. In the regeneration treatment, cations (cations) and anions (anions) adsorbed to the ion exchanger are replaced with hydrogen ions (H ⁺ ) and hydroxide ions (OH ⁻ ) derived from acids or alkalis, whereby ions This is a treatment to revive the desalination performance of the exchanger. Therefore, the deionized water manufacturing apparatus using the ion exchanger has the problem that continuous operation cannot be performed and the labor of replenishing the chemical for the regeneration process is also required. In order to solve this problem, in recent years, an electric deionized water manufacturing apparatus (also called an EDI (ElectroDeIonization) apparatus) that does not require regeneration by a chemical has been developed and put into practical use.

EDI device is a device that combines electrophoresis and electrodialysis, and consists of a desalting chamber by filling an ion exchanger between an anion exchange membrane that transmits only anions and a cation exchange membrane that transmits only cations, and an anion exchange membrane and cations when viewed from the desalting chamber It has a structure in which each of the enrichment chambers is arranged outside the exchange membrane, and an anode chamber having an anode and a cathode chamber having a cathode are arranged outside them. The ion exchanger charged in the desalting chamber is at least one of an anion exchanger and a cation exchanger. In the desalting chamber, an anion exchange membrane is disposed on a side facing the anode, and a cation exchange membrane is disposed on a side facing the cathode. The concentration chamber may be filled with an ion exchanger, the anode chamber may be filled with a cation exchanger, and the cathode chamber may be filled with an anion exchanger.

In order to produce deionized water from untreated water by the EDI device, the deionized water is passed through the demineralization chamber while a DC voltage is applied between the anode and the cathode. Then, the ion component in the to-be-treated water is adsorbed to the ion exchanger in the desalination chamber, and deionization treatment, that is, desalination treatment is performed. As a result, deionized water flows out from the demineralization chamber. At this time, in the desalting chamber, the interface between the heterogeneous ion exchange materials, that is, the interface between the anion exchanger and the cation exchanger, the anion exchanger and the cation exchange membrane, the anion exchange membrane and the cation exchanger interface, and the anion exchange membrane and the cation exchange membrane At the interface of , a dissociation reaction of water occurs as shown in the following formula by the applied voltage to generate hydrogen ions and hydroxide ions.

H ₂ O → H ⁺ + OH ^-

By the hydrogen ions and hydroxide ions generated by this dissociation reaction, the ion components adsorbed to the ion exchanger in the desalting chamber are ion exchanged and released from the ion exchanger. Among the advantageous ion components, anions are electrophoresed to the anion exchange membrane, electrodialyzed by the anion exchange membrane, and discharged into concentrated water flowing through the concentration chamber on the side closer to the anode as viewed from the desalting chamber. Similarly, cations among the liberated ion components are electrophoresed to the cation exchange membrane, electrodialyzed by the cation exchange membrane, and discharged into the concentrated water flowing through the concentration chamber near the cathode as viewed from the desalination chamber. As a result, ion components in the water to be treated supplied to the desalination chamber are transferred to the concentration chamber and discharged, and at the same time, the ion exchanger in the desalination chamber is also regenerated.

In this way, in the EDI device, hydrogen ions and hydroxide ions generated by the application of a DC voltage continuously act as regenerating agents for acids and alkalis that regenerate ion exchangers. For this reason, in the EDI apparatus, it is basically unnecessary to perform the regeneration process with the chemical supplied from the outside, and continuous operation can be performed without regeneration of the ion exchanger by the chemical.

In the above, it is assumed that the basic configuration of [concentration chamber (C)|anion exchange membrane (AEM)|demineralization chamber (D)|cation exchange membrane (CEM)|concentration chamber (C)] is disposed between the anode and the cathode. This basic configuration is called a cell set. In practice, it is common to juxtapose a plurality of such cell sets between electrodes, and electrically connect the plurality of cell sets in series with one end as an anode and the other end as a cathode to increase processing capacity. In this case, since adjacent enrichment chambers can be shared between adjacent cell sets, the configuration of the EDI device is [anode chamber|C|AEM|D|CEM|C|AEM|D|CEM|C|AEM|D| CEM|… |C|cathode chamber]. In addition, in many cases, a cation exchange membrane is provided between the anode chamber and the concentrating chamber adjacent thereto, and an anion exchange membrane is provided between the cathode chamber and the concentrating chamber adjacent thereto. In addition, in such a series structure, for the desalination chamber closest to the anode chamber, the anode chamber itself can also function as a enrichment chamber without interposing an independent enrichment chamber between the anode chamber and the anode chamber. Similarly, for the demineralization chamber closest to the cathode chamber, the cathode chamber itself can also function as the enrichment chamber without interposing the enrichment chamber between the chamber and the cathode chamber. In order to suppress the electric power consumed by the application of a DC voltage, it is preferable to lower the electrical resistance by charging the ion exchanger in each of the enrichment chamber, the anode chamber, and the cathode chamber.

In order to obtain deionized water having a remarkably low impurity concentration in a deionized water production system having an EDI apparatus, it is preferable to use water in which impurities have been reduced to a certain extent in advance as the water to be treated to be supplied to the EDI apparatus. For this reason, for example, a reverse osmosis (RO) membrane device is installed at the front end of the EDI device to constitute a deionized water production system, and water that has passed through the reverse osmosis membrane device is supplied to the EDI device as target water. However, when the electrical conductivity of the water to be treated becomes small and, for example, 5 µS/cm or less, a dissociation reaction of water occurs, so the voltage that must be applied to the EDI device increases. In order to obtain deionized water with a lower impurity concentration, if water to be treated with a lower conductivity is used, if the current flowing between the anode and the cathode is constant, the voltage that must be applied to the EDI device, that is, the operating voltage, becomes higher. . As the operating voltage increases, the power consumption also increases accordingly.

As mentioned above, it is the dissociation reaction of water in the desalination chamber that plays an important role in the continuous production of deionized water by EDI apparatus. If the dissociation reaction of water is efficiently carried out, even when the conductivity of the water to be treated is low, the voltage applied to the EDI device can be kept low, so that it is possible to produce high-purity deionized water with low power consumption.

In order to promote the dissociation reaction of water in the desalting chamber of the EDI apparatus, several techniques have been proposed. Patent Document 1 discloses that, in an EDI apparatus, a metal hydroxide such as magnesium hydroxide is supported on the membrane surface of the cation exchange membrane on the side of the desalting chamber or on the ion exchange resin filled in the desalting chamber. Patent Document 2 discloses that, in an EDI apparatus, a metal oxide or metal hydroxide acting as an amphoteric ion exchanger is mixed in an ion exchanger in a desalting chamber at a ratio of 1 to 50% by volume.

[Prior art literature]

[Patent Literature]

(Patent Document 1) JP2000-350991 A

(Patent Document 2) JP2001-340865 A

However, in the apparatus described in Patent Document 1, since the metal hydroxide supported in the desalination chamber is dissolved by hydrogen ions generated by dissociation of water, it is difficult to stably maintain the performance over a long period of time. In the apparatus described in Patent Document 2, since the metal oxides and metal hydroxides mixed in the ion exchanger do not reliably exist at the interface between the different types of ion exchangers, the effect of promoting water dissociation cannot be exhibited to the maximum extent.

It is an object of the present invention to promote the dissociation reaction of water more stably and efficiently even when the water to be treated with low conductivity is supplied to an electric deionized water production apparatus in view of the problems of the conventional deionized water production system as described above. An object of the present invention is to provide a deionized water production system capable of producing high-purity deionized water with low power consumption, a method for producing deionized water, and an electric deionized water production apparatus that can be suitably used in the deionized water production system.

Another object of the present invention is to provide at least one of an ion exchange membrane and an ion exchanger used in an electric deionized water production apparatus.

According to one aspect of the present invention, a deionized water production system for producing deionized water by supplying raw water includes a reverse osmosis membrane device to which raw water is supplied, and a desalination chamber partitioned by an ion exchange membrane to supply permeate water of the reverse osmosis membrane device. An ion exchanger is filled in the demineralization chamber, and particles containing a polyvalent metal are adsorbed on at least one surface of at least a part of the ion exchange membrane and at least a part of the ion exchanger.

According to another aspect of the present invention, an electric deionized water production apparatus (EDI apparatus) includes at least one desalting chamber between an anode chamber having an anode and a cathode chamber having a cathode, the desalination chamber being located on a side facing the anode An EDI device comprising at least one of an anion exchanger and a cation exchanger in a desalting chamber, partitioned by an anion exchange membrane and a cation exchange membrane positioned toward the cathode, an anion exchange membrane, a cation exchange membrane, an anion exchanger and a cation exchange It is characterized in that particles containing a polyvalent metal are adsorbed on at least one surface of a sieve.

A polyvalent metal, ie, a metal element having an ionic value of 2 or more when it becomes a cation, acts as a catalyst for the dissociation reaction of water. In the present invention, by adsorbing particles containing a polyvalent metal to the surface of at least one of an anion exchanger, a cation exchanger, an anion exchange membrane, and a cation exchange membrane in the desalting chamber, a heterogeneous ion-exchangeable substance in the desalting chamber It becomes possible to reliably present a polyvalent metal acting as a catalyst for a water dissociation reaction at the interface between the two groups. For this reason, in the present invention, the effect of accelerating the water dissociation reaction by the polyvalent metal can be maximally obtained. In addition, since the particles containing the polyvalent metal have a particle shape, there is no risk of covering their surfaces when adsorbed to the ion exchanger or ion exchange membrane in the desalination chamber, so that the reactivity of ion exchange with respect to deionization is reduced. Loss of permeability of ions can be minimized.

According to another aspect of the present invention, in the method for producing deionized water, in the method for producing deionized water using the EDI device of the present invention, the current density in the demineralization chamber is 0.3A/dm ² or more and 10A/dm ^It is characterized in that the deionized water is obtained by flowing the water to be treated in the demineralization chamber while applying a DC voltage between the anode and the cathode so as to be 2 or less.

According to another aspect of the present invention, a method for producing deionized water includes at least one desalting chamber between an anode chamber having an anode and a cathode chamber having a cathode, wherein the desalting chamber includes an anion exchange membrane and a cathode positioned toward the anode. A method for producing deionized water using an EDI device partitioned by a cation exchange membrane located on the side facing toward and in which at least one of an anion exchanger and a cation exchanger is charged in a desalting chamber, an anion exchange membrane, a cation exchange membrane, and an anion exchanger and adsorbing particles containing a polyvalent metal on the surface of at least one of the cation exchangers. After the adsorption process, a DC voltage is applied between the anode and the cathode to flow the to-be-treated water into the desalination chamber to obtain deionized water. includes the process.

According to another aspect of the present invention, an ion exchange membrane for EDI device comprises at least one desalting chamber filled with at least one of an anion exchanger and a cation exchanger between an anode chamber having an anode and a cathode chamber having a cathode. An anion exchange membrane which is used in an EDI device provided with the desalting chamber and is located on a side facing the anode in the desalting chamber to partition the desalting chamber, a cation exchange membrane which is located on the side toward the cathode in the desalting room to partition the desalting chamber, and the inside of the desalting chamber In the ion exchange membrane which is at least one of the intermediate ion exchange membranes partitioning the demineralization chamber, it is characterized in that particles containing a polyvalent metal are adsorbed on the surface of the ion exchange membrane.

According to another aspect of the present invention, an ion exchanger for an EDI device comprises at least one desalting chamber between an anode chamber having an anode and a cathode chamber having a cathode, the desalting chamber being an anion exchange membrane positioned on a side facing the anode. An ion exchanger used in an EDI device partitioned by a cation exchange membrane positioned on the side facing the cathode and filled in a desalting chamber including at least one of an anion exchanger and a cation exchanger, the surface of the ion exchanger It is characterized in that particles containing a polyvalent metal are adsorbed to the

According to the present invention, particles containing a polyvalent metal are adsorbed to an ion exchanger or an ion exchange membrane in a desalting chamber of an EDI apparatus, so that particles containing a polyvalent metal are not used, as will be apparent from the examples to be described later. Compared to the EDI device, it is possible to promote the dissociation reaction of water more stably and efficiently, thereby making it possible to manufacture high-purity deionized water with low power consumption.

1 is a diagram showing the configuration of a deionized water production system according to the present invention.
2 is a view showing another example of the configuration of the deionized water production system.
3 is a view showing another example of the configuration of the deionized water production system.
4 is a schematic cross-sectional view showing a basic form of an electric deionized water production device (EDI device).
5A is a diagram for explaining the promotion of water dissociation by particles containing a polyvalent metal.
Fig. 5B is a diagram for explaining the promotion of water dissociation by particles containing a polyvalent metal.
6 is a schematic cross-sectional view showing another form of an EDI device according to the present invention.
7 is a schematic cross-sectional view showing another form of an EDI device according to the present invention.
8 is a schematic cross-sectional view showing another form of an EDI device according to the present invention.
9 is a schematic cross-sectional view showing another form of an EDI device according to the present invention.
10 is a schematic cross-sectional view showing another form of an EDI device according to the present invention.
11 is a view for explaining the promotion of water dissociation by particles containing a polyvalent metal.
12 is a schematic cross-sectional view showing another form of an EDI device according to the present invention.
13 is a schematic cross-sectional view showing another form of an EDI device according to the present invention.

Next, a preferred embodiment of the present invention will be described with reference to the drawings.

1 shows the configuration of a deionized water production system according to the present invention. Although this deionized water manufacturing system is equipped with the EDI apparatus 10, in order to obtain deionized water with sufficiently reduced impurity concentration, a reverse osmosis (RO) membrane apparatus installed in two stages in series at the front end of the EDI apparatus 10 (51, 52) is provided. The reverse osmosis membrane devices 51 and 52 respectively have reverse osmosis membranes 53 and 54 therein. Raw water is supplied to the reverse osmosis membrane device 51 in the first stage through a pump 55, and water that has passed through the reverse osmosis membrane 53 in the reverse osmosis membrane device 51, that is, permeate is the second stage. It is supplied to the reverse osmosis membrane device (52). The permeated water from the reverse osmosis membrane device 52 in the second stage is supplied to the EDI device 10 as target water. The configuration in which the two reverse osmosis membrane devices 51 and 52 are connected in series as a whole is a configuration in which two devices including the reverse osmosis membranes 53 and 54 are connected in series as a whole. The reverse osmosis membrane devices 51 and 52 used in the deionized water production system of the present embodiment are general ones used for pure water production and the like. Further, between the illustrated pump 55, reverse osmosis membrane devices 51 and 52, and EDI device 10, if necessary, a tank or a pump, an ion exchange resin device for softening or desalting, and decarboxylation A decarbonation tower, a membrane degassing device for the purpose of this, in addition, a drug injection facility, etc. may be suitably added and arranged.

As raw water, tap water, well water, river water, industrial water, etc. are used. The EDI apparatus 10 is supplied with supply water other than the water to be treated, as will be described later. The feed water may be, for example, permeated water obtained from the reverse osmosis membrane device, or may be water treated by the EDI device, ie, deionized water. Here, two stages of reverse osmosis membrane devices 51 and 52 are provided. However, as shown in FIG. 2 , only one stage of reverse osmosis membrane devices 52 may be provided at the front end of the EDI device 10 . .

In order to obtain deionized water with a lower impurity concentration than the system shown in Fig. 1, EDI devices may be connected in series in two stages. FIG. 3 shows that, in the deionized water production system shown in FIG. 1 , an additional EDI device 15 is disposed between the reverse osmosis membrane device 52 and the EDI device 10 . As the EDI device 15, a thing having the same configuration as the EDI device 10 can be used, or a thing having a different configuration can also be used. The permeated water of the reverse osmosis membrane device 52 is supplied to the desalination chamber 23 of the EDI device 15 , and the water flowing from the desalination chamber 23 of the EDI device 15 is the treated water of the EDI device 10 . supplied to the desalination chamber. Further, between the illustrated pump 55, reverse osmosis membrane devices 51 and 52, and EDI devices 10 and 15, if necessary, a tank or a pump, an ion exchange resin device for softening or desalting; A decarboxylation tower for the purpose of decarboxylation, a membrane degassing device, in addition, a drug injection facility, etc. may be suitably added and arranged.

In the case of the structure shown in FIG. 3, the electrical conductivity of the to-be-processed water supplied to the EDI apparatus 10 used as the 2nd stage has already become an extremely small value, for example, 1 microS/cm or less. In the case of producing deionized water using an EDI device, the operating voltage of the EDI device tends to increase when the conductivity of the water to be treated is low. However, as the EDI device 10 at the rear stage, the EDI device described later according to the present invention is used. By using it, the operating voltage of this EDI device 10 can be kept low. Since the conductivity of the water to be treated supplied to the additional EDI device 15 serving as the first stage is relatively large, a general EDI device can be used instead of the EDI device described later as the additional EDI device 15 .

In each of the deionized water production systems shown in Figs. 1, 2 and 3, the conductivity of the water to be treated to the EDI device 10 is, for example, 10 µS/cm or less, preferably 5 µS/cm or less, and 3 µS It is more preferable that it is /cm or less, and it is still more preferable that it is 1 microseconds/cm or less.

Next, the EDI apparatus 10 according to the present invention used in the deionized water production system described above will be described. In the EDI device 10, between the anode chamber 21 provided with the anode 11 and the cathode chamber 25 provided with the cathode 12, sequentially from the side of the anode chamber 21, the enrichment chamber ( 22), a desalination chamber 23 and a concentration chamber 24 are provided. The anode chamber 21 and the enrichment chamber 22 are adjacent to each other with a cation exchange membrane 31 interposed therebetween, and the enrichment chamber 22 and the desalting chamber 23 are adjacent to each other with an anion exchange membrane 32 interposed therebetween, and a desalting chamber. 23 and the enrichment chamber 24 are adjacent to each other with a cation exchange membrane 33 interposed therebetween, and the enrichment chamber 24 and the cathode chamber 25 are adjacent to each other with an anion exchange membrane 34 interposed therebetween. Accordingly, the desalting chamber 23 is partitioned by the anion exchange membrane 32 positioned on the side facing the anode 11 and the cation exchange membrane 33 positioned on the side facing the cathode 12 . In the desalting chamber 23, at least one of an anion exchanger and a cation exchanger is filled. In the example shown here, in the desalting chamber 23, an anion exchanger and a cation exchanger are mutually mixed, ie, it is filled with a mixed bed structure. Further, in the EDI device 10 , a cation exchanger is filled in the anode chamber 21 , and an anion exchanger is filled in the concentration chambers 22 , 24 and the cathode chamber 25 . As an anion exchanger here, an anion exchange resin is used, for example, and a cation exchange resin is used as a cation exchanger, for example. In addition, the anode chamber 21, the concentrating chambers 22 and 24, and the cathode chamber 25 are not necessarily filled with an anion exchanger or a cation exchanger. FIG. 4 schematically shows a cross-sectional configuration of an EDI device 10 used in the deionized water production system shown in FIG. 1 . In Fig. 4, wishes drawn in the electrode chambers 21 and 25, the enrichment chambers 22 and 24, and the desalination chamber 23 indicate anion exchangers and cation exchangers filled in those chambers. In Fig. 4, the anion exchanger and the anion exchange membrane are provided with the same hatching, and the cation exchanger and the cation exchange membrane are provided with the same hatching, but the anion exchanger and the cation exchanger are provided with different hatching. are drawn separately. The distinction between the anion exchanger and the cation exchanger by the hatching and the distinction between the anion exchange membrane and the cation exchange membrane are common in each drawing attached to this specification.

In the following description, the anion exchanger and the cation exchanger are collectively referred to as an ion exchanger, and the anion exchange membrane and the cation exchange membrane are collectively referred to as an ion exchange membrane. Accordingly, the ion exchanger is at least one of an anion exchanger and a cation exchanger, and the ion exchange membrane is at least one of an anion exchange membrane and a cation exchange membrane.

In addition, in the EDI apparatus 10 , in the desalting chamber 23 , at least a part of an ion exchanger and at least a part of an ion exchange membrane (anion exchange membrane 32 and cation exchange membrane 33 ) provided in the desalting chamber 23 . Particles containing a polyvalent metal are adsorbed on at least one surface of the Particles containing a polyvalent metal as used herein include a polyvalent metal, that is, a metal element having an ionic value of 2 or more when it becomes a cation, and is adsorbed to an anion exchanger, a cation exchanger, an anion exchange membrane or a cation exchange membrane, and After being adsorbed, it is a particle that does not easily break off mechanically. The polyvalent metal used here is not particularly limited as long as it acts as a catalyst for water dissociation, and one type of metal or multiple types of metals may be contained. As a metal element used as a polyvalent metal, magnesium, calcium, aluminum, chromium, manganese, iron, nickel, etc. are mentioned, for example. As described above, "particles containing a polyvalent metal" are considered to act as catalysts for water dissociation, and therefore, hereinafter, unless otherwise specified, "particles containing a polyvalent metal" are only referred to as "catalyst particles".

The catalyst particles are not particularly limited as long as they are easily adsorbed to the surface of an anion exchanger, cation exchanger, anion exchange membrane, or cation exchange membrane. When the catalyst particles are inorganic materials, it is preferable that the catalyst particles are inorganic ion exchange materials from the viewpoint of easiness of adsorption. An inorganic ion exchange material is an inorganic substance having the ability to exchange ion species by taking in ions in an electrolyte solution in contact with it and releasing ions it possesses instead, that is, an ion exchange capability. Catalyst particles, which are inorganic ion exchange materials, are easily adsorbed on the surface of anion exchangers, cation exchangers, anion exchange membranes or cation exchange membranes. On the other hand, it is estimated that it is because it is adsorb|sucking through the ion exchange group which exists on these surfaces.

As an example of the catalyst particle which is an inorganic ion exchange material, the silicate containing a polyvalent metal can be used preferably, As such a silicate, For example, aluminum silicate, magnesium silicate, calcium silicate, calcium silicate magnesium, various aluminosilicates, Various silicate minerals are mentioned, One or more of these can be used individually or in mixture. Among them, silicate minerals are excellent in chemical stability and particularly strongly adsorbed to an anion exchanger or an anion exchange membrane, so that more stable performance can be expected. In addition, since silicate minerals are included in natural ore, there are many options and it is advantageous in terms of cost. Examples of such silicate minerals include fluorite, talc, kaolinite, and zeolite. Among them, sepiolite (CAS number (Chemical Abstract Service registry number): 63800-37-3, composition formula: Mg ₈ Si ₁₂ O ₃₀₎ (OH) ₄ (OH ₂ ) ₄ 8H ₂ O), wollastonite (CAS number: 13983-17-0, compositional formula: CaSiO ₃ ), attapulgite (CAS number: 12174-11-7, compositional formula) : because of _{(Mg, Al) 5 Si 8} O 20 · 4H 2 O) , etc. has a high adsorbability, and is used more suitably. As the catalyst particles, it is more preferable to use those made of at least one of attapulgite, sepiolite and wollastonite. Moreover, it is known that attapulgite, sepiolite, and wollastonite are in the form of needle-like particles. The reason that silicate minerals are easily adsorbed to anion exchangers is that an anion exchanger such as an amino group or a quaternary ammonium group contained in the anion exchanger is electrostatically attached to, for example, a hydroxyl group or an oxygen atom present on the surface of the silicate mineral. It is presumed that they are attracted to each other.

The adsorption of the catalyst particles to the ion exchanger or the ion exchange membrane can be easily performed, for example, by immersing the ion exchanger or the ion exchange membrane in water in which the catalyst particles are dispersed. In addition, by supplying water in which the catalyst particles are dispersed to the desalting chamber of the existing EDI device, the catalyst particles can be adsorbed to the ion exchanger or ion exchange membrane in the desalting chamber. Therefore, it is easy to convert an existing EDI device into an EDI device according to the present invention, and manufacturing deionized water after converting an existing EDI device into an EDI device according to the present invention is also included in the scope of the present invention. will be.

The particle diameter of the catalyst particles is not particularly limited. The particle diameter of each catalyst particle can be calculated|required by observing the catalyst particle at a magnification of about 1000-20000 times with a scanning electron microscope (SEM), for example, and measuring in the obtained phase. When the shape of the catalyst particles is not a perfect sphere, the maximum diameter is taken as the particle diameter. For example, when the catalyst particles are needle-shaped particles, the length of the major axis is the particle diameter. The range of the particle diameter of the catalyst particle is the range from the minimum value to the maximum value of the particle diameter measured by measuring the particle diameter of the catalyst particle in 10 SEM images with different observation fields. In the present invention, it is preferable to use catalyst particles having a particle diameter of, for example, 0.01 µm or more and 100 µm or less, and more preferably use catalyst particles having a particle diameter of 0.02 µm or more and 10 µm or less.

If the particle diameter of the catalyst particles is too large, the ion exchanger or ion exchange membrane cannot be properly adsorbed and fixed to the surface, and the distance between the interfaces of different ion exchange substances is too wide, so that the water dissociation reaction cannot be sufficiently promoted. there is a possibility that there will be no On the other hand, if the particle diameter of the catalyst particles is too small, there is a possibility that the catalyst particles densely cover the surface of the ion exchanger or ion exchange membrane, thereby causing problems such as inhibiting ion exchange reaction or ion movement in the ion exchanger or ion exchange membrane. .

Here, an ion exchanger filled in the desalting chamber 23 will be described. The type of the ion exchanger that can be filled in the desalting chamber 23 is not limited to a specific one, but, as exemplified above, an ion exchange resin is preferable. The ion exchange resin as used herein is a synthetic resin in which a functional group having ion exchange ability, that is, an ion exchange group, is introduced into a polymer matrix having a three-dimensional network structure. Ion exchange resins commonly used are spherical particles having a particle diameter of about 0.4 to 0.8 mm. Examples of the polymer matrix of the ion exchange resin include a styrene-divinylbenzene copolymer called “styrene-based” and an acrylic acid-divinylbenzene copolymer called “acrylic acid-based”.

The ion exchange resin is roughly divided into a cation exchange resin in which an ion exchange group is acidic and an anion exchange resin in which an ion exchange group is basic, and depending on the type of ion exchange group to be introduced, a strongly acidic cation exchange resin, a weakly acidic cation exchange resin, a strongly basic anion exchange resins, weakly basic anion exchange resins, and the like. Strongly basic anion exchange resins include, for example, those having a quaternary ammonium group as an ion exchange group, and weakly basic anion exchange resins include, for example, primary amines, secondary amines or tertiary amines. There is something to have as an exchanger. Examples of the strongly acidic cation exchange resin include those having a sulfonic acid group as an ion exchange group, and examples of the weakly acidic cation exchange resin include those having a carboxyl group as an ion exchange group. As the ion exchange resin to be filled in the desalting chamber, any of these types can be used, but it is preferable to select a combination of the ion exchange resin and the catalyst particles such that the catalyst particles are adsorbed to the ion exchange groups of the ion exchange resin.

The amount of catalyst particles adsorbed to the ion exchanger in the desalting chamber 23 is preferably 0.0001 vol% or more and less than 1 vol%, and 0.0125 vol% or less, when expressed as a volume ratio where the volume of the ion exchanger is 100%. It is more preferable to If the adsorption amount of the catalyst particles is too large, the catalyst particles may rather inhibit the ion exchange reaction or ion movement in the EDI device 10 .

Next, the production of deionized water by the EDI apparatus 10 shown in FIG. 4 will be described.

As in the case of the conventional EDI device, supply water is passed through the anode chamber 21 , the enrichment chambers 22 , 24 and the cathode chamber 25 , and a DC voltage is applied between the anode 11 and the cathode 12 . In one state, the water to be treated flows through the desalination chamber 23 . When the water to be treated is passed through the desalination chamber 23 , the ion components in the water to be treated are adsorbed to the ion exchanger in the desalination chamber 23 , deionization is performed, and the treated water is discharged from the desalination chamber 23 . As a result, deionized water flows out. At this time, in the desalination chamber 23, a dissociation reaction of water occurs at the interface between different ion-exchangeable substances by an applied voltage, and hydrogen ions and hydroxide ions are generated, and by the hydrogen ions and hydroxide ions, the desalination chamber 23 first The ion component adsorbed to the ion exchanger inside is ion-exchanged and released from the ion exchanger. Among the liberated ion components, anions are moved to the concentration chamber 22 near the anode via the anion exchange membrane 32 , and discharged as concentrated water from the concentration chamber 22 , and the cations pass through the cation exchange membrane 33 . It moves to the concentrating chamber 24 on the side closer to the negative electrode, and is discharged as concentrated water from the concentrating chamber 24 . As a result, the ion components in the to-be-treated water supplied to the desalination chamber 23 move to the concentration chambers 22 and 24 and are discharged, and at the same time, the ion exchanger in the desalination chamber 23 is also regenerated. Further, electrode water is discharged from the anode chamber 21 and the cathode chamber 25 .

In the EDI device 10 shown in FIG. 4, as described above, the surface of at least one of the ion exchanger, the anion exchange membrane 32 and the cation exchange membrane 33 installed in the desalting chamber 23 contains a polyvalent metal. Particles, that is, catalyst particles are adsorbed. The catalyst particles exist at the interface between different ion-exchangeable substances in the desalting chamber 23, but the polyvalent metal contained in the catalyst particles acts as a catalyst for accelerating the dissociation reaction of water, so this EDI device ( In 10), the dissociation reaction of water can be efficiently performed. Accordingly, the regeneration of the ion exchanger in the demineralization chamber 23 can also be efficiently performed, and high-purity deionized water can be produced with low power while suppressing the voltage applied to the EDI device 10 . Further, as the applied voltage can be lowered, the device can be operated at a high current density in the desalination chamber 23 , for example, a current density of 0.3 A/dm ² or more and 10 A/dm ^{2 or less.}

5A and 5B schematically show the dissociation reaction of water by catalyst particles. Here, it is assumed that the catalyst particles 43 are adsorbed to the anion exchanger 42 . When the interface of the heterogeneous ion-exchange material is constituted by the cation exchanger 41 and the anion exchanger 42, as shown in FIG. 5A, dissociation of water at this interface is promoted, and anion exchange Hydrogen ions are efficiently generated on the side of the sieve 42 and hydrogen ions are generated on the side of the cation exchanger 41 . Similarly, at the interface between the anion exchanger 42 and the cation exchange membrane 33, as shown in FIG. 5B, hydroxide ions are efficiently generated on the anion exchanger 42 side and hydrogen ions are efficiently generated on the cation exchange membrane 33 side. do. According to the EDI device 10, dissociation of water at the interface between the ion exchange membrane and the ion exchanger can also be promoted.

As mentioned above, although the basic structure of the EDI apparatus 10 based on this invention was demonstrated, this invention is widely applicable to EDI apparatus of various structures. Hereinafter, a configuration example of an EDI device to which the present invention can be applied will be described. In either case, particles containing a polyvalent metal, ie, catalyst particles, are adsorbed to at least the ion exchanger or ion exchange membrane of the desalting chamber 23 . The EDI apparatus described below can be used as the EDI apparatus 10 in the deionized water production system shown in either of FIGS. 1, 2 and 3 .

6 shows another form of an EDI device according to the present invention. As described above, with the EDI device, a basic configuration (i.e., cell set) consisting of [concentration chamber|anion exchange membrane (AEM)|demineralization chamber|cation exchange membrane (CEM)|concentration chamber] can be juxtaposed between the anode and the cathode. can In this case, adjacent enrichment chambers may be shared between adjacent cell sets. The EDI device shown in FIG. 6 is the device shown in FIG. 4, in which a plurality of cell sets are arranged in this way, and consists of an anion exchange membrane 32 , a desalting chamber 23 , a cation exchange membrane 33 , and a concentration chamber 24 . One cell set is constituted, and N cell sets are arranged between the enrichment chamber 22 and the cathode chamber 25 closest to the anode chamber 21 . Here, N is an integer greater than or equal to 1. The anode chamber 21 is filled with a cation exchange resin (CER), the enrichment chambers 22 and 24 and the cathode chamber 25 are filled with an anion exchange resin (AER), and the desalination chamber 23 is filled with an anion exchange resin and A cation exchange resin is charged in a mixed bed (MB). The anode chamber 21 is not supplied with water from the outside, but the outlet water from the cathode chamber 25 is supplied to the anode chamber 21 . In addition, unlike the one shown in FIG. 4, the flow direction of the water in the desalination chamber 23 is countercurrent with respect to the flow direction of the water in the concentrating chambers 22 and 24 on both sides.

7 shows another form of an EDI device according to the present invention. This EDI device is similar to that shown in Fig. 4, but in the desalting chamber 23, an anion exchange resin is disposed in a region close to the inlet of the water to be treated, and an anion exchange resin and a cation exchange resin are disposed in a region close to the outlet. It is installed in a mixed phase. As a matter of course, assuming that one cell set is composed of the anion exchange membrane 32 , the desalting chamber 23 , the cation exchange membrane 33 , and the concentration chamber 24 , this cell set is concentrated closest to the anode chamber 21 . N pieces can be arranged between the chamber 22 and the cathode chamber 25 . Here again, N is an integer greater than or equal to 1.

The EDI apparatus shown in Fig. 8 is the same as that shown in Fig. 7, but the desalination chamber 23 is divided into four regions according to the flow direction of the water therein, and the positive ions are sequentially obtained from the position of the inlet of the to-be-treated water. An ion exchange resin is disposed in each region so as to be placed on an exchange resin, an anion exchange resin, a cation exchange resin, and an anion exchange resin. That is, in the EDI device shown in FIG. 8 , the desalting chamber 23 is provided with an ion exchanger having a multilayer structure in which cation exchange resin layers and anion exchange resin layers are alternately arranged along the flow direction of water. Further, in the EDI device shown in Fig. 8, unlike that shown in Fig. 7, the flow direction of water in the demineralization chamber 23 is countercurrent to the flow direction of water in the enrichment chambers 22 and 24 on both sides thereof. have.

The EDI apparatus shown in FIG. 9 is the same as that shown in FIG. 7, but the desalination chamber 23 is divided into three regions according to the flow direction of water therein, and negative ions are An ion exchange resin is disposed in each region so as to be placed as an exchange resin, a cation exchange resin, and an anion exchange resin. Also in the EDI device shown in Fig. 9, the ion exchanger in the desalting chamber 23 has a multi-layered configuration.

In the EDI apparatus according to the present invention, in each desalting chamber, an intermediate ion exchange membrane (IIEM) is provided between the anion exchange membrane on the anode-facing side and the cation exchange membrane on the cathode-facing side, and the desalting chamber is separated by the intermediate ion exchange membrane. The first demineralization chamber and the second demineralization chamber are divided, and the water to be treated is supplied to one demineralization chamber among the first demineralization chamber and the second demineralization chamber, and the water flowing out from one demineralization chamber is discharged from the other demineralization and demineralization chamber. The first and second demineralization chambers may be disposed in communication with each other to flow into the demineralization chamber. As the intermediate ion exchange membrane, both an anion exchange membrane and a cation exchange membrane can be used. At this time, if the demineralization and demineralization chamber close to the positive electrode is the first demineralization chamber and the demineralization and demineralization chamber close to the cathode is the second demineralization chamber, the first demineralization chamber is filled with at least an anion exchanger, and the second demineralization and demineralization chamber is The yarn is at least filled with a cation exchanger. Catalyst particles, respectively, at least one of an ion exchanger in the demineralization chamber, an intermediate ion exchange membrane, an anion exchange membrane provided on a side facing the anode of the first demineralization and demineralization chamber, and a cation exchange membrane provided on a side facing the cathode of the second demineralization and demineralization chamber is adsorbed to

FIG. 10 shows an example of an EDI apparatus in which the desalting chamber is divided into two demineralization chambers by an intermediate ion exchange membrane in this way. This EDI apparatus has a configuration in which each demineralization chamber 23 in the EDI apparatus shown in FIG. 6 is partitioned into a first demineralization chamber 26 and a second demineralization chamber 27 by an intermediate ion exchange membrane 36. has In this example, as the intermediate ion exchange membrane 36, an anion exchange membrane is used. The first demineralization and desalination chamber 26 closer to the anode 11 is filled with an anion exchange resin, and the second demineralization and demineralization chamber 27 closer to the cathode 12 is filled with a cation exchange resin. The to-be-treated water is first supplied to the second demineralization and demineralization chamber 27, and the outlet water from the second demineralization and demineralization chamber 27 becomes co-current with the flow of water in the second demineralization and demineralization chamber 27. It is supplied to the demineralization chamber 26, and from the 1st demineralization and demineralization chamber 26, deionized water is obtained as water after treatment. With respect to the flow of water in the first and second demineralization and demineralization chambers 26 and 27 , the flow of water in the anode chamber 21 , the enrichment chambers 22 , 24 and the cathode chamber 25 is countercurrent.

FIG. 11 schematically shows the dissociation reaction of water by catalyst particles in the EDI apparatus shown in FIG. 10 . Here, it is assumed that the catalyst particles 43 are adsorbed to the intermediate ion exchange membrane 36 which is an anion exchange membrane. When the interface of the heterogeneous ion exchange material is constituted by the cation exchanger 41 and the intermediate ion exchange membrane 36, the dissociation of water at this interface is promoted, as shown in the figure, and the intermediate ion exchange membrane ( Hydroxide ions are efficiently generated on the side of 36) and hydrogen ions are efficiently generated on the side of the cation exchanger (41).

12 shows another example of the EDI device in which the desalting chamber is divided into two demineralization chambers by an intermediate ion exchange membrane in this way. In this EDI apparatus, each demineralization chamber 23 in the EDI apparatus shown in FIG. 7 is connected to a first demineralization chamber 26 and a cathode 12 on the side closer to the anode 11 by an intermediate ion exchange membrane 36. It is divided into a second demineralization and demineralization chamber 27 on the side closer to , and the first demineralization chamber 26 is filled with an anion exchange resin, and an anion exchange resin and a cation exchange resin are added to the second demineralization and demineralization chamber 27 It is filled with soul. The to-be-treated water is supplied to the first demineralization and demineralization chamber 26 , and the outlet water of the first demineralization and demineralization chamber 26 is transferred to the second demineralization and demineralization chamber 27 , and deionized water from the second demineralization and demineralization chamber 27 . is obtained For the intermediate ion exchange membrane 36, for example, an anion exchange membrane is used.

In the EDI apparatus shown in Fig. 13, in the second demineralization chamber 27 in the EDI apparatus shown in Fig. 12, the anion exchange resin and the cation exchange resin are not provided in a mixed phase, but in the second demineralization chamber 27 ), the cation exchange resin is arranged in the region close to the inlet, and the anion exchange resin is arranged in the region close to the outlet.

[Example]

Hereinafter, the present invention will be described in more detail based on Examples and Comparative Examples. In Examples and Comparative Examples, the deionized water production system or EDI device having the above-described configuration was assembled, and these deionized water production systems or EDI devices were actually operated. In these Examples and Comparative Examples, by selecting whether or not to use catalyst particles during granulation, the effect of the present invention by the presence or absence of catalyst particles was confirmed.

[Example 1 and Comparative Example 1]

The EDI apparatus used in Example 1 and Comparative Example 1 is the EDI apparatus shown in FIG. 6 , an anion exchange membrane (AEM) 32 and a desalination chamber 23 between the anode chamber 21 and the cathode chamber 25 . ), the cation exchange membrane (CEM) 33 and the concentration chamber 24, the number of repetitions N of the basic configuration (cell set) being set to 3. The anode chamber 21 is filled with a cation exchange resin (CER), each of the concentration chambers 22 and 24 and the cathode chamber 25 is filled with an anion exchange resin (AER), and the desalination chamber 23 is filled with a cation exchange resin. and an anion exchange resin were charged as a mixed phase (MB). As the cation exchange resin, Amberlite (registered trademark) IR120B, a styrene-based strongly acidic cation exchange resin having a sulfonic acid group as an ion exchange group (manufactured by Dow Chemical, reference value of apparent density: about 840 g/L) was used, and anion exchange As the resin, Amberlite (registered trademark) IRA402BL (manufactured by Dow Chemical, reference value of apparent density: about 715 g/L), which is a styrene-based strongly basic anion exchange resin having a quaternary ammonium group as an ion exchange group, was used. SELEMION (registered trademark) CME (manufactured by AGC Engineering) was used for the cation exchange membrane, and SELEMION (registered trademark) AME (manufactured by AGC Engineering) was used for the anion exchange membrane. Both the cation exchange membrane and the anion exchange membrane used herein are heterogeneous ion exchange membranes. The heterogeneous ion-exchange membrane is a finely divided granular ion-exchange resin, solidified with a thermoplastic or thermosetting binder, and molded into a membrane shape, and the mechanical strength is generally superior to that of a homogeneous ion-exchange membrane. In contrast, the homogeneous ion exchange membrane is formed by forming the ion exchange resin itself into a membrane shape.

In Comparative Example 1, an anion exchange resin on which catalyst particles were not adsorbed was used for the desalting chamber 23, but in Example 1, the anion exchange resin was previously treated with catalyst particles by the following treatment method and treated The subsequent anion exchange resin was mixed with a cation exchange resin, and the desalting chamber 23 was filled. As the particles used for treatment with the anion exchange resin, in Example 1, the anion exchange resin was treated using particles adsorbed to the anion exchange resin, and as a result, the particles were adsorbed on the surface of the anion exchange resin. In either case, as the ion exchange resin to be filled in the anode chamber 21, the concentration chambers 22 and 24, and the cathode chamber 25, a resin that does not adsorb particles was used.

Next, the particle|grains used in Example 1 are demonstrated concretely.

In Example 1, attapulgite, a silicate mineral containing polyvalent metal magnesium and aluminum, was used as catalyst particles. When observed at 20000 times magnification by SEM, the particle diameter of the attapulgite used in Example 1 was in the range of 0.02 to 10 µm. Since attapulgite is a needle-shaped particle, the major axis was taken as the particle diameter. As measured by the same SEM image, the range of the minor diameter of the used attapulgite was 0.01 to 1 µm. The minor axis is a length in a direction orthogonal to the major axis at the central position of the major axis. The attapulgite used in Example 1 (CAS No: 12174-11-7) is a general formula (Mg, Al) ₅ Si ₈ O ₂₀ ·4H ₂ O, wherein the ratio of silicon, magnesium and aluminum is In terms of the mass ratio of silicon dioxide (SiO ₂ ), magnesium oxide (MgO), and aluminum oxide (Al ₂ O _{3 ), SiO 2} :MgO:Al ₂ O ₃ =65:13:12.

(Processing method of anion exchange resin)

After dispersing the particles in pure water and immersing the anion exchange resin therein, a treatment was performed to adsorb the particles to the surface of the anion exchange resin while stirring. The quantity of the particle|grains used at this time was 300 mg with respect to 1 L of anion exchange resin. The treated anion exchange resin was washed well with pure water and dried before use.

With respect to the treated anion exchange resin, attapulgite was quantified using inductively coupled plasma (ICP) emission spectroscopy. As a result, the mass of attapulgite adsorbed to the anion exchange resin was 190 per 1 L of the anion exchange resin. mg was. Since the specific gravity of attapulgite is 2.4 g/cm 3 , the ratio of the adsorbed volume of attapulgite to the volume of the anion exchange resin is 0.0079%. The density of the anion exchange resin can be varied with the water content, but using the above-mentioned apparent density of 715 g/L, the mass ratio of attapulgite to the anion exchange resin becomes 0.027 mass%.

The specifications of the EDI apparatus in Example 1 and Comparative Example 1, and operating conditions, such as water flow rate, an applied voltage, and the water quality of supply water, are as follows. In addition, in the following description, the flow rate of to-be-processed water is the total amount of flow rates of the to-be-processed water supplied to the plurality of desalination chambers 23 in EDI apparatus, and the flow rate of electrode chamber is the anode chamber 21 and the cathode chamber ( 25), and the concentrated water flow rate is the sum of the flow rates of the feed water supplied to the plurality of enrichment chambers 22 and 24.

Demineralization chamber: dimensions 300 × 100 × 10 mm multi-phase (MB) filling (volume ratio: cation exchange resin / anion exchange resin = 1/1)

Concentration chamber: dimension 300 × 100 × 5 mm filled with anion exchange resin (AER)

·Anode chamber: 300 × 100 × 4 mm cation exchange resin (CER) filling

·Cathode chamber: dimension 300 × 100 × 4 mm filled with anion exchange resin (AER)

・Water flow rate: 180ℓ/h

Concentrated water flow rate: 30ℓ/h

・Electrode water flow rate: 10ℓ/h

Supply water and untreated water: Reverse osmosis membrane (RO) permeated water, conductivity 5±1 μS/cm

·Applied current value: 0.9A

·Applied current density: 0.3A/dm ²

The devices of Example 1 and Comparative Example 1 were operated for 1000 hours under the above conditions, and the operating voltage and specific resistance of the obtained deionized water were compared. A result is shown in Table 1.

Example 1 Comparative Example 1 Particles adsorbed to anion exchange resin attapulgite none Operating voltage [V] 11.9 23.2 Specific resistance [㏁ cm] 17.1 9.0

When Example 1 was compared with Comparative Example 1 in which no catalyst particles were used, the basic effect of the present invention could be confirmed because Example 1 clearly showed better operating voltage and water quality.

In Example 1, catalyst particles were adsorbed to the anion exchange resin used in the desalination chamber, but all or part of the ion exchange resin used in each electrode chamber or concentrating chamber constituting the EDI device was allowed to adsorb the catalyst particles. You can do it.

[Examples 2-1, 2-2 and Comparative Example 2]

The EDI apparatus used in Examples 2-1 and 2-2 and Comparative Example 2 was the EDI apparatus shown in FIG. 10, the anion exchange membrane 32 between the anode chamber 21 and the cathode chamber 25, The number of repetitions N of the basic configuration (cell set) consisting of 1 desalting chamber 26, intermediate ion exchange membrane (IIEM) 36, second demineralization chamber 27, cation exchange membrane 33 and enrichment chamber 24 is it was done with 3. A cation exchange resin was filled in the anode chamber 21 and the second demineralization chamber, and an anion exchange resin was filled in each of the concentration chambers 22 and 24 , the first demineralization chamber 26 and the cathode chamber 25 . An anion exchange membrane was used for the intermediate ion exchange membrane 36 dividing the first demineralization chamber 26 and the second demineralization and demineralization chamber 27 . As an anion exchange resin, a cation exchange resin, an anion exchange membrane, and a cation exchange membrane, the thing similar to that used in Example 1 was used, respectively. However, catalyst particles are not adsorbed to the anion exchange resin. In particular, in Examples 2-1 and 2-2, the catalyst particles referred to in the present invention were adsorbed to the anion exchange membrane in advance by the following treatment method, and the anion exchange membrane to which the catalyst particles were adsorbed was used as the intermediate ion exchange membrane 36 . Catalyst particles are not adsorbed to the anion exchange membranes 32 and 34 and the cation exchange membranes 31 and 33 . As the catalyst particles, attapulgite of the same standard as used in Example 1 was used. In Comparative Example 2, adsorption of the catalyst particles to the anion exchange membrane was not performed.

(Processing method of anion exchange membrane)

0.2 g of catalyst particles were dispersed per 1 liter of pure water, the anion exchange membrane was immersed therein, and the catalyst particles were adsorbed on the surface of the anion exchange membrane while stirring. The treated anion exchange membrane was washed well with pure water and dried before use.

The specifications of the EDI apparatus in Examples 2-1 and 2-2 and Comparative Example 2, and operating conditions such as water flow rate, applied voltage, and water quality of supply water are as follows.

· First demineralization chamber: dimension 300 × 100 × 10 mm filled with anion exchange resin (AER)

· Second demineralization chamber: 300 × 100 × 10 mm cation exchange resin (CER) filling

-Applied current value: 0.9A (Example 2-1, Comparative Example 2), 30A (Example 2-2)

-Applied current density: 0.3A/dm ² (Example 2-1, Comparative Example 2), 10A/dm ² (Example 2-2)

- The concentration chamber, the anode chamber, the cathode chamber, the to-be-treated water flow rate, the concentrated water flow rate, the electrode water flow rate, the feed water and the to-be-treated water were the same as in Example 1.

The devices of Examples 2-1 and 2-2 and Comparative Example 2 were operated for 1000 hours under the above conditions, and the operating voltage and specific resistance of the obtained deionized water were compared. A result is shown in Table 2.

Example 2-1 Example 2-2 Comparative Example 2 Particles adsorbed to anion exchange resin attapulgite attapulgite none Applied voltage [V] 0.9 30 0.9 Applied current density [A/dm ² ] 0.3 10 0.3 Operating voltage [V] 12.1 58.1 189.3 Specific resistance [㏁ cm] 16.3 17.4 15.5

Comparing Example 2-1 with Comparative Example 2, Example 2-1 showed better operating voltage and water quality, so even if the demineralization chamber was divided into two demineralization chambers by an intermediate ion exchange membrane, It was confirmed that the effect of the present invention was obtained as in the case where the desalting chamber was not partitioned. Furthermore, it was also confirmed that the same effect could be obtained by adsorbing catalyst particles not only to the ion exchanger filled in the desalting chamber, but also to the ion exchange membrane partitioning the desalting chamber. Comparing Example 2-2 with Comparative Example 2, in Example 2-2 ^{, the operating voltage and water quality were both good despite the high current density setting of 10 A/dm 2} , so that at least the current density was 0.3 to 10 A/dm. ^In the range of 2, it turns out that the remarkable effect by this invention is acquired.

In Examples 1, 2-1 and 2-2 described above, as an example, the results obtained when catalyst particles were adsorbed to an anion exchange resin or an anion exchange membrane were shown, but catalyst particles adsorbed to a cation exchange resin or a cation exchange membrane were selected. Needless to say, the same effect is obtained even in this case. In addition, although all of the ion exchange membranes used in the above-mentioned Examples were heterogeneous ion exchange membranes, it goes without saying that the same effect is obtained even when a homogeneous ion exchange membrane is used. Incidentally, although the ion exchange membrane subjected to a treatment for adsorbing catalyst particles was used in the above-mentioned examples, even if an ion exchange membrane molded using an ion exchange resin to which catalyst particles have been adsorbed in advance is used, the same results as those shown in the above-mentioned examples are used. Needless to say, the effect is obtained. The use of an ion exchange membrane molded using an ion exchange resin to which catalyst particles have been adsorbed in advance is also included in the scope of the present invention.

Similarly, in Examples 2-1 and 2-2 described above, among the anion exchange membranes used in the EDI apparatus, the catalyst particles were adsorbed on the entire surface of the intermediate ion exchange membrane that further divides the desalting chamber into a demineralization chamber, but in the EDI apparatus The catalyst particles may be adsorbed to other ion exchange membranes as well, or the catalyst particles may be adsorbed only on one side of the ion exchange membrane or a specific location of the ion exchange membrane. In particular, in Examples 2-1 and 2-2, an anion exchange membrane was selected as an intermediate ion exchange membrane for partitioning the desalting chamber into a demineralization chamber, but it goes without saying that the effect of the present invention is obtained even when the cation exchange membrane is used as an intermediate ion exchange membrane. . In that case, it is possible to appropriately select whether the catalyst particles are adsorbed to the cation exchange membrane or the catalyst particles are adsorbed to the anion exchange resin filled in one of the demineralization and desalination chambers.

[Example 3 and Comparative Example 3]

In Example 3 and Comparative Example 3, the EDI apparatus of Example 1 and Comparative Example 1 has the same configuration, and the dimensions of the desalting chamber, the enrichment chamber, the anode chamber and the cathode chamber and the ion exchange resin filled in them are also the same as in Example 1 The same, but an EDI device with the number of repetitions N of the cell set equal to 1 was used. In the apparatus of Example 3, the catalyst particles used were of the same specifications as those used in Example 1, and the treatment method of the anion exchange resin was the same as that of Example 1.

Pure water having a conductivity of 1 µS/cm or less was used as the water to be treated and the feed water, and the flow rate of the water to be treated was 60 L/h, the flow rate of the concentrated water was set to 10 L/h, and the flow rate of the electrode water was set to 10 L/h. Then, a voltage was applied to the EDI device so as to achieve the applied current density shown in the column of applied current density in Table 3, and the operating voltage at the time when 1 hour had elapsed was calculated. A result is shown in Table 3. In Table 3, the arrow shows the behavior of the voltage at the time of measurement, the right arrow (→) shows that there was a stable tendency, and the upward arrow (↑) shows that there was an upward tendency. It is the same also in each table|surface after this that the behavior of a voltage was shown by an arrow.

Example 3 Comparative Example 3 Particles adsorbed to anion exchange resin attapulgite none Applied current density [A/dm ² ] 0.3 10 0.3 10 Operating voltage [V] 4.0→ 17→ 4.7↑ 30↑

From the results of Example 3 and Comparative Example 3, when the electrical conductivity of the water to be treated was low, the operating voltage increased in Comparative Example 3, and when the treatment with catalyst particles was not performed, the operating voltage was significantly increased, It has been found that operation at a practical applied current density cannot be performed.

[Example 4 and Comparative Example 4]

It is the same EDI device as Example 3 and Comparative Example 3, but as an ion exchanger filled in the desalting chamber, Amberlite (registered trademark) IRA402BL (Dow Only a reference value of apparent density manufactured by Chemical Corporation: about 715 g/L) was used, and the desalting chamber was set to have a single-phase configuration. The anion exchange resin used in Example 4 was previously treated in the same manner as in Example 1 to adsorb attapulgite on its surface. Using the same thing as in Example 3 as the water to be treated and the supplied water, and the flow rate of water passing through each room as in Example 3, a voltage was applied to the EDI device so that the applied current density shown in the column of the applied current density of Table 4 was obtained. was applied, and the operating voltage at the time when 1 hour had passed was calculated.

Example 4 Comparative Example 4 Particles adsorbed to anion exchange resin attapulgite none Applied current density [A/dm ² ] 0.3 0.8 0.3 0.8 Operating voltage [V] 4.3→ 5.3→ 61↑ 97↑

From the results of Example 4 and Comparative Example 4, as in Examples 1 and 3, when the single-phase ion exchange resin is filled, the catalyst particles are adsorbed, compared to when the multi-phase ion exchange resin is filled in the desalting chamber. It was found that the effect was particularly increased.

[Example 5]

The deionized water production system shown in FIG. 1 was assembled. As the EDI apparatus installed in the deionized water production system, the EDI apparatus used in Example 2-1, in which the number of repetitions N of the cell set was set to 5, was used. The ion exchange resin used, the ion exchange membrane, and the dimensions of each chamber were the same as in Example 2-1, but the catalyst particles were not adsorbed to the ion exchange membrane. Instead, with respect to the anion exchange resin used in the EDI apparatus, attapulgite was adsorbed in advance in the same manner as in Example 1, and in Example 2-1, the intermediate ion exchange membrane, which was the anion exchange membrane, was a cation exchange membrane. was changed to With this configuration, it becomes possible to promote a water dissociation reaction between the anion exchange resin having attapulgite adsorbed in the first demineralization chamber and the intermediate ion exchange membrane. In Example 5, the permeated water that passed through the two-stage reverse osmosis membrane device was used as the water to be treated in the EDI device, the electrical conductivity was 2±1 μS/cm, the sodium concentration was 100 μg/L, and the silica concentration was 50 μg. /L. As feed water, reverse osmosis membrane permeation water was used.

Water quality and operating voltage of deionized water flowing out of the EDI device with the target water flow rate being 800ℓ/h, concentrated water flow rate 80ℓ/h, electrode water flow rate 20ℓ/h, and applied current density being 0.5A/dm ^{2 .} was saved. A result is shown in Table 5.

Example 5 Water quality of deionized water [㏁ cm] 17.9 Applied current density [A/dm ² ] 0.5 Operating voltage [V] 19→

From the results of Example 5, it is possible to increase the current density in the EDI device even when the treated water having a low residual ion concentration and low conductivity is used, such as permeated water that has passed through a two-stage reverse osmosis membrane device, Moreover, it turned out that the flow volume of to-be-processed water can also become large. Comparing with the flow rate of to-be-processed water per cell set in EDI apparatus, the flow volume in Example 5 becomes 2.67 times the flow volume in Example 2. FIG.

[Example 6]

The deionized water production system shown in FIG. 3 was assembled. In this deionized water production system, two EDI devices 10 and 15 connected in series were used, but the EDI devices as described in Example 5 were used for either EDI devices 10 and 15. By having the membrane osmosis apparatuses 51 and 52 connected in two stages and using the EDI apparatuses 10 and 15 of the two stages, the to-be-treated water supplied to the EDI apparatus 10 of the second stage is, The specific resistance was 16±2 MΩ·cm (that is, the conductivity was 0.0635±0.008 μS/cm), and the electrical conductivity was very low, and the boron concentration was 1±0.2 μg/L. Reverse osmosis membrane permeation water is used as water supplied to the EDI apparatus 15 in the first stage, and water treated by the EDI apparatus 15 in the first stage, that is, 1 in the water supplied to the EDI apparatus 10 in the second stage. Deionized water from the EDI device 15 in the first stage was used.

The to-be-processed water flow rate in the EDI apparatus 15 of the 1st stage was 570 L/h, the concentrated water flow volume was 50 L/h, and the electrode water flow rate was 20 L/h, and the to-be-processed water flow rate in the EDI apparatus 10 of the 2nd stage was set to 20 L/h. The water flow rate was 500 L/h, the concentrated water flow rate was 50 L/h, and the electrode water flow rate was 20 L/h. The applied current densities in the EDI devices 10 and 15 were both 0.8 A/dm ² , and the water quality, boron concentration, and operating voltage of deionized water flowing from the EDI device 10 in the second stage were calculated. A result is shown in Table 6.

Example 6 Water quality of deionized water [㏁ cm] 18.2 Boron concentration in deionized water [ng/ℓ] less than 10 Applied current density [A/dm ² ] 0.8 Operating voltage [V] 14→

If you want to obtain deionized water with extremely low impurity concentration by connecting two EDI devices, there is concern that the operating voltage of the EDI device in the second stage will increase because the conductivity of the treated water supplied to the EDI device in the second stage is low. , from the results of Example 6, it was found that the increase in the operating voltage can be suppressed by using the EDI device according to the present invention. According to the present invention, it is possible to easily obtain deionized water of higher purity. In addition, although boron is known as an element difficult to remove by normal desalting treatment, according to Example 6, it was found that it can be removed to the extent of ng/L.

[Example 7]

The deionized water production system shown in FIG. 1 was assembled. The EDI apparatus shown in Fig. 8 was used as the EDI apparatus installed in the deionized water production system, and the number of repetitions N of the cell set was set to 5. The desalination chamber was configured as a multilayer structure so that the cation exchange resin layer, the anion exchange resin layer, the cation exchange resin layer, and the anion exchange resin layer were arranged in this order from the upstream side according to the flow of the water to be treated. The ion exchange membrane and ion exchange resin used were the same as in Example 1, and with respect to the anion exchange resin, attapulgite was adsorbed in advance by the same treatment method as in Example 1. The dimensions of the desalination chamber, the enrichment chamber, the anode chamber and the cathode chamber are the same as in the case of Example 1. In Example 7, the permeated water that passed through the two-stage reverse osmosis membrane device was used as the water to be treated in the EDI device, and the electrical conductivity was 1.5±0.2 μS/cm. As feed water, reverse osmosis membrane permeation water was used.

The target water flow rate was 1000 L/h, the concentrated water flow rate was 100 L/h, the electrode water flow rate was 20 L/h, the applied current density was 0.6 A/dm ² , and the operating voltage after 1000 hours of operation was measured. It was 18V.

Comparing Example 1 and Example 7, the operating voltage per cell set was 3.6V in Example 7, compared to 4.0V in Example 1. Although the current density in Example 7 is twice that of Example 1, and the conductivity of the water to be treated is lower in Example 7, the operating voltage per cell set is in Example 7 A value lower than 1 indicates that the remarkable effect of adsorbing attapulgite to the anion exchange resin is obtained by setting the structure of the ion exchanger in the desalting chamber to a multi-layer structure rather than a multi-phase structure. Moreover, compared with the flow rate of to-be-processed water per EDI apparatus cell set, the flow volume in Example 7 becomes 3.33 times the flow volume in Example 1. FIG.

10, 15: Electric deionized water production device (EDI device)
11: positive 12: negative
51, 52: reverse osmosis membrane device 21: anode chamber
22, 24: enrichment room 26: first demineralization room
27: second demineralization chamber 23: desalination chamber
25: cathode chamber 31, 33: cation exchange membrane (CEM)
32,34: anion exchange membrane (AEM) 36: intermediate ion exchange membrane (IIEM)
41: cation exchanger 42: anion exchanger
43: catalyst particles

Claims (1)

at least one desalting chamber is provided between the anode chamber with an anode and the cathode chamber with a cathode, wherein the desalting chamber is partitioned by an anion exchange membrane positioned on the anode-facing side and a cation exchange membrane positioned on the cathode-facing side; In the electric deionized water production apparatus in which at least one of an anion exchanger and a cation exchanger is charged in the desalting chamber,
adsorbing particles comprising a polyvalent metal to the surface of at least one of the anion exchange membrane, the cation exchange membrane, the anion exchanger, and the cation exchanger;
The electric deionized water production apparatus, characterized in that the volume of the particles relative to the volume of the anion exchanger and the cation exchanger is 0.0001% by volume or more and less than 1% by volume.

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