JP2008132492A - Electric demineralizer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric demineralizer having a novel construction with an excellent demineralization efficiency. <P>SOLUTION: This electric demineralizer comprises a demineralization chamber, a concentration chamber, and an electrode chamber in contact with an electrode, which have been partitioned by a plurality of ion exchange membranes, interposed between a cathode and an anode. In at least one of the demineralization chamber, the concentration chamber, and the electrode chamber, a plurality of layers of an anion exchange fiber material having an anion exchange function and/or layers of a cation exchange fiber material having a cation exchange function are stacked and disposed so as to cross each other in a water passing direction. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an improvement related to a so-called electric desalination apparatus, and provides an electric desalination apparatus having performance far exceeding that of a conventional electric desalination apparatus.

  The electric desalination equipment forms a concentrating chamber and a desalting chamber by arranging a cation exchange membrane and an anion exchange membrane between the cathode and anode electrodes, and uses a potential gradient as a driving source to treat the desalting chamber. Ion components are removed by moving and separating ions in the water through the ion exchange membrane to the concentration chamber.

  In FIG. 1, the conceptual diagram of the conventional typical electric desalination apparatus is shown. In the electric desalination apparatus shown in FIG. 1, an anion exchange membrane A and a cation exchange membrane C are alternately arranged between a cathode (−) and an anode (+) to form a desalination chamber and a concentration chamber. Yes. By further repeating the alternating arrangement of the anion exchange membrane and the cation exchange membrane, a plurality of desalting chambers and concentration chambers are alternately formed. If necessary, the desalting chamber and the concentration chamber are filled with an ion exchanger, which promotes the movement of ions in each chamber. Further, the sections in contact with the anode and the cathode at both ends are generally called an anode chamber and a cathode chamber, and serve to exchange electrons of current applied by a direct current.

In the operation of such an electric desalination apparatus, a voltage is applied to the anode and the cathode, and water is passed through the desalination chamber, the concentration chamber, and the electrode chamber. Water to be treated for ions is supplied to the desalting chamber, and water of appropriate water quality is passed through the concentration chamber and the polar chamber, respectively. FIG. 1 shows an example in which RO treated water is supplied to all of the desalting chamber, the concentration chamber, and the polar chamber. When water is passed through the desalting chamber and the concentrating chamber in this way, cations and anions in the water to be treated are attracted to the cathode side and the anode side, respectively, but the anion exchange membrane and the cation exchange membrane are each anion. Alternatively, in order to selectively permeate only cations, cations (Ca ²⁺ , Na ⁺ , Mg ²⁺ , H ^+, etc.) in the water to be treated pass through the cation exchange membrane C to the cathode side concentrating chamber and anions (Cl ⁻ , SO ₄ ²⁻ , HSiO ₃ ²⁻ , HCO ₃ ⁻ , OH ^−, etc.) move to the concentration chamber on the anode side through the anion exchange membrane A. On the other hand, the movement of the anion from the cathode side concentration chamber to the desalting chamber and the movement of the cation from the anode side concentration chamber to the desalting chamber are blocked by the different sign ion blocking property of the ion exchange membrane. As a result, desalted water having a reduced ion concentration is obtained from the desalting chamber, and concentrated water having an increased ion concentration is obtained from the concentrating chamber.

  According to such an electrical desalting apparatus, pure water with higher purity can be obtained as desalted water by using water with less impurities equivalent to, for example, RO (reverse osmosis membrane) treated water as the treated water. Recently, more advanced ultrapure water, such as ultrapure water for semiconductor manufacturing, has been required. Therefore, in a recent electric desalination apparatus, a desalination chamber and / or a concentration chamber and / or a polar chamber are mixed with cation exchange resin beads and anion exchange resin beads as an ion exchanger, and these are filled. A method of promoting the movement of ions in the room is known. Furthermore, as an ion exchanger, a cation exchange fiber material (nonwoven fabric, etc.) is placed on the cation exchange membrane side and an anion exchange fiber material on the anion exchange membrane side in the desalting chamber. A method of filling a spacer or an ion conductive spacer imparted with ion conductivity between them is also proposed (see, for example, JP-A-5-64726 and International Publication W099 / 48820 pamphlet).

  As described above, when water to be treated is passed through a desalination chamber filled with an ion exchanger, the salt to be removed is caused by an ion exchange reaction between the salt to be removed in the water to be treated and the ion exchange group of the ion exchanger. The For example, when NaCl is used as the salt to be removed, a sulfonic acid group is used as the cation exchange group, and a quaternary ammonium salt is used as the anion exchange group, it can be explained as follows.

When the treated water in which the salt to be removed (NaCl) is dissolved comes into contact with the cation exchanger, the cation (Na ⁺ ) in the treated water is ion-exchanged by the cation exchange group and adsorbed on the solid phase (cation exchanger) to be removed. (Equation 1).

  The water to be treated from which a certain amount of cations has been removed by contacting with the cation exchanger is then contacted with the anion exchanger. At this time, the acid (HCl) produced by the ion exchange reaction (formula 1) by the cation exchange group is completely neutralized as shown in formula 2.

On the other hand, the salt to be removed in the water to be treated that has not reacted with the cation exchanger comes into contact with the anion exchanger, and as shown in Formula 3, the anion (Cl ⁻ ) is ion-exchanged by the anion exchange group, and the solid phase (anion It is adsorbed and removed by the exchanger.

  Next, the water to be treated comes into contact with the cation exchanger, and the alkali (NaOH) generated by the ion exchange reaction (Formula 3) by the anion exchange group is neutralized as shown in Formula 4.

  The above formulas 1 and 3 are equilibrium reactions, and therefore the salt to be removed contained in the water to be treated is not completely ion-exchanged and removed by one contact with the anion exchanger and the cation exchanger, It remains to some extent in the treated water. Therefore, in order to efficiently remove ions, it is necessary to repeatedly perform the reactions of the above formulas 1 to 4, and for that purpose, water to be treated is alternately exchanged into a cation exchanger and an anion exchanger as much as possible. It is important that the salt to be removed is moved to the solid phase by the reaction of Formula 1 to Formula 4 after contact with a number of times.

  In order for the ions to be removed in the water to be treated to cause an ion exchange reaction and a neutralization reaction as described above, the removal target ions move to the vicinity of the functional group and then undergo an ion exchange reaction. is necessary. In an electric desalination apparatus, the water to be treated is continuously supplied to the desalting chamber, and it is necessary to cause an ion exchange reaction and a neutralization reaction while passing through the desalting chamber in a short time. It is desirable that the ions to be removed be diffused in the vicinity of the functional group of the ion exchanger in a short time and the contact frequency between the functional group and the ion is kept high.

  In the electric desalting apparatus, the ions to be removed adsorbed on the solid phase (ion exchanger) by the ion exchange reaction and neutralization reaction of the above formulas 1 to 4 are passed from the desalting chamber to the concentrating chamber or It is necessary to move to the polar chamber. In this case, the ions to be removed adsorbed on the ion exchanger are not continuously desorbed in the liquid phase, but continuously on the solid phase (ion exchanger) between the desalting chamber and the concentration chamber. It is desirable to move to the ion exchange membrane. That is, in the desalination chamber, the cation exchanger in contact with the cation exchange membrane and the anion exchanger in contact with the anion exchange membrane are filled between the cation exchange membrane and the anion exchange membrane, respectively, forming a continuous phase. Is desirable.

  Further, in the electric desalination apparatus in which the ion exchanger is filled in the chamber as described above, the portion where the cation exchange group and the anion exchange group come into contact in the desalination chamber and / or the concentration chamber filled with the ion exchanger. Exists. In particular, at the site where the cation exchange group and the anion exchange group in the desalting chamber come into contact, dissociation of water under a rapid potential gradient (Equation 5):

And the ion exchanger in the desalting chamber is regenerated by H ⁺ ions and OH ⁻ ions generated by this dissociation (hydrolysis), thereby making it possible to obtain high-purity pure water. Therefore, for efficient desalting, it is desirable to increase the hydrolytic site, that is, the number of contact sites between the anion exchanger and the cation exchanger. Furthermore, the H ⁺ ions and OH ⁻ ions generated by the hydrolysis continuously regenerate the ion exchange groups of the adjacent cation exchanger and anion exchanger one after another. In such a structure, if the energization operation is continued, the functional group counter ions will be insufficient locally at the contact site between the cation exchanger and the anion exchanger, and water in the vicinity of the functional group will be compensated for. Dissociates, and H ⁺ ions and OH ⁻ ions can be continuously supplied to the cation exchange group and the anion exchange group. Further, not only water but also non-electrolytes such as alcohols can be adsorbed and removed by functional groups by being polarized and dissociated by a strong electric field to become anions and cations. Therefore, it is desirable that a large number of contact sites (hydrolysis field) between the anion exchanger and the cation exchanger exist in a particularly dispersed manner throughout the desalting chamber. It is desirable that the cation exchangers are arranged to form a continuous phase.

  Furthermore, in recent years, pure water with higher purity has been demanded, and it is desired that the concentration of the TOC (organic carbon) component contained in the treated water is low. The TOC component contained in the treated water obtained by the electric desalting treatment is endogenous, that is, derived from the elution component from the ion exchanger filled in the desalting apparatus, and exogenous, that is, in the treated water. Some are derived from the TOC included. Of these, the TOC component eluted from the ion exchanger is often an unreacted monomer attached to the ion exchanger during the synthesis of the ion exchanger or a polymer electrolyte that is not crosslinked. These gradually elute into the liquid phase by washing with water, but it is desirable to use an ion exchanger having a structure that can be washed in as short a time as possible. It is also desirable to eliminate the crosslinking reaction from the ion exchanger synthesis process and prevent the uncrosslinked polymer electrolyte from being mixed into the ion exchanger. On the other hand, the TOC component contained in the water to be treated can be removed by ionization under a strong potential gradient, similar to the water dissociation reaction between the cation exchange group and the anion exchange group. Therefore, it is desirable that the water to be treated containing the TOC component can be uniformly circulated through the contact site between the cation exchanger and the anion exchanger.

  Moreover, as treated water (pure water) obtained, it is further desired that the concentration of weak electrolytes such as silica components and carbonic acid is low. Also in these cases, it is effective to ionize the weak electrolyte under a strong potential gradient as in the dissociation reaction of water between the cation exchange group and the anion exchange group. Therefore, in this case as well, it is desirable that the water to be treated containing the weak electrolyte can be uniformly distributed at the contact portion between the cation exchanger and the anion exchanger.

The functions required for the electric desalting apparatus have been listed above. However, no electric desalting apparatus having a conventional configuration has been obtained that satisfies all of these requirements.
For example, in many conventional electric desalting apparatuses, anion exchange resin beads and cation exchange resin beads are mixed and filled in a desalting chamber. In this case, since the filling state of the resin is random and the flow of water in the room is also random, when viewed microscopically, the contact between the water to be treated and the ion exchanger is not necessarily an anion exchanger and a cation. It was not an alternating contact with the exchanger. In addition, the particle size of the ion exchange resin beads to be filled is usually about 500 μm in order to reduce the pressure loss, but most of the functional groups of the ion exchange resin beads are inside the beads. Since the ions to be removed are not easily diffused to the vicinity of the functional group, the contact frequency between the ions to be removed and the functional group is not so high. In addition, since the cation exchanger and the anion exchanger are packed randomly, the cation exchanger and the anion exchanger are less likely to form a continuous phase, and the ions to be removed continue in the solid phase from the desalting chamber to the concentration chamber. Therefore, the TOC component removal performance and the weak electrolyte removal performance are also low. Furthermore, ion exchange resin beads have a large amount of elution of TOC components, and in particular, TOC components eluted from the macropores and micropores have a problem that it is difficult to completely remove the resin beads even if they are washed with water for a long time.

  In addition, a conventional electric desalination apparatus has been proposed in which ion-exchange resin beads are packed in layers. In such a form, an anion exchange resin bead and a cation exchange resin bead are alternately filled in a desalting chamber with a plastic mesh screen or the like interposed as necessary, and the desalting chamber is partitioned. The anion exchange resin bead single bed and the cation exchange resin bead single bed are alternately formed in the divided compartments, and a block in which the ion exchange resin beads are bound with a binder is formed. There are those in which blocks of exchange resin beads are alternately filled. However, it is extremely difficult to orderly fill the desalting chamber with anion exchange resin beads and cation exchange resin beads while alternately forming layers. In addition, when a mesh screen or the like is interposed between the layers, or when the layers are alternately formed by dividing the desalting chamber with partitions, the site where the anion exchange group and the cation exchange group are in contact (hydrolysis generation field) This is limited to the contact surface between the ion exchange membrane and the ion exchanger filled in the chamber, and a large number of hydrolytic sites cannot be formed in the desalting chamber. Further, when the desalting chamber is divided by partitions, the number of resin layers that can be formed is limited to several to several tens from the ease of assembly of the chamber and the overall size of the apparatus. Further, as long as ion exchange resin beads are used, as described above, the contact frequency between the ion to be removed and the ion exchange group is not so high. Furthermore, when ion-exchange resin beads are bound with a binder, the flow path of water is limited by the binder, so the contact frequency between the ions to be removed and the ion-exchange group is significantly reduced. Also, the amount of TOC eluted is high as described above because ion-exchange resin beads are used. In particular, when a binder is used, the binder itself becomes an elution component, so the TOC concentration of treated water is higher. Get higher. Furthermore, as described above, since the contact portion between the anion exchange group and the cation exchange group is limited to the contact surface between the ion exchange membrane and the ion exchanger filled in the room, most of the water to be treated is here. The ionization of the TOC component and the weak electrolyte is difficult and therefore the removal performance is low.

  In order to eliminate the various problems associated with the use of the above ion exchange resin beads, ion exchange fiber materials in which ion exchange groups are introduced into the fiber material such as woven fabric and nonwoven fabric by a radiation graft polymerization method are removed. It has been proposed to use it as a filling material for a salt chamber (for example, the above-mentioned JP-A-5-64726). The ion exchange fiber material has a larger specific surface area than the ion exchange resin beads, and the ion exchange groups are not present in the micropores or macropores inside the beads unlike the ion exchange resin beads. Is disposed on the surface of the fiber. Therefore, ions to be removed in the water to be treated are easily transported along the flow (by convection) in the vicinity of the ion exchange group. Therefore, when the ion exchange fiber material is used, the contact frequency between the ion to be removed and the ion exchange group can be remarkably improved as compared with the case where ion exchange resin beads are used.

  However, since fiber materials such as woven fabrics and nonwoven fabrics are generally not very water-permeable, filling a fiber material into a conventional thin desalting cell results in a pressure loss that is too large to obtain a sufficient treatment flow rate. It was considered impossible.

Therefore, in the desalination chamber, a cation exchange fiber material such as a nonwoven fabric is disposed on the cation exchange membrane side, and an anion exchange fiber material is disposed on the anion exchange membrane side so as to face each other. There has been proposed an electric desalination apparatus filled with a net-like spacer or an ion conductive spacer imparted with ion conductivity (for example, the above-mentioned International Publication W099 / 48820 pamphlet). In the case of the apparatus having such a configuration, the water to be treated becomes a turbulent flow in the oblique mesh spacer or the ion conductive spacer, and comes into contact with the cation exchange fiber material and the anion exchange fiber material. Accordingly, the water to be treated comes into contact with the cation exchange fiber material and the anion exchange fiber material to some extent alternately, but it cannot be said that the alternate contact is performed sufficiently efficiently. In addition, although a fiber material having a large surface area and a large number of available ion exchange groups is used, most of the water to be treated flows through the spacer part due to the difference in water permeability between the fiber material and the spacer. There is very little flow through the nonwoven fabric. For this reason, the contact frequency of the ion to be removed and the ion exchange group is low.
Japanese Patent Laid-Open No. 5-64726 International publication W099 / 48820 pamphlet

  As a result of considering the functions required for the electric desalination apparatus by systematic construction as described above, the present inventors have determined that the water to be treated is treated with a cation exchanger and a cation exchanger in order to enhance desalting performance and TOC removal performance. Contact with anion exchanger in multiple stages alternately, increase the contact frequency between ions to be removed and ion exchange groups in treated water, anion exchange between anion exchange membrane and cation exchange membrane in desalination chamber The continuous phase of each of the cation exchanger and the cation exchanger is formed, and a large number of contact portions between the cation exchange groups and the anion exchange groups are formed throughout the desalting chamber, and the treated water is sufficiently distributed there. I thought it was important to make it. And as a result of intensive studies to provide an electric desalination apparatus that satisfies all these conditions, the desalting performance and TOC removal performance of the electric desalination apparatus are greatly improved by selecting appropriate materials and improving the filling method. Successfully improved.

Preferred embodiment

Hereinafter, various specific embodiments of the present invention will be described with reference to the drawings.
FIG. 2 is a conceptual diagram illustrating a configuration example of an electrical desalination apparatus according to one embodiment of the present invention. An anion exchange membrane (A) and a cation exchange membrane (C) are disposed between the cathode (-) and the anode (+) to define a concentration chamber and a desalting chamber. A chamber in contact with both electrodes is called a polar chamber. As will be apparent to those skilled in the art, the bipolar chamber functions as either a desalting chamber or a concentrating chamber. In general, the outermost concentration chamber is often provided as a polar chamber. For example, in the apparatus shown in FIG. 2, when electrodes are disposed in the concentration chambers on both sides of the central desalting chamber, that is, between the anode and the cathode, the concentration chamber-desalination chamber-concentration chamber 3 When only chambers are formed, the concentration chambers on both sides also function as polar chambers. Accordingly, those skilled in the art will appreciate that such an apparatus is also included within the scope of the “electric desalination apparatus having a desalination chamber, a concentration chamber, and an electrode chamber” as defined in the claims of the present application. it is obvious.

  In the desalination chamber defined by the anion exchange membrane on the anode side and the cation exchange membrane on the cathode side, a fiber material having a cation exchange function (referred to as a cation exchange fiber material) and a fiber material having an anion exchange function (anion exchange fiber material) And a plurality of layers are stacked so as to intersect the flow direction (water flow direction) of the water to be treated. That is, in the conventional electric desalination apparatus, when filling a desalting chamber or a concentration chamber with a sheet material such as an ion exchange fiber material or an ion conducting spacer, as shown in FIG. In the electric desalination apparatus according to the present invention, the ion-exchange fiber material is filled in the desalting chamber. And filling in the direction crossing the flow direction (water flow direction) of the water to be treated and crossing the ion exchange membrane constituting the chamber. It is preferable that the ion exchange fiber material is laminated in the above-described direction, and as shown in FIG. 2, the layer of the cation exchange fiber material and the layer of the anion exchange fiber material are alternately laminated. Further preferred.

  In the electric desalination apparatus having such a configuration, the anion exchange fiber material and the cation exchange fiber material are laminated and disposed so as to intersect the flow direction of the water to be treated. It passes through and flows from one surface to the other. Therefore, since the water to be treated can be sufficiently supplied to the entire ion exchange fiber material having many usable ion exchange groups, these ion exchange groups can be effectively utilized. This greatly increases the number of ion exchange groups available per length of desalting chamber (the direction in which the water to be treated flows), so the length of the desalting chamber is reduced compared to the conventional one. be able to. The ion exchange fiber material has the above-mentioned pressure loss problem. Thus, in the electric desalination apparatus according to the present invention, the length along the flow direction of the water to be treated in the desalination chamber is set to the conventional value. Since it can be made much shorter than that, the increase in the pressure loss of the water to be treated is not a problem in practice.

  In addition, according to the present invention, the contact portion between the anion exchanger and the cation exchanger in the desalting chamber, that is, the hydrolysis generation field is formed over the entire cross section of the water stream to be treated. A large amount of water to be treated can be supplied to promote regeneration of the ion exchanger by hydrolysis and decomposition of weak electrolytes such as TOC and silica. In order to achieve such an object, it is preferable that the anion exchange fiber material and the cation exchange fiber material filled in the desalting chamber are in contact with each other.

  In the present invention, it is only necessary that at least one of the anion exchange fiber material and the cation exchange fiber material is disposed so as to intersect the flow direction of the water to be treated. For example, the effect of the present invention can also be obtained by arranging a plurality of anion exchange fiber materials so as to intersect the flow direction of the water to be treated and filling cation exchange resin beads between the layers of the anion exchange fiber material. Such forms are also encompassed by the present invention. Alternatively, in the desalination chamber, a portion in which a plurality of anion exchange fiber materials are arranged so as to cross the flow direction of the water to be treated and the cation exchange resin beads are filled between the layers of the anion exchange fiber material; In addition, a plurality of cation exchange fiber materials are arranged so as to cross the flow direction of the water to be treated, and there are both portions filled with anion exchange resin beads and the like between the cation exchange fiber material layers. It may be configured.

  In the present invention, in the desalting chamber, the anion exchange fiber material that is laminated and disposed so as to intersect the flow direction of the water to be treated, and the anion exchange membrane that defines the desalting chamber, or the cations that are laminated It is preferable that at least one of the exchange fiber material and the cation exchange membrane that defines the desalting chamber is in contact. That is, in the configuration shown in FIG. 2, the anion exchange fiber material arranged in the desalting chamber and the anion exchange membrane (A) are in contact with each other, or the cation exchange fiber material arranged in the desalting chamber and the cation exchange. It is preferred that the membrane (C) is in contact or both are in contact. With such a configuration, the ions to be removed in the water to be treated adsorbed by ion exchange by the ion exchange fiber material travel along the ion exchange fiber material to the ion exchange membrane and pass through the ion exchange membrane. Move to the adjacent concentration chamber. Therefore, the ions to be removed adsorbed on the ion exchanger can continuously move to the ion exchange membrane on the solid phase (ion exchanger) without being desorbed in the liquid phase.

In the present invention, it is preferable that at least one of the anion exchange fiber material and the cation exchange fiber material disposed in the desalting chamber is disposed so as to contact both the anion exchange membrane and the cation exchange membrane. . In the configuration shown in FIG. 2, both the anion exchange fiber material and the cation exchange fiber material are in contact with both the anion exchange membrane and the cation exchange membrane that define the desalination chamber. With such a configuration, for example, the contact point between the anion exchange fiber material and the cation exchange membrane (C) functions as a hydrolytic field. The OH ^- ions generated by hydrolysis in this part move toward the anode while successively regenerating the anion exchange groups of the anion exchange fiber material. Therefore, OH 2 ⁻ ions generated by hydrolysis are regenerated by moving from end to end of the desalting chamber, which is extremely efficient. The same applies to H ⁺ ions generated at the contact point between the anion exchange membrane (A) and the cation exchange fiber material.

  Furthermore, in the present invention, as shown in FIG. 3, an anion exchange fiber material is disposed along the surface of the anion exchange membrane in the desalting chamber and / or the cation exchange fiber material along the surface of the cation exchange membrane. Is preferably arranged. When the layer of the ion exchange fiber material is not disposed along the surface of such an ion exchange membrane, the ion exchange fiber material that is laminated and disposed so as to intersect the flow direction of the water to be treated and the flow direction of the water to be treated The contact between the ion exchange membranes arranged in the same way is made at the end of the ion exchange fiber material, so that the contact does not become dense, which may cause a problem of low ion conductivity. Such a problem may lead to an increase in operating voltage. However, according to the embodiment shown in FIG. 3, such a problem can be solved.

  In the present invention, it is preferable that the anion exchange fiber material layers and the cation exchange fiber material layers arranged so as to cross the flow direction of the water to be treated are alternately and as many as possible in the desalting chamber. . If a large number of anion exchange fiber material layers and cation exchange fiber material layers are alternately arranged, the above-mentioned condition that “the treated water is alternately brought into contact with the cation exchanger and the anion exchanger as many times as possible” is satisfied. It is possible to remove ions to be removed from the water to be treated by ion exchange more completely. In addition, if a large number of cation exchanger layers and anion exchanger layers are alternately laminated, a large number of sites where the anion exchanger and the cation exchanger come into contact, that is, a site where water hydrolysis occurs, throughout the desalting chamber. Since it can be formed, the regeneration of the ion exchanger and the decomposition of the TOC component and silica are performed very efficiently.

  In the electric desalting apparatus according to the present invention, the configuration of the concentration chamber and the electrode chamber is not particularly limited, but it is preferable that the concentration chamber and / or the electrode chamber are also filled with an ion exchanger. As the ion exchanger filled in the concentration chamber or the electrode chamber, any material proposed to be used in an electric desalting apparatus can be used. For example, it can be used as an ion exchanger for filling the electrode chamber with an ion exchange fiber material or the like having the same ion exchange function as that for filling the desalting chamber. Further, the ion disclosed in Patent Document 2 can be used. An ion conductive spacer in the form of a slanted net or the like imparted with conductivity can be used as an ion exchanger that fills the concentration chamber or the electrode chamber. In addition, the concentrating chamber and the electrode chamber can be filled with a spacer in the form of an oblique network that is not imparted with ion conductivity.

  Further, the structure of the electric desalting apparatus according to the present invention includes the following structure. i) In an electric desalination apparatus in which a plurality of desalting chambers and concentration chambers are alternately arranged, a desalting chamber having the basic structure of the present invention is provided. ii) In the desalting chamber, a layer of anion exchange fiber material and / or a layer of cation exchange fiber material is laminated and arranged in a direction crossing the flow direction of the water to be treated, and other ion exchanges between these layers. A structure in which at least one layer composed of the body is inserted. iii) A layer of anion exchange fiber material and / or a layer of cation exchange fiber material is laminated in the desalting chamber, at least one layer of which is an anion exchange fiber material or a fiber material having a cation exchange function and other ion exchangers. Consists of a composite with.

In addition, in the contact portion between the cation exchanger and the anion exchanger in the desalting chamber of the electric desalination apparatus, a bond between the cation exchange group and the anion exchange group occurs. The exchanger becomes more firmly bonded. As in the electric desalination apparatus according to the present invention, the ion exchanger is disposed in the desalting chamber so as to intersect with the flow direction of the water to be treated, that is, the ion exchange is performed so as to intersect with the ion exchange membrane defining the desalting chamber. In the case where the body is arranged, in order to prevent the water to be treated from preferentially flowing between the ion exchange membrane and the filled ion exchanger, the contact portion between the ion exchange membrane and the ion exchanger Need to be more firmly attached. Therefore, in the electric desalination apparatus according to the present invention, in the initial stage of operation, the energization operation is performed at a low flow rate (for example, SV <100 h ⁻¹ ), and the cation exchange membrane, anion exchanger, and anion exchange in the desalination chamber are performed. It is desirable to perform normal operation by increasing the flow rate after forming the bond between the membrane and the cation exchanger by energization operation. Furthermore, in order to maintain the bond between the ion exchange membrane and the ion exchanger in the desalting chamber over a long period of time, the pressure in each concentrating chamber and the pressure in each desalting chamber are maintained at the same level, and ion exchange is performed. It is further desirable to prevent the membrane and ion exchanger from peeling off.

  As the ion exchange fiber material that can be used in the electric desalination apparatus according to the present invention, a material obtained by introducing an ion exchange group into a polymer fiber base material by a graft polymerization method is preferably used. The grafted substrate made of polymer fibers may be a polyolefin-based polymer, for example, a kind of single fiber such as polyethylene or polypropylene, or a composite fiber composed of a polymer having a different core and sheath. It may be. Examples of the composite fibers that can be used include core-sheath composite fibers having a polyolefin-based polymer, for example, polyethylene as a sheath component, and polymers other than those used as the sheath component, for example, polypropylene as a core component. . A material obtained by introducing an ion exchange group into such a composite fiber material using a radiation graft polymerization method is preferable as the ion exchange fiber material used in the present invention because it has excellent ion exchange capability and can be produced with a uniform thickness. Examples of the form of the ion exchange fiber material include woven fabric and nonwoven fabric.

  Further, as an ion conductive spacer that can be used in the electric desalination apparatus according to the present invention, polyolefin polymer resin, for example, a polyethylene oblique network (net) conventionally used in an electrodialysis tank It is preferable to use a base material having an ion exchange function using a radiation graft method because it has excellent ion conductivity and dispersibility of water to be treated.

  The ion exchange fiber material and ion conductive spacer used in the electric desalination apparatus according to the present invention are preferably manufactured using a radiation graft polymerization method. The radiation graft polymerization method is a technique in which a monomer is introduced into a substrate by irradiating a polymer substrate with radiation to form radicals and reacting the monomer with this.

  Examples of radiation that can be used in the radiation graft polymerization method include α rays, β rays, gamma rays, electron beams, ultraviolet rays, and the like. In the present invention, gamma rays and electron beams are preferably used. The radiation graft polymerization method includes pre-irradiation graft polymerization method in which a graft substrate is irradiated with radiation in advance and then brought into contact with the graft monomer and reacted, and simultaneous irradiation graft polymerization method in which radiation is irradiated in the presence of the substrate and the monomer. However, in the present invention, any method can be used. In addition, by the contact method of the monomer and the base material, a liquid phase graft polymerization method for performing polymerization while the base material is immersed in the monomer solution, a vapor phase graft polymerization method for performing the polymerization by bringing the base material into contact with the vapor of the monomer, Examples of the method include an impregnation gas phase graft polymerization method in which the base material is immersed in the monomer solution and then taken out from the monomer solution and reacted in the gas phase, and any method can be used in the present invention.

  As an ion exchange group introduce | transduced into fiber base materials, such as a nonwoven fabric, and a spacer base material, various cation exchange groups or anion exchange groups can be used without being specifically limited. For example, as the cation exchange group, a strong acid cation exchange group such as a sulfonic acid group, a neutral acid cation exchange group such as a phosphate group, a weak acid cation exchange group such as a carboxyl group, and the anion exchange group include primary to Weakly basic anion exchange groups such as tertiary amino groups, strong basic anion exchange groups such as quaternary ammonium groups can be used, or ion exchange having both of the above cation exchange groups and anion exchange groups The body can also be used.

  These various ion exchange groups are graft-polymerized using monomers having these ion-exchange groups, preferably radiation graft polymerization, or using polymerizable monomers having groups convertible to these ion-exchange groups. By converting the group into an ion exchange group after graft polymerization, it can be introduced into the fiber substrate or spacer substrate. Examples of monomers having ion exchange groups that can be used for this purpose include acrylic acid (AAc), methacrylic acid, sodium styrenesulfonate (SSS), sodium methallylsulfonate, sodium allylsulfonate, sodium vinylsulfonate, vinyl Examples thereof include benzyltrimethylammonium chloride (VBTAC), diethylaminoethyl methacrylate, dimethylaminopropylacrylamide and the like. For example, by performing radiation graft polymerization using sodium styrenesulfonate as a monomer, a sulfonic acid group that is a strongly acidic cation exchange group can be directly introduced into the substrate, and vinylbenzyltrimethylammonium chloride is used as a monomer. The quaternary ammonium group, which is a strongly basic anion exchange group, can be directly introduced into the base material by carrying out radiation graft polymerization. Examples of the monomer having a group that can be converted into an ion exchange group include acrylonitrile, acrolein, vinylpyridine, styrene, chloromethylstyrene, and glycidyl methacrylate (GMA). For example, glycidyl methacrylate is introduced into a substrate by radiation graft polymerization, and then a sulfonic acid group, which is a strongly acidic cation exchange group, is introduced into the substrate by reacting with a sulfonating agent such as sodium sulfite, or chloro After graft polymerization of methylstyrene, a quaternary ammonium group that is a strongly basic anion exchange group can be introduced into the substrate by immersing the substrate in an aqueous trimethylamine solution to perform quaternary ammonium formation.

  2 and 3, the sheet-type ion exchange fiber material is laminated in a direction crossing the flow direction of the water to be treated in the desalting chamber, that is, horizontally, and is stacked horizontally. In addition, the electrical desalination apparatus according to the present invention can be configured by a filling method of an ion exchange fiber material as described below.

  First, as shown in FIG. 4, a long sheet-like anion exchange fiber material and a cation exchange fiber material are overlapped and folded according to the dimensions of the desalting chamber to form a pleated ion exchange fiber material structure. The pleated structure is filled in the desalting chamber so that the surface of the pleats intersects the direction of water flow and both cross sections of the structure are in contact with the cation exchange membrane and the anion exchange membrane that define the desalination chamber. By doing so, the electric desalination apparatus according to the present invention can be configured. In addition, as shown in FIG. 5, a long sheet-like anion exchange fiber material and a cation exchange fiber material are overlapped and wound into a roll, and this roll is divided into a cation exchange membrane in which both cross sections define a desalination chamber, The electric desalting apparatus according to the present invention can also be configured by filling one or more in the desalting chamber so as to be in contact with the anion exchange membrane. 4 and 5, the anion exchange fiber material layer and the cation exchange fiber material layer are laminated and arranged so as to intersect the flow direction of the water to be treated. It is included in the scope of the electric desalination apparatus of the invention. Also in these forms, as shown in FIG. 3, the anion exchange fiber material is arranged along the surface of the anion exchange membrane that defines the desalting chamber, and / or the cation is exchanged along the surface of the cation exchange membrane. By arranging the exchange fiber material, the contact between the ion exchanger filled in the desalting chamber and the ion exchange membrane defining the desalting chamber can be made stronger.

  Examples of the ion exchange membrane used to constitute the electric desalination apparatus according to the present invention include NEOSEPTA CMX (Tokuyama) as the cation exchange membrane, and NEOSEPTA AMX (Tokuyama) as the anion exchange membrane. Etc. can be used.

  Due to the configuration as described above, according to the electric desalination apparatus according to the present invention, the following effects can be obtained, and the desalination efficiency of the electric desalination apparatus can be greatly improved. The apparatus can be miniaturized. It becomes possible to make the water to be treated contact the cation exchanger and the anion exchanger completely and alternately in multiple stages.

  1. The fiber material layer with ion exchange function is composed of fibers and has a small fiber diameter, so the solid phase migration diffusion distance of ions is short, the surface area is large, and the contact frequency between ions to be removed and functional groups is high, so ion exchange The time until the reaction reaches an equilibrium state is short, and the neutralization reaction is likely to be completed.

2. The fiber material layer having a cation exchange function and the fiber material layer having an anion exchange function are in close contact with the cation exchange membrane and the anion exchange membrane, respectively. The ions to be removed adsorbed on the solid phase by ion exchange and the H ⁺ ions and OH ⁻ ions generated in the hydrolysis easily move in the solid phase and are not desorbed in the aqueous phase. It is carried to the concentration chamber.

  3. As a contact portion between the cation exchanger and the anion exchanger, a contact portion between the cation exchange membrane and the anion exchange fiber material layer, a contact portion between the anion exchange membrane and the cation exchange fiber material layer, and a cation exchange fiber material layer and the anion exchange fiber A contact portion with the material layer is provided. In addition, when the ion exchange fiber material is alternately packed in multiple layers, most of the hydrolysis is considered to occur at the contact portion between the cation exchange fiber material layer and the anion exchange fiber material layer. Therefore, a large amount of the water to be treated flows in the place where the hydrolysis occurs, and the ionization of the TOC component and the weak electrolyte is promoted in the hydrolysis field, and the removal rate of the TOC component and the weak electrolyte component is improved.

Based on the above principle, according to the electric desalination apparatus according to the present invention, for example, when water equivalent to RO treated water is supplied as treated water at 10 Lh ⁻¹ , SV (space velocity: treated water supply speed / It is possible to stably obtain treated water having a total desalting chamber volume) = 200 h ⁻¹ , an operating current of 0.4 A, a specific resistance of about 18.0 MΩcm, a TOC concentration of 10 ppb or less, and a silica concentration of 30 ppb or less.

  By adopting the configuration of the present invention in which at least one of the layer of the anion exchange fiber material and the layer of the cation exchange fiber material intersects the flow direction of the water to be treated in the desalination chamber, as described above, Since the desalination efficiency per volume of the desalination chamber can be greatly improved, the size of the electric desalination apparatus can be significantly reduced as compared with the conventional one.

  However, when the electric desalination apparatus reduced in size as described above is operated for a long time by the subsequent studies of the present inventors, the water to be treated contains a large amount of calcium and carbonate, that is, water with high hardness. In some cases, it has been found that there is a strong tendency for the operating voltage to increase over time. This is because calcium ions and carbonate ions in the water to be treated are introduced into the concentration chamber from the adjacent desalting chamber and concentrated in the concentration chamber, so that calcium carbonate is generated and precipitated as crystals, and this is used as an insulator. This is considered to be because the operating voltage rises in order to hinder the flow of electricity. This phenomenon has also been confirmed in the conventional electric desalination equipment, but because the equipment is large, the electrode area is large and the current density is low, so that calcium carbonate is formed thin overall. Therefore, it is considered that it was less likely to cause serious problems due to precipitation of calcium carbonate crystals. However, it is considered that this problem may become apparent as the desalination apparatus is greatly reduced in size according to the present invention.

  Considering the phenomenon of precipitation of calcium carbonate crystals in the concentration chamber, first, calcium carbonate is generated at the anion exchanger / cation exchanger contact interface in the concentration chamber. Since the produced calcium carbonate has low solubility, it precipitates as crystals, and the produced crystal particles act as seed nuclei, and the crystal precipitation proceeds. The present inventor pays attention to such a calcium carbonate crystal precipitation mechanism, and the calcium carbonate is generated by dispersing the contact interface of the anion exchanger / cation exchanger, where calcium carbonate is generated, throughout the concentration chamber. Even so, attention was paid to the fact that the desalting operation can be performed stably without precipitation as crystals. Then, by adopting the configuration of the present invention in the desalination chamber described above also in the concentration chamber, it was conceived that the contact interface of the anion exchanger / cation exchanger in the concentration chamber can be dispersed throughout the chamber, The second preferred embodiment of the present invention has been completed.

  That is, in the second preferred embodiment of the present invention, at least one of the anion exchange fiber material layer and the cation exchange fiber material layer is laminated and disposed in the water passing direction in the concentration chamber of the electric desalination apparatus. It is characterized by this.

  In the second aspect of the present invention, the ion exchange fiber material filling method and water flow method into the concentration chamber are shown in FIGS. 2 to 5 with respect to the ion exchange fiber material filling method and water flow method into the desalting chamber. Various forms described above with reference to the drawings can be employed.

Furthermore, further research by the present inventor has shown that the operation voltage of the desalting operation can be further stabilized in the electrode chamber by arranging the ion-exchange fiber materials so as to cross the water direction. It was. In an electrode chamber, particularly a cathode chamber, it is known that the voltage applied to both ends of the chamber increases with the passage of time for the desalting operation. As a result of the study by the present inventors, this phenomenon is caused by electrolysis of water on the electrode surface, which generates OH ⁻ ions, which are combined with calcium ions in the water flow to generate calcium hydroxide. It was concluded that the electrical resistance was increased by depositing and forming an insulator film. Therefore, in the electrode chamber, particularly in the cathode chamber, the contact area between the electrode and the water flow is remarkably increased by stacking and arranging the ion exchange fiber materials in the direction crossing the water flow direction, and the generated hydroxylation. Since calcium is suppressed from being localized and dispersed throughout the polar chamber, precipitation of calcium hydroxide crystals in the polar chamber can be suppressed, and as a result, an increase in voltage difference in the polar chamber can be suppressed. be able to. In addition, it is considered that the voltage applied to both ends of the cathode chamber also occurs due to the following causes. When filling the cathode chamber with an ion exchanger, an anion exchanger is usually used. Anion exchange groups such as quaternary ammonium groups (R—N ⁺ (CH ₃ ) ₃ ) are positively charged and are attracted to the electrode (cathode). At the electrode, usually water reduction reaction:

That is, water electrolysis occurs, but at the same time, the quaternary ammonium group is considered to be reduced.

  When the quaternary ammonium group is reduced, it loses the ion exchange function and becomes an insulator, so that the voltage applied to both ends of the polar chamber increases. In the conventional electric desalination apparatus, when the electrode chamber is filled with an ion exchanger, an ion conductive spacer is used. Therefore, the electrode and the ion exchanger are in contact with each other at a point, and the above-mentioned anion It is considered that the increase in the voltage applied to both ends of the polar chamber was conspicuous because the electrical flow was hindered by the insulation of the exchange group. However, according to the third aspect of the present invention, the negative electrode and the anion exchanger in the negative electrode chamber are particularly arranged by laminating and arranging the anion exchange fiber material in the cathode chamber in a direction intersecting the water direction. If the contact area has increased dramatically, it will come in contact with the surface, so that the insulation of the anion exchange group generated in a part of it does not affect the voltage rise across the polar chamber, As a result, an increase in voltage applied to both ends of the polar chamber can be suppressed. Accordingly, a further preferred third aspect of the present invention is that at least one of the anion exchange fiber material layer and the cation exchange fiber material layer is laminated in the water passage direction in the electrode chamber of the electric desalination apparatus. It is characterized by doing. In the third aspect of the present invention, it is particularly preferable that the anion exchange fiber material is laminated in the cathode chamber so as to intersect the water direction.

  Note that, in the third aspect of the present invention, it is particularly preferable that the ion exchange fiber material is laminated in the cathode direction so as to cross the water direction in the cathode chamber, and the cation exchange fiber material is laminated in the water direction so as to be laminated. More preferably. The other ion exchange fiber material filling method and water flow method adopt the various forms described above with reference to FIGS. 2 to 5 with respect to the ion exchange fiber material filling method and water flow method to the desalination chamber. can do. However, in the case of the cathode chamber, the chamber is defined by the cathode, usually an anion exchange membrane, and the anion exchange fiber material laminated in the cathode chamber, and the anion exchange membrane and the negative electrode that define the chamber The anion exchange fiber material laminated in the cathode chamber is arranged so as to contact both the anion exchange membrane and the negative electrode that define the chamber. Further, in the cathode chamber, an anion exchange fiber material can be disposed along the surface of the anion exchange membrane and / or the negative electrode that defines the chamber.

  The features of the various aspects of the present invention described above may be combined with each other or may be employed independently. That is, in the electric desalination apparatus according to the present invention, the chamber in which the ion-exchange fiber material is laminated and disposed so as to cross the water direction may be any one of the desalting chamber, the concentrating chamber, and the polar chamber, or The desalting chamber and the concentrating chamber, or the desalting chamber and the polar chamber, or the concentrating chamber and the polar chamber, or all of the desalting chamber, the concentrating chamber, and the polar chamber may be used. Further, as already described above, the ion-exchange fiber material can be laminated and disposed so as to intersect the water direction in one of the desalting chamber, the concentrating chamber, or the polar chamber.

  In addition, although said description demonstrated the aspect which laminates | stacks and arrange | positions an ion exchange fiber material in the flow direction of to-be-processed water in at least one chamber of a desalination chamber and a concentration chamber, compared with an ion exchange fiber material. In other words, any ion-exchange fiber material can be used instead of the ion-exchange fiber material as long as it has an equivalent amount of usable ion-exchange groups, has an equivalent amount of water permeability, and is a water-permeable porous material imparted with ion exchange properties. And can be arranged in a desalting chamber, and the effect of the present invention can be achieved by such a configuration. That is, another embodiment of the present invention is an electric desalination apparatus having a desalination chamber and a concentration chamber partitioned by a plurality of ion exchange membranes between a cathode and an anode, The present invention relates to an electrical desalting apparatus characterized in that, in at least one chamber, a water-permeable porous material layer provided with an ion exchange function is laminated and disposed so as to intersect with a flow direction of water to be treated.

  Examples of the water-permeable porous material that can be used in this aspect of the present invention include a porous substrate having continuous pores. “Porous substrate having communicating pores” means a general structure having pores continuously connected through the inside from one side of the substrate to the other side of the opposite side, for example, An open cell foam made of olefinic synthetic resin such as polyethylene and polypropylene, a natural open cell foam such as sponge, a flat weave in which fibers are woven in the vertical and horizontal directions, and a tertiary in which fibers are also woven in the thickness direction. Including original woven fabrics. Among these, polyolefin-based open-cell foams such as polyethylene-based porous bodies and polypropylene-based porous bodies can be preferably used, and three-dimensional woven fabrics are polyolefins in which polyethylene fibers, polypropylene fibers, etc. are woven three-dimensionally. A three-dimensional woven fabric can be preferably used. A material obtained by introducing an ion exchange group into these materials can be stacked in the desalting chamber in a direction crossing the flow direction.

As a porous substrate having continuous pores that can be used for this purpose, porosity: 93 to 96%, average pore diameter: 0.6 to 2.6 mm, specific surface area: 21000 to 38000 m ² / m ³ , especially Preferably it has about 30000 m ² / m ³ . Moreover, it needs to function as a base material which introduce | transduces an ion exchange group, and it is preferable to consist of polyolefin polymer, for example, polyethylene, a polypropylene, and these composites. Specifically, a polyethylene porous body (manufactured by Sekisui Chemical Co., Ltd.) having a porosity of 93 to 96%, an average pore diameter of 0.6 to 2.6 mm, and a specific surface area of about 30000 m ² / m ³ is particularly preferable. Can be used. In the present invention, by using an ion exchanger obtained by introducing an ion exchange group into a porous base material having such communicating pores, this is laminated and disposed so as to intersect the flow direction of the water to be treated. The liquid to be treated can be sufficiently brought into contact with the ion exchanger without passing through the ion exchanger without obstructing the flow of the water to be treated and maintaining the inflow pressure of the liquid to be treated at a high level.

  The introduction of ion exchange groups into the water-permeable porous material as described above can be performed by using the radiation graft polymerization method described above. In the case of anion exchanger, the ion exchange group is introduced with a neutral salt decomposition capacity of 2.8 to 3.3 meq / g, and with a cation exchanger of neutral salt decomposition capacity of 2.7 to 3.0 meq. It is preferable to carry out so that it becomes / g. If the neutral salt decomposition capacity of the ion exchanger is in the above range, there are many ion exchange groups that can come into contact with ions in the water to be treated, and a good ion exchange function can be achieved.

  Regarding the water-permeable porous material provided with the ion exchange function described above, the chamber in which it is disposed may be any one of a desalting chamber, a concentrating chamber, and a polar chamber, or a desalting chamber and a concentrating chamber. Alternatively, the desalting chamber and the polar chamber, or the concentrating chamber and the polar chamber, or all of the desalting chamber, the concentrating chamber, and the polar chamber may be used. Further, as already described above, a water-permeable porous material provided with an ion exchange function may be disposed in a part of the desalting chamber, a part of the concentration chamber, or one of the polar chambers.

Various aspects of the present invention are as follows.
1. An electrical desalination apparatus having a desalting chamber, a concentrating chamber, and an electrode chamber partitioned between a cathode and an anode by a plurality of ion exchange membranes, wherein the desalting chamber, the concentrating chamber, and the electrode chamber are at least one chamber In addition, at least one of the layer of anion exchange fiber material and the layer of cation exchange fiber material is laminated | stacked and arrange | positioned so that a water flow direction may cross | intersect.

  2. In at least one of the desalting chamber and the concentrating chamber, the anion exchange fiber material stacked in the chamber and the anion exchange membrane defining the chamber are arranged in contact with each other and / or the chamber 2. The electric desalination apparatus according to claim 1, wherein the cation exchange fiber material laminated on the cation exchange membrane and the cation exchange membrane defining the chamber are in contact with each other.

  3. In at least one of the desalting chamber and the concentration chamber, one or both of the anion exchange fiber material stacked in the chamber and the cation exchange fiber material stacked in the chamber define the chamber. The electrical desalting apparatus according to claim 1, which is disposed so as to be in contact with both the anion exchange membrane and the cation exchange membrane.

  4). In at least one of the desalting chamber and the concentration chamber, the anion exchange fiber material is disposed along the surface of the anion exchange membrane and / or the cation exchange fiber material is disposed along the surface of the cation exchange membrane. The electric desalination apparatus according to the above item 1.

  5. In the first item, the layers of the anion exchange fiber material and the layer of the cation exchange fiber material are alternately laminated so as to cross the water flow direction in at least one of the desalting chamber and the concentration chamber. ~ Electrical desalination apparatus according to any one of items 4 to 4.

6). The anion exchange fiber material and the cation exchange fiber material are electrical desalination apparatuses according to any one of Items 1 to 5 which are woven fabrics or nonwoven fabric materials.
7). At least one of an anion exchange fiber material and a cation exchange fiber material layer introduces an ion exchange group into a substrate using a radiation graft polymerization method. Type desalination equipment.

8). The electric desalination apparatus according to any one of the first to seventh aspects, wherein the anion exchange fiber material or the cation exchange fiber material is disposed in at least a part of the desalting chamber.
9. The electric desalination apparatus according to any one of the first to seventh aspects, wherein the anion exchange fiber material or the cation exchange fiber material is disposed in at least a part of the concentration chamber.

10. The electric desalination apparatus according to any one of the first to ninth aspects, wherein the anion exchange fiber material or the cation exchange fiber material is disposed in at least one of the electrode chambers.
11. The electrical desalination according to any one of the above items 1 to 7, wherein the anion exchange fiber material or the cation exchange fiber material is disposed in at least a part of the desalting chamber and at least a part of the concentration chamber. apparatus.

12 12. The electric desalination apparatus according to item 11, wherein the anion exchange fiber material or the cation exchange fiber material is disposed in at least one of the electrode chambers.
13. 13. The electric desalination apparatus according to item 10 or 12 above, wherein the layer of the anion exchange fiber material is disposed in the cathode chamber.

  14 14. The electrical type according to item 13, wherein the cathode chamber is disposed so that at least one of the anion exchange fiber material laminated in the chamber and the anion exchange membrane and the negative electrode defining the chamber are in contact with each other. Desalination equipment.

  15. In the cathode chamber, the anionic exchange fiber material laminated in the chamber is disposed so as to come into contact with both the anion exchange membrane and the negative electrode that define the chamber. Salt equipment.

16. 14. The electrical desalination apparatus according to item 13, wherein an anion exchange fiber material is disposed along the surface of the anion exchange membrane and / or the negative electrode defining the chamber in the cathode chamber.
17. An electrical desalination apparatus having a desalination chamber, a concentration chamber, and an electrode chamber partitioned by a plurality of ion exchange membranes between a cathode and an anode, wherein the desalting chamber, the concentration chamber, and the electrode chamber are at least one chamber In this, the water-permeable porous material layer to which the ion exchange function is imparted is laminated and disposed so as to intersect the direction of water flow.

18. 18. The electric desalting apparatus according to item 17, wherein the water-permeable porous material provided with an ion exchange function is obtained by introducing an ion exchange group into a substrate using a radiation graft polymerization method.
19. 19. The electric desalination apparatus according to item 17 or 18 above, wherein the water-permeable porous material provided with an ion exchange function is disposed in at least a part of the desalination chamber.

20. 19. The electric desalting apparatus according to item 17 or 18, wherein the water-permeable porous material to which an ion exchange function is imparted is disposed in at least a part of the concentration chamber.
21. 21. The electrical desalination apparatus according to any one of items 17 to 20, wherein the water-permeable porous material provided with an ion exchange function is disposed in at least one of the electrode chambers.

  22. 19. The electric desalting apparatus according to item 17 or 18, wherein the water-permeable porous material to which an ion exchange function is imparted is disposed in at least a part of the desalting chamber and at least a part of the concentration chamber.

23. 23. The electrical desalting apparatus according to the above item 22, wherein the water-permeable porous material provided with an ion exchange function is disposed in at least one of the electrode chambers.
24. 24. The electrical desalination apparatus according to item 21 or 23, wherein the water-permeable porous material provided with a cation exchange function is disposed in the cathode chamber.

  25. An electrical desalination apparatus having a desalination chamber, a concentration chamber, and an electrode chamber partitioned by a plurality of ion exchange membranes between a cathode and an anode, wherein the desalting chamber, the concentration chamber, and the electrode chamber are at least one chamber The pleated surface of the pleated ion exchange fiber material structure is formed by stacking an anion exchange fiber material and a cation exchange fiber material in the form of a long sheet and folding them in accordance with the dimensions of the chamber. An electrical desalination apparatus characterized in that it is filled so as to intersect with the direction of water flow and both cross sections of the structure are in contact with a cation exchange membrane and an anion exchange membrane that define the chamber.

  26. An electrical desalination apparatus having a desalination chamber, a concentration chamber, and an electrode chamber partitioned by a plurality of ion exchange membranes between a cathode and an anode, wherein the desalting chamber, the concentration chamber, and the electrode chamber are at least one chamber A roll-like structure formed by overlapping and winding a long sheet-like anion exchange fiber material and a cation exchange fiber material into a cation exchange membrane and an anion exchange membrane in which both cross sections of the structure define the chamber An electric desalination apparatus, wherein one or more are filled so as to contact each other.

27. The electrical desalting apparatus according to any one of the first to fifth aspects, wherein an anion exchange fiber material is laminated and disposed in the cathode chamber so as to intersect the water flow direction.
28. 28. The electrical desalting apparatus according to item 27, wherein the anion exchange fiber material is disposed so as to be in contact with at least one of an anion exchange membrane and a negative electrode that define the cathode chamber.

29. 28. The electrical desalting apparatus according to item 27, wherein the anion exchange fiber material is disposed so as to contact both the anion exchange membrane and the negative electrode that define the cathode chamber.
30. 28. The electrical desalting apparatus according to the above 27th aspect, wherein an anion exchange fiber material is disposed along the surface of the anion exchange membrane and / or the negative electrode defining the chamber in the cathode chamber.

Hereinafter, the present invention will be described in more detail using specific examples. The following description shows specific examples of the present invention, and the present invention is not limited to these descriptions.
[Production Example 1: Production of cation exchange nonwoven fabric]
As a base material, a heat-sealed nonwoven fabric having a basis weight of 55 g / m ² and a thickness of 0.35 mm made of a composite fiber of polyethylene (sheath) / polypropylene (core) having a fiber diameter of 17 μm was used. The nonwoven fabric substrate was irradiated with an electron beam (150 kGy) in a nitrogen atmosphere. The irradiated nonwoven substrate was immersed in a 10% methanol solution of glycidyl methacrylate and reacted at 45 ° C. for 4 hours. After the reaction, the nonwoven fabric base material is immersed in a dimethylformamide solution at 60 ° C. for 5 hours to remove the monomer polymer (homopolymer) not bonded to the base material, and the nonwoven fabric material graft-polymerized with glycidyl methacrylate ( A graft ratio of 131%) was obtained. This grafted nonwoven fabric was immersed in a solution of sodium sulfite: isopropyl alcohol: water = 1: 1: 8 (weight ratio) and reacted at 80 ° C. for 10 hours to introduce sulfonic acid groups, and then hydrochloric acid (5 wt% ) To obtain a strongly acidic cation exchange nonwoven fabric (neutral salt decomposition capacity 471 meq / m ² ). This was designated as “cation exchange nonwoven fabric”.

[Production Example 2: Production of anion exchange nonwoven fabric]
The same nonwoven fabric substrate as in Production Example 1 was irradiated with an electron beam (150 kGy) in a nitrogen atmosphere. Chloromethylstyrene (product name: CMS-AM, manufactured by Seimi Chemical Co., Ltd.) was passed through the activated alumina packed bed to remove the polymerization inhibitor, and nitrogen aeration was performed. The nonwoven fabric substrate that had been irradiated with the electron beam was immersed in the chloromethylstyrene solution after the deoxygenation treatment and reacted at 50 ° C. for 6 hours. Thereafter, the nonwoven fabric was taken out from the chloromethylstyrene solution, immersed in toluene for 3 hours to remove the homopolymer, and a nonwoven fabric material grafted with chloromethylstyrene (grafting rate 161%) was obtained. This graft nonwoven is quaternized in a trimethylamine solution (10% by weight) and then regenerated with an aqueous sodium hydroxide solution (5% by weight) to give a strongly basic anion exchange nonwoven having a quaternary ammonium group. (Neutral salt decomposition capacity 350 meq / m ² ) was obtained. This was designated as “anion exchange nonwoven fabric”.

[Production Example 3: Production of cation conductive spacer]
As the base material of the ion conductive spacer, a polyethylene oblique network having a thickness of 1.2 mm and a pitch of 3 mm was used, sodium styrenesulfonate as a graft monomer and acrylic acid as an auxiliary monomer.

While cooling with dry ice, γ-rays (150 kGy) were irradiated to a polyethylene oblique mesh in a nitrogen atmosphere. This irradiated oblique network is immersed in a mixed monomer solution of sodium sulfonate and acrylic acid and reacted at 75 ° C. for 3 hours to obtain a graft oblique network material (cation conducting spacer) having a sulfonic acid group and a carboxyl group. Obtained (graft rate 153%). The neutral salt decomposition capacity was 189 meq / m ² and the total exchange capacity was 834 meq / m ² . This was designated as “cation conductive spacer”.

[Production Example 4: Production of anion conducting spacer]
While cooling with dry ice, the same polyethylene oblique mesh as in Production Example 3 was irradiated with γ rays (150 kGy) in a nitrogen atmosphere. This irradiated oblique network was immersed in a mixed monomer of VBTAC (vinylbenzyltrimethylammonium) and DMAA (dimethylacrylamide) and reacted at 50 ° C. for 3 hours to obtain a grafted oblique network of VBTAC and DMAA. The graft ratio was calculated to be 156%. The neutral salt decomposition capacity of the obtained grafted oblique network was calculated to be 198 meq / m ² . This was designated as “anion conducting spacer”.

[Example 1]
An electric desalination apparatus having the configuration shown in FIG. 6 was assembled. By arranging a cation exchange membrane C (manufactured by Tokuyama: NEOSEPTA CMB) and an anion exchange membrane A (manufactured by Tokuyama: NEOSEPTA AHA) as shown in FIG. 6 between the cathode and the anode, the anode chamber is concentrated from the anode side. An electric desalination apparatus arranged in the order of a chamber, a desalting chamber, a concentration chamber, and a cathode chamber was constructed. The thickness of the desalting chamber was 20 mm, the size of the electrode was 50 mm long × 50 mm wide, and the thickness of the concentration chamber and the electrode chamber was 3 mm. In the desalting chamber, the cation exchange nonwoven fabric produced by Production Example 1 and regenerated with hydrochloric acid, and the anion exchange nonwoven fabric produced by Production Example 2 and regenerated by alkali, as shown in FIG. On the other hand, 25 sheets were alternately stacked and filled in the crossing direction (that is, horizontally). In both concentrating chambers, two anion conducting spacers produced in Production Example 4 are arranged on the anion exchange membrane in parallel with the anion exchange membrane, and 2 cation conducting spacers produced in Production Example 3 are placed on the cation exchange membrane surface. The plates were placed in parallel with the cation exchange membrane. Further, four cation conductive spacers manufactured in Production Example 3 are arranged in the anode chamber in parallel to the cation exchange membrane, and four anion conductive spacers manufactured in Production Example 4 are arranged in the cathode chamber in parallel to the anion exchange membrane. Placed.

Applying 0.4A direct current between both electrodes, 0.2MΩcm RO treated water (reverse osmosis membrane treated water: silica concentration 0.1-0.3ppm, water temperature 14 ° C-26 ° C, TOC concentration 120ppb) Is passed through the desalting chamber at a flow rate of 10 Lh ⁻¹ (SV = 200 h ⁻¹ ), and 0.2 MΩcm of RO-treated water is serially connected from the cathode side electrode chamber to the cathode side concentration chamber for the concentration chamber and electrode chamber. Water was passed through the anode side electrode chamber in series from the anode side electrode chamber to the anode side concentrating chamber at 2.5 Lh- ¹ . As a result, 18.2 MΩcm of water was obtained from the desalting chamber as demineralized water after 1 minute of operation, and 18.0 MΩcm or more of water was stably obtained even after 1000 hours of operation. FIG. 7 is a graph showing the change over time in the specific resistance of the treated water up to 1200 hours of operation. Further, the TOC concentration of the treated water was 7.2 ppb after 25 hours, and reached the equilibrium value at 5.3 ppb. The pressure loss in the desalination chamber was 0.5 kgf / cm ² after 1000 hours of operation.

[Comparative Example 1]
A water passage test was conducted using a conventional electric desalination apparatus in which the ion exchange fiber material and the ion conductive spacer were filled in the desalting chamber / concentration chamber in parallel with the flow direction of the water to be treated. As shown in FIG. 8, a conventionally known type of electric desalination apparatus having three desalination chambers by alternately arranging an anion exchange membrane (A) and a cation exchange membrane (C) between electrodes. Assembled. The thickness of each desalting chamber cell and each electrode chamber was 2.5 mm, the thickness of each concentrating chamber was 1.5 mm, and the electrode size was 240 mm long × 50 mm wide. The same ion exchange membrane as in Example 1 was used. In each desalting chamber, the anion exchange nonwoven fabric produced in Production Example 2 is placed on the anion exchange membrane surface, and the cation exchange nonwoven fabric produced in Production Example 1 is placed on the cation exchange membrane surface one by one. Two anion conducting spacers prepared in Example 4 were filled. In each concentrating chamber, one anion conducting spacer produced in Production Example 4 was filled on the anion exchange membrane surface, and one cation conducting spacer produced in Production Example 3 on the cation exchange membrane surface. In the anode chamber, four cation conducting spacers produced in Production Example 3 were arranged, and in the cathode chamber, four anion conducting spacers produced in Production Example 4 were arranged.

Applying a direct current of 0.13 A between both electrodes, 0.2 MΩcm RO treated water (reverse osmosis membrane treated water: silica concentration 0.1 to 0.3 ppm, water temperature 14 ° C. to 26 ° C., TOC concentration 120 ppb) At a flow rate of 5 Lh ⁻¹ (SV = 55.6 h ⁻¹ ) in series with the desalting chambers D1, D2 and D3, and for the concentration chamber and the electrode chamber, 0.2 MΩcm RO-treated water is used as the cathode. Water was passed in series from the side electrode chamber (K2) through the concentration chambers C2 and C1 to the anode side electrode chamber (K1) at 2.5 Lh- ¹ . As a result, 17.9 MΩcm water was obtained as demineralized water after 100 hours, and 17.6 MΩcm water was obtained even after 1000 hours of operation. Further, the TOC concentration of treated water became 10 ppb after 200 hours, and reached an almost equilibrium value at 9.2 ppb. After 1000 hours of operation, the desalination chamber pressure loss was 0.5 kgf / cm ² per three chambers.

When the same experiment was conducted with the same equipment, increasing the flow rate to the desalination chamber to 20 Lh ^-1 (SV = 222 h ^-1 ) and increasing the flow rate to the concentration chamber to 10 Lh ^-1 , the water quality increased with the passage of operating time. However, the water quality of 1.3 MΩcm was obtained even after 1000 hours of operation. After 1000 hours of operation, the pressure loss in the desalting chamber was 2.3 kgf / cm ² per three chambers.

[Comparative Example 2]
A water passage test was conducted using a conventional electric desalting apparatus in which a desalting chamber / concentration chamber was filled with ion-exchange resin beads. As shown in FIG. 9, a conventionally known type electric desalination apparatus having nine desalination chambers was assembled. The thickness of the desalination chamber cell was 3 mm, the thickness of the concentration chamber and the electrode chamber was 3 mm, and the electrode size was 220 mm long × 35 mm wide. The same ion exchange membrane as in Example 1 was used. In each desalting chamber, each concentrating chamber, and both electrode chambers, cation resin beads (Dow Chemical Dowex MONOSPHERE 650C) and anion exchange resin (Dow Chemical Dowex MONOSPHERE 550A) were used. The mixed bed was filled. Applying a direct current of 0.1 A between both electrodes, 0.2 MΩcm RO treated water (reverse osmosis membrane treated water: silica concentration 0.1 to 0.3 ppm, water temperature 14 ° C. to 26 ° C., TOC concentration 120 ppb) At a flow rate of 12 Lh ⁻¹ (SV = 57.7 h ⁻¹ ), water was passed through the desalting chamber as shown in FIG. 9, and 0.2 MΩcm RO treated water was added to the cathode side for the concentration chamber and the electrode chamber. As shown in FIG. 9, water was passed from the polar chamber (K2) through the concentration chambers to the anode-side polar chamber (K1) at 6 Lh ⁻¹ . As a result, a water quality of 4.3 MΩcm was obtained after 1000 hours of operation, and the TOC concentration of treated water was 20 ppb after 1000 hours. After 1000 hours of operation, the pressure loss in the desalting chamber was 0.8 kgf / cm ² .

When the same experiment was conducted with the same equipment, increasing the flow rate to the desalination chamber to 36 Lh ^-1 (SV = 173h ^-1 ) and increasing the flow rate to the concentration chamber to 18 Lh ^-1 , the water quality increased with the passage of operating time. However, water quality of 0.5 MΩcm was obtained even after 1000 hours of operation. The TOC concentration of the treated water was 15 ppb after 1000 hours, and the pressure loss in the desalting chamber was 2.5 kgf / cm ² .

  As is clear from Example 1 and Comparative Examples 1 and 2 described above, according to the electric desalination apparatus of the present invention, the quality of treated water is excellent at a raw water flow rate much higher than that of the conventional electric desalination apparatus. Could get. Moreover, since the apparatus was downsized, the pressure loss in the desalination chamber was not a problem.

[Example 2]
An electric desalination apparatus having the configuration shown in FIG. 10 was assembled. By arranging a cation exchange membrane C (manufactured by Tokuyama: NEOSEPTA CMB) and an anion exchange membrane A (manufactured by Tokuyama: NEOSEPTA AHA) as shown in FIG. 10 between the cathode and the anode, the anode chamber, An electric desalination apparatus arranged in the order of a concentration chamber, a desalting chamber, a concentration chamber, and a cathode chamber was constructed. The thickness of the desalting chamber and the concentration chamber was 20 mm, the size of the electrode was 50 mm long × 50 mm wide, and the thickness of the electrode chamber was 3 mm. In the desalination chamber and the concentration chamber, the cation exchange nonwoven fabric produced by Production Example 1 and regenerated with hydrochloric acid, and the anion exchange nonwoven fabric produced by Production Example 2 and regenerated by alkali, as shown in FIG. 25 sheets were stacked and filled alternately in a direction crossing the water flow direction (that is, horizontally). In the anode chamber, four cation conducting spacers produced in Production Example 3 are arranged in parallel to the cation exchange membrane, and in the cathode chamber, four anion conducting spacers produced in Production Example 4 are arranged in parallel to the anion exchange membrane. Arranged.

A 0.4 A direct current was applied between both electrodes, and 0.2 MΩcm RO-treated water (reverse osmosis membrane treated water: silica concentration 0.1 to 0.3 ppm, water temperature 14 ° C. to 26 ° C., TOC concentration 120 ppb, carbonate concentration 6.5 ppm, a calcium concentration 208ppb), Rohm & desalting compartment at a flow rate ^{20Lh -1 (SV = 400h -1)} , for both concentrating chambers of RO treated water 0.2MΩcm in 12Lh ^-1 through In each of the polar chambers, 0.2 MΩcm RO-treated water was passed at 8 Lh ⁻¹ . As a result, after 1 minute of operation, 18.2 MΩcm water was obtained from the desalting chamber as desalted water. The operating voltage after 30 hours was 40.75V. Further, the voltages applied to both ends of the cathode side concentrating chamber and the anode chamber at this time were 4.87 V and 2.71 V, respectively. Subsequently, continuous operation was performed for 2000 hours, and the operating voltage and the change with time of the voltage applied to both ends of both the concentrating chamber and the desalting chamber were measured. The results are shown in FIG. At the beginning of operation, the operating voltage and the voltage applied to both ends of the concentrating chamber gradually increased, but the voltage applied to both ends of the concentrating chamber became almost constant after about 200 hours, and the rate of increase in operating voltage was extremely small at about 500 hours. became. The operating voltage after 2000 hours was 130V, and the voltage applied to both ends of the cathode side concentrating chamber was 8.0V. After the operation, the apparatus was disassembled and the ion exchange nonwoven fabric in the concentration chamber was observed, but no precipitation of scale was observed.

  Note that the voltage applied to both ends of the concentrating chamber is the same as that in the desalination apparatus having the configuration shown in FIG. 10, the cation exchange membrane side in the anode chamber, the anion exchange membrane side in the anode concentrating chamber, the cation exchange membrane side in the cathode concentrating chamber, Measurement was performed by loading a platinum electrode wire (0.4 mm in diameter) on the anion exchange membrane side of the chamber and measuring the potential difference between the electrodes.

[Comparative Example 3]
An electric desalination apparatus having the configuration shown in FIG. 11 was assembled. By arranging a cation exchange membrane C (manufactured by Tokuyama: NEOSEPTA CMB) and an anion exchange membrane A (manufactured by Tokuyama: NEOSEPTA AHA) as shown in FIG. 11 between the cathode and the anode, the anode chamber, An electric desalination apparatus arranged in the order of a concentration chamber, a desalting chamber, a concentration chamber, and a cathode chamber was constructed. The thickness of the desalting chamber was 20 mm, the size of the electrode was 50 mm long × 50 mm wide, and the thickness of the concentration chamber and the electrode chamber was 3 mm. In the desalting chamber, the cation exchange nonwoven fabric produced by Production Example 1 and regenerated with hydrochloric acid, and the anion exchange nonwoven fabric produced by Production Example 2 and regenerated by alkali, as shown in FIG. Each of 25 sheets was stacked and filled alternately in a direction intersecting with (ie, horizontally). In both concentrating chambers, one anion conducting spacer produced in Production Example 4 is disposed on the anion exchange membrane in parallel with the anion exchange membrane, and the cation conducting spacer produced in Production Example 3 is placed on the surface of the cation exchange membrane. The plates were placed in parallel with the cation exchange membrane. Further, four cation conductive spacers manufactured in Production Example 3 are arranged in the anode chamber in parallel to the cation exchange membrane, and four anion conductive spacers manufactured in Production Example 4 are arranged in the cathode chamber in parallel to the anion exchange membrane. Placed.

A 0.4 A direct current was applied between both electrodes, and 0.2 MΩcm RO-treated water (reverse osmosis membrane treated water: silica concentration 0.1 to 0.3 ppm, water temperature 14 ° C. to 26 ° C., TOC concentration 120 ppb, carbonate concentration 6.5 ppm, a calcium concentration 208Ppb), flow rate 20Lh ^-1 (SV = Rohm & desalting chamber 400h ^-1), for both concentration compartment, the RO treated water, respectively 0.2MΩcm 12Lh ^-1 In each chamber, 0.2 MΩcm RO-treated water was passed at 8 Lh ⁻¹ . As a result, after 1 minute of operation, 18.2 MΩcm water was obtained from the desalting chamber as desalted water. The operating voltage after 30 hours was 81.2V. At this time, the voltage applied to both ends of the cathode side enrichment chamber and the anode side enrichment chamber was 11.9V and 13.1V, respectively. Subsequently, continuous operation was performed for 2000 hours, and the operating voltage and the change with time of the voltage applied to both ends of both the concentrating chamber and the desalting chamber were measured. The results are shown in FIG. Compared with the result of Example 2 shown in FIG. 12, the degree of increase in the operating voltage and the voltage applied to both ends of both concentrating chambers was extremely large, and it was still on an increasing trend even after 1000 hours of operation. The operating voltage after 2000 hours was 293.9 V, the voltage applied to both ends of the cathode side enrichment chamber was 44.0 V, and the voltage applied to both ends of the anode side enrichment chamber was 82.7 V.

  When the apparatus was disassembled after 2000 hours of operation and the ion conductive spacer in the concentrating chamber was observed, the scale of calcium carbonate was vigorously precipitated throughout the spacer. First, it is considered that a crystal of calcium carbonate was precipitated at the contact portion between the anion conductive spacer and the cation conductive spacer, and this became a seed nucleus and crystal was precipitated on the entire spacer.

  Comparing Example 2 and Comparative Example 3, in Example 2 in which the anion exchange nonwoven fabric and the cation exchange nonwoven fabric were laminated and filled horizontally in the direction intersecting the liquid passage direction in the concentration chamber, It can be seen that the stability of the operating voltage is excellent. According to the observation after disassembling the apparatus after long-time operation, it is considered that the stability of the operation voltage is mainly due to the fact that calcium carbonate scale precipitation is unlikely to occur in the concentration chamber.

[Example 3]
An electric desalination apparatus having the configuration shown in FIG. 14 was assembled. A cation exchange membrane C (manufactured by Tokuyama: NEOSEPTA CMB) and an anion exchange membrane A (manufactured by Tokuyama: NEOSEPTA AHA) are arranged between the cathode and the anode as shown in FIG. An electric desalination apparatus arranged in the order of a concentration chamber, a desalting chamber, a concentration chamber, and a cathode chamber was constructed. The thickness of the desalting chamber and the concentration chamber was 20 mm, the size of the electrode was 50 mm long × 50 mm wide, and the thickness of the electrode chamber was 5 mm. In the desalination chamber and the concentration chamber, the cation exchange nonwoven fabric produced by Production Example 1 and regenerated with hydrochloric acid and the anion exchange nonwoven fabric produced by Production Example 2 and regenerated by alkali are treated water as shown in FIG. Each of 25 sheets was alternately stacked and filled in a direction intersecting with the flow direction (that is, horizontally placed). In the anode chamber, 50 cation exchange nonwoven fabrics produced in Production Example 1 were stacked and filled in a direction (horizontal placement) intersecting the water flow direction as shown in FIG. In the cathode chamber, 50 anion exchange nonwoven fabrics produced in Production Example 2 were stacked and filled in a direction intersecting the water passage direction (horizontal placement) as shown in FIG.

A 0.4 A direct current was applied between both electrodes, and 0.2 MΩcm RO-treated water (reverse osmosis membrane treated water: silica concentration 0.1 to 0.3 ppm, water temperature 14 ° C. to 26 ° C., TOC concentration 120 ppb, carbonate concentration 6.5 ppm, a calcium concentration 208Ppb), flow rate 20Lh ^-1 (SV = Rohm & desalting chamber 400h ^-1), for both concentration compartment, the RO treated water, respectively 0.2MΩcm 12Lh ^-1 In each chamber, 0.2 MΩcm RO-treated water was passed at 8 Lh ⁻¹ . As a result, after 1 minute of operation, 18.2 MΩcm water was obtained from the desalting chamber as desalted water. The operating voltage after 30 hours was 36.6V. At this time, the voltages applied to both ends of the cathode chamber and the anode chamber were 5.25 V and 2.71 V, respectively. Subsequently, continuous operation for 2000 hours was performed, and the change over time of the operating voltage and the voltage applied to both ends of both electrode chambers was measured. The results are shown in FIG. The voltage applied to both ends of both electrode chambers shows a stable and low value from the beginning of operation. After 2000 hours of operation, the operating voltage is 76.6 V, and the voltages applied to both ends of the cathode chamber and anode chamber are 5. 33V and 1.65V. On the other hand, FIG. 17 shows the change with time of the voltage applied to both ends of the bipolar chamber measured in the operation of the electrical desalting apparatus of Example 2.

  Compared with the results of Example 2 shown in FIG. 17, it can be seen that in Example 3 in which the anion exchange nonwoven fabrics were horizontally stacked in the cathode chamber, the increase in voltage applied to both ends of the cathode chamber was greatly suppressed.

[Example 4]
An electric desalination apparatus having the configuration shown in FIG. 15 was assembled. By arranging a cation exchange membrane C (manufactured by Tokuyama: NEOSEPTA CMB) and an anion exchange membrane A (manufactured by Tokuyama: NEOSEPTA AHA) as shown in FIG. 15 between the cathode and the anode, the anode chamber, An electric desalting apparatus arranged in the order of a concentrating chamber, a desalting chamber, and a concentrating chamber (also serving as a cathode chamber) was constructed. The thickness of the desalting chamber, the concentration chamber, and the concentration chamber / cathode chamber was 20 mm, the electrode size was 50 mm long × 50 mm wide, and the thickness of the anode chamber was 5 mm. In the desalination chamber, the concentration chamber, and the concentration chamber / cathode chamber, the cation exchange nonwoven fabric produced in Production Example 1 and regenerated with hydrochloric acid and the anion exchange nonwoven fabric produced in Production Example 2 and regenerated with alkali are shown in FIG. As shown, 25 sheets were alternately stacked and filled in a direction intersecting with the flow direction of the water to be treated (that is, horizontally). In the anode chamber, 50 cation exchange nonwoven fabrics produced in Production Example 1 were stacked and filled in a direction crossing the water flow direction (horizontal placement) as shown in FIG.

A 0.4 A direct current was applied between both electrodes, and 0.2 MΩcm RO-treated water (reverse osmosis membrane treated water: silica concentration 0.1 to 0.3 ppm, water temperature 14 ° C. to 26 ° C., TOC concentration 120 ppb, Carbonate concentration 6.5ppm, calcium concentration 208ppb) was passed through the desalting chamber at a flow rate of 20Lh- ¹ (SV = 400h- ¹ ), and 0.2MΩcm RO treated water was passed through the concentration chamber at 12Lh- ^1. Then, RO treated water of 0.2 MΩcm was passed through the anode chamber and the concentration chamber / cathode chamber at 8 Lh ⁻¹ , respectively. As a result, after 1 minute of operation, 18.2 MΩcm water was obtained from the desalting chamber as desalted water. The operating voltage after 30 hours was 33.4V. At this time, the voltages applied to both ends of the concentration chamber / cathode chamber and the anode chamber were 6.71 V and 1.71 V, respectively. Subsequently, continuous operation was performed for 2000 hours, and changes with time in the operating voltage and the voltage applied to both ends of the anode chamber and the concentration chamber / cathode chamber were measured. The results are shown in FIG. The voltage applied to both ends of the anode chamber and the concentration chamber / cathode chamber is stable and low from the beginning of the operation. After 2000 hours of operation, the operation voltage is 73.9 V, the concentration chamber / cathode chamber and the anode chamber are The voltages applied to both ends were 9.84V and 1.78V, respectively.

Industrial applicability

  According to the present invention, in the desalting chamber, a conventional desalting chamber structure in which the ion exchange fiber material is horizontally stacked and filled in a direction crossing the liquid flow direction is used. Pure water with high purity (high specific resistance and low TOC) can be stably obtained by an apparatus much smaller than a desalting apparatus. Moreover, since the apparatus can be miniaturized, the problem of pressure loss due to filling only the fiber material into the desalting chamber is not so great. Further, in the concentrating chamber and further in the polar chamber, it is possible to suppress the problem of increase in operating voltage due to the precipitation of calcium carbonate by adopting the same structure as the desalting chamber.

FIG. 1 is a conceptual diagram showing the principle of an electric desalination apparatus. FIG. 2 is a conceptual diagram illustrating a configuration of an electrical desalination apparatus according to one embodiment of the present invention. FIG. 3 is a conceptual diagram showing a configuration of an electrical desalination apparatus according to another aspect of the present invention. FIG. 4 is a conceptual diagram showing a configuration of a desalting chamber of an electric desalination apparatus according to another aspect of the present invention. FIG. 5 is a conceptual diagram showing a configuration of a desalting chamber of an electric desalination apparatus according to another aspect of the present invention. FIG. 6 is a conceptual diagram showing the configuration of the electric desalting apparatus of the present invention used in Example 1. FIG. 7 is a graph showing the water flow experiment results of Example 1. FIG. 8 is a conceptual diagram showing a configuration of a conventional electric desalination apparatus used in Comparative Example 1. FIG. 9 is a conceptual diagram showing a configuration of a conventional electric desalination apparatus used in Comparative Example 2. FIG. 10 is a conceptual diagram showing the configuration of the electrical desalting apparatus according to the second aspect of the present invention used in Example 2. FIG. 11 is a conceptual diagram showing the configuration of the electrical desalting apparatus used in Comparative Example 3. FIG. 12 is a graph showing the results of the operation experiment of Example 2. FIG. 13 is a graph showing the results of an operation experiment of Comparative Example 3. FIG. 14 is a conceptual diagram showing the configuration of the electrical desalting apparatus according to the third aspect of the present invention used in Example 3. FIG. 15 is a conceptual diagram showing the configuration of the electrical desalting apparatus according to the third aspect of the present invention used in Example 4. FIG. 16 is a graph showing the results of an operation experiment of Example 3. FIG. 17 is a graph showing the change with time of the voltage applied to both ends of the bipolar chamber in the operation experiment of Example 2. FIG. 18 is a graph showing the results of the driving experiment of Example 4.

Claims (1)

  An electrical desalination apparatus having a desalting chamber, a concentrating chamber, and an electrode chamber partitioned between a cathode and an anode by a plurality of ion exchange membranes, wherein the desalting chamber, the concentrating chamber, and the electrode chamber are at least one chamber In addition, at least one of the layer of anion exchange fiber material and the layer of cation exchange fiber material is laminated | stacked and arrange | positioned so that a water flow direction may cross | intersect.

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