JP2003190963A - Ion exchanger and electric demineralizer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric demineralizer which can be operated at low voltage for a long time, and an ion exchanger which is disposed in a demineralization chamber and/or a concentration chamber. <P>SOLUTION: The ion exchanger is deposed in the demineralization chamber and/or the concentration chamber of the electric demineralizer where cation exchange membranes and anion exchange membranes are set between an anode and a cathode so that they are alternately disposed at least partially, thereby forming demineralization chambers and concentration chambers. The ion exchanger has ion exchange groups having an electric charge of either of an anion or a cation, and a powdered ion exchange resin having an electric charge opposite to that of the ion exchange groups is introduced into the ion exchanger. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ion exchanger suitable for use in a so-called electric desalination apparatus and an electric desalination apparatus. In particular, an ion exchanger for an electric desalination device capable of sustaining the dissociation of water, particularly an ion exchange nonwoven fabric for an electric desalination device and an ion exchanger for an electric desalination device which is optimal as an ion conductive spacer, and an electric deionization device. The present invention relates to an electric desalination device that can suppress a voltage rise of a salt device and can be operated at a low voltage.

[0002]

2. Description of the Related Art An electric demineralizer is a cation exchange membrane and anion exchange membrane arranged between an anode and a cathode to alternately form a concentrating chamber and a desalting chamber, using a potential gradient as a driving source.
In the desalination chamber, the ions in the liquid to be treated are moved and separated through the ion exchange membrane to the concentration chamber to remove the ionic components in the liquid.

FIG. 1 shows the concept of a typical electric desalination apparatus. 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. There is. By further repeating the alternating arrangement of the anion exchange membrane and the cation exchange membrane, a plurality of desalting chambers are formed in parallel. If necessary, the desalting chamber or the concentration chamber is filled with an ion exchanger to promote the movement of ions inside the chamber. Further, the compartments in contact with the anode and the cathode at both ends are generally called an anode chamber and a cathode chamber. Of these polar chambers, the most concentrated chamber on the electrode side may be used as the polar chamber, or an ion exchange membrane may be arranged further on the electrode side of the most concentrated chamber on the electrode side to form an independent polar chamber. In some cases. In the former case, the ion exchange membrane on the most cathode side is a cation exchange membrane, the ion exchange membrane on the most anode side is an anion exchange membrane, and in the latter case, the ion exchange membrane on the most cathode side is an anion exchange membrane, The ion exchange membrane closest to the cathode is a cation exchange membrane. Here, the polar chamber has a function of exchanging electrons of a current applied by a direct current. In the operation of such an electric deionization apparatus, a voltage is applied to the anode and the cathode, and water is supplied to the deionization chamber, the concentration chamber, and the bipolar chamber. The water supplied to the concentrating chamber is called concentrated water, and the water supplied to the desalting chamber is called treated water. In this way, when the water to be treated and the concentrated water are introduced into the desalting chamber and the concentrating chamber, respectively, the cations and anions in the water are drawn to the cathode side and the anode side, respectively, but the ion exchange membrane selectively selects only ions of the same kind. Since it permeates, cations (C
a ²⁺ , Na ⁺ , Mg ²⁺ , H ^+, etc. ^pass through the cation exchange membrane C to the concentrating chamber on the cathode side, and the anion (Cl
⁻ , SO ₄ ²⁻ , HSiO ₃ ⁻ , CO 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 anions from the concentration chamber to the desalting chamber and the movement of cations from the concentration chamber to the desalting chamber are blocked by the foreign ion blocking property of the ion exchange membrane. As a result, demineralized water with a reduced ion concentration is obtained from the demineralizing chamber, and concentrated water with an increased ion concentration is obtained from the concentrating chamber.

According to such an electric desalination apparatus, pure water having a higher purity can be obtained as desalted water by using, as the water to be treated, water having a small amount of impurities corresponding to RO (reverse osmosis) treated water. To be Recently, more advanced ultrapure water such as ultrapure water for semiconductor manufacturing has been required. Therefore, in the electric desalination device,
Alternatively, a method has been adopted in which the concentration chamber is mixed with cation exchange resin beads and anion exchange resin beads as an ion exchanger and filled to promote the movement of ions in these chambers. Further, as an ion exchanger, in a desalting chamber and / or a concentrating chamber, a cation exchange fiber material (nonwoven fabric or the like) may be disposed on the cation exchange membrane side, and an anion exchange fiber material may be disposed on the anion exchange membrane side. , A method of filling spacers or ion-conducting spacers having ion-conductivity between these ion-exchange fiber materials has also been proposed (PC
T / JP99 / 01391 International Publication WO99 / 48820).

In the electric desalination apparatus of such a system, there is a site where the cation exchange group and the anion exchange group come into contact with each other in the deionization chamber and / or the concentration chamber filled with the ion exchanger. Especially in the desalting chamber, as shown in FIG.
As shown in (a), water dissociation (H ₂ O → H ⁺ + O
H ⁻ ) occurs, and H ⁺ ions and OH ⁻ ions generated by the dissociation (hydrolysis) of this water continuously and efficiently regenerate the ion exchanger in the desalination chamber, thereby producing high-purity ultrapure water. It has become possible to obtain. This is achieved by arranging spacers or ion-conducting spacers between the cation-exchange fiber material and the anion-exchange fiber material in the desalting chamber and / or the concentrating chamber so that a continuous cation-exchanger packed layer and an anion-exchanger packed bed are formed. By forming
Since the ions easily passed to both electrodes, the counterion of the functional group was locally insufficient at the contact site between the cation exchanger and the anion exchanger, and water was dissociated to compensate for this insufficient counterion. To supply H ⁺ ions and OH ⁻ ions to the cation exchange group and the anion exchange group, and the number of cation exchange groups and the anion exchange groups is several Å.
It is considered that when they are close to each other at a distance of tens of Å, a strong electric field is generated between them, water is easily polarized and dissociated, and the ion exchanger is regenerated without recombination. Further, it is considered that not only water but also non-electrolytes such as alcohol can be adsorbed to the functional group and removed by becoming anions and cations polarized and dissociated by a strong electric field.

However, even in the electric desalination apparatus having such a structure, there arises a problem that the operating voltage increases due to long-term operation. That is, as shown in FIG. 2B, the electric field generated at the dissociation site of water, that is, the contact site between the cation exchange group and the anion exchange group attracts the cation exchange group and the anion exchange group to each other to form an ionic bond. When formed, free ion-exchange groups that bind to H ⁺ and OH ⁻ ions are reduced and the electric field at the contact site is weakened. Then, the energy for dissociating water is insufficient, water is less likely to dissociate between the cation exchange group and the anion exchange group, and the regeneration ability of the ion exchanger is reduced. In order to maintain the regeneration ability of the ion exchanger, it is necessary to further supply electric energy from the outside to give a strong electric field, and as a result, it is considered that the operating voltage rises.

[0007] In short, in the ion exchanger used in the conventional electric desalting apparatus, the bond is promoted by direct contact between the ion exchange groups and the ion exchange ability is deteriorated with long-term use. However, there has been a problem that it is necessary to apply a high voltage from the outside in order to compensate for this decrease in ion exchange capacity, and the advantages of the resource-saving and energy-saving electric desalination apparatus are impaired.

[0008]

Therefore, according to the present invention, even when the electric desalination apparatus is operated for a long time, the desalination chamber and / or
Or, to prevent direct contact between the ion-exchange groups of the ion-exchanger in the concentration chamber, without inhibiting the dissociation of water,
It is an object of the present invention to provide an ion exchanger for an electric desalination apparatus capable of maintaining a low operating voltage and an electric desalination apparatus in which the ion exchanger is arranged.

[0009]

The present invention has been made to solve the above problems, and a powder having a large particle size between the anion exchange group and the cation exchange group in the desalting chamber and / or the concentrating chamber. By positioning the ion-exchange resin, the distance between the anion-exchange group and the cation-exchange group is increased to prevent direct contact between the two and reduce the bond between the two, resulting in dissociation of water between the two. Is configured to be continued for a long time.

That is, according to the present invention, an electric system in which a cation exchange membrane and an anion exchange membrane are alternately arranged at least partially between the anode and the cathode to form a desalination chamber and a concentration chamber. In the ion exchanger arranged in the desalting chamber and / or the concentrating chamber of the desalting apparatus, the ion exchanger has an ion exchange group having a charge of either cation or anion, and further the ion exchange A powder ion exchange resin having an electric charge opposite to that of the base is introduced, and an ion exchanger for an electric desalination apparatus, and the ion exchanger for the electric desalination apparatus are desalted and / or concentrated. There is provided an electric desalination device arranged in a chamber. Incidentally, in the electric desalination apparatus according to the present invention, an ion exchanger, in particular,
The ion exchanger for an electric desalination apparatus according to the present invention is more preferably arranged at least in the desalination chamber.

The ion exchanger of the present invention is not particularly limited in shape and size and forming material as long as it has at least one kind of ion exchange group. For example, a fiber system such as beads, non-woven fabric or woven fabric. Introducing at least one ion-exchange group into a base material or a base material such as a spacer base material such as a diagonal net, and further introducing a powder ion-exchange resin, for example, an ion-exchange nonwoven fabric, an ion-exchange woven fabric, or an ion Preferable examples are ion exchangers composed of exchange nets, diagonal exchange networks, ion exchange membranes and the like.

As the ion-exchange resin beads which can be used as a base material for the ion exchanger of the present invention, those which are known in the art and which are produced by using beads obtained by crosslinking polystyrene with divinylbenzene as a base material resin are used. Can be used. For example, in the case of producing a strongly acidic cation exchange resin having a sulfone group, the above-mentioned base resin is treated with a sulfonating agent such as sulfuric acid or chlorosulfonic acid to be sulfonated, so that the base has a sulfone group. By introducing, a strongly acidic cation exchange resin is obtained. Further, for example, in the case of producing a strongly basic anion exchange resin having a quaternary ammonium group, the base resin is subjected to chloromethylation treatment, and then a tertiary amine such as trimethylamine is reacted to perform quaternary ammoniumation. As a result, a strongly basic anion exchange resin is obtained. Such production methods are known in the art, and ion exchange resin beads produced by such a method are, for example,
Dowex MONOSPHERE 650C (Dow Chemical), Amberlite IR-120B (Rohm & Haas) as cation exchange resin, Dowex MONOSPHERE 550 as anion exchange resin
A (Dow Chemical: Particle size 590 μm), Amberlite IRA-400
It is marketed under the product names such as (Rohm & Haas).

Further, the fibrous base material may be a single fiber composed of one kind of polymer such as polyolefin polymer such as polyethylene and polypropylene,
Further, it may be a composite fiber composed of polymers having different axial cores and sheaths. Examples of the conjugate fiber that can be used, polyolefin-based polymer, for example, polyethylene as a sheath component, a polymer other than those used as the sheath component,
For example, a composite fiber having a core-sheath structure containing polypropylene as a core component can be mentioned. These fibrous materials have a thickness of 0.1
~ 1.0 mm, the basis weight is 10 ~ 100 g / m ² , the porosity is 50 ~ 98%, the fiber diameter is preferably in the range of 10 ~ 70 μm in order to obtain good and stable treated water quality, especially the graft described below. Preferred when forming a polymer side chain. When a fibrous base material is used as the base material, compared to the case where a bead base material is used, the need for close packing of beads, the desalting chamber and / or the concentrating chamber due to the close packing of beads Since it is possible to eliminate the necessity of maintaining a high inflow pressure, the fear of uneven distribution due to the shape of the beads, the need for uniform mixing of the beads, the need for controlling the bead filling porosity, etc., in the present invention,
More preferable.

As the spacer base material, a polyolefin polymer resin, for example, a polyethylene cross net which has been conventionally used in an electrodialysis layer can be preferably mentioned. The spacer base material has a thickness of 0.5 to 2.0 mm, a pitch of 1.0 to 10 mm, and a fiber diameter of 0.1 to 1.0 m.
The range of m is preferable in order to obtain good and stable treated water quality, and is particularly preferable in the case of forming a side chain of the graft polymer described later. When a spacer base material is used as the base material, the water to be treated can be dispersed and flowed easily when the spacer base material is placed in an electric desalination apparatus and used, so that an increase in operating voltage can be significantly reduced. At the same time, there is no elution of organic carbon (TOC) components, which is preferable.

The ion exchange group that can be introduced into the ion exchanger of the present invention is not particularly limited, and various cation exchange groups or anion exchange groups can be used. For example, as a cation exchange group, a strong acidic cation exchange group such as a sulfone group, a medium acidic cation exchange group such as a phosphate group, a weak acidic cation exchange group such as a carboxyl group, and an anion exchange group include primary to primary A weakly basic anion exchange group such as a tertiary amino group and a strongly basic anion exchange group such as a quaternary ammonium group such as a trimethylammonium group, a triethylammonium group and a dimethylethanolammonium group can be used.

The ion exchanger for an electric desalination apparatus of the present invention is formed by introducing the above-mentioned various ion exchange groups into a side chain of a graft polymer formed on a substrate by a graft polymerization method. preferable. That is, graft polymerization was carried out using the above-mentioned monomers having various ion exchange groups, preferably radiation graft polymerization, or graft polymerization was carried out using polymerizable monomers having groups convertible to these ion exchange groups. It can be introduced into the fibrous base material or the spacer base material by subsequently converting the group into an ion exchange group. A monomer having an ion exchange group that can be used for this purpose is acrylic acid (AA
c), methacrylic acid, sodium styrenesulfonate (S
SS), sodium methacryl sulfonate, sodium allyl sulfonate, sodium vinyl sulfonate, vinyl benzyl trimethyl ammonium chloride (VBTA
C), diethylaminoethyl methacrylate (DMAEM
A), dimethylaminopropyl acrylamide (DMAPA
A) etc. can be mentioned. For example, by performing radiation graft polymerization using sodium styrene sulfonate as a monomer, a sulfonic acid group that is a strongly acidic cation exchange group can be directly introduced into the base material,
By carrying out radiation graft polymerization using vinylbenzyltrimethylammonium chloride as a monomer, a quaternary ammonium group which is a strongly basic anion exchange group can be directly introduced into the substrate. Examples of the monomer having a group that can be converted into an ion exchange group include acrylonitrile, acrolein, vinylpyridine, styrene, chloromethylstyrene, glycidyl methacrylate (GMA) and the like. For example, glycidyl methacrylate is introduced into a substrate by radiation-induced graft polymerization, and then a sulfonating group that is a strongly acidic cation exchange group is introduced by reacting with a sulfonating agent such as sodium sulfite, or chloromethylstyrene is grafted. After the polymerization, the base material is immersed in an aqueous trimethylamine solution for quaternary ammonium conversion, whereby a quaternary ammonium group which is a strongly basic anion exchange group can be introduced into the base material.

The above-mentioned radiation graft polymerization method is
It is a technique of introducing a monomer into a substrate by irradiating a polymer substrate with a radiation to form a radical and reacting the radical with the monomer. Examples of radiation that can be used in the radiation graft polymerization method include α rays, β rays, gamma rays, electron rays, and ultraviolet rays. In the present invention, gamma rays and electron rays are preferably used. The radiation graft polymerization method includes a pre-irradiation graft polymerization method in which a graft base material is previously irradiated with radiation and then brought into contact with a graft monomer to react, and a simultaneous irradiation graft polymerization method in which radiation is irradiated in the coexistence of the base material and the monomer. However, any method can be used in the present invention. Further, by the method of contacting the monomer and the base material, a liquid phase graft polymerization method in which the base material is immersed in the monomer solution to perform polymerization, a gas phase graft polymerization method in which the base material is brought into contact with the vapor of the monomer to perform polymerization, An example is an impregnated gas phase graft polymerization method in which the substrate is soaked in the monomer solution and then taken out from the monomer solution to carry out the reaction in the gas phase. Any method can be used in the present invention.

The ion exchanger for an electric desalination apparatus of the present invention further comprises a powder ion exchange resin having an electric charge opposite to that of the above-mentioned ion exchange group. When the ion exchange group introduced into the base material is a cation exchange group, a quaternary ammonium group, a tertiary amino group, a secondary amino group or a primary amino group can be further introduced as a powder ion exchange resin which can be introduced. When the ion exchange group introduced into the substrate is an anion exchange group, the powder ion exchange resin which can be further introduced is preferably a carboxyl group or a sulfone group.

The powder ion exchange resin which can be introduced into the ion exchanger for an electric desalination apparatus of the present invention includes powders and granules having a particle size of 10 to 200 μm.
By introducing a powder ion exchange resin having a particle size within the above range, steric hindrance may be caused to the extent of inhibiting ionic bonds between strongly acidic and strongly basic ion exchange groups, and between ion exchangers having different charges. It is possible to maintain an electric field at the contact site that does not hinder the dissociation of water. As such a powder ion exchange resin, a commercially available powder ion exchange resin can be used without particular limitation, and for example, “PD- which is manufactured and sold by Dow Chemical Co., Ltd. having a particle size of 60 μm.
1 ”and the like.

In the ion exchanger for an electric desalination apparatus of the present invention, the various powder ion exchange resins described above are prepared by converting an unintroduced ion exchanger into which no powder ion exchange resin has been introduced into a powder ion exchange resin suspension. By bringing them into contact with each other, they can be introduced by being attached to at least the surface of the ion exchanger. The impregnation of the powder ion-exchange resin onto the unintroduced ion exchanger is carried out, for example, by regenerating the above-mentioned various powder ion-exchange resins with a 5% sodium hydroxide aqueous solution or a 5% hydrochloric acid aqueous solution, and suspending the regenerated powder ion-exchange resin in water. Make it turbid and the concentration is 5
This can be carried out by preparing a 20 ppm powder ion-exchange resin suspension and contacting the powder ion-exchange resin suspension with the unintroduced ion exchanger for 10 to 60 seconds.

In the ion exchanger for an electric desalination apparatus of the present invention, the amount of the powdered ion exchange resin introduced should be 0.001% to 0.01% of the total ion exchange capacity of the introduced ion exchanger. preferable. By setting the amount of the powdered ion exchange resin to be 0.001% or more, it is possible to sufficiently prevent the direct contact between the anion exchange group and the cation exchange group, and suppress a remarkable increase in the operating voltage. You can On the other hand, by setting the amount of the powder ion exchange resin to be 0.01% or less, the ion exchange function of the ion exchanger is not deteriorated and the powder ion exchange resin is not dropped.

In the ion exchanger for an electric desalination apparatus of the present invention, the powder ion exchange resin may be impregnated on the surface of the unintroduced ion exchanger. Next, the function and effect of the ion exchanger for an electric desalination apparatus of the present invention will be described. In a general electric desalination apparatus, an ion exchanger disposed in a desalting chamber and / or a concentrating chamber has a cation exchange group at a contact portion with an ion exchanger or an ion exchange membrane having charges of opposite signs. Water is dissociated between the cation exchanger and the anion exchange group, and H ⁺ and OH ⁻ generated by the dissociation of water regenerates the cation exchanger and the anion exchanger, thereby enabling long-term operation. ing. In order to cause the dissociation of water, at least one of the cation exchanger and the anion exchanger arranged in the desalting chamber and / or the concentrating chamber must be a strongly acidic cation exchanger or a strongly basic anion exchanger. Is preferred. In particular, it is preferable to use a combination of a strongly acidic cation exchanger and a strongly basic anion exchanger. This is because the water dissociation that occurs between the cation exchanger and the anion exchanger occurs better due to the strong electric field generated between the strongly acidic cation exchange group and the strongly basic anion exchange group.
However, in this case, at the contact portion between the two, FIG.
As shown in the chemical reaction formula below, the cation exchange group and the anion exchange group are strongly attracted to each other by the strong electric field force, and the ionic bond between the cation exchange group and the anion exchange group proceeds, After long-term operation, the charges of the cation exchange group and the anion exchange group disappear, the electric field at the contact site disappears, and dissociation of H ⁺ and OH ⁻ ions is hindered.

[0023]

[Chemical 1]

The water dissociation section is arranged, for example, in the desalting chamber and / or the concentrating chamber with the cation exchange fiber material facing the cation exchange membrane and the anion exchange fiber material facing the anion exchange membrane. When it occurs, it occurs at the contact portion between the cation exchange fiber material and the anion exchange fiber material. Further, in the desalting chamber and / or the concentrating chamber, an ion conductive spacer provided with ion conductivity between the cation exchange fiber material arranged on the cation exchange membrane side and the anion exchange fiber material arranged on the anion exchange membrane side. When arranging, the contact portion between both ion-exchange fiber materials and the ion-conducting spacer having a charge of the opposite sign,
That is, it occurs at the contact portion between the cation exchange fiber material and the anion conducting spacer or at the contact portion between the anion exchange fiber material and the cation conducting spacer. Furthermore, when the anion-conducting spacer and the cation-conducting spacer are arranged between the two ion-exchange fiber materials, they occur at the contact portion between the anion-conducting spacer and the cation-conducting spacer.

The ion exchanger of the present invention has an ion exchange group having a cation or anion charge, and a powder ion exchange resin having an opposite charge to the ion exchange group is introduced. Since,
A powder ion exchange resin having a larger particle size than that of the ion exchange group will be interposed between the cation exchange group and the anion exchange group which face each other. Inhibits direct contact with anion exchange groups and binding resulting from this contact. Here, in order to explain the action and effect of the cation exchanger of the electric desalination apparatus of the present invention in more detail, a cation exchanger is schematically shown in FIG. 3 and described.

In the ion exchanger for an electric desalination apparatus of the present invention shown in FIG. 3, a non-woven fabric is used as a base material, and a graft polymer chain is formed on each fiber by a radiation graft polymerization method. Each fiber has a sulfone group (—SO ₃ ²⁻ ) as an ion exchange group on its graft polymerized chain. Then, a powder ion exchange resin having a tertiary amino group is introduced as the powder ion exchange resin. Here, since the particle size of the powder ion exchange resin is much larger than the particle size of the ion exchange group, the powder ion exchange resin is supported on at least the surface of the ion exchanger. As a result, even when the cation exchanger as the ion exchanger shown in FIG. 3 is used adjacent to the anion exchanger, the ion exchange group of the anion exchanger and the sulfone which is the ion exchange group of the cation exchanger shown in FIG. 3 are used. Since the powder ion exchange resin is supported as a physical steric hindrance between the group and the group, the contact between the ion exchange groups of both ion exchangers is physically reduced. Therefore, the formation of ionic bonds between the ion exchange groups of both ion exchangers is suppressed, and the problem that water dissociation is less likely to occur is solved. As a result, the problem that the operating voltage of the electric desalination apparatus increases due to long-term operation is alleviated.

In order to obtain the desired effects of the present invention, the powder ion exchange resin may be introduced into at least the contact surface with the other ion exchanger, and the ion exchange resin of the present invention can be used. It does not need to be introduced all over. For example, referring to the example shown in FIG. 3, if it is introduced only on the surface which comes into contact with the anion exchanger (whether or not it is the ion exchanger of the present invention), it is not introduced on the other surface. Good.

As is clear from the above, in the present invention, "introducing the powder ion-exchange resin" means that the ionic functional group of the powder ion-exchange resin and the ion-exchange group of the ion-exchanger are present. This means that the powder ion exchange resin is supported or attached on the ion exchange group by ionic bond.

Further, according to the present invention, at least a part of the cation exchange membrane and the anion exchange membrane are alternately arranged between the anode and the cathode to form the desalination chamber and the concentration chamber, There is provided an electric desalination apparatus in which the ion exchanger of the present invention is arranged in the desalination chamber and / or the concentration chamber.

As the ion exchange membrane constituting the electric desalting apparatus, a commercially available ion exchange membrane can be used without limitation. As the cation exchange membrane, for example, NEOSEP can be used.
As the anion exchange membrane such as TA CMX (Tokuyama soda), NEOSEPTA AMX (Tokuyama soda) or the like can be used.

In the electric desalination apparatus of the present invention, a desalting chamber and / or a concentrating chamber, preferably at least a desalting chamber,
The above-mentioned ion exchanger for an electric desalination apparatus of the present invention is arranged. As the arrangement mode of the ion exchanger of the present invention,
Preferred is a mode in which at least one sheet of anion exchanger and / or cation exchanger is arranged facing each other in the desalting chamber and / or the concentrating chamber. In this mode, ions using a fiber-based substrate as the ion exchanger are mentioned. A mode in which only the exchange fiber materials are arranged opposite to each other, a mode in which, in addition to these ion exchange fiber materials as ion exchangers, an ion conductive spacer using a spacer base material is further arranged between the ion exchange fiber materials opposed to each other, etc. is there. In any case, it is preferable from the viewpoint of ion transfer to dispose the anion exchanger on the anion exchange membrane side and the cation exchanger on the cation exchange membrane side of the desalting chamber and / or the concentrating chamber. Further, spacers having no ion conducting function may be further arranged between the ion exchangers arranged to face each other.

The ion exchanger to be placed in the desalting chamber and / or the concentrating chamber may be a single ion exchanger if an ion exchanger for an electric desalination apparatus further containing the powder ion exchange resin of the present invention is used. However, it may be combined with another known ion exchanger. For example, when arranging the ion exchanger using the fibrous base material and the ion exchanger using the spacer base material as described above, at least one ion exchanger among them is the powder ion exchange material of the present invention. Any ion exchanger for an electric desalination device in which a resin is further introduced may be used.

As another ion exchanger which can be used in combination with the ion exchanger for an electric desalination apparatus further incorporating the powder ion exchange resin of the present invention, for example, an ion exchange fiber material and / or an ion can be used. Preferable examples include conductive spacers. Among them, woven cloth,
Form a sheet-shaped substrate using a fibrous material such as non-woven fabric,
An ion-exchange fiber material formed by introducing an ion-exchange group into the sheet-shaped substrate, or an ion-conducting spacer formed by introducing the ion-exchange group into a substrate such as a net is preferably used as another ion-exchanger. be able to. When using such ion-exchange fiber materials and ion-conducting spacers, weak electrolytes such as silica, organic carbon-based (TOC) substances such as alcohol and other organic chemicals are used as compared with the case of using ion-exchange resin beads. There is an advantage that the ions containing the components can be satisfactorily removed.

Further, as another ion exchanger which can be used in combination with the ion exchanger for an electric desalination apparatus of the present invention, a cation exchanger having a sulfone group which is a strongly acidic cation exchange group, and a strong cation exchanger It is preferable to use an anion exchanger having a quaternary ammonium group which is a basic anion exchange group. This is because the water dissociation at the contact portion between the cation exchanger and the anion exchanger, which generate H ⁺ ions and OH ⁻ ions necessary for regeneration of the ion exchanger, is caused by the strongly acidic cation exchange group and the strongly basic anion exchange group. The reason is that the ability to adsorb and remove ions is very high, in addition to the better occurrence between

When the ion conductive spacer is used as described above, the water to be treated tends to disperse and flow while causing a turbulent flow, the spacer and the ion exchanger can be sufficiently adhered, and elution It is preferable that the ion-conducting spacer satisfies the conditions such as less generation of substances and particles and less pressure loss. The shape and size of the ion-conducting spacer can be set as appropriate, and as a material that satisfies all of these conditions satisfactorily, there can be mentioned one using the above-mentioned oblique mesh as a spacer base material as a base material. The processing flow rate can be increased,
The preferred total net thickness with low pressure loss is 0.3-1.5
mm can be mentioned, and it is also possible to use a plurality of very thin spacers within this range as a whole.

When using a plurality of ion-conducting spacers, the anion-conducting spacer is arranged on the side of the anion exchanger using the fibrous base material, and the cation-conducting spacer is arranged on the side of the cation exchanger using the fibrous base material. It is preferable to install it. However, the arrangement of the ion-conducting spacers is not limited to this, and changes depending on the quality of the water to be treated,
Between anion and cation exchangers using fiber-based materials,
A plurality of anion conductive spacers or cation conductive spacers may be arranged. Then, each conductive spacer used in this case may be an ion conductive spacer as the ion exchanger of the present invention into which the powder ion exchange resin of the present invention is further introduced, or a commonly known ion conductive spacer.

As described above, in the electric desalination apparatus of the present invention, various arrangement modes can be adopted for the arrangement of the ion exchanger, that is, the arrangement of the anion exchanger, the cation exchanger and the ion conductive spacer. In this case, It is arbitrary which ion exchanger uses the ion exchanger of the present invention. However, in the electric desalination apparatus of the present invention, an anion type ion exchanger (anion exchange nonwoven fabric,
When the anion-conducting spacer) and the cation-based ion exchanger (cation-exchange nonwoven fabric, cation-conducting spacer) are adjacent to each other, at least one of the adjoining anion-based ion exchanger and cation-based ion exchanger is the present invention. It is preferable to use the ion exchanger of. In particular, it is preferable that either one of the ion-exchange nonwoven fabrics using the nonwoven fabric as the base material is the ion-exchanger of the present invention in which the powder ion-exchanger is further introduced.

In the electric desalination apparatus of the present invention, an anion exchanger using a fiber-based material and a fiber-based material are preferably provided in a desalting chamber and / or a concentrating chamber having a thickness of 2.5 to 5 mm. It is preferable to sandwich a cation exchanger using, and optionally an ion conductive spacer. The thickness of each is
It can be appropriately determined in consideration of the flow rate of treated water, pressure loss, water quality of treated water, voltage and the like.

[0039]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in more detail below with reference to the accompanying drawings. The following description
1 shows a preferred specific example of the electric desalination apparatus according to the present invention, and the present invention is not limited to these descriptions.

FIG. 4 is a schematic view of an electric desalination apparatus according to a preferred embodiment of the present invention. The electric desalination apparatus shown in FIG. 4 has a desalting chamber and a concentrating chamber in which an anion exchange membrane A and a cation exchange membrane C are alternately arranged at least partially between an anode and a cathode. It is an electric desalination device. At least in the desalting chamber, a cation exchange nonwoven fabric, which is an ion exchanger obtained by further introducing the powder ion exchange resin of the present invention, and an anion exchange nonwoven fabric made of an anion exchange fiber material are disposed so as to face each other. In between,
Anion exchange conducting spacers are arranged. In the illustrated embodiment, a set of cells (concentration chamber / desalting chamber /
Although only the concentrating chamber is described, cells in the desalting chamber (concentrating chamber / desalting chamber / concentrating chamber combination) can be obtained by repeating the arrangement of the cation exchange membrane and the anion exchange membrane as necessary.
Are arranged in parallel between the electrodes. In addition, in the arrangement of the ion exchange membranes, there may be a portion in which the ion exchange membranes of the same kind are continuously arranged.

Next, the operation of the electric desalination apparatus according to one embodiment of the present invention shown in FIG. 4 will be described. When a DC voltage is applied between the cathode and the anode and the water to be treated is passed, cations such as Ca ²⁺ , Mg ²⁺ , Na ^{+ in the} water to be treated are ion-exchanged by the cation exchanger in the desalting chamber. Then, under the electric field, the cation exchanger passes through the cation exchange membrane, permeates into the concentration chamber, and is discharged as concentrated water. On the other hand, C in the water to be treated
Anions such as l ⁻ and SO ₄ ²⁻ are ion-exchanged by the anion exchanger in the desalting chamber, pass through the anion exchange membrane from the anion exchanger under an electric field, permeate into the concentrating chamber, and are discharged as concentrated water. To be done.

At this time, as shown in FIG. 2 (a), the cation exchange group (SO ₃ ^{− in} FIG. 2) and the anion exchange group (( CH ₃ ) ₃ N ⁺ ), due to the influence of an electric field generated by the proximity, dissociates water, attracting H ⁺ ions to the cation exchanger side and OH ⁻ ions to the anion exchanger side. As the operation time increases, ionic bonds are formed between the cation exchange group and the anion exchange group which are in close proximity to each other to neutralize the electric charge, so that the hydrolysis does not occur. However, in the present invention, as shown in FIG. 3, the cation-exchange nonwoven fabric has the powder ion-exchange resin introduced on the surface of the ion-exchanger in such a manner as to cause steric hindrance of the ion-exchange group. Between the ion-exchange groups that are separated from each other, an ionic bond is not easily formed and the charge is maintained, so that the dissociation of water continues to proceed. For this reason, an increase in operating voltage due to inhibition of water decomposition after long-term operation is suppressed.

Although FIG. 4 shows a mode in which only the anion exchange spacers are arranged between the ion exchange nonwoven fabrics in the desalting chamber, the anion exchange spacers are placed between the ion exchange nonwoven fabrics, for example, on the anion exchange nonwoven fabric side. The exchange spacer may be arranged on the side of the cation exchange nonwoven fabric.

[0044]

EXAMPLES The present invention will be described in more detail with reference to specific examples.

[0045]

[Manufacturing Example 1] Manufacture of strong acid cation conductive spacers As a base material for ion conductive spacers, thickness 1.2 mm, pitch 3
A polyethylene cross mesh of mm was used. While cooling with dry ice, gamma in a nitrogen atmosphere onto a polyethylene diagonal net.
Irradiated with a line (150 kGy). This γ-irradiated diagonal network,
It is immersed in a mixed aqueous solution of sodium styrenesulfonate and acrylic acid (sodium styrenesulfonate: acrylic acid: water = 25% by weight: 25% by weight) and reacted at 75 ° C. for 3 hours to remove sulfonic acid and carboxyl groups. The obtained graft cross network (graft ratio: 153%) was obtained. This graft cross network was regenerated with hydrochloric acid aqueous solution to give a cation conductive spacer (neutral salt decomposition capacity: 189 meq / m ² ; total exchange capacity: 834 m
eq / m ² ) was obtained.

[0046]

[Production Example 2] Production of strongly basic anion conductive spacer As a base material of the ion conductive spacer, thickness 1.2 mm, pitch 3
A polyethylene cross mesh of mm was used. While cooling with dry ice, gamma in a nitrogen atmosphere onto a polyethylene diagonal net.
Irradiated with a line (150 kGy). Chloromethyl styrene (m-body 70%: p
The irradiated oblique mesh is immersed in a monomer solution of 30% body, product name CMS-AM manufactured by Seimi Chemical Co., Ltd., and the mixture is reacted at 50 ° C. for 5 hours to give a chloromethylstyrene graft oblique network (graft ratio). 90%). The obtained chloromethylstyrene-grafted cross network was quaternized with trimethylamine in an aqueous solution of trimethylamine (10 wt.%) And then regenerated with an aqueous solution of sodium hydroxide to give an anion conductive spacer (neutral salt decomposition capacity: 267 meq / m ² ) was obtained.

[0047]

[Production Example 3] Production of strongly acidic cation exchange nonwoven fabric As a base material, a basis weight of 55 g / m ² composed of a polyethylene (sheath) / polypropylene (core) composite fiber having a fiber diameter of 17 μm, thickness
An electron beam (150 kGy) was irradiated in a nitrogen atmosphere using a 0.35 mm heat-bonded nonwoven fabric.

The heat-bonded nonwoven fabric after the electron beam irradiation treatment was dipped in a 10% methanol solution of glycidyl methacrylate,
The reaction was carried out at 45 ° C for 4 hours. The non-woven fabric after the reaction was immersed in a dimethylformamide solution at 60 ° C. for 5 hours to remove the homopolymer to obtain a glycidyl methacrylate graft non-woven fabric (grafting rate: 131%). This graft non-woven fabric was treated with sodium sulfite: isopropyl alcohol: water = 1: 1:
Immerse in 8 (weight ratio) solution and react at 80 ℃ for 10 hours,
Dried and strongly acidic cation exchange nonwoven fabric (neutral salt decomposition capacity
471 meq / m ² ) was obtained.

[0049]

[Production Example 4] A powder ion exchange resin is further introduced.
Manufacture of strong acid cation exchange nonwoven fabric 10g of powdered anion exchange resin (Dow Chemical; trade name PD-1) with an average particle size of 60μm is regenerated with a 5% sodium hydroxide solution, and the resin concentration is adjusted to 7ppm in an aqueous solution. By suspending, a powder anion exchange resin suspension was prepared.

To the obtained powder anion exchange resin suspension,
The strongly acidic cation exchange nonwoven fabric obtained in Production Example 3 was dipped to absorb 1 L of the powdery anion exchange resin suspension per 1 m ² of the strongly acidic cation exchange nonwoven fabric, and the powder was impregnated so as to be uniformly dispersed. A strongly acidic cation exchange nonwoven fabric was obtained by further introducing an ion exchange resin.

[0051]

[Production Example 5] Production of strongly basic anion-exchange nonwoven fabric As a base material, a basis weight of 55 g / m ² composed of a polyethylene (sheath) / polypropylene (core) composite fiber having a fiber diameter of 17 μm, thickness
An electron beam (150 kGy) was irradiated in a nitrogen atmosphere using a 0.35 mm heat-bonded nonwoven fabric.

Chloromethylstyrene (manufactured by Seimi Chemical Co., Ltd., trade name: CMS-AM) was passed through the activated alumina packed bed to remove the polymerization inhibitor, and deaeration was carried out by aeration with nitrogen. The irradiated non-woven fabric substrate was immersed in the chloromethylstyrene solution after the deoxidation treatment, and reacted at 50 ° C. for 6 hours. Then, the nonwoven fabric was taken out from the chloromethylstyrene solution and immersed in toluene for 3 hours to remove the homopolymer to obtain a chloromethylstyrene graft nonwoven fabric (grafting rate: 161%). The resulting chloromethylstyrene-grafted nonwoven fabric is treated with an aqueous trimethylamine solution (10 wt%)
After being made into a quaternary ammonium salt, it is regenerated with an aqueous solution of sodium hydroxide, and a strongly basic anion exchange nonwoven fabric having a quaternary ammonium group (neutral salt decomposition capacity: 350 meq / m
² ) got

[0053]

Example 1 An electric desalination apparatus (one desalination chamber) having the structure shown in FIG. 4 was assembled. Between the anode (+) and the cathode (-), a cation exchange membrane C (manufactured by Tokuyama: NEOSEPTA CM1) and an anion exchange membrane A (manufactured by Tokuyama: NEOSEPTA AM1) are alternately arranged to form a cation exchange membrane C and an anion. A concentrating chamber, a demineralizing chamber, and a concentrating chamber were formed with the exchange membrane A, an anode chamber was formed between the concentrating chamber and the anode, and a cathode chamber was formed between the concentrating chamber and the cathode. The anode chamber was loaded with four strongly acidic cation-conducting spacers (produced in Production Example 1), and the cathode chamber was loaded with a strongly basic anion-conducting spacer (produced in Production Example 2).
4 sheets were loaded. In the concentration chamber, a strongly basic anion exchange nonwoven fabric (made in Production Example 5) on the anion exchange membrane A side.
Was loaded with one strongly acidic cation exchange nonwoven fabric (produced in Production Example 3) on the cation exchange membrane C side, and a strong basic anion was placed between the strongly basic anion exchange nonwoven fabric and the strongly acidic cation exchange nonwoven fabric. Two conductive spacers (produced in Production Example 2) were loaded. In the desalting chamber, a strongly basic anion exchange nonwoven fabric (produced in Production Example 5) was introduced on the anion exchange membrane A side, and a powdered anion exchange resin was further introduced on the cation exchange membrane C side, which is a strong acid cation exchange nonwoven fabric. One sheet (produced in Production Example 4) was loaded, and two sheets of anion conductive spacers (produced in Production Example 2) were placed between them. The above-mentioned non-woven fabric-based ion exchanger and spacer-based ion exchanger were all cut into a size of 15 cm × 5 cm before use.

A direct current of 0.1 A was applied between both electrodes to reach 0.
2 MΩ RO water (reverse osmosis membrane treated water: silica concentration 0.1 to 0.3 pp
m, water temperature 14 to 20 ° C.) at a flow rate of 5 L / h, ultrapure water of 18 MΩ or more was obtained from the outlet of the desalting chamber. The operating voltage after 100 hours of operation was 53V.

[0055]

Comparative Example 1 The procedure of Example 1 was repeated, except that the cation exchange nonwoven fabric prepared in Production Example 3 was loaded on the cation exchange membrane C side in the desalting chamber. 18 MΩ from the desalting chamber outlet
The above ultrapure water was obtained. Operating voltage after 100 hours of operation is 8
It was 1V.

[0056]

EFFECTS OF THE INVENTION According to the present invention, it is possible to suppress the voltage rise of the ion exchanger for an electric desalination apparatus and the electric desalination apparatus capable of sustaining the dissociation of water even after a long time operation and to operate at a low voltage. A simple electric desalination device can be obtained.

According to the electric desalination apparatus of the present invention, compared with the conventional desalination apparatus, the quality of treated water and the power consumption are remarkably improved, and the apparatus can be operated without using the chemicals for regenerating the ion exchanger. It is possible to suppress an increase in operating voltage and produce ultrapure water only with electric energy.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of an electric desalination apparatus.

FIG. 2 (a) is a schematic diagram showing a mechanism of hydrolyzation generation at a contact portion between a cation exchange group and an anion exchange group. FIG. 2 (b) is a schematic diagram showing a mechanism for suppressing the occurrence of water decomposition at the contact portion between the cation exchange group and the anion exchange group in the electric desalination apparatus after long-time operation.

FIG. 3 is a schematic diagram showing a mechanism of hydrolyzation at a contact portion between a cation exchange group and an anion exchange group in the case of using an ion exchanger into which a powder ion exchange resin according to the present invention is further introduced. is there.

FIG. 4 is a schematic diagram of an electric desalination apparatus according to a preferred embodiment of the present invention.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yohei Takahashi             4-2-1 Honfujisawa, Fujisawa City, Kanagawa Prefecture             Inside the EBARA Research Institute (72) Inventor Takayoshi Kawamoto             11-1 Haneda Asahi-cho, Ota-ku, Tokyo Co., Ltd.             Inside the EBARA CORPORATION (72) Inventor, Nakanishi             11-1 Haneda Asahi-cho, Ota-ku, Tokyo Co., Ltd.             Inside the EBARA CORPORATION F-term (reference) 4D006 GA17 JA30Z JA43Z JA44Z                       KA31 KB11 MA13 MA14 PA01                       PB02                 4D061 DA01 DB13 EA09 EB01 EB04                       EB13 EB19 FA08

Claims (7)

[Claims] 1. An electric desalination apparatus in which a cation exchange membrane and an anion exchange membrane are alternately arranged at least partially between an anode and a cathode to form a desalination chamber and a concentration chamber. In the ion exchanger arranged in the salt chamber and / or the concentration chamber, the ion exchanger has an ion exchange group having a charge of either a cation or an anion, and further has a charge opposite to the ion exchange group. An ion exchanger for an electric desalination apparatus, wherein the ion exchange resin has been introduced. 2. The ion exchanger for an electric desalination device according to claim 1, wherein the ion exchange group is introduced into a side chain of a graft polymer formed on a substrate by a graft polymerization method. An ion exchanger for an electric desalination apparatus, which is characterized in that 3. The ion exchanger for an electric desalination device according to claim 1, wherein the powder ion exchange resin is
An electric desalination apparatus characterized by being introduced into at least the surface of an ion exchanger by bringing an unintroduced ion exchanger into which the powder ion exchange resin has not been introduced into contact with the powder ion exchange resin suspension. Ion exchanger. 4. The ion exchanger for an electric desalination apparatus according to claim 1, wherein the amount of the powder ion exchange resin introduced is an ion of the powder ion exchange resin to be introduced. An ion exchanger for an electric desalination apparatus, which has an exchange capacity of 0.001 to 0.01% of an ion exchange capacity of an ion exchanger into which a powder ion exchange resin is introduced. 5. The ion exchanger for an electric desalination device according to claim 1, wherein the powder ion exchange resin is a carboxyl group, a sulfone group, a quaternary ammonium group, or 3 An ion exchanger for an electric desalting apparatus, which comprises a primary amino group, a secondary amino group or a primary amino group. 6. The ion exchanger for an electric desalination apparatus according to claim 2, wherein the graft polymer side chain is formed by using a radiation graft polymerization method. An ion exchanger for an electric desalination apparatus, which is characterized in that 7. A desalting chamber and a concentrating chamber are formed by alternately arranging at least a part of a cation exchange membrane and an anion exchange membrane between an anode and a cathode, and the desalting chamber and / or the concentrating chamber. An electric desalination apparatus, wherein the ion exchanger for an electric deionization apparatus according to any one of claims 1 to 6 is arranged in a chamber.