JP2006346543A - Apparatus and method for treating water - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus and a method for treating water, in each of which treated water in which concentrations of salt and ions are decreased sufficiently, is obtained economically. <P>SOLUTION: The apparatus for treating water comprises a desalting means and an ion adsorbing means in which a porous molding is used as an adsorbent. The porous molding comprises an organic polymeric resin and an inorganic ion adsorbent and has a communicative pore opened to the outside surface and a void in a fibril forming the communicative pore. At least a part of the void is opened to the surface of the fibril. The inorganic ion adsorbent is deposited on the outside surface of the fibril and on the surface of the internal void. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a water treatment apparatus and a water treatment method for reducing and removing salts and ions contained in various waters such as seawater, river water, lake water, ground water, industrial waste water, and tap water.

As a treatment for removing salts and ions contained in water, a treatment using a reverse osmosis membrane device, an electrodeionization device, a distillation device, an ion exchange device using an ion exchange resin or the like is known. Yes.
However, due to the relationship between the characteristics of each treatment method and the concentration of salts and ions contained in the raw water to be treated, certain salts and ions often cannot be removed to a desired level.
For example, treated water (fresh water) obtained by treating seawater with a reverse osmosis membrane device has water quality that almost meets the WHO water quality guideline values, but for boron only the WHO recommended value (0.5 ppm) or less It is difficult to make.

Therefore, JP-A-10-85743 (Patent Document 1) treats seawater in combination with a reverse osmosis membrane apparatus and an ion exchange apparatus using a boron-selective ion exchange resin, and recommends a boron concentration of WHO. Processing to make it below the value has been proposed.
However, since the boron selective ion exchange resin does not have a very large boron adsorption capacity, there are problems in terms of economy, such as an increase in the size of the ion exchange device, and an increase in the frequency of regeneration and exchange of the ion exchange resin. is there.

In addition, even when ultrapure water is produced by treating tap water with an electrodeionization apparatus, depending on the type of raw water, boron is not sufficiently removed, and the water quality is insufficient as ultrapure water. May be obtained. In such a case, water treated by an electrodeionization apparatus is further treated by using an ion exchange apparatus using a boron-selective ion exchange resin (JP-A-8-89956). (Refer to Patent Document 2)) There are also problems in terms of economy, such as an increase in the size of the ion exchange device and an increase in the frequency of regeneration and replacement of the ion exchange resin.
Japanese Patent Laid-Open No. 10-85743 JP-A-8-89956

  The present invention solves the problems of the conventional water treatment apparatus and water treatment method described above, and provides a water treatment apparatus and a water treatment method for economically obtaining water from which salt and ion concentrations are sufficiently removed. For the purpose.

  As a result of intensive studies to solve the above problems, the present inventors have found that a porous molded body having a specific structure exhibits extremely high adsorption performance for various ions contained in water. It was. And, the treated water from which various salts and ions have been sufficiently removed by combining the ion-adsorbing treatment for adsorbing and removing ions contained in the water by bringing this porous molded body into contact with water, and the desalting treatment. The present invention has been completed by finding that an apparatus and a method capable of economically producing can be obtained.

That is, the present invention is as follows.
1. A water treatment apparatus comprising a desalination treatment means and an ion adsorption treatment means using a porous molded article as an adsorbent, wherein the porous molded article comprises an organic polymer resin and an inorganic ion adsorbent. A porous molded body having a communication hole opened on the surface, having a void inside the fibril forming the communication hole, and at least a part of the void is open on the surface of the fibril, the fibril A water treatment apparatus, wherein an inorganic ion adsorbent is supported on the outer surface and the inner void surface.
2. The communication hole has a maximum pore diameter layer in the vicinity of the surface of the molded body. The water treatment apparatus as described.
3. The porous molded body has an average particle diameter of 100 to 2500 μm and is substantially spherical. Or 2. The water treatment apparatus as described in.
4). The porous molded body contains at least one selected from the group consisting of ethylene vinyl alcohol copolymer (EVOH), polyacrylonitrile (PAN), polysulfone (PS), and polyvinylidene fluoride (PVDF) as an organic polymer resin. 1. A porous molded body comprising: ~ 3. The water treatment apparatus as described in any one of.

5. The inorganic ion adsorbent contains at least one metal oxide represented by the following formula (I): ~ 4. The water treatment apparatus as described in any one of.
_{MN x O n · mH 2 O} (I)
(Wherein x is 0 to 3, n is 1 to 4, m is 0 to 6, and M and N are Ti, Zr, Sn, Sc, Y, La, Ce, Pr, Nd, Sm, Eu. Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Al, Si, Cr, Co, Ga, Fe, Mn, Ni, V, Ge, Nb and Ta are metal elements selected from the group Are different from each other.)

6). 4. The metal oxide represented by the formula (I) is one or a mixture selected from any of the following groups (a) to (c): The water treatment apparatus as described in.
(A) hydrated titanium oxide, hydrated zirconium oxide, hydrated tin oxide, hydrated cerium oxide, hydrated lanthanum oxide, and hydrated yttrium oxide (b) consisting of titanium, zirconium, tin, cerium, lanthanum, and yttrium A composite metal oxide of a metal element selected from the group and a metal element selected from the group consisting of aluminum, silicon, and iron (c) activated alumina

7). 1. The ion to be adsorbed by the ion adsorption treatment means is phosphorus, boron, fluorine and / or arsenic. ~ 6. The water treatment apparatus as described in any one of.
8). A water treatment method comprising, in this order, a desalination treatment step and an ion adsorption treatment step using a porous molded article as an adsorbent, wherein the porous molded article comprises an organic polymer resin and an inorganic ion adsorbent. A porous molded body having a communication hole that opens to the outer surface, and has a void inside the fibril forming the communication hole, and at least a part of the void is open on the surface of the fibril. A water treatment method characterized in that an inorganic ion adsorbent is supported on the outer surface of the fibril and the surface of the internal void.

  According to the present invention, water with an extremely high water quality from which salts and ions have been sufficiently removed can be produced economically.

Hereinafter, the present invention will be described in detail.
The desalting means in the present invention is a conventionally known desalting means using a reverse osmosis membrane device, an electrodeionization device, a distillation device, an ion exchange device using an ion exchange resin, or the like. This processing means may be carried out using each device alone, or may be carried out by combining multiple devices of the same type in multiple stages, such as providing reverse osmosis membrane devices in multiple stages in series. Moreover, you may implement combining a several kind of apparatus. When processing by combining a plurality of devices, they can be combined in any order.

  The ion adsorption treatment means in the present invention is a treatment for adsorbing and removing ions contained in the water by using the molded article having ion adsorption ability as an adsorbent and bringing the molded article into contact with water. In the ion adsorption treatment means constituting the water treatment apparatus of the present invention, it is necessary to use a porous molded body having a specific structure as an adsorbent.

The porous molded body will be described below.
The porous molded body used as an adsorbent for the ion adsorption treatment constituting the water treatment apparatus of the present invention is obtained by dissolving an organic polymer resin in an appropriate good solvent and further soluble in the good solvent and the organic polymer resin. It is obtained by suspending the inorganic ion adsorbent powder, which is an adsorption substrate, in a polymer solution in which a water-soluble polymer having an affinity for is dissolved and mixing, and forming a poor solvent as a coagulation bath. It has a porous structure with Further, there is no skin layer on the outer surface, and the surface has excellent openability. Further, there is a void inside the fibril forming the communication hole, and at least a part of the void is opened on the fibril surface.

The outer surface aperture ratio in the present invention refers to the ratio of the sum of the aperture areas of all the holes in the area of the field of view when the surface is observed with a scanning electron microscope. In the present invention, the surface of the molded body was observed at a magnification of 10,000 to actually measure the outer surface opening ratio.
The range of the surface opening ratio is preferably 10 to 90%, and particularly preferably 15 to 80%. If it is less than 10%, the diffusion rate of ions to be adsorbed inside the molded product tends to be slow, whereas if it exceeds 90%, the strength of the molded product is insufficient, and it is difficult to realize a molded product having excellent chemical strength.

  The outer surface opening diameter referred to in the present invention is determined by observing the surface with a scanning electron microscope. When the hole is circular, the diameter is used. When the hole is not circular, the equivalent circle diameter of a circle having the same area is used. A preferable range of the surface opening diameter is O.005 μm to 100 μm, and particularly preferably O.01 μm to 50 μm. If it is less than O.005 μm, the diffusion rate of ions to be adsorbed into the molded body tends to be slow, whereas if it exceeds 100 μm, the strength of the molded body tends to be insufficient.

The porous molded body used in the present invention has voids inside the fibrils forming the communicating holes, and at least a part of the voids are opened on the surface of the fibrils. The inorganic ion adsorbent is supported on the outer surface of the fibril and the void surface inside the fibril. Since the fibril itself is also porous, an inorganic ion adsorbent that is an adsorption substrate embedded inside can also come into contact with ions to be adsorbed, and can effectively function as an adsorbent.
Since the porous molded body used in the present invention is porous even in such a portion where the adsorption substrate is supported, the adsorption substrate is less likely to be clogged with fine adsorption sites of the adsorption substrate. Can be used.

Here, the fibril means a fibrous structure formed of an organic polymer resin and forming a three-dimensional continuous network structure on the outer surface and inside of the molded body. The void inside the fibril and the opening of the fibril surface are determined by observing the cut section of the molded body with a scanning electron microscope. It is observed that there are voids in the cross-section of the fibril and that the surface of the fibril is open. Furthermore, it is observed that the inorganic ion adsorbent powder is supported on the outer surface of the fibril and the inner void surface.
The thickness of the fibril is preferably O.01 μm to 50 μm.
The pore diameter on the fibril surface is preferably O.001 μm to 5 μm.

The mechanism by which the structure of the porous molded body used in the present invention is developed will be considered.
In general, a method of forming a porous body by immersing a mixture of a polymer and a good solvent of the polymer in a poor solvent and causing the polymer to gel by solvent exchange is called a wet phase separation method. In these processes, the proportion of the good solvent decreases, and microphase separation occurs accordingly, polymer spheres form, grow, entangle and form fibrils, and the fibril gaps become communication holes.
Further, the determination (solidification) of the compact structure proceeds sequentially from the outer surface to the inner part due to the diffusion of the poor solvent into the inner part. In this method, a dense layer called a skin layer is generally formed on the surface of the molded body.

On the other hand, in the porous molded body used in the present invention, by adding a water-soluble polymer described later, the water-soluble polymer is dispersed and intervened during the entanglement of the polymer in the process of phase separation. The pores communicate with each other, the inside of the fibril becomes porous, and the fibril surface also opens. Further, it is considered that a hole is formed on the outer surface of the molded body, and a molded body having no skin layer is obtained.
In addition, the water-soluble polymer partially dissolves in the poor solvent during the phase separation process, but a part remains in the fibril while being entangled with the molecular chain of the organic polymer resin. The remaining water-soluble polymer is considered to coat the gap between the adsorption substrate and the fibril which are inorganic ion adsorbents, and does not block the active site of the adsorption substrate. Therefore, the porous molded body used as the adsorbent in the present invention can use almost all of the adsorption capacity of the supported inorganic ion adsorbent and has high efficiency. Therefore, it has extremely high adsorption performance.

Furthermore, since the water-soluble polymer partially extends its molecular chain from the surface of the fibril as if it were a beard, the surface of the fibril is kept hydrophilic, and an antifouling effect from hydrophobic adsorption can be expected.
In the porous molded body used in the present invention, the communicating holes preferably have a maximum pore diameter layer near the surface of the molded body. Here, the maximum pore diameter layer means the largest portion in the pore diameter distribution of the communication holes extending from the surface of the molded body to the inside. In the case where there is a large circular or oval (finger-like) void called a void, the layer in which the void exists is called the maximum pore diameter layer.
The vicinity of the surface means the inner side up to 25% of the cleaved diameter of the molded body from the outer surface toward the center.

By having the maximum pore diameter layer in the vicinity of the surface of the molded body, it has the effect of accelerating the diffusion of ions to be adsorbed into the interior. Therefore, adsorption object ions can be quickly taken into the molded body and removed from the treated water.
The positions of the maximum pore diameter and the maximum pore diameter layer are determined by observing the surface and the cut surface of the molded body with a scanning electron microscope.
As the hole diameter, when the hole is circular, the diameter thereof is used. When the hole is not circular, the equivalent circle diameter of a circle having the same area is used.
The form of the molded body can take any form such as a particulate form, a thread form, a sheet form, a hollow fiber form, a cylindrical form, and a hollow cylindrical form.

The method for forming the particulate molded body is not particularly limited, and examples thereof include a method in which a polymer solution is sprayed from a fluid nozzle and solidified in a coagulation bath.
In particular, the following rotating nozzle method is particularly preferable in that particles having a uniform particle size distribution can be obtained. The rotating nozzle method is a method in which a polymer solution (an organic polymer resin, a good solvent for the organic polymer resin, an inorganic ion adsorbent, a water This is a method of forming droplets by scattering a mixed slurry of a conductive polymer).
The diameter of the nozzle is preferably in the range of 0.1 mm to 10 mm, and more preferably in the range of 0.1 mm to 5 mm. If it is smaller than O.1 mm, the droplets tend not to scatter, and if it exceeds 10 mm, the particle size distribution tends to be wide.

Centrifugal force is expressed in terms of centrifugal acceleration, preferably in the range of 5 to 1500 G, and more preferably in the range of 10 to 1000 G. More preferably, it is the range of 10-800G. When the centrifugal acceleration is less than 5G, the formation and scattering of droplets tend to be difficult, and when it exceeds 1000G, the polymer liquid is discharged in the form of a thread, and the particle size distribution tends to be widened.
The thread-like and sheet-like molded bodies can be obtained by extruding a polymer solution from a spinneret and a die having a corresponding shape and coagulating in a poor solvent. Moreover, a hollow fiber shaped molded product can be similarly molded by using a spinning nozzle composed of an annular orifice. When extruding the polymer stock solution from the spinning nozzle, the cylindrical and hollow cylindrical molded bodies may be solidified in a poor solvent while being cut, or may be solidified into a filament and then cut later.

  In particular, when the molded body is used as an adsorbent in the water treatment field, the particle shape is reduced in terms of pressure loss, effectiveness of the contact area and ease of handling when packed in a column or the like and passed through. Spherical particles (not only true spheres but also oval spheres) are particularly preferable.

  The average particle diameter of the spherical molded body as referred to in the present invention is a mode diameter (most frequent particle diameter) of a sphere equivalent diameter obtained from an angular distribution of scattered light intensity of diffraction by laser light, assuming that the particles are spherical. . A preferable range of the average particle diameter is 100 to 2500 μm, particularly 200 to 2000 μm. If the average particle size is smaller than 100μm, pressure loss tends to increase when packed in a column or tank, and if the average particle size is larger than 2500μm, the surface area when packed in a column or tank is decreased, resulting in a processing efficiency. Is prone to decline.

The porosity Pr (%) of the molded product as used in the present invention refers to the weight W1 (g) of the molded product when it contains water, the weight W0 (g) after drying, and the specific gravity of the molded product as ρ. A value expressed by an expression.
Pr = (W1-WO) / (W1-WO + W0 / ρ) × 100
The wet weight may be determined by spreading a molded product sufficiently wet with water on dry filter paper and taking excess water before measuring the wet weight. Drying may be performed under vacuum at room temperature in order to eliminate moisture. The specific gravity of the molded body can be easily measured using a specific gravity bottle.
A preferable range of the porosity Pr (%) is 50% to 90%, and particularly preferably 60 to 85%. If it is less than 50%, the contact frequency between the substance to be adsorbed and the inorganic ion adsorbent as the adsorption substrate tends to be insufficient. If it exceeds 90%, the strength of the molded product tends to be insufficient.

The supported amount of the inorganic ion adsorbent in the molded product in the present invention refers to a value represented by the following formula when the weight Wd (g) when the molded product is dried and the weight Wa (g) of ash.
Load (%) = Wa / Wd × 100
Here, the ash content is the residue when the molded product of the present invention is baked at 800 ° C. for 2 hours.
A preferable loading range is 30 to 95%, more preferably 40 to 90%, and particularly preferably 65 to 90%. If it is less than 30%, the contact frequency between the ions to be adsorbed and the inorganic ion adsorbent as the adsorption substrate tends to be insufficient, and if it exceeds 95%, the strength of the molded product tends to be insufficient.
The method for producing a porous molded body used in the present invention is different from the conventional attaching method in that an adsorbing substrate and an organic polymer resin are kneaded and molded, so that a molded body having a high load and a high strength is obtained. be able to.

The specific surface area of the molded product referred to in the present invention is defined by the following formula.
Specific surface area (m ² / cm ³ ) = S _BET × Bulk specific gravity (g / cm ³ )
Here, S _BET is a specific surface area (m ² / g) per unit weight of the molded body.
The specific surface area is measured using the BET method after vacuum drying the molded body at room temperature.
The bulk specific gravity is measured by measuring the apparent volume of a short shaped product such as a particle, a column, or a hollow column using a wet compact and a graduated cylinder. Then, it vacuum-drys at room temperature and calculates | requires a weight.

For a long fiber-like, hollow fiber-like, or sheet-like shape, the cross-sectional area and length when wet are measured, and the volume is calculated from the product of both. Then, it vacuum-drys at room temperature and calculates | requires a weight.
The preferred range of the specific surface area is ^{5m 2 / cm 3 ~500m 2 /} cm 3. If it is less than 5 m ² / cm ³ , the supported amount and adsorption performance of the adsorption substrate tend to be insufficient, and if it exceeds 500 m ² / cm ³ , the strength of the molded product tends to be insufficient.
In general, the adsorption performance (adsorption capacity) of an inorganic ion adsorbent that is an adsorption substrate is often proportional to the specific surface area. If the surface area per unit volume is small, the adsorption capacity and adsorption performance when packed in a column or tank are small, making it difficult to achieve high-speed processing.

The porous molded body used in the present invention has a three-dimensional network structure that is porous and intricately intertwined with fibrils. Furthermore, since the fibril itself has voids, it has a feature that the surface area is large. Since this has an adsorption substrate (inorganic ion adsorbent) having a larger specific surface area, the surface area per unit volume is also increased.
Since the porous molded body having the specific structure described above has extremely high adsorption performance with respect to various ions, ion adsorption treatment using this porous molded body as an adsorbent is performed as a desalting treatment. The water treatment apparatus and water treatment method of the present invention configured in combination with water can economically produce water with a very high water quality level from which salts and ions are sufficiently removed.

The porous molded body used in the present invention has a high opening property on the surface of the molded body, the communication holes are developed in a three-dimensional network inside the molded body, and the fibrils forming the communication holes are also porous. Therefore, the contact efficiency is high.
In addition, the porous molded body can adsorb anions again by contacting the alkaline aqueous solution to desorb the adsorbed anions and then treating the adsorbent with an acidic aqueous solution (re-applying). Use). In particular, since this porous molded body is extremely excellent in durability against repeated use, it is possible to further improve the economics of treatment by the water treatment apparatus of the present invention by repeating reuse. In addition, there is an effect that waste can be reduced.

Next, the manufacturing method of the porous molded object used as an adsorbent by this invention is demonstrated.
This method for producing a porous molded body is characterized in that an organic polymer resin, its good solvent, an inorganic ion adsorbent, and a water-soluble polymer are mixed and then molded and solidified in a poor solvent.
The organic polymer resin used for production is not particularly limited, but is preferably one that can be made porous by wet phase separation. For example, polysulfone polymer, polyvinylidene fluoride polymer, polyvinylidene chloride polymer, acrylonitrile polymer, polymethyl methacrylate polymer, polyamide polymer, polyimide polymer, cellulose polymer, ethylene vinyl alcohol copolymer polymer, etc. There are many types.

In particular, ethylene vinyl alcohol copolymer (EVOH), polyacrylonitrile (PAN), polysulfone (PS), and polyvinylidene fluoride (PVDF) are preferable from the viewpoint of non-swelling property and biodegradability in water and ease of production. Furthermore, an ethylene vinyl alcohol copolymer (EVOH) is preferable because it has both hydrophilicity and chemical resistance.
The good solvent used in the production may be any solvent as long as it dissolves both the organic polymer resin and the water-soluble polymer. For example, dimethyl sulfoxide (DMSO), N-methyl-2-pyrrolidone (NMP), dimethylacetamide (DMAC), dimethylformamide (DMF) and the like. These good solvents may be used alone or as a mixed solvent.

The content of the organic polymer resin in the good solvent is not particularly limited, but is preferably 5 to 40% by weight, and more preferably 7 to 30% by weight. If it is less than 5% by weight, it is difficult to obtain a strong molded product. When it exceeds 40% by weight, it is difficult to obtain a porous molded body having a high porosity.
The water-soluble polymer used for production is not particularly limited as long as it is compatible with the organic polymer resin.
Examples of natural polymers include guar gum, locust bean gum, carrageenan, gum arabic, tragacanth, pectin, starch, dextrin, gelatin, casein, collagen and the like.

Examples of the semisynthetic polymer include methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, ethyl hydroxyethyl cellulose, carboxymethyl starch, and methyl starch.
Furthermore, examples of the synthetic polymer include polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl methyl ether, carboxyvinyl polymer, sodium polyacrylate, and polyethylene glycols such as tetraethylene glycol and triethylene glycol.
Among these water-soluble polymers, a synthetic polymer is preferable in that it has biodegradability resistance.

In particular, polyvinyl pyrrolidone is used as the water-soluble polymer because it has a high effect of developing a structure having voids inside the fibrils forming the communicating holes, such as the porous molded body used as the adsorbent in the present invention. Particularly preferred.
The weight average molecular weight of polyvinylpyrrolidone is preferably in the range of 2,000 to 2,000,000, more preferably in the range of 2,000 to 1,000,000, and still more preferably in the range of 2,000 to 100,000. If the weight average molecular weight is less than 2,000, the effect of developing a structure having voids inside the fibril tends to be low. If the weight average molecular weight exceeds 2,000,000, the viscosity at the time of molding increases, and molding is difficult. It tends to be difficult.

The content of the water-soluble polymer in the porous molded product referred to in the present invention is defined as Wd (g) when the molded product is dried and Ws (g) as the weight of the water-soluble polymer extracted from the molded product. The value expressed by the following formula.
Content (%) = Ws / Wd × 100
The content of the water-soluble polymer depends on the type and molecular weight of the water-soluble polymer, but is preferably 0.001 to 10%, and more preferably 0.01 to 1%. If it is less than 0.001%, the effect is not necessarily sufficient to open the surface of the molded body, and if it exceeds 10%, the polymer concentration becomes relatively thin and the strength may not be sufficient.

  Here, the weight Ws of the water-soluble polymer in the molded body is measured as follows. First, after the dried molded body is pulverized in a mortar or the like, the water-soluble polymer is extracted from the pulverized product using a good solvent for the water-soluble polymer, and then the extract is evaporated to dryness, The weight of the conducting polymer is determined. Furthermore, identification of the extracted evaporated and dried product and confirmation of the presence or absence of the water-soluble polymer remaining in the fibril and not extracted can be measured by infrared absorption spectrum (IR) or the like. Furthermore, when there is a water-soluble polymer that remains in the fibrils and is not extracted, the porous molded body of the present invention is dissolved in a good solvent for both the organic polymer resin and the water-soluble polymer, and then the inorganic ions are dissolved. A liquid obtained by removing the adsorbent by filtration can be prepared, and then the liquid can be analyzed using GPC or the like to quantify the content of the water-soluble polymer.

The content of the water-soluble polymer can be appropriately adjusted depending on the molecular weight of the water-soluble polymer and the combination of the organic polymer resin and the good solvent. For example, when a water-soluble polymer having a high molecular weight is used, the entanglement of the molecular chain with the organic polymer resin becomes strong, and it becomes difficult to move to the poor solvent side during molding, and the content can be increased.
The inorganic ion adsorbent used in the porous molded body used as the adsorbent in the present invention refers to an inorganic substance exhibiting ion adsorbing ability.

The inorganic ion adsorbent used in the present invention refers to an inorganic substance exhibiting an ion adsorption phenomenon.
For example, natural products include zeolite, montmorillonite, and various mineral substances, and synthetic products include metal oxides. The former is represented by aluminosilicate kaolin mineral with a single layer lattice, bilayer latticed muscovite, sea chlorite, kanuma earth, pyrophyllite, talc, three-dimensional framework feldspar, zeolite and the like. The latter mainly includes polyvalent metal salts, metal oxides, insoluble heteropolyacid salts, insoluble hexacyanoferrates, and the like.

Examples of the polyvalent metal salt include hydrotalcite compounds represented by the following formula (II).
M ²⁺ _(1-X) M ³⁺ _x (OH ⁻ ) _{(2 + xy)} (A ⁿ⁻ ) y / n (II)
[ ^Wherein M ²⁺ represents at least one divalent metal ion selected from the group consisting of Mg ²⁺ , Ni ²⁺ , Zn ²⁺ , Fe ²⁺ , Ca ²⁺ and Cu ²⁺ ; ³⁺ represents at least one trivalent metal ion selected from the group consisting of Al ³⁺ and Fe ^3+, a ^n-represents an n-valent anion, be 0.1 ≦ x ≦ 0.5 0.1 ≦ y ≦ 0.5, and n is 1 or 2. ]
The metal oxide can be represented by the following formula (I).
_{MN x O n · mH 2 O} (I)
(Wherein x is 0 to 3, n is 1 to 4, m is 0 to 6, and M and N are Ti, Zr, Sn, Sc, Y, La, Ce, Pr, Nd, Sm, Eu. Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Al, Si, Cr, Co, Ga, Fe, Mn, Ni, V, Ge, Nb and Ta are metal elements selected from the group Are different from each other.)

The metal oxide referred to in the present invention may be an unhydrated (non-hydrated) metal oxide in which m in the formula (I) can be represented by 0, or a hydrate (m can be represented by a numerical value other than 0). It may be a hydrous metal oxide.
The metal oxide in the case where x in formula (I) is a numerical value other than 0 is such that each contained metal element has regularity and is uniformly distributed throughout the oxide, for example, a perovskite structure, spinel It forms a structure and the like, and is contained in metal oxides such as nickel ferrite (NiFe ₂ O ₄ ) and zirconium hydrous ferrite (Zr · Fe ₂ O ₄ · mH ₂ O m is 0.5 to 6). It is a complex metal oxide represented by a chemical formula in which the composition ratio of each metal element is fixed.

The inorganic ion adsorbent supported on the porous molded body of the present invention is represented by the above formula (I) and has the following (a) to (a) to It is preferable that it is 1 type of the metal oxide chosen from the group in any one of (c), or those mixtures.
(A) hydrated titanium oxide, hydrated zirconium oxide, hydrated tin oxide, hydrated cerium oxide, hydrated lanthanum oxide, and hydrated yttrium oxide (b) consisting of titanium, zirconium, tin, cerium, lanthanum, and yttrium A composite metal oxide of a metal element selected from the group and a metal element selected from the group consisting of aluminum, silicon, and iron (c) activated alumina In addition, activated alumina loaded with aluminum sulfate, activated carbon loaded with aluminum sulfate, and the like are also preferred.

The metal oxide represented by the formula (I) used in the present invention may be a solid solution of metal elements other than M and N. For example, the hydrated zirconium oxide represented by the formula ZrO ₂ · mH ₂ O according to the formula (I) may be hydrated zirconium oxide in which iron is dissolved.
The inorganic ion adsorbent used in the present invention may contain a plurality of metal oxides represented by the formula (I). There are no particular restrictions on the distribution state of each metal oxide, but in order to obtain an inorganic ion adsorbent that has better cost performance by effectively utilizing the characteristics of each metal oxide, the surroundings of a specific metal oxide Is preferably a mixed structure covered with another metal oxide. An example of such a structure is a structure in which hydrated zirconium oxide covers the periphery of triiron tetroxide.

In addition, since the metal oxide referred to in the present invention includes a metal oxide in which other elements are dissolved, the hydrated zirconium oxide in which iron is dissolved in the surrounding area of triiron tetroxide in which zirconium is in solid solution. A covered structure can also be exemplified as a preferred example.
In the above example, hydrated zirconium oxide has high adsorption performance for ions such as phosphorus, boron, fluorine, arsenic and durability for repeated use, but is expensive. On the other hand, triiron tetroxide has a low adsorption performance for ions such as phosphorus, boron, fluorine, and arsenic and a durability performance for repeated use, but is very inexpensive.

  Therefore, when the structure of iron tetroxide is covered with hydrated zirconium oxide, the surface of the inorganic ion adsorbent that is involved in the adsorption of ions becomes hydrated zirconium oxide with high adsorption performance and durability. Since the inside which does not participate in adsorption becomes inexpensive iron trioxide, a porous molded body which can be used as an adsorbent having high adsorption performance, high durability performance and low cost, that is, excellent in cost performance is obtained.

  From the viewpoint of obtaining an adsorbent with excellent cost performance for adsorption and removal of ions harmful to the environment and health of phosphorus, boron, fluorine and arsenic, the inorganic ion adsorbent used in the present invention is represented by the formula (I) In the formula (I), at least one of M and N is a metal element selected from the group consisting of aluminum, silicon, and iron. At least one of M and N in the formula (I) is titanium, zirconium, tin, or cerium. , Lanthanum, and yttrium, and a metal element selected from the group consisting of lanthanum and yttrium is preferable.

  In this case, the content ratio of the metal element selected from the group consisting of aluminum, silicon, and iron in the inorganic ion adsorbent is a metal element selected from the group consisting of aluminum, silicon, and iron, and titanium, zirconium, tin, cerium, The total number of moles of the metal element selected from the group consisting of lanthanum and yttrium is T, the number of moles of the metal element selected from the group consisting of aluminum, silicon, and iron is F, and F / T (molar ratio) is 0.00. The range is preferably from 01 to 0.95, more preferably from 0.1 to 0.90, still more preferably from 0.2 to 0.85, and from 0.3 to 0.80. It is particularly preferred that When the value of F / T (molar ratio) is excessively increased, the adsorption performance and durability performance tend to be lowered.

Also, depending on the metal, there are a plurality of forms of metal oxides with different oxidation numbers of the metal elements, but the form is not limited as long as it can exist stably in the inorganic ion adsorbent. For example, in the case of an iron oxide, hydrated ferric oxide (FeO _1.5 · mH ₂ O) or hydrated iron trioxide (FeO _1.33 · mH ₂ O) is preferred.
In addition, the inorganic ion adsorbent of the present invention may contain an impurity element mixed due to its production method or the like within a range not departing from the achievement of the object of the present invention. Possible impurity elements to be mixed include nitrogen (nitrate, nitrite, ammonium), sodium, magnesium, sulfur, chlorine, potassium, calcium, copper, zinc, bromine, barium, hafnium, and the like.

In addition, since the specific surface area of the inorganic ion adsorbent affects the adsorption performance and durability, the specific surface area is preferably within a certain range. Specifically, it is preferable that a BET specific surface area determined by nitrogen adsorption method is 20~1000m ² / g, more preferably 30~800m ² / g, it is 50 to 600 m ² / g More preferably, it is 60-500 m < ² > / g. If the BET specific surface area is too small, the adsorption performance decreases, and if it is too large, the solubility in acid and alkali alkali increases, and as a result, the durability performance against repeated use decreases.

  Although the manufacturing method of the metal oxide represented by the formula (I) used in the present invention is not particularly limited, for example, it is manufactured by the following method. A precipitate obtained by adding an alkaline solution to an aqueous salt solution of metal hydrochloride, sulfate, nitrate or the like is filtered, washed and dried. The drying is performed by air drying or at about 150 ° C. or less, preferably about 90 ° C. or less for about 1 to 20 hours.

  Next, around at least one of M and N in the formula (I) around the metal oxide in which at least one of M and N in the formula (I) is a metal element selected from the group consisting of aluminum, silicon and iron As a method for producing an inorganic ion adsorbent having a structure covered with a metal oxide that is a metal element selected from the group consisting of titanium, zirconium, tin, cerium, lanthanum, and yttrium, A case where an inorganic ion adsorbent having a structure in which zirconium oxide is covered is manufactured will be described.

  First, salts obtained by mixing a salt such as zirconium chloride, nitrate or sulfate with a salt such as iron chloride, nitrate or sulfate so that the above-mentioned F / T (molar ratio) is a desired value. Make an aqueous solution. Thereafter, an aqueous alkaline solution is added to adjust the pH to preferably 8 to 9.5, more preferably 8.5 to 9 to generate a precipitate. Thereafter, the temperature of the aqueous solution is set to 50 ° C., and air is blown in while maintaining the pH at preferably 8 to 9.5, more preferably 8.5 to 9, until the ferrous ions cannot be detected in the liquid phase. Process. The resulting precipitate is filtered off, washed with water and dried. The drying is performed by air drying or preferably at about 150 ° C. or less, more preferably at about 90 ° C. or less for about 1 to 20 hours. The moisture content after drying is preferably in the range of about 6 to 30% by weight.

Zirconium oxychloride (ZrOC1 ₂ ), zirconium tetrachloride (ZrC1 ₄ ), zirconium nitrate (Zr (NO ₃ ) ₄ ), zirconium sulfate (Zr (SO ₄ ) ₂ ) Etc. These may be hydrated salts such as Zr (SO ₄ ) ₂ .4H ₂ O. These metal salts are usually used in the form of a solution of about 0.05 to 2.O moles per liter.
Examples of the iron salt used in the above-described production method include ferrous salts such as ferrous sulfate (FeSO ₄ ), ferrous nitrate (Fe (NO ₃ ) ₂ ), and ferrous chloride (FeC1 ₂ ). Can be mentioned. These may also be hydrated salts such as FeSO ₄ .7H ₂ O. These ferrous salts are usually added as solids, but may be added in the form of a solution.

Examples of the alkali include sodium hydroxide, potassium hydroxide, calcium hydroxide, ammonia, sodium carbonate and the like. These are preferably used in an aqueous solution of about 5-20% by weight.
When the oxidizing gas is blown, the time varies depending on the kind of the oxidizing gas, but is usually about 1 to 10 hours. As the oxidizing agent, for example, hydrogen peroxide, sodium hypochlorite, potassium hypochlorite and the like are used.

The inorganic ion adsorbent of the present invention is preferably as fine as possible, and its particle size is preferably from 0.01 to 100 μm, more preferably from 0.01 to 50 μm, and even more preferably from 0.01 to 30 μm. It is a range.
If the particle size is smaller than 0.01 μm, the viscosity of the slurry at the time of production tends to increase and it tends to be difficult to mold. If it exceeds 100 μm, the specific surface area tends to be small, and the adsorption performance tends to be lowered.
The particle diameter here refers to the particle diameter of both the primary particles and the secondary particles in which the primary particles are aggregated or a mixture. The particle diameter of the inorganic ion adsorbent of the present invention is a sphere equivalent diameter (most frequent particle diameter) obtained from the angular distribution of scattered light intensity of diffraction by laser light.

  In the production of the porous molded body used as the adsorbent in the present invention, examples of the poor solvent include water, alcohols such as methanol and ethanol, industrial carbons, aliphatic carbonization such as n-hexane and n-heptane. A liquid that does not dissolve organic polymer resins such as hydrogen is used, but water is preferably used. It is also possible to control the coagulation rate by adding a little good solvent of the organic polymer resin in the poor solvent. The mixing ratio of the good solvent of the polymer resin and water is preferably O to 40%, and more preferably 0 to 30%. When the mixing ratio exceeds 40%, the coagulation rate becomes slow, so the polymer solution formed into droplets etc. enters between the poor solvent and the molded body between the poor solvent and the molded body. The shape tends to be distorted by the influence of friction resistance.

The temperature of the poor solvent is not particularly limited, but is preferably −30 ° C. to 90 ° C., more preferably O ° C. to 90 ° C., and further preferably 0 ° C. to 80 ° C. If the temperature of the poor solvent exceeds 90 ° C or is less than -30 ° C, the state of the molded body in the poor solvent is difficult to stabilize.
The ions to be adsorbed by the porous molded body used in the present invention are not particularly limited to anions and cations. For example, with anions, phosphorus (phosphate ions), fluorine (fluoride ions), arsenic (arsenate ions, arsenite ions), boron (borate ions), iodine ions, chlorine ions, sulfate ions, nitrate ions , Nitrite ions, and ions of various organic acids such as acetic acid. Examples of the cation include sodium, potassium, calcium, cadmium, lead, chromium, cobalt, strontium, and cesium.

  Next, the ion adsorption process which comprises the water treatment apparatus of this invention is demonstrated. In the ion adsorption treatment of the present invention, the porous molded body described above is used as an adsorbent, and the porous molded body is brought into contact with water to be treated to adsorb ions contained in the water to the porous molded body. It is a process to remove. Normally, a porous molded body is used by filling in a container, and as for the shape of the container and the shape of the packed layer of the porous molded body, as long as the porous molded body and the water to be treated can be contacted, There is no limit, for example, it can be filled into a cylindrical, columnar, polygonal column, box-shaped container and used as a column, an adsorption tower, an adsorption tank, etc. The high contact efficiency, which is a characteristic of the porous molded body, can be sufficiently extracted when the liquid is passed through and brought into contact.

These containers are preferably provided with a solid-liquid separation mechanism that prevents the porous molded body from flowing out of the container, for example, installation of a pan and mesh.
The material of the container is not particularly limited, and examples include stainless steel, FRP (reinforced plastic with glass fiber), glass, and various plastics. In consideration of acid resistance, the inner surface may be made of rubber or fluororesin lining.

The contact method between the porous molded body and the water to be treated is not particularly limited as long as the porous molded body can be brought into contact with the water to be treated. In the case where the packed bed of the porous molded body is a fixed bed, a method of passing water in an upward flow or a downward flow through the packed bed of a cylindrical, polygonal, box-shaped porous molded body,
An external pressure system that allows water to flow from the outside in the circumferential direction to the inner cylinder through the packed layer of the cylindrical porous molded body, an internal pressure system that allows water to flow in the opposite direction, a system that allows water to flow horizontally through the box-shaped packed bed, etc. It can be illustrated. The packed bed of the porous molded body may be a fluidized bed system.

  The packed layer of the porous molded body may be filled with only one kind of the above-mentioned porous molded body, or may be filled with a mixture of a plurality of types of the above-described porous molded bodies. Furthermore, the porous molded body described above and other ion exchangers such as anion exchange resins and cation exchange resins and adsorbents may be mixed and filled.

  The ion adsorption treatment means of the present invention is not particularly limited, but can adopt a merry-go-round system. The merry-go-round method is to place a plurality of ion adsorption treatment means in series and perform water flow, and when the adsorption capacity of the ion adsorption treatment means in the previous stage decreases, the water flow of the ion adsorption treatment means is stopped and positioned in the subsequent stage. This means that the treated water with a stable water quality is obtained by sequentially passing water through the ion adsorption treatment means at a time difference from the previous stage, such as passing the ion adsorption treatment means that has been performed as the first stage. .

  In the ion adsorption treatment of the present invention, a desorption operation and an activation operation described later are generally performed at the same site where the adsorption operation is performed. However, if there is not enough space at the site or the frequency of desorption is low, only the column can be removed from the apparatus and replaced with a new column separately. The removed column can be separately processed and reused in a factory equipped with a desorption and activation facility.

In the adsorption step of the present invention, it is preferable to adsorb the ions to be adsorbed after adjusting the pH of the liquid to a suitable pH by a combination of ions to be adsorbed and the inorganic ion adsorbent.
For example, the pH adjustment range when using an inorganic ion adsorbent having a structure in which phosphorus in a liquid is to be adsorbed and hydrated zirconium oxide or iron tetroxide is covered with hydrated zirconium oxide is pH 1.5 to 10. The range is preferred, and more preferably pH 2-7.

In addition, the pH adjustment range when using an inorganic ion adsorbent with a structure in which boron in the liquid is the target of adsorption and hydrated cerium oxide or triiron tetroxide is covered with hydrated cerium oxide is in the range of pH 3 to 10. More preferably, the pH is 5-8.
In addition, the pH adjustment range when using an inorganic ion adsorbent with a structure in which fluorine in the liquid is to be adsorbed and hydrated cerium oxide or iron tetroxide is covered with hydrated zirconium oxide is in the range of pH 1-7. More preferably, it is pH 2-5.
In addition, the pH adjustment range when using an inorganic ion adsorbent with a structure in which arsenic in the liquid is the target of adsorption and hydrated cerium oxide or iron tetroxide is covered with hydrated cerium oxide is within the range of pH 3-12. Preferably, it is pH 5-9.

The porous molded body of the present invention can adsorb the anions again by contacting the alkaline aqueous solution to desorb the adsorbed anions and then treating the adsorbent with an acidic aqueous solution (re-applying). Use). By reusing the porous molded body, not only the cost can be reduced, but also the waste can be reduced. In particular, since the porous molded body of the present invention is excellent in durability, it is suitable for repeated use.
An anion can be eliminated when the pH of the alkaline solution is at least pH 10, but is preferably at least pH 12, more preferably at least pH 13. The alkali concentration is preferably in the range of O.1 wt% to 30 wt%, more preferably in the range of 0.5 to 20 wt%. If it is thinner than O.1 wt%, the desorption efficiency is low, and if it is thicker than 30 wt%, the cost of alkali chemicals tends to increase.

The flow rate of the alkaline aqueous solution is not particularly limited, but is usually preferably in the range of SV0.5 to 15 (hr ⁻¹ ). When it is lower than SVO.5, the desorption time tends to be long and tends to be inefficient, and when it is larger than SV15, the contact time between the porous molded body and the alkaline aqueous solution is shortened, and the desorption efficiency tends to decrease. The kind of the alkaline aqueous solution is not particularly limited, but usually an inorganic alkali such as sodium hydroxide aqueous solution, potassium hydroxide aqueous solution, ammonium hydroxide, and organic amines are used. Of these, sodium hydroxide and potassium hydroxide are particularly preferred because of their high desorption efficiency.

  In the present invention, the desorbing alkali recycling step and the desorbing ion recovery step are performed by bringing an alkaline aqueous solution into contact with the porous molded body of the present invention that has adsorbed ions, eluting the ions in the alkaline solution, By adding a crystallization agent that generates ions and a precipitate and removing the precipitate, the alkali can be reused, and the ions can be recovered as a precipitate.

Examples of the crystallization agent include metal hydroxides. In the metal hydroxide, a metal salt is combined with anions such as phosphoric acid, boronic acid, fluorine, arsenic, and arsenous acid to form a precipitate. Further, since the hydroxide becomes an alkali source of the desorption liquid, a closed system can be obtained by collecting and recycling the regenerated liquid. Specific examples include sodium hydroxide, aluminum hydroxide, magnesium hydroxide, and calcium hydroxide.
From the viewpoint of obtaining a hardly soluble precipitate, that is, a precipitate having low solubility, a polyvalent metal hydroxide is preferable, and specifically, aluminum hydroxide, magnesium hydroxide, and calcium hydroxide are particularly preferable. In particular, calcium hydroxide is preferable in terms of cost.

For example, when fluorine is present as sodium fluoride in the eluent, high-concentration alkali can be recovered according to the following reaction formula.
2NaF + Ca (OH) ₂ → 2NaOH + CaF ₂ ↓
Similarly, when it exists as sodium phosphate, the alkali can be recovered according to the following reaction formula. Furthermore, the crystallized calcium phosphate can be recycled into fertilizers and the like.
6Na ₃ PO ₄ + 10Ca (OH) ₂ → 18NaOH + Ca10 (OH) ₂ (PO ₄ ) ₆ ↓
The addition amount of the metal hydroxide is not particularly limited, but is 1 to 4 times equivalent to the target ion. When the addition amount is equal to or less than the equimolar amount, the precipitation removal efficiency is low, and when it exceeds 4 times the equivalent, the removal efficiency hardly changes and tends to be economically disadvantageous.

  When removing the precipitate, the pH is preferably 6 or more. Further, considering that the aqueous alkaline solution is recovered and reused, it is preferably maintained at pH 12 or more, preferably pH 13 or more. If the pH during the precipitation process is lower than 6, the solubility of the precipitate increases and the precipitation efficiency decreases. When removing the precipitate, an inorganic flocculant such as aluminum sulfate or polyaluminum chloride or a polymer flocculant can be used in combination with the metal hydroxide.

Further, the preferred desorbed ion recovery step in the present invention is to cool the desorbed liquid from which ions have been desorbed and to crystallize and remove the precipitate, thereby making it possible to reuse the alkali, Can be recovered.
This recovery process of desorbed ions by cooling can be suitably applied particularly when a porous molded body that has adsorbed phosphate ions is desorbed using sodium hydroxide.

The cooling means and method are not particularly limited, but can be cooled using a normal chiller, heat exchanger or the like.
The cooling temperature is not particularly limited as long as it is a temperature at which desorbed ions can be crystallized, but is preferably in the range of 5 to 25 ° C, more preferably in the range of 5 to 10 ° C. If the temperature is less than 5 ° C, a large amount of cooling energy is required, which tends to be economically disadvantageous. If the temperature is higher than 10 ° C, the effect of crystallizing the precipitate tends to be low.

In order to effectively crystallize sodium phosphate by cooling, sodium hydroxide can be newly added to increase the concentration of sodium hydroxide in the desorption liquid.
In the present invention, the solid-liquid separation method of the precipitate in the eluent is preferably a membrane separation method.
The membrane separation method is suitable for a closed system such as the present invention because it requires a small installation area and can obtain a clear filtered water.
The membrane separation method is not particularly limited, and examples thereof include an ultrafiltration membrane (UF), a microfiltration membrane (MF), and a dialysis membrane. The form of the membrane is not limited to a flat membrane, a hollow fiber, a pleat, a tube shape or the like. As a preferable membrane separation method, an ultrafiltration membrane (UF), a microfiltration membrane (MF) and the like are preferable in terms of filtration speed and filtration accuracy.

The porous molded body in the column after the desorption step is alkaline, and as it is, the ability to adsorb ions in the raw water again is low. Therefore, an operation of returning the pH in the column to a predetermined value using an acidic aqueous solution, that is, an activation treatment is performed.
The acidic aqueous solution is not particularly limited, but an aqueous solution such as sulfuric acid and hydrochloric acid is used. The concentration may be about O.001 to 10 wt%. If it is thinner than O.001 wt%, a large amount of water volume is required by the end of activation, and if it is thicker than 10 wt%, there is a possibility that a problem may occur in terms of danger in handling an acidic aqueous solution.
The liquid passing speed is not particularly limited, but is usually preferably in the range of SV 0.5 to 30 (hr ⁻¹ ). If it is lower than SV0.5, the activation time tends to be long and inefficient, and if it is larger than SV30, the contact time between the porous molded body and the acidic aqueous solution becomes short, and the activation efficiency tends to decrease. is there.

A more preferable method in the activation method is to circulate the active solution between the column and the pH adjusting tank.
By adopting this configuration, the pH of the porous molded body in the column shifted to the alkali side by the desorption operation can be slowly returned to a predetermined pH in consideration of the acid resistance of the inorganic ion adsorbent.
For example, it is known that iron oxide is remarkably dissolved by acid at pH 3 or lower. When such iron oxide is supported on a porous molded body, the conventional activation method has a problem of dissolution of iron, and therefore, there is only a method of treating with a thin acid having a pH of 3 or more. However, this method requires a large volume of water and is not economically acceptable.

In contrast to such conventional techniques, the activation method of the present invention is provided with a column and a pH adjusting tank and circulates the activation liquid. Therefore, the activation method can be activated while avoiding the pH range in which it is dissolved by an acid. The volume of water used for conversion can be reduced, and the apparatus can be made compact.
The liquid passing speed at this time is usually selected in the range of SV1 to 200 (hr ⁻¹ ). More preferably, it is in the range of SV1O-100. If it is lower than SV1, the activation time tends to be long and tends to be inefficient, and if it is larger than SV200, a large pump movement is required and tends to be inefficient.
This series of desorption and activation operations can be performed while the column is filled with the adsorbent. That is, regeneration can be easily performed by passing an alkaline aqueous solution and an acidic aqueous solution sequentially through the column after the adsorption operation is completed in the column packed with the adsorbent. In this case, the liquid flow direction may be either an upward flow or a downward flow.

Since the porous molded body used in the present invention is excellent in chemical resistance and strength, even if this regeneration treatment is repeated several tens to several hundred times or more, the ion adsorption performance hardly decreases.
In the water treatment apparatus of the present invention, the order in which the desalting treatment and the ion adsorption treatment are combined is not particularly limited, but the ion adsorption treatment is preferably performed after the desalting treatment.

  Furthermore, it is preferable that the water treatment apparatus and the water treatment method of the present invention include a filtration treatment for removing suspended substances and organic substances contained in the water to be treated as a pretreatment system. By removing suspended substances in water in advance, blockage of the surface of the porous molded body can be prevented, and the adsorption performance of the porous molded body can be sufficiently exhibited. Preferable filtration treatment includes treatment by a coagulation sedimentation device, a sedimentation separation device, a sand filtration device, and a membrane separation device. In particular, treatment with a membrane separation apparatus that has a small installation area and that can provide clear filtered water is preferable. Preferred membrane separation techniques include ultrafiltration membrane (UF), microfiltration membrane (MF) and the like. The form of the membrane is not limited to flat membranes, hollow fibers, pleats, spirals, tubes and the like.

In addition, the water treatment apparatus and the water treatment method of the present invention include dissolved organic matter contained in the water to be treated, activated carbon adsorption treatment for removing free chlorine, deaeration treatment for removing dissolved gas in water, If necessary, ultraviolet oxidation treatment for decomposing organic substances remaining in the water, pH adjustment treatment for adjusting the pH of water to be treated, and the like may be combined.
Examples of raw water to be treated by the water treatment apparatus and water treatment method of the present invention include tap water, drinking water, industrial water, factory process water, river water, lake water, seawater, brine, irrigation water, groundwater, and Sewage, factory wastewater, activated sludge from sewage treatment plants and wastewater treatment facilities, desulfurization flue gas from thermal power plants, etc., but desalination treatment of seawater and brackish water, purification of river water, lake water, and groundwater It can be particularly preferably used for water purification treatment, tap water, ultrapure water treatment of groundwater, sewage, wastewater treatment of factory wastewater and the like.

  EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited at all by these.

In the examples, various physical properties of the molded bodies were measured by the following methods.
-Observation of molded body with scanning electron microscope The molded body was observed with a scanning electron microscope (SEM) using an S-800 scanning electron microscope manufactured by Meidari Seisakusho.
-Cleaving of the molded body The molded body was vacuum-dried at room temperature, and the dried molded body was added to isopropyl alcohol (IPA) to impregnate the molded body with IPA. Next, the molded body was enclosed with IPA in a gelatin capsule having a diameter of 5 mm and frozen in liquid nitrogen. The frozen molded body was cleaved together with the engraved sword. The cut molded body was selected as a microscope sample.

-Surface aperture ratio An image of the surface of the molded body taken using a scanning electron microscope was determined using image analysis software (Win Roof (trade name) manufactured by Mitani Corporation). In more detail, the obtained SEM image is recognized as a grayscale image, and the threshold is manually adjusted by dividing the dark portion into an opening and the light portion as a fibril, and dividing it into an opening portion and a fibril portion. Then, the area ratio was obtained. -Aperture diameter of the surface It was obtained by actual measurement from the image of the surface of the molded body taken using a scanning electron microscope. When the hole was circular, the diameter was used. When the hole was not circular, the equivalent circle diameter of a circle having the same area was used.

-Particle size The particle size of the compact and the inorganic ion adsorbent was measured with a laser diffraction / scattering particle size distribution analyzer (LA-910 (trade name) manufactured by HORIBA). However, when the particle size was 1 or more than OOO μm, the longest diameter and the shortest diameter of the molded body were measured using an SEM image, and the average value was taken as the particle size.
-Porosity A molded product that had been sufficiently wetted with water was spread on a dry filter paper, and after removing excess water, the weight was measured to obtain the weight (W1) of the molded product when it contained water. Next, the molded body was vacuum-dried at room temperature for 24 hours to obtain a dried molded body. The weight of the dried molded body was measured and taken as the weight (W0) when the molded body was dried.

Next, a specific gravity bottle (Geryusac type, capacity 10 m1) was prepared, and the weight when the specific gravity bottle was filled with pure water (25 ° C.) was measured to obtain the weight at the time of full water (Ww). Next, a molded body wet in pure water was placed in this specific gravity bottle, and the weight was measured by filling the marked water with pure water to obtain (Wwm). Next, the molded body was taken out from the specific gravity bottle and subjected to vacuum drying at room temperature for 24 hours to obtain a dried molded body. The weight of the dried molded body was measured and determined as (M).
The specific gravity (ρ) and porosity (Pr) of the molded body were determined according to the following calculation formula.
ρ = M / (Ww + M-Wwm)
Pr = (W1-W0) / (W1-W0 + W0 / ρ) × 100
In the formula, Pr is the porosity (%), W1 is the weight (g) of the molded body when it contains water, WO is the weight (g) after drying the molded body, and ρ is the specific gravity (g / cm ³ ), M is the weight of the molded body after drying (g), Ww is the weight when the specific gravity bottle is full (g), and Wwm is the weight of the specific gravity bottle when water and the pure water are added ( g).

-Loading amount The molded body was dried at room temperature by vacuum drying for 24 hours to obtain a dried molded body. The weight of the dried molded body was measured and used as the weight Wd (g) when the molded body was dried. Next, the dried molded body was calcined at 800 ° C. for 2 hours using an electric furnace, and the weight of ash was measured to obtain the weight of ash Wa (g). The supported amount was determined from the following formula.
Load (%) = Wa / Wd x 100
In the formula, Wa is the weight (g) of the ash content of the molded body, and Wd is the weight (g) when the molded body is dried.

・ Specific surface area (m ² / cm ³ )
After the molded body was vacuum-dried at room temperature, the specific surface area S _BET (m ² / g) of the porous molded body was determined by the BET method using Beckman Coulter Co., Ltd. Coulter SA3100 (trade name).
Next, the apparent volume V (cm ³ ) of the wet compact was measured using a graduated cylinder or the like. Thereafter, vacuum drying is performed at room temperature to determine the weight W (g).
The specific surface area of the molded product of the present invention was determined from the following equation.
Specific surface area (m ² / cm ³ ) = S _BET × Bulk specific gravity (g / cm ³ )
Bulk specific gravity (g / cm ³ ) = W / V
In the formula, SS _BET is the specific surface area (m ² / g) of the molded body, W is the dry weight (g) of the molded body, and V is the apparent volume (cm ³ ).

・ Boron concentration measurement
It was measured by an ICP emission method (Thermo Electron Co., Ltd. (USA), IRIS-INTREPID-II (trade name)).

(Production Example) Production of Porous Molded Body 0.2 mol of cerium sulfate and 0.5 mol of ammonium sulfate were dissolved in 2 liters of distilled water with stirring. Next, aqueous ammonia was added to adjust the pH of the solution to 9 to obtain a precipitate. After aging overnight, it was filtered, washed with deionized water until the filtrate was neutral, and then dried at 60 ° C. This was pulverized with a ball mill for 7 hours to obtain hydrous cerium hydroxide powder having an average particle size of 2.0 μm.
Next, ethylene vinyl alcohol copolymer (EVOH, Nippon Synthetic Chemical Industry Co., Ltd., Soarnol E3803 (trade name)) 10 g, polyvinyl pyrrolidone (PVP, BASF Japan Ltd., Luvitec K30 Powder (trade name)) 10 g, dimethyl 80 g of sulfoxide (DMSO, Kanto Chemical Co., Inc.) was dissolved by heating at 60 ° C. in a Separa flask to obtain a uniform polymer solution.
To 100 g of this polymer solution, 125 g of the above-mentioned hydrated cerium oxide powder was added and mixed well to obtain a slurry.

The obtained composite polymer slurry was heated to 40 ° C., and supplied to the inside of a cylindrical rotating container having a nozzle with a diameter of 5 mm on the side. The container was rotated, and the liquid was discharged from the nozzle by centrifugal force (17.5 G). Drops were formed and discharged into a coagulation bath made of water at 60 ° C. to coagulate the composite polymer slurry. Furthermore, washing and classification were performed to obtain a spherical porous molded body having an average particle size of 531 μm. This spherical porous molded body had a porosity of 79%, a surface opening diameter of 0.1 to 20 μm, a loading amount of 89%, a surface opening ratio of 30%, and a specific surface area of 84 m ² / cm ³ .

  Furthermore, when the surface and fractured surface of the obtained porous molded body were observed using a scanning electron microscope (SEM), the presence of the skin layer was not observed. In addition, a maximum pore diameter layer (void layer) was observed near the surface, and voids inside the fibril and pores on the fibril surface were also confirmed. Furthermore, it was observed that the inorganic ion adsorbent powder was supported on the outer surface of the fibril and the void surface inside the fibril.

(Example 1) Boric acid adsorption test and seawater desalination treatment Boric acid (H ₃ BO ₄ ) was dissolved in distilled water to make an aqueous boric acid solution (22 mg-B / liter as boron), and sulfuric acid and sodium hydroxide were added. The pH was adjusted to 3, 5, and 7 using. To 1 liter of this aqueous solution, 2 ml of the porous molded body produced in the production example was added, and the mixture was stirred with a mechanical machine. Two hours after the start of stirring, the aqueous solution was sampled and the boric acid concentration was measured to determine the adsorption amount. Boron adsorption amount is 0.4g-B / liter at pH 3, 0.4g-B / liter at pH 5, 0.7g-B / liter at pH 7, and boron ion has a large adsorption amount in neutral region. I understood.

Next, the water treatment apparatus of the present invention in which the reverse osmosis membrane treatment as shown in the flow outline in FIG. 1 and the ion exchange treatment using the porous molded body produced in the production example as an adsorbent is produced. The seawater was desalinated with this device.
Seawater (boron concentration: 4.4 mg / g) was supplied to this apparatus as raw water for treatment.
For the pretreatment filtration, a UF membrane (microfiltration membrane: molecular weight cut off 150,000) was used, and the water flow rate was 5 m ³ / day.

  The reverse osmosis membrane treatment was performed with an apparatus using a reverse osmosis membrane (hollow type HR5355 (trade name) manufactured by Toyobo). The boron concentration in the water supplied to this apparatus was 4.4 mg / g, and the boron concentration in the treated water was 1.9 mg / g. That is, the boron concentration was not less than the recommended value of WHO only by this treatment.

The water subjected to the reverse osmosis membrane treatment was subjected to an ion exchange treatment using the porous molded body produced in the production example as an adsorbent.
This process was performed under the following conditions.
Adsorbent used: Porous molded product produced in the production example Tower column: 22Φ × 1000 Lmm
Adsorbent layer thickness: 600mm
Adsorbent amount: 228ml
Water flow rate: SV20 4.56 L / hour The boron concentration in water (fresh water) after the ion exchange treatment was less than 0.01 mg / L.

  The water treatment apparatus and water treatment method of the present invention include seawater and brackish water desalination treatment, river water, lake water, groundwater purification treatment, water purification treatment, tap water, groundwater ultrapure water treatment, sewage, factory It can be preferably used in fields such as wastewater treatment of wastewater.

The flow schematic diagram of the water treatment equipment of an example.

Explanation of symbols

1 Raw water (seawater)
2 Pretreatment system (filtration equipment)
DESCRIPTION OF SYMBOLS 3 Reverse osmosis membrane apparatus 4 Ion adsorption apparatus 401 Porous molded object manufactured by manufacture example 5 Fresh water

Claims (8)

  A water treatment apparatus comprising a desalination treatment means and an ion adsorption treatment means using a porous molded article as an adsorbent, wherein the porous molded article comprises an organic polymer resin and an inorganic ion adsorbent. A porous molded body having a communication hole opened on the surface, having a void inside the fibril forming the communication hole, and at least a part of the void is open on the surface of the fibril, the fibril A water treatment apparatus, wherein an inorganic ion adsorbent is supported on the outer surface and the inner void surface.   The water treatment apparatus according to claim 1, wherein the communication hole has a maximum pore diameter layer in the vicinity of the surface of the molded body.   The water treatment apparatus according to claim 1 or 2, wherein the porous molded body has an average particle size of 100 to 2500 µm and is substantially spherical.   The porous molded body contains at least one selected from the group consisting of ethylene vinyl alcohol copolymer (EVOH), polyacrylonitrile (PAN), polysulfone (PS), and polyvinylidene fluoride (PVDF) as an organic polymer resin. The water treatment apparatus according to claim 1, wherein the water treatment apparatus is a porous molded body. The water treatment apparatus according to any one of claims 1 to 4, wherein the inorganic ion adsorbent contains at least one metal oxide represented by the following formula (I).
_{MN x O n · mH 2 O} (I)
(Wherein x is 0 to 3, n is 1 to 4, m is 0 to 6, and M and N are Ti, Zr, Sn, Sc, Y, La, Ce, Pr, Nd, Sm, Eu. Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Al, Si, Cr, Co, Ga, Fe, Mn, Ni, V, Ge, Nb and Ta are metal elements selected from the group Are different from each other.) 6. The water according to claim 5, wherein the metal oxide represented by the formula (I) is one or a mixture selected from any of the following groups (a) to (c): Processing equipment.
(A) hydrated titanium oxide, hydrated zirconium oxide, hydrated tin oxide, hydrated cerium oxide, hydrated lanthanum oxide, and hydrated yttrium oxide (b) consisting of titanium, zirconium, tin, cerium, lanthanum, and yttrium A composite metal oxide of a metal element selected from the group and a metal element selected from the group consisting of aluminum, silicon, and iron (c) activated alumina   The water treatment apparatus according to any one of claims 1 to 6, wherein the ions to be adsorbed by the ion adsorption treatment means are phosphorus, boron, fluorine and / or arsenic.   A water treatment method comprising, in this order, a desalination treatment step and an ion adsorption treatment step using a porous molded article as an adsorbent, wherein the porous molded article comprises an organic polymer resin and an inorganic ion adsorbent. A porous molded body having a communication hole that opens to the outer surface, and has a void inside the fibril forming the communication hole, and at least a part of the void is open on the surface of the fibril. A water treatment method characterized in that an inorganic ion adsorbent is supported on the outer surface of the fibril and the surface of the internal void.

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