JP2008238132A - Adsorption apparatus and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adsorption apparatus and a method by which ions in water are removed and recovered and treatment can be carried out with small occupied volume even when a large amount water containing ions of small ionic character such as a phosphate ion is treated. <P>SOLUTION: In a moving bed type adsorption apparatus charged with an adsorbent, the adsorbent comprises an organic polymer resin and an inorganic ion adsorbent and has an communicative hole opened to an outer surface. The adsorbent has a void inside a fibril forming the communicative hole and at least a part of the void opens at a fibril surface and the inorganic ion adsorbent is carried on an outer surface of the fibril and on an inside void surface. Further the treating method using the adsorption apparatus is also provided. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an adsorption apparatus and a treatment method for removing and collecting ions in water with an adsorbent.

As an apparatus for removing and collecting ions in water, a moving bed type adsorption apparatus filled with an adsorbent is known. Conventional adsorption devices use an ion exchange resin or a chelate resin as an adsorbent, and are used for deionization from river water or groundwater. It has the feature that the device is compact and simple. When removing highly ionic ions such as sodium ions and calcium ions, such as deionization, sufficient performance can be achieved just by using a normal ion exchange resin, etc. When removing ions with such low ionicity, the adsorption rate was slow, so the advantage of the moving bed type could not be demonstrated.
AAZagorodni, Ion Exchange Materials Properties and Applications, Elsevier Publishing (2007)

  The present invention relates to an adsorption apparatus and a treatment method for removing and recovering ions in water, and an adsorption capable of treating with a small occupied volume even when treating a large amount of water containing small ionic ions such as phosphate ions. An object is to provide an apparatus and method.

  In order to solve the above-mentioned problems, the present inventor has found a moving bed type adsorption apparatus and method newly filled with an adsorbent, and has made the present invention. That is, the present invention relates to (1) a moving bed type adsorber filled with an adsorbent, wherein the adsorbent comprises an organic polymer resin and an inorganic ion adsorbent, and has an open hole on the outer surface. The fibrils forming communication holes have voids inside, and at least a part of the voids are opened on the surface of the fibrils, and inorganic ions are present on the outer surface of the fibrils and on the surface of the voids inside. In an adsorption apparatus that is an adsorbent carrying an adsorbent, and (2) a treatment method using a moving bed adsorber filled with an adsorbent, the adsorbent is an organic polymer resin and an inorganic ion adsorbent. An adsorbent having a communication hole that opens to the outer surface, comprising a void inside the fibril that forms the communication hole, and at least a part of the void is open on the surface of the fibril The fib Inorganic ion adsorbent to the outer surface and inside of the air gap surface of Le is a processing method which is adsorbent is carried.

  The adsorption device and the treatment method of the present invention are an adsorption device and a treatment method for removing and recovering ions in water, and have an effect that a large amount of water can be treated with a small occupied volume.

  The present invention will be specifically described below.

  The present invention relates to a moving bed type adsorption apparatus filled with an adsorbent, wherein the adsorbent comprises an organic polymer resin and an inorganic ion adsorbent, and has an open hole on the outer surface, There is a void inside the fibril forming the communication hole, and at least a part of the void is opened on the surface of the fibril, and the inorganic ion adsorbent is supported on the outer surface of the fibril and the inner void surface. The present invention relates to an adsorbing apparatus and a processing method which are adsorbents.

  The adsorbent of the present invention will be described in detail below.

  First, the structure of the adsorbent of the present invention will be described.

  The adsorbent of the present invention has communication holes and a porous structure. Furthermore, there is no skin layer on the outer surface, and the surface has excellent opening properties. 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 opening ratio of the adsorbent of the present invention refers to the ratio of the sum of the opening 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 adsorbent 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 the substance to be adsorbed, such as phosphorus, into the adsorbent becomes slow. On the other hand, if it exceeds 90%, the adsorbent has insufficient strength and it is difficult to realize an adsorbent with excellent chemical strength. It is. The outer surface opening diameter of the adsorbent of 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 the adsorption target substance such as phosphorus into the adsorbent tends to be slow, whereas if it exceeds 100 μm, the adsorbent strength tends to be insufficient.

  The adsorbent of the present invention has voids in the fibrils forming the communication 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 an adsorption target substance called phosphorus, and can effectively function as an adsorbent. Since the adsorbent of the present invention is porous even in such a portion where the adsorption substrate is supported, the fine adsorption site of the adsorption substrate, which was a drawback of the conventional method of kneading the adsorption substrate and the binder, However, the adsorption substrate can be used effectively. Here, the fibril means a fibrous structure made of an organic polymer resin and forming a three-dimensional continuous network structure on the outer surface and inside of the adsorbent. The voids inside the fibril and the openings on the fibril surface are determined by observing the cut section of the adsorbent 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.

  In the adsorbent of the present invention, the communicating holes preferably have a maximum pore diameter layer in the vicinity of the adsorbent surface. Here, the maximum pore diameter layer refers to the largest portion in the pore diameter distribution of the communication holes extending from the surface of the adsorbent 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 cleaving diameter of the adsorbent from the outer surface toward the center. By having the maximum pore diameter layer in the vicinity of the adsorbent surface, it has the effect of accelerating the diffusion of the substance to be adsorbed into the interior. Therefore, an adsorption target substance such as phosphorus can be quickly taken into the adsorbent and removed from the treated water. The position of the maximum pore diameter and the maximum pore diameter layer is obtained by observing the surface and the fractured surface of the adsorbent 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 adsorbent 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. In particular, when the adsorbent is used as an adsorbent in the field of water treatment, the particle shape is reduced from the point of view of pressure loss, effectiveness of contact area, and ease of handling when packed in a column or the like. Spherical particles (not only true spheres but also oval spheres) are particularly preferable.

  The average particle diameter of the spherical adsorbent of the present invention is the mode diameter (most frequent particle diameter) of the sphere equivalent diameter obtained from the angle distribution of the 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 100 μm, the pressure loss tends to increase when the column or tank is filled, and if the average particle size is larger than 2500 μm, the surface area when packed in the column or tank is reduced. Processing efficiency tends to decrease.

  The porosity Pr (%) of the adsorbent of the present invention is the weight W1 (g) when the adsorbent is wet, the weight W0 (g) after drying, and the specific gravity of the adsorbent as ρ, A value represented by: Pr = (W1-WO) / (W1-WO + W0 / ρ) × 100. The weight when water is contained may be determined by spreading an adsorbent sufficiently wet with water on dry filter paper and taking excess water before measuring the weight when containing water. Drying may be performed under vacuum at room temperature in order to eliminate moisture. The specific gravity of the adsorbent 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 adsorption target substance such as phosphorus and the inorganic ion adsorbent as the adsorption substrate tends to be insufficient. If it exceeds 90%, the adsorbent strength tends to be insufficient.

  The supported amount of the inorganic ion adsorbent of the adsorbent of the present invention means the value represented by the following formula when the adsorbent weight Wd (g) and the ash weight Wa (g) are expressed: %) = Wa / Wd × 100, where the ash content is the residue when the adsorbent of the present invention is calcined 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 adsorption target substance such as phosphorus and the inorganic ion adsorbent as the adsorption substrate tends to be insufficient, and if it exceeds 95%, the strength of the adsorbent tends to be insufficient. According to the method of the present invention, unlike the conventional adhering method, the adsorbing substrate and the organic polymer resin are kneaded and molded, so that an adsorbent having a high supported amount and strong strength can be obtained.

The specific surface area of the adsorbent of the present invention is defined by the following formula: specific surface area (m ² / cm ³ ) = S _BET × bulk specific gravity (g / cm ³ ), where S _BET is a unit of adsorbent Specific surface area per weight (m ² / g). The specific surface area is measured using the BET method after the adsorbent is vacuum dried at room temperature. The bulk specific gravity is measured by measuring the apparent volume using a wet adsorbent and a graduated cylinder or the like for those having a short shape such as a particle, column, or hollow 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 amount of adsorbing substrate supported and the adsorption performance tend to be insufficient. If it exceeds 500 m ² / cm ³ , the adsorbent strength 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 adsorbent of 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.

  Next, a method for producing the adsorbent of the present invention will be described.

  The method for producing an adsorbent of the present invention is characterized in that an organic polymer resin, a good solvent thereof, an inorganic ion adsorbent, and a water-soluble polymer are mixed and then molded and coagulated in a poor solvent.

The organic polymer resin used in the present invention 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. In addition, the good solvent used in the present invention may be any 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 adsorbent. If it exceeds 40% by weight, it is difficult to obtain an adsorbent with a high porosity. The water-soluble polymer used in the present invention 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, it is particularly preferable to use polyvinyl pyrrolidone as the water-soluble polymer because it has a high effect of developing a structure having voids inside the fibrils forming the communicating holes as in the adsorbent of the present invention. 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 adsorbent of the present invention is expressed by the following equation when the weight when the adsorbent is dried is Wd (g) and the weight of the water-soluble polymer extracted from the adsorbent is Ws (g). The value expressed is: 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 adsorbent, 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 adsorbent is measured as follows. First, after the dried adsorbent 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 adsorbent 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 ion adsorbent A solution obtained by filtering the solution is prepared, and then the liquid is 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 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 and insoluble hydrated 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 composite metal hydroxides, metal oxides, metal hydrated oxides, polyvalent metal acid salts, insoluble heteropolyacid salts, insoluble hexacyanoferrates, and the like.

  Examples of the composite metal hydroxide include hydrotalcite compounds represented by the following formula (III).

M ²⁺ _(1-X) M ³⁺ _x (OH ⁻ ) _{(2 + xy)} (A ⁿ⁻ ) y / n
(III)
[In the formula, M ²⁺ is Mg ²⁺ , Ni ²⁺ , Zn ²⁺ , Fe ²⁺ , Ca
^And at least one divalent metal ion selected from the group consisting of ²⁺ and Cu ²⁺ , and M 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, and 0.1 ≦ x ≦
0.5, 0.1 ≦ y ≦ 0.5, and n is 1 or 2. ]
Examples of the metal oxide include activated alumina, iron oxide such as FeO, Fe ₂ O ₃ , and Fe ₃ O ₄ , silica gel, and the like.

  The metal hydrous oxide can be represented by the formula (I) or the formula (II). A mixture of any combination of the formulas (I) and (II) may be used.

MO _n · mH ₂ O (I)
_{M · Fe 2 O 4 · mH} 2 O + xFe 3 O 4 · nH 2 O (II)
In the formula, n is 1 to 4, m is 0.5 to 6, and x is 0 to 3.
The formula (I) is a general formula of hydrated oxide, and the formula (II) is a mixture of hydrous ferrite and hydrated oxide of iron. In the formula, M is Ti, Zr, Sn, Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Al, Cr, Co, Ga. Fe, Mn, Ni, V, Ge, Nb and at least one metal selected from the group consisting of Ta. In formula (II), + represents a mixture. In particular, Ti, Zr, Sn, and Ce are preferable in terms of adsorption capacity and resistance to dissolution in acids and alkalis.

  Furthermore, in consideration of economy, a mixture of the hydrated ferrite of formula (II) and iron hydrated oxide is preferable. More preferably, the metal M of the hydrous ferrite of the formula (II) is Zr.

  Specific examples of the hydrated oxide represented by the formula (I) include the following.

As a hydrated oxide of titanium, the general formula TiO ₂ · nH ₂ O
(Wherein n is a number from 0.5 to 2.0).
As a hydrated oxide of zirconium, the general formula ZrO ₂ · nH ₂ O
(Wherein n is a number from 0.5 to 2.0).
As the hydrate of tin, the general formula SnO ₂ · nH ₂ O
(Wherein n is a number from 0.5 to 2.0).
As hydrated oxide of cerium, the general formula CeO ₂ · nH ₂ O
(Wherein n is a number from 0.5 to 2.0).
Specific examples of the mixture of the hydrous ferrite and the hydrated oxide of iron represented by the formula (II) include the following.

As a mixture of titanium hydrous ferrite and hydrated oxide of iron, the general formula Ti · Fe ₂ O ₄ · mH ₂ O + xFe ₃ O ₄ · nH ₂ O
(Wherein n is 1 to 4, m is 0.5 to 6, and x is a number from 0 to 3).
As a mixture of the hydrous ferrite of zirconium and the hydrated oxide of iron, the general formula Zr.Fe ₂ O ₄ .mH ₂ O + xFe ₃ O ₄ .nH ₂ O
(Wherein n is 1 to 4, m is 0.5 to 6, and x is a number from 0 to 3).
The mixture of the tin hydrous ferrite and the iron hydrated oxide has the general formula Sn.Fe ₂ O ₄ .mH ₂ O + xFe ₃ O ₄ .nH ₂ O
(Wherein n is 1 to 4, m is 0.5 to 6, and x is a number from 0 to 3).
The mixture of cerium hydrous ferrite and hydrated iron oxide is represented by the general formula Ce.Fe ₂ O ₄ .mH ₂ O + xFe ₃ O ₄ .nH ₂ O
(Wherein n is 1 to 4, m is 0.5 to 6, and x is a number from 0 to 3).

  Although the manufacturing method of the hydrated oxide represented by the formula (I) 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.

The hydrated oxide represented by the formula (II) is a mixture of hydrated ferrite and iron hydrated oxide. Although the manufacturing method of this compound is not specifically limited, For example, it manufactures with the following methods. To a solution containing metal ions prepared by dissolving the metal salt, a ferrous salt corresponding to about 0.2 to 11 times moles of metal ions contained in the solution is added, and then an alkali is added. To maintain the pH of the solution at about 6 or higher, preferably about 7-12. Thereafter, if necessary, the temperature of the solution is set to about 30 to 100 ° C., and then an oxidizing gas such as air, oxygen gas or ozone is blown in, or an oxidizing agent such as hydrogen peroxide is added, An acid salt precipitate is formed. The resulting precipitate is filtered off, washed with water 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. The moisture content after drying is preferably in the range of about 6 to 30% by weight. Here, the hydrated oxide of iron is a hydrate of an oxide of iron such as FeO, Fe ₂ O ₃ , Fe ₃ O ₄ (monohydrate, dihydrate, trihydrate, tetrahydrate, etc.) ). The ratio of the hydrous ferrite to the hydrated iron oxide is such that the hydrous ferrite content is 24 to 100% by weight, preferably 50 to 99% by weight.
Examples of the metal salt of titanium, zirconium, tin or cerium used in the above-described production method include titanium tetrachloride (TiC1 ₄ ), titanium sulfate (Ti (SO ₄ ) ₂ ), titanyl sulfate (TiO (SO ₄ )), Zirconium oxychloride (ZrOC1 ₂ ), zirconium tetrachloride (ZrC1 ₄ ), zirconium nitrate (Zr (NO ₃ ) ₄ ), zirconium sulfate (Zr (SO ₄ ) ₂ ), zirconium acetate (Zr (CH ₃ COO) ₄ ), Tin tetrachloride (SnC1 ₄ ), tin nitrate (Sn (NO ₃ ) ₄ ), tin sulfate (Sn (SO ₄ ) ₂ ), cerium tetrachloride (CeCl ₄ ), cerium nitrate (Ce (NO ₃ ) ₄ ), sulfuric acid And cerium (Ce (SO ₄ ) ₂ ). 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 ferrous salt include ferrous sulfate (FeSO ₄ ), ferrous nitrate (Fe (NO ₃ ) ₂ ), and ferrous chloride (FeC1 ₂ ). 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.

  As the inorganic ion adsorbent to be supported on the adsorbent of the present invention, titanium, zirconium, tin hydrated oxide; titanium, zirconium, tin hydrous ferrite, because of its excellent adsorption performance such as phosphorus; Preferred is at least one selected from the group consisting of hydrous cerium oxide; hydrous lanthanum oxide; activated alumina; activated alumina loaded with aluminum sulfate; and activated carbon loaded with aluminum sulfate.

  The inorganic ion adsorbent of the present invention is preferably as fine as possible, and its particle size is in the range of 0.01 to 100 μm, preferably 0.01 to 50 μm, more preferably 0.01 to 30 μm. .

  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.

  As the poor solvent of the method of the present invention, for example, water, alcohols such as methanol, ethanol, organic polymer resins such as industrial hydrocarbons, aliphatic hydrocarbons such as n-hexane and n-heptane are dissolved. Liquid is used, but water is preferred. 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 or the like is between the poor solvent and the adsorbent when entering the poor solvent and while moving in the poor solvent. 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. When the temperature of the poor solvent exceeds 90 ° C. or less than −30 ° C., the state of the adsorbent in the poor solvent is difficult to stabilize.

  The adsorbent of the present invention removes and collects ions in water by contacting with a liquid.

  The ions to be adsorbed by the adsorbent of 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.

  In particular, inorganic ion adsorbents have the characteristic of specific selectivity for certain ions, so that ions such as phosphorus are removed from the presence of miscellaneous ions such as sewage and industrial wastewater. Suitable for doing.

  Specifically, to remove phosphorus ions, an inorganic ion adsorbent is coated with titanium, zirconium, tin hydrated oxide; titanium, zirconium, tin hydrous ferrite; hydrated cerium; hydrated lanthanum; activated alumina. It is preferable to select at least one selected from the group consisting of activated alumina loaded with aluminum sulfate and activated carbon loaded with aluminum sulfate.

  The moving bed type adsorption apparatus of the present invention will be described.

  The adsorbing apparatus of the present invention can use a normal moving bed type adsorbing apparatus, and is not particularly limited.

  The adsorbing device of the present invention includes, for example, an adsorbing unit, a cleaning unit, a desorbing unit, and an activating unit connected in a loop shape. The adsorbent is filled in this loop and flows in one direction, and raw water, washing water, desorption liquid, activation liquid and the like flow opposite to the adsorbent.

  The material of the loop 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.

  When the raw water to be treated by the adsorption device contains a large amount of suspended substances, it is preferable to provide means for solid-liquid separation of suspended substances in the raw water as a pretreatment. By removing suspended substances in water in advance, the surface of the adsorbent can be prevented from being blocked, and the adsorption performance of the adsorbent of the present invention can be fully exhibited. Preferable solid-liquid separation means includes coagulation sedimentation, sedimentation separation, sand filtration, and membrane separation. In particular, a membrane separation technique that has a small installation area and that provides clear filtrate water is preferable. Preferred membrane separation techniques include reverse osmosis membrane (RO), 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 the adsorption unit, ions in the raw water are removed and collected by the adsorbent. It is preferable to adsorb the ions to be adsorbed after adjusting the pH of the raw water to a suitable pH by a combination of the ions to be adsorbed and the inorganic ion adsorbent. For example, when phosphorus in a liquid is an object to be adsorbed, the pH adjustment range when zirconium hydrous ferrite is used as the inorganic ion adsorbent is in the range of pH 1.5 to 10, more preferably pH 2 ~ 7.

  In the washing section, the suspended matter adhering to the adsorbent is backwashed with washing water. The detached suspended matter is discharged as washing wastewater.

In the desorption part, the adsorbed anion is desorbed by contacting with the alkaline aqueous solution. An anion can be eliminated when the pH of the alkaline aqueous solution is at least pH 10, but is preferably at least pH 12, more preferably at least pH 13. The alkali concentration is 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 lowered, and if it is higher than 30 wt%, the chemical cost of alkali 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 ). If it is lower than SVO.5, the desorption time tends to be long and tends to be inefficient, and if it is larger than SV15, the contact time between the adsorbent and the alkaline aqueous solution tends to be short, and the desorption efficiency tends to decrease. The type of the alkaline aqueous solution is not particularly limited, but usually, an inorganic alkali such as a sodium hydroxide aqueous solution, a potassium hydroxide aqueous solution, or 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 activation part, the anion can be adsorbed again by treating the adsorbent with an acidic aqueous solution. Since the adsorbent of the present invention is excellent in durability, it is suitable for repeated use. The adsorbent that has been desorbed is alkaline, and its 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 adsorbent and the acidic aqueous solution becomes short, and the activation efficiency tends to decrease. A more preferable method for the activation method is to circulate the active liquid between the activation unit and the pH adjusting tank. By adopting this configuration, the pH of the adsorbent in the column shifted to the alkali side by the desorption operation can be gently 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 an iron oxide is supported on an adsorbent, 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 a conventional technique, the activation method of the present invention is provided with an activation part and a pH adjustment tank, and circulates the activation liquid. The volume of water used for activation 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. Since the adsorbent of the present invention is excellent in chemical resistance and strength, even if this regeneration treatment is repeated several tens to several hundreds of times, the ion adsorption performance hardly decreases.

By adding a target ion and a crystallization agent that causes precipitation to the eluent from the desorption part and removing the precipitate, the alkali can be reused and ions can be recovered as a precipitate. Examples of the crystallization agent include metal hydroxides. In the metal hydroxide, a metal salt combines with anions such as phosphorus, boron, fluorine, and arsenic 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 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. The solid-liquid separation method of the precipitate in the eluent of the present invention 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 present invention will be described based on examples.
[Production Example 1] Production of inorganic ion adsorbent (zirconium hydrous ferrite powder) 1 liter of an O.15 molar aqueous solution of zirconium sulfate was prepared. This solution contained 13.7 g of metal ions as zirconium. In this aqueous solution, 84.Og of ferrous sulfate crystals (FeSO ₄ · 7H ₂ O) was added and dissolved while stirring. This amount corresponds to 0.3 mol of iron ion. Next, a 15% by weight sodium hydroxide solution was added dropwise to this aqueous solution while stirring until the pH of the solution reached 10. A blue-green precipitate was formed. Next, air was blown in at a flow rate of 10 liter / hour while the aqueous solution was heated to 60 ° C. If the air blowing was continued, the pH of the aqueous solution was lowered. In this case, the pH was maintained at 9.5 to 10 by dropping a 15% by weight sodium hydroxide solution. When air blowing was continued until no pH drop was observed, a black zirconium hydrous ferrite precipitate formed. The black precipitate was then filtered off with suction, washed with deionized water until the filtrate was neutral, and dried at 70 ° C. or lower. This was pulverized with a ball mill for 7 hours to obtain a zirconium hydrous ferrite powder having an average particle size of 2.5 μm.
[Production Example 2] Production method of adsorbent Ethylene vinyl alcohol copolymer (EVOH, Nippon Synthetic Chemical Industry Co., Ltd., Soarnol E3803 (trade name)) 10 g, Polyvinylpyrrolidone (PVP, BASF Japan Co., Ltd., Luvitec K30 Powder) (Product name) 10 g and dimethyl sulfoxide (DMSO, Kanto Chemical Co., Ltd.) 80 g were dissolved by heating to 60 ° C. in a Separa flask to obtain a uniform polymer solution. To 100 g of this polymer solution, 92 g of the inorganic ion adsorbent powder prepared in Production Example 1 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 surface. The container was rotated, and droplets were discharged from the nozzle by centrifugal force (15G). Was discharged into a coagulation bath made of water at 60 ° C. to coagulate the composite polymer slurry. Further, washing and classification were performed to obtain a spherical adsorbent having an average particle size of 623 μm.
[Comparative Production Example 1] Production Method of Comparative Adsorbent 60 mL of polyvinylidene chloride latex (50 wt% solid content) was added to 150 g of the zirconium hydrous ferrite powder prepared in Production Example 1 and mixed well in a plastic bag. . This was passed through a 16 mesh sieve (powder A). Next, a latex solution (B) was prepared by adding 23 g of water to 77 g of vinylidene chloride latex (solid content: 50% by weight). First, 50 g of powder A was charged while rotating the rolling granulator. While continuing to rotate, 100 g of the latex solution B and 115 g of the adsorbed powder A were added simultaneously little by little, and granulated into a spherical molded product having an average particle diameter of 650 μm. This granulated product was dried at 70 ° C. overnight to obtain a spherical adsorbent. In this adsorbent, there were hardly any communication holes opened on the outer surface, and no voids were formed inside the fibrils forming the communication holes.
[Example 1] Adsorption device and method The adsorption device used was an apparatus in which an adsorption part, a washing part, a desorption part, and an activation part were connected in a loop shape as shown in FIG. This apparatus is filled with 4 L of the adsorbent obtained in Production Example 2. Sewage secondary treated water was used as raw water, treated water from the adsorbing part was used as a cleaning liquid, a 3% sodium hydroxide aqueous solution was used as a desorption liquid, and a 0.1% sulfuric acid aqueous solution was used as an activation liquid. When raw water was passed through 40 L per hour, the raw water contained 2 mg / L of phosphate ions as phosphorus, but the phosphate ion of treated water was 0.1 mg / L as phosphorus.
[Comparative Example 1] Comparative adsorption apparatus and method The same adsorption apparatus as in Example 1 was used except that the adsorbent of Comparative Production Example 1 was used. When the raw water was passed through 40 L per hour, the phosphate ion of the treated water was about 1 mg / L as phosphorus, and phosphorus could not be removed sufficiently. When the raw water was passed through 4 L per hour, the phosphate ion of the treated water was 0.1 mg / L as phosphorus.

The adsorption apparatus and method of the present invention can be used in the field of removing and recovering ions in water. In particular, it can be suitably used in the field of removing and recovering phosphate ions from secondary treated water of organic wastewater such as sewage and industrial wastewater.

The schematic diagram of the adsorption | suction apparatus of this invention.

Explanation of symbols

  1 adsorption part, 2 cleaning part, 3 desorption part, 4 activation part

Claims (4)

  In a moving bed type adsorber filled with an adsorbent, the adsorbent is an adsorbent comprising an organic polymer resin and an inorganic ion adsorbent and having a communication hole that opens to the outer surface, and forms a communication hole. Adsorption with a void inside the fibril, and at least a part of the void is open at the surface of the fibril, and an inorganic ion adsorbent is supported on the outer surface of the fibril and the inner void surface. Adsorption device that is an agent.   The organic polymer resin is an adsorbent comprising at least one selected from the group consisting of ethylene vinyl alcohol copolymer (EVOH), polyacrylonitrile (PAN), polysulfone (PS), and polyvinylidene fluoride (PVDF). The adsorption device according to claim 1.   The inorganic ion adsorbent is at least one selected from the group consisting of titanium, zirconium, tin, iron hydrated oxide; titanium, zirconium, tin hydrous ferrite; hydrous cerium, hydrous lanthanum, and activated alumina. The adsorption | suction apparatus as described in any one of Claims 1-2 which comprises these.   A method for treating raw water containing ions using a moving bed type adsorber filled with an adsorbent, wherein the adsorber uses the adsorber according to any one of claims 1 to 3. .

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