JP2008246478A - Adsorbent - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adsorbent which is a composition for environmental cleaning which adsorbs/insolubilizes noxious ions in a solution or a solid, in more definite terms, adsorbs a fluoride ion, a boron iron, a phosphate ion, etc., especially an adsorbent which can efficiently absorb/insolubilize these ions even in case the density is low and for a long time. <P>SOLUTION: This adsorbent adsorbs/insolubilizes the fluoride ion, boron ion and phosphate ion in a solution or a solid, and is composed of a composite oxide particle powder containing a calcium ion, an aluminum ion and an iron ion. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention is an environmental purification composition that adsorbs and insolubilizes harmful ions in a solution or solid. Specifically, it adsorbs fluorine ions, boron ions, phosphate ions, etc., and particularly provides an adsorbent that can be adsorbed and insolubilized over a long period of time even at low concentrations. .

  In recent years, many environmental technologies that adsorb and remove harmful ions in water and soil have been proposed, but they can be efficiently and efficiently loaded with harmful anions such as fluorine ions and boron ions in a wide concentration range. There are currently no known materials that can be processed inexpensively.

  Conventionally, as a method for adsorbing and removing fluorine ions and boron ions in an aqueous solution, it is known to use a chelate resin / chelate fiber or an ion exchange resin.

  However, chelate resins and chelate fibers can efficiently form chelate with fluorine and boron ions to adsorb and remove the ions, but they are expensive and are not materials that can be released into the environment. In addition, ion exchange resins can be selectively exchanged with fluorine or boron ions, but are expensive, so the place of use is limited. Further, ion exchange resins have low removal / adsorption ability with respect to borofluoride ions, and are hardly useful.

  Also, hydrotalcite-type layered compounds and MgO-type composite oxides obtained by heating and dehydrating them can take many types of anions between layers and add water-based anions to be removed and insolubilized. However, since there is a hierarchy in the ease of incorporation, it is not efficient for insolubilization and removal of boron ions and fluorine ions. And since the time that a compound such as a hydrotalcite-type layered compound can exhibit insolubilization / removal ability in an aqueous system is about 24 hours at most, these compounds cannot be used for applications that require continuous insolubilization / removal ability. .

  In addition, the reverse osmosis method, the evaporation method, and the like require a large amount of equipment costs, and the place of implementation is limited.

  Therefore, there is a demand for an adsorbent that is harmless, inexpensive, usable in a wide concentration range, simple and durable.

  Conventionally, a method for removing phosphate ions and ammonium ions in water with a magnesia-based adsorbent (Patent Document 1), and a technique for adsorbing and separating fluoride ion-containing water or boron-containing water in the presence of calcium ions and aluminum ions (patent) Documents 2 to 4), techniques using a composite oxide containing calcium ions or magnesium ions and aluminum ions or iron ions as adsorbents (Patent Documents 5 and 6) are known.

JP-A-53-114791 JP-A-57-27191 JP-A-57-81881 JP 2001-239273 A JP 2002-66548 A JP 2002-136965 A

  Adsorbents that are safe, inexpensive, and have a wide range of adsorption characteristics, simple and long-lasting adsorbents are the most demanded at present, but there is still an adsorbent that meets these requirements. It has not been.

  That is, in the method according to the aforementioned Patent Document 1, the adsorption capacity of the phosphoric acid of the adsorbent is about 0.02 g per 1 g of the adsorbent, which is not a satisfactory level as the adsorption capacity. In the aforementioned Patent Document 2, it is described that wastewater of about 200 mg / L can be reduced to about 1 mg / L as fluorine ions, but it is very complicated such as pH adjustment of wastewater and a multistage process. Processing is required. In addition, this method increases the chlorine ion concentration in addition to fluorine, and the form of use is limited. In the above-mentioned Patent Document 3, it is described that simulated waste water containing about 10 to 500 mg / L as boron ions can be reduced to about 3 mg / L, but the level that can satisfy currently required environmental standards. It's hard to say. In this method, the concentration of sulfate ions is increased in addition to boron, and the form to be used is limited. In the above-mentioned Patent Document 4, it is described that fluorine and boron can be processed at a high level, but it is difficult to say that the level can satisfy the environmental standards currently required. Moreover, since embodiment is complicated, the place to utilize is limited. In the aforementioned Patent Documents 5 and 6, there is described a method of using rock salt type oxides containing magnesium or the like for waste water treatment, but no reference is made to a method for removing low concentrations of fluorine ions and boron ions. Absent. In addition, this method uses a large amount of harmful nitrate ions in the production of the adsorbent, and is not necessarily a recommended production method.

  Therefore, it is difficult to say that the adsorbents / insolubilizers of harmful anions known so far satisfy the currently required level.

  The technical problem can be achieved by the present invention as follows.

  That is, the present invention is an adsorbent that adsorbs and insolubilizes fluorine ions, boron ions and phosphate ions in a solution or a solid, and is a composite oxide particle powder containing calcium ions, aluminum ions and iron ions, When the number of moles of Ca is d, the number of moles of Al is e, and the number of moles of Fe is f, d + e + f = 1, 0.6 ≦ d / (e + f) ≦ 4, 0 <d, 0.02 ≦ e, It is an adsorbent characterized by 0.02 ≦ f (Invention 1).

  Since the adsorbent according to the present invention can adsorb and capture harmful anions in a wide concentration range, it is suitable as a wastewater treatment agent and harmful anion insolubilizing agent. Moreover, since the adsorbent according to the present invention does not require a complicated processing step, it is suitable as an adsorbent used in a simple processing method. Furthermore, the adsorbent according to the present invention is also effective for the adsorption / insolubilization of wastewater in which boron and fluorine coexist.

  Furthermore, since the adsorbent according to the present invention is composed of harmless elements or compounds, the burden on the environment is small even when the adsorbent is disposed of in landfills.

  The configuration of the present invention will be described in more detail as follows.

  First, an adsorbent comprising the composite oxide particle powder according to the present invention (hereinafter referred to as “composite oxide particle powder B”) will be described.

  The complex oxide particle powder B in the present invention is composed of complex oxide particles containing calcium ions, aluminum ions, and iron ions.

  The particle shape of the composite oxide particle powder B in the present invention is plate or granular.

  The average particle size of the composite oxide particle powder B in the present invention is preferably 0.2 to 100 μm. When the average particle size is less than 0.2 μm, the adsorptive power persistence of harmful anions is insufficient. When exceeding 100 micrometers, since the solid-liquid contact area of harmful anion and adsorbent becomes small, it is not preferable. Preferably it is 0.5-50.0 micrometers.

The BET specific surface area value of the composite oxide particle powder B in the present invention is preferably 0.05 to 30 m ² / g, more preferably 0.07 to ²⁰ m ² / g.

  The composition of the oxide particle powder constituting the composite oxide particle powder B in the present invention is as follows.

When the number of moles of Ca is d, the number of moles of Al is e, and the number of moles of Fe is f, the following composition is obtained.
d + e + f = 1, 4 ≧ d / (e + f) ≧ 0.6
d> 0, e ≧ 0.02, f ≧ 0.02

  The d / (e + f) ratio in the composition is more preferably 0.8 to 4.0.

  When it is outside the above composition range, composite oxide particle powder having desired adsorption ability cannot be obtained.

The crystal phase constituting the composite oxide particle powder B is composed of calcium diferrite (2CaO · Fe ₂ O ₃ ), calcium oxide (CaO), Ca ₃ Al ₂ O ₆ , CaAl ₂ O _4, etc. In this case, when a part of aluminum is replaced with iron and is dissolved, a part of iron is replaced with aluminum and is dissolved.

In the present invention, a composite oxide particle A containing magnesium ions, aluminum ions and potassium ions (hereinafter referred to as “composite oxide particle powder B”) together with the composite oxide particle powder B according to the present invention. You may use together.

  The particle shape of the composite oxide particle powder A in the present invention is plate or granular.

  The average particle size of the composite oxide particle powder A in the present invention is preferably 0.1 to 50.0 μm. When the average particle size is less than 0.1 μm, the adsorbing power persistence of harmful anions is insufficient. When it exceeds 50 μm, the solid-liquid contact area between the harmful anion and the adsorbent becomes small, which is not preferable. Preferably it is 0.2-25.0 micrometers.

BET specific surface area value of the composite oxide particles A in the present invention is preferably 0.1~30m ² / g, more preferably 0.2~25m ² / g.

  The composition of the composite oxide particle powder A in the present invention is as follows.

Mg _a · Al _b · K _c O _{(2a + 3b + c) / 2}
a + b + c = 1, 4.0 ≧ a / b ≧ 0.5
a> 0, b> 0, 0.10 ≧ c ≧ 0.005

  The a / b ratio in the composition is more preferably 1.0 to 4.0.

  When it is outside the above composition range, composite oxide particle powder having desired adsorption ability cannot be obtained. When potassium is not included, the adsorption ability decreases when boron ions and fluorine ions coexist.

The crystal phase of the composite oxide particle powder A is of the MgO type.

  Next, a method for producing the composite oxide particle powder B in the present invention will be described.

  The composite oxide particle powder B in the present invention is sufficiently mixed with a calcium compound, an aluminum compound and an iron compound using a dry mixer or a wet mixer, then dried and molded, and oxidized at a temperature of 700 to 1100 ° C. It can be obtained by heat treatment in an oxidizing or non-oxidizing atmosphere. Moreover, a grinding | pulverization process and a dry-type surface treatment can be performed as needed.

  As the calcium compound, calcium hydroxide, calcium carbonate, calcium oxide, calcium nitrate and the like can be used, and calcium hydroxide and calcium carbonate are preferable. The particle size of the calcium compound is preferably 0.2 to 20 μm.

  The aluminum compound is the same as the aluminum compound used in the production of the composite oxide particle powder A.

  As the iron compound, hematite, magnetite, goethite (αFeOOH), iron nitrate and the like can be used, and hematite and goethite are preferable. The particle size of the iron compound is preferably 0.1 to 20 μm.

  Since the mixing state of the mixture which is the precursor of the composite oxide particle powder B in the present invention is important for causing the subsequent solid-phase reaction uniformly and promptly, selection of the mixer and the mixing conditions is also important. . Further, in order to promote the particle growth of the composite oxide powder B during the heat treatment, a potassium salt, a sodium salt, or a lithium salt may be added to the mixed powder before the heat treatment if it is 5 wt% or less with respect to the mixed powder.

  Next, the heat treatment of the precursor (mixture) of the composite oxide particle powder B in the present invention will be described. The heating temperature is preferably 700 to 1100 ° C. at which the solid phase reaction proceeds. A heating temperature of less than 700 ° C. is not preferable because the progress of the dehydration reaction and solid phase reaction of the mixed powder is extremely slow. On the other hand, when the heating temperature exceeds 1100 ° C., the crystallite size of the generated composite oxide particles increases, and the reactivity with harmful anions in the aqueous system decreases, which is not preferable. A particularly preferable heat treatment temperature is 800 to 1000 ° C. In consideration of industrial productivity, the heating time is preferably 15 minutes to 300 minutes. The heating atmosphere may be an oxidizing or non-oxidizing atmosphere. When a large amount of carbonate ions are contained in the heated product particles, the reactivity with harmful anions in the aqueous system is lowered, so heat treatment in carbon dioxide gas is not preferable.

In the present invention, the heat-treated particle powder can be subjected to dry pulverization / dry organic surface treatment, and the treatment method, surface treatment agent and coating amount can be the same as those of the composite oxide particle powder A. it can.

  Next, a method for producing the composite oxide particle powder A in the present invention will be described.

  The composite oxide particle powder A in the present invention is sufficiently mixed with a magnesium compound, an aluminum compound and a potassium compound using a dry mixer or a wet mixer, then dried and molded, and oxidized at a temperature of 300 to 700 ° C. It can be obtained by heat treatment in an oxidizing or non-oxidizing atmosphere. Moreover, a grinding | pulverization process and dry-type organic substance surface treatment can be performed as needed.

  As the mixer in the above production method, a cracker, a hammer mill, a free crusher, a roller mixer, a vibration mill, a bead mill, a disk type wet stirring and mixing tank, and the like can be used.

  As the magnesium compound, magnesium hydroxide, basic magnesium carbonate, magnesium oxide, magnesium nitrate and the like can be used, and magnesium hydroxide and basic magnesium are preferable. The particle size of the magnesium compound is preferably 0.1 to 20 μm.

  As the aluminum compound, boehmite, bayerite, nordstrandite, pseudoboehmite, η alumina, θ alumina, α alumina, aluminum nitrate or the like can be used, and preferably boehmite, bayerite, norstrandite. The particle diameter of the aluminum compound is preferably 0.1 to 20 μm.

  As the potassium compound, potassium hydroxide, potassium carbonate, potassium hydrogen carbonate and the like can be used, and potassium hydroxide and potassium carbonate are preferred.

  Since the mixing state of the mixture which is the precursor of the composite oxide particle powder A in the present invention is important for causing the subsequent solid-phase reaction uniformly and promptly, selection of the mixer and the mixing conditions is important. .

  Next, the heat treatment of the precursor (mixture) of the composite oxide particle powder A in the present invention will be described. The heating temperature is preferably in the temperature range of 300 to 700 ° C. at which the solid phase reaction proceeds. A heating temperature of less than 300 ° C. is not preferable because the progress of the dehydration reaction and solid phase reaction of the mixed powder is extremely slow. On the other hand, when the heating temperature exceeds 700 ° C., the crystallite size of the generated composite oxide particles increases, and the reactivity with harmful anions in the aqueous system decreases, which is not preferable. The heat treatment temperature is more preferably 400 to 600 ° C. In consideration of industrial productivity, the heating time is preferably 15 minutes to 300 minutes. The heating atmosphere may be an oxidizing or non-oxidizing atmosphere. When a large amount of carbonate ions are contained in the heated product particles, the reactivity with harmful anions in the aqueous system is lowered, so heat treatment in carbon dioxide gas is not preferable.

  In the present invention, the powder after the heat treatment may be subjected to dry pulverization / dry surface treatment.

  Since the dry pulverization treatment can reduce the average particle size of the powder after the heat treatment, the reactivity of the powder of the present invention with harmful anions in the aqueous system can be improved. As an apparatus that can be used for the dry pulverization treatment, a free pulverizer, a hammer mill, or the like can be used.

  In addition, by subjecting the powder after the heat treatment to a dry surface treatment with an organic substance or the like, the reactivity with harmful anions in the aqueous system can be controlled. Examples of the surface treatment agent include rosin compounds, silane coupling agents, higher fatty acids and the like. The coating amount on the adsorbent powder by the surface treatment agent is preferably 0.1 to 5% by weight in terms of C with respect to the composite oxide particle powder. As a dry surface treatment machine, a rough machine, a vibration mill, a roller type mixer, or the like can be used.

  In the present invention, the composite oxide particle powder A and the composite oxide particle powder B may be mixed and used.

  The mixing ratio of the composite oxide particle powder A and the composite oxide particle powder B preferably contains 10 to 90% by weight of the adsorbent A with respect to the adsorbent after mixing.

  The mixing method of the composite oxide particle powders A and B may be mixed after adding the composite oxide particle powders A and B to the liquid to be processed and the object to be processed, or added to the liquid and object to be processed. The composite oxide particle powders A and B may be previously dry mixed with a mixer in advance. As the dry mixer, a Henschel mixer, a raker, etc. can be used.

  Next, a method for treating dissolved harmful anions using the adsorbent according to the present invention will be described.

  The harmful anion treatment step in the present invention is carried out by immobilizing / separating dissolved harmful anions and releasing harmful anions into the water system by coexisting an adsorbent with substances that may release harmful anions. A distinction is made when it is suppressed. Hereinafter, the treatment process of dissolved harmful anions (coexistence of fluorine ions and boron ions) in the present invention will be described.

  In the present invention, the method for bringing the water to be treated into contact with the adsorbent is not particularly limited. A method in which water to be treated is circulated through a column or filtration tank filled with an adsorbent and / or an adsorbent granule, a method in which a stirring tank and a precipitation tank are combined, and the like can be used.

  Although there is no restriction | limiting in particular about the liquid temperature at the time of making an adsorbent contact, in the case of low temperature, since the hydration reaction rate of an adsorbent becomes small, the capture | acquisition rate of a harmful anion becomes small. The temperature range usually used is 5 to 90 ° C, preferably 10 to 50 ° C. The contact time between the adsorbent and the liquid to be treated is preferably 5 minutes or longer, more preferably 30 minutes or longer. The upper limit of the contact time is not particularly limited, but it is preferable to avoid contact between the high concentration carbon dioxide gas and the liquid to be treated as much as possible.

  When adsorbents A and B are used at the same time, either adsorbents A and B may be mixed in advance, or adsorbents A and B may be added at the time of addition.

<Action>
The important point in the present invention is that the composite oxide particle powder according to the present invention has the ability to undergo a hydration reaction when it comes into contact with an aqueous solution, and can capture low to high concentrations of harmful anions.

In the present invention, in the harmful anion treatment step, calcium-iron-aluminum that is a constituent phase of the potassium ion-containing rock salt type particles and the composite oxide particle powder B, which are constituent phases of the composite oxide particle powder A, in the liquid to be treated. Some of the reactions shown below occur in the presence of harmful anions (coexistence of fluorine ions and boron ions) with solid solution particles (Fe solid solution Ca ₃ Al ₂ O _6, Al solid solution calcium diferrite, etc.) and CaO particles. I think it will happen.

Hydration reaction of composite oxide particle powder A Mg _a · Al _b · K _c O _{(2a + 3b + c) / 2} + αH ₂ O
+ (A + b) NaF + (a + b) Na ₂ B ₄ O ₇
→ [Mg _a Al _b (OH) _{2 (a + b)} ] [b (OH) · βH ₂ O]
+ (A + b) KBF ₄ +3 (a + b) NaOH (1)
α and β are numbers greater than or equal to 0.
Hydration of composite oxide particles _{B Ca d · Al e · Fe} f O (2d + 3e + 3f) / 2 + γH 2 O
+1/2 (e + f) Na ₂ B ₄ O ₇
→ _{[Ca d Al e Fe f (OH} ) 2 (d + e + f) ] _{[1/2 (e + f) (B} 4 O 7) · δH 2 O ] + 1/2 (e + f) NaOH ··· (2)
γ and δ are numbers greater than or equal to 0.

  The above reactions (1) and (2) are so-called hydration reactions. When the oxide hydrates with the liquid to be treated, the dissolved anions are taken in between the generated particles, and the dissolved anions in the liquid to be treated are removed. Decrease. In the case of the present invention, the hydration reaction of (1) proceeds promptly, but the hydration reaction of (2) proceeds more slowly than the reaction of (1). Therefore, the adsorbent of the present invention continues the adsorption capacity for a long time because the hydration reaction proceeds for a long time. Further, since the hardly soluble compound shown in the second term of the reaction (1) is generated, it is particularly effective for the adsorption / insolubilization treatment of a liquid in which fluorine ions and boron ions coexist.

  The composite oxide particle powder A according to the present invention is an MgO-type oxide in which aluminum ions are solid solution, and has the ability to rapidly hydrate when contacted with an aqueous solution. However, the adsorbent B contains calcium ions and aluminum ions. Since the iron ion has the ability to hydrate and react slowly in an aqueous solution, there are many opportunities for the harmful anion to come into contact with the adsorbent, so that the present inventor can capture a low concentration to a high concentration of the harmful anion. Is estimating.

  Therefore, compared with the case where a calcium compound, an aluminum compound, and a magnesium compound are used individually, dissolved anions can be more adsorbed.

  In addition, the important point in the present invention is that the cations contained in the adsorbents A and B according to the present invention are magnesium ions, aluminum ions, potassium ions, calcium ions and iron ions, so they are inexpensive and released into the environment. Even so, the problem is extremely small.

  In addition, an important point in the present invention is that the adsorbent can be recycled by bringing the adsorbent capturing toxic anions into contact with a carbonate ion-containing solution or the like.

  Further, in the present invention, the particle size and shape of the adsorbent according to the present invention is excellent in kneadability with a general-purpose resin and a biodegradable resin, so that a composite of resin and adsorbent can be produced. is there. By being able to form a composite of an adsorbent and a resin, it is possible to arbitrarily control the life of the adsorbent and the shape and size of the adsorbent. That is, when the complex of resin and adsorbent is brought into contact with an aqueous solution, harmful anions in the aqueous solution can be captured and insolubilized for an extremely long time.

  A typical embodiment of the present invention is as follows.

  The average particle diameter of the composite oxide particle powder is indicated by the average value of the numerical values measured from the electron micrograph.

  The identification of the crystal phase of the composite oxide particle powder is “X-ray diffractometer RAD-2A (manufactured by Rigaku Corporation)” (tube: Fe, tube voltage: 40 kV, tube current: 20 mA, goniometer: wide angle goniometer. Meter, sampling width: 0.010 °, scanning speed: 0.500 ° / min, divergence slit: 1 °, scattering slit: 1 °, light receiving slit: 0.30 mm).

  The BET specific surface area value was shown as a value measured by the BET method.

  The composition analysis of metal ions of the composite oxide particle powder in the present invention was obtained by dissolving the powder with hydrochloric acid and measuring with “Plasma emission spectroscopic analyzer SPS4000 (Seiko Electronics Co., Ltd.)”. The carbon content (% by weight) of the composite oxide particle powder was measured by a carbon sulfur analyzer: EMIA-2200 (manufactured by HORIBA).

Adsorbent adsorption test Phosphate ions The measurement method for the phosphate ion adsorption capacity of the prepared adsorbent will be described.
1.0 g of adsorbent is added to 400 mL of an aqueous NaH ₂ PO ₄ solution (about pH 4.4) adjusted to 2000 ppm as an element P for phosphate ions, stirred with a stirrer for 2 hours, and then from the aqueous solution. The suspended particles were filtered off with a filter paper, and the phosphate ion concentration in the filtrate was determined by ICP.

Adsorbent adsorption test borate ion The measurement method regarding the borate ion adsorption capacity of the prepared adsorbent will be described.
0.5 g of an adsorbent was added to 500 mL of an aqueous Na ₂ B ₄ O ₇ solution (the pH was adjusted to about 12.0 by adding NaOH) in which the boron ion content was adjusted to 100 ppm as element B. After stirring with a stirrer, suspended particles were filtered from the aqueous solution with a filter paper, and the borate ion concentration in the filtrate was determined by ICP.

Adsorption test of adsorbent borate ion / fluorine ion mixture The measurement method of boric acid ion and hydrofluoric acid ion mixed adsorption ability of the prepared adsorbent will be described.
A borate ion / fluorine ion mixed aqueous solution prepared by adjusting 0.5 g of the adsorbent to a boron ion content of 5 ppm as element B (using Na ₂ B ₄ O ₇ ) and a fluorine ion content of 30 ppm (using NaF) as element F Add to 500 mL (pH adjusted to about 12.0 using NaOH), stir with a stirrer for 2 hours, then filter off suspended particles from the aqueous solution with filter paper, and adjust the borate ion concentration in the filtrate. This was performed by quantifying fluorine ions by ion chromatography using ICP.

<Reference Example 1: Production of composite oxide particle powder A>
A cylindrical stainless steel container having an internal volume of 2.5 l is charged with 1.0 l of an 8 mol / L sodium hydroxide aqueous solution and kept at 60 ° C. while stirring the system. To this was added 1.5 l of a 2.0 mol / L magnesium sulfate aqueous solution, and the mixture was aged at a pH value of 13.5 and 95 ° C. for 5 hours while stirring in the reaction vessel to form a white precipitate. A part of the obtained white precipitate was taken out, filtered, washed with water and dried, and then identified by X-ray diffraction. As a result, it was confirmed to be magnesium hydroxide. Next, the aqueous suspension containing the white precipitate is cooled to room temperature, decanted with ion-exchanged water, the pH value is lowered to 10.0, and a total suspension of 1.6 l is obtained. 0.5 L of a slurry containing 78 g of Sumitomo Chemical's aluminum hydroxide powder C-301 is added to the suspension, and the mixture is kept at 30 ° C. for 2 hours while stirring in a container. After completion of the holding, filtration and washing with water were followed by drying at 60 ° C. to obtain hydroxide mixed particle powder.

After mixing 30 g of the obtained hydroxide mixed particle powder and 0.3 g of potassium hydroxide (special grade of Yoneyama Pharmaceutical Co., Ltd.) with an alumina cracker, the mixture was placed in an alumina crucible and heated at 500 ° C. for 2 hours at a muffle furnace (air Medium). After the heat treatment, the crucible was taken out, cooled in air for 30 minutes, and immediately stored in a highly airtight polyethylene container. A part of the obtained white oxide was taken out and identified by X-ray diffraction. As a result, it was confirmed that the crystal phase had a magnesium oxide type structure. As a result of ICP composition analysis, it was found that the metal ion content was 74 mol% magnesium, 25 mol% aluminum, and 1 mol% potassium. Therefore, the ratio was almost the same as the charged composition. Moreover, the average plate | board surface diameter of the obtained oxide particle powder was 1.2 micrometers, and the BET specific surface area value was 13 m < ² > / g.

Phosphate ion adsorption treatment Using the adsorbent A obtained here, treatment of phosphate ion-containing water was performed according to the above method, and 2000 ppm of phosphorus contained in the liquid to be treated was reduced to 950 ppm. The adsorption amount was 0.42 g per 1 g of the adsorbent. The pH after the treatment was 12.3.

<Example: Production of adsorbent B>
Put 1.5 L of pure water into a cylindrical stainless steel container with an inner volume of 2.5 L, and further 65 g of heavy calcium carbonate powder (Maruo Calcium Super SSS) (average particle size 2.0 μm) and hematite for pigment (120ED made by Toda Kogyo) ) 20 g (average particle size 0.15 μm) and 7.8 g (average particle size 1.0 μm) of aluminum hydroxide powder C-301 manufactured by Sumitomo Chemical Co., Ltd. were kept for 5 hours while stirring in the reaction vessel. Then, after filtering, washing with water, and drying, the mixed particle powder was obtained by drying at 60 degreeC.

30 g of the obtained mixed particle powder was put in an alumina crucible and heated in a muffle furnace (in air) at 1000 ° C. for 2 hours. After the heat treatment, the crucible was taken out, cooled in air for 30 minutes, and immediately stored in a highly airtight polyethylene container. As a result of taking out a part of the obtained light blue oxide and identifying it by X-ray diffraction, it was confirmed that it was a mixture of calcium oxide type structured particles, calcium diferrite type particles, and Ca ₃ Al ₂ O ₆ type particles. . As a result of composition analysis by ICP, it was found that the content ratio of metal ions was 63.5 mol% calcium, 25.8 mol% iron, and 10.7 mol% aluminum. Therefore, it was confirmed that the ratio was almost the same as the charged composition. Further, it is suggested by X-ray diffraction that iron ions and aluminum ions are dissolved in Ca ₃ Al ₂ O ₆ type particles and calcium diferrite type particles, respectively. Moreover, the average plate | board surface diameter of the obtained oxide particle powder was 1.2 micrometers, and the BET specific surface area value was 2.1 m < ² > / g.

Borate ion adsorption treatment Using the adsorbent B obtained here, borate ion-containing water was treated according to the above-described method. As a result, 100 ppm of boron contained in the liquid to be treated was reduced to 53 ppm. The amount adsorbed was 0.047 g / g adsorbent. The pH after treatment was 12.4.

Examples 1-5, Reference Examples 1-6
A composite oxide particle powder was obtained in the same manner as in the above <Manufacture of adsorbent>, except that various types, amounts, mixing methods, heating temperatures, and heating times of various metal compounds were changed.

Tables 1 and 2 show the powder characteristics and adsorption characteristics of the adsorbents obtained.
The crystal phases in Table 2 are A: MgO, B: Ca ₃ Al ₂ O ₆ (including Fe solid solution), C: CaAl ₂ O ₄ (including Fe solid solution), D: hematite, E: CaCO ₃ , respectively. F: CaO, G: Mg (OH) ₂ , H: Nordstrandite, I: Calcium diferrite (including Al solid solution), J: Alumina.

Comparative Examples 1-6
For comparison, composite oxide particle powders were obtained in the same manner as in the above <Manufacture of adsorbent>, except that various types, amounts, mixing methods, heating temperatures, and heating times of various metal compounds were changed.

  As a result of ICP analysis, it was found that the composition of the obtained composite oxide particle powder was approximately the same as the charged composition.

  Since the adsorbent according to the present invention can adsorb and capture harmful anions in a wide concentration range, it is suitable as a wastewater treatment agent and harmful anion insolubilizing agent. Moreover, since the adsorbent according to the present invention does not require a complicated processing step, it is suitable as an adsorbent used in a simple processing method. Furthermore, the adsorbent according to the present invention is also effective for the adsorption / insolubilization of wastewater in which boron and fluorine coexist.

Furthermore, since the adsorbent according to the present invention is composed of harmless elements or compounds, the burden on the environment is small even when the adsorbent is disposed of in landfill.

Claims (1)

An adsorbent that adsorbs and insolubilizes fluorine ions, boron ions, and phosphate ions in a solution or solid, and is a composite oxide particle powder containing calcium ions, aluminum ions, and iron ions, wherein the number of moles of Ca is d When the number of moles of Al is e and the number of moles of Fe is f, d + e + f = 1, 0.6 ≦ d / (e + f) ≦ 4, 0 <d, 0.02 ≦ e, 0.02 ≦ f An adsorbent characterized by being.