WO2020017538A1 - Inorganic ion exchanger, method for producing same and method for purifying water containing radioactive strontium - Google Patents

Inorganic ion exchanger, method for producing same and method for purifying water containing radioactive strontium Download PDF

Info

Publication number
WO2020017538A1
WO2020017538A1 PCT/JP2019/028032 JP2019028032W WO2020017538A1 WO 2020017538 A1 WO2020017538 A1 WO 2020017538A1 JP 2019028032 W JP2019028032 W JP 2019028032W WO 2020017538 A1 WO2020017538 A1 WO 2020017538A1
Authority
WO
WIPO (PCT)
Prior art keywords
ion exchanger
inorganic ion
alkali metal
powder
strontium
Prior art date
Application number
PCT/JP2019/028032
Other languages
French (fr)
Japanese (ja)
Inventor
裕延 沖
飯田　正紀
義之 佐野
前川　文彦
Original Assignee
Dic株式会社
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Dic株式会社 filed Critical Dic株式会社
Priority to JP2020531334A priority Critical patent/JP7400716B2/en
Publication of WO2020017538A1 publication Critical patent/WO2020017538A1/en

Links

Images

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J39/00—Cation exchange; Use of material as cation exchangers; Treatment of material for improving the cation exchange properties
    • B01J39/08—Use of material as cation exchangers; Treatment of material for improving the cation exchange properties
    • B01J39/09—Inorganic material
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
    • G21F9/00—Treating radioactively contaminated material; Decontamination arrangements therefor
    • G21F9/04—Treating liquids
    • G21F9/06—Processing
    • G21F9/12—Processing by absorption; by adsorption; by ion-exchange

Definitions

  • the present invention relates to an inorganic ion exchanger and a method for producing the same.
  • the present invention also relates to a method for purifying water containing radioactive strontium, using the inorganic ion exchanger.
  • alkali metal titanate compounds are ionized. Methods have been proposed for use as exchangers.
  • the alkali metal titanate compound used as the ion exchanger include a layered structure alkali metal titanate having a TiO 5 triangular bipyramidal chain structure and a layered alkali metal titanate having a TiO 6 octahedral chain structure.
  • Patent Document 1 a silicic acid source, a sodium and / or potassium compound, titanium tetrachloride, and water are mixed to obtain a mixed gel, and the mixed gel is obtained by a hydrothermal reaction.
  • Crystalline silico titanates Patent Document 2 and the like are known.
  • As an alkali metal titanate compound potassium tetratitanate K 2 Ti 4 O 9 is known to be able to exchange potassium ions for calcium ions by taking in water between crystal layers (Non-Patent Document 1).
  • the conventional method using a synthetic zeolite-based adsorbent or a cation exchange resin or the conventional method using an alkali metal titanate compound as an ion exchanger has a problem that the ability to remove radioactive strontium is not sufficient.
  • the problem to be solved by the present invention is to use an inorganic ion exchanger capable of removing radioactive strontium until the radioactive strontium falls below a reference value, a method for producing the inorganic ion exchanger, and using the inorganic ion exchanger.
  • Another object of the present invention is to provide a method for purifying water containing radioactive strontium.
  • the present inventor has found that an inorganic ion exchanger containing a layered titanate containing at least one selected from the group consisting of an alkali metal salt and an alkali metal carbonate in a crystal structure has high ion exchange ability, The present inventors have found that radioactive strontium can be removed from water containing radioactive strontium with high efficiency, and have completed the present invention.
  • the present invention relates to the following [1] to [10].
  • the layered titanate is, xA 2 O ⁇ TiO 2 ⁇ yH 2 O ⁇ zA 2 CO 3 (A represents Li, K, Na, at least one element selected from Rb and Cs, x, y and z are respectively represented by 0.02 ⁇ x ⁇ 2.0, y ⁇ 0.05 and z ⁇ 0.015).
  • the inorganic ion exchange according to [1], wherein body.
  • the layered titanate has a diffraction peak having a maximum point in a range of a diffraction angle (2 ⁇ ) of 1 ° or more and 8 ° or less in a powder X-ray diffraction pattern measured using CuK ⁇ radiation.
  • a diffraction angle (2 ⁇ ) of 1 ° or more and 8 ° or less in a powder X-ray diffraction pattern measured using CuK ⁇ radiation.
  • Kd Qeq / Ceq (1)
  • Kd is the partition coefficient (ml / g)
  • Ceq is the strontium concentration in the aqueous solution when the equilibrium is reached (mol / ml)
  • Qeq is strontium per unit weight of the inorganic ion exchanger when the equilibrium is reached. (Denotes the adsorption amount (mol / g), respectively)
  • [6] The method for producing an inorganic ion exchanger according to any one of [1] to [5], wherein the following steps (1) and (2) are sequentially performed. How to make exchangers.
  • Step (1) mixing the titanium compound powder with an excess amount of at least one powder selected from the group consisting of alkali metal carbonates and alkali metal bicarbonates
  • Step (2) the step (1) [7] a step of heating the mixture obtained in the above at a temperature of 700 ° C. or more and 1500 ° C. or less, wherein the following steps (3) and (4) are sequentially performed. Production method.
  • Step (3) a step of washing the inorganic ion exchanger obtained in the step (2) with water
  • Production method. [9] The method for producing an inorganic ion exchanger according to any one of [6] to [8], wherein in the step (1), a powder of an alkali metal sulfate is further mixed.
  • the inorganic ion exchanger of the present invention has a high ion exchange capacity and can remove radioactive substances from water containing radioactive substances with high efficiency. For this reason, when removing a radioactive substance from a radioactive waste liquid, the amount used as an inorganic ion exchanger can be reduced, the purification cost can be reduced, and the amount of radioactive waste can be reduced. Further, the inorganic ion exchanger of the present invention can be used for removing heavy metals from well water, recovering valuable resources from seawater, and removing harmful substances from contaminated soil.
  • 3 is a powder X-ray diffraction pattern of the layered titanate obtained in Example 1.
  • 3 is a 13 C-NMR spectrum of the layered titanate obtained in Example 1.
  • the inorganic ion exchanger of the present invention contains, in its crystal structure, a layered titanate containing at least one selected from the group consisting of alkali metal carbonates and alkali metal bicarbonates.
  • alkali metal carbonate contained in the crystal structure of the layered titanate include, for example, lithium carbonate, sodium carbonate, potassium carbonate, rubidium carbonate, cesium carbonate, and the like. Or two or more of them may be contained in combination.
  • Examples of the alkali metal bicarbonate contained in the crystal structure of the layered titanate include, for example, lithium bicarbonate, sodium bicarbonate, potassium bicarbonate, rubidium bicarbonate, cesium bicarbonate, and the like. May be contained alone or in combination of two or more.
  • the form of the inorganic ion exchanger of the present invention is not particularly limited, and examples thereof include powder, granules, particles, columns, spheres, pellets, honeycomb molded bodies, and porous molded bodies. , Alumina, zirconia, cordierite or the like may be supported on a support. Since the ion exchanger is generally used in a method of packing a column and passing a radioactive waste liquid or the like, the ion exchanger is in the form of granules or particles having a size of about 1 mm and is fragile even if it is in contact with water for a long time. It is preferable that the form is not changed.
  • xA 2 O ⁇ TiO 2 ⁇ yH 2 O ⁇ zA 2 CO 3 (A is Li, K, Na, at least one selected from Rb and Cs X, y, and z each represent a numerical value of 0.02 ⁇ x ⁇ 2.0, y ⁇ 0.05, and z ⁇ 0.015).
  • x is preferably 0.05 ⁇ x ⁇ 1.0, and more preferably 0.1 ⁇ x ⁇ 0.5.
  • y is preferably 0.05 ⁇ y ⁇ 3.0, and more preferably 0.1 ⁇ y ⁇ 2.0.
  • z is preferably 0.015 ⁇ z ⁇ 1.5, and more preferably 0.02 ⁇ z ⁇ 1.0.
  • the zA 2 CO 3 may be zAHCO 3 , and the hydrogen ion in this case is obtained from yH 2 O. Therefore, if the said zA 2 CO 3 is ZAHCO 3, the layered titanate, xA 2 O ⁇ TiO 2 ⁇ (y-z) H 2 O ⁇ zAHCO 3 ⁇ zAOH (A is Li, K, Na , Rb and Cs represent at least one element selected from the group consisting of x, y and z, each of which represents a value of 0.02 ⁇ x ⁇ 2.0, y ⁇ 0.05 and z ⁇ 0.015); Become.
  • the layered titanate has a diffraction point (2 ⁇ ) having a maximum point in a range of 1 ° or more and 8 ° or less, preferably 2 ° or more and 7 ° or less in a powder X-ray diffraction pattern measured using CuK ⁇ radiation. It preferably has a peak.
  • the distance is 1.1 nm to 8.8 nm, preferably 1.3 nm to 4.4 nm.
  • the diffraction angle (2 ⁇ ) of the diffraction peak can be calculated from a diffraction pattern obtained by correcting a diffraction peak pattern obtained by actual powder X-ray diffraction with a baseline.
  • This baseline correction can be performed by fitting a background curve obtained from a compound having no diffraction peak in the diffraction angle range to be calculated.
  • the layered titanate has low crystallinity in which the half value width of the diffraction peak is 3 ° or more at 2 ⁇ . As the half width of the diffraction peak increases, the crystallinity decreases, and as the half width of the diffraction peak decreases, the crystallinity increases.
  • the layered titanate in the present invention is preferably a low crystalline compound having a half value width of the diffraction peak of 3 ° or more at 2 ⁇ , more preferably a low crystalline compound of 3 ° or more and 10 ° or less. .
  • the half width of the diffraction peak can be calculated from the diffraction pattern obtained by correcting the diffraction peak pattern obtained by actual powder X-ray diffraction with a baseline. This baseline correction can be performed by fitting a background curve obtained from a compound having no diffraction peak in the diffraction angle range to be calculated.
  • the half width can be obtained after peak separation. Peak separation can be performed by approximating Gaussian basic waveforms by superimposition and performing curve fitting on each of the overlapping peaks.
  • the inorganic ion exchanger of the present invention contains at least one selected from the group consisting of alkali metal carbonates and alkali metal bicarbonates in the crystal structure of the layered titanate. It has a structure in which the interlayer distance between titanic acids is widened by the intervening carbonate or alkali metal bicarbonate.
  • a conventional inorganic ion exchanger containing a layered titanate has a structure containing water molecules between layers of titanic acid, and the interlayer distance between titanic acids is widened.
  • the inorganic ion exchanger of the present invention can further incorporate water molecules into the crystal structure. That is, the inorganic ion exchanger of the present invention includes those containing water molecules and at least one selected from the group consisting of alkali metal carbonates and alkali metal bicarbonates in the crystal structure of the layered titanate. I do. When containing both water molecules and at least one selected from the group consisting of alkali metal carbonates and alkali metal bicarbonates, only water molecules or from the group consisting of alkali metal carbonates and alkali metal bicarbonates It can be expected that the technical effects of the present invention will be exhibited synergistically as compared with the case where only at least one selected type is included.
  • Partition coefficient of inorganic ion exchanger When the inorganic ion exchanger of the present invention is dispersed in an aqueous solution containing strontium, the alkali metal in the inorganic ion exchanger undergoes an exchange reaction with strontium in the aqueous solution, strontium is incorporated into the inorganic ion exchanger, and strontium is incorporated. Inorganic ion exchangers can be formed. This reaction is an equilibrium reaction represented by the following formula. The more the equilibrium is inclined toward the side of strontium incorporation (to the right), the higher the amount of strontium incorporation can be.
  • A represents an alkali metal
  • IEX represents an inorganic ion exchanger
  • the strontium uptake capacity of the inorganic ion exchanger can be represented by a partition coefficient Kd represented by the following formula (1) when the inorganic ion exchanger is dispersed in an aqueous alkaline strontium solution having a pH of 12 or more.
  • Kd Qeq / Ceq (1)
  • Kd is the partition coefficient (ml / g)
  • Ceq is the strontium concentration (mol / ml) in the solution when the equilibrium reaction is reached
  • Qeq is the inorganic ion when the equilibrium is reached in the equilibrium reaction.
  • the inorganic ion exchanger of the present invention is dispersed in an aqueous solution containing strontium, and then the strontium concentration in the aqueous solution is measured, and the time is determined by determining the time at which the change in the concentration stops. But usually for 3-5 hours.
  • the partition coefficient Kd of the inorganic ion exchanger of the present invention is preferably at least 30,000 ml / g, more preferably at least 100,000 ml / g, even more preferably at least 500,000 ml / g.
  • the higher the partition coefficient Kd the more the equilibrium is inclined toward the strontium incorporation side (right side), and the higher the strontium incorporation ability.
  • the partition coefficient Kd of the inorganic ion exchanger of the present invention since the partition coefficient Kd of the inorganic ion exchanger of the present invention is high, it has a high strontium uptake ability.
  • strontium adsorption a phenomenon in which an ion exchanger takes in strontium by ion exchange.
  • the inorganic ion exchanger of the present invention can be produced by sequentially performing the following steps (1) and (2).
  • a titanium compound powder and an excess amount of at least one kind of powder (hereinafter, also referred to as an alkali metal carbonate or the like) selected from the group consisting of alkali metal carbonates and alkali metal bicarbonates are mixed.
  • the amount of the powder of the alkali metal carbonate or the like mixed with the powder of the titanium compound is not particularly limited as long as it is more than the amount of the powder of the titanium compound. Is preferably, more preferably, 150 mol% or more, and further preferably, 200 mol% or more.
  • the alkali metal carbonate and alkali metal bicarbonate used in the method for producing an inorganic ion exchanger of the present invention include the above-mentioned alkali metal carbonate and alkali metal bicarbonate.
  • Examples of the titanium compound used in the method for producing an inorganic ion exchanger of the present invention include titanium oxide, metatitanic acid, alkali metal titanate, and metal titanium. These may be used alone or may be used alone. A combination of more than one species may be used.
  • Examples of the alkali metal titanate include lithium titanate, sodium titanate, potassium titanate, rubidium titanate, and cesium titanate.
  • the reaction in the alkali metal carbonate melted at a high temperature in the step (2) Precipitation of the titanium compound and uneven reaction are suppressed.
  • the compound after the reaction and the melt of the excess alkali metal carbonate are cooled in a state of being immersed in the alkali metal sulfate powder, so that they are solidified and shrunk when they are shrunk. A gap is formed at the interface with the container, and the product obtained in the step (2) can be easily taken out of the production container.
  • the alkali metal sulfate is not particularly limited, and includes, for example, potassium sulfate and sodium sulfate.
  • Step (2) is a step of heating the mixture obtained in the above step (1) at a temperature of 700 ° C. or more and 1500 ° C. or less.
  • the heating time is preferably 30 minutes to 100 hours.
  • the titanium compound reacts with the alkali metal carbonate to generate a layered titanate.
  • An alkali metal carbonate can be contained in the crystal structure of the layered titanate.
  • the alkali metal bicarbonate is decomposed at a high temperature to become an alkali metal carbonate.
  • the container and the device used for heating have a structure and a mechanism capable of efficiently exhausting carbon dioxide gas.
  • the container preferably has a cutout for ventilation
  • the heating device preferably has a mechanism for sucking the exhaust gas and taking in the outside air little by little.
  • the alkali metal bicarbonate is formed by reacting a part of the alkali metal carbonate contained in the crystal structure in step (2) with water molecules and carbon dioxide supplied from the air or the like. It is.
  • the inorganic ion exchanger obtained in this manner is an inorganic ion exchanger containing a layered titanate containing no water molecule in the crystal structure.
  • the inorganic ion exchanger of the present invention further performs the following steps (3) and (4) in order to produce an inorganic ion exchanger containing a layered titanate further containing a water molecule in the crystal structure. be able to.
  • Step (3) a step of washing the inorganic ion exchanger obtained in the step (2) with water
  • Step (4) a step of drying the inorganic ion exchanger after the washing in the step (3)
  • the step (3) is a step of washing the inorganic ion exchanger obtained in the step (2) with water to remove excess alkali metal carbonate outside the crystal structure of the inorganic ion exchanger.
  • excess alkali metal carbonate outside the crystal structure of the inorganic ion exchanger is removed, and at the same time, the crystal structure of the layered titanate is removed. Water molecules are taken into the inside, and the interlayer distance of the titanic acid is further increased.
  • the product obtained in the step (2) is preferably pulverized before the step (3).
  • a crusher a jaw crusher, a roll crusher, a hammer mill, or the like can be used.
  • the washing with water is preferably gentle so that the alkali metal carbonate and the like existing in the crystal structure of the ion exchanger are not removed. That is, by washing with an appropriate amount of water or washing with non-high-temperature water, more water molecules can be retained in the crystal structure.
  • washing with water involves slurrying with water at room temperature 3 to 10 times the weight of the product of step (2), then dewatering, and then 3% on the weight of the resulting dewatered cake. It is preferable to use a method of passing water of normal temperature having a weight of up to 10 times, or a method of repeating the slurrying and dehydration two to three times.
  • the step (4) is a step of drying the inorganic ion exchanger after the washing in the step (3). It may be possible to completely remove only water molecules and leave only alkali metal carbonates and the like in the crystal structure, but it is preferable to leave not only alkali metal carbonates and the like but also water molecules in the crystal structure. However, as compared with leaving only the alkali metal carbonate or the like in the crystal structure, the interlayer of the titanic acid can be made wider, and the technical effects of the present invention can be maximized. Therefore, in order to allow the water molecules incorporated in the crystal structure of the layered titanate in the step (3) to remain in the crystal structure even after the inorganic ion exchanger is dried in the step (4), The drying conditions are preferably mild.
  • step (3) and the step (4) a part of the water molecule taken into the crystal structure, a part of the alkali metal carbonate present in the crystal structure, and the water are supplied from water or air. Reacts with the carbon dioxide to form alkali metal bicarbonate.
  • the dried product of the inorganic ion exchanger obtained in the step (4) can be pulverized or pulverized to a powder as required. Further, the obtained powder of the inorganic ion exchanger may be subjected to a granulation treatment using a granulation aid to form a granulated body.
  • a granulation aid to form a granulated body.
  • the rolling granulation method fluidized bed granulation method, mixing stirring granulation method, extrusion granulation method, melt granulation method, spray granulation method, compression granulation method, A pulverization granulation method and the like can be mentioned.
  • the granulation aid examples include clay minerals such as bentonite, attapulgite, sepiolite, allophane, halloysite, imogolite, kaolinite; sodium silicate, calcium silicate, magnesium silicate, sodium metasilicate, calcium metasilicate, and metasilicate.
  • Silicate compounds such as magnesium, sodium metasilicate aluminate, calcium metasilicate aluminate, magnesium metasilicate aluminate; organic polymers such as polyvinyl alcohol, carboxymethyl cellulose, sucrose fatty acid ester, butadiene-styrene latex, and fluororesin Is mentioned. These may be used alone or in a combination of two or more.
  • the inorganic ion exchanger of the present invention uses the inorganic ion exchanger of the present invention, water containing a radioactive substance, specifically, water containing radioactive strontium can be purified, and radioactive strontium contained in the water can be removed.
  • the method for purifying water containing radioactive strontium includes a step of contacting water containing radioactive strontium with the inorganic ion exchanger of the present invention, and a step of separating the inorganic ion exchanger from water obtained after the contact. It can be carried out by performing it sequentially.
  • the method of contacting water containing radioactive strontium with the inorganic ion exchanger of the present invention is not particularly limited, for example, the inorganic ion exchanger may be a column or the like. Examples include a method of filling a container and passing water containing radioactive strontium, and a method of dispersing the inorganic ion exchanger of the present invention in water containing radioactive strontium.
  • the method for separating the inorganic ion exchanger from water obtained after contacting the water containing radioactive strontium with the inorganic ion exchanger of the present invention comprises the inorganic ion exchanger of the present invention.
  • the inorganic ion exchanger can be separated from water obtained after contacting water containing radioactive strontium with the exchanger.For example, by filling the inorganic ion exchanger into a container such as a column, the radioactive strontium is added.
  • the passed water When passing the containing water, the passed water may be fractionated as it is, and when the inorganic ion exchanger of the present invention is dispersed in the water containing radioactive strontium, the dispersed inorganic ion exchanger is used. Separating the inorganic ion exchanger from the contacted water using a container having a strainer structure at the top or bottom, etc. It can be carried out more.
  • ⁇ Metal element composition analysis> Using a mixed acid of hydrofluoric acid, nitric acid, and perchloric acid, the sample is decomposed by heating to 140 ° C. in a pressure-resistant sealed container made of Teflon (registered trademark) to form a nitric acid solution, and then containing a metal element by ICP-MS. The amount was analyzed.
  • Example 1 27.6 g of anhydrous potassium carbonate powder (400 mmol as K), 35 g of potassium sulfate powder and 8.0 g of anatase-type titanium dioxide powder (100 mmol as Ti) are well mixed in a mortar, put in an alumina crucible and placed at 950 ° C. for 20 minutes. Heated for hours. The product was coarsely crushed in a mortar, suspended in 500 g of deionized water and stirred for 1 hour. Next, the mixture was filtered under reduced pressure to form a dehydrated cake, and rinsed with 100 g of deionized water while continuing filtration under reduced pressure.
  • the obtained white powder was subjected to the powder X-ray diffraction measurement, and the diffraction pattern shown in FIG. 1 was obtained.
  • a broad peak having a maximum point at a diffraction angle of 8 ° or less was observed, suggesting a structure in which the layers of the layered material were irregularly spread.
  • the peak position of the lowest angle diffraction line was 6.8 °, and the half value width was 5.2 ° at 2 ⁇ .
  • the obtained white powder was subjected to the TG-MS analysis. As a result, the weight was reduced by 13%, and the generated gas was identified as H 2 O.
  • the obtained white powder was analyzed by 13 C-NMR, a chart shown in FIG.
  • Table 1 shows the results of the above analysis. From the results shown in Table 1, the white powder obtained above is a low-crystalline layered titanic acid containing water and at least one selected from the group consisting of potassium carbonate and potassium bicarbonate in the crystal structure. It was presumed to be potassium and had excellent strontium adsorption ability.
  • Example 2 10.4 g of anhydrous potassium carbonate powder (150 mmol as K), 13 g of potassium sulfate powder and 9.8 g of metatitanic acid powder (100 mmol as Ti) are well mixed in a mortar, put in an alumina crucible and heated at 900 ° C. for 20 hours. did. The product was coarsely crushed in a mortar, suspended in 350 g of deionized water and stirred for 1 hour. Next, the mixture was filtered under reduced pressure to form a dehydrated cake, and rinsed with 100 g of deionized water while continuing filtration under reduced pressure. The washed cake was dried with hot air at 50 ° C. to obtain a white powder.
  • the obtained white powder was subjected to metal element composition analysis, C and H content measurement, powder X-ray diffraction, TG-MS analysis, 13 C-NMR and strontium adsorption test.
  • Table 1 shows the results. From the results shown in Table 1, the obtained white powder was a low-crystalline layered potassium titanate containing water and at least one selected from the group consisting of potassium carbonate and potassium bicarbonate in the crystal structure. It was presumed that the compound had excellent strontium adsorption ability.
  • Example 3 21.2 g of anhydrous sodium carbonate powder was dissolved in 200 ml of water, and 240 g (100 mmol as Ti) of a 10% by weight aqueous solution of titanium sulfate was added dropwise over 30 minutes while stirring at room temperature. The produced titanium hydroxide was recovered by centrifugation, evaporated to dryness at 100 ° C., and ground in a mortar to obtain 11.3 g of titanium hydroxide powder. The total amount of the titanium hydroxide powder, 15.9 g of anhydrous sodium carbonate powder (300 mmol as Na), and 25 g of potassium sulfate powder were mixed well in a mortar, and placed in an alumina crucible and heated at 900 ° C. for 20 hours.
  • the product was coarsely crushed in a mortar, suspended in 500 g of deionized water and stirred for 1 hour. Next, the mixture was filtered under reduced pressure to form a dehydrated cake, and rinsed with 100 g of deionized water while continuing filtration under reduced pressure. The washed cake was dried with hot air at 50 ° C. to obtain a white powder. The obtained white powder was subjected to metal element composition analysis, C and H content measurement, powder X-ray diffraction, TG-MS analysis, 13 C-NMR and strontium adsorption test. Table 1 shows the results.
  • the obtained white powder is a low-crystalline layered sodium titanate containing water and at least one selected from the group consisting of sodium carbonate and sodium bicarbonate in the crystal structure. It was presumed that the compound had excellent strontium adsorption ability.
  • Example 4 14.9 g of anhydrous lithium carbonate powder was dissolved in 200 ml of water, heated to 70 ° C., and 190 g (100 mmol as Ti) of a 10% by weight aqueous solution of titanium tetrachloride was added dropwise with stirring over 30 minutes. The generated titanium hydroxide was collected by centrifugation, evaporated to dryness at 100 ° C., and ground in a mortar to obtain 12.8 g of titanium hydroxide powder.
  • the total amount of the titanium hydroxide powder, 9.2 g (250 mmol as Li) of anhydrous lithium carbonate powder and 25 g of potassium sulfate powder were mixed well in a mortar, and placed in an alumina crucible and heated at 900 ° C. for 20 hours.
  • the product was coarsely crushed in a mortar, suspended in 500 g of deionized water and stirred for 1 hour.
  • the mixture was filtered under reduced pressure to form a dehydrated cake, and rinsed with 100 g of deionized water while continuing the reduced pressure filtration.
  • the washed cake was dried with hot air at 50 ° C. to obtain a white powder.
  • the obtained white powder was subjected to metal element composition analysis, C and H content measurement, powder X-ray diffraction, TG-MS analysis, 13 C-NMR and strontium adsorption test.
  • Table 1 shows the results. From the results shown in Table 1, the obtained white powder is a low-crystalline layered structure lithium titanate containing water and at least one selected from the group consisting of lithium carbonate and lithium hydrogen carbonate in the crystal structure. And had excellent strontium adsorption ability.
  • Comparative Example 2 1 g of the potassium titanate obtained in Comparative Example 1 was suspended in 60 g of deionized water and stirred for 48 hours. Then, the mixture was filtered under reduced pressure to form a dehydrated cake, and rinsed with 10 g of deionized water while continuing the reduced pressure filtration. The washed cake was air-dried at room temperature to obtain a white powder. The obtained white powder was subjected to metal element composition analysis, C and H content measurement, powder X-ray diffraction, TG-MS analysis, 13 C-NMR and strontium adsorption test. Table 1 shows the results.
  • the product was coarsely crushed in a mortar, suspended in 500 g of deionized water and stirred for 1 hour. Next, the mixture was filtered under reduced pressure to form a dehydrated cake, and rinsed with 100 g of deionized water while continuing filtration under reduced pressure. The washed cake was dried with hot air at 50 ° C. to obtain a white powder.
  • the obtained white powder was subjected to metal element composition analysis, C and H content measurement, powder X-ray diffraction, TG-MS analysis, 13 C-NMR and strontium adsorption test. Table 1 shows the results. From the results shown in Table 1, it was estimated that the obtained white powder was sodium titanate having a tunnel structure and containing no alkali metal carbonate or alkali metal carbonate in the crystal structure.
  • the total amount of the titanium hydroxide powder, 7.4 g of anhydrous lithium carbonate powder (200 mmol as Li), and 25 g of potassium sulfate powder were mixed well in a mortar, and placed in an alumina crucible and heated at 900 ° C. for 20 hours.
  • the product was coarsely crushed in a mortar, suspended in 500 g of deionized water and stirred for 1 hour.
  • the mixture was filtered under reduced pressure to form a dehydrated cake, and rinsed with 100 g of deionized water while continuing filtration under reduced pressure.
  • the washed cake was dried with hot air at 50 ° C. to obtain a white powder.
  • the obtained white powder was subjected to metal element composition analysis, C and H content measurement, powder X-ray diffraction, TG-MS analysis, 13 C-NMR and strontium adsorption test. Table 1 shows the results. From the results shown in Table 1, it was estimated that the obtained white powder was layered lithium titanate containing no alkali metal carbonate and no alkali metal carbonate in the crystal structure.
  • the layered titanates of Examples 1 to 4 each had a diffraction peak having a maximum point in the range of a diffraction angle (2 ⁇ ) of 1 ° or more and 8 ° or less, It was confirmed that the interlayer distance of titanic acid was large.
  • the titanates of Comparative Examples 1 to 4 have a diffraction angle (2 ⁇ ) of more than 8 °, and the interlayer distance of titanic acid is smaller than that of the layered titanates of Examples 1 to 4. Had become.
  • the layered titanates of Examples 1 to 4 had a half width of the diffraction peak of powder X-ray diffraction of 2 ⁇ , which was 3 ° or more, and were confirmed to be low crystalline titanates. .
  • the titanates of Comparative Examples 1 to 4 had a half width at half maximum of the diffraction peak of powder X-ray diffraction of 2 ⁇ , which was 1 ° or less, and were confirmed to be titanates with high crystallinity.
  • TG-MS it was confirmed that the layered titanates of Examples 1 to 4 contained water in the crystal structure.
  • the titanates of Comparative Examples 1, 2 and 4 did not contain water in the crystal structure.
  • the inorganic ion exchanger of the present invention has a high ion exchange capacity and can remove radioactive substances from water containing radioactive substances with high efficiency. For this reason, for example, removal of heavy metals from various waters such as well water, lake water, river water, rainwater, spring water, sewage water, factory water supply, medium water, sewage, etc., recovery of valuable resources from seawater, pollution It can also be used to remove harmful substances from soil.

Abstract

The present invention provides: an inorganic ion exchanger which has high ion exchange capacity and is capable of removing a radioactive substance from a radioactive waste liquid with high efficiency; and a method for purifying water containing a radioactive substance, which uses this inorganic ion exchanger. The present invention provides: an inorganic ion exchanger which contains a layered titanate that contains, in the crystal structure, at least one substance selected from the group consisting of alkali metal carbonates and alkali metal hydrogen carbonates; a method for producing this inorganic ion exchanger; and a method for purifying water containing radioactive strontium, which uses this inorganic ion exchanger.

Description

無機イオン交換体及びその製造方法、並びに放射性ストロンチウムを含有する水の浄化方法Inorganic ion exchanger, method for producing the same, and method for purifying water containing radioactive strontium
　本発明は、無機イオン交換体及びその製造方法に関する。また、本発明は、該無機イオン交換体を用いる、放射性ストロンチウムを含有する水の浄化方法に関する。 The present invention relates to an inorganic ion exchanger and a method for producing the same. The present invention also relates to a method for purifying water containing radioactive strontium, using the inorganic ion exchanger.
　原子力発電設備の事故等で排出された放射性廃液中の放射性物質の除去や有価元素の回収のために、合成ゼオライト系吸着剤や陽イオン交換樹脂を用いる方法の他、チタン酸アルカリ金属化合物をイオン交換体として用いる方法が提案されている。
　イオン交換体として用いるチタン酸アルカリ金属化合物としては、ＴｉＯ５三角両錐体の連鎖構造を有する層状構造チタン酸アルカリ金属化合物と、ＴｉＯ６八面体の連鎖構造を有する層状チタン酸アルカリ金属塩とからなる多孔質チタネート（特許文献１）、ケイ酸源と、ナトリウム及び／又はカリウム化合物と、四塩化チタンと、水とを混合して混合ゲルを得、該混合ゲルを水熱反応させて得られる結晶性シリコチタネート（特許文献２）等が知られている。チタン酸アルカリ金属化合物として、四チタン酸カリウムＫ２Ｔｉ４Ｏ９は、結晶の層間に水を取り込むことにより、カリウムイオンをカルシウムイオンと交換できることが知られている（非特許文献１）。 In order to remove radioactive substances and recover valuable elements in radioactive waste liquid discharged in the event of a nuclear power plant accident, etc., in addition to methods using synthetic zeolite-based adsorbents and cation exchange resins, alkali metal titanate compounds are ionized. Methods have been proposed for use as exchangers.
Examples of the alkali metal titanate compound used as the ion exchanger include a layered structure alkali metal titanate having a TiO 5 triangular bipyramidal chain structure and a layered alkali metal titanate having a TiO 6 octahedral chain structure. (Patent Document 1), a silicic acid source, a sodium and / or potassium compound, titanium tetrachloride, and water are mixed to obtain a mixed gel, and the mixed gel is obtained by a hydrothermal reaction. Crystalline silico titanates (Patent Document 2) and the like are known. As an alkali metal titanate compound, potassium tetratitanate K 2 Ti 4 O 9 is known to be able to exchange potassium ions for calcium ions by taking in water between crystal layers (Non-Patent Document 1).
特開２０１５－１８８７９８号公報JP 2015-188798 A 特開２０１５－１８８７８２号公報JP-A-2015-188782
　しかしながら、従来の合成ゼオライト系吸着剤や陽イオン交換樹脂を用いる方法や、従来のチタン酸アルカリ金属化合物をイオン交換体として用いる方法では、放射性ストロンチウム除去能が十分ではないという課題があった。
　本発明が解決しようとする課題は、放射性ストロンチウムが基準値以下になるまで放射性ストロンチウムを除去することができる無機イオン交換体、及び該無機イオン交換体の製造方法、並びに該無機イオン交換体を用いる、放射性ストロンチウムを含有する水の浄化方法を提供することにある。 However, the conventional method using a synthetic zeolite-based adsorbent or a cation exchange resin or the conventional method using an alkali metal titanate compound as an ion exchanger has a problem that the ability to remove radioactive strontium is not sufficient.
The problem to be solved by the present invention is to use an inorganic ion exchanger capable of removing radioactive strontium until the radioactive strontium falls below a reference value, a method for producing the inorganic ion exchanger, and using the inorganic ion exchanger. Another object of the present invention is to provide a method for purifying water containing radioactive strontium.
　本発明者は、結晶構造内に、アルカリ金属塩およびアルカリ金属炭酸塩からなる群から選ばれる少なくとも１種を含有する層状チタン酸塩を含む無機イオン交換体が、高いイオン交換能を有し、放射性ストロンチウムを含有する水から高い効率で放射性ストロンチウムを除去できることを見出し、本発明を完成するに至った。 The present inventor has found that an inorganic ion exchanger containing a layered titanate containing at least one selected from the group consisting of an alkali metal salt and an alkali metal carbonate in a crystal structure has high ion exchange ability, The present inventors have found that radioactive strontium can be removed from water containing radioactive strontium with high efficiency, and have completed the present invention.
　即ち、本発明は、以下の［１］～［１０］に関する。
［１］結晶構造内に、アルカリ金属炭酸塩およびアルカリ金属炭酸水素塩からなる群から選ばれる少なくとも１種を含有する層状チタン酸塩を含む無機イオン交換体。
［２］前記層状チタン酸塩が、ｘＡ２Ｏ・ＴｉＯ２・ｙＨ２Ｏ・ｚＡ２ＣＯ３（ＡはＬｉ、Ｋ、Ｎａ、Ｒｂ及びＣｓから選ばれる少なくとも１種の元素を表し、ｘ、ｙ、ｚは、それぞれ０．０２≦ｘ≦２．０、ｙ≧０．０５、ｚ≧０．０１５の数値を表す）で表されることを特徴とする［１］に記載の無機イオン交換体。
［３］前記層状チタン酸塩が、ＣｕＫα線を用いて測定した粉末Ｘ線回折パターンにおいて、回折角（２θ）が１°以上８°以下の範囲に極大点のある回折ピークを有することを特徴とする［１］または［２］に記載の無機イオン交換体。
［４］前記層状チタン酸塩が、前記回折ピークの半値幅が２θで３°以上である低結晶性の化合物であることを特徴とする［３］に記載の無機イオン交換体。
［５］ｐＨが１２以上のアルカリ性ストロンチウム水溶液に分散させたときに、下記式（１）で表される分配係数Ｋｄが３００００ｍｌ／ｇ以上であることを特徴とする［１］～［４］のいずれか一項に記載の無機イオン交換体。 That is, the present invention relates to the following [1] to [10].
[1] An inorganic ion exchanger containing a layered titanate containing at least one selected from the group consisting of alkali metal carbonates and alkali metal bicarbonates in the crystal structure.
[2] The layered titanate is, xA 2 O · TiO 2 · yH 2 O · zA 2 CO 3 (A represents Li, K, Na, at least one element selected from Rb and Cs, x, y and z are respectively represented by 0.02 ≦ x ≦ 2.0, y ≧ 0.05 and z ≧ 0.015). The inorganic ion exchange according to [1], wherein body.
[3] The layered titanate has a diffraction peak having a maximum point in a range of a diffraction angle (2θ) of 1 ° or more and 8 ° or less in a powder X-ray diffraction pattern measured using CuKα radiation. [1] or the inorganic ion exchanger according to [2].
[4] The inorganic ion exchanger according to [3], wherein the layered titanate is a low-crystalline compound having a half width of the diffraction peak of 3 ° or more at 2θ.
[5] The method according to any of [1] to [4], wherein when dispersed in an aqueous alkaline strontium solution having a pH of 12 or more, the distribution coefficient Kd represented by the following formula (1) is 30000 ml / g or more. An inorganic ion exchanger according to any one of the preceding claims.
　Ｋｄ＝Ｑｅｑ／Ｃｅｑ・・・（１）
　（式（１）中、Ｋｄは分配係数（ｍｌ／ｇ）、Ｃｅｑは平衡到達時の水溶液中のストロンチウム濃度（ｍｏｌ／ｍｌ）、Ｑｅｑは平衡到達時の無機イオン交換体の単位重量当たりのストロンチウム吸着量（ｍｏｌ／ｇ）をそれぞれ表す）
［６］［１］～［５］のいずれか一項に記載の無機イオン交換体の製造方法であって、以下の工程（１）及び工程（２）を順次行うことを特徴とする無機イオン交換体の製造方法。
　工程（１）：チタン化合物の粉末と過剰量の、アルカリ金属炭酸塩およびアルカリ金属炭酸水素塩からなる群から選ばれる少なくとも1種の粉末とを混合する工程
　工程（２）：前記工程（１）で得られた混合物を７００℃以上１５００℃以下で加熱する工程
［７］さらに以下の工程（３）及び工程（４）を順次行うことを特徴とする［６］に記載の無機イオン交換体の製造方法。
　工程（３）：前記工程（２）で得られた無機イオン交換体を水で洗浄する工程
　工程（４）：前記工程（３）で洗浄後の無機イオン交換体を乾燥する工程
［８］前記チタン化合物が、酸化チタン、メタチタン酸、アルカリ金属チタン酸塩、および金属チタンからなる群から選ばれる少なくとも１種であることを特徴とする［６］又は［７］に記載の無機イオン交換体の製造方法。
［９］前記工程（１）において、アルカリ金属硫酸塩の粉末をさらに混合することを特徴とする［６］～［８］のいずれか一項に記載の無機イオン交換体の製造方法。
［１０］［１］～［５］のいずれか一項に記載の無機イオン交換体に、放射性ストロンチウムを含有する水を接触させる工程と、前記接触後の水から前記無機イオン交換体を分離する工程とを順次行うことを特徴とする、放射性ストロンチウムを含有する水の浄化方法。 Kd = Qeq / Ceq (1)
(In the formula (1), Kd is the partition coefficient (ml / g), Ceq is the strontium concentration in the aqueous solution when the equilibrium is reached (mol / ml), and Qeq is strontium per unit weight of the inorganic ion exchanger when the equilibrium is reached. (Denotes the adsorption amount (mol / g), respectively)
[6] The method for producing an inorganic ion exchanger according to any one of [1] to [5], wherein the following steps (1) and (2) are sequentially performed. How to make exchangers.
Step (1): mixing the titanium compound powder with an excess amount of at least one powder selected from the group consisting of alkali metal carbonates and alkali metal bicarbonates Step (2): the step (1) [7] a step of heating the mixture obtained in the above at a temperature of 700 ° C. or more and 1500 ° C. or less, wherein the following steps (3) and (4) are sequentially performed. Production method.
Step (3): a step of washing the inorganic ion exchanger obtained in the step (2) with water Step (4): a step of drying the inorganic ion exchanger after the washing in the step (3) [8] The inorganic ion exchanger according to [6] or [7], wherein the titanium compound is at least one selected from the group consisting of titanium oxide, metatitanic acid, alkali metal titanate, and metal titanium. Production method.
[9] The method for producing an inorganic ion exchanger according to any one of [6] to [8], wherein in the step (1), a powder of an alkali metal sulfate is further mixed.
[10] A step of contacting the inorganic ion exchanger according to any one of [1] to [5] with water containing radioactive strontium, and separating the inorganic ion exchanger from the water after the contact. A method for purifying water containing radioactive strontium, wherein the steps are sequentially performed.
　本発明の無機イオン交換体は、高いイオン交換能を有し、放射性物質を含有する水から高い効率で放射性物質を除去することができる。このため、放射性廃液から放射性物質を除去する際に、無機イオン交換体としての使用量を削減でき、浄化コストの削減及び放射性廃棄物の量を低減することができる。また、本発明の無機イオン交換体は、井戸水などからの重金属除去、海水などからの有価資源回収、汚染土上からの有害物質除去などにも使用することができる。 The inorganic ion exchanger of the present invention has a high ion exchange capacity and can remove radioactive substances from water containing radioactive substances with high efficiency. For this reason, when removing a radioactive substance from a radioactive waste liquid, the amount used as an inorganic ion exchanger can be reduced, the purification cost can be reduced, and the amount of radioactive waste can be reduced. Further, the inorganic ion exchanger of the present invention can be used for removing heavy metals from well water, recovering valuable resources from seawater, and removing harmful substances from contaminated soil.
実施例１で得られた層状チタン酸塩の粉末Ｘ線回折パターンである。3 is a powder X-ray diffraction pattern of the layered titanate obtained in Example 1. 実施例１で得られた層状チタン酸塩の１３Ｃ－ＮＭＲスペクトルである。3 is a 13 C-NMR spectrum of the layered titanate obtained in Example 1.
＜無機イオン交換体＞
　本発明の無機イオン交換体は、結晶構造内に、アルカリ金属炭酸塩およびアルカリ金属炭酸水素塩からなる群から選ばれる少なくとも１種を含有する層状チタン酸塩を含む。
　前記層状チタン酸塩の結晶構造内に含有されるアルカリ金属炭酸塩としては、例えば、炭酸リチウム、炭酸ナトリウム、炭酸カリウム、炭酸ルビジウム、炭酸セシウム等が挙げられ、これらは、単独で含有されていてもよいし、２種以上が組み合わされて含有されていてもよい。
　また、前記層状チタン酸塩の結晶構造内に含有されるアルカリ金属炭酸水素塩としては、例えば、炭酸水素リチウム、炭酸水素ナトリウム、炭酸水素カリウム、炭酸水素ルビジウム、炭酸水素セシウム等が挙げられ、これらは、単独で含有されていてもよいし、２種以上が組み合わされて含有されていてもよい。 <Inorganic ion exchanger>
The inorganic ion exchanger of the present invention contains, in its crystal structure, a layered titanate containing at least one selected from the group consisting of alkali metal carbonates and alkali metal bicarbonates.
Examples of the alkali metal carbonate contained in the crystal structure of the layered titanate include, for example, lithium carbonate, sodium carbonate, potassium carbonate, rubidium carbonate, cesium carbonate, and the like. Or two or more of them may be contained in combination.
Examples of the alkali metal bicarbonate contained in the crystal structure of the layered titanate include, for example, lithium bicarbonate, sodium bicarbonate, potassium bicarbonate, rubidium bicarbonate, cesium bicarbonate, and the like. May be contained alone or in combination of two or more.
　本発明の無機イオン交換体の形態としては、特に制限はなく、粉末状、顆粒状、粒子状、円柱状、球状、ペレット状、ハニカム成型体、多孔質成型体等を挙げることができ、さらに、アルミナ、ジルコニア、コージェライトなどの支持体の上に担持されたものでもよい。イオン交換体は、一般的には、カラムに充填して放射性廃液などを通液する方法で用いられるため、１ｍｍ程度の大きさの顆粒状または粒子状で、水と長時間接触しても脆化しない形態であることが好ましい。
　本発明の無機イオン交換体における前記層状チタン酸塩としては、ｘＡ２Ｏ・ＴｉＯ２・ｙＨ２Ｏ・ｚＡ２ＣＯ３（ＡはＬｉ、Ｋ、Ｎａ、Ｒｂ及びＣｓから選ばれる少なくとも１種の元素を表し、ｘ、ｙ、ｚは、それぞれ０．０２≦ｘ≦２．０、ｙ≧０．０５、ｚ≧０．０１５の数値を表す）で表される層状チタン酸塩であることが好ましい。ここで、ｘは、０．０５≦ｘ≦１．０であることが好ましく、０．１≦ｘ≦０．５であることがより好ましい。ｙは、０．０５≦ｙ≦３．０であることが好ましく、０．１≦ｙ≦２．０であることがより好ましい。ｚは、０．０１５≦ｚ≦１．５であることが好ましく、０．０２≦ｚ≦１．０であることがより好ましい。 The form of the inorganic ion exchanger of the present invention is not particularly limited, and examples thereof include powder, granules, particles, columns, spheres, pellets, honeycomb molded bodies, and porous molded bodies. , Alumina, zirconia, cordierite or the like may be supported on a support. Since the ion exchanger is generally used in a method of packing a column and passing a radioactive waste liquid or the like, the ion exchanger is in the form of granules or particles having a size of about 1 mm and is fragile even if it is in contact with water for a long time. It is preferable that the form is not changed.
As the layered titanate in the inorganic ion exchanger of the present invention, xA 2 O · TiO 2 · yH 2 O · zA 2 CO 3 (A is Li, K, Na, at least one selected from Rb and Cs X, y, and z each represent a numerical value of 0.02 ≦ x ≦ 2.0, y ≧ 0.05, and z ≧ 0.015). preferable. Here, x is preferably 0.05 ≦ x ≦ 1.0, and more preferably 0.1 ≦ x ≦ 0.5. y is preferably 0.05 ≦ y ≦ 3.0, and more preferably 0.1 ≦ y ≦ 2.0. z is preferably 0.015 ≦ z ≦ 1.5, and more preferably 0.02 ≦ z ≦ 1.0.
　なお、前記ｚＡ２ＣＯ３は、ｚＡＨＣＯ３であってもよく、この場合の水素イオンは、ｙＨ２Ｏから得られる。従って、前記ｚＡ２ＣＯ３がｚＡＨＣＯ３である場合は、前記層状チタン酸塩は、ｘＡ２Ｏ・ＴｉＯ２・（ｙ－ｚ）Ｈ２Ｏ・ｚＡＨＣＯ３・ｚＡＯＨ（ＡはＬｉ、Ｋ、Ｎａ、Ｒｂ及びＣｓから選ばれる少なくとも１種の元素を表し、ｘ、ｙ、ｚは、それぞれ０．０２≦ｘ≦２．０、ｙ≧０．０５、ｚ≧０．０１５の数値を表す）となる。 The zA 2 CO 3 may be zAHCO 3 , and the hydrogen ion in this case is obtained from yH 2 O. Therefore, if the said zA 2 CO 3 is ZAHCO 3, the layered titanate, xA 2 O · TiO 2 · (y-z) H 2 O · zAHCO 3 · zAOH (A is Li, K, Na , Rb and Cs represent at least one element selected from the group consisting of x, y and z, each of which represents a value of 0.02 ≦ x ≦ 2.0, y ≧ 0.05 and z ≧ 0.015); Become.
　前記層状チタン酸塩は、ＣｕＫα線を用いて測定した粉末Ｘ線回折パターンにおいて、回折角（２θ）が１°以上８°以下、好ましくは２°以上７°以下の範囲に極大点のある回折ピークを有することが好ましい。前記粉末Ｘ線回折パターンにおいて、回折角（２θ）が１°以上８°以下、好ましくは２°以上７°以下の範囲に極大点のある回折ピークを有する層状チタン酸塩は、チタン酸の層間距離が、１．１ｎｍ～８．８ｎｍ、好ましくは、１．３ｎｍ～４．４ｎｍとなる。前記回折ピークの回折角（２θ）は、実際の粉末Ｘ線回折で得られた回折ピークパターンをベースライン補正した、回折パターンより算出することができる。このベースライン補正は、算出対象の回折角度範囲に回折ピークを有さない化合物で得られたバックグランド曲線をフィッテングさせることにより行うことができる。 The layered titanate has a diffraction point (2θ) having a maximum point in a range of 1 ° or more and 8 ° or less, preferably 2 ° or more and 7 ° or less in a powder X-ray diffraction pattern measured using CuKα radiation. It preferably has a peak. In the powder X-ray diffraction pattern, a layered titanate having a diffraction peak having a maximum point in the range of a diffraction angle (2θ) of 1 ° or more and 8 ° or less, preferably 2 ° or more and 7 ° or less, is formed by an interlayer of titanic acid. The distance is 1.1 nm to 8.8 nm, preferably 1.3 nm to 4.4 nm. The diffraction angle (2θ) of the diffraction peak can be calculated from a diffraction pattern obtained by correcting a diffraction peak pattern obtained by actual powder X-ray diffraction with a baseline. This baseline correction can be performed by fitting a background curve obtained from a compound having no diffraction peak in the diffraction angle range to be calculated.
　また、前記層状チタン酸塩は、前記回折ピークの半値幅が２θで３°以上である低結晶性であることが好ましい。前記回折ピークの半値幅が広くなる程、結晶性が低くなり、前記回折ピークの半値幅が狭くなる程、結晶性が高くなる。本発明における層状チタン酸塩は、前記回折ピークの半値幅が２θで３°以上である低結晶性の化合物であることが好ましく、３°以上１０°以下である低結晶性の化合物がより好ましい。 Further, it is preferable that the layered titanate has low crystallinity in which the half value width of the diffraction peak is 3 ° or more at 2θ. As the half width of the diffraction peak increases, the crystallinity decreases, and as the half width of the diffraction peak decreases, the crystallinity increases. The layered titanate in the present invention is preferably a low crystalline compound having a half value width of the diffraction peak of 3 ° or more at 2θ, more preferably a low crystalline compound of 3 ° or more and 10 ° or less. .
　前記回折ピークの半値幅は、実際の粉末Ｘ線回折で得られた回折ピークパターンをベースライン補正した、回折パターンより算出することができる。このベースライン補正は、算出対象の回折角度範囲に回折ピークを有さない化合物で得られたバックグランド曲線をフィッテングさせることにより行うことができる。また、前記回折ピークパターンが、他の回折ピークと重なり合っている場合は、ピーク分離を行った後に半値幅を求めることができる。ピーク分離は、ガウス型の基本波形の重ね合わせにより近似し、重なりあったピークのそれぞれをカーブフィッテングすることにより行うことができる。 半 The half width of the diffraction peak can be calculated from the diffraction pattern obtained by correcting the diffraction peak pattern obtained by actual powder X-ray diffraction with a baseline. This baseline correction can be performed by fitting a background curve obtained from a compound having no diffraction peak in the diffraction angle range to be calculated. When the diffraction peak pattern overlaps with other diffraction peaks, the half width can be obtained after peak separation. Peak separation can be performed by approximating Gaussian basic waveforms by superimposition and performing curve fitting on each of the overlapping peaks.
　本発明の無機イオン交換体は、上記の通り、層状チタン酸塩の結晶構造内に、アルカリ金属炭酸塩およびアルカリ金属炭酸水素塩からなる群から選ばれる少なくとも１種を含んでおり、このアルカリ金属炭酸塩またはアルカリ金属炭酸水素塩の介在により、チタン酸の層間距離が広がった構造を有している。従来の層状チタン酸塩を含む無機イオン交換体は、チタン酸の層間に水分子を含んだ構造を有し、チタン酸の層間距離が広がっているが、本発明の無機イオン交換体は、チタン酸の層間に、アルカリ金属炭酸塩およびアルカリ金属炭酸水素塩からなる群から選ばれる少なくとも１種を含むことにより、従来の水分子をチタン酸の層間に含む無機イオン交換体よりも、さらに多くの水分子を含み得るため、チタン酸の層間距離がさらに広がった構造を形成し得るためと推定される。 As described above, the inorganic ion exchanger of the present invention contains at least one selected from the group consisting of alkali metal carbonates and alkali metal bicarbonates in the crystal structure of the layered titanate. It has a structure in which the interlayer distance between titanic acids is widened by the intervening carbonate or alkali metal bicarbonate. A conventional inorganic ion exchanger containing a layered titanate has a structure containing water molecules between layers of titanic acid, and the interlayer distance between titanic acids is widened. By containing at least one selected from the group consisting of alkali metal carbonates and alkali metal bicarbonates between the acid layers, an even larger number of inorganic ion exchangers than conventional inorganic ion exchangers containing water molecules between titanic acid layers can be obtained. It is presumed that a structure in which the interlayer distance of the titanic acid is further increased can be formed because water molecules can be contained.
　また、本発明の無機イオン交換体は、さらに水分子を結晶構造内に取り込むことができる。すなわち、本発明の無機イオン交換体は、層状チタン酸塩の結晶構造内に、アルカリ金属炭酸塩およびアルカリ金属炭酸水素塩からなる群から選ばれる少なくとも１種と水分子とを含有するものも包含する。水分子と、アルカリ金属炭酸塩およびアルカリ金属炭酸水素塩からなる群から選ばれる少なくとも１種とを両方含む場合は、水分子のみ、または、アルカリ金属炭酸塩およびアルカリ金属炭酸水素塩からなる群から選ばれる少なくとも１種のみを含む場合に比べて、本発明の技術的効果が相乗的に発現することが期待できる。 無機 In addition, the inorganic ion exchanger of the present invention can further incorporate water molecules into the crystal structure. That is, the inorganic ion exchanger of the present invention includes those containing water molecules and at least one selected from the group consisting of alkali metal carbonates and alkali metal bicarbonates in the crystal structure of the layered titanate. I do. When containing both water molecules and at least one selected from the group consisting of alkali metal carbonates and alkali metal bicarbonates, only water molecules or from the group consisting of alkali metal carbonates and alkali metal bicarbonates It can be expected that the technical effects of the present invention will be exhibited synergistically as compared with the case where only at least one selected type is included.
＜無機イオン交換体の分配係数＞
　本発明の無機イオン交換体を、ストロンチウムを含む水溶液に分散させると、無機イオン交換体中のアルカリ金属が、水溶液中のストロンチウムと交換反応し、ストロンチウムが無機イオン交換体に取り込まれ、ストロンチウムが取り込まれた無機イオン交換体が生成し得る。この反応は下記式に示す平衡反応であり、平衡がストロンチウムの取り込みの側（右側）へ傾く程、ストロンチウムの取り込み量が高くなり得る。 <Partition coefficient of inorganic ion exchanger>
When the inorganic ion exchanger of the present invention is dispersed in an aqueous solution containing strontium, the alkali metal in the inorganic ion exchanger undergoes an exchange reaction with strontium in the aqueous solution, strontium is incorporated into the inorganic ion exchanger, and strontium is incorporated. Inorganic ion exchangers can be formed. This reaction is an equilibrium reaction represented by the following formula. The more the equilibrium is inclined toward the side of strontium incorporation (to the right), the higher the amount of strontium incorporation can be.
Figure JPOXMLDOC01-appb-C000001
 （式中、Ａはアルカリ金属、ＩＥＸは無機イオン交換体をそれぞれ表す）
Figure JPOXMLDOC01-appb-C000001
 (In the formula, A represents an alkali metal, and IEX represents an inorganic ion exchanger.)
　無機イオン交換体のストロンチウム取り込み能は、該無機イオン交換体をｐＨが１２以上のアルカリ性ストロンチウム水溶液に分散させたときの、下記式（１）で表される分配係数Ｋｄで表すことができる。
　Ｋｄ＝Ｑｅｑ／Ｃｅｑ・・・（１）
　（式（１）中、Ｋｄは分配係数（ｍｌ／ｇ）、Ｃｅｑは上記平衡反応における平衡到達時の溶液中のストロンチウム濃度（ｍｏｌ／ｍｌ）、Ｑｅｑは上記平衡反応における平衡到達時の無機イオン交換体の単位重量当たりのストロンチウム吸着量（ｍｏｌ／ｇ）をそれぞれ表す）
　上記平衡反応において、平衡到達時は、本発明の無機イオン交換体を、ストロンチウムを含む水溶液に分散させた後、水溶液中のストロンチウム濃度を測定して、濃度の変化がなくなる時間を求めることにより確認することができるが、通常は、３～５時間である。 The strontium uptake capacity of the inorganic ion exchanger can be represented by a partition coefficient Kd represented by the following formula (1) when the inorganic ion exchanger is dispersed in an aqueous alkaline strontium solution having a pH of 12 or more.
Kd = Qeq / Ceq (1)
(In the formula (1), Kd is the partition coefficient (ml / g), Ceq is the strontium concentration (mol / ml) in the solution when the equilibrium reaction is reached, and Qeq is the inorganic ion when the equilibrium is reached in the equilibrium reaction. (Represents the strontium adsorption amount (mol / g) per unit weight of the exchanger)
In the equilibrium reaction, when the equilibrium is reached, the inorganic ion exchanger of the present invention is dispersed in an aqueous solution containing strontium, and then the strontium concentration in the aqueous solution is measured, and the time is determined by determining the time at which the change in the concentration stops. But usually for 3-5 hours.
　本発明の無機イオン交換体の分配係数Ｋｄは、３００００ｍｌ／ｇ以上であることが好ましく、１０００００ｍｌ／ｇ以上であることがより好ましく、５０００００ｍｌ／ｇ以上であることが更に好ましい。
　上記の平衡反応において、分配係数Ｋｄが高い程、平衡はストロンチウムの取り込みの側（右側）へ傾き、ストロンチウムの取り込み能が高くなる。上記の通り、本発明の無機イオン交換体の分配係数Ｋｄは高いため、高いストロンチウム取り込み能を有している。
　なお、本明細書においては、イオン交換体が、イオン交換によりストロンチウムを取り込む現象を、ストロンチウム吸着と呼ぶ。 The partition coefficient Kd of the inorganic ion exchanger of the present invention is preferably at least 30,000 ml / g, more preferably at least 100,000 ml / g, even more preferably at least 500,000 ml / g.
In the above equilibrium reaction, the higher the partition coefficient Kd, the more the equilibrium is inclined toward the strontium incorporation side (right side), and the higher the strontium incorporation ability. As described above, since the partition coefficient Kd of the inorganic ion exchanger of the present invention is high, it has a high strontium uptake ability.
In this specification, a phenomenon in which an ion exchanger takes in strontium by ion exchange is referred to as strontium adsorption.
＜無機イオン交換体の製造方法＞
　本発明の無機イオン交換体は、以下の工程（１）及び工程（２）を順次行うことにより製造することができる。
　工程（１）：チタン化合物の粉末と過剰量の、アルカリ金属炭酸塩およびアルカリ金属炭酸水素塩からなる群から選ばれる少なくとも１種の粉末とを混合する工程
　工程（２）：前記工程（１）で得られた混合物を７００℃以上１５００℃以下で加熱する工程 <Production method of inorganic ion exchanger>
The inorganic ion exchanger of the present invention can be produced by sequentially performing the following steps (1) and (2).
Step (1): mixing a titanium compound powder with an excess amount of at least one powder selected from the group consisting of alkali metal carbonates and alkali metal bicarbonates Step (2): the step (1) Heating the mixture obtained in the above at a temperature of 700 ° C. or more and 1500 ° C. or less
　工程（１）は、チタン化合物の粉末と過剰量の、アルカリ金属炭酸塩およびアルカリ金属炭酸水素塩からなる群から選ばれる少なくとも１種（以下、アルカリ金属炭酸塩等ともいう）の粉末とを混合する工程である。チタン化合物の粉末と混合するアルカリ金属炭酸塩等の粉末量は、チタン化合物の粉末量よりも過剰であれば、特に制限はないが、チタン化合物をチタン元素換算１００ｍｏｌ％に対して、１２０ｍｏｌ％以上であることが好ましく、１５０ｍｏｌ％以上であることがより好ましく、２００ｍｏｌ％以上であることがさらに好ましい。 In the step (1), a titanium compound powder and an excess amount of at least one kind of powder (hereinafter, also referred to as an alkali metal carbonate or the like) selected from the group consisting of alkali metal carbonates and alkali metal bicarbonates are mixed. This is the step of performing The amount of the powder of the alkali metal carbonate or the like mixed with the powder of the titanium compound is not particularly limited as long as it is more than the amount of the powder of the titanium compound. Is preferably, more preferably, 150 mol% or more, and further preferably, 200 mol% or more.
　本発明の無機イオン交換体の製造方法に用いられる、アルカリ金属炭酸塩およびアルカリ金属炭酸水素塩としては、前述のアルカリ金属炭酸塩およびアルカリ金属炭酸水素塩が挙げられる。本発明の無機イオン交換体の製造方法に用いられる前記チタン化合物としては、酸化チタン、メタチタン酸、アルカリ金属チタン酸塩、金属チタン等が挙げられ、これらは、単独で用いてもよいし、２種以上を組み合わせて用いてもよい。アルカリ金属チタン酸塩としては、チタン酸リチウム、チタン酸ナトリウム、チタン酸カリウム、チタン酸ルビジウム、チタン酸セシウム等が挙げられる。 ア ル カ リ The alkali metal carbonate and alkali metal bicarbonate used in the method for producing an inorganic ion exchanger of the present invention include the above-mentioned alkali metal carbonate and alkali metal bicarbonate. Examples of the titanium compound used in the method for producing an inorganic ion exchanger of the present invention include titanium oxide, metatitanic acid, alkali metal titanate, and metal titanium. These may be used alone or may be used alone. A combination of more than one species may be used. Examples of the alkali metal titanate include lithium titanate, sodium titanate, potassium titanate, rubidium titanate, and cesium titanate.
　前記工程（１）において、工程（２）における加熱温度よりも融点の高いアルカリ金属硫酸塩の粉末をさらに混合することにより、工程（２）において、高温で溶融したアルカリ金属炭酸塩中で反応前のチタン化合物が沈殿して反応ムラが生じることが抑制される。更に、工程（２）において反応後の化合物および過剰のアルカリ金属炭酸塩の融液がアルカリ金属硫酸塩粉末に浸み込んだ状態で冷却されることにより、それらが固化するとともに収縮する際に製造容器との界面に隙間ができ、前記工程（２）において得られる生成物を製造容器から取り出しやすくすることができる。アルカリ金属硫酸塩としては、特に制限はなく、例えば、硫酸カリウム、硫酸ナトリウム等が挙げられる。 In the step (1), by further mixing an alkali metal sulfate powder having a melting point higher than the heating temperature in the step (2), the reaction in the alkali metal carbonate melted at a high temperature in the step (2) Precipitation of the titanium compound and uneven reaction are suppressed. Further, in the step (2), the compound after the reaction and the melt of the excess alkali metal carbonate are cooled in a state of being immersed in the alkali metal sulfate powder, so that they are solidified and shrunk when they are shrunk. A gap is formed at the interface with the container, and the product obtained in the step (2) can be easily taken out of the production container. The alkali metal sulfate is not particularly limited, and includes, for example, potassium sulfate and sodium sulfate.
　工程（２）は、前記工程（１）で得られた混合物を７００℃以上１５００℃以下で加熱する工程である。加熱時間は、３０分間～１００時間が好ましい。チタン化合物の粉末と過剰量のアルカリ金属炭酸塩等の粉末との混合物を７００℃以上１５００℃以下で加熱することにより、チタン化合物がアルカリ金属炭酸塩と反応して層状チタン酸塩が生成すると共に、層状チタン酸塩の結晶構造内にアルカリ金属炭酸塩を含有させることができる。なお、工程（２）において、アルカリ金属炭酸水素塩は、高温で分解してアルカリ金属炭酸塩となる。 {Circle around (2)} Step (2) is a step of heating the mixture obtained in the above step (1) at a temperature of 700 ° C. or more and 1500 ° C. or less. The heating time is preferably 30 minutes to 100 hours. By heating a mixture of a powder of a titanium compound and an excess amount of a powder of an alkali metal carbonate or the like at 700 ° C. or more and 1500 ° C. or less, the titanium compound reacts with the alkali metal carbonate to generate a layered titanate. An alkali metal carbonate can be contained in the crystal structure of the layered titanate. In the step (2), the alkali metal bicarbonate is decomposed at a high temperature to become an alkali metal carbonate.
　この反応は、炭酸ガスが脱離する反応であるため、系内の炭酸ガス濃度が高くなると反応が阻害され、目的とは別の生成物が生じるなどの不具合が生じる。そのため、加熱に使用する容器や装置は、炭酸ガスを効率的に排気できる構造や仕組みとなっていることが好ましい。例えば、容器は、通気のための切り欠きのあるものが好ましく、加熱装置としては排気を吸引して外気を少しずつ取り込む仕組みのあるものが好ましい。 た め Since this reaction is a reaction in which carbon dioxide gas is eliminated, if the concentration of carbon dioxide gas in the system becomes high, the reaction is inhibited, and problems such as the generation of a product different from the intended one occur. Therefore, it is preferable that the container and the device used for heating have a structure and a mechanism capable of efficiently exhausting carbon dioxide gas. For example, the container preferably has a cutout for ventilation, and the heating device preferably has a mechanism for sucking the exhaust gas and taking in the outside air little by little.
　前記工程（１）及び工程（２）を順次行うことによって、結晶構造内に、アルカリ金属炭酸塩およびアルカリ金属炭酸水素塩から選ばれる少なくとも１種を含有する層状チタン酸塩を含む無機イオン交換体を得ることができる。
　ここで、アルカリ金属炭酸水素塩は、工程（２）で結晶構造内に含有されたアルカリ金属炭酸塩の一部が、空気中などから供給される水分子および二酸化炭素と反応して生成したものである。
　このようにして得られる無機イオン交換体は、結晶構造内に水分子を含有していない層状チタン酸塩を含む無機イオン交換体である。本発明の無機イオン交換体は、さらに以下の工程（３）及び工程（４）を順次行うことにより、結晶構造内にさらに水分子を含有する層状チタン酸塩を含む無機イオン交換体を製造することができる。
　工程（３）：前記工程（２）で得られた無機イオン交換体を水で洗浄する工程
　工程（４）：前記工程（３）で洗浄後の無機イオン交換体を乾燥する工程 An inorganic ion exchanger containing a layered titanate containing at least one selected from alkali metal carbonates and alkali metal bicarbonates in the crystal structure by sequentially performing the steps (1) and (2). Can be obtained.
Here, the alkali metal bicarbonate is formed by reacting a part of the alkali metal carbonate contained in the crystal structure in step (2) with water molecules and carbon dioxide supplied from the air or the like. It is.
The inorganic ion exchanger obtained in this manner is an inorganic ion exchanger containing a layered titanate containing no water molecule in the crystal structure. The inorganic ion exchanger of the present invention further performs the following steps (3) and (4) in order to produce an inorganic ion exchanger containing a layered titanate further containing a water molecule in the crystal structure. be able to.
Step (3): a step of washing the inorganic ion exchanger obtained in the step (2) with water Step (4): a step of drying the inorganic ion exchanger after the washing in the step (3)
　前記工程（３）は、前記工程（２）で得られた無機イオン交換体を水で洗浄し、無機イオン交換体の結晶構造の外にある余分なアルカリ金属炭酸塩を除去する工程である。前記工程（２）で得られた無機イオン交換体を水で洗浄することにより、無機イオン交換体の結晶構造の外にある余分なアルカリ金属炭酸塩を除去すると同時に、層状チタン酸塩の結晶構造内に水分子が取り込まれ、チタン酸の層間距離がさらに広がった構造となる。 The step (3) is a step of washing the inorganic ion exchanger obtained in the step (2) with water to remove excess alkali metal carbonate outside the crystal structure of the inorganic ion exchanger. By washing the inorganic ion exchanger obtained in the step (2) with water, excess alkali metal carbonate outside the crystal structure of the inorganic ion exchanger is removed, and at the same time, the crystal structure of the layered titanate is removed. Water molecules are taken into the inside, and the interlayer distance of the titanic acid is further increased.
　洗浄の効率を上げるために、前記工程（２）で得られた生成物は、工程（３）の前に解砕しておくことが好ましい。解砕装置としては、ジョークラッシャー、ロールクラッシャー、ハンマーミルなどを用いることができる。
　前記工程（３）において、イオン交換体の結晶構造内に存在するアルカリ金属炭酸塩等が除去されないように、水での洗浄は穏やかにすることが好ましい。即ち、適量の水で洗浄したり、高温でない水で洗浄したりすることで、結晶構造内での水分子をより多く保持することができる。例えば、水での洗浄は、工程（２）の生成物の重量に対して３～１０倍の重量の常温の水でスラリー化し、次いで脱水し、更に得られた脱水ケーキの重量に対して３～１０倍の重量の常温の水を通水する方法、或いは、前記スラリー化と脱水を２～３回繰り返す方法が好ましい。 In order to increase the washing efficiency, the product obtained in the step (2) is preferably pulverized before the step (3). As a crusher, a jaw crusher, a roll crusher, a hammer mill, or the like can be used.
In the step (3), the washing with water is preferably gentle so that the alkali metal carbonate and the like existing in the crystal structure of the ion exchanger are not removed. That is, by washing with an appropriate amount of water or washing with non-high-temperature water, more water molecules can be retained in the crystal structure. For example, washing with water involves slurrying with water at room temperature 3 to 10 times the weight of the product of step (2), then dewatering, and then 3% on the weight of the resulting dewatered cake. It is preferable to use a method of passing water of normal temperature having a weight of up to 10 times, or a method of repeating the slurrying and dehydration two to three times.
　前記工程（４）は、前記工程（３）で洗浄後の無機イオン交換体を乾燥する工程である。水分子のみを完全に除去して、アルカリ金属炭酸塩等のみを結晶構造内に残すようにしてもよいが、アルカリ金属炭酸塩等だけでなく、水分子も結晶構造内に残すようにした方が、アルカリ金属炭酸塩等のみを結晶構造内に残すよりは、チタン酸の層間をより広くすることができ、本発明の技術的効果の発現を最大化することができる。したがって、前記工程（３）で層状チタン酸塩の結晶構造内に取り込まれた水分子を、前記工程（４）により前記無機イオン交換体を乾燥させてもなお結晶構造内に残存させるために、乾燥条件は、穏やかにすることが好ましい。乾燥条件としては、１００℃以下での温風乾燥が好ましく、５０℃以下での温風乾燥がより好ましい。
　前記工程（３）および前記工程（４）においては、結晶構造内に取り込まれた水分子の一部と、結晶構造内に存在するアルカリ金属炭酸塩の一部と、水中または空気中から供給される二酸化炭素とが反応し、アルカリ金属炭酸水素塩が更に生成することがある。 The step (4) is a step of drying the inorganic ion exchanger after the washing in the step (3). It may be possible to completely remove only water molecules and leave only alkali metal carbonates and the like in the crystal structure, but it is preferable to leave not only alkali metal carbonates and the like but also water molecules in the crystal structure. However, as compared with leaving only the alkali metal carbonate or the like in the crystal structure, the interlayer of the titanic acid can be made wider, and the technical effects of the present invention can be maximized. Therefore, in order to allow the water molecules incorporated in the crystal structure of the layered titanate in the step (3) to remain in the crystal structure even after the inorganic ion exchanger is dried in the step (4), The drying conditions are preferably mild. As drying conditions, hot air drying at 100 ° C. or lower is preferable, and hot air drying at 50 ° C. or lower is more preferable.
In the step (3) and the step (4), a part of the water molecule taken into the crystal structure, a part of the alkali metal carbonate present in the crystal structure, and the water are supplied from water or air. Reacts with the carbon dioxide to form alkali metal bicarbonate.
　工程（４）で得られた無機イオン交換体の乾燥物は、必要に応じ解砕または粉砕して粉末状とすることができる。また、得られた無機イオン交換体の粉末を、造粒助剤を用いて造粒処理を行い、造粒体としてもよい。造粒処理方法としては、特に制限はなく、転動造粒法、流動層造粒法、混合撹拌造粒法、押出造粒法、融解造粒法、噴霧造粒法、圧縮造粒法、粉砕造粒法等が挙げられる。造粒助剤としては、例えば、ベントナイト、アタパルジャイト、セピオライト、アロフェン、ハロイサイト、イモゴライト、カオリナイト等の粘土鉱物；ケイ酸ナトリウム、ケイ酸カルシウム、ケイ酸マグネシウム、メタケイ酸ナトリウム、メタケイ酸カルシウム、メタケイ酸マグネシウム、メタケイ酸アルミン酸ナトリウム、メタケイ酸アルミン酸カルシウム、メタケイ酸アルミン酸マグネシウムなどのケイ酸塩化合物；ポリビニルアルコール、カルボキシメチルセルロース、ショ糖脂肪酸エステル、ブタジエン－スチレンラテックス、フッ素樹脂などの有機高分子等が挙げられる。これらは１種を単独で用いてもよいし、２種以上を混合して用いてもよい。 乾燥 The dried product of the inorganic ion exchanger obtained in the step (4) can be pulverized or pulverized to a powder as required. Further, the obtained powder of the inorganic ion exchanger may be subjected to a granulation treatment using a granulation aid to form a granulated body. There is no particular limitation on the granulation method, and the rolling granulation method, fluidized bed granulation method, mixing stirring granulation method, extrusion granulation method, melt granulation method, spray granulation method, compression granulation method, A pulverization granulation method and the like can be mentioned. Examples of the granulation aid include clay minerals such as bentonite, attapulgite, sepiolite, allophane, halloysite, imogolite, kaolinite; sodium silicate, calcium silicate, magnesium silicate, sodium metasilicate, calcium metasilicate, and metasilicate. Silicate compounds such as magnesium, sodium metasilicate aluminate, calcium metasilicate aluminate, magnesium metasilicate aluminate; organic polymers such as polyvinyl alcohol, carboxymethyl cellulose, sucrose fatty acid ester, butadiene-styrene latex, and fluororesin Is mentioned. These may be used alone or in a combination of two or more.
＜放射性ストロンチウムを含有する水の浄化方法＞
　本発明の無機イオン交換体を用いて、放射性物質を含有する水、具体的には放射性ストロンチウムを含有する水を浄化し、水中に含まれる放射性ストロンチウムを除去することができる。前記放射性ストロンチウムを含む水の浄化方法は、本発明の無機イオン交換体に放射性ストロンチウムを含有する水を接触させる工程と、前記接触後に得られた水から前記無機イオン交換体を分離する工程とを順次行うことにより実施することができる。 <Method of purifying water containing radioactive strontium>
Using the inorganic ion exchanger of the present invention, water containing a radioactive substance, specifically, water containing radioactive strontium can be purified, and radioactive strontium contained in the water can be removed. The method for purifying water containing radioactive strontium includes a step of contacting water containing radioactive strontium with the inorganic ion exchanger of the present invention, and a step of separating the inorganic ion exchanger from water obtained after the contact. It can be carried out by performing it sequentially.
　本発明の放射性ストロンチウムを含有する水の浄化方法において、本発明の無機イオン交換体に放射性ストロンチウムを含有する水を接触させる方法は、特に制限はなく、例えば、前記無機イオン交換体をカラム等の容器に充填して、放射性ストロンチウムを含む水を通塔させる方法や、放射性ストロンチウムを含有する水に、本発明の無機イオン交換体を分散させる方法等が挙げられる。 In the method for purifying water containing radioactive strontium of the present invention, the method of contacting water containing radioactive strontium with the inorganic ion exchanger of the present invention is not particularly limited, for example, the inorganic ion exchanger may be a column or the like. Examples include a method of filling a container and passing water containing radioactive strontium, and a method of dispersing the inorganic ion exchanger of the present invention in water containing radioactive strontium.
　前記放射性ストロンチウムを含有する水の浄化方法において、本発明の無機イオン交換体に放射性ストロンチウムを含有する水を接触後に得られた水から前記無機イオン交換体を分離する方法は、本発明の無機イオン交換体に放射性ストロンチウムを含有する水を接触後に得られた水から前記無機イオン交換体を分離できれば特に制限はなく、例えば、前記無機イオン交換体をカラム等の容器に充填して、放射性ストロンチウムを含有する水を通塔させる場合は、そのまま通過した水を分取すればよく、放射性ストロンチウムを含有する水に、本発明の無機イオン交換体を分散させる場合は、分散された無機イオン交換体を、上部または下部にストレーナー構造を有する容器を用いて無機イオン交換体を前記接触後の水から分離すること等により行うことができる。 In the method for purifying water containing radioactive strontium, the method for separating the inorganic ion exchanger from water obtained after contacting the water containing radioactive strontium with the inorganic ion exchanger of the present invention comprises the inorganic ion exchanger of the present invention. There is no particular limitation as long as the inorganic ion exchanger can be separated from water obtained after contacting water containing radioactive strontium with the exchanger.For example, by filling the inorganic ion exchanger into a container such as a column, the radioactive strontium is added. When passing the containing water, the passed water may be fractionated as it is, and when the inorganic ion exchanger of the present invention is dispersed in the water containing radioactive strontium, the dispersed inorganic ion exchanger is used. Separating the inorganic ion exchanger from the contacted water using a container having a strainer structure at the top or bottom, etc. It can be carried out more.
　以下に実施例を比較例と共に挙げて本発明を詳細に説明するが、本発明はそれら実施例によって何ら限定されるものではない。以下の実施例と比較例において、得られたチタン酸塩の組成および物性の測定は下記によった。 The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. In the following Examples and Comparative Examples, the composition and physical properties of the obtained titanate were measured as described below.
＜金属元素組成分析＞
　フッ酸と硝酸と過塩素酸との混酸を用い、テフロン（登録商標）製耐圧密閉容器内で１４０℃に加熱して試料を分解し、硝酸溶液としてから、ＩＣＰ－ＭＳにて金属元素の含有量を分析した。 <Metal element composition analysis>
Using a mixed acid of hydrofluoric acid, nitric acid, and perchloric acid, the sample is decomposed by heating to 140 ° C. in a pressure-resistant sealed container made of Teflon (registered trademark) to form a nitric acid solution, and then containing a metal element by ICP-MS. The amount was analyzed.
＜Ｃ、Ｈ含有量測定＞
　ＪＩＳ　Ｍ　８８１９の方法に従い、固体中炭素水素分析計を用いて、燃焼温度９２０℃の条件にて、ＣおよびＨの含有量を分析した。 <C, H content measurement>
In accordance with the method of JIS M 8819, the contents of C and H were analyzed under the condition of a combustion temperature of 920 ° C. using a carbon-hydrogen analyzer in solid.
＜粉末Ｘ線回折＞
　（株）リガク製の粉末Ｘ線回折装置ＲＩＮＴ２２００ ＵＬＴＩＭＡ ＩＶを用い、線源
として、Ｃｕ管球［波長１．５４１８４１Å（Ｋα）］を用いて、角度（２θ）１°から２０°までの回折パターンを得た。そして、この角度範囲に回折ピークを有さないアナターゼ型二酸化チタン粉末の測定で得られたバックグラウンド曲線をフィッテングさせて補正した上で、最低角度（２θ）の回折ピークの位置および半値幅を求めた。 <X-ray powder diffraction>
Using a powder X-ray diffractometer RINT2200 ULTIMA IV manufactured by Rigaku Corporation and a Cu tube [wavelength 1.541841 ° (Kα)] as a radiation source, a diffraction pattern at an angle (2θ) of 1 ° to 20 °. I got Then, after correcting the background curve obtained by measuring the anatase type titanium dioxide powder having no diffraction peak in this angle range by fitting, the position and the half width of the diffraction peak at the lowest angle (2θ) are obtained. Was.
＜ＴＧ－ＭＳ分析＞
　（株）リガク製の粉示差熱天秤－光イオン化質量分析同時測定システム　Ｔｈｅｒｍｏ　Ｍａｓｓ　Ｐｈｏｔｏを用い、室温から毎分１０℃で２００℃まで昇温したときの発生ガスを分析した。そして、（株）リガク発行のＴｈｅｒｍｏ　Ｍａｓｓ　Ｐｈｏｔｏ測定データ集に記載の無機ガスの簡易定量法を用いて、発生ガス量を求めた。 <TG-MS analysis>
Using a powder differential thermal balance-photoionization mass spectrometry simultaneous measurement system Thermo Mass Photo manufactured by Rigaku Corporation, the gas generated when the temperature was raised from room temperature to 200 ° C. at 10 ° C. per minute was analyzed. Then, the amount of generated gas was determined using a simple quantitative method of inorganic gas described in Thermo Mass Photo measurement data collection issued by Rigaku Corporation.
＜１３Ｃ－ＮＭＲ＞
　ＪＥＯＬ　ＲＥＳＯＮＡＮＣＥ製のＪＮＭ－ＥＣＡ６００を用い、共鳴周波数１５０ＭＨｚとし、回転数１０ｋＨｚのＭＡＳ（シングルパルス）にて固体高分解能１３Ｃ－ＮＭＲ測定を行った。炭酸塩ピークの同定は、試薬炭酸塩の測定により得られた共鳴ピーク位置との比較により行った。 < 13 C-NMR>
Using a JNM-ECA600 manufactured by JEOL RESONANCE, solid-state high-resolution 13 C-NMR measurement was performed using MAS (single pulse) with a resonance frequency of 150 MHz and a rotation speed of 10 kHz. The carbonate peak was identified by comparison with the resonance peak position obtained by measurement of the reagent carbonate.
＜ストロンチウム吸着試験＞
　脱イオン水１Ｌに、塩化ストロンチウム（ＳｒＣｌ２）０．０９０５ｇを溶解させ、次いで４８％水酸化ナトリウム水溶液６．２５ｇを加えてよく混ぜ、試験溶液とした。この試験溶液５０ｍｌに、試料０．０５ｇを入れ、ラボシェーカーで１０時間振とうさせた。
　振とう後、試験溶液をメンブレンフィルターにより濾過し、濾液中の残留ストロンチウム量をＩＣＰ－ＯＥＳ（パーキンエルマー製Ｏｐｔｉｍａ　８３００）を用いて定量し、分配係数Ｋｄ（ｍｌ／ｇ）を下記式により求めた。 <Strontium adsorption test>
In 1 L of deionized water, 0.0905 g of strontium chloride (SrCl 2 ) was dissolved, and then 6.25 g of a 48% aqueous sodium hydroxide solution was added and mixed well to prepare a test solution. 0.05 g of the sample was placed in 50 ml of the test solution, and shaken for 10 hours using a laboratory shaker.
After shaking, the test solution was filtered through a membrane filter, the amount of residual strontium in the filtrate was quantified using ICP-OES (Perkin Elmer Optima 8300), and the distribution coefficient Kd (ml / g) was determined by the following equation. .
Figure JPOXMLDOC01-appb-M000002
Figure JPOXMLDOC01-appb-M000002
（実施例１）
　無水炭酸カリウム粉末２７．６ｇ（Ｋとして４００ｍｍｏｌ）と、硫酸カリウム粉末３５ｇと、アナターゼ型二酸化チタン粉末８．０ｇ（Ｔｉとして１００ｍｍｏｌ）とを乳鉢でよく混合し、アルミナルツボに入れて９５０℃で２０時間加熱した。生成物を乳鉢で粗解砕し、５００ｇの脱イオン水に懸濁させ、１時間撹拌した。次いで、減圧ろ過し、脱水ケーキとなったところで、減圧ろ過を続けながら、１００ｇの脱イオン水でリンス洗浄した。脱水したウエットケーキに、２０ｍｌのメタノールを通液して水と置換し、次いで、常温で風乾し、白色の粉末を得た。得られた白色粉末について、前記金属元素組成分析とＣ、Ｈ含有量測定結果を行ったところ、組成は次の式で表せることが分かった。
　０．２４Ｋ２Ｏ・ＴｉＯ２・１．０Ｈ２Ｏ・０．０８６Ｋ２ＣＯ３ (Example 1)
27.6 g of anhydrous potassium carbonate powder (400 mmol as K), 35 g of potassium sulfate powder and 8.0 g of anatase-type titanium dioxide powder (100 mmol as Ti) are well mixed in a mortar, put in an alumina crucible and placed at 950 ° C. for 20 minutes. Heated for hours. The product was coarsely crushed in a mortar, suspended in 500 g of deionized water and stirred for 1 hour. Next, the mixture was filtered under reduced pressure to form a dehydrated cake, and rinsed with 100 g of deionized water while continuing filtration under reduced pressure. 20 ml of methanol was passed through the dehydrated wet cake to replace water, and then air-dried at room temperature to obtain a white powder. The obtained white powder was subjected to the metal element composition analysis and the C and H content measurement results, and it was found that the composition could be represented by the following equation.
0.24K 2 O · TiO 2 · 1.0H 2 O · 0.086K 2 CO 3
　次に、得られた白色粉末について、前記粉末Ｘ線回折測定を行ったところ、図１に示す回折パターンが得られた。回折角８°以下に極大点を有するブロードなピークが観察され、層状物質の層間が不規則に広がった構造であることが示唆された。最低角回折線のピーク位置は６．８°で、その半値幅は２θで５．２°であった。
　さらに、得られた白色粉末について、前記ＴＧ－ＭＳ分析を行ったところ、１３％の重量減少があり、発生ガスはＨ２Ｏと同定された。
　また、得られた白色粉末について、１３Ｃ－ＮＭＲを分析したところ、図２に示すチャートが得られ、化学シフトが１７０ｐｐｍの位置に炭酸カリウムに帰属される鋭いピークが得られた。
　さらに、前記ストロンチウム吸着試験を行ったところ、分配係数Ｋｄは１００万ｍｌ／ｇであった。
　以上の分析結果を表１に示す。表１に示した結果より、上記で得られた白色粉末は、結晶構造内に炭酸カリウムおよび炭酸水素カリウムからなる群から選ばれる少なくとも１種と水とを含有する、低結晶性の層状チタン酸カリウムであると推定され、優れたストロンチウム吸着能を有していた。 Next, the obtained white powder was subjected to the powder X-ray diffraction measurement, and the diffraction pattern shown in FIG. 1 was obtained. A broad peak having a maximum point at a diffraction angle of 8 ° or less was observed, suggesting a structure in which the layers of the layered material were irregularly spread. The peak position of the lowest angle diffraction line was 6.8 °, and the half value width was 5.2 ° at 2θ.
Further, the obtained white powder was subjected to the TG-MS analysis. As a result, the weight was reduced by 13%, and the generated gas was identified as H 2 O.
When the obtained white powder was analyzed by 13 C-NMR, a chart shown in FIG. 2 was obtained, and a sharp peak attributed to potassium carbonate was obtained at a position where the chemical shift was 170 ppm.
Further, when the strontium adsorption test was performed, the distribution coefficient Kd was 1,000,000 ml / g.
Table 1 shows the results of the above analysis. From the results shown in Table 1, the white powder obtained above is a low-crystalline layered titanic acid containing water and at least one selected from the group consisting of potassium carbonate and potassium bicarbonate in the crystal structure. It was presumed to be potassium and had excellent strontium adsorption ability.
（実施例２）
　無水炭酸カリウム粉末１０．４ｇ（Ｋとして１５０ｍｍｏｌ）と、硫酸カリウム粉末１３ｇと、メタチタン酸粉末９．８ｇ（Ｔｉとして１００ｍｍｏｌ）とを乳鉢でよく混合し、アルミナルツボに入れて９００℃で２０時間加熱した。生成物を乳鉢で粗解砕し、３５０ｇの脱イオン水に懸濁させ、１時間撹拌した。次いで、減圧ろ過し、脱水ケーキとなったところで、減圧ろ過を続けながら、１００ｇの脱イオン水でリンス洗浄した。洗浄したケーキを、５０℃で温風乾燥し、白色粉末を得た。得られた白色粉末について、金属元素組成分析、Ｃ、Ｈ含有量測定、粉末Ｘ線回折、ＴＧ－ＭＳ分析、１３Ｃ－ＮＭＲ及びストロンチウム吸着試験を行った。その結果を表１に示す。表１に示した結果より、得られた白色粉末は、結晶構造内に炭酸カリウムおよび炭酸水素カリウムからなる群から選ばれる少なくとも１種と水とを含有する、低結晶性の層状チタン酸カリウムであると推定され、優れたストロンチウム吸着能を有していた。 (Example 2)
10.4 g of anhydrous potassium carbonate powder (150 mmol as K), 13 g of potassium sulfate powder and 9.8 g of metatitanic acid powder (100 mmol as Ti) are well mixed in a mortar, put in an alumina crucible and heated at 900 ° C. for 20 hours. did. The product was coarsely crushed in a mortar, suspended in 350 g of deionized water and stirred for 1 hour. Next, the mixture was filtered under reduced pressure to form a dehydrated cake, and rinsed with 100 g of deionized water while continuing filtration under reduced pressure. The washed cake was dried with hot air at 50 ° C. to obtain a white powder. The obtained white powder was subjected to metal element composition analysis, C and H content measurement, powder X-ray diffraction, TG-MS analysis, 13 C-NMR and strontium adsorption test. Table 1 shows the results. From the results shown in Table 1, the obtained white powder was a low-crystalline layered potassium titanate containing water and at least one selected from the group consisting of potassium carbonate and potassium bicarbonate in the crystal structure. It was presumed that the compound had excellent strontium adsorption ability.
（実施例３）
　無水炭酸ナトリウム粉末２１．２ｇを水２００ｍｌに溶解し、常温で撹拌しながら、１０重量％硫酸チタン水溶液２４０ｇ（Ｔｉとして１００ｍｍｏｌ）を３０分間かけて滴下した。生成した水酸化チタンを遠心分離で回収し、１００℃で蒸発乾固させた後、乳鉢ですり潰して水酸化チタン粉末１１．３ｇを得た。この水酸化チタン粉末全量と、無水炭酸ナトリウム粉末１５．９ｇ（Ｎａとして３００ｍｍｏｌ）と、硫酸カリウム粉末２５ｇとを乳鉢でよく混合し、アルミナルツボに入れて９００℃で２０時間加熱した。生成物を乳鉢で粗解砕し、５００ｇの脱イオン水に懸濁させ、１時間撹拌した。次いで、減圧ろ過し、脱水ケーキとなったところで、減圧ろ過を続けながら、１００ｇの脱イオン水でリンス洗浄した。洗浄したケーキを、５０℃で温風乾燥し、白色粉末を得た。得られた白色粉末について、金属元素組成分析、Ｃ、Ｈ含有量測定、粉末Ｘ線回折、ＴＧ－ＭＳ分析、１３Ｃ－ＮＭＲ及びストロンチウム吸着試験を行った。その結果を表１に示す。表１に示した結果より、得られた白色粉末は、結晶構造内に炭酸ナトリウムおよび炭酸水素ナトリウムからなる群から選ばれる少なくとも１種と水とを含有する、低結晶性の層状チタン酸ナトリウムであると推定され、優れたストロンチウム吸着能を有していた。 (Example 3)
21.2 g of anhydrous sodium carbonate powder was dissolved in 200 ml of water, and 240 g (100 mmol as Ti) of a 10% by weight aqueous solution of titanium sulfate was added dropwise over 30 minutes while stirring at room temperature. The produced titanium hydroxide was recovered by centrifugation, evaporated to dryness at 100 ° C., and ground in a mortar to obtain 11.3 g of titanium hydroxide powder. The total amount of the titanium hydroxide powder, 15.9 g of anhydrous sodium carbonate powder (300 mmol as Na), and 25 g of potassium sulfate powder were mixed well in a mortar, and placed in an alumina crucible and heated at 900 ° C. for 20 hours. The product was coarsely crushed in a mortar, suspended in 500 g of deionized water and stirred for 1 hour. Next, the mixture was filtered under reduced pressure to form a dehydrated cake, and rinsed with 100 g of deionized water while continuing filtration under reduced pressure. The washed cake was dried with hot air at 50 ° C. to obtain a white powder. The obtained white powder was subjected to metal element composition analysis, C and H content measurement, powder X-ray diffraction, TG-MS analysis, 13 C-NMR and strontium adsorption test. Table 1 shows the results. From the results shown in Table 1, the obtained white powder is a low-crystalline layered sodium titanate containing water and at least one selected from the group consisting of sodium carbonate and sodium bicarbonate in the crystal structure. It was presumed that the compound had excellent strontium adsorption ability.
（実施例４）
　無水炭酸リチウム粉末１４．９ｇを水２００ｍｌに溶解して７０℃に加熱し、撹拌しながら、１０重量％四塩化チタン水溶液１９０ｇ（Ｔｉとして１００ｍｍｏｌ）を３０分間かけて滴下した。生成した水酸化チタンを遠心分離で回収し、１００℃で蒸発乾固させた後、乳鉢ですり潰して水酸化チタン粉末１２．８ｇを得た。この水酸化チタン粉末全量と、無水炭酸リチウム粉末９．２ｇ（Ｌｉとして２５０ｍｍｏｌ）と、硫酸カリウム粉末２５ｇとを乳鉢でよく混合し、アルミナルツボに入れて９００℃で２０時間加熱した。生成物を乳鉢で粗解砕し、５００ｇの脱イオン水に懸濁させ、１時間撹拌した。次いで、減圧ろ過し、脱水ケーキとなったところで、減圧ろ過を続けながら、１００ｇの脱イオン水でリンス洗浄した。洗浄したケーキを、５０℃で温風乾燥し、白色粉末を得た。得られた白色粉末について、金属元素組成分析、Ｃ、Ｈ含有量測定、粉末Ｘ線回折、ＴＧ－ＭＳ分析、１３Ｃ－ＮＭＲ及びストロンチウム吸着試験を行った。その結果を表１に示す。表１に示した結果より、得られた白色粉末は、結晶構造内に炭酸リチウムおよび炭酸水素リチウムからなる群から選ばれる少なくとも１種と水とを含有する、低結晶性の層状構造チタン酸リチウムであると推定され、優れたストロンチウム吸着能を有していた。 (Example 4)
14.9 g of anhydrous lithium carbonate powder was dissolved in 200 ml of water, heated to 70 ° C., and 190 g (100 mmol as Ti) of a 10% by weight aqueous solution of titanium tetrachloride was added dropwise with stirring over 30 minutes. The generated titanium hydroxide was collected by centrifugation, evaporated to dryness at 100 ° C., and ground in a mortar to obtain 12.8 g of titanium hydroxide powder. The total amount of the titanium hydroxide powder, 9.2 g (250 mmol as Li) of anhydrous lithium carbonate powder and 25 g of potassium sulfate powder were mixed well in a mortar, and placed in an alumina crucible and heated at 900 ° C. for 20 hours. The product was coarsely crushed in a mortar, suspended in 500 g of deionized water and stirred for 1 hour. Next, the mixture was filtered under reduced pressure to form a dehydrated cake, and rinsed with 100 g of deionized water while continuing the reduced pressure filtration. The washed cake was dried with hot air at 50 ° C. to obtain a white powder. The obtained white powder was subjected to metal element composition analysis, C and H content measurement, powder X-ray diffraction, TG-MS analysis, 13 C-NMR and strontium adsorption test. Table 1 shows the results. From the results shown in Table 1, the obtained white powder is a low-crystalline layered structure lithium titanate containing water and at least one selected from the group consisting of lithium carbonate and lithium hydrogen carbonate in the crystal structure. And had excellent strontium adsorption ability.
（比較例１）
　無水炭酸カリウム粉末３．５ｇ（Ｋとして５０ｍｍｏｌ）と、アナターゼ型二酸化チタン粉末８．０ｇ（Ｔｉとして１００ｍｍｏｌ）をと乳鉢でよく混合し、アルミナルツボに入れて８００℃で４８時間加熱し、白色粉末を得た。ただし、加熱１６時間毎に一旦冷却し、乳鉢でよくすり潰した。得られた白色粉末について、金属元素組成分析、Ｃ、Ｈ含有量測定、粉末Ｘ線回折、ＴＧ－ＭＳ分析、１３Ｃ－ＮＭＲ及びストロンチウム吸着試験を行った。その結果を表１に示す。表１に示した結果より、得られた白色粉末は、結晶構造内にアルカリ金属炭酸塩およびアルカリ金属炭酸酸塩を含有しない、層状四チタン酸カリウムであると推定された。 (Comparative Example 1)
3.5 g of anhydrous potassium carbonate powder (50 mmol as K) and 8.0 g of anatase-type titanium dioxide powder (100 mmol as Ti) are mixed well in a mortar and heated in an alumina crucible at 800 ° C. for 48 hours to give a white powder. I got However, the mixture was cooled once every 16 hours of heating, and ground well in a mortar. The obtained white powder was subjected to metal element composition analysis, C and H content measurement, powder X-ray diffraction, TG-MS analysis, 13 C-NMR and strontium adsorption test. Table 1 shows the results. From the results shown in Table 1, it was estimated that the obtained white powder was layered potassium tetratitanate containing no alkali metal carbonate or alkali metal carbonate in the crystal structure.
（比較例２）
　比較例１で得られたチタン酸カリウム１ｇを６０ｇの脱イオン水に懸濁させ、４８時間撹拌した。次いで、減圧ろ過し、脱水ケーキとなったところで、減圧ろ過を続けながら、１０ｇの脱イオン水でリンス洗浄した。洗浄したケーキを、室温で風乾し、白色粉末を得た。得られた白色粉末について、金属元素組成分析、Ｃ、Ｈ含有量測定、粉末Ｘ線回折、ＴＧ－ＭＳ分析、１３Ｃ－ＮＭＲ及びストロンチウム吸着試験を行った。その結果を表１に示す。表１に示した結果より、得られた白色粉末は、層状結晶である四チタン酸カリウムの層間から一部のカリウムが溶出するとともに、水とオキソニウムイオンとが導入され、層間が規則的に広がっているが、結晶構造内にアルカリ金属炭酸塩およびアルカリ金属炭酸酸塩を含有しない、層状チタン酸カリウムであると推定された。 (Comparative Example 2)
1 g of the potassium titanate obtained in Comparative Example 1 was suspended in 60 g of deionized water and stirred for 48 hours. Then, the mixture was filtered under reduced pressure to form a dehydrated cake, and rinsed with 10 g of deionized water while continuing the reduced pressure filtration. The washed cake was air-dried at room temperature to obtain a white powder. The obtained white powder was subjected to metal element composition analysis, C and H content measurement, powder X-ray diffraction, TG-MS analysis, 13 C-NMR and strontium adsorption test. Table 1 shows the results. From the results shown in Table 1, in the obtained white powder, some potassium was eluted from between the layers of potassium tetratitanate, which is a layered crystal, and water and oxonium ions were introduced. It was presumed to be layered potassium titanate, which spread but did not contain alkali metal carbonate and alkali metal carbonate in the crystal structure.
（比較例３）
　無水炭酸ナトリウム粉末２１．２ｇを水２００ｍｌに溶解し、常温で撹拌しながら、１０重量％硫酸チタン水溶液２４０ｇ（Ｔｉとして１００ｍｍｏｌ）を３０分間かけて滴下した。生成した水酸化チタンを遠心分離で回収し、１００℃で蒸発乾固させた後、乳鉢ですり潰して水酸化チタン粉末１１．３ｇを得た。この水酸化チタン粉末全量と、無水炭酸ナトリウム粉末３．７ｇ（Ｎａとして７０ｍｍｏｌ）と、硫酸カリウム粉末２５ｇとを乳鉢でよく混合し、アルミナルツボに入れて９００℃で２０時間加熱した。生成物を乳鉢で粗解砕し、５００ｇの脱イオン水に懸濁させ、１時間撹拌した。次いで、減圧ろ過し、脱水ケーキとなったところで、減圧ろ過を続けながら、１００ｇの脱イオン水でリンス洗浄した。洗浄したケーキを、５０℃で温風乾燥し、白色粉末を得た。得られた白色粉末について、金属元素組成分析、Ｃ、Ｈ含有量測定、粉末Ｘ線回折、ＴＧ－ＭＳ分析、１３Ｃ－ＮＭＲ及びストロンチウム吸着試験を行った。その結果を表１に示す。表１に示した結果より、得られた白色粉末は、結晶構造内にアルカリ金属炭酸塩およびアルカリ金属炭酸酸塩を含有しない、トンネル構造のチタン酸ナトリウムであると推定された。 (Comparative Example 3)
21.2 g of anhydrous sodium carbonate powder was dissolved in 200 ml of water, and 240 g (100 mmol as Ti) of a 10% by weight aqueous solution of titanium sulfate was added dropwise over 30 minutes while stirring at room temperature. The produced titanium hydroxide was collected by centrifugation, evaporated to dryness at 100 ° C., and ground in a mortar to obtain 11.3 g of titanium hydroxide powder. The total amount of the titanium hydroxide powder, 3.7 g of anhydrous sodium carbonate powder (70 mmol as Na), and 25 g of potassium sulfate powder were mixed well in a mortar, and placed in an alumina crucible and heated at 900 ° C. for 20 hours. The product was coarsely crushed in a mortar, suspended in 500 g of deionized water and stirred for 1 hour. Next, the mixture was filtered under reduced pressure to form a dehydrated cake, and rinsed with 100 g of deionized water while continuing filtration under reduced pressure. The washed cake was dried with hot air at 50 ° C. to obtain a white powder. The obtained white powder was subjected to metal element composition analysis, C and H content measurement, powder X-ray diffraction, TG-MS analysis, 13 C-NMR and strontium adsorption test. Table 1 shows the results. From the results shown in Table 1, it was estimated that the obtained white powder was sodium titanate having a tunnel structure and containing no alkali metal carbonate or alkali metal carbonate in the crystal structure.
（比較例４）
　無水炭酸リチウム粉末１４．９ｇを水２００ｍｌに溶解して７０℃に加熱し、攪拌しながら、１０重量％四塩化チタン水溶液１９０ｇ（Ｔｉとして１００ｍｍｏｌ）を３０分間かけて滴下した。生成した水酸化チタンを遠心分離で回収し、１００℃で蒸発乾固させた後、乳鉢ですり潰して水酸化チタン粉末１２．８ｇを得た。この水酸化チタン粉末全量と、無水炭酸リチウム粉末７．４ｇ（Ｌｉとして２００ｍｍｏｌ）と、硫酸カリウム粉末２５ｇとを乳鉢でよく混合し、アルミナルツボに入れて９００℃で２０時間加熱した。生成物を乳鉢で粗解砕し、５００ｇの脱イオン水に懸濁させ、１時間攪拌した。次いで、減圧ろ過し、脱水ケーキとなったところで、減圧ろ過を続けながら、１００ｇの脱イオン水でリンス洗浄した。洗浄したケーキを、５０℃で温風乾燥し、白色粉末を得た。得られた白色粉末について、金属元素組成分析、Ｃ、Ｈ含有量測定、粉末Ｘ線回折、ＴＧ－ＭＳ分析、１３Ｃ－ＮＭＲ及びストロンチウム吸着試験を行った。その結果を表１に示す。表１に示した結果より、得られた白色粉末は、結晶構造内にアルカリ金属炭酸塩およびアルカリ金属炭酸酸塩を含有しない、層状チタン酸リチウムであると推定された。 (Comparative Example 4)
14.9 g of anhydrous lithium carbonate powder was dissolved in 200 ml of water, heated to 70 ° C., and 190 g (100 mmol as Ti) of a 10% by weight aqueous solution of titanium tetrachloride was added dropwise with stirring over 30 minutes. The generated titanium hydroxide was collected by centrifugation, evaporated to dryness at 100 ° C., and ground in a mortar to obtain 12.8 g of titanium hydroxide powder. The total amount of the titanium hydroxide powder, 7.4 g of anhydrous lithium carbonate powder (200 mmol as Li), and 25 g of potassium sulfate powder were mixed well in a mortar, and placed in an alumina crucible and heated at 900 ° C. for 20 hours. The product was coarsely crushed in a mortar, suspended in 500 g of deionized water and stirred for 1 hour. Next, the mixture was filtered under reduced pressure to form a dehydrated cake, and rinsed with 100 g of deionized water while continuing filtration under reduced pressure. The washed cake was dried with hot air at 50 ° C. to obtain a white powder. The obtained white powder was subjected to metal element composition analysis, C and H content measurement, powder X-ray diffraction, TG-MS analysis, 13 C-NMR and strontium adsorption test. Table 1 shows the results. From the results shown in Table 1, it was estimated that the obtained white powder was layered lithium titanate containing no alkali metal carbonate and no alkali metal carbonate in the crystal structure.
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
　表１に示したように、１３Ｃ－ＮＭＲの結果、実施例１～４の層状チタン酸塩は、いずれもＣＯ３に帰属できるピークが確認され、結晶構造内にアルカリ金属炭酸塩およびアルカリ金属炭酸水素塩からなる群から選ばれる少なくとも１種が含有されることが確認された。それに対して、比較例１～４のチタン酸塩は、いずれもアルカリ金属炭酸塩およびアルカリ金属炭酸水素塩を含んでいなかった。
　また、ストロンチウム吸着試験の結果、実施例１～４の層状チタン酸塩は、上記の分配係数がいずれも５００００ｍｌ／ｇ以上であり、高いストロンチウム吸着能を有することが確認された。それに対して、比較例１～４のチタン酸塩は、分配係数が５０ｍｌ／ｇ以下であり、ストロンチウム吸着能において劣っていた。 As shown in Table 1, as a result of 13 C-NMR, peaks attributable to CO 3 were confirmed in all of the layered titanates of Examples 1 to 4, and the alkali metal carbonate and the alkali metal were found in the crystal structure. It was confirmed that at least one selected from the group consisting of bicarbonates was contained. In contrast, none of the titanates of Comparative Examples 1 to 4 contained an alkali metal carbonate and an alkali metal bicarbonate.
Further, as a result of the strontium adsorption test, it was confirmed that the layered titanates of Examples 1 to 4 each had the above distribution coefficient of 50,000 ml / g or more, and had high strontium adsorption ability. On the other hand, the titanates of Comparative Examples 1 to 4 had a partition coefficient of 50 ml / g or less and were inferior in strontium adsorption ability.
　また、粉末Ｘ線回折の結果、実施例１～４の層状チタン酸塩は、いずれも回折角（２θ）が１°以上８°以下の範囲に極大点のある回折ピークを有しており、チタン酸の層間距離が広いことが確認された。それに対して、比較例１～４のチタン酸塩は、回折角（２θ）が８°を超えており、チタン酸の層間距離が、実施例１～４の層状チタン酸塩と比較して狭くなっていた。 As a result of powder X-ray diffraction, the layered titanates of Examples 1 to 4 each had a diffraction peak having a maximum point in the range of a diffraction angle (2θ) of 1 ° or more and 8 ° or less, It was confirmed that the interlayer distance of titanic acid was large. On the other hand, the titanates of Comparative Examples 1 to 4 have a diffraction angle (2θ) of more than 8 °, and the interlayer distance of titanic acid is smaller than that of the layered titanates of Examples 1 to 4. Had become.
　また、実施例１～４の層状チタン酸塩は、粉末Ｘ線回折の回折ピークの半値幅が２θで、いずれも３°以上であり、低結晶性のチタン酸塩であることが確認された。それに対して、比較例１～４のチタン酸塩は、粉末Ｘ線回折の回折ピークの半値幅が２θで、いずれも１°以下であり、結晶性が高いチタン酸塩であることが確認された。
　さらに、実施例１～４の層状チタン酸塩は、ＴＧ－ＭＳの結果、結晶構造内に水を含むことが確認された。それに対し、比較例１、２および４のチタン酸塩は、結晶構造内に水を含んでいなかった。 Further, the layered titanates of Examples 1 to 4 had a half width of the diffraction peak of powder X-ray diffraction of 2θ, which was 3 ° or more, and were confirmed to be low crystalline titanates. . On the other hand, the titanates of Comparative Examples 1 to 4 had a half width at half maximum of the diffraction peak of powder X-ray diffraction of 2θ, which was 1 ° or less, and were confirmed to be titanates with high crystallinity. Was.
Furthermore, as a result of TG-MS, it was confirmed that the layered titanates of Examples 1 to 4 contained water in the crystal structure. On the other hand, the titanates of Comparative Examples 1, 2 and 4 did not contain water in the crystal structure.
　本発明の無機イオン交換体は、高いイオン交換能を有し、放射性物質を含有する水から高い効率で放射性物質を除去することができる。このため、例えば、井戸水、湖沼水、河川水、雨水、湧水、上下水道水、工場上水・中水・下水などの各種の水などからの重金属除去、海水などからの有価資源回収、汚染土壌からの有害物質除去などにも使用することができる。 The inorganic ion exchanger of the present invention has a high ion exchange capacity and can remove radioactive substances from water containing radioactive substances with high efficiency. For this reason, for example, removal of heavy metals from various waters such as well water, lake water, river water, rainwater, spring water, sewage water, factory water supply, medium water, sewage, etc., recovery of valuable resources from seawater, pollution It can also be used to remove harmful substances from soil.

Claims (10)

  1. 　結晶構造内に、アルカリ金属炭酸塩およびアルカリ金属炭酸水素塩からなる群から選ばれる少なくとも１種を含有する層状チタン酸塩を含む無機イオン交換体。 無機 An inorganic ion exchanger containing a layered titanate containing at least one selected from the group consisting of alkali metal carbonates and alkali metal bicarbonates in the crystal structure.
  2. 　前記層状チタン酸塩が、ｘＡ２Ｏ・ＴｉＯ２・ｙＨ２Ｏ・ｚＡ２ＣＯ３（ＡはＬｉ、Ｋ、Ｎａ、Ｒｂ及びＣｓから選ばれる少なくとも１種の元素を表し、ｘ、ｙ、ｚは、それぞれ０．０２≦ｘ≦２．０、ｙ≧０．０５、ｚ≧０．０１５の数値を表す）で表されることを特徴とする請求項１に記載の無機イオン交換体。 The layered titanate is, xA 2 O · TiO 2 · yH 2 O · zA 2 CO 3 (A represents Li, K, Na, at least one element selected from Rb and Cs, x, y, z Represents the numerical values of 0.02 ≦ x ≦ 2.0, y ≧ 0.05, and z ≧ 0.015), respectively. The inorganic ion exchanger according to claim 1, wherein
  3. 　前記層状チタン酸塩が、ＣｕＫα線を用いて測定した粉末Ｘ線回折パターンにおいて、回折角（２θ）が１°以上８°以下の範囲に極大点のある回折ピークを有することを特徴とする請求項１または２に記載の無機イオン交換体。 The layered titanate has a diffraction peak having a maximum point in a range of a diffraction angle (2θ) of 1 ° or more and 8 ° or less in a powder X-ray diffraction pattern measured using CuKα radiation. Item 3. The inorganic ion exchanger according to item 1 or 2.
  4. 　前記層状チタン酸塩が、前記回折ピークの半値幅が２θで３°以上である低結晶性の化合物であることを特徴とする請求項３に記載の無機イオン交換体。 4. The inorganic ion exchanger according to claim 3, wherein the layered titanate is a low-crystalline compound having a half width of the diffraction peak of 3 ° or more at 2θ.
  5. 　ｐＨが１２以上のアルカリ性ストロンチウム水溶液に分散させたときに、下記式（１）で表される分配係数が３００００ｍｌ／ｇ以上であることを特徴とする請求項１～４のいずれか一項に記載の無機イオン交換体。
    　Ｋｄ＝Ｑｅｑ／Ｃｅｑ・・・（１）
    　（式（１）中、Ｋｄは分配係数（ｍｌ／ｇ）、Ｃｅｑは平衡到達時の水溶液中のストロンチウム濃度（ｍｏｌ／ｍｌ）、Ｑｅｑは平衡到達時の無機イオン交換体の単位重量当たりのストロンチウム吸着量（ｍｏｌ／ｇ）をそれぞれ表す）     The method according to any one of claims 1 to 4, wherein when dispersed in an aqueous alkaline strontium solution having a pH of 12 or more, a distribution coefficient represented by the following formula (1) is 30000 ml / g or more. Inorganic ion exchanger.
    Kd = Qeq / Ceq (1)
    (In the formula (1), Kd is the partition coefficient (ml / g), Ceq is the strontium concentration in the aqueous solution when the equilibrium is reached (mol / ml), and Qeq is strontium per unit weight of the inorganic ion exchanger when the equilibrium is reached. (Denotes the adsorption amount (mol / g), respectively)
  6. 　請求項１～５のいずれか一項に記載の無機イオン交換体の製造方法であって、以下の工程（１）及び工程（２）を順次行うことを特徴とする無機イオン交換体の製造方法。
    　工程（１）：チタン化合物の粉末と過剰量の、アルカリ金属炭酸塩およびアルカリ金属炭酸水素塩からなる群から選ばれる少なくとも１種の粉末とを混合する工程
    　工程（２）：前記工程（１）で得られた混合物を７００℃以上１５００℃以下で加熱する工程     The method for producing an inorganic ion exchanger according to any one of claims 1 to 5, wherein the following steps (1) and (2) are sequentially performed. .
    Step (1): mixing a titanium compound powder with an excess amount of at least one powder selected from the group consisting of alkali metal carbonates and alkali metal bicarbonates Step (2): the step (1) Heating the mixture obtained in the above at a temperature of 700 ° C. or more and 1500 ° C. or less
  7. 　さらに以下の工程（３）及び工程（４）を順次行うことを特徴とする請求項６に記載の無機イオン交換体の製造方法。
    　工程（３）：前記工程（２）で得られた無機イオン交換体を水で洗浄する工程
    　工程（４）：前記工程（３）で洗浄後の無機イオン交換体を乾燥する工程     The method for producing an inorganic ion exchanger according to claim 6, wherein the following steps (3) and (4) are further performed sequentially.
    Step (3): a step of washing the inorganic ion exchanger obtained in the step (2) with water Step (4): a step of drying the inorganic ion exchanger after the washing in the step (3)
  8. 　前記チタン化合物が、酸化チタン、メタチタン酸、アルカリ金属チタン酸塩、および金属チタンからなる群から選ばれる少なくとも１種であることを特徴とする請求項６又は７に記載の無機イオン交換体の製造方法。 The production of an inorganic ion exchanger according to claim 6, wherein the titanium compound is at least one selected from the group consisting of titanium oxide, metatitanic acid, alkali metal titanate, and metal titanium. Method.
  9. 　前記工程（１）において、アルカリ金属硫酸塩の粉末をさらに混合することを特徴とする請求項６～８のいずれか一項に記載の無機イオン交換体の製造方法。 The method for producing an inorganic ion exchanger according to any one of claims 6 to 8, wherein in the step (1), a powder of an alkali metal sulfate is further mixed.
  10. 　請求項１～５のいずれか一項に記載の無機イオン交換体に、放射性ストロンチウムを含有する水を接触させる工程と、前記接触後の水から前記無機イオン交換体を分離する工程とを順次行うことを特徴とする、放射性ストロンチウムを含有する水の浄化方法。 The step of contacting the inorganic ion exchanger according to any one of claims 1 to 5 with water containing radioactive strontium, and the step of separating the inorganic ion exchanger from water after the contact. A method for purifying water containing radioactive strontium.
PCT/JP2019/028032 2018-07-17 2019-07-17 Inorganic ion exchanger, method for producing same and method for purifying water containing radioactive strontium WO2020017538A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP2020531334A JP7400716B2 (en) 2018-07-17 2019-07-17 Inorganic ion exchanger and its manufacturing method, and method for purifying water containing radioactive strontium

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2018134428 2018-07-17
JP2018-134428 2018-07-17

Publications (1)

Publication Number Publication Date
WO2020017538A1 true WO2020017538A1 (en) 2020-01-23

Family

ID=69164900

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/JP2019/028032 WO2020017538A1 (en) 2018-07-17 2019-07-17 Inorganic ion exchanger, method for producing same and method for purifying water containing radioactive strontium

Country Status (2)

Country Link
JP (1) JP7400716B2 (en)
WO (1) WO2020017538A1 (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114689830B (en) * 2022-05-06 2023-05-26 华电电力科学研究院有限公司 Bicarbonate exchange capacity detection method and device for anion resin
CN115504504B (en) * 2022-11-07 2023-07-28 攀钢集团研究院有限公司 Reducing impurities in meta-titanic acid method for copper element content

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH07108178A (en) * 1993-08-20 1995-04-25 Toagosei Co Ltd Production of granular inorganic ion exchanger
JP2000502595A (en) * 1995-12-22 2000-03-07 イヴォ パワー エンジニアリング オサケ ユキチュア Granular titanate ion exchanger and method for producing the same
WO2017086056A1 (en) * 2015-11-18 2017-05-26 国立大学法人香川大学 Strontium ion adsorbent and method for producing same
JP2017209594A (en) * 2016-05-23 2017-11-30 株式会社クボタ Ion-exchange material, ion exchanger, ion adsorption device, water treatment system, production method of ion-exchange material, and production method of ion exchanger

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH07108178A (en) * 1993-08-20 1995-04-25 Toagosei Co Ltd Production of granular inorganic ion exchanger
JP2000502595A (en) * 1995-12-22 2000-03-07 イヴォ パワー エンジニアリング オサケ ユキチュア Granular titanate ion exchanger and method for producing the same
WO2017086056A1 (en) * 2015-11-18 2017-05-26 国立大学法人香川大学 Strontium ion adsorbent and method for producing same
JP2017209594A (en) * 2016-05-23 2017-11-30 株式会社クボタ Ion-exchange material, ion exchanger, ion adsorption device, water treatment system, production method of ion-exchange material, and production method of ion exchanger

Also Published As

Publication number Publication date
JPWO2020017538A1 (en) 2021-08-02
JP7400716B2 (en) 2023-12-19

Similar Documents

Publication Publication Date Title
Manohar et al. Adsorption performance of Al-pillared bentonite clay for the removal of cobalt (II) from aqueous phase
Liu et al. Synthesis of zeolite P1 from fly ash under solvent-free conditions for ammonium removal from water
Ekka et al. Fluoride removal in waters using ionic liquid-functionalized alumina as a novel adsorbent
Yang et al. Effect of pH, ionic strength and temperature on sorption of Pb (II) on NKF-6 zeolite studied by batch technique
US20040108275A1 (en) Arsenic removal media
CN103551104B (en) Preparation method of grading magnesium and aluminum hydrotalcite capable of adsorbing Cr(VI)
Dhongde et al. Development of nanohybrid adsorbent for defluoridation from aqueous systems
WO2020017538A1 (en) Inorganic ion exchanger, method for producing same and method for purifying water containing radioactive strontium
CN102502913A (en) Method for removing anion pollutants from water
JP2010235437A (en) Titanium oxide/layered double hydroxide composite and method for producing the same
CN103303996B (en) Application of activated aluminum oxide defluorination adsorbing material with different surface features
Lee et al. Kinetic and isothermal adsorption properties of strontium and cesium ions by zeolitic materials synthesized from Jeju volcanic rocks
CN113231033A (en) Preparation method of organic acid radical ion column-supported hydrotalcite-like adsorbent
Ahmed et al. Characterization and application of kaolinite clay as solid phase extractor for removal of copper ions from environmental water samples
CN101663241B (en) Porous iron oxide, process for producing the same, and method of treating water
US20180162746A1 (en) Method of removing dissolved silica from waste water
JP4617476B2 (en) Method for removing potassium ions
Wang et al. Synthesis of zeolite and aluminum-modified zeolite from lake sediment for simultaneous immobilization of cationic and anionic pollutants in lakes
JP6708663B2 (en) Method for treating radioactive liquid waste containing radioactive cesium and radioactive strontium
WO2019009301A1 (en) Silicotitanate molded body, method for producing same, cesium and/or strontium adsorbent containing silicotitanate molded body, and decontamination method for radioactive waste liquid using said adsorbent
JPS6036831B2 (en) Treatment method for water containing arsenic and silica
JP7398049B2 (en) Processing method for waste liquid containing strontium
JPH1072213A (en) Production of granular zeolite and nitrogen-containing soil conditioner from incineration ash of sewage sludge
JP4072624B2 (en) Specific alkali metal ion adsorbent and method for producing high purity lithium or high purity cesium
JP7310222B2 (en) Strontium adsorbent and method for producing the same

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 19837569

Country of ref document: EP

Kind code of ref document: A1

ENP Entry into the national phase

Ref document number: 2020531334

Country of ref document: JP

Kind code of ref document: A

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 19837569

Country of ref document: EP

Kind code of ref document: A1