JP2016195981A - Adsorbent and production method of adsorbent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adsorbent excellent in adsorption/removal properties of Cs and/or Sr even in sea water and a production method capable of easily producing the adsorbent.SOLUTION: An adsorbent includes a chemical compound expressed by one of a general formula (1): ATiSiO.nHO (A denotes at least one kind selected from a group composed of Na, K and Li, and n denotes a number 0-8.), a general formula (2): ATiO.mHO (m denotes a number 0-10.) and a general formula (3): (AH)TiO.mHO (x denotes a number that satisfies 0.1≤x≤2). The A in at least one chemical compound from the chemical compounds contains Li.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an adsorbent capable of selectively and efficiently separating and recovering cesium or strontium in seawater, and a method for producing the adsorbent.

  Conventionally, coprecipitation treatment is known as a treatment technique for wastewater containing radioactive substances (see Patent Document 1 below). However, for radioactive cesium and radioactive strontium that are water-soluble, the coprecipitation treatment is not effective, and at present, adsorption removal by an inorganic adsorbent such as zeolite is performed (see Patent Document 2 below).

  However, when radioactive cesium and radioactive strontium flow into seawater, an increase in the sodium concentration of seawater components acts to suppress the ion exchange reaction between cesium and the adsorbent (see Non-Patent Document 1 below). The problem is known.

Silicotitanate is one of the inorganic adsorbents studied so far for the adsorptivity of cesium and / or strontium. Silicotitanates are known to have a plurality of compositions such as those having a Ti / Si ratio of 1: 1, 5:12, and 2: 1. In addition, the Ti / Si ratio is 4 : Silicotitanate is known to be present. Non-Patent Document 2 discloses that products 3B and 3C produced by hydrothermal treatment using an alkoxide Ti (OET) ₄ as a Ti source and colloidal silica as a Si source are three-dimensional from the X-ray diffraction pattern. The crystalline silicotitanate having this structure ideally has a composition represented by M ₄ Ti ₄ Si ₃ O ₁₆ (M is Na, K, etc.). It is reported that the crystalline silicotitanate having this structure is named Grace titanium silicate (GTS-1). Non-Patent Document 3 describes that a crystalline silicotitanate having a Ti / Si ratio of 4: 3 was produced by subjecting a mixed solution having a Ti / Si ratio of 0.32 to hydrothermal synthesis. ing. This document describes that the synthesized silicotitanate has strontium ion exchange ability.

Japanese Patent Laid-Open No. 62-266499 JP2013-57599A

JAEA-Research 2011-037 ZEOLITES, 1990, Vol 10, November / December Keiko Fujiwara, “Modification and evaluation of microporous crystals as heat pump adsorbents”, [online], [March 3, 2014 search], Internet <URL: http://kaken.nii.ac.jp/pdf /2011/seika/C19/15501/21560846seika.pdf>

  As described above, silicotitanate having a Ti / Si ratio of 4: 3 has been reported to have strontium exchange ability, but further improvement in adsorption performance of strontium and cesium is desired. Accordingly, an object of the present invention is to provide an adsorbent having high adsorption performance of cesium and / or strontium even in seawater, and an industrially advantageous production method of the adsorbent.

  As a result of intensive studies to solve the above problems, the present inventors have found that silicotitanate having a specific composition containing lithium and a specific titanate have high cesium and / or strontium adsorption performance from seawater. I found it.

That is, the present invention relates to general formula (1); A ₄ Ti ₄ Si ₃ O ₁₆ .nH ₂ O (wherein A represents at least one alkali metal selected from the group consisting of Na, K and Li, and n represents A silicotitanate represented by 0 to 8),
General formula (2); A ₄ Ti ₉ O ₂₀ · mH ₂ O (wherein A represents at least one alkali metal selected from the group consisting of Na, K and Li, and m represents a number of 0 to 10). ) And the general formula (3); (A _x H _(2-x) ) Ti ₂ O ₅ .mH ₂ O (wherein A is from Na, K and Li) At least one alkali metal selected from the group consisting of: x represents a number satisfying 0.1 ≦ x ≦ 2, and m represents a number from 0 to 10.
An adsorbent for cesium or strontium, comprising one or two or more compounds selected from the above, wherein A in at least one of the one or two or more compounds contains Li. Is.

The present invention also relates to a general formula (1); A ₄ Ti ₄ Si ₃ O ₁₆ .nH ₂ O (wherein A represents at least one alkali metal selected from the group consisting of Na, K and Li, n Represents a number of 0 to 8.) Silicotitanate represented by
General formula (2); A ₄ Ti ₉ O ₂₀ · mH ₂ O (wherein A represents at least one alkali metal selected from the group consisting of Na, K and Li, and m represents a number of 0 to 10). ) And the general formula (3); (A _x H _(2-x) ) Ti ₂ O ₅ .mH ₂ O (wherein A is from Na, K and Li) At least one alkali metal selected from the group consisting of: x represents a number satisfying 0.1 ≦ x ≦ 2, and m represents a number from 0 to 10.
A method for producing an adsorbent for cesium or strontium, comprising one or two or more compounds selected from the above, wherein A in at least one of the one or two or more compounds contains Li Because
A first step of obtaining a mixed gel by mixing a silicic acid source, an alkali metal compound, titanium tetrachloride, and water;
A second step of hydrothermal reaction of the mixed gel obtained in the first step,
As the alkali metal compound, at least one selected from a sodium compound and a potassium compound and a lithium compound are used, or a lithium compound is used. In the first step, the molar ratio of Ti and Si contained in the mixed gel is Ti / Si. The present invention provides a method for producing an adsorbent for cesium or strontium, wherein a silicic acid source and titanium tetrachloride are added so as to be 0.5 to 3.0.

  ADVANTAGE OF THE INVENTION According to this invention, the adsorbent excellent in the adsorption removal characteristic of cesium and / or strontium can be provided also in seawater, and this adsorbent can be manufactured by an industrially advantageous method.

FIG. 1 is an X-ray diffraction chart of the adsorbent obtained in Examples 1 and 2. FIG. 2 is an X-ray diffraction chart of the adsorbents obtained in Examples 3 to 5. FIG. 3 is an X-ray diffraction chart of the adsorbents obtained in Examples 6 and 7. FIG. 4 is an X-ray diffraction chart of the adsorbent obtained in Example 8. FIG. 5 is an X-ray diffraction chart of the adsorbent obtained in Comparative Example 1. FIG. 6 is an X-ray diffraction chart of the adsorbents obtained in Examples 9 and 10. FIG. 7 is an X-ray diffraction chart of the adsorbents obtained in Examples 11-13.

The adsorbent of the present invention has the general formula (1); A ₄ Ti ₄ Si ₃ O ₁₆ .nH ₂ O (wherein A represents at least one alkali metal selected from the group consisting of Na, K and Li, n represents a number of 0 to 8), and is represented by a silicotitanate (hereinafter also simply referred to as silicotitanate or the above-mentioned silicotitanate),
General formula (2); A ₄ Ti ₉ O ₂₀ · mH ₂ O (wherein A represents at least one alkali metal selected from the group consisting of Na, K and Li, and m represents a number of 0 to 10). And titanate (I) (hereinafter also simply referred to as titanate (I) or titanate (I)), and general formula (3); (A _x H _(2-x) ) Ti ₂ O ₅ .mH ₂ O (wherein A represents at least one alkali metal selected from the group consisting of Na, K and Li, x represents a number satisfying 0.1 ≦ x ≦ 2, and m represents 0 Is represented by a titanate (II), (hereinafter also simply referred to as titanate (II) or titanate (II)).
And at least one compound selected from the group consisting of The present invention is characterized in that lithium is contained in the silicotitanate, the titanate (I), or the titanate (II). Since the adsorbent of the present invention has this characteristic, it has excellent cesium (Cs) and / or strontium (Sr) adsorption removal performance.

Examples of the silicotitanate include Li ₄ Ti ₄ Si ₃ O ₁₆ .nH ₂ O, (Li _p Na _q K _(1-pq) ) ₄ Ti ₄ Si ₃ O ₁₆ .nH, assuming that A contains Li. ₂ O (wherein p and q are numbers such that p is more than 0 and less than 1, q is 0 or more and less than 1, and p + q is more than 0 and less than 1). , A does not contain Li, Na ₄ Ti ₄ Si ₃ O ₁₆ .nH ₂ O, (Na _s K _(1-s) ) ₄ Ti ₄ Si ₃ O ₁₆ .nH ₂ O (wherein s is And a compound represented by each formula of K ₄ Ti ₄ Si ₃ O ₁₆ .nH ₂ O. Any one of these may be used, or a mixture of two or more thereof may be used. Among these, when A contains a compound represented by (Li _p Na _q K _(1-pq) ), p and q may each take only one value, A mixture of p and / or q having a value of 2 or more may be used (the same applies to the following titanates (I) and (II)). Among these, when a compound represented by (Na _s K _(1-s) ) ₄ is contained, the compound may be one in which s takes only one value, and has a value of 2 or more. It may be a mixture of the same (the same applies to the following titanates (I) and (II)). In silicotitanate, n may take only one value, or n may take two or more values.

As the titanate (I), for example, assuming that A contains Li, Li ₄ Ti ₉ O ₂₀ .mH ₂ O, (Li _p Na _q K _(1-pq) ) ₄ Ti ₉ O ₂₀ .mH ₂ A compound represented by each formula of O (wherein p and q are numbers such that p is greater than 0 and less than 1, q is 0 or more and less than 1, and p + q is greater than 0 and 1 or less), illustrated as a contains no _{Li, Na 4 Ti 9 O 20} · mH 2 O, the number of _{(Na S K (1-S} )) is _{4 Ti 9 O 20 · mH 2} O (s less than 0 ultra 1 ) And a compound represented by each formula of K ₄ Ti ₉ O ₂₀ · mH ₂ O. Any one of these may be used, or a mixture of two or more thereof may be used. In the titanate (I), m may take only one value, or m may take two or more values.

As the titanate (II), for example, assuming that A contains Li, (Li _x H _(2-x) ) Ti ₂ O ₅ .mH ₂ O, ((Li _p Na _q K _(1-pq) ) _X H _(2-x) ) Ti ₂ O ₅ .mH ₂ O (wherein p and q are more than 0 and less than 1, q is 0 or more and less than 1, and p + q is more than 0 and less than 1) And (N _x H _(2-x) ) Ti ₂ O ₅ .mH ₂ O, ((Na _s K _{( 1-s)} ) _x H _(2-x) ) Ti ₂ O ₅ .mH ₂ O (wherein s is a number greater than 0 and less than 1), (K _x H _(2-x) ) Ti ₂ O ₅ · mH ₂ O, and the like. Any one of these may be used, or a mixture of two or more thereof may be used. In the titanate (II), m may take only one value, or m may take two or more values. As titanate (II), x is preferably 1 ≦ x ≦ 1.95. Moreover, what m is 1 <= m <= 5 is preferable.

  A used in the general formulas (1) to (3) and m used in the general formulas (2) and (3) may be the same or different between these different general formulas. The same applies to p, q, and s used in the explanation of the general formulas (1) to (3).

  The silicotitanate, titanate (I) and titanate (II) used in the present invention may each be crystalline, amorphous, crystalline or amorphous And a mixture thereof.

  It is preferable that the adsorbent of the present invention contains the above-mentioned silicotitanate from the viewpoint of improving the adsorption performance of Sr and Cs, particularly Cs. The inclusion of the titanate (I) and / or the titanate (II) is particularly preferable from the viewpoint of improving the Sr adsorption performance. For example, from the viewpoint of adsorbing Sr and Cs in a balanced manner, the adsorbent of the present invention contains the silicotitanate and the titanate (I) and / or the titanate (II). Is preferred.

  In addition, when the adsorbent of the present invention contains the silicotitanate, if the silicotitanate includes silicotitanate containing A and Na, and / or K, particularly K, the silicotitanate crystals in the adsorbent It may be possible to increase the performance of the adsorbent, particularly the adsorption performance of cesium.

  The adsorbent of the present invention preferably has a specific diffraction peak pattern by X-ray diffraction measurement.

  For example, the adsorbent of the present invention has at least 1 peak derived from the silicotitanate when X-ray diffraction measurement is performed with Cu-Kα as the X-ray source and a diffraction angle (2θ) in the range of 5 to 80 °. It is preferable from the viewpoint that the crystallinity of the silicotitanate is high and the adsorption performance of Cs is high. In particular, in the radiation source and the diffraction angle range, it is preferable that the highest intensity peak of the silicotitanate (hereinafter also referred to as a main peak) is observed in a diffraction angle (2θ) range of 10 to 13 °. . The peak observed in the range of 10 to 13 ° is derived from the silicotitanate having a crystal orientation of (0, 1, 0) and n of 5 to 7. In order to produce an adsorbent in which the main peak of silicotitanate is in the diffraction angle range, for example, an adsorbent is produced using a production method described later, and in that case, a silicic acid source, a lithium compound, a sodium compound, What is necessary is just to adjust material ratios, such as a potassium compound and titanium tetrachloride.

  If the main peak of the silicotitanate is observed in the range of diffraction angle (2θ) = 10-13 °, in addition to this, 27 ° -29 ° and / or 33.5 ° -35.5 ° (particularly 34 It is preferable that the silicotitanate peak is further observed in the range of [deg.] To 35 [deg.]. Moreover, it is preferable that these peaks have a height of 5% or more and 40% or less with respect to the height of the main peak of the silicotitanate described above.

  In the present invention, the peak height ratio is calculated based on a diffraction peak pattern obtained by performing baseline correction on a diffraction peak pattern obtained by actual X-ray diffraction measurement. This baseline correction is performed by the sonneveld-visser method. The peak height is obtained from the diffraction peak pattern as follows. First, a straight line is obtained by connecting two bottom points of one peak. Then, a perpendicular line is drawn from the peak apex to intersect with the straight line, and the distance between the obtained intersection and the peak apex is defined as the peak height.

  In the adsorbent of the present invention, at least one peak of the titanate (I) is observed when X-ray diffraction measurement is performed using the above-mentioned radiation source in a diffraction angle (2θ) range of 5 to 80 °. It is preferable from the viewpoint of improving the Sr adsorption performance of the adsorbent. From the same viewpoint, it is preferable that the main peak of the titanate (I) is observed at a diffraction angle (2θ) = 8 to 10 °. The peak observed at 8 to 10 ° is derived from the titanate (I) whose crystal orientation is (0, 1, 0) and m in the general formula (2) is 5 to 7. To do. Accordingly, such an adsorbent contains a large amount of a hydrate salt having m of 5 to 7 as the titanate (I). In order to produce an adsorbent in which the main peak of titanate (I) is in the above diffraction angle range, for example, an adsorbent is produced using a production method described later, and in that case, a silicate source, lithium What is necessary is just to adjust material ratios, such as a compound, a sodium compound, a potassium compound, and titanium tetrachloride.

  When the main peak of the titanate (I) is observed in the range of diffraction angle (2θ) = 8 to 10 °, in addition to this, in the range of 27 to 29 ° and / or 47 to 49 °, It is preferred that the titanate (I) peak is observed. Further, these peaks preferably have a height of 10% or more and 70% or less with respect to the height of the main peak of the titanate (I) described above.

In the adsorbent of the present invention, at least one peak of the titanate (II) is observed when X-ray diffraction measurement is performed with a diffraction angle (2θ) of 5 to 80 ° using the above-mentioned radiation source. It is preferable from the viewpoint of improving the Sr adsorption performance. In particular, the main peak of the titanate (II) is preferably observed at a diffraction angle (2θ) of 9 to 11 °. The peak observed at 9 to 11 ° is derived from the titanate (II) represented by (Li _x H _(2-x) ) Ti ₂ O ₅ .mH ₂ O. Therefore, such an adsorbent contains a large amount of the compound represented by (Li _x H _(2-x) ) Ti ₂ O ₅ .mH ₂ O as the titanate (II). In order to produce an adsorbent having a main peak of titanate (II) in the above diffraction angle range, for example, an adsorbent is produced using a production method described later, and in that case, a silicate source, lithium What is necessary is just to adjust material ratios, such as a compound, a sodium compound, a potassium compound, and titanium tetrachloride.

When the main peak of the titanate (II) is observed in the range of diffraction angle (2θ) = 9 to 11 °, in addition to this, 27 to 29.5 ° and / or 36.0 to 38.0 It is preferable that a peak of the titanate (II) ((Li _x H _(2-x) ) Ti ₂ O ₅ .mH ₂ O) is further observed in the range of °. Moreover, it is preferable that these peaks have a height of 20% or more and 150% or less with respect to the height of the main peak of the titanate (II) described above.

  In the adsorbent of the present invention, for example, when X-ray diffraction measurement is performed in the range of diffraction angle (2θ) of 5 to 80 ° using the above-mentioned radiation source, one or more peaks of the silicotitanate are observed and the titanate One or more peaks of (I) are preferably observed from the viewpoint of adsorbing both Cs and Sr in a balanced manner. In particular, the main peak of silicotitanate is observed in the range of diffraction angle (2θ) = 10 to 13 °, and the main peak of titanate (I) in the range of diffraction angle (2θ) = 8 to 10 °. Is preferably observed.

  In this case, the main peak of the silicotitanate from the viewpoint of improving the balance of the adsorption performance of Sr and Cs when X-ray diffraction measurement is performed in the range of the radiation source and the diffraction angle (2θ) of 5 to 80 °. The ratio of the height of the main peak of the titanate (I) to the height is preferably 15% to 65%, more preferably 20% to 60%, and more preferably 25% to 55%. % Or less is more preferable. In order to produce an adsorbent having a peak height ratio within the above range, for example, an adsorbent is produced by a production method described later, and at that time, a silicic acid source, a lithium compound, a sodium compound, a potassium compound, tetrachloride. What is necessary is just to adjust material ratios, such as titanium.

As described above, the adsorbent of the present invention has a peak of silicotitanate of 1 when the X-ray diffraction measurement is performed using Cu-Kα as the X-ray source and the diffraction angle (2θ) is in the range of 5 to 80 °. It is preferable that one or more peaks of the titanate (I) are observed while being observed as described above, but may have a different peak pattern.
For example, when X-ray diffraction measurement is performed using Cu—Kα as an X-ray source in a diffraction angle (2θ) range of 5 to 80 °, one or more peaks of the silicotitanate are observed and the titanate ( It is also preferable that at least one peak of II) is observed from the viewpoint of adsorbing both Cs and Sr in a balanced manner. In this case, the main peak of the silicotitanate is observed in the range of diffraction angle (2θ) = 10-13 °. In addition, it is more preferable that the main peak of the titanate (II) is observed in the range of diffraction angle (2θ) = 9 to 11 °.

  If X-ray diffraction measurement is performed with the source and the diffraction angle (2θ) in the range of 5 to 80 °, the main peak of the silicotitanate is observed in the range of the diffraction angle (2θ) = 10 to 13 ° and When the main peak of the titanate (II) is observed in the range of diffraction angle (2θ) = 9 to 11 °, the main body of the silicotitanate is used from the viewpoint of improving the balance of adsorption performance between Sr and Cs. The ratio of the main peak height of the titanate (II) to the peak height is preferably 10% to 90%, more preferably 20% to 80%, and more preferably 30% to 70%. % Or less is more preferable.

  Moreover, when X-ray diffraction measurement was performed using Cu—Kα as a radiation source and a diffraction angle (2θ) in the range of 5 to 80 °, peaks of titanate (I) and titanate (II) were observed. It is also preferable from the viewpoint of Sr adsorption performance. For example, the main peak of the titanate (I) is observed in the range of diffraction angle (2θ) = 8 to 10 °, and the titanate (II) is in the range of diffraction angle (2θ) = 9 to 11 °. It is preferred that a main peak is observed.

  If the X-ray diffraction measurement is performed in the range of the radiation source and the diffraction angle (2θ) of 5 to 80 °, the main peak of the titanate (I) is in the range of the diffraction angle (2θ) = 8 to 10 °. When the main peak of the titanate (II) is observed in the range of diffraction angle (2θ) = 9 to 11 °, the two peaks overlap and become a broad peak slightly, The top one peak.

  For example, the main peak of titanate (I) is observed in the range of diffraction angle (2θ) = 8 to 10 °, and the main salt of titanate (II) in the range of diffraction angle (2θ) = 9 to 11 °. When the peak overlaps with the main peak of titanate (I) and cannot be clearly observed, it corresponds to the main peak height of titanate (I) observed in the range of 2θ = 8 to 10 °. The abundance ratio of both may be confirmed by the ratio of the peak heights of the titanate (II) observed in the range of 2θ = 27 to 29.5. This ratio is preferably 5% or more and 300% or less, preferably 10% or more and 300% or less, from the viewpoint of improving the Sr adsorption performance and confirming that the target titanate is synthesized. More preferably, it is 10% or more and 250% or less.

  As described above, the preferable peak ratio between the components of the general formulas (1) to (3) has been described. However, as described above, the components of the general formulas (1) to (3) are not limited to crystalline ones. . For example, the main peak of the titanate (I) is observed in the range of 8 to 10 °, or the main peak of the titanate (II) is observed in the range of 9 to 11 ° and is amorphous. The adsorbent containing silicotitanate in this state is also preferable because it has a high Sr adsorption performance and a Cs adsorption performance of a certain level or higher.

  In order to obtain these adsorbents, for example, the adsorbent of the present invention is produced by the production method described later, and at that time, a silicic acid source, a lithium compound, a sodium compound, a potassium compound, titanium tetrachloride, etc. The material ratio may be adjusted, or the components represented by the general formulas (1) to (3) may be added to the product of the production method.

The adsorbent of the present invention may contain silicotitanate having a composition other than A ₄ Ti ₄ Si ₃ O ₁₆ .nH ₂ O. However, when the adsorbent of the present invention is measured by X-ray diffraction at a diffraction angle (2θ) of 5 to 80 °, as a silicotitanate, at least a crystalline silicotitanate having a molar ratio of Ti and Si of 1: 1. It is preferable that the peak of the crystalline silicotitanate having a molar ratio of Ti and Si of 5:12 is not observed. In particular, when the adsorbent of the present invention is measured by X-ray diffraction at a diffraction angle (2θ) of 5 to 80 °, a peak of only A ₄ Ti ₄ Si ₃ O ₁₆ .nH ₂ O is observed as a peak of silicotitanate. It is preferred that In addition, when the adsorbent of the present invention is measured by X-ray diffraction, it is preferable that a peak of 2θ = 25 ° which is a peak of titanium oxide is not observed.

The adsorbent of the present invention may contain a titanate other than the titanate (I) and titanate (II), for example, Na ₂ Ti ₃ O _7. Of the titanate (I) and / or the titanate (II) as titanate when X-ray diffraction measurement is performed with the above-mentioned radiation source within a diffraction angle (2θ) of 5 to 80 °. Preferably only peaks are observed.

When the X-ray diffraction measurement of the adsorbent of the present invention was performed at a diffraction angle (2θ) of 5 to 80 ° with the above-mentioned radiation source, the titanate (II) ) ((Li _x H _(2-x) ) Ti ₂ O ₅ .mH ₂ O) main peak is observed, or diffraction angle (2θ) = 27 to 29.5 ° or 36.0 to 38 When the titanate (II) peak is observed in a range of 0.0 °, the molar ratio of (Na + K + Li): Li obtained by, for example, composition analysis of the adsorbent of the present invention is 1: 0. Higher than 25 is preferable from the viewpoint of easy production of the adsorbent of the present invention containing the titanate (II). On the other hand, when the main peak of titanate (I) is observed in the range of diffraction angle (2θ) = 8 to 10 °, the molar ratio of (Na + K + Li): Li obtained by composition analysis of the adsorbent is It is preferable from the viewpoint of easy production of the adsorbent of the present invention containing the titanate (I) that is 1: 0.05 or more and 0.7 or less, particularly about 1: 0.05 or more and 0.45 or less. . When the main peak of the silicotitanate is observed in the range of diffraction angle (2θ) = 10-13 °, the molar ratio of (Na + K + Li): Li is 1: 0.01 or more and 0.08 or less, particularly 1: 0. It is preferable that it is as low as 0.01 or more and 0.05 or less from the viewpoint of easy production of the adsorbent of the present invention containing the silicotitanate. This is because the titanate (II) is stable when the Li content is high, whereas the crystalline silicotitanate and the crystalline titanate (I) are both stable when the Li content is low. This is because it can be considered. The molar ratio (Na + K + Li): Li is obtained by dissolving an adsorbent in hydrofluoric acid, then diluting the solution using ion-exchanged water as a dilution medium, and subjecting the resulting diluted solution to ICP emission spectrometry. It can be determined by analysis. ICPS-8100CL manufactured by Shimadzu Corporation can be used as an analyzer for ICP emission spectroscopy. When the adsorbent contains titanate (II) in particular, the molar ratio (Na + K + Li): Li determined by the above method is the lithium compound in the alkali metal compound used for the production of the adsorbent. Compared to the proportion, the proportion of lithium tends to increase. This is because titanate (II) in which A is Li is preferentially produced over titanate (II) in which A is Na or K.

The amount ratio of Na and K in the case of using Na and / or K is not particularly limited. For example, it is preferable that A contains K from the viewpoint of improving the crystal performance of silicotitanate. The molar ratio of (Na + K + Li): K may be appropriately selected from Ce and Sr in order to obtain the desired adsorption performance. For example, considering the ease of production of the adsorbent and the cost of the raw material alkali. For example, it is preferably 1: 0.1 or more and 0.7 or less, and particularly preferably 1: 0.2 or more and 0.6 or less. As described above, in the production method of the present invention, when Li / A ^* is low, an adsorbent containing crystalline silicotitanate is obtained, but the use of a potassium compound increases the crystallinity of the resulting silicotitanate. Has an effect. For this reason, in the production method of the present invention, the use of a potassium compound has the effect of slightly relaxing the Li / A ^* conditions for obtaining an adsorbent containing crystalline silicotitanate when no potassium compound is used. .

  In the adsorbent of the present invention, the molar ratio of Ti: Si obtained by the composition analysis is preferably 1: 0.30 to 0.55 from the viewpoint of facilitating adsorption of both Sr and Cs. From this viewpoint, the molar ratio of Ti: Si is more preferably 1: 0.34 to 0.50, and particularly preferably 1: 0.36 to 0.48. However, for example, as described later, when the adsorbent of the present invention is produced without using a silicic acid source, the molar ratio is not limited.

  Examples of the form of the adsorbent of the present invention include powders, granules, and moldings other than granules (spherical or cylindrical), and the like is preferable. The powdery adsorbent can be obtained, for example, by drying or drying and pulverizing a reaction product obtained in the second step of the production method described later. Moreover, a granular adsorbent can be obtained by granulating a powder adsorbent by the granulation process mentioned later.

  When the adsorbent of the present invention is a granule, it preferably has a particle size of 200 μm or more and 1000 μm or less. Since the adsorbent of the present invention composed of granules of this particle size does not have particles finer than 200 μm or is extremely small even if present, the adsorbent of the present invention is packed in an adsorption tower and passed through. In this case, it is possible to prevent the problem that particles are clogged in the adsorption tower. Moreover, when the particle size is 1000 μm or less, the adsorption performance of the adsorbent is easily improved.

  Specifically, when the adsorbent of the present invention is a granular material, when the sieve according to JIS Z8801 standard has a sieve having an opening of 212 μm and the sieve having an aperture of 1 mm, the adsorbent of the present invention It is preferable that 98% by mass or more, particularly 99% by mass or more pass through a sieve having an opening of 1 mm, and 98% by mass or more, particularly 99% by mass or more should not pass through a sieve having an opening of 212 μm. In particular, the adsorbent of the present invention is preferably composed of a granular material having a particle size of 300 μm or more and 600 μm or less. Specifically, when a sieve having an opening of 300 μm according to JIS Z8801 standard and a sieve having an opening of 600 μm are used, 98 mass% or more, particularly 99 mass% or more of the adsorbent of the present invention is the above-mentioned 600 μm. It is preferable that 98% by mass or more, particularly 99% by mass or more, does not pass through the 300 μm sieve.

  The adsorbent of the present invention described above can be preferably manufactured by the method for manufacturing an adsorbent of the present invention described below.

  The first step in the method for producing an adsorbent of the present invention is a step of producing a mixed gel by mixing a silicic acid source, an alkali metal compound, titanium tetrachloride, and water. As the alkali metal compound, at least one selected from a sodium compound and a potassium compound and a lithium compound are used, or a lithium compound is used.

  Examples of the silicic acid source used in the first step include sodium silicate. Moreover, the active silicic acid obtained by carrying out cation exchange of the alkali silicate (namely, alkali metal salt of silicic acid) is also mentioned. Examples of the silicate source include lithium silicate and potassium silicate.

  The activated silicic acid is obtained by cation exchange by bringing an aqueous alkali silicate solution into contact with, for example, a cation exchange resin. As a raw material for the alkali silicate aqueous solution, a sodium silicate aqueous solution usually called water glass (water glass No. 1 to No. 4 etc.) is preferably used. This is relatively inexpensive and can be easily obtained. For semiconductor applications that dislike Na ions, an aqueous potassium silicate solution is suitable as a raw material. There is also a method of preparing an alkali silicate aqueous solution by dissolving solid alkali silicate in water. Alkali metasilicates are produced through a crystallization process, so some of them have few impurities. The aqueous alkali silicate solution is diluted with water as necessary.

  The cation exchange resin used when preparing the active silicic acid can be appropriately selected from known ones and is not particularly limited. In the contacting step between the alkali silicate aqueous solution and the cation exchange resin, for example, the alkali silicate aqueous solution is diluted with water so that the silica has a concentration of 3% by mass or more and 10% by mass or less. Contact with a strong acidic or weakly acidic cation exchange resin to dealkalize. Further, if necessary, it can be deanioned by contacting with an OH type strongly basic anion exchange resin. By this step, an active silicic acid aqueous solution is prepared. Regarding the details of the contact conditions between the aqueous alkali silicate solution and the cation exchange resin, various proposals have already been made, and any known contact conditions can be adopted in the present invention.

For example, while highly dispersed SiO ₂ powder is used as a silicon source in Non-Patent Document 3, it is possible to use sodium silicate or activated silicic acid as a silicic acid source in the production method of the present invention. This has the advantage that the manufacturing cost can be reduced. Moreover, when using lithium silicate as a silicic acid source, it has the advantage which can prevent the fall of a slurry density | concentration by using it as high concentration Li salt aqueous solution.

Examples of the sodium compound used in the first step include sodium hydroxide and sodium carbonate. Among these sodium compounds, when sodium carbonate is used, carbon dioxide gas is generated. Therefore, it is preferable to use sodium hydroxide that does not generate such gas from the viewpoint of smoothly promoting the neutralization reaction.
Examples of the potassium compound used in the first step include potassium hydroxide and potassium carbonate, and potassium hydroxide is preferred for the same reason as the sodium compound.
Examples of the lithium compound used in the first step include lithium hydroxide and lithium carbonate, and lithium hydroxide is preferable for the same reason as the sodium compound.

When a sodium compound or a potassium compound is used in the first step, the ratio of the number of moles of lithium compound to the total number of moles of sodium compound, potassium compound and lithium compound (Li / A ^* ) is important. For example, when Li / A ^* is sufficiently small, such as about 0.1 or less, particularly about 0.05 or less, an adsorbent containing crystalline silicotitanate (CST) can be obtained. When Li / A ^* becomes a little larger than that, an adsorbent containing the titanate (I) together with the crystalline silicotitanate (CST) is obtained. Further, when Li / A ^* increases, an adsorbent containing the titanate (I) but not crystalline silicotitanate (CST) is obtained. When Li / A ^* further increases, an adsorbent containing the titanate (II) can be obtained together with the titanate (I) or instead of the titanate (I). Li / A ^* is particularly preferably 0.01 or more and 0.05 or less when an adsorbent containing crystalline silicotitanate, which is a compound having high Cs adsorption performance, is to be obtained. Li / A ^* is preferably 0.01 or more and 0.5 or less in the case of obtaining an adsorbent containing titanate (I) which is a compound having high Sr adsorption performance. More preferably, it is 02 or more and 0.3 or less. In addition, Li / A ^* is preferably 0.01 or more and 0.05 or less, and preferably 0.02 or more and 0.0 or less, in order to obtain an adsorbent containing titanate (I) together with crystalline silicotitanate. More preferably, it is 05 or less. Furthermore, Li / A ^* is preferably 0.1 or more and 1 or less, when obtaining an adsorbent containing titanate (II), which is a compound having high Sr adsorption performance, It is preferable that it is 0.5 or less. In the production method of the present invention, when Li / A ^* is as low as 0.01 or more and 0.05 or less, the adsorbent of the present invention can be combined with crystalline silicotitanate and titanic acid (I), Thereby, the adsorbent can have a high adsorption performance of Cs and Sr. However, even when Li / A ^* is as high as 0.05 or more, particularly 0.1 or more, an adsorbent having a certain degree of Cs adsorption performance and high Sr adsorption performance can be obtained. When the ratio of the number of moles of the lithium compound is so high, the formation of titanate (II) is promoted to increase the adsorption performance of Sr and the amorphous of silicotitanate is produced, which increases the adsorption performance of Cs. Are thinking.

The amount ratio of the sodium compound and / or potassium compound in the case of using the sodium compound and / or potassium compound is not particularly limited, but for example, the use of a potassium compound is preferable from the viewpoint of enhancing the crystal performance of silicotitanate. In the case of using a potassium compound, the ratio of the number of moles of potassium compound (K / A ^* ) to the total number of moles of sodium compound, potassium compound and lithium compound takes into account, for example, the ease of production of the adsorbent and the cost of the raw material alkali. For example, it is preferably 0.001 or more and 1 or less, particularly 0.01 or more and 0.9 or less.

The numerical ranges (Li / A ^* ) and (K / A ^* ) are the amounts of the sodium compound, the potassium compound or the lithium compound when the silicic acid source is a sodium compound, a potassium compound or a lithium compound. This is the range when the amount of silicic acid source is included.

  In the adsorbent production method of the present invention, titanium tetrachloride is used as a titanium source. When other titanium compounds such as titanium oxide are used as the titanium source, unreacted titanium oxide remains, or silicotitanate other than silicotitanate having a molar ratio of Ti: Si of 4: 3 tends to be generated. Therefore, in the present invention, titanium tetrachloride is used as the titanium source.

  The addition amount of the silicic acid source and titanium tetrachloride may be set to an amount in which Ti / Si, which is the molar ratio of Ti derived from titanium tetrachloride and Si derived from the silicic acid source in the mixed gel, becomes a specific ratio. It is one of the characteristics of the manufacturing method of the adsorption agent of invention. For example, in Non-Patent Document 3, titanium tetrachloride is used as the titanium source, but the silicate source and titanium tetrachloride are added to the mixed solution in such an amount that the Ti / Si ratio is 0.32. In contrast, in the present invention, the silicic acid source and titanium tetrachloride are added in such an amount that the Ti / Si ratio is 0.5 or more and 3.0 or less. By setting the Ti / Si ratio in the mixed gel in the above molar range, the adsorption performance of Cs of the adsorbent is easily improved. From this viewpoint, the Ti / Si ratio in the mixed gel is preferably 1.0 or more and 3.0 or less, more preferably 1.5 or more and 2.5 or less, and 1.8 or more and 2.2 or less. More preferably, it is as follows.

  In the mixed gel of the present invention, the Ti / Si ratio is within the above range, which means that the obtained adsorbent easily contains titanate (I) or titanate (II) as a by-product together with silicotitanate. This is also preferable in that the adsorbent of the present invention described above can be suitably produced. In general, when a specific compound such as silicotitanate is usually used as an adsorbent, it is common to adopt a composition that does not contain by-products. Thus, one preferred embodiment of the production method of the present invention is as described above. Surprisingly, the adsorption performance of cesium and strontium is improved by adopting a relatively high Ti / Si ratio and generating by-products.

Further, the total amount of the SiO ₂ equivalent silicic acid source concentration and the TiO ₂ equivalent titanium tetrachloride concentration in the mixed gel is 2.0% by mass or more and 40% by mass or less, and A ′ ₂ O and SiO in the mixed gel it is desirable that the molar ratio of ₂ is added to silicic acid source and titanium tetrachloride so that _{a '2 O / SiO 2 =} 0.5 to 3.0. Here, A ′ represents Li, Na and K. By adjusting the addition amount of the silicate source and titanium tetrachloride within the above range, the Cs adsorption performance of the adsorbent obtained can be sufficiently increased, and the molar ratio of Ti and Si is 1: 1. It can prevent effectively that a product produces | generates.
These ranges are also preferable from the viewpoint of by-producing the titanate (I) or (II).

  The titanium tetrachloride used in the first step can be used without particular limitation as long as it is industrially available.

  In the first step, the silicic acid source, sodium compound, potassium compound, lithium compound and titanium tetrachloride can be added to the reaction system in the form of an aqueous solution, respectively. In some cases, it can be added in the form of a solid. Further, in the first step, if necessary, the concentration of the mixed gel can be adjusted using pure water for the obtained mixed gel.

  In the first step, the silicic acid source, sodium compound, potassium compound, lithium compound and titanium tetrachloride can be added in various addition orders. For example, (1) A mixed gel is obtained by adding titanium tetrachloride to a mixture of a silicic acid source, an alkali metal compound (at least one selected from a sodium compound and a potassium compound, and a lithium compound or lithium compound) and water. (This addition order may be simply referred to as “execution of (1)” hereinafter.) The implementation of (1) is preferable in that the generation of chlorine from titanium tetrachloride is suppressed.

  As another order of addition in the first step, (2) an aqueous solution of activated silicic acid (hereinafter sometimes simply referred to as “activated silicic acid”) obtained by cation exchange of alkali silicate, titanium tetrachloride and water It is also possible to adopt an embodiment in which an alkali metal compound is added to the mixture. Even when this order of addition is adopted, a mixed gel can be obtained in the same manner as in the execution of (1) (this addition order may be simply referred to as “the execution of (2)” hereinafter). Titanium tetrachloride can be added in the form of an aqueous solution or solid form. Similarly, the alkali metal compound can also be added in the form of an aqueous solution or in the form of a solid.

(1) and in the practice of (2), sodium compounds, potassium compounds and lithium compounds, sodium in the mixed gel, the total concentration of potassium and lithium Na ₂ O 15% by mass to 0.5% by mass in terms of the following, In particular, it is preferable to add so that it may become 0.7 mass% or more and 13 mass% or less. The total Na ₂ O equivalent mass of sodium, potassium and lithium in the mixed gel and the Na ₂ O equivalent concentration of sodium, potassium and lithium in the mixed gel (hereinafter referred to as “total concentration of sodium, potassium and lithium (first When sodium and potassium compounds are not used in the process, the lithium concentration) ”is calculated by the following formula.
Total Na ₂ O equivalent mass (g) of sodium, potassium and lithium in the mixed gel = total number of sodium ions, potassium ions and lithium ions derived from silicic acid source + sodium ions derived from sodium compounds such as sodium hydroxide Mol number of potassium ion derived from potassium compound such as potassium hydroxide mol number of lithium ion derived from lithium compound such as lithium hydroxide−mol number of chloride ion derived from titanium tetrachloride) × 0.5 × Na ₂ O molecular weight Concentration (mass%) in terms of Na ₂ O of the total of sodium, potassium and lithium in the mixed gel =
Total Na ₂ O equivalent mass of sodium, potassium and lithium in the mixed gel / (water content in the mixed gel + total Na ₂ O equivalent mass of sodium, potassium and lithium in the mixed gel) × 100

By combining the selection of the silicic acid source and the adjustment of the total concentration of sodium, potassium and lithium in the mixed gel, generation of silicotitanate other than silicotitanate having a molar ratio of Ti: Si of 4: 3 can be suppressed. . When sodium silicate is used as the silicic acid source, the production of silicotitanate having a molar ratio of Ti: Si of 5:12 is effectively suppressed by making it 2.0% by mass or more in terms of Na ₂ O. On the other hand, when the total concentration of sodium, potassium and lithium in the mixed gel is 4.5% by mass or less in terms of Na ₂ O, generation of silicotitanate having a molar ratio of Ti: Si of 1: 1 is possible. Can be effectively suppressed. When activated silicic acid obtained by cation exchange of alkali silicate is used as the silicic acid source, the molar ratio of Ti: Si is 5:12 by setting it to 1% by mass or more in terms of Na ₂ O. The production of silicotitanate can be effectively suppressed. On the other hand, the total concentration of sodium, potassium and lithium in the mixed gel is set to 6% by mass or less in terms of Na ₂ O, so that the molar ratio of Ti: Si However, the production of 1: 1 silicotitanate can be effectively suppressed.

When sodium silicate is used as the silicate source, the sodium component in the sodium silicate simultaneously becomes the sodium source in the mixed gel. Therefore, the “Na ₂ O equivalent mass (g) of sodium in the mixed gel” referred to here is counted as the sum of all sodium components in the mixed gel.

  In the implementation of (1) and (2), it is desirable to add titanium tetrachloride stepwise or continuously as an aqueous titanium tetrachloride solution over a certain period of time in order to obtain a uniform gel. Therefore, a metering pump (such as a peristaltic pump) can be suitably used for adding titanium tetrachloride.

  In order to obtain a uniform product, the mixed gel obtained in the first step may be aged before performing a hydrothermal reaction which is a second step described later. The aging time is 0.5 hour or more and 2 hours or less, and the aging temperature is 30 ° C. or more and 100 ° C. or less. The aging step may be performed, for example, in a stationary state, or may be performed in a stirring state using a line mixer or the like.

  In the present invention, the mixed gel obtained in the first step is subjected to a hydrothermal reaction in the second step, and the lithium-containing compound represented by any one of the general formulas (1) to (4) An adsorbent containing compound is obtained. The hydrothermal reaction is not limited as long as the lithium-containing compound represented by any one of the general formulas (1) to (4) can be synthesized. Usually, it is preferably 120 ° C. or higher and 300 ° C. or lower, more preferably 120 ° C. or higher and 200 ° C. or lower, more preferably 140 ° C. or higher and 180 ° C. or lower, preferably 6 hours or longer and 120 hours or shorter, more preferably 12 ° C. in an autoclave. The reaction is carried out under pressure for a period of time not less than 120 hours. The reaction time can be selected according to the scale of the synthesizer.

  According to the above production method of the present invention, the adsorbent of the present invention, particularly the adsorbent of the present invention containing the silicotitanate can be efficiently produced. On the other hand, the adsorbent of the present invention which does not contain the silicotitanate, and in particular does not contain silicic acid-containing components such as silicotitanate, may be modified from the production method described below.

Specifically, when producing the adsorbent of the present invention containing no silicotitanate, the first step is performed by mixing titanium tetrachloride and the first alkali metal hydroxide to obtain Ti (OH) ₄ . What is necessary is just to modify | change so that it may produce | generate and then the produced | generated Ti (OH) ₄ and 2nd alkali metal hydroxide may be mixed.
As the first and second alkali metal hydroxides used in the first step, at least one selected from sodium hydroxide, potassium hydroxide and lithium hydroxide is used, and the first and / or second alkali metal is used. What contains lithium hydroxide as a hydroxide can be used.
In the first step, the second alkali metal hydroxide has an A ′ / Ti molar ratio (A ′ is Na, K) with respect to Ti (OH) ₄ produced by the addition of the first alkali metal hydroxide. And Li) are preferably used in a range of 1.0 to 5.0.

In order to mix the titanium tetrachloride and the first alkali metal hydroxide, for example, a titanium tetrachloride aqueous solution and a first alkali metal hydroxide aqueous solution may be mixed. In this case, the mixing method is particularly limited. There is no.
For example, the aqueous solution of the first alkali metal hydroxide can be added all at once or sequentially into the titanium tetrachloride aqueous solution. Conversely, an aqueous titanium tetrachloride solution can be added all at once or sequentially into the aqueous solution of the first alkali metal hydroxide. Furthermore, the titanium tetrachloride aqueous solution and the first alkali metal hydroxide aqueous solution can be added simultaneously or sequentially.

  In the mixing of the aqueous solution of titanium tetrachloride and the first alkali metal hydroxide, the molar ratio A ′ / Ti between the total sum of alkali metals and titanium is preferably 4.15 or more and 4.40 or less, more preferably 4 .25 or more and 4.30 or less.

  Moreover, it is preferable that the density | concentration of the titanium in the liquid mixture obtained by mixing a titanium tetrachloride aqueous solution and the aqueous solution of a 1st alkali metal hydroxide is 2 mass% or more and 4 mass% or less. By setting the concentration of titanium to 2% by mass or more, it is possible to effectively prevent the liquid from changing to a paste when an alkali metal hydroxide is added in the second step described later. Moreover, it can prevent effectively that a hard lump is not produced | generated in the 3rd process mentioned later by setting it as 4 mass% or less.

Mixing of the aqueous solution of titanium tetrachloride and the aqueous solution of the first alkali metal hydroxide is performed until there is no unreacted titanium tetrachloride in the mixed solution. The mixing of the titanium tetrachloride aqueous solution and the first alkali metal hydroxide aqueous solution produced Ti (OH) ₄ which is a water-insoluble compound of titanium in the liquid. It can be confirmed by mixing the product and forming a white precipitate. The absence of unreacted titanium tetrachloride in the mixed solution can be confirmed, for example, by measuring the pH of the mixed slurry. Specifically, since the lower limit pH at which Ti (OH) ₄ is generated is approximately 2.0, the presence or absence of unreacted titanium tetrachloride in the mixed solution can be determined using this pH value as an index. Since the solubility product K _sp of Ti (OH) ₄ is known to be an extremely small value of 8 × 10 ⁻⁵⁴ (25 ° C.), unreacted titanium tetrachloride is separated from the above pH value. It can be said that it no longer exists in the liquid.

Next, the liquid containing Ti (OH) ₄ obtained by the above mixing and the second aqueous solution of alkali metal hydroxide are mixed. The second alkali metal hydroxide may be the same as or different from the first alkali metal hydroxide. The second alkali metal hydroxide is preferably the same type as the first alkali metal hydroxide from the viewpoint that the production process is not complicated.

Against Ti (OH) Ti (OH) 4 as the mixing amount of the second alkali metal hydroxide for ₄ at this stage, a range of 1.0 to 5.0 expressed in terms of mole ratio A '/ Ti It is preferable to add a 2nd alkali metal hydroxide so that it may become. When the molar ratio A ′ / Ti is less than 1.0, it is difficult to obtain the target titanate. On the other hand, when the molar ratio A ′ / Ti exceeds 5.0, by-products are easily produced as a by-product. From these viewpoints, the molar ratio A ′ / Ti is more preferably 1.0 or more and 5.0 or less, and further preferably 1.0 or more and 3.0 or less.

As described above, as the first and second alkali metal hydroxides, at least one selected from sodium hydroxide, potassium hydroxide and lithium hydroxide is used, and the first and / or second alkalis are used. The metal hydroxide contains lithium hydroxide. The value of A ′ in the molar ratio A ′ / Ti is the sum of sodium hydroxide, potassium hydroxide and lithium hydroxide constituting the first or second alkali metal hydroxide. For example, when it is going to produce | generate said titanate (II) by this manufacturing method, the mole number of lithium hydroxide with respect to the total mole number of the alkali metal hydroxide which combined the 1st and 2nd alkali metal hydroxide. The ratio (Li / A ^** ) is preferably 5 or more and 100 or less, and more preferably 10 or more and 100 or less.

When mixing of the liquid containing Ti (OH) ₄ and the second aqueous solution of alkali metal hydroxide is completed, the mixed liquid is preferably subjected to an aging step before the second step. The aging can be performed, for example, in a temperature range of 30 ° C. or more and 100 ° C. or less over a period of 0.5 hours to 2 hours. A more uniform product can be obtained by aging. The aging may be performed, for example, in a stationary state or in a stirring state using a line mixer or the like.

Next, the second step is performed. About a 2nd process, it is as above-mentioned except using the liquid mixture obtained by mixing the liquid containing Ti (OH) ₄ and the aqueous solution of a 2nd alkali metal hydroxide instead of a mixed gel.

  The water-containing adsorbent obtained in the second step of the production method can be dried, and the obtained dried product can be crushed or pulverized as necessary to form a powder (including granules). Further, the adsorbent in a water-containing state is extruded from an aperture member in which a plurality of apertures are formed to obtain a rod-shaped molded body, and the obtained rod-shaped molded body may be dried to form a column or dried. The rod-shaped molded body may be formed into a spherical shape, or may be pulverized or pulverized into particles. In the latter case, that is, when extrusion is performed before drying, the yield of the adsorbent recovered by the classification method described later can be increased. Here, pulverization refers to an operation of loosening particles that are gathered into a lump, and pulverization refers to an operation of applying mechanical force to the loosened solid particles to make them finer.

  Examples of the shape of the hole formed in the opening member include a circle, a triangle, a polygon, and a ring shape. The true circle equivalent diameter of the opening is preferably 0.1 mm or more and 10 mm or less, and more preferably 0.3 mm or more and 5 mm or less. The true circle equivalent diameter here is a diameter of a circle calculated from the area when the area of one hole is a circle area. The drying temperature after extrusion molding can be, for example, 50 ° C. or more and 200 ° C. or less. The drying time can be 1 hour or more and 120 hours or less.

  The dried rod-shaped molded body can be used as an adsorbent as it is, or can be used after lightly loosening. Moreover, you may grind | pulverize and use the rod-shaped molded object after drying. The powdered adsorbents obtained by these various methods are preferably used after further classification from the viewpoint of increasing the adsorption efficiency of cesium and / or strontium. For classification, it is preferable to use, for example, a sieve having a nominal opening defined in JISZ8801-1.

  The adsorbent obtained by each of the above production methods is excellent in the adsorption and removal characteristics of cesium and / or strontium. Utilizing this property, the adsorbent can be molded according to a conventional method if necessary, and the resulting molded article can be suitably used as an adsorbent for cesium and / or strontium.

  As the molding process, for example, a powdery adsorbent or a powdery adsorbent containing the same is granulated, or a powdered adsorbent is slurried and a hardener such as calcium chloride is used. A method of encapsulating the adsorbent by dripping in the liquid containing the method, a method of applying and adsorbing adsorbent powder onto the surface of the resin core, the surface of the sheet-like substrate formed of natural fibers or synthetic fibers, and / or Examples thereof include a method in which a powdery adsorbent or a powdery adsorbent containing the adsorbent is adhered and fixed to form a sheet. Examples of the granulation method include known methods such as stirring and mixing granulation, rolling granulation, extrusion granulation, crushing granulation, fluidized bed granulation, spray drying granulation (spray drying), and compression granulation. A grain etc. can be mentioned. In the granulation process, a binder and a solvent may be added and mixed as necessary. As the binder, known ones such as polyvinyl alcohol, polyethylene oxide, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, hydroxyethylmethylcellulose, carboxymethylcellulose, hydroxypropylmethylcellulose, methylcellulose, ethylcellulose, starch, cornstarch, molasses, lactose, gelatin , Dextrin, gum arabic, alginic acid, polyacrylic acid, glycerin, polyethylene glycol, polyvinylpyrrolidone and the like. As the solvent, various solvents such as an aqueous solvent and an organic solvent can be used.

  The granular product obtained by granulating the water-containing adsorbent obtained by the production method of the present invention is suitable as an adsorbent for a water treatment system having an adsorption vessel and an adsorption tower filled with a radioactive substance adsorbent. Can be used. In this case, the shape and size of the granular material obtained by granulating the water-containing adsorbent is filled in an adsorption vessel or packed tower, and the treated water containing cesium and / or strontium is passed through. It is preferable to appropriately adjust the shape and size so as to adapt.

In addition, the granular product obtained by granulating the water-containing adsorbent obtained by the production method of the present invention can be recovered by magnetic separation from water containing cesium and / or strontium by further containing magnetic particles. It can be used as an agent. Examples of magnetic particles include metals such as iron, nickel, and cobalt, or powders of magnetic alloys based on these metals, metal oxides such as iron trioxide, iron sesquioxide, cobalt-added iron oxide, barium ferrite, and strontium ferrite. Examples thereof include powders of magnetic system.
As a method of adding magnetic particles to a granulated granulated adsorbent in a water-containing state, for example, the above-described granulation processing operation may be performed in a state where magnetic particles are contained.

  EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these examples. Unless otherwise specified, “%” represents “mass%”. Evaluation devices and materials used in Examples and Comparative Examples are as follows.

<Evaluation equipment>
X-ray diffraction: Bruker D8 AdvanceS was used. Cu-Kα was used as the radiation source. The measurement conditions were a tube voltage of 40 kV, a tube current of 40 mA, and a scanning speed of 0.1 ° / sec.
ICP-AES: Varian 720-ES was used. The Cs and Sr adsorption tests were performed with a Cs measurement wavelength of 697.327 nm and a Sr measurement wavelength of 216.596 nm. Standard samples used were Cs: 100 ppm, 50 ppm and 10 ppm aqueous solutions containing 0.3% NaCl, and Sr: 100 ppm, 10 ppm and 1 ppm aqueous solutions containing 0.3% NaCl.

<Materials used>
No. 3 sodium silicate: manufactured by Nippon Chemical Industry Co., Ltd. (SiO ₂ : 28.55%, Na ₂ O: 9.2%, H ₂ O: 62.3%, SiO ₂ / Na ₂ O = 3.2 ).
25% liquid caustic soda: 25% sodium hydroxide for industrial use (NaOH: 25%, H ₂ O: 75%).
・ Titanium tetrachloride aqueous solution: Ishihara Sangyo TC-36
Lithium hydroxide monohydrate: (LiOH.H ₂ O: 95%, manufactured by Kanto Chemical Co., Inc.)
· Lithium silicate 35: lithium silicate solution, SiO ₂ / Li ₂ O (molar ratio) = 3.6, Nippon Chemical Industrial Co., Ltd. Titanium dioxide: Ishihara Sangyo ST-01
A potassium silicate (K ₂ O: 13.5%, SiO ₂ : 26.5%, manufactured by Nippon Chemical Industry Co., Ltd.)
・ Flake caustic potash (KOH: 95%, manufactured by Asahi Glass Co., Ltd.)
Simulated seawater: 0.3% NaCl aqueous solution containing 100 ppm of Cs and Sr was used as simulated seawater. Simulated seawater is composed of NaCl (99.5%): 3.0151 g, SrCl · 6H ₂ O (99%): 0.3074 g, CsNO ₃ (99%): 0.1481 g, H ₂ O: 996.5294 g. I got it.

[Example 1]
In a 1 L beaker, 40.0 g of No. 3 sodium silicate, 300.6 g of 25% liquid caustic soda, and 39.0 g of ion-exchanged water were weighed and mixed to obtain a mixed solution. To this mixed solution, 2.03 g of lithium hydroxide monohydrate was added and dissolved. Titanium tetrachloride aqueous solution 203.3g was dripped and mixed here over about 40 minutes with the metering pump. After completion of dropping, the obtained mixed gel was stirred for 1 hour. The molar ratio of Ti and Si in the mixed gel, the concentration of SiO _{2 in} the mixed gel, the concentration of TiO ₂ , the sodium concentration in terms of Na ₂ O, and the lithium compound relative to the total number of moles of sodium compound, potassium compound and lithium compound The ratio of the number of moles (Li / A ^* ) is shown in Table 1 below (the same applies to Examples 2 to 7 below). The mixed gel was transferred to a 500 ml pressure vessel and hydrothermally reacted in an oven at 170 ° C. for 96 hours. After completion of the reaction, the reaction product was filtered by a conventional method, the filtered product was washed, the washed product was dried, and the dried product was classified to obtain a granular adsorbent having a particle size of 300 μm or more and 600 μm or less.

The adsorbent obtained in Example 1 was sufficiently pulverized in a mortar and subjected to powder X-ray diffraction measurement under the above conditions. The obtained X-ray diffraction chart is shown in FIG. This X-ray diffraction chart is a corrected X-ray diffraction chart obtained by performing baseline correction on the chart obtained by X-ray diffraction measurement by the above method (hereinafter, Examples 2 to 13 and Comparative Example 1). The same applies to each X-ray diffraction chart shown in FIG. The synthesis of the adsorbent was repeated twice, and reproducibility was confirmed by X-ray diffraction measurement (hereinafter the same applies to Example 2 and later). As shown in FIG. 1, in the X-ray diffraction chart of the adsorbent of Example 1, the main peak of silicotitanate was observed in the range of 2θ = 10-13 °. The main peak of the titanate (I) was observed in the range of 2θ = 8 to 10 °. Therefore, it is clear that the adsorbent of Example 1 contains the silicotitanate containing Li and the titanate (I) containing Li. The ratio (%) of the main peak height of the titanate (I) to the main peak height of the silicotitanate was 32%. In addition, in the X-ray diffraction chart of the adsorbent of Example 1, the silicotitanate peak was observed in the range of 2θ = 27 to 29 °, 34 to 35 °, etc., and 2θ = 27 to 29 °, 47 to The titanate (I) peak was observed in a range of 49 ° or the like.
1 to 4, 6, and 7, “MP” is an abbreviation for a main peak, and “P.” in FIG. 2 is an abbreviation for a peak.

[Examples 2 to 5]
A granular adsorbent having a particle size of 300 μm or more and 600 μm or less in the same manner as in Example 1 except that the amounts of lithium hydroxide monohydrate, 25% liquid caustic soda and ion exchange water were changed as shown in Table 2 below. Got. However, in Examples 3 to 5, the hydrothermal reaction time was 96 hours to 72 hours. The obtained adsorbent was subjected to X-ray diffraction measurement in the same manner as in Example 1 to obtain an X-ray diffraction chart. The obtained X-ray diffraction chart is shown in FIG.
In addition, about Examples 3-5, the composition in an adsorbent was analyzed by the composition analysis of the method mentioned above, and the molar ratio of (Na + K + Li): Li and the molar ratio of Ti: Si were obtained, respectively. The results are shown in Table 2A below.

  As shown in FIG. 1, in the X-ray diffraction chart of the adsorbent of Example 2, the main peak of the titanate (I) was observed in the range of 2θ = 8 to 10 °. Therefore, it is clear that the adsorbent of Example 2 contains the titanate (I) containing Li.

As shown in FIG. 2, in the X-ray diffraction chart of the adsorbent of Example 3, the main peak of the titanate (I) was observed in the range of θ = 8 to 10 °. Therefore, it is clear that the adsorbent of Example 3 contains the titanate (I) containing Li. In addition, the titanate (I) peak was also observed in the range of 2θ = 27 to 29 °. In addition, peaks of the titanate (II) ((Li _1.81 H _0.19 ) Ti ₂ O ₅ .2H ₂ O) were observed in the range of 2θ = 27 to 29 ° and 47 to 49 °. The main peak observed at 2θ = 9 to 11 of the titanate (II) ((Li _1.81 H _0.19 ) Ti ₂ O ₅ .2H ₂ O) overlaps with the titanate (I) main peak. There is a possibility that it has become one.
The ratio of the peak height of titanate (II) observed in the range 2θ = 27 to 29 to the main peak height of titanate (I) observed in the range 2θ = 8 to 10 ° is 15%.

As shown in FIG. 3, in the X-ray diffraction chart of the adsorbent of Example 4, the titanate (I) main peak was observed in the range of θ = 8 to 10 °. Therefore, it is clear that the adsorbent of Example 4 contains the titanate (I) containing Li. In addition, the peak of the titanate (II) ((Li _1.81 H _0.19 ) Ti ₂ O ₅ .2H ₂ O) was observed in the range of 2θ = 27 to 29 ° and 47 to 49 °. The main peak observed at 2θ = 9 to 11 of the titanate (II) ((Li _1.81 H _0.19 ) Ti ₂ O ₅ .2H ₂ O) overlaps with the titanate (I) main peak. It seems to have become one.
The ratio of the peak height of titanate (II) observed in the range 2θ = 27 to 29 to the main peak height of titanate (I) observed in the range 2θ = 8 to 10 ° is 27%.

As shown in FIG. 3, in the X-ray diffraction chart of the adsorbent of Example 5, (Li _1.81 H _0.19 ) Ti ₂ O _5. A 2H ₂ O main peak was observed. This peak appears to overlap with the main peak of the titanate (I) observed in the diffraction angle (2θ) = 8 to 10 ° to form one peak.
In addition, the peak of the titanate (II) ((Li _1.81 H _0.19 ) Ti ₂ O ₅ .2H ₂ O) was observed in the range of 2θ = 27 to 29 ° and 47 to 49 °.

Example 6
81.0 g of lithium hydroxide monohydrate was added to 282.0 g of ion-exchanged water and mixed to obtain a lithium hydroxide-containing liquid. To this solution, 54.8 g of lithium silicate 35 was added to form a precipitate. Next, 203.0 g of titanium tetrachloride aqueous solution was mixed to obtain a mixed gel. The obtained mixed gel was transferred to a 500 ml pressure vessel and hydrothermally reacted in an oven at 170 ° C. for 72 hours. The reaction product was filtered by a conventional method, the filtrate was washed, the washed product was dried, and the dried product was classified to obtain a granular adsorbent having a particle size of 300 μm or more and 600 μm or less. The obtained adsorbent was subjected to X-ray diffraction measurement in the same manner as in Example 1. The obtained X-ray diffraction chart is shown in FIG.

Example 7
Instead of adding lithium silicate 35 first to the lithium hydroxide-containing liquid and then adding the titanium tetrachloride aqueous solution later, the titanium tetrachloride aqueous solution is added to the lithium hydroxide-containing liquid first to precipitate. A granular adsorbent having a particle size of 300 μm or more and 600 μm or less was obtained in the same manner as in Example 6, except that lithium silicate 35 was added later to form a mixed gel. The obtained adsorbent was subjected to X-ray diffraction measurement in the same manner as in Example 1. The obtained X-ray diffraction chart is shown in FIG.

As shown in FIG. 3, in the X-ray diffraction chart of the adsorbent of Example 6, a main peak of (Li _1.81 H _0.19 ) Ti ₂ O ₅ .2H ₂ O is observed in the range of 2θ = 9 to 11 °. In addition, peaks of (Li _1.81 H _0.19 ) Ti ₂ O ₅ .2H ₂ O were also observed in the other ranges of 27 to 29 ° and 36 to 38 °.

As shown in FIG. 3, in the X-ray diffraction chart of the adsorbent of Example 7, a main peak of (Li _1.81 H _0.19 ) Ti ₂ O ₅ .2H ₂ O is observed in the range of 2θ = 9 to 11 °. It was. In addition, peaks of (Li _1.81 H _0.19 ) Ti ₂ O ₅ .2H ₂ O were also observed in the range of 2θ = 27 to 29 ° and 36 to 38 °.

Example 8
As the first alkali metal hydroxide, 131.2 g of lithium hydroxide monohydrate was dispersed and dissolved in 468.8 g of ion-exchanged water to obtain a first lithium hydroxide liquid. This was added to 404 g of titanium tetrachloride aqueous solution to cause a neutralization reaction to obtain a reaction solution. The concentration of titanium in the reaction solution was 3.69% by mass, and the molar ratio A ′ / Ti between the sum of alkali metals and titanium was 4.05. Separately from this reaction liquid, a second lithium hydroxide liquid in which 97.7 g of lithium hydroxide monohydrate as a second alkali metal hydroxide is dispersed and dissolved in 300 g of ion-exchanged water is prepared. Was added to the reaction solution to obtain a mixed slurry. The ratio A ′ / Ti of the addition amount of the second alkali metal hydroxide to Ti (OH) ₄ in the reaction solution was 1.72. The ratio of the number of moles of lithium hydroxide to the total number of moles of the first and second alkali metal hydroxides (Li / A ^** ) was 1. The mixed slurry was stirred at 100 ° C. for 1 hour. Next, the mixed slurry was transferred to a pressure vessel and subjected to a hydrothermal reaction by standing in an oven at 170 ° C. for 72 hours. The reaction product was filtered by a conventional method, the filtrate was washed, the washed product was dried, and the dried product was classified to obtain a granular adsorbent having a particle size of 300 μm or more and 600 μm or less. The obtained adsorbent was subjected to X-ray diffraction measurement in the same manner as in Example 1. The obtained X-ray diffraction chart is shown in FIG.

As shown in FIG. 4, a main peak of (Li _1.81 H _0.19 ) Ti ₂ O ₅ .2H ₂ O was detected in the range of 2θ = 9 to 11, and 27.5 to 29.5 °, 36 to 38 °, 47 The peak of (Li _1.81 H _0.19 ) Ti ₂ O ₅ .2H ₂ O was also observed in the range of ˜49 °.

[Comparative Example 1]
In this comparative example, titanium dioxide was used instead of titanium tetrachloride as the titanium source.
No. 3 sodium silicate 90 g, caustic soda aqueous solution 121.2 g and ion-exchanged water 506.1 g were mixed and stirred to obtain a mixed solution. Instead of the titanium tetrachloride aqueous solution, a slurry in which 68.2 g of titanium dioxide was mixed and dispersed in 270 g of ion exchange water was continuously added to the above mixture over 5 minutes to obtain a mixed gel. The mixed gel was allowed to age at room temperature for 1 hour after the addition of titanium dioxide. This mixed gel was put into an autoclave and heated to 170 ° C. over 1 hour, and then reacted for 24 hours with stirring while maintaining this temperature. The reaction product was filtered by a conventional method, the filtrate was washed, the washed product was dried, and the dried product was classified to obtain a granular adsorbent having a particle size of 300 μm or more and 600 μm or less. The X-ray diffraction chart of the obtained adsorbent is shown in FIG. According to this chart, the silicotitanate peak was observed in the range of 2θ = 11 to 13 °, and the titanic acid (I) and titanic acid (II) peaks were not observed. In addition, peaks of Na ₂ TiOSiO and TiO ₂ were observed.

<Adsorption test of Cs and Sr>
0.50 g of the obtained adsorbent was put in a 100 ml plastic container, 100.00 g of simulated seawater was added, the cap was put on, and the mixture was inverted and shaken 10 times. Then, it left still for 24 hours. After standing still, it was inverted again 10 times, and then the test solution was filtered with 5C filter paper, and the filtrate obtained by filtration was collected. Using the collected filtrate as a target, the concentration (ppm) of Cs and Sr in the filtrate was measured using ICP-AES. For each of Cs and Sr, the adsorption rate (%) was obtained by dividing the concentration difference obtained by subtracting the concentration after the adsorption test from the concentration in the simulated seawater before the adsorption test by the concentration in the simulated seawater before the adsorption test. . The results are shown in Table 3 below.

  The adsorbents of Examples 1 to 8 containing the silicotitanate containing Li, the titanate (I) or the titanate (II) have a high Sr adsorption performance of 75% or more. showed that. Further, the adsorbents of Examples 1 to 7 also had a high Cs adsorption rate of 36.3% or more. Further, although the adsorbent of Example 8 had a low Cs adsorption rate, the Sr adsorption rate was significantly high at 95%. On the other hand, the adsorbent of Comparative Example 1 was inferior in the adsorption rate of Cs and Sr. From this result, it is clear that the adsorbent of the present invention in which Li is contained in silicotitanate, the titanate (I), or the titanate (II) has a high adsorption performance of Cs and / or Sr. It is. In particular, the adsorbent of Example 1 in which the main peak of the silicotitanate and the main peak of the titanate (I) were observed in the X-ray diffraction measurement had particularly high adsorption performance for both Cs and Sr. there were. In addition, although the silicotitanate crystal peak is not observed in Examples 2 to 7, especially Examples 5 and 6, the high Cs adsorption performance is that the amorphous silicotitanate, particularly amorphous and contains Li. This is presumably due to the presence of the silicotitanate.

Examples 9 to 13 below are examples in which an adsorbent was produced using K as an alkali compound instead of Na or in addition to Na.
[Examples 9 to 13]
In a 1 L beaker, weighed and mixed No. 3 sodium silicate or A potassium silicate, 25% liquid caustic soda, flake caustic potash, and ion-exchanged water, and then added lithium hydroxide as needed. And dissolved by heating. A titanium tetrachloride aqueous solution was dropped and mixed with the metering pump over about 40 minutes to obtain a mixed gel. For the molar ratio of Ti and Si in the mixed gel, the concentration of SiO _{2 in} the mixed gel, the concentration of TiO ₂ , the sodium concentration in terms of Na ₂ O, and the total number of moles of sodium compound, potassium compound and lithium compound, The ratio of the number of moles of lithium compound (Li / A ^* ) and the ratio of the number of moles of potassium compound to the total number of moles (K / A ^* ) are shown in Table 5 below. The resulting mixed gel was stirred for 1 hour. Next, the mixed gel was transferred to a 500 ml pressure vessel and hydrothermally reacted in an oven at 170 ° C. for 96 hours. After completion of the reaction, the reaction product was filtered by a conventional method, the filtrate was washed, the washed product was dried, and the dried product was classified to obtain a granular adsorbent having a particle size of 300 μm or more and 600 μm or less. The obtained adsorbent was subjected to X-ray diffraction measurement in the same manner as in Example 1 to obtain an X-ray diffraction chart. The obtained X-ray diffraction charts are shown in FIGS.

  As shown in FIG. 6, in the X-ray diffraction chart of the adsorbent of Example 9, the titanate (I) main peak was observed in the range of 2θ = 8 to 10 °. Therefore, it is clear that the adsorbent of Example 9 contains the titanate (I) containing Li. In addition, in the X-ray diffraction chart of the adsorbent of Example 9, the titanate (I) peak was also observed in the range of 2θ = 47 to 49 ° or the like.

  As shown in FIG. 6, in the X-ray diffraction chart of the adsorbent of Example 10, the main peak of silicotitanate was observed in the range of 2θ = 10-13 °. In addition, the titanate (I) peak was observed in the range of 2θ = 8 to 10 °. Therefore, it is clear that the adsorbent of Example 10 contains the silicotitanate containing Li and the titanate (I) containing Li. The ratio of the main peak height of the titanate (I) to the main peak height of the silicotitanate was 28%. In addition, in the X-ray diffraction chart of the adsorbent of Example 10, the silicotitanate peak was observed in the range of 2θ = 27 to 29 °, 33.5 to 35.5 °, and the like, and 2θ = 47. The titanate (I) peak was also observed in a range of ˜49 ° or the like.

As shown in FIG. 7, in the X-ray diffraction chart of the adsorbent of Example 11, (Li _1.81 H _0.19 ) Ti ₂ O ₅ .2H which is titanate (II) in the range of 2θ = 9 to 11 °. _{A 2} O main peak was observed. In addition, peaks of (Li _1.81 H _0.19 ) Ti ₂ O ₅ .2H ₂ O were also observed in the range of 27 to 29 ° and 36 to 38 °.

As shown in FIG. 7, in the X-ray diffraction chart of the adsorbent of Example 12, (Li _1.81 H _0.19 ) Ti ₂ O ₅ .2H which is titanate (II) in the range of 2θ = 9 to 11 °. _{A 2} O main peak was observed. In addition, peaks of (Li _1.81 H _0.19 ) Ti ₂ O ₅ .2H ₂ O were also observed in the range of 27 to 29 ° and 36 to 38 °.

As shown in FIG. 7, in the X-ray diffraction chart of the adsorbent of Example 13, (Li _1.81 H _0.19 ) Ti ₂ O ₅ .2H which is titanate (II) in the range of 2θ = 9 to 11 °. _{A 2} O main peak was observed. In addition, peaks of (Li _1.81 H _0.19 ) Ti ₂ O ₅ .2H ₂ O were also observed in the range of 27 to 29 ° and 36 to 38 °.

  For the adsorbents obtained in Examples 9 to 13, the same adsorption tests as those in Examples 1 to 8 and Comparative Example 1 were performed. The results are shown in Table 6 below.

  As is apparent from the description in Table 6 above, it can be seen that the adsorbent of the present invention containing K instead of Na or in addition to Na also has a high adsorption performance of Cs and / or Sr.

Claims (17)

General formula (1); A ₄ Ti ₄ Si ₃ O ₁₆ .nH ₂ O (wherein A represents at least one alkali metal selected from the group consisting of Na, K and Li, and n is a number from 0 to 8) A silicotitanate represented by:
General formula (2); A ₄ Ti ₉ O ₂₀ · mH ₂ O (wherein A represents at least one alkali metal selected from the group consisting of Na, K and Li, and m represents a number of 0 to 10). ) And the general formula (3); (A _x H _(2-x) ) Ti ₂ O ₅ .mH ₂ O (wherein A is from Na, K and Li) At least one alkali metal selected from the group consisting of: x represents a number satisfying 0.1 ≦ x ≦ 2, and m represents a number from 0 to 10.
An adsorbent for cesium or strontium, wherein one or two or more compounds selected from the above, and A in at least one of the one or more compounds contains Li.   In the adsorbent, when the diffraction angle (2θ) using Cu-Kα as an X-ray source is measured by X-ray diffraction in the range of 5 to 80 °, one or more peaks of the silicotitanate are observed and the titanium The adsorbent according to claim 1, wherein at least one peak of the acid salt (I) is observed.   When the X-ray diffraction measurement was performed in the range of the diffraction angle (2θ) using Cu—Kα with the adsorbent as an X-ray source in the range of 5 to 80 °, the main peak of the titanate (I) was found to have a diffraction angle (2θ The adsorbent according to claim 1 or 2, which is observed in a range of 8 to 10 °.   When the X-ray diffraction measurement was performed with the adsorbent used as an X-ray source and Cu-Kα as a diffraction angle (2θ) in the range of 5 to 80 °, the main peak of the titanate (II) was found to have a diffraction angle (2θ The adsorbent according to any one of claims 1 to 3, which is observed in a range of 9 to 11 °.   It is a powder form or a granular form, Adsorbent as described in any one of Claims 1-4. General formula (1); A ₄ Ti ₄ Si ₃ O ₁₆ .nH ₂ O (wherein A represents at least one alkali metal selected from the group consisting of Na, K and Li, and n is a number from 0 to 8) A silicotitanate represented by:
General formula (2); A ₄ Ti ₉ O ₂₀ · mH ₂ O (wherein A represents at least one alkali metal selected from the group consisting of Na, K and Li, and m represents a number of 0 to 10). ) And the general formula (3); (A _x H _(2-x) ) Ti ₂ O ₅ .mH ₂ O (wherein A is from Na, K and Li) At least one alkali metal selected from the group consisting of: x represents a number satisfying 0.1 ≦ x ≦ 2, and m represents a number from 0 to 10.
A method for producing an adsorbent for cesium or strontium, comprising one or two or more compounds selected from the above, wherein A in at least one of the one or two or more compounds contains Li Because
A first step of obtaining a mixed gel by mixing a silicic acid source, an alkali metal compound, titanium tetrachloride, and water;
A second step of hydrothermal reaction of the mixed gel obtained in the first step,
As the alkali metal compound, at least one selected from a sodium compound and a potassium compound and a lithium compound are used, or a lithium compound is used. In the first step, the molar ratio of Ti and Si contained in the mixed gel is Ti / Si. = A method for producing an adsorbent of cesium or strontium, in which a silicate source and titanium tetrachloride are added so that the ratio is 0.5 to 3.0.   The method for producing an adsorbent according to claim 6, wherein, in the first step, the silicate source is sodium silicate or activated silicate obtained by cation exchange of an alkali silicate.   The said 1st process WHEREIN: The silicic acid source is sodium silicate, What mixed this sodium silicate and an alkali metal compound, and titanium tetrachloride are mixed, The said mixed gel is obtained. Manufacturing method of the adsorbent.   In the first step, the silicic acid source is activated silicic acid obtained by cation exchange of alkali silicate, and the mixture of the active silicic acid and titanium tetrachloride is mixed with the alkali metal compound to The method for producing an adsorbent according to claim 7, wherein a mixed gel is obtained. In the first step, the alkali metal compound is added so that the total concentration of sodium, potassium and lithium in the mixed gel is 0.5% by mass or more and 15% by mass or less in terms of Na ₂ O. The manufacturing method of the adsorption agent as described in any one of these. In the first step, the silicate source is sodium silicate, and the total concentration of sodium, potassium and lithium in the mixed gel is 2.0% by mass or more and 4.5% by mass or less in terms of Na ₂ O. The method for producing an adsorbent according to claim 10, wherein the alkali metal compound is added. In the first step, the silicic acid source is activated silicic acid obtained by cation exchange of alkali silicate, and the total concentration of sodium, potassium and lithium in the mixed gel is 1% by mass or more in terms of Na ₂ O 6 The method for producing an adsorbent according to claim 10, wherein the alkali metal compound is added so as to be less than or equal to mass%. In the first step, the total amount of the SiO ₂ equivalent silicic acid source concentration and the TiO ₂ equivalent titanium tetrachloride concentration in the mixed gel is 2.0 mass% or more and 40 mass% or less, and A ′ in the mixed gel Silicate source so that the molar ratio of ₂ O to SiO ₂ is A ′ ₂ O / SiO ₂ = 0.5 or more and 3.0 or less (wherein A ′ represents Na, K and Li). The method for producing an adsorbent according to any one of claims 6 to 12, wherein titanium tetrachloride is added.   The method for producing an adsorbent according to any one of claims 6 to 13, wherein in the first step, the alkali metal compound is a hydroxide.   The method for producing an adsorbent according to any one of claims 6 to 14, wherein the water-containing reaction product obtained by the hydrothermal reaction in the second step is dried, and the obtained dry product is crushed or pulverized. .   The hydrous reaction product obtained by the hydrothermal reaction in the second step is extruded through an aperture member in which a plurality of apertures are formed to obtain a rod-shaped product, and the obtained rod-shaped product is dried. The method for producing an adsorbent according to any one of claims 6 to 14.   The method for producing an adsorbent according to claim 16, wherein the rod-shaped molded body is dried to obtain a dried molded body, and the dried molded body is crushed or pulverized.