JP2003236371A - Highly selective barium adsorbent and method for the same manufacturing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a barium adsorbent capable of highly selectively separating and recovering a trace amount of harmful Ba<SP>2+</SP>ion dissolved in a solution and to provide a method for simply manufacturing the adsorbent. <P>SOLUTION: The highly selective barium adsorbent having high Ba<SP>2+</SP>ion selectivity is obtained by extracting lithium and alkali earth metal using an acid from a precursor composite oxide which is obtained by substituting alkali earth metal for a portion of lithium in a lithium manganese composite oxide represented by a general formula Li<SB>2</SB>MnO<SB>3</SB>and having a general formula Li(<SB>2-x)</SB>A<SB>x</SB>MnO<SB>3</SB>(wherein the value x is in the range of 0≤x≤1 and A represents an alkali earth metal). The method for manufacturing the barium adsorbent, a barium separating method and a barium adsorbing and separating apparatus are also provided. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a highly selective barium adsorbent, a method for producing the same, and more specifically, a lithium manganese composite oxide Li ₂ MnO ₃
The precursor composite manganese oxide synthesized by substituting a part of the lithium in the composite manganese oxide with an alkaline earth metal such as calcium or strontium, and further subjecting the composite manganese oxide to lithium and alkaline earth metal in the composite manganese oxide. A method for synthesizing a highly selective barium adsorbent composed of hydrogen-type manganese composite oxide by a simple operation process of resubstituting hydrogen with hydrogen,
And a new highly selective barium adsorbent obtained by the method, which can be applied to a multi-component treated water system containing many kinds of cations. The highly selective barium adsorbent of the present invention is used for separating harmful Ba ²⁺ ions contained in trace amounts in, for example, mineral water and industrial wastewater, leaked water from waste disposal sites, and inland water such as oceans, rivers, lakes and groundwater. -Useful for removal.

[0002]

2. Description of the Related Art Advances in science and technology have brought us many benefits, but on the other hand, they have brought about environmental problems on a global scale that put a burden on the environment and threaten the survival of mankind. Areas where environmental improvement is required include oceans, rivers, lakes,
The air and soil are extremely diverse, and various technologies related to purification treatment have been developed and put to practical use in their respective fields. Among them, it is important to develop a technology for treating Ba ²⁺ ions contained in a small amount in drainage water or land water.

Barium is, for example, a getter for a vacuum tube,
It is an element widely used as a raw material for alloys, glass, enamel, chemicals, etc. Its main ore is barite (BaSO).
₄ ) and poisonous heavy stones (BaCO ₃ ) (edited by Michinori Oki et al., Chemical Dictionary, p. 1098, Tokyo Kagaku Dojin (199).
4)). Barium contains 390 ppm in the crust and its dissolved concentration in seawater is 0.03 ppm (Translated by Yoshihito Matsui et al., General Geochemistry, pp.234-235, Iwanami Shoten (1979)). Also, barium is contained in various living bodies, and 0.3 ppm is contained in the human body (Translated by Yoshito Matsui et al., General Geochemistry, p. 275, Iwanami Shoten (197).
9)). Its chemical properties are similar to those of calcium and strontium, but its action is more remarkable, and the +2 oxidation state is stable, and a strong ionic bond is formed.
The toxicity of Ba ²⁺ ions has been previously pointed out (Translated by Tetsuya Sakamoto, Handbook of Poisoning, pp 76-77, Medical Science International (200
1)), mineral and industrial wastewater, leaked water from waste disposal sites and the ocean,
Ba ²⁺ contained in trace amounts in land water such as rivers, lakes and groundwater
Removal of ions was an important issue.

The unit operations generally used in water treatment include biological treatment, coagulation / precipitation treatment, filtration, oxidative decomposition, adsorption and the like. Among these purification techniques, the adsorption method plays a large role, and examples of the adsorbent include activated carbon, ion exchange resin, biological carrier filter, crystallization material (iron-removing / manganese-removing filter, etc.) and the like. Among these, adsorption treatment with activated carbon is frequently used (for example, supervision by Takeuchi Shira, properties of porous materials and their applications, pp.494-525, Fuji Techno System (1999)). Activated carbon is a hydrophobic adsorbent and is mainly used for adsorption / separation of various organic components such as solvent recovery, deodorization, gas purification, etc. Adsorption / separation of inorganic ions is a dechlorination treatment. Examples (for example, supervision by Takeuchi Shira, properties of porous materials and their applications, pp.504-50
5, except Fuji Techno System (1999)), the adsorption treatment is carried out exclusively by ion exchange resin (Kuroda Rokuro et al., Co-translation, ion exchange, pp.37-38, Maruzen (19).
81)).

Cation exchange resins have been widely used as adsorbents for the removal of cations in treated water such as Ba ²⁺ ions (NEW DEVELOPMENTS I).
NION EXCHANGE: Materials, F
undamentals, and Applicati
ons / Proceedings of ICIE '9
1, Tokyo). The selective adsorptivity of ion exchange resins for various ions is governed mainly by the factors that govern electrostatic interaction with exchange groups, such as the degree of hydration of ions and their size and valence. The selectivity coefficient of the resin for alkaline earth metal ions is Ba ²⁺ > Sr ²⁺ > C
It decreases in the order of a ²⁺ > Mg ²⁺ , and the smaller the hydrated ion diameter, the higher the selectivity.

However, the difference in the selectivity coefficient between cations is not so large (Gaku Senoo et al., Ion Exchange.
Basics of advanced separation technology, pp. 9-10, Kodansha Scientific (1991)), the effective ion exchange capacity of the cation exchange resin decreases due to coexisting ions in a treated water system having a low Ba ²⁺ ion concentration and containing many components.
As a solution to such a problem, a chelate resin having high selectivity to a specific ionic species is commercially available, but since it is expensive, leakage water from a disposal site such as general waste and industrial waste or Application to multi-component systems such as rivers and lakes such as inland water is inconvenient in terms of economy. Therefore, it has been desired to develop an inexpensive and highly selective barium adsorbent that can be applied to a multi-component treated water system.

On the other hand, crystalline inorganic ion exchangers are generally known to have higher selectivity for specific ions or groups and superior physicochemical properties such as heat resistance and radiation resistance as compared with ion exchange resins. I have ("Topics
in Inorganic & General Che
"mistry", Elevivier, Amsterd
am (1964)). Therefore, crystalline inorganic ion exchangers are used as separation / concentration materials in analytical chemistry, removal of radionuclides from reactor cooling water and waste liquid, and waste disposal (Int.
er. Atomic Energy Efficacy T
electrical Rept. Series No. Three
56 (1993)) and other fields are expected to be used, and thus many types of inorganic ion exchangers have been conventionally synthesized,
Their properties have been investigated (eg A. Clea.
rfield Ed. , "Inorganic Ion
Exchange Materials ”, CRCp
less, Boca Raton, Florida (1
982)).

The various characteristics of the inorganic ion exchanger as described above are due to the expression of the ion sieving effect due to the steric regulation of the micropores in the exchanger having a rigid crystal structure as compared with the ion exchange resin (edited by Manobu Senoo et al. , Ion Exchange-Basics of Advanced Separation Technology, pp. 73-82, Kodansha Scientific (1991)). In fact, so far, Li ⁺ ions (for example, Yoshiro Onodera et al., The Ceramic Society of Japan, 97,
884-894 (1989)), Na ⁺ ion (MA)
be, “Inorganic Ion Exchange
e Materials ", Ed. A. Clearfi
eld, p. 161, CRC Press, Boca
Raton, Florida (1982), Cs ⁺ ions (eg JF Jr. Walker et a.
l. , Sep. Sci. Technol, 34, 116
7-1181 (1999)), and Sr ²⁺ ion (E.
A. Berens et al. , Microporo
usMater. , 11, 65-75 (1997)), there is known an ion sieve type synthetic inorganic ion exchanger exhibiting a specific adsorptivity.

Ba ²⁺ ion is a kind of polyvalent ion and has the smallest hydrated ion diameter among alkaline earth metal ions, so that it is an inorganic ion exchanger having selectivity for the Ba ²⁺ ion. Is relatively large. For example, X-type, A-type, and Y-type zeolite (DW Breck, “ZEOLIT
E MOLECULAR SIEVES / Struc
ure, Chemistry and Use ”, p
p. 529-592, John Wiley & So
ns, New York (1974) and clay minerals (Haruo Shiramizu, "Clay Mineralogy", p.40, Asakura Shoten (199)
The selection coefficient for the alkaline earth metal ion of 8)) decreases in the order of Ba ²⁺ ⊇Sr ²⁺ ⊇Ca ²⁺ > Mg ²⁺ ,
Ion species having a larger hydrated ion diameter tend to be smaller.
However, between both alkaline earth metal ions, because the difference is not clear, from the viewpoint of the separation and recovery of Ba ²⁺ ions efficiently, ion sieve type with specificity adsorptive property to the Ba ²⁺ ions The development of barium adsorbent has been eagerly awaited.

[0010]

[Problems to be Solved by the Invention]
In view of the above-mentioned conventional technology, the inventors of the present invention have²⁺
It is possible to solve the technical problem of ion separation and recovery
With the goal of developing new new barium adsorbents
As a result of repeated research, the general formula Li₂ MnO₃ Represented by
The lithium in the lithium-manganese composite oxide
Partial with alkaline earth metals such as lucium and strontium
The precursor composite manganese oxide synthesized by substitution was acid treated.
Replaces lithium and alkaline earth metals in the structure with hydrogen
General formula obtained by_(2-xy) A_(xy) H_y MnO₃ 
(Respectively, the value of x in the formula is 0 ≦ x ≦ 1, and the value of y is
Is 0 <y <1. In addition, A and H are
Indicates potash earth metal and hydrogen. ) Is a compound represented by
Ba²⁺It specifically adsorbs ions and
Ba from the coexisting solution²⁺Highly selective adsorption / separation of ions
They have found that they can do so and have completed the present invention. sand
That is, the present invention is based on Ba²⁺Has specific adsorptivity for ions
Ion-sieve type highly selective barium adsorbent and its simple production
It is intended to provide a manufacturing method. Also,
The present invention is directed to Ba from an alkaline earth metal ion coexisting solution.
²⁺High selection capable of highly selective adsorption and separation of ions
The purpose is to provide a selective barium adsorbent.
is there. Furthermore, the present invention provides the above-mentioned highly selective barium adsorbent.
The barium in the solution to be treated is brought into contact with the solution to be treated.
Separation method, the highly selective barium adsorbent is Ba²⁺ I
A barium adsorption / separation device filled in the ON separation means
It is intended to be provided.

[0011]

The present invention for solving the above-mentioned problems comprises the following technical means. (1) Precursor composite manganese oxide represented by the general formula Li _(2-x) A _x MnO ₃ (where the value of x is 0 ≦ x ≦ 1 and A represents an alkaline earth metal). A highly selective barium adsorbent comprising a hydrogen-type manganese composite oxide obtained by substituting lithium and alkaline earth metals in a product with hydrogen. (2) In formula Li in _{(2-xy) A (xy} ) H y MnO 3 ( where the value of x is a value of 0 ≦ x ≦ 1, y is 0 <y <1,
A and H represent alkaline earth metal and hydrogen, respectively. ) Consisting of a hydrogen-type manganese composite oxide represented by
The highly selective barium adsorbent according to (1) above. (3) the general formula Li _(2-xy) was replaced with hydrogen by the precursor composite manganese oxide lithium and alkaline earth metal to an acid treatment in the product according to _{(1) A (xy) H} y MnO 3 ( In the formula, the value of x is 0 ≦ x ≦ 1, the value of y is 0 <y <1, and
A and H represent alkaline earth metal and hydrogen, respectively. ) The method for producing a highly selective barium adsorbent, which comprises converting the hydrogen-type manganese composite oxide represented by (4) B in the solution to be treated by bringing the highly selective barium adsorbent according to (1) or (2) into contact with the solution to be treated
A barium separation method characterized by selectively adsorbing and separating a ²⁺ ions. (5) A barium adsorption / separation device, characterized in that the highly selective barium adsorbent according to (1) or (2) is filled in a Ba ²⁺ ion separation means.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the present invention will be described in more detail. In the present invention, a composition-converted lithium-manganese composite oxide in which a part of lithium in lithium-manganese composite oxide Li ₂ MnO ₃ is replaced with an alkaline earth metal is used as a starting material. This general formula Li _(2-x) A _x M
The composite manganese oxide represented by nO ₃ (where the value of x in the formula is 0 ≦ x ≦ 1 and A represents an alkaline earth metal) is the lithium-manganese composite oxide Li ₂ MnO ₃ described above.
It is synthesized by substituting a part of lithium in the alkaline earth metal such as magnesium, calcium, strontium, and barium.

The synthesis method and conditions will be specifically described. Li ₂ MnO ₃ can be used, for example, lithium carbonate,
Magnesium carbonate, calcium carbonate, manganese carbonate, strontium carbonate, barium carbonate, lithium chloride, magnesium chloride, calcium chloride, strontium chloride,
Barium chloride, manganese chloride, lithium oxide, magnesium oxide, calcium oxide, strontium oxide, barium oxide, manganese oxide, etc. are added so as to have an ideal chemical composition, and after grinding and mixing, 1 at 500 to 900 ° C. in the atmosphere. The precursor composite manganese oxide is produced by heating for -24 hours and appropriately pulverizing and sizing this heated product.

Next, the precursor composite manganese oxide obtained by the above synthesis method is treated with an acid to replace the lithium and alkaline earth metal in the structure with hydrogen again to give the general formula L
i _{(2- xy )} A _(xy) H _y MnO ₃ (where x is 0 ≦
x ≦ 1, and the value of y is 0 <y <1. A and H represent alkaline earth metal and hydrogen, respectively. )
A hydrogen-type manganese composite oxide represented by is synthesized. Concretely explaining the synthesis method and conditions thereof, acids such as hydrochloric acid, nitric acid, and sulfuric acid are added to the precursor composite manganese oxide, and the mixture is shaken at room temperature to 50 ° C. for 1 to 48 hours, and then solid-liquid is separated, The solid phase is washed with distilled water and then dried by heating at 40 to 100 ° C to produce the target compound. Here, the general formula Li _(2-xy) corresponding to the replacement of hydrogen A _(xy) H _y Mn
The value of y in O ₃ can be adjusted by changing the conditions such as the concentration of the acid solution used for the treatment, the treatment temperature and the treatment time.

Thus, the present invention provides the general formula Li _(2-x)
In a precursor composite manganese compound composed of a composition-converted lithium-manganese composite oxide represented by A _X MnO ₃ (where the value of x in the formula is 0 ≦ x ≦ 1, and A represents an alkaline earth metal). Is a hydrogen-type manganese composite oxide obtained by substituting hydrogen for lithium and alkaline earth metal, and is a highly selective barium adsorbent. Examples of the precursor composite manganese oxide include Li ₂ MnO ₃ , LiMgMnO ₃ , and LiCaMn in which x = 0 and 1 in the above general formula.
O ₃ , LiSrMnO ₃ , LiBaMnO ₃ , and 0 <
Illustrative are alkaline earth metal substitutes having various values in the range of x <1. Generation of precursor compound in the powder X-ray diffraction pattern of the sample, a diffraction peak based on the basic structure of Li ₂ MnO ₃ (d value = 4.75,2.02,2.
42, 1.42Å) is easily confirmed.

In the present invention, the above precursor compound is treated with an acid.
The metal in the compound is partially replaced by hydrogen
Adds ionic sieving function by converting the composition into multiple stages
A method for producing a highly selective barium adsorbent characterized by comprising:
Is. As these hydrogen-type manganese composite oxides,
The above general formula Li_(2-xy) A_(xy) H_y MnO₃ smell
Li for x = 0 or 1 and y = 0.5_1.5 H_0.5 Mn
O₃ , Li_0.5 Mg_{0. Five} H_0.5 MnO₃ , Li_0.5 Ca
_0.5 H_0.5 MnO₃ , Li_0.5 Sr_0.5 H_0.5 MnO
₃ , Li_0.5 Ba_0.5 H_0.5 MnO₃ Other than 0 <x ≦ 1
And various compositions having values within the range of 0 <y <1
To be done.

The formation of the highly selective barium adsorbent was carried out by using Li ₂ Mn in the powder X-ray diffraction pattern of the acid-treated sample.
Of the diffraction peaks assigned to O ₃ , the strongest diffraction peak (d
It is easily confirmed that a shoulder peak (d value = about 4.6Å) newly appears on the high angle side of the value = 4.75Å). This shoulder peak is due to the fact that the lithium or alkaline earth metal element in the precursor compound is replaced by hydrogen having a small ionic diameter, resulting in a new crystalline phase in which the lattice spacing is slightly shrunk compared to the basic structure of Li ₂ MnO ₃ . Probably due to generation. A similar change in the basic structure of the complex oxide due to the acid treatment is due to the fact that the lithium / titanium complex oxide Li ₂ TiO ₃ (Yoshiro Onodera et al., Journal of the Ceramic Society of Japan, 97, 884, which is known to have a specific adsorption property for Li + ions). -89
4 (1989)) and lithium-manganese composite oxide L
iMn ₂ O ₄ (K. Onodera et al., J. Ceram. So
c. Jap. , 100, 767-774 (1992)).
Is also confirmed.

In the present invention, the highly selective barium adsorbent made of the hydrogen-type manganese composite oxide produced by the above method is brought into contact with a solution to be treated containing Ba ²⁺ ions, and the Ba in the solution to be treated is brought into contact therewith. Provided is a barium separation method for selectively adsorbing and separating ²⁺ ions. INDUSTRIAL APPLICABILITY The method of the present invention is suitably applied to, for example, separation and removal of minute amounts of Ba ²⁺ ions contained in mine / industrial wastewater, leaked water from waste disposal sites, and inland water such as the ocean, rivers, lakes and groundwater. Also, it is applicable to a multi-component treated water system containing many kinds of cations. Further, the present invention provides a barium adsorption / separation device in which the Ba ²⁺ ion separation means is filled with the above-mentioned highly selective barium adsorbent. The Ba ²⁺ ion separation means and the separation device are exemplified by, for example, those obtained by filling the separation tube or the like with the highly selective barium adsorbent, and the shape, structure, system, etc. are designed as appropriate according to the purpose of use. It does not have to be particularly limited.

[0019]

The highly selective barium adsorbent of the present invention has a general formula Li _(2-x) A _x MnO ₃ (where x is 0 ≦ x ≦ 1 and A is alkaline earth ₎ as the first step. shows a metalloid. After obtaining a precursor compound represented by), Li ₂ which processes the precursor compound with an acid solution as the second stage of metal ions of the precursor compound in the partially substituted with hydrogen ion MnO ₃
It is a hydrogen-type inorganic ion adsorbent that retains the basic structure of.
Ba ²⁺ ions are adsorbed and separated from the solution to be treated by the high selective adsorption of barium by the fine pores having an ion sieving function formed in the hydrogen-type inorganic ion adsorbent. The highly selective barium adsorbent of the present invention has a high adsorption / separation effect for a trace amount of Ba ²⁺ ions in various solutions to be treated having a high coexisting cation concentration. Therefore, by using the highly selective barium adsorbent according to the present invention, the selective adsorption / separation of Ba ²⁺ ions from various solutions to be treated can be easily performed with high efficiency. The highly selective barium adsorbent of the present invention makes it possible to highly selectively adsorb and separate Ba ²⁺ ions from an alkaline earth metal ion coexisting solution.

[0020]

EXAMPLES Next, the present invention will be specifically described based on examples, but the present invention is not limited to the following examples. 1. Synthesis of highly selective barium adsorbent sample (1) Preparation of precursor compound sample For synthesis of precursor composite manganese oxide, five kinds of commercially available special grade reagent powders (lithium carbonate, calcium carbonate, manganese carbonate, strontium carbonate, and Barium carbonate) was used as the starting material. A predetermined amount of each reagent powder was weighed so that the precursor compound shown in Table 1 had the ideal chemical composition. The weighed amount in Table 1 is a value after the purity of the reagent is corrected. The weighing reagent powder was ground and mixed in an automatic mortar equipped with an agate mortar for 30 minutes, and 4 g of each powder was dispensed into a porcelain crucible having a content of 30 ml. Place this crucible in the atmosphere for 5
It heated in the electric muffle furnace of each temperature of 50 degreeC, 650 degreeC, 750 degreeC, and 850 degreeC for 8 hours. Then, the crucible was gradually cooled to room temperature, the contents were taken out, and the crucible was ground and mixed again in an agate mortar. The milled mixture was transferred to the magnetic crucible and heated at the same temperature for 4 hours. The reheated product was ground in an agate mortar and then passed through a 100-mesh sieve to give a precursor compound sample.

[0021]

[Table 1]

(2) Acid Treatment of Precursor Compound Samples 1.5 of various precursor compound samples obtained in (1) above
Take each g in a glass sample tube with a sealed capacity of 50 ml and add 20 ml of 2M (M = mol / dm ³ ) hydrochloric acid.
Was added, and the mixture was gently shaken in a dry oven at 40 ° C. for 24 hours. After that, the hydrochloric acid solution was replaced with a fresh one, and the mixture was further shaken for 24 hours, and then the solid-liquid was separated by suction filtration. The solid phase on the filter paper was repeatedly washed with distilled water until no chloride ions were found in the washing liquid, and then dried by heating in a dry oven at 50 ° C. for 24 hours to obtain a target barium adsorbent sample.

2. Adsorption test method (1) Add predetermined amounts of commercially available special grade reagents magnesium nitrate, calcium nitrate, strontium nitrate and barium nitrate to distilled water and dissolve them so that the cation concentration of each solution for adsorption test becomes 10 ppm. The mixed alkaline earth metal ion solution prepared as above was used as a solution to be treated (hereinafter referred to as a solution to be treated).

(2) Evaluation of adsorptivity A polypropylene centrifuge tube with a sealed stopper having a capacity of 10 ml was added to each of the above 1. (2) Barium adsorbent sample 100 described in
Take mg and add to 2. Solution to be treated 1 described in (1)
0 ml was added and the mixture was shaken in a constant temperature bath at 25 ° C. for 24 hours. The solid-liquid after shaking was centrifuged (10,000 rp.
m. , 10 minutes), and the concentration of each cation (Mg ²⁺ , Ca ²⁺ , Sr ²⁺ , Ba ²⁺ ) in the supernatant was measured by the ICP method, and the concentration difference before and after shaking was calculated by the following formula. The partition coefficient and the separation coefficient were calculated, and the adsorbability of the barium adsorbent sample was evaluated from these values. The partition coefficient Kd is given by Kd = A _i / A _f (ml / g), where A _i and A _f are the adsorbed ion concentration (mg / g) and liquid phase in the solid phase after shaking, respectively. It is the adsorbed ion concentration (mg / ml). As is clear from the above equation, the smaller the A _f value after the reaction, that is, the larger the amount of adsorption to the barium adsorbent sample, the larger the Kd value, and the higher the selectivity. On the other hand, the separation coefficient α which is a measure of the adsorption / separation property between the two cations M1 and M2.
Is given by α ^{M1 / M2} = Kd _M1 / Kd _M2 , and is expressed as a ratio of partition coefficients of M1 and M2 ions. Therefore, the larger the α ^{M1 / M 2} value, the better the adsorption / separation of M1 ions from the M1 and M2 ion coexisting system.

3. Adsorption result 3.1 Adsorption of various precursor compound samples after acid treatment (1) Li₂ MnO₃ System precursor compound sample Li₂ MnO₃ The absorption obtained for the system precursor compound sample
The wearing results are shown in Table 2. Kd value of alkaline earth metal ion
Is Ba²⁺>> Sr²⁺> Ca²⁺, Mg, then water
Ion species having a smaller sum ion radius tend to be larger.
But Sr²⁺ , Ca²⁺And Mg²⁺The Kd value of the ion is
Both are small at 20 ml / g or less,
The difference in selectivity of is not so clear. On the other hand, B
a²⁺The Kd value of ions is significantly higher than that of other ions.
Yes. Therefore, Ba²⁺Separation of ions from other ionic species
Α as a guide^{Ba / Sr, Ca, Mg} The value should be a large number of 2-3 digits.
Shown, Ba from alkaline earth metal ion coexisting system²⁺Io
It is possible to selectively separate the components. On the other hand, the precursor
Compound sample synthesis temperature and Ba²⁺Relation with Kd value of ion
, The Kd value is maximum at the synthesis temperature of 650-750 ℃.
Became.

[0026]

[Table 2]

(2) LiCaMnO ₃ precursor compound sample Table 3 shows the adsorption results obtained for the LiCaMnO ₃ composite oxide sample. The Kd value of the 550 ° C synthetic sample is
It is slightly lower than that of the Li ₂ MnO ₃ precursor compound sample described in 3.1 (1) above, and the Kd is at a synthesis temperature of 750 ° C.
The adsorption results were almost the same as in the case of the Li ₂ MnO ₃ -based precursor compound sample, except that the maximum value was shown in FIG. LiCa
Also in the MnO ₃ -based precursor compound sample, among the alkaline earth metal ions, the Kd of Ba ²⁺ ions was remarkably higher than that of the other ions, and the specific adsorptivity for Ba ²⁺ ions was observed.

[0028]

[Table 3]

(3) LiSrMnO ₃ -based precursor compound sample The adsorption results obtained for the LiSrMnO ₃ -based precursor compound sample are shown in Table 4. The Kd value of the 550 ° C synthetic sample is
Although slightly lower than the Li ₂ MnO ₃ -based precursor compound sample described in 3.1 (1) above, the Kd value was higher than that of the Li ₂ MnO ₃ -based precursor compound sample in all of the samples at a synthesis temperature of 650 ° C. or higher. The maximum was at the synthesis temperature of 750 ° C.
Among them, the increase in the Kd value of Ba ²⁺ ions was more remarkable than that of the other ions, and the α ^{Ba / Sr, Ca, Mg} values were further increased as compared with the case of the LiCaMnO ₃ precursor compound sample. Thus, in the LiSrMnO ₃ -based precursor compound sample, Ba ²⁺
It can be seen that the ion selectivity is further improved.

[0030]

[Table 4]

(4) LiBaMnO ₃ type precursor compound sample Table 5 shows the adsorption results obtained for the LiBaMnO ₃ type precursor compound sample. The Kd value of the 550 ° C synthetic sample is
Although lower than the Li ₂ MnO ₃ -based precursor compound sample described in 3.1 (1) above, the Kd value of each of the samples at a synthesis temperature of 650 ° C. or higher was much higher than that of the Li ₂ MnO ₃ -based precursor compound sample. Showed the maximum value at a synthesis temperature of 750 ° C. The increase of Kd value of Ba ²⁺ ion is more remarkable than that of other ions, and α ^{Ba / Sr, Ca, Mg} values are LiSrMnO
_It was further increased than in the case of the ₃ type precursor compound sample. Thus, in the LiBaMnO ₃ -based precursor compound sample, B
It is clear that the selectivity of a ²⁺ ion is further improved.

[0032]

[Table 5]

3.2 Optimum synthesis temperature of precursor compound sample
And introduced alkaline earth metal ion species and Ba²⁺Aeon selection
Selective adsorption Various precursor compound samples described in 3.1 (1) to (4) above
As is clear from the adsorption results of
Also shows the dependence of Kd on the synthesis temperature.
The maximum value is shown in the synthetic sample, and the optimum synthesis temperature may exist.
I understand. On the other hand, powder X-ray of precursor compound sample after acid treatment
In the diffraction pattern, Li₂ MnO₃ Belonged to
Appears on the high angle side of the strong diffraction peak (d value = 4.75Å)
To the diffraction intensity of the shoulder peak (d value = about 4.6Å)
As for Kd, the same tendency as in the case of Kd was found.
It was These are as follows: 1) Shoulder peak (d)
Value = about 4.6Å)
Being involved in adsorption of ons, 2) Synthesis temperature
As Li rises_(2-X) A_X MnO₃ Increase the amount of
However, since the crystallinity also increases,
Mu or alkaline earth metal ion A²⁺H⁺ Ion substitution is difficult
And the amount of crystalline phase involved in adsorption decreases.
It is presumed to indicate

Table 6 summarizes the introduced alkaline earth metal ion species in the precursor compound sample synthesized at the optimum temperature, their crystal ion radii, and the Kd _Ba and α ^{Ba / Sr} values of the acid-treated sample. As is clear from Table 6, Kd _Ba and α ^{Ba / Sr}
Both are increased by partial substitution of lithium in Li ₂ MnO ₃ with an alkaline earth metal. Further, it can be seen that the larger the size of the introduced metal ion, the greater the effect. In particular, it is clear that the introduction of barium significantly improves the Ba ²⁺ ion selectivity of the acid-treated sample.

[0035]

[Table 6]

[0036]

As described above in detail, the present invention relates to a highly selective barium adsorbent, a method for producing the same, and the like. According to the present invention, 1) Ba ^{2 is} added from an alkaline earth metal ion coexisting solution. ⁺ Ions can be selectively separated and removed,
2) It is possible to provide a new highly selective barium adsorbent that can be applied to a multi-component treated water system containing many kinds of cations. 3) Various high selective barium adsorbents containing Ba ²⁺ ions When brought into contact with the solution to be treated, the surface characteristics of these adsorbents, that is, the ion sieving action of the fine pores formed in the adsorbents, cause the Ba ²⁺ ions to be adsorbed and separated more selectively than in the solution. 4) Therefore, by using this adsorbent, water and various wastewater (harmful wastewater from various mines and industries, radioactive wastewater, etc.) and salt water (ion exchange membrane salt electrolysis plant) can be easily and efficiently used. This enables selective separation of harmful Ba ²⁺ ions dissolved in a trace amount in salt water, etc.) 5) Moreover, this adsorbent is also a kind of solid acid whose surface exhibits acidity, and is used as an acid-base catalyst. It is expected to be used Effect can be exhibited.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hitoshi Mimura             2-17-17 Yonegabukuro, Aoba-ku, Sendai City, Miyagi Prefecture             No. 404 (72) Inventor Takeo Ebina             2-15-1 Nakae, Aoba-ku, Sendai City, Miyagi Prefecture             108 F-term (reference) 4D024 AA04 AA05 AB15 BA05 BC01                       CA01                 4G048 AA04 AA05 AB02 AC08 AE05                 4G066 AA13B AA16B AA26B CA45                       DA07 DA08 FA11 FA37

Claims (5)

[Claims] 1. The general formula Li _(2-x) A _x MnO ₃ (wherein
The value of x is 0 ≦ x ≦ 1, and A represents an alkaline earth metal. ) A highly selective barium adsorbent comprising a hydrogen-type manganese composite oxide obtained by substituting hydrogen for lithium and alkaline earth metal in the precursor composite manganese oxide represented by the formula (1). 2. A general formula _{Li (2-xy) A (} xy) H y MnO
₃ (in the formula, the value of x is 0 ≦ x ≦ 1, the value of y is 0 <y <1, and A and H represent alkaline earth metal and hydrogen, respectively). The highly selective barium adsorbent according to claim 1, which comprises an oxide. 3. The precursor composite manganate according to claim 1.
Acid treatment of lithium and alkaline earth metals in compounds
Substitute with hydrogen for general formula Li_(2-xy) A_(xy) H_y MnO₃
 (Where x is 0 ≦ x ≦ 1, y is 0 <y <1
Yes, A and H represent alkaline earth metal and hydrogen, respectively.
Show. ) Is converted to a hydrogen-type manganese composite oxide represented by
Of high selectivity barium adsorbent characterized by
Law. 4. The high selectivity barium adsorbent according to claim 1 or 2 is brought into contact with a solution to be treated to selectively adsorb and separate Ba ²⁺ ions in the solution to be treated. Barium separation method. 5. A barium adsorption / separation device comprising the Ba ²⁺ ion separation means filled with the highly selective barium adsorbent according to claim 1.