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Hydrotalcite-Like Substance, Process for Producing the Same and Method of Immobilizing Hazardous Substance

a technology of hydrotalcite and similarity, applied in the direction of ion-exchangers, nuclear engineering, transportation and packaging, etc., can solve the problem that the conventional ones cannot achieve the desired effect of anionic hazardous substances

Inactive Publication Date: 2008-10-16
WASEDA UNIV +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0007]In view of the above-mentioned problems, it is, therefore, an object of the present invention to provide a hydrotalcite-like substance which ensures so high an anion adsorption effect that ion exchange against a target anion may occur.
[0015]A process for producing a hydrotalcite-like substance of the present invention is characterized in that the method comprises the steps of: mixing an acidic solution containing aluminum ions and magnesium ions with an alkaline solution containing alkalis to produce a hydrotalcite-like substance; and then subjecting the hydrotalcite-like substance thus produced to water removal or neutralization process without ageing.
[0034]According to the hydrotalcite-like substance of the present invention, anion adsorption effect is enhanced and thus ion exchange against target anions can be achieved.
[0035]According to the hydrotalcite-like substance of the present invention, it is possible to produce a hydrotalcite-like substance having a small crystallite size, a large basal spacing, low anion selectivity and thus excellent anion exchange capacity.
[0037]According to the adsorbent of the present invention, anion exchange is allowed to occur between the hydrotalcite-like substance and a target object, thus enabling a hazardous substance to be adsorbed.
[0038]According to the use of the hydrotalcite-like substance for liquid or soil treatment according to the present invention, anion exchange is allowed to occur between the hydrotalcite-like substance and a target object, thus enabling a hazardous substance to be adsorbed and immobilized.

Problems solved by technology

As a result, the conventional ones could not achieve the desired effect in immobilization of anionic hazardous substances.
This is presumably because the highly crystalline hydrotalcite produced by the conventional techniques have such a large crystallite size that the ion exchanging capacity has been deteriorated

Method used

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  • Hydrotalcite-Like Substance, Process for Producing the Same and Method of Immobilizing Hazardous Substance
  • Hydrotalcite-Like Substance, Process for Producing the Same and Method of Immobilizing Hazardous Substance
  • Hydrotalcite-Like Substance, Process for Producing the Same and Method of Immobilizing Hazardous Substance

Examples

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first example

[0047]A hydrotalcite-like substance and a process for producing the same in accordance with an example of the present invention will be explained hereafter. Although temperature is kept at 80 degrees C. or less in all the processes in this example, temperature conditions are not limited thereto, but should just be about 100 degrees C. or lower.

[0048]First, in order to produce a hydrotalcite-like substance of the present invention, an acidic solution containing aluminum ions and magnesium ions are prepared.

[0049]As for an aluminum source of aluminum ions, it is not limited to a specific substance as long as it can generate aluminum ions underwater. For example, alumina, sodium aluminate, aluminum hydroxide, aluminum chloride, aluminum nitrate, bauxite, residue left after producing alumina from bauxite, aluminum sludge, etc. may be used. These aluminum sources may be used either independently or in combination with one or more other sources.

[0050]As for a magnesium source of magnesium...

second example

[0094]Next is a description of a method of immobilizing a hazardous substance using the hydrotalcite-like substance obtained in the foregoing example.

[0095]The hydrotalcite-like substance is used in such a manner that if it is in a slurry form obtained by for example dispersing in water, it is pushed out toward the target object containing a hazardous substance, using a manual or a pressure pump, or others means. Alternatively, the hydrotalcite-like substance that is dried and reduced to powder may be used in such a manner that it is pushed out toward the target object containing a hazardous substance, using a manual or a pressure pump, or others means.

[0096]As described above, the present example of the invention is such that a hydrotalcite-like substance is synthesized by mixing the acidic solution containing aluminum ions and magnesium ions with the alkaline solution containing alkali, and then it is subjected to water removal or neutralization process without ageing; and the hyd...

third example

[0099]The method of immobilizing a hazardous substance in accordance with the third example of the invention proposes pour the acidic solution containing aluminum ions and magnesium ions used in the foregoing examples into a target object while mixing the same with alkali.

[0100]By pouring the acidic solution while mixing it with alkali anions of the hazardous substance can be immobilized due to anion exchange that takes place in the production process of the hydrotalcite-like substance. By immobilizing the anions of the hazardous substance in the production process of the hydrotalcite-like substance thus way, more efficient immobilization of the hazardous substance can be achieved as compared to a case where the hydrotalcite-like substance synthesized beforehand or a powder thereof is added.

[0101]The method according to the present example is applicable to a target object containing hazardous substances, such as soil that has already underwent solidification treatment with cement et...

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Abstract

A hydrotalcite-like substance that is capable of ion exchange with target anions, being of small crystal size and that exhibits large basal spacing, excelling in anion exchange performance; a process for producing the same; and a method of immobilizing hazardous substances. A hydrotalcite-like substance is produced by mixing an acidic solution containing aluminum ions and magnesium ions with an alkaline solution containing an alkali to thereby synthesize a hydrotalcite-like substance, followed by, without ageing, water removal or neutralization. The molar ratio of aluminum ions and magnesium ions is preferably in the range of 1:5 to 1:2. Hazardous substances can be immobilized by pulverizing the hydrotalcite-like substance after synthesis and adding the powder to a subject, or adding a hydrotalcite-like substance in slurry form to a subject, or carrying out addition so as to cause the synthesis directly at the position of the subject. Furthermore, anion adsorption can be performed by a filter containing the hydrotalcite-like substance.

Description

TECHNICAL FIELD[0001]The present invention relates to a hydrotalcite-like substance, a process for producing the same and a method of immobilizing hazardous substance.BACKGROUND ART[0002]Hydrotalcite which is a kind of naturally-occurring layered clay mineral, is mainly comprised of hydroxides of elements that exist naturally abundantly, such as magnesium and aluminum, and the synthesis thereof is capable of being performed comparatively easily. Accordingly, various synthesizing methods have heretofore been disclosed.[0003]For example, a patent document 1 discloses a method of producing a hydrotalcite in a water solvent, using magnesium hydroxide as a source of magnesium, while a patent document 2 discloses a method of allowing magnesium ion to react with aluminum ion in a solution under the presence of alkali.[0004]Moreover, it has been mown that a hydrotalcite has an anion exchange property, and thus it is expected that a hydrotalcite will be able to make a contribution to: water ...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): G21F9/16C01B31/30B09B3/00B09C1/02B09C1/08C01F7/785
CPCB01J20/08B01J20/12B01J20/165B01J20/18B01J41/10B01J2220/42B09B3/0041B09C1/08B82Y30/00C01F7/005C01P2002/22C01P2002/60C01P2002/72C01P2002/78C01P2004/64A62D3/33B01J20/041A62D3/36C01F7/785B09B3/25C01F7/00C01F5/00B09C1/00B09B3/00
Inventor YAMAZAKI, ATSUSHITAKAHASHI, MAI
Owner WASEDA UNIV
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