Journal of the Clay Science Society of Japan (in Japanese)
Online ISSN : 2186-3563
Print ISSN : 0470-6455
ISSN-L : 0470-6455
Volume 25, Issue 1
Displaying 1-5 of 5 articles from this issue
  • Takuji KANNO
    1985 Volume 25 Issue 1 Pages 1-10
    Published: May 30, 1985
    Released on J-STAGE: September 20, 2011
    JOURNAL FREE ACCESS
    Zeolite was used to various investigation on the application to atomic energy chemistry such as processing of radioactive wastes.
    For the fixation of 85 Kr, zeolite encapsulation method and chemical fixation method has given favorable results concerning 85 Kr loading, but it would be necessary for its practical use to reduce the pressure on encapsulation.
    For the fixation of radioactive nuclides into zeolites from radioactive waste solution, various investigations were performed in many countries. The treatment of large volume of the radioactive waste solution in the Three Mile Iseland atomic power station have been investigated with mixed zeolite of chabazite and zeolite A.
    Various zeolites were also studied on the application to the solidification of 137 Cs and 90 Sr in high level liquid waste by present author. This study was given many favorable results. Cs saturated zeolite A, X and Y were transformed to the mixture of nepheline and pollucite above 1000°C, and mordenite saturated with Cs was also transformed to CsAlSi5012 at 1200°C. These cesium aluminosilicates were very stable. Leaching rates of Cs from the calcined zeolites were decreased with increasing in calcination temperature, and the leaching rate of Cs from zeolites calcined at 1200°C were less than 10-9g/cm2. day which are lower 3 orders than the leaching rate of Cs from boro silicate glass. The volatilization of Cs from zeolite during calcination at high temperature was very little.
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  • Satoru UEDA
    1985 Volume 25 Issue 1 Pages 11-22
    Published: May 30, 1985
    Released on J-STAGE: September 20, 2011
    JOURNAL FREE ACCESS
    Basic researchs for the properties and uses of molecular sieve zeolites are being done extensively in every field of zeolite science, and the properties such as adsorption, molecular sieving, ion exchange and catalysis, which cannot be found in other minerals and inorganic compounds, make possible a variety of industrial applications. These are fundamentally related to the results of synthesis study of zeolites because the zeolite syntheses bring about the exploitation of new type zeolite and play a role as driving force in the discovery of new application.
    In this paper, the syntheses of molecular sieve zeolites under low temperature conditions are described, and the syntheses of high silica zeolites and non-aluminosilicate compounds with zeolite structures are briefly described.
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  • Tatsuaki YASHIMA
    1985 Volume 25 Issue 1 Pages 23-31
    Published: May 30, 1985
    Released on J-STAGE: September 20, 2011
    JOURNAL FREE ACCESS
    The catalysis by zeolites has attracted the attention of many researchers in the fields of chemistry of catalysis and industrial chemistry. The active species can be introduced in the zeolite by means of cation exchange. Zeolite has several physical properties, such as molecular sieving effect and hydrophilic or hydrophobic property. When these properties are composed with catalytic activities, the catalysts with high activity and selectivity can be designed.
    When proton or polyvalent cation is introduced in zeolite by cation exchange method, the solid acidity appears. The acidic zeolites show very high catalytic activity in the reactions which proceed via carbonium ion intermediates. The transition-metal cations can be supported on the zeolite in relatively stable state. Such transition-metal cations show the high catalytic activity as like as the complex or oxide catalysts. When the noble metal cations supported on zeolite are reduced under the suitable conditions, the very small metal crystals can be obtained in the zeolite cage.
    The shape-selective catalysts can be designed by the combination of molecular sieving effect. If most catalytic active sites are inside of zeolite pore, most reactions must be occurred in zeolite pore. Reactant selectivity occurs in the case which only one kind of molecule in the reactant can pass through the pore of zeolite. Product selectivity occurs when only one kind of molecule in the product formed in the pore can go out from the catalyst. In transition state seletivity, certain reactions are prevented because the transition state requires more space than that in the pore of zeolite. For the improvement of the shape-selectivity, (1) the effective pore dimension is more fitted to the molecular dimension of reactant or product, (2) the catalytic activity (ex. solid acidity) are controlled to prevent the undesirable side reactions, and (3) the active sites on the outer surface of zeolite crystal on which the reaction occurs non shape-selectively are poisoned or eliminated.
    Zeolite with the low atomic ratio of silicon to aluminum shows the hydrophilic property. The highly silicious zeolites, however, show the hydrophobic property. So, the acidic highly silicious zeolites can be used in the presence of water as solid acid catalyst.
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  • Masahide OGAWA
    1985 Volume 25 Issue 1 Pages 32-42
    Published: May 30, 1985
    Released on J-STAGE: September 20, 2011
    JOURNAL FREE ACCESS
    Sodium tripolyphosphate has ranked as the most important builder for laundry detergents since about 1955, however, phosphate-containing synthetic detergents have yet been criticized in recent years due to their contribution to the eutrophication of stagnant waters. For such a reason, the phosphate-containing synthetic detergent-one of the causing material of the eutrophication-have been restricted legislatively.
    Many substitutes have been enumerated for detergent builder, Na A type of zeolite has finally been adopted as a phosphate substitute in spite of its water-insoluble pro perty.
    A material for detergent builder has to possess hardwater softening property and alkalinity-giving property to washing water. In such a meaning Na A type of zeolite indicates an excellent ion-exchange capacity and hard water softening property among other zeolites. Further, the zeolites for detergent builder has to possess fine crystallinity, specifically, the mean particle size of zeolite should be smaller than one μM and possess excellent dispersibility, since they wash cloths at low temperature in Japan.
    Such a small mean particle size of zeolite can be obtained by reacting sodium aluminate with activated silica gel from Japanese acid clay treated with mineral acid. And this process is characterized by producing the small mean particle size of zeolite without agglomeration at low cost.
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  • Keizou SUZUKI
    1985 Volume 25 Issue 1 Pages 43-48
    Published: May 30, 1985
    Released on J-STAGE: September 20, 2011
    JOURNAL FREE ACCESS
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