巻号一覧
33 巻 (1993 - 1994)
- 4 号 p. 181-
- 3 号 p. 130-
- 2 号 p. 59-
- 1 号 p. 3-
33 巻, 4 号
選択された号の論文の8件中1～8を表示しています
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佐藤 満雄1994 年 33 巻 4 号 p. 181-185
発行日: 1994/03/25
公開日: 2011/09/20
ジャーナル フリーA mathematical representation of structures of both interstratified minerals and zeolites, which are all main components constituting clays, is reviewed in the special refbrence to the connectivity of their component layers and atoms. The order-disorder arrangement of interstratified minerals can be charactehzed by one dimensional connectivity between the layers in the 1st, 2nd, 3rd, ...nth neighbor. Their relationships can be simplified in terms of the concept of Markov chain in the stochastic process, and represented on an interstratified structure diagram. Three dimensional zeolite frameworks can be characterized with a concept of concentric clusters, in which the connectivity relation between the framework T (Si, Al) atoms in the 1st, 2nd, 3rd, ...nth distance (nighbor) is realized on the number and valence of front nodes. The concept also serves for the characterization of Si, Al distribution on the framework and derivation of expected frequencies of Si, Al substituted clusters. Their frequencies against different Si/Al ratio are not continuous, but discontinuous at three points of Si/Al=1.3, 2.0 and 4.0. The points are fkirly correlated with the turning points of physical and chemical properties ever reported.
It is noteworthy that both structural characteristics are realized on the mathematical representation of the connectivity relations in the consecutive neighbors.抄録全体を表示PDF形式でダウンロード (640K) -
福嶋 喜章, 山崎 淳司1994 年 33 巻 4 号 p. 186-192
発行日: 1994/03/25
公開日: 2011/09/20
ジャーナル フリーGeological situations of main sepiolite deposits in sedimentary basins in Turkey, Spain, Nevada, USA, and Hunan-Jianxi, China, were reviewed.
Although the deposit in China is found in lower Permian sedimentary basin, other deposits are in Tbrtiary or Quaternary series. Sepiolite in these basins was believed to be generated in palustine, shallow lacustrine or playa, which were formed during the last part of drying Process of Mg-rich and high pH lakesor seas.
Sepiolite seams were observed in transition range between carbonates sediments and tuff, arkoses, or volcanic ash regions, from which Si was supplied. A structure of silica in condensed aqueous environments at the transition range would be one of the key points of sepiolite genesis.抄録全体を表示PDF形式でダウンロード (10895K) -
伊藤 雅和1994 年 33 巻 4 号 p. 193-201
発行日: 1994/03/25
公開日: 2011/09/20
ジャーナル フリーRecent development of application in the fields of 1) Foundry, 2) Civil engineering (largest markets), 3) Cat litter (new market) and 4) Radioactive waste disposal (future market) were reviewed.
1) Foundry market: The properties for mix bentonite were evaluated and indicated that Na type bentonite has high thermal stability, but less compressive strength. While Na exchanged bentonite possess the renew properties, with high compressive strength, but low thermal stability. According to the bentonite properties, molding sand for impact molding system are different from usual system. The composition of mix bentonite for each foundry use are further disscussed in the text.
2) Civil engineering market: New process in recycling waste mud by flocculation was succesfully developed.
3) Cat litter market: Cat litter is now becoming a valuable product.
4) Radioactive waste disposal: Various studies of bentonite were made in this field through natural analogue technic.抄録全体を表示PDF形式でダウンロード (4739K) -
宮脇 律郎1994 年 33 巻 4 号 p. 202-214
発行日: 1994/03/25
公開日: 2011/09/20
ジャーナル フリーRecent studies on the hydrothermal synthesis of kaolinite, particularly the results of the Special Research Program for Important Regional Technology, AIST, MITI, on the “Synthesis Technology of Artificial Clay for High Performance Ceramics”, are hereby introduced and reviewed. The formation of kaolinite depends on the structure of raw material, as well as the chemical composition of reaction system, pH of the system, temperature, reaction period, and some other factors that would greatly influence its formation. These factors are complicatedly related to each other, however they are very important conditions of the synthesis. Amorphous intermediate phases were found in at least two cases of the reaction processes of kaolinitization. The presence of the intermediate phases and the dependence of kaolinite formation on the structure of raw material suggest that molecular-clusters consisting of polycondensed SiO4 tetrahedra are the minimum units in the reaction mechanism of kaolinitization.抄録全体を表示PDF形式でダウンロード (1893K) -
ガス吸着特性と粒子の分散小菅 勝典1994 年 33 巻 4 号 p. 215-222
発行日: 1994/03/25
公開日: 2011/09/20
ジャーナル フリーLayered polysilicates consist of silica as a major constituent with alkali ions and water molecules. Magadiite and kenyaite, which are well-known compounds of layered polysilicates, and their silicic acids have been noted as host materials for intercalation and ion-exchange. However, detailed crystal structure and ion-exchange properties of these compounds have not been clarified. They carry silanol group on internal surface and exhibit ion selectivity of H+>Na+>Li+>K+. Furthermore, they have micropore “8-membered ring” built up with SiO4-tetrahedra layers and no Al in the framework. From above points of view, these compounds show different properties from clay minerals and are therefore expected to provide new materials.
Particular attention is directed to the potential of these compounds for applications relating to their properties such as thermal stability based on dehydration and rehydration, dispersion of the particles and gas adsorption. An idea to prepare porous materials from layered polysilicates by intercalation is also considered.抄録全体を表示PDF形式でダウンロード (3223K) -
松枝 直人1994 年 33 巻 4 号 p. 223-232
発行日: 1994/03/25
公開日: 2011/09/20
ジャーナル フリーMolecular orbital method can predict the physico-chemical properties and structure of a molecule. The predictions are made by theoretical calculations based on quantum mechanics. Recent developments using computer hard and softwares enable the application of the method to clay minerals. In the input file, some key words are necessary beside the geometrical data of minerals to subsequently complete calculations automatically.
Charge distributions of 2:1 type layer silicate minerals were calculated by the molecular orbital method using model clusters. Results showed that the charge on surface oxygen atom did not change following isomorphous substitutions. The molecular orbital method has interpreted the observed relationship between Si/Al ratio and surface acid strength of allophane. It showed that the interaction between silanol group of polymerized silicic acid and the pore moiety of the wall enhanced the degree of dissociation of the silanol group.
The molecular orbital method allows us to understand the properties of clay minerals on the basis of electronic states. The studies of clay minerals are expected to develop further by utilizing this theoretical method.抄録全体を表示PDF形式でダウンロード (1272K) -
山岸 晧彦, 堀田 裕司1994 年 33 巻 4 号 p. 233-245
発行日: 1994/03/25
公開日: 2011/09/20
ジャーナル フリーThis article reviews the recent works on the application of clay thin films as an electrode modifier. This describes the fundamental mechanisms of a clay-modified electrode as well as the attempts to elucidate various kinds of functional electrodes. A clay-modified electrode is prepared by covering an electrode (e.g. glassy carbon, SnO2 glass and platinum) with a thin film of clay (<1μm in thickness). When a metal complex is included in the film, the electrode shows reversible redox currents in cyclic voltammetry due to the metal complex. The electrochemical studies also revealed that metal complex in a particular binding state like an ion-paired species diffusing in a clay film to an electrode surface wherein the complex exchanges an electron. Based on the methods, various kinds of functional electrodes have been constructed to achieve asymmetric electrochemical syntheses, ion-selective electrodes and photo-sensitive diodes. New attempts are described to construct a clay film controlled on a molecular scale and to study the mass transfer through the film with the quartz crystal balance methods.抄録全体を表示PDF形式でダウンロード (1454K) -
前田 雅喜, 刀根 如人, 芝崎 靖雄1994 年 33 巻 4 号 p. 246-251
発行日: 1994/03/25
公開日: 2011/09/20
ジャーナル フリーThe water vapor adsorption and desorption on various kaolinitic clays were studied. The adsorption isotherms showed a multi-layer adsorption (type II isotherm) but hysteresis was not observed under the present measurement conditions. The order of the water film thickness, calculated from the water vapor adsorption isotherms, is Motoyama Kibushi Clay≥Jinya Kibushi Clay=Motoyama Gairome Clay> Hara Gairome Clay>Georgia Kaolin>Kanpaku Kaolin in the range of relative humidity from 10 to 90% at 40°C. This order corresponds to the order of plasticities well known from experience. It was found that the water film thickness of weathering-origin clays was thicker than that of hydrothermal-origin clays. The difference is considered to be due to the different amounts of adsorbed cations on the kaolinitic clay surface.抄録全体を表示PDF形式でダウンロード (748K)
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