Hideo Minato

Ca-K exchange reaction and interstratification in montmorillonite

Cation-exchange equilibrium for Ca-K-montmorillonite was studied at 35°, 50°, and 90°C and at three total normalities of the equilibrium solution (0.1, 0.05, and 0.01 N). Changes of the standard free energy for the exchange from K-montmorillonite to Ca-montmorillonite were determined to be −53, −270, and −393 cal/eq at 35°, 50°, and 90°C, respectively. Changes of the standard enthalpy and entropy were 1.7 kcal/eq and 5.6 cal/eq/degree at 35°C, respectively. The sign of the change of the standard free energy was found to be determined mainly by the entropy change, in particular, by the hydration entropy of the cations.The calculation of the excess functions indicates that the mixing model of Ca-K-montmorillonite approximates that of a regular solution. Montmorillonite having potassium equivalent ion fraction of 0.1 to 0.7 consists of a random interstratification of Ca-montmorillonite (15.6 Å) and K-montmorillonite (12.6 Å).РезюмеИзучалось катионно-обменное равновесие для Са-К-монтмориллонита при температурах 35°, 50°, и 90°С и при трех полных нормальностях равновесного раствора (0,1, 0,05, и 0,01 N). Изменения стандартной свободной энергии для обмена от К-монтмориллонита до Са-монтморилло-нита были определены как −53, −270, и −393 кал/эк при 35°, 50°, и 90°С соответственно. Изменения стандартной энтальпии и этропии были соответственно 1,7 ккал/эк и 5,6 кал/эк/градус при 35°С. Было установлено, что знак изменения стандартной свободной энергии определяется в основном изменением энтропии, в особенности гидрационной энтропии катионов.Подсчет остаточных функций показывает, что модель смешивания Са-К-монтмориллонита апроксимирует модель обыкновенного раствора. Монтмориллонит, имеющий калиевую эквивалентную ионную фракцию от 0,1 до 0,7, характеризуется нерегулярным переслаиванием Са-монт-мориллонита (15,6 Å) и К-монтмориллонита (12,6 Å).ResümeeDas Kationenaustausch-Gleichgewicht für Ca-K-Montmorillonit wurde bei 35°, 50°, und 90°C und bei 3 Gesamtnormalitäten der Gleichgewichtslösung (0,1, 0,05, und 0,01 N) untersucht. Die Änderungen der freien Energie beim Austausch von K-Montmorillonit zu Ca-Montmorillonit ergaben Werte von −53, −270, und −399 cal/Äqu bei 35°, 50°, 90°C und bzw. Die Änderungen der Standard-Enthalpie und -Entropie betrugen 1,7 kcal/Äqu bzw. 5,6 cal/Äqu/Grad bei 35°C. Es zeigte sich, daß die Änderung der freien Energie vor allem von der Änderung der Entropie abhängt, insbesondere von der Hydratations-Entropie der Kationen.Die Berechnung der Überschußenergien läßt erkennen, daß das Mischungsmodell für Ca-K-Montmorillonit dem einer regulären Lösung nahekommt. Montmorillonit mit einem Kalium-Ionenanteil von 0,1 bis 0,7 bestehen aus einer ungeordneten Wechsellagerung von Ca-Montmorillonit (15,6 Å) und K-Montmorillonit (12,6 Å).RésuméL’équilibre d’échange de cations pour la montmorillonite Ca-K a été étudié à 35°, 50°, et 90°C et à trois normes totales de la solution d’équilibre (0,1, 0,05, et 0,01 N). Les changements d’énergie libre standard pour l’échange de montmorillonite-K à la montmorillonite-Ca ont été déterminés à −53, −270, et −393 cal/eq à 35°, 50°, et 90°C, respectivement. Les changements de l’enthalpie et de l’entropie standards étaient de 1,7 kcal/eq et 5,6 cal/eq/degré à 35°C, respectivement. On a trouvé que le signe du changement de l’énergie libre standard était déterminé principalement par le changement d’entropie, en particulier, par l’entropie d’hydratation des cations.Le calcul des fonctions en excès indique que le modèle de mélange de montmorillonite-Ca-K est proche de celui d’une solution régulière. La montmorillonite ayant une fraction d’ion d’équivalent de potassium de 0,1 à 0,7 consiste en une interstratification au hasard de montmorillonite-Ca (15,6 Å) et de montmorillonite-K (12,6 Å).

Mode of occurrence and mineralogical properties of clinoptilolite from zeolite tuff in Yashiro-cho area, Hyogo prefecture, especially for the comparison with the specimen for those from Tamatsukuri, Shimane prefecture.

The zeolite tuffs from Lake To jo in “Paleo Setouchi Region” were studied compared with those from Tamatsukuri Hot Spring Area in “Green Tuff Region”. The materials were from Yashiro and Tojo cho, Kato-gun, Hyogo Prefecture. The zeolite tuffs develop in Ogo, Yokawa and Arino formations in Kobe groups of the Miocene age, and are covered by weathered conglomerate of the Alluvial age called Osaka groups. The zeolite tuffs mainly consist of clinoptilolite and contain no mordenite. Purified material and ion-exchanged materials were investigated by means of X-ray diffractometry, chemical and thermal analyses, especially by “Differential Scanning Calorimetry” for the calculations of dehydration energy. It was found that the present zeolite in Lake Tojo are malcrystallized state and are supposed to have been formed in the shallower part than those from Tamatsukuri Hot Spring Area. The present zeolite tuff may have beem formed by the reaction of diageneses of acidic volcanic ash, such as rhyolite and dacite, with thermal water like hot spring in this area.

Deweylite from Horokanai-mura, Hokkaido, Japan

Deweylite, a hydrous magnesium silicate, occurred from serpentine region in Horokanai-mura, Uryu-gun, Hokkaido, and it was yellowish or brownish colour and showed amorphous mass with small druses. Hardness: 2-3. Brittle and with small cracks. Fructure : Conchoidal. Translucent. Luster : vitreous or greasy. Under the microscope, it shows spherulitic texture or granular aggregates and shows amorphous state or weak birefringence. Indices of refraction are lower than 1.54. Decomposed by hydrochloric acid. Chemical analysis of the purified material follows : SiO2 41.62, TiO2 none, Al2O3 0.06, Fe2O3 0.03, FeO 1.35, MnO trace, MgO 33.89, CaO 0.06, H2O (+) 17.60, H2O (-) 6.13, total 100.74% (analysed by H. Minato in 1958). Spectroscopic analysis shows that its trace elements are Mn. Ti and Ni, and V, As, Sb, P, Cu, Zn, Cr and Co are not detected. Weight loss curve of the specimen by means of thermogravimetric analysis is given, also. X-ray powder pattern of the specimen agrees with that from Yagiyama, Fukuoka Prefecture and from Delaware, New York.