Showing papers in "Clay science in 1988"

Expansion characteristics of montmorillonite and saponite under various relative humidity conditions.

Abstract: The basal spacings of the homoionic (Na+, K+ and Ca2+) montmorillonite (T1) and saponite (SapCa-1) were examined by X-ray powder diffraction (XRD) analysis under the atmospheres of relative humidity (RH). RH was controlled by ReCX (Relative humidity Control system for X-ray diffractometer) precisely in the range of 0 to 100% RH. The variations of basal spacing were almost similar in both minerals at the range of 0 to 80% RH. However, noticeable differences between the hydration state of T1 and SapCa-1 were observed at 100% RH. It was explained that the differences were caused by charge localization and hydroxyl orientation in silicate layer because of these specimens having similar layer charge. In the region between 2 hydration states, irrational and asymmetrical reflections were observed. These reflections indicated interstratified structure of 2 hydration states. Especially at 60% RH, that the segregation structure was recognized. The existence of 2 phases indicates that there is heterogeneity in its charge density of layer.

Phosphate sorption on the clay fraction of kanuma pumice

Abstract: The phosphate sorption product on the clay fraction of Kanuma pumice (KP clay) after air-drying was revealed to be a material close to noncrystalline aluminum phosphate by infrared absorption (IR) spectroscopy. The IR spectrum of phosphate sorbed, obtained by subtracting the diffuse reflectance IR spectrum of KP clay from that of the phosphated KP clay, was close to that of noncrystalline aluminum phosphate. During the phosphate sorption reaction on KP clay, the amount of Clsorption and the concentration of dissolved Al at the initial pH of 4.0 decreased with phosphate sorption. The amount of silicon released, that of Na+ sorption and pH value increased with phosphate sorption. It was concluded that a part of KP clay, a short range order aluminosilicate, was converted to a material close to noncrystalline aluminum phosphate through phosphate sorption and release of silicon.

The distribution of clay minerals in surface sediments of the Okhotsk sea to the South China sea along the Asiatic continent.

Abstract: Surface sediment samples collected from the Okhotsk Sea to the South China Sea along the east Asiatic continent were submitted to clay mineral investigation . Results have shown the distinguishable distribution patterns of clay minerals in the seas and the ocean. The Okhotsk Sea is characterized by the most widespread distribution of smectite. Low concentration of kaolinite is also verified . In the Japan Sea, illite is the most widespread clay mineral, and smectite concentration widely varies from location to location. Kaolinite concentration tends to increase more than that of the Okhotsk Sea. The Pacific sediments along the Japanese Islands are characterized by the high concentration of smectite in the northern part , and of chlorite off the Ku Peninsula and Shikoku. The shallow water sediments from the East China Sea are characterized by the predominance of illite . In the Philippine Sea, the high concentration of smectite is recognized. In the area of the entrance of the Gulf of Thailand to the South China Sea, the high concentration of kaolinite is observed. The results revealed that the distribution of clay minerals in the seas and the ocean along the east Asiatic continent is closely related to the geological and pedological characteristics on the bordering land areas.