-A mixed-layer kaolinite/smectite (K/S) containing trace amounts of quartz, discrete kaolinite, goethite-hematite, and calcite was hydrothermally reacted with deionized water at 150", 200", and 250"C for 1 to 12 months. The starting K/S contained 50% smectite consisting of 15~ low-charge and 350 high-charge layers. The X-ray powder diffraction and chemical analyses of the reacted products indic...

-Hydration behavior of Na-smectite crystals synthesized at a pressure of 5.5 GPa and temperatures of 1400"-1500~ was examined by X-ray powder diffraction at various relative humidities (RH) in the range of 0-100%. The basal spacing of the Na-smectite crystal increased stepwise with increase in RH. The reflections observed were only normal reflections of a single or dual hydration states of smec...

Pedogenic smectite from a young (Holocene) tropical soil was reacted in Al-rich solution at 150oC for a range of reaction times (3 to 120 days) in order to study mechanisms and rates associated with the transformation of smectite to kaolinite via interstratified kaolinite-smectite (K-S). As has been observed in tropical soils, the overall reaction rate is logarithmic, with rapid initial transfo...

This study investigates the feasibility of using ethylene oxide (EO) chain adsorption to determine the surface area of smectite in water. Experimental results indicate that high-molecular-weight poly(ethylene oxide) (PEO) should be used to provide reasonable estimations for monolayer capacity of PEO on smectite. The surface areas of smectites in water are calculated from the monolayer capacity ...

Smectite clays demonstrate high affinities for nitroaromatics that strongly depend on the exchangeable cation. The K-smectites have high affinities for nitroaromatics, but Ca-smectites do not. Here we evaluate the ability of K-smectite to attenuate the bioavailability and hence toxicity of 2,4-dinitrotoluene (2,4-DNT) to the aquatic plant duckweed. In the absence of K-smectite, 2,4-DNT was high...

In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit: The temporal evolution of pedogenic Fe–smectite to Fe–kaolin via interstratified kaolin–smectite in a moist tropical soil ch...

The clay and non-clay minerals have been identified by XRD analysis. The non-clay minerals include quartz, crystobalite, orthoclase, microcline, plagioclase, calcite, siderite and dolomite, and the clay minerals include kaolinite (52.39%), illite (36.39%) and illite-smectite mixed layer minerals (11.21%). Kaolinite is the most dominant component in the clay mineral assemblages. The clay mineral...

The adsorption of polymers on clay is important in many applications. However the mechanisms of poly(ethylene oxide) (PEO) adsorption n smectite and its effect on suspension rheology are not well elucidated at present. The aim of this study was to investigate the mechanisms esponsible for PEO sorption on smectite and how this impacts on dispersive behavior of smectite suspension. The results in...

-The chemical compositions ofchlorite-smectite mixed-layered minerals (C/S) from the Ohyu caldera (lnoue, 1985) are analyzed using M+-4Si-3R 2§ diagrams. The assumed original saponite has the following composition: Si3.54Alo.460 ~ 0Alo. ~7~Fe 2§ ~.385Mg1.z95Mn0.o2(OH)2M+o.56. Random C/S minerals ( 100 to 80% expandable layers) are interpreted as an interstratification of the starting 2:1 smecti...

[1] An active seafloor hydrothermal system subjects the background sediments of the Grimsey Graben (Tjörnes Fracture Zone) to alteration that produces dissolution of the primary volcaniclastic matrix and replacement/precipitation of sulfides, sulfates, oxides, oxyhydroxides, carbonates and phyllosilicates. Three types of hydrothermal alteration of the sediment are defined on the basis of the do...