The free-radical polymerization of acrylamide in aqueous clay dispersions and the structure of the resulting polymer-clay nanocomposite hydrogels have been investigated by rheometry using oscillatory deformation tests. Laponite was used as clay particles in the hydrogel preparation. The reactions were carried out with and without the presence of the chemical cross-linker N,N′-methylenebis(acryl...

A new approach was developed for reducing leaching of herbicides and contamination of groundwater. Liposome-clay formulations of the anionic herbicides sulfometuron and sulfosulfuron were designed for slow release by incorporating the herbicide in positively charged vesicles of didodecyldimethylammonium (DDAB), which were adsorbed on the negatively charged clay, montmorillonite. Freeze fracture...

Clay minerals are layer type aluminosilicates that figure in terrestrial biogeochemical cycles, in the buffering capacity of the oceans, and in the containment of toxic waste materials. They are also used as lubricants in petroleum extraction and as industrial catalysts for the synthesis of many organic compounds. These applications derive fundamentally from the colloidal size and permanent str...

Ichthyoliths—microfossil fish teeth and shark dermal scales (denticles)—are found in nearly all marine sediments. Their small size and relative rarity compared to other microfossil groups means that they have been largely ignored by the paleontology and paleoceanography communities, except as carriers of certain isotopic systems. Yet, when properly concentrated, ichthyoliths are sufficiently ab...

In many environments a large portion of particulate material is contained in aggregated particles; however, there is no validated framework to describe how aggregates in the ocean scatter light. Here we present the results of two experiments aiming to expose the role that aggregation plays in determining particle light scattering properties, especially in sediment-dominated coastal waters. Firs...

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Expansive soils owe their characteristics to the presence of swelling clay minerals. As they get wet, the clay minerals absorb water molecules and expand; conversely, as they dry they shrink, leaving large voids in the soil. Swelling clays can control the behavior of virtually any type of soil if the percentage of clay is more than about 5 percent by weight. Soils with smectite clay minerals, s...

The role of modified clay has been employed in many areas of engineering research. Structure of clay was mainly focused on alumino-silicate layer and its form was presented as pillar layer. It composed of many ion exchanges inside. In industry, in order to use clay with higher efficiency, modification on surface and porosity has been developed. CTAB, one of the most effective cationic surfactan...