Electrostatic attraction, clay

Most particulate matter in the ocean, such as clay minerals, metal oxyhydroxides, and POM, possess a small net negative charge at the pH of seawater. Hence, metal cations are electrostatically attracted to the particle surfaces. As shown in Figure 11.6, these... 

This intercept in this fitted result implies that the alkyl ammonium ions experienced an electrostatic attraction to the clay surface corresponding to ... 

Individual particles of clay minerals consist of stacks of layers, which in some systems are separated by interlayer materials. The individual layers are held together by secondary forces (i.e. van der Waals attractive forces, hydrogen bonding or weak electrostatic attraction). 

Like calcium, strontium has moderate mobility in soils and sediments, and sorbs moderately to metal oxides and clays (Hayes and Traina 1998). The Sr2- ion is strongly hydrated and is firmly coordinated with six or more water molecules in aqueous solution. When Sr2- ions sorb on negatively charged mineral surface sites, the hydration sphere is retained (O Day et al. 2000). Strontium sorbs as hydrated ions on the surface of clay minerals (kaolinite), weathered minerals (amorphous silica), and iron oxides (Sahai et al. 2000). Sorbed carbonate on iron oxides enhances the sorption of Sr2- and permits the nucleation of Sr2- as strontium carbonate (Sahai et al. 2000). On calcite (calcium carbonate), Sr2 sorption occurs by electrostatic attraction as hydrated ions. However, at higher concentrations, precipitation of strontianite (strontium carbonate) occurs and strontium is likely to be less mobile (Parkman et al. 1998). 

Class C—emulsions of various organic substances, increasing the electrostatic attraction and introducing ultra-fine particles to cement paste. The following compounds, among many others, are in this group acryl emulsions and water dispersions of clay. 

Students may believe that sediments become hard rocks simply by being compacted together. This is only the case with fine-grained sediments, such as clays, where electrostatic attraction helps to hold the particles together. Sands and coarser-grained sediments require some form of natural cement to bind the particles together. Ask a student to take a handful of sand and see if it is possible to make a rock by squeezing it as hard as possible. They will find that they cannot do it. 

Exfoliated clay nanocomposites formed between organocation exchanged montmorillonites and thermoplastic Nylon-6 have recently been described by Toyota researchers (9-11). Clay exfoliation in the Nylon-6 matrix gave rise to greatly improved mechanical, thermal and rheological properties, mal g possible new materials applications of this polymer. However, it is relatively difficult to achieve complete exfoliation of smectite clays into a continuous polymer matrix, because of the strong electrostatic attraction between the silicate layers and the intergallery cations. 

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