Clay Mineralogy

Abstract

The structures of the clay minerals are reasonably well known, but greater detail and more precision are needed if the properties of clays and soils are to be fully understood. For example, the selective adsorptive and catalytic properties and the reaction with organic materials vary with the character of the clay mineral, but the structural factors that control such properties are not well understood. Research is urgently needed on the structure of pure clay minerals and on the reactions of pure clay minerals with organic and inorganic materials. Much past research on clay-mineral reactions has little fundamental value because the clay that was used was composed of a mixture of minerals which were not well characterized. It is not a simple matter to find pure samples of many of the clay minerals, and to a considerable extent progress depends on finding such pure minerals or preparing them in the laboratory.

Uranyl–chlorite sorption/desorption: Evaluation of different U(VI) sequestration processes

“…After all reactions were added to the surface complexation model, the more general goodness-of-fit parameter R 2 was used to compare the modeled versus measured U(VI) sorption loadings under different conditions. The total number of surface hydroxyl sites is calculated from an estimate of the site density of [M(O,OH) 6 ] octahedral sites, where M is a metal ion such as Mg 2+ , Fe 2+ , Fe 3+ or Al 3+ , on the edges of chlorite (Grim, 1962). Reactive site density for chlorite was estimated to be 4.65 sites nm À2 , based on accessible surface sites per chlorite unit cell edges, including every other edge site on both the octahedral layer between tetrahedral sheets as well as the extra ''brucite-like" octahedral layer and excluding basal surface sites, which are known to be relatively unreactive to divalent aqueous metal ions (e.g., O'Day et al, 1994).…”

Cation-controlled wetting properties of vermiculite membranes and its promise for fouling resistant oil–water separation

“…Clays are one of the best examples of such systems 5 . Owing to their unique properties such as high capillarity, degree of swelling 6 , and exceptional thermal and chemical stability, they are widely used in sectors ranging from cosmetics, medicine, agriculture, oil and gas industries, environmental remediation and construction engineering [6][7][8] .…”

Influence of Clay Content and Suction on the Strength of Compressed Earth Blocks

“…The degree of crystal perfection of the kaolinite affects its physical properties. The superficial charge of the kaolinite particles is very small due to little or no isomorphic substitution, broken bonds along the particle edges being principal place of electric charge concentration [34]. This combined with a relatively low surface area (8-15 m 2 /g) explains kaolinite's low absorption and adsorbtion characteristics.…”

“…This accounts for charge deficiency which is balanced by exchangeable cations adsorbed between the unit layers and on the particle edges. Substitution within the lattice is reported to cause about 80% of the total cation exchange capacity [34]. If the octahedral positions are mainly filled by aluminum, the smectite mineral is beidellite; if filled by magnesium, the mineral is saponite; and if by iron, the mineral is nontronite.…”