Journal ArticleDOI
Analysis and Implications of the Edge Structure of Dioctahedral Phyllosilicates
G. Norman White,L. W. Zelazny +1 more
TLDR
In this article, the edge charge of lath-shaped illite has been analyzed and it has been shown that the apparent deficient occupancy of the octahedral sheet, presence of excess water, and measurable cation exchange capacity may in part be the result of a large ratio of edge area to total volume, with no other chemical or structural change in the mica layers.Abstract:
Crystal growth theory was applied to describe edge sites of phyllosilicates. Three face config- urations were found to exist. One face has one tetrahedral site per tetrahedral sheet and two octahedral one-coordinated sites per crystallographic area ac sin/3, where a and c are layer dimensions and/3 is the angle between them. The other two faces are similar except that they have one less octahedral site which is replaced by one Si'v-O-A1 vt site in this same ac sin/3 area. A transfer of bonding energy from the remaining octahedral site to the Si'v-O-A1 w site is believed to neutralize all edge charge on faces containing these latter sites at normally encountered pHs (pH 3-9). A similar charge rearrangement along the edges results in an apparent decrease in the permanent charge of the mineral with an increase in edge area. On the basis of such an analysis, lath-shaped illite can be described as a very fine grained dioctahedral mica in which the apparent deficient occupancy of the octahedral sheet, presence of excess water, and measurable cation-exchange capacity may in part be the result of a large ratio of edge area to total volume, with no other chemical or structural change in the mica layers. The increasing importance of edge charge relative to layer charge produces erroneous formulae for 2:1 phyllosilicates in very fine grained samples containing fewer than 2 of 3 octahedral sites occupied by cations, on the basis of a 22-charge half cell.read more
Citations
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Journal ArticleDOI
Preparation and catalytic properties of cationic and anionic clays
TL;DR: In this paper, the structure, main properties and preparation methods of cationic and anionic clays are reviewed in light of the versatility and potential of these materials, which may be useful tools in the move towards establishing environmentally friendly technologies.
Journal ArticleDOI
The Use of XAFS to Distinguish between Inner- and Outer-Sphere Lead Adsorption Complexes on Montmorillonite.
TL;DR: Important information is revealed on Pb sorption behavior on clays and insights are provided into the use of XAFS to determine sorption mechanisms.
Journal ArticleDOI
The Influence of Uranyl Hydrolysis and Multiple Site-Binding Reactions on Adsorption of U(VI) to Montmorillonite
TL;DR: In this article, a site-binding model was applied that treated SWy-1 as an aggregate of fixed-charge sites and edge sites analogous to gibbsite and silica, and results were modeled to identify likely surface complexation reactions responsible for removal ofuranyl from solution.
Journal ArticleDOI
Surface-charge properties and UO22+ adsorption of a subsurface smectite
TL;DR: In this paper, surface charge and UO22+ adsorption were measured on a clay-sized, subsurface mineral isolate whose mineralogy was dominated by a ferrogenous beidellite.
Journal ArticleDOI
Electron transfer at the mineral/water interface: Selenium reduction by ferrous iron sorbed on clay
Laurent Charlet,Andreas C. Scheinost,Christophe Tournassat,Jean-Marc Greneche,Antoine Géhin,Alejandro Fernandez-Martinez,S. Coudert,Delphine Tisserand,Jocelyne Brendle +8 more
TL;DR: In this article, the authors investigated the long-term kinetics of selenite ( Se(IV)O 3 - ) sorption to montmorillonite in the presence of Fe2+ under anoxic conditions.
References
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Book
The chemistry of clay minerals
Charles E. Weaver,Lin D. Pollard +1 more
TL;DR: Rich as mentioned in this paper discusses the relationship of composition to structure of layer silicates of clay and the relationship between weathering and electrochemica reactions to a smal degree in a series of books called "Developments in Sedimentology".
Journal ArticleDOI
Interstratified Clays as Fundamental Particles
TL;DR: Transmission electron microscopy and x-rays diffraction demonstrate that the x-ray diffraction characteristics of a wide range of interstratification can be modeled experimentally by utilizing materials containing only three types of particles.