Identification of Expanding Layer Silicates: Layer Charge Vs. Expansion Properties
Prakash B. Malla, Lowell A. Douglas, 1985. "Identification of Expanding Layer Silicates: Layer Charge Vs. Expansion Properties", Proceedings of the International Clay Conference Denver, 1985, Leonard G. Schultz, H. van Olphen, Frederick A. Mumpton
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Layer charges of several reference clays and several soil clays were determined by an alkyl-ammonium ion-exchange technique. The diffentiation of smectite from vermiculite by glycerol or ethylene glycol solvation did not coincide with the layer charges assigned by the nomenclature committee of the Association Internationale pour l’Etude des Argiles (AIPEA). Two-layer ethylene glycol complexes were obtained for clays with layer charge as high as 0.72/(Si, Al)4O10. Two-layer glycerol complexes were obtained for clays with layer charge as high as 0.65/(Si, Al)4O10. Glycerol solvation failed to distinguish between mixtures of minerals and minerals with heterogeneous charge, whereas n-alkylammonium ion exchange distinguished such components.
Saturation of clays with K+ caused the structure to collapse to 11.2–12.8 Å if the layer charge was less than 0.57/(Si, Al)4O10, and to 10–10.6 Å if the layer charge was equal to or greater than 0.63/(Si, Al)4O10. Clays with a double layer of glycerol (18 Å) after K+-saturation and heat treatment at 300°C re-expanded if the layer charge was 0.36 or less. Minerals having layer charges of 0.39 to 0.43 re-expanded with a single layer of glycerol (14 Å). Minerals having layer charges of 0.63 or more failed to re-expand beyond 10 Å, whereas minerals having layer charges between 0.46 and 0.57 expanded and showed two X-ray powder diffraction peaks between 10.0 and 14.0 Å.
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Proceedings of the International Clay Conference Denver, 1985
The papers included in this proceedings volume are representative of the research on clays being conducted in all parts of the world at the time of publication. Many of the subjects treated are controversial, and although some ideas expressed may not necessarily represent the views of the editors, the referees, or the publisher, they deserve to be brought to the attention of the international clay community.