Smectites chemical analyses

Table 5-1. Chemical analysis of two smectites before and after expansitHi with Si02 Ti02 clusters. The difference from 100% is attributed to residual H2P...

During the last 30 years, many other structural models have been proposed for smectites. Each of these models is in complete disagreement with the chemical analysis data and some, likewise, disagrees with the X-ray data. Today, only those models that conform to the H-M-H model are acceptable. 

Samples of the red clay having uniform physical and chemical characteristics were provided by G. R. Heath of the University of Rhode Island. The samples were obtained from core LLUU-GPC-2, collected on October 11, 1976, at 30° 20.9 n, 157° 50.85 w, water depth 5821 meters, and are representative of the smectite-rich region of the red clays which occurs in the sediment at depths below about ten meters. In this region, the sediment appears to contain about five to six percent by weight leachable iron and manganese in the form of hydrous oxides. The remaining material appears to be dominated by iron-rich smectite and lesser, varying amounts of phillipsite (2). The results of a semi-quantitative (precision in data is within a factor of 2) elemental analysis... 

Gougeon, R.D., Reinholdt, M., Delmotte, L., Miehe-Brendle, J., Chezeau, J.M., Le Dred, R., Mar-chal, R., Jeandet, P. (2002). Direct observation of polylysine side-chain interaction with smectites interlayer surfaces through H- A1 heteronuclear correlation NMR spectroscopy. Langmuir, the American Chemical Society Journal of Surfaces and Colloids, 18, 3396-3398 Gougeon, R.D., Soulard, M., Reinholdt, M., Miehe-Brendle, J., Chezeau, J.M., Le Dred, R., Mar-chal, R., Jeandet, P. (2003). Polypeptide adsorption onto a synthetic montmoriUonite A combined solid-state NMR, X-ray diffraction, thermal analysis and N2 adsorption study. Eur. J. Inorg. Chem., 2003, 1366-1372... 

EDS analysis after each wetting and drying cycle does not show any changes in the chemical composition. Because no cations or anions were dissolved in the water, no cation change or dissolution was possible at the temperatures employed in this study. XRD results showed an expansion of the basal spacing as a function of the relative humidity, due to the intercalation of water in the interlayers of the smectite. This effect could not be directly observed in the ESEM images. 

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