Abstract

VARGAS-RODRIGUEZ, Yolanda Marina et al. Spectroscopic, chemical and morphological characterization and superficial properties of a Mexican montmorillonite. Rev. mex. cienc. geol [online]. 2008, vol.25, n.1, pp.135-144. ISSN 2007-2902.

The characterization by means of spectroscopic techniques of a natural montmorillonite collected at Cuencamé, Durango is described. The composition of the tetrahedral and octahedral layers was analyzed by magic angle spinning Nuclear Magnetic Resonance (NMR) for the nuclei of ²⁹Si and ²⁷Al. The superficial properties of the clay were quantified using the technique of adsorption-desorption of nitrogen as well as the Brunahuer-Emmett-Teller (BET) and Barrett-Joyner-Halenda (BJH) methods. The results indicate that the analyzed clay is a Na-montmorillonite with a molecular layer of water adsorbed between their laminae, where the Si atoms in the phyllosilicate Q³ structure display different composition of Si-nAl (n = 0, 1 and 2). About 3.3% of the Al atoms in the structure are replacing Si atoms in the layer. The presence of the paramagnetic Fe⁺³ and Mn ⁺² ions in the structure was determined by electronic paramagnetic resonance after the analysis of the acidified clay treated with HCl and CF₃SO₃H. Additionally, the results acquired by atomic absorption, scanning electron microscopy, infrared and gravimetric thermal analysis are discussed.

Keywords : clay; montmorillonite; magic angle spinning (MAS); Nuclear Magnetic Resonance (NMR); ²⁹Si; ²⁷Al; electronic paramagnetic resonance; X-ray diffraction; thermal analysis.

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