ORGANIC MODIFICATION OF BRAZILIAN SMECTITE CLAY USING DIFFERENT METHODS

Reference	Presenter	Authors (Institution)	Abstract
16-049	Ticiane Sanches Valera	Valera, T.S.(University of São Paulo); Lins, P.G.(University of São Paulo);	The clays of smectite group exhibit a variety of properties that make them interesting to be used in a great range of applications. The replacement of interlayer metallic cations by organic cations, resulting in the organoclays, change the hydrophilic silicate surface into hydrophobic. The surface property changes widen the application field of clays. Organoclays are used as sorbent in pollution prevention and environmental remediation and as rheological additive in paints, greases and cosmetic formulations. The method to change the metallic cations by organic cations has a strong influence on the structure and properties of the clay. A review of the main procedures adopted for the cation exchange reaction reported in the literature was carried out in this work and showed that the studies do not reach a consensus regarding the ideal conditions to prepare an organophilic clay. Therefore, the second objective of this work was to study systematically the structural changes of organically modified smectitic clays by different methods. A Brazilian smectite clay was modified using three different ammonium quaternary salts. The preparation methods included the principal parameters described in the literature: clay particle size, mixing time of clay/water dispersion, mixing time of clay/water/organic cation system, temperature for cation exchange. The organoclays were characterized by X-ray diffraction (XRD), thermogravimetric analyses, and by Foster swelling test. The two most important control parameters in the organoclay preparation method turned out to be the control of the stirring of the water/sodium clay/ammonium salt suspension and the cation exchange temperature, so that a dense pack of salt molecules within the clay structure (detrimental to the adsorption of other organic molecules) could be avoided.
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