Organoclays obtained from bentonite

Full text: Modification of clays using organic compounds has become important for many applications in environmental areas, enabling their use for pollution control of some types of aqueous effluents [1,2]. In the present work, sodium bentonite clays mineral was modified at room temperature by a dry process using different amounts of the hexadecyl trimethyl ammonium salt (commercial name Sunquart – CTAC 50). The organoclays were characterized by thermogravimetry (TG/DTG), X-ray diffraction (XRD), infrared spectroscopy (FTIR), adsorption/desorption nitrogen measurements, X-ray fluorescence (XRF), scanning electron microscopy (SEM) and Foster swelling. Thermogravimetric analysis showed that the modified clay showed a mass loss between 23 and 137 °C assigned to the loss of adsorbed water and a second mass loss event from 137 to 390 °C due to the decomposition of the surfactant. The XRD patterns confirmed the presence of montmorillonite and impurities, such as quartz and other mineralogical species. The infrared spectrum showed absorption bands characteristic of the natural chemically modified sodium montmorillonites. The BET surface area value was 43.4 m² /g^-1 for natural sodium montmorillonite and the values were decreased to 5.2 - 6.0 m² /g^-1 for the modified montmorillonites with different cation exchange capacity. In the XRF analysis, typical chemical composition of the smectite clays mineral was observed. The SEM micrographs showed plates morphology, which is characteristic of clay minerals. In Foster swelling experiments, without stirring, montmorillonites showed hydrophobic character while the pristine sample swelled, indicating the high potential of the modified solids for use as adsorbents. References: [1]. Mousavi, S. M.; et. al.; J. Sci. Tech.; 30, (2006), 613-619; [2]. Lee, S. M.; et. al.; Appl. Clay Sci.; 59-60, (2012), 84-102.(author)