Estudo do processo de organofilização de uma argila proveniente da região sudoeste do estado de São Paulo

Abstract

The clay minerals are materials widely distributed in Earth’s crust, are materials of diverse properties and applications, besides these relevant characteristics, the clay minerals are cheap materials. Through purification processes and specific treatments, the properties of clay minerals can be altered by amplifying and diversifying their spectrum of applications. Among these processes, the organophilization gives the modified clay hydrophobic properties, so organophilic clays can be applied in the treatment of industrial effluents, in production of nanocomposites, in pharmaceutical industry among other applications. The objective of the present work was to study the organophilization process in a clay mineral from southwest region of the state of São Paulo. In this work, two concentrations of the surfactant cetyltrimethylammonium bromide (CTAB) were investigated: above and below its critical micellar concentration (CMC). Molecular Spectroscopy in infrared region (FTIR) was realized to evaluate the changes in the bonds present in the clay minerals due to the organophilization process. The morphology of the materials was investigated by scanning electron microscopy (SEM), and the images showed that the morphological aspect of the materials remains after the organophilization process. Dispersive energy spectroscopy (EDS) was also investigated and elemental analysis indicated the presence of the carbon element in the organophilized clays. All results indicated that the clay mineral under study presented a hydrophobic character after the organophilization process. The hydrophobic behavior of the organophilized clays was also evidenced when they were placed in contact with water, because only by visual inspection it was evident the change of hydrophilic to hydrophobic behavior of clays after the organophilization process. No less relevant, photographic images showed a remarkable change in the contact angle of organophilic clays in relation to sodium and in natura clays. It was observed from images that in the CTAB concentration below its critical micellar concentration presented a larger contact angle, that is, a material of greater hydrophobicity was obtained in this condition investigated.