Obtenção de argilominerais organofilizados por tensoativo catiônico

Abstract

Clay minerals comprise a versatile class of materials used to design new multifunctional materials, such as new viscosifying additives for oil-based drilling fluids. Organophilization of clays aims to modify their surface to make them compatible with oily and environmentally friendly phases, such as soybean and pine oil. This study looked at the surface modification of clay minerals (bentonite, attapulgite, and palygorskite), evaluating properties such as cation exchange capacity (CEC), specific area, stability in aqueous media, and dispersion in soybean and pine oil. The CEC was determined using the methylene blue adsorption method, with results that showed the highest adsorption capacity for bentonite (85.29 meq 100 g-1 ) compared to atapulgite (35.89 meq 100 g-1 ) and palygorskite (23.86 meq 100 g-1 ). Organophilization was carried out using the cationic surfactant cetyltrimethylammonium bromide (CTAB) and was evaluated by residual surface tension and coverage estimates, which indicated surface modification corresponding to (99.34% for bentonite, 94.23% for attapulgite, and 93.48% for palygorskite). Stability tests showed that the modified clay minerals were hydrophobic, inhibiting dispersion in water. Still, they showed limited compatibility in oils (pine and soybean), with variations in the dispersion index (ID) depending on the concentration of CTAB and the nature of the oil. The results indicate that the structure, surface area, and chemistry of the system directly influence the dispersion behavior and stability of modified systems.