Modificação superficial de bentonita sódica para obtenção de argila organofílica.

Abstract

In the literature some methods for obtaining organophilic clay, but are not yet consolidated the synthesis parameters. In this study, aiming the knowledge of the influence of synthesis parameters in organophilization process, a bentonite clay naturally sodium was modified superficially through reaction of cation exchange using different parameters of agitation time (20, 60 and 120 min), rest time (0, 12, 24, 36 and 48h) and concentration surfactant (100, 150 and 200% CEC). The organophilic clays obtained were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), particle size by laser diffraction and Foster swelling tests in water and hexane. Analyses of DRX allowed to verify that the stirring time and the standing time showed no effect on basal spacing of the obtained organoclays, with influences only of the surfactant concentration. FTIR analysis confirmed the presence of surfactant in organoclay by characteristic peaks, indicating that modification of the bentonite has occurred. The particle size distribution of the analyzed organoclays showed that its particles are in the micrometer range and that they are influenced by the surfactant concentration and other parameters slightly. Foster swelling test showed the organophilic character of obtained clays. The results were compared with those of a commercial organoclay, Cloisite® 15A, allowing verification that the organophilic clays obtained have higher interplanar spacing d001 and greater swelling in hexane (with and without agitation). The use of water as solvent in Foster swelling test showed that the commercial organophilic clay is totally hydrophobic, which is not observed in the obtained clay, suggesting that a small fraction of clay remained in the sodium form or have been partially covered by the surfactant. Overall, the results obtained showed the intercalation of surfactant between the lamellae of bentonite, low influence of agitation time parameters and rest time in the obtained basal spacing and the influence of the rest of time with respect to the degree of hydrophobicity checking that a greater rest time is more efficient organophilization process. The parameters needed to obtain a organoclay with higher basal interplanar distance and greater hydrophobicity were the concentration of 150% of CEC, 20 minutes of stirring and 36 hours of rest.