Preparation and characterization of carbon/montmorillonite composites and nanocomposites from waste bleaching sodium montmorillonite clay

Waste bleaching sodium montmorillonite clay was used to prepare carbon/clay nanocomposites and composites by calcination in a reducing atmosphere. The main purpose of this study was to determine the influence of the calcination temperature and solvent washing in the material structure and its adsorption properties. X-ray diffraction patterns detected the nanocomposite formation only in the samples calcinated at 350 °C, whose structures were also described by Fourier transform infrared spectra. SEM images showed that all the samples were composed of various agglutinated grains and the non-washed sample calcinated at 350 °C presented the highest carbon recovery as its surface was the smoothest one, as confirmed by thermogravimetry curve. As a result of this higher carbon content, its methylene blue and gasoline adsorption capacities were the highest, albeit a bit lower in comparison to activated carbon due to the hydrocarbon formation onto sample surface. Finally, BET and BJH studies showed that porosity should also be improved in order to achieve higher adsorption values.