Fractal approach of activated carbons from solid waste materials

Carbonaceous composite materials were produced from various pyrolyzed organic waste materials by steam activation. Fractal dimensions derived from SAXS and adsorption measurements were used to explain the changes in the matrix and the surface microstructure, due to the activation. The comparison of the fractal dimensions from SAXS and nitrogen adsorption data can be successfully applied to understand the development of the porous structure. In these materials, of heterogeneous matrix, no correlation was found between the B.E.T. specific surface area and the fractal dimensions derived from various methods. The adsorption of different substrates is disturbed by the chemical heterogeneity of the surface. In these cases, the applicability of aqueous solutions in the description of the surface geometry might be questioned. (C) 1998 Elsevier Science B.V.