On surface of micropores and fractal dimension of activated carbon determined on the basis of adsorption and SAXS investigations

Granulated commercial activated carbon obtained from hardcoal was separated for fractions, by elutriation, in an air stream of constant Bow-rate. Three samples of different fall down distances from the outlet tube were demineralized. Benzene adsorption isotherms were determined at 293 K and SAXS measurements were performed for each one. The Dubinin-Izotova and Dubinin-Stoeckli equations were used for evaluation of micropore structural parameters of examined carbon samples. On the basis of these equations different methods of calculation of geometric surface area were discussed. Obtained results were compared with values evaluated by using the method proposed hare. This method comprises results of SAXS and adsorption measurements. Changes of geometric surface area were confirmed by analysis of surface roughness measured by fractal dimension. The values of fractal dimension were obtained by method of calculation on the basis of adsorption data proposed previously by Ehrburger-Dolle and were compared with modification proposed here. This modification is based on well known correlation given by McEnaney. Obtained values of fractal dimension were compared with values determined on the basis of SAXS data. (C) 2000 Elsevier Science Ltd. All rights reserved.