Surface fractal dimension of graphitized carbon black particles

Fractal analysis of adsorption isotherms is used to study the surface roughness of carbon blacks graphitized at 3000 K. Gases of various molecular sizes (nitrogen, argon, ethane, propane, and butane) are adsorbed on different grades of carbon black. Using the molecular yardstick method, it is found that the surface fractal dimension of graphitized carbon black is 2.0+/-0.1 and is independent of carbon black grade. Another approach, the FHH method, was also used. But the slopes of the FHH plots are sensitive to the forces responsible for adsorption and thus they cannot give the fractal dimension of carbon blacks. Direct imaging of surface structure of carbon black particles carried out using atomic force microscopy (AFM) confirmed that the surface of graphitized carbon black particles exhibits a low degree of irregularity on the atomic scale.