Analysis of surface topography of ash particles obtained from sludge combustion using tapping-mode AFM

Abstract

Analysis of ash particles obtained after the thermal treatment of pulp and paper sludge has been carried out by atomic force microscopy (AFM) to establish their surface topography. Results were compared to those obtained on ash particles prepared by thermal treatment of a simulated ash pellet prepared by using synthetic oxides. The AFM images of the simulated ash showed a rigid glassy pellet with smooth continuous non-porous outer surface with a vertical surface variation of about 0.7 nm. The real ash was also found to have a continuous, non-porous and relatively smooth outer surface (vertical surface variation is 14.3 nm). The results obtained by AFM as well as SEM and X-ray diffraction (XRD) indicate that the major surface topographic features of both the real and the simulated ash are similar. On the basis of these results, it is suggested that the simulated ash could be used to examine the selected characteristics of the real ash. Simulated ash analysis may also help to solve problems associated with parallel AAS, ICP-AES and XRD analyses of the real ash, since it is usually difficult to generate enough of the ash material for these analyses.