Surface analyses of pyrolysed rice husk using scanning force microscopy

Abstract

Scanning force microscopy (SFM), also referred to as atomic force microscopy (AFM), has been used for the surface characterization of untreated and pyrolysed rice husk samples. This technique, unlike scanning electron microscopy, provides both qualitative and quantitative measurements. The principles of SFM and sample preparation are discussed. Quantitative data in the form of surface roughness, void and fractal dimension are presented. The rice husks were pyrolysed in air at 573, 673 and 773 K for 30 min in a muffle furnace. The surfaces of the rice husk pyrolysed at 773 K showed voids due to the decomposition of the organic matter. Quantitative analysis of these samples indicated that the surface roughness parameters decreased with increasing temperature owing to the increased decomposition of the organic matter. In addition, the number of voids and their z dimensions increased with increasing temperature. The fractal dimension increased from 2.12 to 2.31 with increasing temperature, indicating that the voids were becoming rougher. Furthermore, the decomposition of the materials followed a fractal geometry.