Influence of temperature on the chemical compositions and microstructural changes of ash formed from palm kernel shell

Abstract

This study investigated the characteristics of raw palm kernel shell (raw PKS) and the influence of temperature variation on palm kernel shell ash (PKSA). The PKSA was obtained under different temperature regimes of 900, 1000, and 1100°C. The characterization of the samples was carried out using X-ray Fluorescence (XRF), Fourier Transform Infrared (FTIR), X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) with attached Energy Dispersive X-ray (EDX) facilities. The results showed that moisture and ash contents and the density of raw PKS were 6.56%, 8.86%, and 745 ​kg/m3, respectively. The colour of the pulverized PKS was dark brown, as observed by visual examination based on standard colour gradation. This colour transformed into various shades of brown when PKS was subjected to different temperature regimes to form PKSA. The XRF analysis showed that silica is the main constituent of the raw PKS and PKSA samples. Silica content in the PKSA increased with the rise in the heating temperature. The FTIR and EDX spectra confirmed the predominance of silicon compounds with functional groups associated with silanol and siloxane. Also, XRD analysis revealed that the silica contents in the samples are quartz, while SEM examinations indicated that temperature increases during processing influenced the microstructure through the reduction of pore concentration in the samples. The silica obtained from the PKSA would find applications in metal matrix composites as partial reinforcing materials.