Characterization of silica powder prepared from acid leaching and thermal treatment of RHA

Rice husk is known as one of the popular silica resources. Through the optimum burning condition, such as the combination of appropriate burning temperature and duration of this agricultural waste, rice husk ash (RHA) that contains a high percentage of amorphous silica could be obtained. Therefore, this paper aims to highlight the effect of burning temperature and duration on the content of silica and the colour of the RHA produced, as well as to characterize the properties of white powder obtained from the acid-leached and thermal-treated RHA. The cleaned rice husk was subjected to different burning temperatures in the range of 700°C to 1000°C and different burning duration in the range of 1 hour to 4 hours. These RHA had been characterized through XRF, and the colour of RHA at each parameter had been observed. This study discovered that the optimum burning condition was at 800°C for 4 hours which yielded the whitest powder that contained up to 87.16% of silica. Meanwhile, the powder obtained was characterized by XRD, XRF, FTIR and SEM. High-purity silica powder was obtained by combining acid leaching and thermal treatment of RHA while maintaining its amorphous structure throughout the process. Silica with these properties has high potential and was more in demand in application due to its high reactivity during a reaction.