Physical, chemical and electric characterization of thermally treated rice husk ash and its potential application as ceramic raw material

Abstract

Rice husk ash (RHA) is composed essentially by carbon and high levels of silica that justify the economically viable use of RHA in production of ceramic materials. Therefore, this study presents the physical, chemical, and electric characterization of two RHAs submitted to thermal treatment at different temperatures. Grain size, specific weight, specific surface area, total carbon analysis as well as X-ray fluorescence spectrometry, scanning electron microscopy, X-ray diffraction, and complex impedance spectroscopy were carried out. The results indicate that the thermal treatments afforded to produce high-silica RHA with cristobalite and tridymite crystalline phases that indicate the potential of RHA to be used as raw material to obtain advanced silica-based ceramic products. RHA particle size increased with treatment temperature, followed by a slight increase in specific weight and a drastic drop in surface area. Electrical characterization showed that silica particles are closely packed to a carbon film.