(407e) Synthesis of Lithium Aluminum Silicate From Different Sources of Silica Via Sol-Gel Method

This paper studied the effect of different sources of silica on synthesizing lithium aluminum silicate (LAS) via sol-gel method. Specifically, silica from ash of none treated rice husks (rice husk ash, RHA), silica from HCl treated rice husks (Silica-RH-HCl), and fumed silica were used to prepare LAS powders under various sintering temperatures, i.e., 400, 600, 800 and 1000 °C. The X-ray diffraction (XRD) characterization clearly showed that starting from 600 °C, LAS crystals (β-spodumene) formed when fumed silica and Silica-RH-HCl were used as the silica source. On the other hand, for RHA, substantial crystalline structures formed only at 800 °C or higher. The apparent reactivity of RHA is the lowest among the three sources, while the reactivity of the low cost biogenic Silica-RH-HCl was comparable to the commercial fumed silica. This apparent reactivity of silica can be mainly attributed to its crystallinity. In brief, the lower crystallinity of the silica, the higher reactivity. Scanning electron microscopy (SEM) characterization showed that regular crystals of LAS (β-spodumene) formed from all three sources of silica at 1000 °C.