Synthesis and Characterization of Nano-Wollastonite from Rice Husk Ash and Limestone

Wollastonite, CaSiO3 material was prepared from rice husk ash, as the source for SiO2 and limestone, source for CaO using sot-gel method. Rice husk ash and CaO powder was mixed together in 100ml distilled water with the rice husk ash/CaO ratios of 45:55 and 40:60. The mixed solution was place in the autoclave and heated at 135 degrees C for 4 hours and calcined at 950 degrees C for 1 and 2 hours. From the XRD results, ratio of 45:55 exhibited that beta-wollastonite is the major phase and the minor phase is only contributed by cristoballite and by calcining the mixture for 2 hrs would yield better crystallinity. Both of the rice husk ash:CaO ratios produced wollastonite materials in cylinder structures. Wollastonite with nano size grain was obtained for an hour calcination and 2 hrs of calcination would increase the grain size over 100 nm for ratio, 45:55 and 40:60. Therefore in order to get the nano size of wollastonite material, period of calcination process has to be controlled.