Effect of Calcination Temperature and Time on the Physicochemical Properties of Rice Husk Ash and Eggshell Ash for Zeolite Synthesis

The conversion of agricultural and biogenic wastes into functional materials offers a sustainable pathway for resource recovery. Rice husk ash and eggshell ash, which are rich in silica and calcium, respectively, are promising raw materials for zeolite synthesis. However, their effectiveness depends strongly on calcination conditions. This study investigated the influence of calcination temperature and calcination time on the physicochemical properties of rice husk ash and eggshell ash. Calcination was carried out at temperatures between five hundred and eight hundred and fifty degrees Celsius for durations ranging from two to six hours. The calcined materials were characterized using x ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, and surface area analysis. Results showed that rice husk ash calcined at seven hundred degrees Celsius produced highly reactive amorphous silica with minimal carbon residues, while higher temperatures promoted partial crystallization. Eggshell ash exhibited progressive calcium carbonate decomposition with increasing temperature, leading to calcium oxide rich phases at higher temperatures, although prolonged heating resulted in particle coarsening. The study demonstrates that controlled calcination is essential for tailoring the reactivity and structural integrity of rice husk ash and eggshell ash, thereby supporting their application as low cost and sustainable precursors for zeolite synthesis.