Rice husk as raw material in the synthesis of analcime

Rice husk is an agricultural waste from rice milling and nowadays represents an important substitute of 
silica in synthesis protocols of industrial minerals. Synthesis of monomineralic powders of Analcime by 
rice husk is here achieved with the conventional hydrothermal method; an improvement in synthesis 
conditions compared to the past is achieved by lowering rice-husk calcination temperatures, synthesis 
temperatures, crystallization times and by avoiding aging times. Rice husk is subjected to calcination 
at the temperature of 550 °C and then mixed with NaOH and NaAlO2. The experiment is performed at 
environment pressure and 170 ± 0.1 °C for 77 h. Analcime is characterized by X-ray diffraction, scanning 
electron microscopy, infrared and Raman spectroscopy. Cell parameters and the amount of amorphous 
phase in the synthesis powders is described with quantitative phase analysis using the combined 
Rietveld and reference intensity ratio methods. The degree of purity of Analcime is calculated in 
97,53% at 12 h. The results show that rice husk waste represents a good alternative silicon source, and 
it can be used to produce pure analcime crystals.