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.