Synthesis and characterization of NaX and Cu-exchanged NaX zeolites from silica obtained from rice husk ash

Sodium X zeolite and a number of other zeolites such as P-C, HS and analcime were synthesized using rice-husk ash as a source of silica. Also, a number of NaCuX zeolites were prepared by ion-exchange method with copper contents from 2.8 to 10.5 wt%. The products were characterized using X-ray diffraction analysis. The morphological characteristics of the prepared zeolites were also studied. The NaX zeolite exhibits typical octahedral form whereas analcime and zeolite Pc have trapezohedral and spheroid forms, respectively. Differential thermal patterns of NaCuX zeolites revealed the presence of an initial sharp and intense endotherm for dehydration around 190-220 degrees C followed by an exotherm around 830-860 degrees C. representing structural change and dissociation, which were confirmed by X-ray diffraction analysis.