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

Abstract

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 P_C 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^oC followed by an exotherm around 830-860^oC representing structural change and dissociation, which were confirmed by X-ray diffraction analysis.