Zeolitization of a bentonite and its application to the removal of ammonium ion from waste water

Abstract In this study a bentonite was modified to zeolitic material by alkaline treatment in distilled and seawater media. The alkaline treatment was performed using two different methods: a reflux system and in an autoclave. The structural and textural characteristics of the natural clay were measured and compared to those of the modified clays formed. The samples were characterized by X-ray diffraction (XRD), infrared spectroscopy (IR), thermogravimetric analysis (TG), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDRXA) and cation exchange capacity (CEC). The laminar structure of the starting material was converted into spherical units in the zeolitic nature. The modifications observed were greater in the samples treated in the autoclave than by reflux, and also greater when the treatment medium was distilled water rather than seawater. The capacity of the treated samples to remove ammonium ions from distilled water and seawater was compared with the original samples. It was found that CEC and ammonium removal were increased by alkaline treatment. Ammonium removal was more efficient from distilled water, where there were no competitive ions. The materials generated by alkaline treatment in seawater were more selective for ammonium removal. The samples obtained in seawater were not influenced by the treatment conditions (reflux/autoclave).