The influence of chemical and thermal treatments on the fluoride removal from water by three mineral structures and their characterization

Abstract

In the present work three different natural materials and their modifications were studied for fluoride removal from aqueous solutions. The materials employed were: clinoptilolite (C), montmorillonite (M) and pumice (P), the minerals were modified with Fe3+ and Al3+ and heated at temperatures of 200, 500 and 800 °C. They were characterized by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), specific surface area by Branauer Emmett and Teller method (BET) and points of zero charge (pzc). Adsorption experiments were carried out in batch system to obtain the adsorption capacity of each material and evaluate the leaching of iron and aluminum after adsorption processes, throughout the quantification of Fe3+ and Al3+ in the supernatants. The results obtained indicated the following adsorption capacity order: M (1.008 mg/g)>aluminum-modified materials > iron-modified materials > C > P.