Óxido de Ferro Peletizado como Adsorvente para a Remoção de Arsênio Dissolvido em Água

Resumo

The removal of arsenic from natural water has been successfully performed using iron oxides as adsorbent. However, this adsorbent is frequently applied in batch system due to its small particle size. Is this sense, the goal of this work is to produce industrial-scale nanostructured hematite (NH) pelletized applied to the removal of arsenic from wastewater. Pellets were prepared with the addition of bentonite (7% m/m) to produce a material suitable for use in fixed bed units. The pelletized solids, as well as a similar commercial material (GEH), were characterized by determination of friability, X-ray fluorescence (FRX), pH in the point of zero charge (pH_pzc), specific area and pore size distribution, scanning electron microscopy (SEM) and X-ray powder diffraction (XRD). The adsorption capacity was determined in finite bath and fixed bed column, evaluating the removal efficiency of arsenic in aqueous solution and effluent derived from acid mine drainage. The Langmuir and Freundlich models were used for fitting the adsorption isotherms, which presented adsorptive capacity of 9.0, 7.25 and 7.19 mg g^-1 for nanostructured hematite pellets (NHP), nanostructured hematite+7%bentonite (NHP7B)  and GEH, respectively, in pH 4.0. The results of the adsorption in fixed bed column showed an adsorption capacity of 1.25x10^-3, 0.89x10^-3 and 15.07x10^-3 mg g^-1 for NHP, NHP7B and GEH, respectively.