Arsenic (V) removal from aqueous solutions using natural clay ceramic monoliths

An adsorbent material arranged in a ceramic monolith (CM) obtained by extrusion technique using natural bentonite and alumina (as raw materials) is presented. Ceramic and raw materials were characterized by X-ray fluorescence, thermal analysis, X-ray diffraction, and textural analysis (with N-2 adsorption-desorption at 77 K and Hg intrusion-extrusion porosimetry) to determine their chemical and physical properties. Then, As (V) adsorption capacity of the CM at different pH (3-9) using arsenic aqueous solution (with 2000 mu g As (V) L-1) was evaluated. Additionally, studies of kinetics and equilibrium of As (V) adsorption on CM were performed. It was found that: (i) the As (V) removal capacity is favored at acidic pH, reaching an average value of 15 mu g As (V) per gram of CM; (ii) from kinetic studies, As (V) adsorption on CM occur in two stages, the first of them reaching a lower As uptake in a short time period, followed by an slow second stage with a subsequent higher As uptake, which continued for a longer time period, reaching equilibrium conditions in approximately 24 h; and (iii) the As (V) adsorption isotherm is a type-Langmuir, indicating that the CM present an homo quantity of fixed sites to adsorb the As (V).