Adsorptive properties of Moroccan clays for the removal of arsenic(V) from aqueous solution

The aim of this work was to study arsenic adsorption behavior onto clayey materials from Morocco. Five samples were investigated: R-clay and Y-clay from Oued Laou (Tetouan region), E-clay and A-clay from Tetouan City and Rhassoul-clay from the East side of the Middle Atlas Mountains, in the Moulouya Valley, approximately 200 km away from Fes. A thorough characterization of these five samples was performed. Adsorption studies were conducted in batch system as a function of time, pH and initial As concentration. The effect of the pH on the adsorption of As for the 5 clays indicated that the arsenic adsorption was most favorable in the acidic pH range for R-clay, A-clay and E-clay. For Rhassoul-clay and yellow clay, no significant adsorption was found in the whole pH range considered. Langmuir and Freundlich isotherms were used for the interpretation of sorption isotherms data. Langmuir model provided the best fit with the experimental adsorption isotherm data obtained with R-clay. The adsorption onto E-clay and A-clay could be described both by the Langmuir and Freundlich models. For Y-clay and Rhassoul-clay, the sorption efficiency was too low and it was therefore not possible to determine the favorable models. R-clay is the most effective adsorbent with a maximum adsorption capacity of 1.076 mg.g(-1) Therefore, the R-clay is an efficient and economical adsorbent and could be used for the removal of arsenic from water. (C) 2015 Elsevier B.V. All rights reserved.