Ricerc@Sapienza

The removal of hexavalent Chromium from aqueous solutions by adsorption method has been investigated. In this study, magnetic nanoparticles were used as adsorbent materials and their synthesis was performed by using two different ways including a classical ammonia synthesis (nMG) and a green approach by using fructose and NaOH (GnMG). The Cr(VI) removal tests demonstrated that the synthesis procedure adopted did not influence the results. The same adsorption kinetic was observed according to a pseudo-first order with 0.026 min-1 and 0.032 min-1 as kinetic constants respectively for GnMG and nMG. In the case of high Cr(VI) concentration (20 mg L-1), the effect of nanoparticle dimension was relevant in which low nanoparticle size (44.1 nm) of nMG corresponded to a high adsorption capacity. The effect of pH on the adsorption process was investigated. Increasing the pH value to neutral condition (pH = 6) has a positive effect on the Cr(VI) removal. In contrast, the alkaline condition negatively affects the adsorption process by a reduction about 30 % of the total Cr(VI) obtained at pH= 6.