Removal of Chromium (Cr3+) and (Cr6+) from Aqueous Solutions Using Leonardite

The presence of chromium in drinking water and the entry of industrial wastewater into groundwater resources endangers human health and the environment. This study was done to investigate the effect of leonardite to remove Cr+6, Cr+3 from aqueous environments. The optimal values of factors were determined by the surface response model and the central composite design. Adsorption data were fitted with the pseudo-first order and pseudo-second order kinetic models. In addition, the effects of interfering cations and anions on chromium adsorption were determined. The results showed that the contact time, amount of leonardite and pH significantly affect chromium sorption. Chromium kinetic data were well fitted (R2=0.995) to the pseudo second order equation. The capacity (qe) and adsorption coefficient (Kads) parameters for Cr3+ were higher than Cr6+. As a large amount of Cr3+ was adsorbed by leonardite in a short time. Fe3+ and SO42- as interfering ions reduced the removal of Cr3+ and Cr6+ by leonardite respectively. It is concluded that Leonardite, as a biodegradable adsorbent, is suitable for remove of chromium from contaminated waters.