Adsorption characteristics studies on removal of Cr (VI) from aqueous solution by using Casuarina equisetifolla

Abstract

In this research, adsorption of chromium (VI) ions on Casuarina equisetifolla has been studied through using batch adsorption techniques. The main objectives of this study are to 1) investigate the chromium adsorption from aqueous solution by Casuarina equisetifolla, 2) study the influence of contact time, pH, adsorbent dose and initial chromium concentration on adsorption process performance and 3) determine appropriate adsorption isotherm and kinetics parameters of chromium (VI) adsorption on Casuarina equisetifolla. The results of this study showed that adsorption of chromium by Casuarina equisetifolla reached to equilibrium after 60 min and after that a little change of chromium removal efficiency was observed. Higher chromium adsorption was observed at lower pHs, and maximum chromium removal (96.1 %) obtained at pH of 2. The adsorption of chromium by Casuarina equisetifolla decreased at the higher initial chromium concentration and lower adsorbent doses. The obtained results showed that the adsorption of chromium (VI) by Casuarina equisetifolla follows Langmuir isotherm equation with a correlation coefficient equal to 0.984. In addition, the kinetics of the adsorption process follows the pseudo second-order kinetics model with a rate constant value of 0.0185 g/mg.min The results indicate that Casuarina equisetifolla can be employed as a low cost alternative to commercial adsorbents in the removal of chromium (VI) from water and wastewater.