Removal of Chromium (III) from Aqueous Solution by Coconut Husk and Rice Straw

Abstract

Coconut husk fibre and rice straw were found to be able to remove significant amount of Cr (III) ions from aqueous solutions. Its removal is a function of pH and concentration. The optimum pH range for maximum uptake is between 4 and 6 for both substrates. The adsorption capacity was found to be 0.55 and 0.30 millimole Cr (III) / g substrate for coconut husk and rice straw respectively. The adsorption kinetic studies show that the removal process follows a first order rate expression. The breakthrough curves and adsorption efficiency of various columns containing mixed media of coconut husk/rice straw, soil and sand have been obtained. The results demonstrate that these agricultural residues could be used as barriers in a landfill to maximize immobilization of toxic metal ions such as Cr (III) in leachates.