EQUILIBRIUM AND KINETIC STUDIES OF THE SORPTION OF Cd(II) AND Zn(II)BY COCOA POD HUSK

摘要

Cocoa pod husk was used for equilibrium sorption uptake studies of Cd2+ and Zn2+ from aqueous solutions in a batch system. The effects of contact time, pH and initial metal ions concentration were investigated. The experimental data were analyzed using Langmuir and Freundlich isotherm models. The results showed that the biosorption equilibrium was better described by the Freundlich than the Langmuir isotherm and that the maximum metal uptake for Cd~(2+) was higher than that of Zn~(2+). From the sorption kinetic studies, it was observed that at 30 °C, equilibrium was reached after 120 min. The sorption equilibrium was better predicted by pseudo-second-order kinetic model. The metal sorption was pH dependent and optimum values were obtained at pH 6 for the two metals.