Original Articles
Ogbonna A. C., Abii T. A. and
Abstract
The efficiencies of agricultural wastes from two different species of cassava-manihot esculenta cranz (ME) and manihot walkarae (MW) as adsorbents in removing Cd(II), Ni(II) and Pb(II) from aqueous solutions were compared. Batch adsorption experiments were carried out as a function of pH and concentration. The adsorption results were analyzed by the Langmuir, Freundlich, Dubinin-Radushkevich, Temkin, Harkins Jura and Halsey isotherm models using linearized correlation coefficient values. The characteristic isotherm parameters for each isotherm were determined and results obtained showed that Freundlich and Halsey best represented the equilibrium data for the metal ions-adsorbents systems. This was followed by the Langmuir model. The optimum pH for adsorption of Pb(II) and Ni(ll) on both adsorbents (ME and MW) occurred at 4.5 having maximum removal efficiencies of 98.94% and 93.05% respectively for Pb(II) and Ni(II) adsorption onto ME and 96.79% and 91.04% for adsorption onto MW following the initial order. Cd(II) exhibited a different pH dependence having maximum removal at pH 6.5 on both adsorbents and with removal efficiencies of 96.74% for ME and 96.23% for MW.