Removal of Lead and Cadmium Ions from Aqueous Solution using Walnut Shells as Low-Cost Adsorbent Materials

In this study dry walnut shells were used as adsorbent to remove of Pb(II) and Cd(II) ions from aqueous solution through batch adsorption of single component. An investigation was carried out to identify the effect of pH, initial concentration of the heavy metal's ions, contact time, dose and size diameter of adsorbent on the removal efficiency at 25 C degrees. Isotherm adsorption parameters were determined by using both Langmuir and Freundlich models. Two simplified kinetic models including a pseudo-first-order equation and pseudo-second-order equation were selected to follow the adsorption process. Results showed that the maximum removal efficiency of Pb(II) and Cd(II) ions are 86.16% and 72.35% respectively in the best conditions. The experimental data fitted better to the Langmuir isotherm model than to Freundlich isotherm model. The experimental data proved that the adsorption kinetic of Pb(II) and Cd(II) ions could be described by a pseudo-second order model.