Removal of Zn(II) ions from aqueous media on thermal activated sawdust

The adsorptive characteristics of thermal activated sawdust were examined for the removal of Zn(II) ions from aqueous solution. Batch experiments were performed in order to study the influence of initial Zn(II) concentration and contact time under optimal experimental conditions (initial solution pH of 1.09 and 6.23, 8.0 g/l) and the results were compared with those obtained on non-activated sawdust. A significant increase in adsorption capacity of thermal activated sawdust for Zn(II) ions, with 77.19% at pH 1.09 and with 395.12% at pH 6.23, was obtained at highest Zn(II) initial concentration of 78.50 mg/L. The equilibrium data of Zn(II) adsorption onto non-activated sawdust are very well described by the Langmuir model, while in case of Zn(II) adsorption onto thermal activated sawdust, the Freundlich model is more suitable for the fitting of experimental data. From kinetic point of view, the Zn(II) adsorption on thermal activated and non-activated sawdust attains the maximum after 60 min of contact time and follows the pseudo-second-order mechanism. The thermal activated sawdust has incontestable improved adsorptive characteristics for Zn(II) removal from aqueous solutions.