Efficiency of Rice Husk for Removal of Cu(II) and Zn(II) Ions from Aqueous Solution

In the present study the adsorption of Cu(II) and Zn(II) ions on rice husk from artificially prepared aqueous solutions of these metal ions was investigated following the batch mode adsorption procedure. Accordingly, the effects of operating parameters such as pH, contact time, and initial concentration of metal ion solution were evaluated. The results so obtained in this study indicated that the optimum conditions for the Cu(II) and Zn(II) ions adsorption were found to be as follows: pH of 6 and 7; contact times of 100 and 125 minutes; and these values were actually determined by setting the initial concentration of 50mg/L for each metal ion solution. Upon measurements of the residual metal ion concentration using FAAS method, the percent adsorption of both Cu(II) and Zn(II) ions showed significant increase with an increase in each case of the contact time. Furthermore, it was evidently implicated that the binding process of the metal ions on the adsorbent (rice husk) could be affected by change in the pH of both metal ion solutions. In addition the experimental data were analyzed against both Langmuir and Freundlich isotherm for determining the maximum adsorption capacity of the title biosorbent with respect to each of the tested metal ions. The adsorption maxima were calculated on the basis the Langmuir isotherm and found to be 1.93 and 12.98 mg/g for Cu(II) and Zn(II) metal ions respectively. These values were suggested that the rice husk investigated in this study can have a good application potential for the removal of both metal ions (Cu(II) and Zn(II)) from aqueous solutions. In fact, the goal of this work was to develop an inexpensive, highly available, effective metal ion adsorbent from natural waste as alternative to existing commercial adsorbents.