Removal of Cu(II) and Pb(II) ions from aqueous solutions by adsorption on sawdust of Meranti wood

Meranti tree sawdust, an inexpensive material, is currently being investigated as an adsorbent for the removal of Cu(II) and Pb(II) ions from aqueous solutions. In this work, adsorption of Cu(II) and Pb(II) ions on Meranti tree sawdust has been studied by using batch techniques. The equilibrium adsorption level was determined to be a function of the solution of pH, contact time, and adsorbent dosage. Adsorption isotherms of Cu(II) and Pb(II) ions on adsorbents were determined and correlated with common isotherm equations such as Langmuir and Freundlich models. The thermodynamic parameters like free energy, enthalpy, and entropy changes for the adsorption of Cu(II) and Pb(II) ions have also been computed and discussed. The heat of adsorption [DH = 31.47 kJ/mol for Cu(II) and DH = 20.07 kJ/mol for Pb(II)] implied that the adsorption was endothermic in nature.

Based on the present study, it is clearly shown that sawdust obtained from Meranti wood is an effective adsorbent for the removal of Cu(II) and Pb(II) ions from aqueous solution. The adsorption process is strongly affected by parameters such as time, pH, adsorbent dosage, and temperature. The equilibrium time for Cu(II) and Pb(II) ions is determined as 60 min. The percentage adsorption for Pb(II) seems to be greater than adsorption of Cu(II) in this equilibrium time. The plot of pH versus percentage adsorption shows significant adsorption at pH 6.60 for the Cu(II) ions and at pH 7.00 for the Pb(II) ions. The removal is almost 100% for Cu(II) at this pH value being 99.39%. On the other hand, percentage removal for Pb(II) at this pH is 94.61%. The percentage adsorption of Cu(II) and Pb(II) ions was increased with increasing the adsorbent dosage. The adsorption of Cu(II) and Pb(II) ions on sawdust at pH 6.60 and 7.00, respectively, follow both Freundlichand Langmuir-type adsorption isotherms. Thermodynamic constants were also evaluated using equilibrium constants changing with temperature. The negative value of DG for Cu(II) and Pb(II) ions indicated the spontaneity of the process. The positive value of DH showed the endothermic nature of Cu(II) and Pb(II) sorption, respectively. Acknowledgment The study was funded through USM shortterm grant number 304/ PTEKIND/ 637044. The authors acknowledge the USM for providing research facilities.