Binary biosorption of copper and lead onto pine cone shell in batch reactors and in fixed bed columns

• Removal of Cu and Pb from aqueous solutions by biosorption onto pine cone shell was studied.
• The competence between metal cations takes place in this binary system.
• Pine cone shell had more affinity for lead than for copper ions.
• Extended Sips model was the best to reproduce experimental results in batch systems.
• Desorption studies indicated that Cu,Pb-loaded PCS could be eluted by 0.3 M HCl.

In the present work, biosorption of copper(II) in the presence of lead(II) ions by native pine cone shell (PCS) was investigated in batch and packed bed reactors. Particularly, it provides new information regarding binary biosorption of metals in continuous flow. The behavior of competitive Cu(II) and Pb(II) biosorption in batch was successfully described by the multicomponent Sips model, obtaining maximum capacities for Cu(II) and Pb(II) of 6.52 mg/g and 17.41 mg/g, respectively. The single-metal biosorption uptake capacities of the biomass for copper and lead were slightly inhibited by the presence of lead and copper, respectively. Pine cone shell removed the target metal ions in the affinity order of Pb(II) > Cu(II) quantified in mass basis. Factors such as covalent index of the metal ions may contribute to this result. In tests carried out in a packed-bed column, the biosorption capacity for Pb(II) (17.85 mg/g) was also higher than copper one (9.38 mg/g), confirming the higher selectivity of the pine cone shell for lead over copper ions in continuous system too. Finally, desorption studies indicated that Cu,Pb-loaded PCS could be easily eluted by 0.3 M HCl.