Natural seaweed waste as sorbent for heavy metal removal from solution

Abstract

Biosorption is a suitable heavy metal remediation technique for the treatment of aqueous effluents of large volume and low pollutant concentration. However, today industrial applications need the selection of efficient low‐cost biosorbents. The aim of this work is to investigate brown alga such as Fucus serratus (FS) as a low‐cost biosorbent, for the fixation of metallic ions, namely Cu²⁺, Zn²⁺, Pb²⁺, Ni²⁺, Cd²⁺ and Ce³⁺, in a batch reactor. Biosorption kinetics and isotherms have been performed at pH 5.5. For all of the studied metallic ions, the equilibrium time is about 450 min and a tendency based on the initial sorption rate has been established: Ce³⁺ > Zn²⁺ > Ni²⁺ > Cu²⁺ > Cd²⁺ > Pb²⁺. The adsorption equilibrium data are well described by the Langmuir equation. The sequence of the maximum adsorption capacity is Pb²⁺ ≈ Cu²⁺ ≫ Ce³⁺ ≈ Ni²⁺ > Cd²⁺ > Zn²⁺ and values are ranged between 1.78 and 0.71 mmol g⁻¹. These results indicate that the FS biomass is a suitable biosorbent for the removal of heavy metals from wastewater and can be tested in a dynamic process. The selected pilot process involves a hybrid membrane process: a continuous stirred tank reactor is coupled with a microfiltration immersed membrane, in order to confine the FS particles. A mass balance model is used to describe the adsorption process and the breakthrough curves are correctly modelled. Based on these results, it is demonstrated that FS is an interesting biomaterial for the treatment of water contaminated heavy metals.

Keywords:

• low‐cost biosorbent
• brown alga
• heavy metal
• biosorption capacities
• dynamic studies

Acknowledgements

The authors thank the Iranian Research Ministry, the French Embassy in Tehran, and Egide for the financial grant awarded to Salman AHMADY ASBCHIN, PhD student in 2004–2008.