Metal removal from single and multimetallic systems by different biosorbent materials as evaluated by differential pulse anodic stripping voltammetry

Abstract

This paper provides information on the use of differential pulse anodic stripping voltammetry (DPASV) for the measurement of the metal biosorption potential of Lemna, Microcystis field-grown (MF), Microcystis lab-grown (ML) and Spirogyra from aqueous solution containing Pb, Cu, Cd and Zn in single, bi-, tri- and multimetallic mixture. This technique was useful for the evaluation of different metal species (Pb 2+, Cu 2+, Cd 2+, Zn 2+) that exist in the test solution. Free-floating Lemna exhibited the highest (94%) Pb 2+ biosorption. This, in turn, was followed by MF (89.5%), ML (78.8%) and Spirogyra (58.4%) in single metal condition. The dead biomass of test organisms exhibited the following order of metal biosorption: Pb 2+>Cu 2+>Zn 2+>Cd 2+. In sharp contrast to single metal system, the biosorption of Cd was greater than Zn in tri- and multimetallic combination. Results indicated the following metal sorption capabilities in both single and multimetallic systems: Lemna>MF>ML> Spirogyra. All bimetallic combinations showed antagonistic interaction. Pb 2+ biosorption by Lemna, MF and ML from multimetallic combination did not depict any deviation from the single metal ion system. However, synergistic interaction (6–7% higher) for Cu 2++Cd 2++Pb 2+ and Zn 2++Cd 2++Pb 2+ combination was observed for Spirogyra. Contrary to the above, the Cu 2++Zn 2++Pb 2+ combination showed antagonistic behaviour with Spirogyra. The biosorption of Pb 2+ was never affected by the presence of other metals tested. The IR data also supported a preferential biosorption of Pb 2+ and revealed that COOH plays a major role in metal binding onto biomass surface.