A comparative investigation on the biosorption of lead by filamentous fungal biomass

The removal of lead from aqueous solutions by adsorption on filamentous fun gal biomass was studied. Batch biosorption experiments were performed to sc reen a series of selected fungal strains for effective read removal at diff erent metal and biomass concentrations. Biosorption of the Pb2+ ions was st rongly affected by pH. The fungal biomass exhibited the highest lead adsorp tion capacity at pH 6. Isotherms for the: biosorption of lead on fungal bio mass were developed and the equilibrium data fitted well to the Langmuir is otherm model. At pH 6, the maximum lead biosorption capacity of Mucor rouxi i estimated with the Langmuir model was 769 mg/g dry biomass, significantly higher than that of most microorganisms. Biomass of Mucor rouxii showed sp ecific selectivity for Pb2+ over other metals ions such as Zn2+, Ni2+ and C u2+. This fungal strain may be applied to develop potentially cost-effectiv e biosorbent Ibr removing lead from effluents. The technique of scanning el ectron microscopy coupled with X-ray dispersion analysis shows that Pb2+ ha s exchanged with K+ and Ca2+ on the cell wall of Mucor rouxii, thereby sugg esting ion exchange as one of the dominant mechanisms of metal biosorption for this fungal strain. (C)1999 Elsevier Science Ltd. All rights reserved.