Removal of lead from aqueous solution by non-living rhizopus nigricans

Non-living Rhizopus nigricans obtained as a waste byproduct from the pharmaceutical fermentation industry has been used for adsorption of lead over a range of metal ion concentrations, adsorption time, pH and co-ions. The process of uptake obeys both the Langmuir and Freundlich isotherms. The mechanism of lead sequestering by this type of biomass was also studied by using experimental techniques such as electron microscopy, X-ray energy dispersion analysis and IR spectroscopy. Comparison of uptake between NaOH-treated and untreated biomass shows that the adsorption takes place in the chitin structure of the cell wall.