Removal of toxic metals from aqueous solutions by biosorption

Several non-living algal and fungal biomass types were investigated for biosorption of cadmium, lead and a number of other heavy metal ions in aqueous solution. Marine algae A. nodosum was identified for the highest uptake for these metals, and even better than commercial ion exchange resin. A. nodosum maximum uptake capacities for lead and cadmium were in excess of 2590 mg Pb/(g dried biomass) and 120 mg Cd/(g dried biomass), respectively (pH:3.5-5.5). The adsorption mechanism for this natural material is reversible. Meal ions can be easily eluted from the biosorbent with dilute mineral acids. The biosorption process was investigated for equilibrium batch as well as dynamic packed bed column modes. Two different sorbent immobilization techniques, cross-linking and entrapment were developed for the packed bed studies. It was observed that A. nodosum cross-lined with formaldehyde give the best results for practical use