Comparative analysis of the biosorption of cadmium, lead, nickel, and zincby algae

Thirty strains of algae were examined for their biosorption abilities in th e uptake of cadmium, lead, nickel, and zinc from aqueous solution, A wide r ange of adsorption capacities between the different strains of algae and be tween the four metals can be observed. The cyanophyceae Lyngbya taylorii ex hibited high uptake capacities for the four metals. The algae showed maximu m capacities according to the Langmuir Adsorption Model of 1.47 mmol lead, 0.37 mmol cadmium, 0.65 mmol nickel, and 0.49 mmol zinc per gram of dry bio mass. The optimum pH for L. taylorii was between pH 3 and 7 for lead, cadmi um, and zinc and between pH 4 and 1 for nickel. Studies with the algae indi cated a preference for the uptake of lead over cadmium, nickel, and zinc in a four metal solution. The metal binding abilities of L. taylorli could be improved by phosphorylation of the biomass. The modified biosorbent demons trated maximum capacities of 2.52 mmol cadmium, 3.08 mmol lead, 2.79 mmol n ickel, and 2.60 mmol zinc per gram of dry biomass. Investigations with phos phated L. taylorii indicated high capacities for the four metals also at lo w pH. The selectivity remained quite similar to the unmodified algae.