INFLUENCE OF CHELATING AGENTS ON 60Co UPTAKE BY FRESH WATER ALGAE

Chlorella sp. isolated from the leaf surface of water plants was used to obtain the characteristics of cobalt biosorption using (CoCl2)-Co-60 in the presence of complexing ligands. Concentration equilibrium of Co biosorption was reached Within One hour at 22 degrees C, and the process was not pH dependent within the range pH 4 to 7. Cobalt biosorption capacity Q(max) = 14.5 mg.g(-1) (d.w.) was reached from the Co2+ solution >= 1 mmol.dm(-3). Biosorption is diminished in the presence of complexing ligands. The efficiency of ligands to suppress Co biosorption increased in the order: citrate < NTA < EDTA. Because Chlorella genus is a common autochthonous green algae population of shallow fresh waters, it can play a decisive role in decontamination of waters polluted with cobalt in inorganic Co2+ form originating from chemical or nuclear wastes.