STUDIES ON THE BIOSORPTION OF HEAVY-METALS ONTO CHLORELLA-VULGARIS

The metal binding characteristics of Chlorella vulgaris were investiga ted. Metal uptake by intact algal cells was found to consist of two pr ocesses; (1) a fast, metatbolism-independent surface reaction and (2) metabolism-dependent slow uptake. Results of both the pH and the ionic strength effects on the metal adsorption indicate that the specific i nteraction accounts for the majority of metal adsorption. Carboxyl and amine surface functional groups of Chlorella vulgaris were modified t o assess the role of the surface charge site as the metal binding one. The carboxyl-modified algae showed major decreases in the adsorption capacity of Cd(II) and Zn(II) binding. The amine-modified algae also d isplayed some decreases in metal adsorptions.