Cation-exchange capacity of algae and cyanobacteria: A parameter of their metal sorption abilities

Abstract
The potential metal sorption abilities of algae and cyanobacteria were estimated as cation-exchange capacities, using a potentiometric titration method. Unicellular cyanobacteriaAnacystis nidulans, Synechocystis aquatilis, and the green microalgaStichococcus bacillaris revealed a higher maximal capacity (205–825 μeq g−1 dry wt) than filamentous macroalgaVaucheria sp. (Xanthophyceae, 41 μeq g−1 dry wt). The cation-exchange capacity decreased when external pH decreased. Different ion-exchange properties of cell surfaces of cyanobacteria and algae were observed.