EFFECT OF CHEMICAL MODIFICATION OF ALGAL CARBOXYL GROUPS ON METAL-ION BINDING

Carboxyl groups of biomasses of five different algal species were esterified by using acidic methanol. The extent of esterification was monitored by analyzing the amount of methanol released in the sample hydrolysates by gas chromatography. The effect and extent of esterification on copper(II) binding to the biomass was determined at pH 5.0 and 2.0. All methanol-modified biomasses showed major decreases in copper(II) and aluminum(III) binding, although the amount of decrease varied among algal species. In contrast, gold(III) binding capacities slightly increased as the algal carboxyl groups were esterified. These results indicate that carboxyl groups on algal cells are responsible for a great portion of copper(II) and aluminum(III) binding, and that they play an inhibitory role in gold(III) binding. © 1990, American Chemical Society. All rights reserved.