Antimony oxyanions uptake by green marine macroalgae

Abstract

The potential of green seaweeds, Cladophora sericea and Ulva rigida, to adsorb antimony(III) and antimony (V) from aqueous solution was studied in batch mode. The hydroxyl and carboxyl groups from the algae surface, responsible for Sb uptake, were quantified by potentiometric titration and a continuous model for the deprotonation of these sites was obtained. Kinetic studies using C. sericea as biosorbent were conducted using different initial Sb concentrations and solid/liquid ratios. A fast uptake process was observed with equilibrium being achieved in less than 2 h. Equilibrium studies show considerable adsorbed amounts for both Sb(III) and Sb(V). Maximum biosorption capacities, predicted by Langmuir model, were 2.1 mg/g, for Sb(III), and 3.1 mg/g for Sb(V), at pH 2 and 22 degrees C. A low influence of pH (range 2-8) and of ions typically present in natural waters were shown to be additional advantages of C. sericea, as a potential biosorbent for antimony.