Biosorption of antimony and chromium species by Spirulina platensis and Phaseolus. Applications to bioextract antimony and chromium from natural and industrial waters
The ability of the two biological substrates, Spirulina platensis (a cyanobacterium) and Phaseolus (a plant-derived material) to accumulate Sb and Cr species (SbIII, SbV, CrIII and CrVI) was evaluated. Different parameters affecting accumulation were tested: pH, temperature, incubation time, amount of biomass and analyte, presence of foreign ions and the influence of the oxidation state. The experimental data were modeled using sorption isotherms and the corresponding sorption coefficients of each species were calculated for both substrates. S. platensis and Phaseolus were suitable for the accumulation of Sb and Cr species over a wide variety of experimental conditions and the accumulation depended on the oxidation state of the analyte. S. platensis was applied to preconcentrate Sb and Cr in river and sea-water samples. The detection limits of the electrothermal atomic absorption spectrometric procedures obtained for Sb in river water (preconcentration factor 4) and sea-water samples (preconcentration factor 40) were 0.9 and 0.09 µg l–1 , respectively, and those for Cr were 0.1 µg l–1 (preconcentration factor 10) and 0.05 µg l–1 (preconcentration factor 20), respectively. The removal of chromium ions from a leather industrial waste water was also examined using this substrate. S. platensis was able to remove 97% of Cr from the waste water and therefore proved to be an alternative for the reclamation and remediation of contaminated waters. The vegetable substrate Phaseolus, is highly promising for speciation purposes at low analyte concentrations.