Impedimetric characterization of alginate entrapped arthrospira platensis at a platinum/electrolyte interface. Effect of cadmium ions
Abstract
In this work, electrochemical impedance spectroscopy was investigated to characterize cadmium biosorption by Arthrospira platensis cyanobacterium. Biomass was immobilized at the surface of a platinum electrode in a calcium alginate matrix stabilized in 0.5 M acetate buffer pH 7. Both alginate/platinum and alginate/Arthrospira/platinum electrodes could be modelled using an association of two RC circuits representing the bulk properties of the membrane and the membrane/electrolyte interface. Ca2+ ions leakage during stabilization resulted in a significant increase of alginate film resistance and a decrease of its capacitive behaviour. Electrical parameters of the membrane varied also in presence of cyanobacteria, demonstrating the effect of biomass on alginate gel structuration and properties. Finally, affinity of cadmium ions for alginate matrix and Arthrospira platensis was characterized through the variation of membrane/electrolyte interface parameters. It was shown that only cyanobacteria interact with metal ions in the experimental conditions used.