Chemical and structural characterization of metal-organic materials obtained through heavy metal biosorption by exopolysaccharide-producing

We aim to clarify the binding mechanisms of heavy metals (HM) to cyanobacteria exopolysaccharides (EPS) in the biosorption process, which is an innovative, eco-friendly method for HM bioremoval. To our knowledge, the speciation of HM on different EPS fractions has not been investigated yet. For this purpose, the binding between anionic groups of i) released polysaccharides (RPS) and ii) EPS that are associated with the cells surface of cyanobacteria (biosorbents) to Ni, Cu, Zn, and Au will be studied via both XANES and EXAFS techniques. Thanks to its elemental specificity and low detection limit, XAS spectroscopy represents the most suitable method to obtain information on the local atomic structure of the metals biosorbed to heterogeneous biological samples. The obtained data will provide a characterization of the metal-organic materials obtained through this process.