Characterization of exopolysaccharides after sorption of silver ions in aqueous solution
Résumé
Biosorption of silver ions by several exopolysaccharides (EPS) differing from each other in their chemical
composition and functional groups was investigated. EPS were characterized before and after Ag(I)
biosorption by comprehensively using X-ray photoelectron spectroscopy (XPS), Fourier transform
infrared spectroscopy (FTIR), X-ray diffraction, transmission electron microscopy (TEM). The role of the
different functional groups in the biosorption process was observed. In particular, sulfate groups were
seen playing a major role. XPS and FTIR methods showed that the composition of lowest efficient EPS
changed after Ag(I) biosorption with a relative increase of the carboxylate ions content. This change was
accompanied by the formation of mainly silver oxide nanoparticles. As the consequence, the reducing
character of the EPS is expected to influence the silver sorption capability of the EPS.