Sorption of Gold by Naked and Thiol-Capped Magnetite Nanoparticles: An XPS Approach

Iron oxide nanoparticles are promising materials for many technological and environmental applications due to their versatile functionalization and magnetic properties that allow a facile remote control, separation and analyte recovery. In this contribution, the results of gold(III) sorption by naked and DMSA-capped (DMSA = m-2,3,dimercapto succinic acid) magnetite nanoparticles are discussed. Magnetite nanoparticles of 8 nm diameter were first synthesized by thermal decomposition of iron(III) oleate followed by a ligand exchange reaction to substitute oleic acid (OA) molecules by DMSA. Such systems of coated magnetite nanoparticles were characterized with Fourier transform infrared (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM) and magnetic measurements. FT-IR spectroscopy suggests that in Fe3O4@DMSA the organic coating is not homogeneous and it interacts with surface iron cations either through the carboxylate groups (by forming bridging bidentate complexes) or through disulfid...