Adsorption capacity of the corrosion products of nanoscale zerovalent iron towards emerging contaminants
Résumé
Despite the extensive use of nanoscale zerovalent iron (NZVI) in water and soilremediation, no data exist on the reactivity of secondary iron minerals formed upon theNZVI corrosion. Herein, we investigated the oxidation kinetics of NZVI by monitoringthe variations of pH, oxidation−reduction potential (ORP) and dissolved Fe(II)concentration, and then examined the reactivity of resulting oxidized particles for theadsorption of an emerging contaminant (nalidixic acid (NA)). NA adsorption was foundgreatest onto oxidized particles and negligible on the fresh NZVI. Interestingly, theformed secondary mineral phases exhibited an unusual pH adsorption-curve with anunexpected great adsorption at alkaline pH values. X-ray photoelectron spectroscopyand high resolution-transmission electron microscopy revealed a gradual increase inFe(II) content at the surface of magnetite phase over the reaction time. Additionalexperiments and surface complexation modeling showed that the enhanced adsorptionof NA onto the secondary magnetite is due to the formation of surface bound Fe(II).Fe(II) release into solution because, for instance, of the presence of organic buffermolecules, decreased surface Fe(II) and then NA adsorption at alkaline pH values. Thiswork sheds light on an overseen aspect of the reactivity of secondary iron mineralsresulting from NZVI passivation, which can bind co-exiting emerging contaminantsand then affect their fate in the environment.
Domaines
Géochimie
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Deng et al-Adsorption capacity of the corrosion products of nanoscale-Revised ms clean-1.pdf (1.31 Mo)
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