Enhanced adsorption of arsenic onto maghemites nanoparticles As(III) as a probe of the surface structure and heterogeneity

Enhanced adsorption of arsenic onto maghemites nanoparticles : As(III) as a probe of the surface structure and heterogeneity

When normalized per unit of surface area, the quantity of arsenic adsorbed at the maghemite surface remains constant for particles between 300 and 20 nm. However, nanoparticles smaller than 20 nm exhibit enhanced adsorption capacity. The origin of this observed size-dependence for adsorption or &quo...

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Veröffentlicht in:Langmuir : the ACS journal of surfaces and colloids. - 1992. - 24(2008), 7 vom: 01. Apr., Seite 3215-22
1. Verfasser: Auffan, Mélanie (VerfasserIn)
Weitere Verfasser: Rose, Jérôme, Proux, Olivier, Borschneck, Daniel, Masion, Armand, Chaurand, Perrine, Hazemann, Jean-Louis, Chaneac, Corinne, Jolivet, Jean-Pierre, Wiesner, Mark R, Geen, Alexander Van, Bottero, Jean-Yves
Format: Online-Aufsatz
Sprache:English
Veröffentlicht: 2008
Zugriff auf das übergeordnete Werk:Langmuir : the ACS journal of surfaces and colloids
Schlagworte:Journal Article Research Support, Non-U.S. Gov't Molecular Probes Arsenic N712M78A8G Ferrosoferric Oxide XM0M87F357
Beschreibung
Zusammenfassung:When normalized per unit of surface area, the quantity of arsenic adsorbed at the maghemite surface remains constant for particles between 300 and 20 nm. However, nanoparticles smaller than 20 nm exhibit enhanced adsorption capacity. The origin of this observed size-dependence for adsorption or "nano effect" is unclear. Arsenic was chosen as a probe of the surface structure to explore adsorption mechanisms occurring at the surface of maghemite nanoparticles (6 nm). Two factors contributing to the enhanced reactivity of nanoscale maghemites were determined. The first is related to a size-dependent structural modification of the surface of particles and the decrease of the occupancy of the tetrahedral site that leaves vacant, highly reactive adsorption sites. In particular, there is a site localized in a six-membered iron octahedral ring. This site is the only one for which an oxidation of As(III) occurs. The second factor relates to the thermodynamics of a decrease of the surface free energy. The high density of As adsorbed at the saturation of the surface can be related to crystal growth
Beschreibung:Date Completed 05.05.2008
Date Revised 21.11.2013
published: Print-Electronic
Citation Status MEDLINE
ISSN:1520-5827
DOI:10.1021/la702998x