Enhanced Adsorption of Arsenic onto Maghemites Nanoparticles: As(III) as a Probe of the Surface Structure and Heterogeneity

• DOI: 10.1021/la702998x
• Publication Date: 2008-02-12T10:01:24Z
• Authors: Mélanie Auffan; Jérôme Rose; Olivier Proux; Daniel Borschneck; Armand Masion; Perrine Chaurand; Jean-Louis Hazemann; Corinne Chaneac; Jean-Pierre Jolivet; Mark R. Wiesner; Alexander Van Geen; Jean-Yves Bottero
• Keywords: Maghemite; Saturation (graph theory)

When normalized per unit of surface area, the quantity arsenic adsorbed at maghemite remains constant for particles between 300 and 20 nm. However, nanoparticles smaller than nm exhibit enhanced adsorption capacity. The origin this observed size-dependence or "nano effect" is unclear. Arsenic was chosen as a probe structure to explore mechanisms occurring (6 nm). Two factors contributing reactivity nanoscale maghemites were determined. first related size-dependent structural modification decrease occupancy tetrahedral site that leaves vacant, highly reactive sites. In particular, there localized in six-membered iron octahedral ring. This only one which an oxidation AsIII occurs. second factor relates thermodynamics free energy. high density As saturation can be crystal growth.