Np(V) Retention at the Illite du Puy Surface.

In this study, Np(V) retention on Illite du Puy (IdP) was investigated since it is essential for understanding the migration behavior of Np in argillaceous environments. The presence of structural Fe(III) and Fe(II) in IdP was confirmed by Fe K-edge X-ray absorption near-edge structure (XANES) and Fe Mössbauer spectroscopy. In batch sorption experiments, a higher Np sorption affinity to IdP was found than to Wyoming smectite or iron-free synthetic montmorillonite.

Paving the way for examination of coupled redox/solid-liquid interface reactions: 1 ppm Np adsorbed on clay studied by Np M-edge HR-XANES spectroscopy.

The recently emerged actinide (An) M-edge high-energy resolution X-ray absorption near-edge structure (HR-XANES) technique has proven to be very powerful for oxidation state studies of actinides. In this work, for the first time, Np M-edge HR-XANES was applied to study Np sorption on illite. By improving the experimental conditions, notably by operation of the spectrometer under He atmosphere, it was possible to measure Np M-edge HR-XANES spectra of a sample with ≈ 1 μg Np/g illite (1 ppm).