Magnetic and density separation methods have been applied to composite sediment samples from the Hanford formation from sediment recovered during drilling of an uncontaminated borehole located near the 200 West Area of the Hanford Site in southeastern Washington State. This paper describes the results of using those separation methods and from the characterization and initial reactivity measurements on a highly magnetic fraction isolated from that sediment. X-ray diffraction (XRD) analysis of the highly magnetic sediment fraction indicates that this material contains predominantly magnetite (Fe3O4). Particle morphology observed by scanning electron microscopy (SEM) and compositions determined energy dispersive spectroscopy (EDS) are consistent with this identification. Analyses by X-ray photoelectron spectroscopy (XPS) indicates that there is a thin coating on the particles that are likely a type of aluminosilicate. This highly magnetic fraction of material is not reactive with indigo carmine, an organic redox probe molecule that was shown to readily react with synthetic magnetite. Because of the limited amounts of material readily available, initial tests have been conducted that demonstrate the ability to complete U(VI) sorption on individual particles (nominally ∼100μm in size) of the isolated sediment and to remove and mount these individual particles for analysis of the concentration and chemical state of the sorbed U species using small area XPS.
Bibliographical noteFunding Information:
M.H. Engelhard, H.T. Schaef, and N.T. Saenz and J.E. Coleman (all at PNNL) are acknowledged, respectively, for collection and analysis of XPS, μXRD, and SEM/EDS data. This research was supported by the Environmental Remediation Science Program (ERSP), Office of Biological and Environmental Research (BER), US Department of Energy (DOE). A portion of the research was performed using EMSL, a national scientific user facility sponsored by DOE-BER and located at Pacific Northwest National Laboratory (PNNL). PNNL is operated for DOE by Battelle under contract DE-AC06-76RLO 1830.
- Hanford sediment
- Natural magnetite