Aqueous U(VI) interaction with magnetite nanoparticles in a mixed flow reactor system: HR-XANES study

16th International Conference on X-ray Absorption Fine Structure

Pidchenko, I.^1 ; Heberling, F.^1 ; Kvashnina, K.O.^2 ; Finck, N.^1 ; Schild, D.^1 ; Bohnert, E.^1 ; Schäfer, T.^1 ; Rothe, J.^1 ; Geckeis, H.^1 ; Vitova, T.^1

Institute for Nuclear Waste Disposal (INE), Karlsruhe Institute of Technology, PO 3640, Karlsruhe

76021, Germany^1

European Synchrotron Radiation Facility (ESRF), 6 Rue Jules Horowitz, Grenoble Cedex

38043, France^2

关键词: Atomic environment;    Continuous injections;    Dynamic flow conditions;    High-energy resolution;    Mixed-flow reactors;    Operation time;    Proof-of-principle experiments;    X ray absorption near edge structure;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/712/1/012086/pdf
DOI  :  10.1088/1742-6596/712/1/012086

来源: IOP

【 摘 要 】

The redox variations and changes in local atomic environment of uranium (U) interacted with the magnetite nanoparticles were studied in a proof of principle experiment by the U L3and M4edges high energy resolution X-ray absorption near edge structure (HR-XANES) technique. We designed and applied a mixed flow reactor (MFR) set-up to maintain dynamic flow conditions during U-magnetite interactions. Formation of hydrolyzed, bi- and poly-nuclear U species were excluded by slow continuous injection of U(VI) (10-6M) and pH control integrated in the MFR set-up. The applied U HR-XANES technique is more sensitive to minor changes in the U redox states and bonding compared to the conventional XANES method. Major U(VI) contribution in uranyl type of bonding is found in the magnetite nanoparticles after three days operation time of the MFR. Indications for shortening of the U-Oaxialbond length for the magnetite compared to the maghemite system are present too.