Journal Article

FZJ-2014-03264

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Uptake of Ra during the recrystallization of barite: a microscopic and ToF-SIMS study

Klinkenberg, M. (Corresponding Author)FZJ* ; Brandt, F.FZJ* ; Breuer, U.FZJ* ; Bosbach, D.FZJ*

2014
American Chemical Society Columbus, Ohio

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Please use a persistent id in citations: http://hdl.handle.net/2128/15977  doi:10.1021/es405502e

Abstract: A combined macroscopic and micro analytical approach was applied on two distinct barite samples from Ra uptake batch experiments using ToF-SIMS and detailed SEM investigations. The experiments were set up at near to equilibrium conditions in order to distinguish between two possible scenarios for the uptake of Ra by already existent barite, (1) formation of a Ba1-xRaxSO4 solid solution surface layer on the barite or (2) a complete recrystallization, leading to homogenous Ba1-xRaxSO4 crystals. It could be clearly shown that Ra uptake in all barite particles analyzed within this study is not limited to the surface but extends to the entire solid. For most grains a homogenous distribution of Ra could be determined, indicating a complete recrystallization of barite into a Ba1-xRaxSO4 solid solution. The maxima of the Ra/Ba intensity ratio distribution histograms calculated from ToF-SIMS are identical with the expected Ra/Ba ratios calculated from mass balance assuming a complete recrystallization.In addition, the role of Ra during the recrystallization of barite was examined via detailed SEM investigations. Depending on the type of barite used, an additional coarsening effect or a strong formation of oriented aggregates was observed compared to blank samples without Ra. In conclusion, the addition of Ra to a barite at close to equilibrium conditions has a major impact on the system leading to a fast re-equilibration of the solid to a Ba1-xRaxSO4 solid solution and visible effects on the particle size distribution, even at room temperature.

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Contributing Institute(s):

1. Nukleare Entsorgung und Reaktorsicherheit (IEK-6)
2. Analytik (ZEA-3)

Research Program(s):

1. 142 - Safety Research for Nuclear Waste Disposal (POF2-142) (POF2-142)
2. SKIN - Slow processes in close-to-equilibrium conditions for radionuclides in water/solid systems of relevance to nuclear waste management (269688) (269688)

Appears in the scientific report 2014

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Database coverage:
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