Abstract
In Belgium, the Boom Clay is studied aso ne of the potential host rocks
for the geological disposal of radioactive waste. The clay minerals
within the Boom Clay contribute significantly to the retardation of the
release of radionuclides from the potential repository to the geosphere
and biosphere due to their sorption capacity. The major processes
responsible for this behaviour are cation exchange in the interlayer of
(mostly) swelling clays like smectites, and surface complexation on the
broken edges of clay platelets (Baeyens and Bradbury, 1997; Bradbury and
Baeyens, 1997; 2000). Due to these processes, clay minerals also
dictate to a high extent the pore water chemistry of argillaceous rocks
(Bradbury and Baeyens, 1998). Besides a high sorption capacity, clay
minerals may equally possess substantial reduction-oxidation potential,
depending on their nature and Fe content (Neumann et al., 2011). Several
naturally-occurring mechanisms have already been identified which are
able to alter the Fe(II)/Fe(III) content of clay minerals (Schaefer et
al., 2011), thereby changing both their redox behaviour as well as their
layer charge and as such their total adsorptive capacity (Gorski et
al., 2013). Novel electrochemical methods were developed to probe the
total electron-accepting and electron-donating capacity of clay
minerals, based on kinetic probes (Neumann et al., 2008; Gorski et al.,
2011). The detailed study of the clay mineral characteristics is
therefore fundamental in our understanding of the Boom Clay composition
and geochemical processes, and forms the base for further experimental
work and modelling. The objectives of this PhD are to study the clay
mineral characteristics of various Boom Clay samples, both qualitatively
and quantitatively, and to couple this information to geochemical
parameters and processes. This coupling would allow to gain a better
insight into the retention properties of Boom Clay towards radionuclide
dispersion starting from baseline mineralogical information.
Original language | English |
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Qualification | Doctor of Science |
Awarding Institution |
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Supervisors/Advisors |
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Date of Award | 7 Feb 2020 |
Publisher | |
State | Published - 7 Feb 2020 |