Colloid / interfacial chemistry
Influence of inorganic and organic colloids on the migration behavior of radionuclides
The radionuclide migration is studied in the frame of a repository safety assessment under best possible natural conditions and in well-defined systems (bottom-up approach). The influence of colloidal / nanoscale phases as well as of redox processes on the radionuclide solubility and the migration behavior is of major interest. The aim of our group is
- to define the relevant end-storage-specific areas of colloid formation ("self" colloids, pseudo-colloids from host rock, pseudo-colloids from secondary phase formation),
- to determine the stability behavior of inorganic and organic colloids as a function of geochemical parameters (pH, EH, ionic strength, DOC) and over long time periods,
- to perform laboratory and underground laboratory experiments for the quantification of colloid mobility and their interaction with natural mineral surfaces, and
- to elucidate the thermodynamics and kinetics of the colloid interaction with radionuclides.
The molecular and macroscopic process understanding based on this work is used to develop physicochemical models and / or to extend existing ones. These models enable a prediction of colloid stability and the relevance of colloids for radionuclide migration under natural geochemical conditions.
The work is supplemented by experiments in the underground laboratory Grimsel (GTS, Switzerland), in which the influence of colloidal phases on the radionuclide migration in the real system is investigated.
Specific analysis methods for the characterization of nanoparticles and colloids and their radionuclide interaction are used:
- Size fractionation: UC, AsFlFFF or SEC on-line coupled with UV-VIS, MALLS, LIBD or ICP-MS; CE-SF-ICPMS, AMS-RIMS, PCS
- Microscopy: ESEM, STEM-HAADF ,
- Spectroscopy: XRD, XAFS, NMR, TRLFS, STXM, ...).
These analytical methods are further developed and adapted to the specific problems.
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