Sorption studies on Boom Clay and clay minerals - status 2016

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Abstract

For the geological disposal program in Belgium, migration studies of the radionuclides have been performed extensively at the RDD group at SCK•CEN. This report aims to give an overview of all the sorption experiments performed in the past in the framework of the geological disposal program. This means that all experiments performed on Boom Clay are included, but also on Boom Clay constituting minerals like illite and montmorillonite. A variety of radionuclides was studied having quite different chemical/sorption behaviour. For the monovalent cations, cesium (Cs) has been studied. The divalent group encompasses strontium (Sr) as earth alkaline metal and zinc (Zn) and nickel (Ni) as transition metals. For the tri- and tetravalent cations, the focus has been put on americium (Am), europium (Eu) and thorium (Th). At last, there is the group of redox-sensistive elements involving technetium (Tc), selenium (Se), uranium (U), neptunium (Np) and plutonium (Pu). Next to the radionuclides, this report includes also all the sorption experiments of natural organic matter (NOM) on illite and Boom Clay. The sorption behaviour of these radionuclides is quantified by the solid-liquid distribution coefficient. This solid-liquid distribution is conditional, i.e. only valid for the conditions of the experiment. Next to the affinity of the specific element and the binding capacity of the sorbent, different factors can influence the solid-liquid distribution. First, the sorption behaviour is very dependent of the geochemical conditions: pH, ionic strength, Eh, presence of complexing ligands/agents (carbonates, dissolved organic matter). Secondly, also the experimental conditions have an influence on the measured values: time (kinetics), concentration, solid/liquid ratio, phase separation technique (colloids). This report gives an overview of all the experimental results (excluding modeling) of the sorption experiments performed for the elements described above at a variation of conditions.

Details

Original languageEnglish
PublisherStudiecentrum voor Kernenergie
Number of pages179
Publication statusPublished - 1 Dec 2016

Publication series

NameSCK•CEN Reports
PublisherStudiecentrum voor Kernenergie
No.SCK•CEN ER-0346

Keywords

  • sorption, clays, clay minerals, Boom Clay, radionuclides, cesium, strontium, nickel, zinc, americium, europium, thorium, selenium, uranium, neptunium, natural organic matter

ID: 1892389