Radiocesium sorption on illite and

Kinetics and Reversibility of Radiocesium Sorption on Illite and Sediments Containing Illite... 

The kinetics and reversibility of radiocesium sorption on illite and natural sediments have been reviewed and interpreted in terms of a mechanistic framework. This framework is based on the premise that radiocesium is almost exclusively and highly-selectively bound to the frayed particle edges of illitic clay minerals. It is shown that in-situ Ko of radiocesium in sediments are consistent with this ion-exchange process on illite. 

It is important to realise that the above models should not be used to predict Cs-sorption reversibility over time frames of more than a few months. Observations that radiocesium, which has been in contact with contaminated sediments for many years, can still be mobilised by enhanced ammonium concentrations (3,4) give evidence for a backwards reaction. This reaction, which is interpreted as a remobilization of radiocesium from fixed edge-interlayer sites on illite (i.e. box Z in Figure 5), is apparently too slow to be observed in laboratory experiments of many weeks. Therefore, extractions of radiocesium from historically contaminated sediments have been used, and are described below, to obtain a first estimate of this slow remobilization rate. 

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