K. Sato and K. Numata
Abstract—Two years having passed since the nuclear crisis at
Fukushima, radioactive 137Cs with the half-life of ~ 30 years has
come to the forefront of our largest concern. To gain an insight
into current unsuccessful 137Cs decontamination from soil,
heavily adhesive Cs adsorption, referred as specific Cs
adsorption here, is highlighted for the layered clay minerals.
Beside the interlayer Cs+ cations, a population of Cs is able to
adsorb on the surfaces of open nanospaces with their sizes of ~
0.3 nm and ~ 0.9 nm, which are formed by one- and two-clay
nanosheet insertion into interlayer spaces. They are adsorbed
on the surfaces of both the open nanospaces so strongly that
cannot be removed even by the hydrochloric acid solution of pH
1.0, these open nanospaces thus acting as the specific Cs
adsorption site. The characteristic local molecular structures as
a clay-nanosheet edge and a wedge-shaped frayed part available
in the open nanospaces are responsible for the specific Cs
adsorption. Radioactive 137Cs that is not cleaned up after the
decontamination work would originate from the specific Cs
adsorption clarified here. The present findings unambiguously
provide the molecular evidence of specific Cs adsorption and
are thus of importance for further sophisticated
decontamination of the radioactive Cs from the soil
environment.
Index Terms—Clay mineral, positronium, radioactive Cs, soil
environment.
The authors are with Department of Environmental Sciences, Tokyo
Gakugei University, 4-1-1 Koganei, Tokyo 184-8501, Japan (e-mail:
sato-k@u-gakugei.ac.jp; m121817m@st.u-gakugei.ac.jp).
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Cite:K. Sato and K. Numata, "Study of Heavily Adhesive Cs in Soil Environment," International Journal of Environmental Science and Development vol. 4, no. 6, pp. 628-632, 2013.
