INDICATION OF CESIUM ADSORPTION INTO ANGSTROM-SCALE OPEN SPACES IN SAPONITE CLAY MINERAL

Abstract

Adsorption behavior of cesium (Cs) into angstrom-scale open spaces for the saponite clay mineral is investigated by making use of positronium (Ps) annihilation spectroscopy together with thermogravimetry and differential thermal analysis (TG–DTA). Ps annihilation spectroscopy reveals two kinds of open spaces with their sizes of ~ 3 Å and ~ 10 Å, respectively, after baking at 423 K for 8 h under the vacuum condition at ~ 10-5 Torr. The large open space is found to survive for the Cs -type saponite due to less hydration of the Cs cations even after the exposure to the air for 200 h. It is thus inferred that Cs is locally adsorbed in the angstrom-scale open spaces in the saponite clay minerals.