Synchrotron radiation photoemission electron microscopy analysis of clay minerals containing cesium

Yoshigoe, Akitaka 

Decontamination of Cs trapped in clays is considered to be difficult because Cs atoms tightly bind to the clays. Therefore, the development of the methods to efficiently remove Cs from polluted areas has become a matter of great importance and has motivated research into basic understanding Cs adsorption to clay and its physicochemical properties. In this study, a synchrotron radiation photoemission electron microscope (SR-PEEM) was applied to demonstrate pinpoint analysis of micrometer-sized weathered biotite clay particles with artificially adsorbed non-radioactive Cs. Despite the insulating properties of the clay, we observed the spatial distributions of constituent elements with nanometer resolution without charging issues through a proper surface treatment. Pinpoint XAS spectra indicated the chemical states of Fe and Cs. The results strongly suggest that Cs adsorption took place via electrical charge compensation mechanisms. Further technical developments are required to apply to real-world samples with extremely low Cs content; however, we succeeded the first step towards applying this method to nanoscale analysis of Cs-adsorbed clay minerals.