Sorption Mechanism of Europium by Apatite Using Rutherford Backscattering Spectroscopy and Resonant Nuclear Reaction Analysis.

Abstract

A sorption mechanism of Eu, an analog of trivalent TRU, on apatite has been studied based on the depth profiles obtained by Rutherford backscattering spectroscopy (RBS) and resonant nuclear reaction analysis (RNRA). A positive peak for Eu and a negative peak for Ca were observed in an RBS spectrum obtained by subtracting fresh apatite one from a Eu-sorbed apatite one. This indicates that at least part of Eu was sorbed on the apatite, while a fraction of Ca was released from the apatite. The peak height for Eu in the RBS spectrum of apatite increased with increase in temperature of the sorption experiments. The depth profiles of hydrogen of the Eu-sorbed apatites were similar to that of fresh apatite. This indicates that amount of Ca exchanged for hydrogen is very low. In the sorption experiments the concentrations of Eu in the solutions decreased with increase in the temperature. On the contrary, the concentrations of Ca increased with increase in the temperature. Thus, it is concluded that a fraction of ...