Kinetics and mechanism of Eu(III) transfer in tributyl phosphate microdroplet/HNO aqueous solution system revealed by fluorescence microspectroscopy

Miyagawa, Akihisa*; Kusano, Yuka*; Nagatomo, Shigenori*; Sano, Yuichi   ; Nakatani, Kiyoharu*

In this study, we reveal an Eu(III) extraction mechanism at the interface between HNO and tributyl phosphate (TBP) solutions using fluorescence microspectroscopy. The mass transfer rate constant at the interface is obtained from the analysis of fluorescence intensity changes during the forward and backward extractions at various HNO and TBP concentrations to investigate the reaction mechanism. This result indicates that one nitrate ion reacts with Eu(III) at the interface, whereas TBP molecules are not involved in the interfacial reaction, which is different from the results obtained using the NaNO solution in our previous study. We demonstrate that the chemical species of Eu(III) complex with nitrate ion and TBP in the aqueous solution play an important role for the extraction mechanism.