Eu(III) transfer in single N,N,N’,N’-tetraoctyldiglycolamide-impregnated polymer-coated silica particle using fluorescence microspectroscopy: transfer mechanism and effect of polymer crosslinking degree

A microcapillary manipulation system combined with fluorescence microspectroscopy enabled us to analyze mass transfer in a single particle. In this study, we revealed the Eu(III) distribution in a single diglycolamide-derivative extractant (TODGA)-impregnated polymer-coated silica particle. The reaction of Eu(III) with two TODGA molecules in the polymer layer was the rate-limiting process, which was revealed by the relationship between the rate constants ( k 1 and k -1 ) and concentrations of Eu(III) and HNO 3 . The decrease in the crosslinking degree of the polymer layer caused an increase in only k -1 . This indicates that hydrophilic environments at lower crosslinking degrees enhance the stability of the charged Eu(III) species such as Eu 3+ , Eu(NO 3 ) 2+ , and Eu(NO 3 ) 2 + . Graphical abstract