A study of the surface sorption process of Cm(III) on silica by time-resolved laser fluorescence spectroscopy (I)

The surface sorption process of Cm(III) on aqueous silica colloid solutions is investigated by time-resolved laser fluorescence spectroscopy (TRLFS) t o describe pertinent surface complexation reactions of trivalent ions. The experiment is performed in a dispersion of amorphous pyrogenic silica collo ids in 0.1 M NaClO4 under exclusion of CO2 in an inert gas box. The silica concentration is varied at 0.01, 0.05, 0.15 and 0.5 g/L, while changing pH between 4 and 10. Besides the Cm3+ aquo ion and hydroxo complexes, two Cm s pecies are observed as sorbed on silica, which are characterized by their e xcitation and emission spectra and also by lifetime. In this paper the impl ications of the spectroscopic results on the binding state of Cm are discus sed.