title: A luminescence line-narrowing spectroscopic study of the uranium(VI) interaction with cementitious materials and titanium dioxide.
abstract: Non-selective luminescence spectroscopy and luminescence line-narrowing spectroscopy were used to study the retention of UO2(2+) on titanium dioxide (TiO2), synthetic calcium silicate hydrate (C-S-H) phases and hardened cement paste (HCP). Non-selective luminescence spectra showed strong inhomogeneous line broadening resulting from a strongly disordered UO2(2+) bonding environment. This problem was largely overcome by using luminescence line-narrowing spectroscopy. This technique allowed unambiguous identification of three different types of UO2(2+) sorbed species on C-S-H phases and HCP. Comparison with spectra of UO2(2+) sorbed onto TiO2 further allowed these species to be assigned to a surface complex, an incorporated species and an uranate-like surface precipitate. This information provides the basis for mechanistic models describing the UO2(2+) sorption onto C-S-H phases and HCP and the assessment of the mobility of this radionuclide in a deep geological repository for low and intermediate level radioactive waste (L/ILW) as this kind of waste is often solidified with cement prior to storage.
authors.affiliation: Laboratory for Waste Management, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland. jan.tits@psi.ch.
authors.forename: Jan
authors.initials: J
authors.lastname: Tits
authors.forename: Clemens
authors.initials: C
authors.lastname: Walther
authors.forename: Thorsten
authors.initials: T
authors.lastname: Stumpf
authors.forename: Nathalie
authors.initials: N
authors.lastname: Macé
authors.forename: Erich
authors.initials: E
authors.lastname: Wieland