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.

Hydroxyapatite and Titanium Dioxide Nanoparticles: Radiolabelling and In Vitro Stability of Prospective Theranostic Nanocarriers for 223Ra and 99mTc

“…Targeted alpha therapy using TiO 2 was already studied by its 225 Ac-radiolabelling [ 8 ] and Ag-dopped TiO 2 particles by its 211 At-radiolabelling [ 35 ]. A number of studies dealing with uranium and uranyl salts sorption on TiO 2 describe its beneficial impact for long-term storage as an extra barrier for radionuclide sorption for radioactive waste repositories [ 36 , 37 ].…”

Adsorption of gluconate and uranyl on C-S-H phases: Combination of wet chemistry experiments and molecular dynamics simulations for the binary systems

“…As reported byTits et al (2011), the addition of U(VI) does not greatly affect the equilibrium state of C-S-H phases. Three main sorption species were identified byTits et al (2015): a surface complex, incorporated species, and a surface precipitate. A slight increase in Ca concentration with the increase of U(VI) initial concentration may be caused by Ca-U(VI) exchange on the sorption sites of the C-S-H surface.…”

Rational Design of a Uranyl Metal–Organic Framework for the Capture and Colorimetric Detection of Organic Dyes

“…Decay times on the order of 10 −4 s are consistent with the uranyl excited state, [21] whereas the minor, longer‐lived component is typical of ligand‐based phosphorescence. While uranyl‐based emission typically exhibits monoexponential decay, [22] the two component decay observed here is attributed to the presence of multiple emissive centers owing to the four crystallographically unique uranyl sites. Finally, at 298 K the lifetime associated with the 521 nm emissive peak is triexponential and on the order of 10 −6 to 10 −7 s. This is wholly consistent with the presence of a temperature mediated quenching mechanism.…”