Mechanisms of uranyl and phosphate (co)sorption: Complexation and precipitation at α-Al2O3 surfaces

TRLFS Evidence for Precipitation of Uranyl Phosphate on the Surface of Alumina: Environmental Implications

“…Moreover, using techniques sensitive to U present at the trace levels on the Al-oxide is necessary, since it was suggested that the loading of the surface with P and U is the key parameter controlling the transition between ternary surface complex and U(VI)-phosphate surface precipitates. 6 In this work, we examined the effect of phosphate ligands on the chemical speciation of uranyl sorbed at low pH (3.3) and at the trace levels (∼ 0.4À4 μmol 3 g À1 ) on R-alumina. We used a spectroscopic technique that is highly sensitive to sorbed U, namely time resolved laser-induced fluorescence spectroscopy (TRLFS).…”

“…They reported the existence of surface precipitates of U(VI)-arsenate for high solution concentrations of U (g50 μM). Galindo et al 6 have studied by in situ attenuated total reflectance fourier transform infrared (ATR-FTIR) spectroscopy the dynamics of phosphate ions at the R-aluminaÀsolution interface, during the process of sorption at low pH of aqueous uranyl (1À10 μM) and phosphate ligands. They showed that surface precipitates of U(VI)-phosphates were forming for the weak concentration and the low surface area (S A < 1 m 2 .L À1 ) of R-Al 2 O 3 used in ABSTRACT: We studied the ligand-enhanced sorption of uranyl ions (1À12 μM) on R-alumina colloids suspended in (and pre-equilibrated with) solutions at various concentrations of phosphate ions (P T = 0À900 μM).…”

Sorption Properties of a Bentonite Based Material for Removal of Uranium from Alum Shale Leachate

“…The sorbent was saturated with approximately 50% of the volume passed through the column for pH 7.5. Such behavior can be explained by the species of U 6+ in solution and the presence of other inorganic ligands such as sulphate, carbonate and phosphate [23][24][25][26]. Moreover, the competition of U 6+ for sorption sites with SO 4 2-ions (from the alum shale as shown in Table 1) is higher at lower pH values.…”

“…Competition for sorption sites is thus enhanced and does have an impact in the U 6+ removal capacity. Such effects could be attributed to anions (carbonates and phosphates) [23][24][25][26], cations (e.g. Ba…”

Mutual effects of copper and phosphate on their interaction with γ-Al2O3: Combined batch macroscopic experiments with DFT calculations

“…The enhancement of adsorption formation of cation-anion-surface ternary complexes have also been proposed for the interaction of U(VI) (∼1 M to ∼10 M) with phosphate (130 M) on goethite, and U(VI)-phosphate precipitation is proposed for the interaction of U(VI) (∼100 M) with phosphate (130 M) on goethite [24]. Galindo et al [25] studied the characterization of uranyl/phosphate/␣-Al 2 O 3 systems by using electrophoretic and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. The results suggested that the enhancement of uranyl sorption on ␣-Al 2 O 3 in the presence of phosphate was attributed to both surface complexation and surface precipitation.…”