Influence of temperature and reducing conditions on the sorption of sulfate on magnetite.

The reactivity of aqueous sulfate toward magnetite was studied between 50 and 275 °C as a function of pH and the redox conditions. Under oxidizing conditions, we did not observe redox reactions and the sorption of aqueous sulfate is promoted under acidic conditions when the magnetite surface is positively charged. The effect of temperature on this retention is moderate but complex.

Sorption of sulfate ions onto magnetite.

In order to acquire data necessary to understand and predict the behavior of oxide particles in the secondary circuits of pressurized water reactors (PWR) and study the role of redox and interface reactions, the acid-base properties of magnetite and sorption of sulfate ions were studied at 25 degrees C. Redox reactions with magnetite predicted from thermodynamic data were not observed and sulfur species always remain as sulfate. From zetametric measurements, mass titrations and acid-base titrations an IEP at 6.

Theoretical investigation of the uranyl ion sorption on the rutile TiO2(110) face.

Canister integrity and radionuclide retention is of first importance for assessing the long-term safety of nuclear waste stored in engineered geologic depositories. Uranyl ion sorption on the TiO(2) rutile (110) face is investigated using periodic density functional theory (DFT) calculations. From experimental observations, only two uranyl surface complexes are observed and characterized.

Effect of the adsorption of lithium and borate species on the zeta potential of particles of cobalt ferrite, nickel ferrite, and magnetite.

Zetametric measurements on suspensions of oxide particles (cobalt ferrite, nickel ferrite, and magnetite) representative of corrosion products from primary circuits of pressurized water reactors were performed at 25 and 70 degrees C in the presence of lithium and borate species. No effect of lithium ions was observed. Borate species cause a decrease of the isoelectric point (IEP), attributed to the sorption of borate as a negative complex MOB(OH)3(-).

Surface complexation modeling of uranium(VI) sorbed onto zirconium oxophosphate versus temperature: thermodynamic and structural approaches.

This work presents an investigation of the interaction mechanisms between uranyl ions and a solid phosphate, the zirconium oxophosphate: Zr2O(PO4)2. Both thermodynamic and structural points of view are developed. Indeed, prior to any simulation of the retention data, it is necessary to precisely characterize the system under study in order to gain information at a molecular scale.