Development of a Composite Non-Electrostatic Surface Complexation Model Describing Plutonium Sorption to Aluminosilicates

LLNL SFA FY11 Program Management and Performance Report: Environmental Transport of Plutonium

“…This was verified for FA (data not shown) and is consistent with anionic functional groups of FA interacting with positively charged gibbsite sites at low pH and being repelled by negatively charged sites at higher pH. (Powell et al, 2008 andZimmerman, 2010).…”

“…Previous experiments have shown nearly complete sorption of Pu(IV) to the mineral phase in ligand-free systems above pH 4 (Zimmerman, 2010;Powell et al, 2008). The data presented in Figure B1 shows that the presence of FA, DFOB, and citric acid causes an increase in aqueous Pu concentrations and a decrease in the Pu fraction sorbed relative to FA free systems.…”

Environmental Transport of Plutonium: Biogeochemical Processes at Femtomolar Concentrations and Nanometer Scales

“…Previous experiments have shown nearly complete sorption of Pu(IV) to the mineral phase in ligand-free systems above pH 4 (Appendix, POWELL et al, 2008). The data presented in Figure B1 shows that the presence of FA causes an increase in aqueous Pu concentrations relative to FA free systems.…”

“…Modeling efforts will be undertaken in FY11 to predict the sorption data by combining the aqueous speciation constants determined in this work and published surface complexation constants (POWELL et al, 2008). Ongoing studies with Pu-citric acid-gibbsite systems for which Pu-citric acid aqueous complexation constants are available indicate that the combination of the binary (ligand-Pu and mineral-Pu) thermodynamic constants can successfully predict the sorption behavior observed in batch tests.…”

“…To date our experiments have focused on Pu sorption to gibbsite (Al(OH) 3 ). This has allowed the research group to take advantage of a surface complexation database previously developed by the Clemson research team (POWELL et al, 2008). A new source of gibbsite was used in these experiments so a representative sorption edge was generated for Pu(IV) and Pu(V) to compare with the previous data.…”