0000000000393901
AUTHOR
Daniel R. Fröhlich
Sorption of neptunium(V) on Opalinus Clay under aerobic/anaerobic conditions
Abstract The interaction between neptunium(V) and a natural argillaceous rock (Opalinus Clay (OPA), Mont Terri, Switzerland) has been investigated in batch sorption experiments by varying pH (6–10), Np(V) concentration (10−12–10−4 M), solid-to-liquid ratio (2–20 g/L), and partial pressure of CO2 (10−3.5 and 10−2.3 atm) under aerobic/anaerobic conditions in saturated calcite solution. All batch experiments were carried out using well characterized aerobic and anaerobic dry powders of OPA. The results show a great influence of pH on Np(V) sorption. Under aerobic conditions sorption increases with increasing pH until maximum sorption is reached between pH 8–9. At pH>9 sorption decreases due…
Influence of humic acid on neptunium(V) sorption and diffusion in Opalinus Clay
SummaryThe influence of14C-labeled M42 humic acid (HA) on the interaction between neptunium(V) and natural clay rock (Opalinus Clay (OPA), Switzerland) has been investigated in batch sorption and diffusion experiments under ambient air conditions. The effect of 10 mg/L HA on the diffusion of 8 μM Np(V) in OPA has been investigated in synthetic OPA pore water (pH 7.6, I = 0.4M) for the first time. Batch sorption experiments as a function of solid-to-liquid ratio (4-20 g/L) were performed under same experimental conditions to compare distribution coefficients obtained from both diffusion and sorption experiments. These experiments showed only a slight influence of HA on Np(V) uptake by OPA in…
Influence of temperature and background electrolyte on the sorption of neptunium(V) on Opalinus Clay
Abstract The temperature dependence of the sorption of 8 μM neptunium(V) on Opalinus Clay (OPA, Mont Terri, Switzerland) was investigated between 40 and 80 °C and compared to previous results for 20 °C. The batch experiments were performed under ambient air conditions in synthetic pore water (pH = 7.6, I = 0.4 M) under variation of the solid-to-liquid ratio between 2 and 20 g/L. Under these conditions the sorption of Np(V) on OPA was found to be an endothermic process as the average distribution coefficient (K d ) increases continuously with increasing temperature from 23 ± 4 L/kg at 40 °C to 678 ± 254 L/kg at 80 °C. In the temperature range of 40-80 °C, the plot of log(K d ) vs. 1/T could …