Abstract
To develop a microsystem for determining the oxidation state of actinides, we tested the performance of a mm-scale continuous-flow system in measuring the change in oxidation state of Ce (III) to Ce (IV) with time using X-ray absorption near-edge structure (XANES) analysis. A 1 mM Ce (III) solution mixed with a 1 mM desferrioximine B solution (DFO) was pumped into the system, and then the solution was carried through it at a constant flow rate to the point at which the XANES spectra were captured. The system revealed the distinct peaks of Ce (III) and Ce (IV) in LIII edge Ce XANES spectra. The peak intensity of Ce (IV) increased when the reaction time after mixing the two solutions was extended, reflecting the continued oxidation state change of Ce (III) by DFO. Five XANES spectra repeated taken during the test showed no changes in the spectra, indicating the constancy of the oxidation states of Ce throughout the duration of the measurements. Measurements of XANES spectrum over longer periods in the system revealed only low fluctuations in the spectrum around the Ce (III) and Ce (IV) peaks. These results indicate that the mm-scale continuous flow system with XANES analysis is suitable for measuring changes in the oxidation state of actinides with time.
