Influence of Humic Acid on U(VI) Sorption onto Kaolinte: Studies Using Extended X-ray Absorption Fine Structure Measurements and Time-Resolved Laser-Induced Fluorescence Spectroscopy.

Understanding the migration behavior of actinides is important for the reliable long-term risk assessment of potential nuclear waste repositories. Depending on geochemical conditions different materials and processes can influence the behavior of such pollutants in natural aquifer systems. Humic acids (HA) comprise an important part of natural organic materials. HA are soluble in the pH range of natural waters and have the ability for complex and colloid formation. Due to these properties HA can affect the speciation of actinide ions, and therefore, their migration in the environment.
In the present study results from our previous batch experiments (1) were combined with spectroscopic measurements to obtain molecular-level information on the interaction of U(VI) with HA and kaolinite in natural systems.