Modeling How Uranium Sticks to Soils

Understanding the interaction of uranium in soils may lead to new ways to clean-up contaminated ground.

Computational modeling of uranium oxide ions with aluminum oxide — Image courtesy of Pacific Northwest National Laboratory

The Science

A simple computational methodology was developed to determine how uranium adheres to aluminum oxide, a mineral in complex soil environments.

The Impact

This research provides insight into how radionuclides, like uranium, interact with soil minerals, which may lead to efficient, more affordable solutions for cleaning contaminated ground.

Summary

Determining how radioactive material sticks to soil and affects its movement into nearby water sources is a major challenge for cleaning up nuclear waste sites. This waste, which may include uranium, can be diffuse as well as difficult to isolate and remove. To reduce the cost and complexity of complete removal, innovative and inexpensive methods are needed to expedite clean-up efforts around the world, especially in sites with vast areas of contamination. Scientists at Pacific Northwest National Laboratory discovered that the surface of a common soil mineral, aluminum oxide, adheres to uranium making it less mobile. The researchers assembled a detailed picture of how uranium adheres to the mineral surface using a computational model. By modeling the behavior of uranium in a complex subsurface environment, they were able to show that uranium sticks to the surface of aluminum oxide without changing it in any way and that a more acidic environment improves how well the two stick together. This cluster model approach used by the researchers allows for a straight forward comparison to be made between different sorption mechanisms and predictions can be directly related to X-ray adsorption experiment measurements. This approach can be used to model surface reactivity and be further utilized in other complex model systems.