Adsorption of U(VI) to iron oxides like goethite (αFeOOH) can control the fate and transport of uranium in subsurface environments. The U(VI)-goethite system has been widely studied as a sorbate-sorbent system with multiple surface complexation models that have been developed to interpret adsorption as a function of water chemistry. In this study a set of these models were studied to identify the variation in predicted adsorption as a function of model choice. The main driver of variation in the output was the choice of U(VI) surface complexation reactions, although the choice of equilibrium constants for aqueous reactions, the site density, and the electrostatic model type also impacted the model output. Differences in models largely arose because individual models had been parameterized using a specific dataset. To develop a more robust model, the datasets from multiple previous studies were combined into a much larger master dataset for which a global optimal set of model parameters could be determined. Fitting was performed using MINFIT. For this effort to find a globally optimal model, the equilibrium constants for aqueous reactions and the surface site density were set at critically reviewed values.

Intercomparison of surface complexation models for uranium(VI) adsorption to goethite: Sources of variation in model output and movement toward a more globally optimal model

255th National Meeting (2018)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.