Molecular Modeling Investigation of Cation Siting in Crystalline Silicotitanate and Polyoxoniobate Materials
Year: 2004
Type: article
Abstract: Separation of radionuclides from high-level nuclear waste solutions is a vital step to minimize the amount of nuclear waste volume for final disposal. A number of inorganic ion exchangers have demonstrated the ability to selectively remove low concentrations of radionuclides in the presence of high sodium ion content and alkalinity. Various classes of crystalline silicotitanates (CST), pharmacosiderates and polyoxoniobates are being synthesized by collaborators at Texas A&M and Sandia National Laboratories. The ion exchange performance of these materials may be improved by introducing suitable structural modifications, such as partial substitution of niobium for titanium in the framework structures. In this work, the origins of ion exchange selectivity and kinetics are investigated through atomistic level simulations. The primary focus has been to develop a transferable potential model that can be used to accurately predict structural characteristics of the ion exchangers o f interest. Energy minimizations and molecular dynamics simulations are applied to the CST and polyoxoniobate materials. Structural characteristics, such as cation and water sites, coordinating environments and the energetics associated with the sites are determined, providing additional molecular-level insight into the stability of the structures.
Authors: Edward J. Maginn, James P. Larentzos
Language: English
Subfield: Waste Management and Disposal
Field: Environmental Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W1588527037