Computational Studies for Optimization and Design of Extracting Agents for Separation of Lanthanides and Actinides

Rare earths and actinides are of great interest given their varied applications in energy conversion and storage, such as in catalysis and batteries, and for advanced technological applications related to optical and magnetic properties (including electronics and automotive), amongst others. Many of the rare earth elements are considered endangered species due to their unique properties which have no clear alternatives that will maintain performance for important applications. The optimal approach is to find readily available alternatives for critical materials to ensure a certain standard of living and quality of life for future generations, but it is very likely that reusing and recycling of endangered elements will be required. Computational methods are a key component in the search for less costly separation processes and in optimizing known separation methods, which could ultimately lead to reusing and recycling endangered elements, and for finding alternatives for critical materials.

Optimization of separation processes is needed not only for separations of rare earths, but also for separations of actinides. Separating uranium from seawater has recently become an area of interest due to the large amount of uranium found in seawater, which exceeds the amount found on the Earth’s crust. Actinide separation is also required in the processing of radioactive waste, and is therefore necessary to fully realize the contribution of nuclear energy to an economy based on clean energy.

Computational techniques can be enormously helpful in optimizing and designing separation agents to aid in the separation process of lanthanides and actinides. The chapters included in this dissertation seek to contribute to the understanding of complexation of lanthanides and actinides with different complexing agents, through in-depth computational studies. The material presented in Chapter II focuses on contributing to the understanding of the mechanism involved in solvent extraction of lanthanides with carboxylic acids. In particular, Chapter II studies possible conformations involved in the formation of the coordination shell and the determination of preferred coordination numbers. Chapter III studies effects of beta diketones with different substituents as extracting agents. Chapter IV focuses on providing better understanding of selective extraction of uranium, neptunium, plutonium, and americium with imide dioximes.