Using a High-Throughput Screening Algorithm and relativistic Density Functional Theory to Find Chelating Agents for Separation of Radioactive Waste

TL;DR

This study combines high-throughput screening and relativistic DFT to design novel chelating agents for separating actinides in radioactive waste, demonstrating a faster discovery process and tunable selectivity.

Contribution

It introduces an integrated computational approach to rapidly design and optimize chelating agents with enhanced selectivity for actinide separation.

Findings

Identified linkers that improve complex stability and selectivity.

Demonstrated the effectiveness of combining high-throughput algorithms with relativistic DFT.

Showed that secondary coordination sphere modifications influence actinide binding.

Abstract

Dangerous radioactive waste leftover from the Cold War era nuclear weapons production continues to contaminate sixteen sites around the United States. Although many challenges and obstacles exist in decontaminating these sites, two particularly difficult tasks associated with cleanup of this waste are extracting and separating actinide elements from the remainder of the solution, containing other actinide elements and non actinide elements. Developing effective methods for performing these separations is possible by designing new chelating agents that form stable complexes with actinide elements, and by investigating the interactions between the chelating agents and the actinide elements. In this work, new chelating agents (or ligands) with potential to facilitate the separation of radioactive waste are designed for Th, Pa, and U using relativistic Density Functional Theory (DFT) inconjunction with a high-throughput algorithm. We show that both methodologies can be combined efficiently to accelerate discovery and design of new ligands for separation of the radioactive actinides. The main hypothesis that we test with this approach is that the strength of secondary coordination sphere (SCS) can be tuned to increase the selectivity of binding with different actinides. More specifically, we show that links that connect two of the catecholamide ligands via covalent interactions are then added to increase the overall stability of the complex. The effect of increase in the selectivity is also observed when non-covalent interaction is used between ligands. We apply this approach for Th, Pa, and U, and discover linkers that can be used with other ligands.