Conventional recovery of rare earth elements requires brute-force mineral dissolution using strong acids and bases, followed by many rounds of solvent extraction to separate the lanthanides based on their size differences. These processes render lanthanide recovery expensive, hazardous, and inefficient. The goal of our project, Dissolution by design: selective leaching of rare earth elements using SMART lixiviants, is to create a ligand that selectively coordinates between the lanthanides. Macrocycles have been investigated to fulfill this role, and several ligands have shown significant prospects. The current focus of this project is testing the capability of acyclic versions of the macrocyclic ligands experimentally tested to show selectivity. Running calculations with NWChem, we use density functional theory (DFT) to optimize the geometry of potential ligands for each lanthanide. After running a frequency calculation to confirm the optimized structure is a minimum energy conformation, we then run a solvent phase energy calculation. In addition, single point energy calculations are run with a larger basis set to get a more accurate energy. Through these calculations, we are able to compare the energy stabilities of light and heavy lanthanides with these lixiviant ligands. This talk will cover the in depth methods we use to run these calculations, and the results we have obtained so far. These ligands’ potential selectivity between the lanthanides would bring a cost effective lixiviant to the American rare earth element industry.

Lanthanide-selective lixiviants: A computational view of optimizing binding constants

Fall 2022 abstracts, posters, and presentations will launch in mid-September.

ACS Fall 2022

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