(656b) Recovering Rare Earth Elements from Brine with Two-Dimensional Functional Materials

Rare earth elements (REEs) are critical for manufacturing a range of products. To address the growing demand, it is important to build domestic production capability for them. REEs commonly exist in various brine sources but with very low concentration, typically ppb to ppm level. Highly selective adsorbents capable of facile uptake are desirable for recovering REEs from brines. A few peptides with sophisticatedly designed structures have demonstrated exceptional REE adsorption uptake and selectivity over competing ions. However, the sophisticated structures for the peptides mean high cost for the adsorbents. In this work, we will explore the possibility of applying cheap amino acid-containing two-dimensional (2D) materials for REEs recovery. 2D materials have the advantage of a high specific surface area, which is also highly accessible. With rich surficial amino and carboxyl functional groups like in peptides, the amino acid-containing 2D materials could potentially achieve high selectivity towards REEs if the microstructure is tuned properly. In our preliminary work, the 2D materials achieved excellent REE adsorption selectivity over monovalent metal ions, good selectivity over bivalent metal ions and moderate selectivity towards trivalent metal ions. A few different amino acids have been incorporated into the 2D materials. The materials will be evaluated for the adsorption properties for a few interested REEs and common competing ions. Detailed characterization of their physical and chemical properties will be used to understand the influence from the microstructure and chemistry of the 2D materials on their metal ion adsorption properties. This work investigates the structure-property correlation for amino acid-containing 2D materials and is very meaningful for a critical separation issue.