(198p) Magnetic Core Shell Microspheres for Extraction of Rare Earth Elements from Geothermal Brine Solution

Authors: 
McGrail, B. P. - Presenter, Pacific Northwest National Laboratory
Liu, J., Pacific Northwest National Laboratory
Rare-earth elements (REEs) have significant commercial uses in the high-tech sector. However, difficulties associated with REE extraction in the conventional mining process has resulted in the search for REEs from alternative resources in a cost effective, environmentally-friendly manner. Among various sources, geothermal brine, used for generating geothermal energy was found to possess high concentration (~ppm level) of REEs in +3 ionic forms along with other dissolved metal ions. A system that can selectively trap the REEs using the existing setup of a geothermal power plant will lead to an additional revenue stream that will accelerate the development and deployment of geothermal plants in the United States and the rest of the world. Here, i present a magnetic core-shell approach that can effectively extract REEs in their ionic form from aqueous solution with up to 99.99% removal efficiency. The shell, composed of thermally and chemically stable metal-organic frameworks (MOFs) surrounds a Fe3O4 magnetic core. Majority of the Fe2+ species of the magnetite (Fe3O4) microsphere is oxidized to Fe3+ species (maghemite) during in-situ coating of the MOF materials as evident by magnetometry, Mössbauer spectroscopy, and X-ray absorption spectroscopy. The core-shell particles can be completely removed from the mixture under an applied magnetic field, offering a practical, near-term efficient REEs-removal process.