NSF Award
2327527
Rare-earth elements (REEs) are critical materials to many leading-edge technologies that underlie clean energy transportation, energy generation and storage, communication, and computing. The availability of REEs is of special concern due to the lack of adequate U.S. domestic production. REEs enrichment in minerals in highly weathered environments represents a promising opportunity for future exploration. However, major knowledge gaps exist in our understanding of the fundamental geochemical controls on REEs accumulation in secondary minerals like clays and iron/aluminum (hydr)oxides (common products of rock weathering), especially the mechanisms of how REEs bind to and are mobilized from mineral surfaces. This project seeks to obtain the foundational scientific knowledge on REEs interactions with oxide minerals, which is required to accurately predict the occurrence and formation of REEs deposits via rock weathering and could be informative in new ways to extract these critical materials. Of equal importance will be the direct involvement and training of students at multiple levels from high school to graduate students to attract the potential next generation of scientists into STEM disciplines.<br/><br/>The effects of oxide mineralogy on the sorption mechanisms of REEs could play important roles in controlling REE fate in weathering environments but are poorly understood. This project will reveal these previously unrecognized factors using iron oxides as the model system. The overall goal is to elucidate how mineral structure, crystallinity, morphology, and interfacial structure dynamics could affect REEs sorption reactions at mineral-water interfaces. Light REEs will be used as the probing elements and an integrated series of laboratory wet chemistry experiments and synchrotron-based X-ray techniques will be employed on both iron oxide particles and hematite single crystals to accomplish the research objectives. The proposed study will obtain insight into fundamental geochemical processes controlling the formation of these critical element deposits during rock weathering processes.<br/><br/>This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
