NSF Award
2402669
This Research Advanced by Interdisciplinary Science and Engineering (RAISE) award is made in response to Dear Colleague Letter 23-109, as part of the NSF-wide Clean Energy Technology initiative. Globally, Rare Earth Elements (REEs) continue to be among the most important materials for clean energy technologies; in particular Nd, Pr, Dy, and Tb, continue to be critical for the electrified economy. REE recycling from end-of-life devices holds tremendous and growing promise, as magnets within them are rich in highly desired REEs and do not contain undesired REEs. A major unmet challenge is the need for a green, distributed method to efficiently extract and selectively separate desired REE cations from mixtures generated by dissolution of the magnets. The project will study rare-earth element (REE)-Selective Protein-hydrogels to Enable Cation Trapping (REESPECT) for scalable, distributed, continuous REE recovery processes to meet the rapid growth in REE demand to support the green economy. The REESPECT platform is based on hydrogels formed from engineered alpha-synuclein fibrils that contain selective REE binding loops to capture and separate REE from aqueous streams. The hydrogels will be formed into beads used in packed beds to allow high capacity and selective capture of REEs over non-REE cations, as well as discrimination among specific REEs. In addition to the potentially transformative impact on REE recovery and providing educational experiences for doctoral students, the project’s outcomes will be leveraged for STEM outreach and undergraduate educational initiatives. For example, demonstrations for Philly Materials Day and NanoDay will be developed. High school students will work with PhD students in the summer outreach program Penn LENS. Undergraduate researchers will be recruited from Penn and from other universities, particularly the University of Puerto Rico, for summer programs such as NSF REU. Graduate students will volunteer for Penn GEMS, a STEM outreach program for middle school students, among others. The team will develop as an undergraduate analytical chemistry lab component based on this research and will develop projects for the CBE engineering design course offered to students interested in technical solutions to problems of broad societal significance.<br/><br/>REESPECTs (Rare Earth Element-Selective Protein-hydrogels to Enable Cation Trapping) are hierarchically assembled hydrogel materials based amyloidogenic proteins in which selective rare earth element (REE) binding loops, termed lanthanide binding tags (LBTs), are presented with exceptionally high density throughout the 3-dimensional hydrogel volume. REESPECT hydrogel beads will be fabricated and fundamentally characterized for binding capacity and transport. REESPECT beads will be exploited in proof-of-concept microfluidics separation processes that can be scaled and are suitable for distributed processing. The REESPECT platform is modular; LBTs for selective separation of particular REE identified by machine learning (ML) approaches will be identified and incorporated in REESPECT for recovery and purification of highly desired REES, including Nd, Pr, Dy, and Tb. This research is highly cross disciplinary and relies on the synergistic interactions at the interface of computational protein design; amyloid protein biophysics and genetic engineering; (bio)inorganic characterization of components and structures for selective cation-binding/triggered release; development of microfluidics/confocal fluorescence microscopy assays, and proof-of-concept separations. The project will address the following four intellectual questions: (1) Is the REEESPECT platform truly modular, allowing incorporation of ML-designed LBTs with tailored REE selectivity (Aim 1)? (2) What are optimal designs for LBT binding structures to confer selectivity and effective separation between REEs, as guided by coordination chemistry and advanced ML methods (Aim 1)? (3) How do the densities of LBT presentation and hydrogel crosslinking alter REE binding along amyloid fibers (Aim 1) and binding capacity and transport under flow within REESPECT beads (Aim 2)? (4) What are optimal conditions for REE recovery and separation under flow of REE-rich streams in the presence of competing non-REE cations (Aim 3)? The REESPECT platform is designed to provide a green, all-aqueous, scalable, distributed, continuous process with the potential to transform REE recovery.<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.
