CAREER: Beyond size and charge: leveraging electronic structure properties towards precise, programmable ion separations

Water often contains dissolved ions. They are atoms or molecules that bear electric charge. Seawater contains sodium and chloride ions. Industrial wastewater, groundwater, and water produced by fossil fuel extraction contain many other ions. Technologies to separate ions from these water sources can provide freshwater, remove pollutants, and improve manufacturing processes. Some of the ions include critical minerals or rare earth elements. Recovering these ions could help build resilient supply chains for manufacturing batteries, electric motors, and semiconductors. Water filtration uses membranes that separate ions based on differences in size or electric charge. This CAREER project will integrate theory and experiments to demonstrate separation based on the electronic structure properties of ions, which could enable separation of ions of similar size. Results will improve ion separation processes for applications of industrial and national importance. In addition, the will train students and practicing engineers to develop innovative water treatment technologies. This project will combine theoretical development with experimental characterization of ion-permeable filters called membranes. First, it will extend current theoretical models of ion transport by treating ions as “soft spheres” that can overlap according to their electronic structure properties. This is a significant improvement over current models that treat ions as “hard spheres” which cannot overlap. This new model will make it easier to explain why different ions move through membranes at different rates. The insights will improve future membrane design. Second, the project will explore two approaches to create “dynamically-tunable” membranes. These are membranes whose ion permeability can be adjusted using external electric and/or magnetic fields. One approach will develop membranes that can conduct electricity. Applying voltage to the conductive membrane will change the relative permeability of different ions according to their electronic structure properties, thus increasing or decreasing the filtration rate of target ions. The second approach will investigate whether external electromagnetic fields make certain ions move through a membrane more easily. Together, these two approaches will establish foundational knowledge to create rapidly-adjustable, precise ion filtration processes. The project also includes educational and outreach activities such as hands-on undergraduate projects, a graduate course, and continuing education modules. These activities will help professional engineers and engineering students evolve for the challenges of the 21st century. Together, the integrated research and educational activities to be conducted will contribute to increasing economic competitiveness and national defense and support the development of a globally competitive STEM workforce in the United States. 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. NSF Award ID: 2542570 | Program: 01002627DB NSF RESEARCH & RELATED ACTIVIT | Principal Investigator: Ryan Kingsbury | Institution: Princeton University, PRINCETON, NJ | Award Amount: $650,000 View on NSF Award Search: https://www.nsf.gov/awardsearch/show-award/?AWD_ID=2542570 View on Research.gov: https://www.research.gov/awardapi-service/v1/awards/2542570.html