EAGER: CET: Non-Equilibrium Plasma-Enhanced Recovery of Lithium and Critical Materials from Produced Water

This EArly-concept Grants for Exploratory Research (EAGER) award is made in response to Dear Colleague Letter 23-109, as part of the NSF-wide Clean Energy Technology initiative. Critical materials such as lithium, cobalt and magnesium are key to successfully transitioning to a green/clean and sustainable energy landscape as they are the materials/elements that form the backbone of electrical energy conversion and storage technologies. These critical materials are currently sourced through multi-national supply chains and via environmentally harmful mining processes, which impede and act as bottlenecks to U.S. sustainability and clean energy goals. The goal of this EAGER project is to investigate the potential for extraction of critical materials, specifically lithium, from a large domestic waste stream (and potential resource)- extreme salinity oil and gas produced water, using atmospheric pressure direct current (dc) non-equilibrium plasma discharges. Plasma, as one of the four fundamental states of matter, is an ionized and highly energetic state with unique properties. By tuning the plasma characteristics and environment, its interaction with a liquid and the resulting liquid-phase reactions can be tailored and controlled. The cross-disciplinary (plasma physics/chemistry, interfacial processes, transport phenomena, and electrochemistry) project will impact education as it relates to developing a competitive STEM workforce, and sustainable extraction of critical materials from domestic sources has the potential to strengthen supply chains of these materials for the energy and defense sectors, which is of vital importance for U.S. national security and energy independence. The intellectual focus of this project is to elucidate the mechanisms/pathways that facilitate precipitation of stable lithium (and other critical material) compounds from extreme salinity produced water when it is treated with dc non-equilibrium plasma discharges under atmospheric pressure conditions. The main questions that the project addresses are: (i) to what extent do the non-equilibrium characteristics of the plasma facilitate both Faradaic and non-Faradaic pathways towards precipitation of lithium (and other critical materials) from extreme salinity water, (ii) what role does the solvated electron play in this precipitation process, and (iii) can supersaturation of the liquid with solvated electrons forcibly facilitate metal reduction, even reduction of highly soluble/reactive metals such as lithium. The team will explore electrochemical and non-electrochemical pathways for precipitation of lithium compounds during plasma-liquid interactions with synthetic produced water solutions, and characterize the role of the plasma-liquid interface region in regulating these pathways. The experimental approach will leverage plasma diagnostic tools, aqueous solution metrology, and solid material characterization tools to evaluate the pathways for lithium precipitation during dc plasma treatment of extreme salinity aqueous solutions. These fundamental studies can then be leveraged to intensify lithium compound/complex precipitation from real oil and gas produced water, thus valorizing a high-volume domestic wastewater source and increasing the resiliency of domestic critical materials supply chains. 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.