EPRI/WERF: Collaborative Research: Electrical percolation in flowable electrodes for energy-efficient water re-use applications

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PI Name: Kelsey Hatzell/Marta HatzellProposal Number: 1706956/1706290 There is a growing need to develop low cost and modular water reuse systems to promote optimal reclamation and treatment of discharged water from industrial, municipal, agricultural and energy generation sites. Targeting strategies that optimize water usage could significantly alleviate stresses at the core of the food-energy-water nexus. The development of new water deionization technologies which can be easily scaled to meet the decentralized demands is imperative for water sustainability. Capacitive deionization is a cost effective and low energy electrochemical approach for treating brackish water streams; however, there are fundamental limitations to this approach because the process is not continuous. In this project a novel flow-electrode-based architecture is examined as a means for both continuous and scalable deionization and energy recovery. The researchers plan to collaborate with local organizations (Georgia Intern Fellowship for Teachers and Vanderbilt School for Science and Math) in order to design an experiential curriculum on brackish water treatment to increase water literacy in the Southeast. The objective of this project is to advance fundamental understanding of the design of flowable electrode architectures for ion removal processes. The PIs plan to study the concept of flow-electrode capacitive deionization (FCDI) for water treatment. FCDI systems have three flow channels, two of which serve to transport suspended activated carbon particles, which remove or electroadsorb ions, and a center channel where the feedwater is directed. To date, few studies have explored the fundamental mechanisms which promote efficient charge transfer and storage within flow electrodes. Specifically, understanding the influence of hydrodynamics within a flowable electrode and its effect on the formation and disruption or percolation networks can potentially increase material utilization and control electrochemical penetration depths. The PIs seek to define a new theoretical framework to describe charging and electron conduction processes at the particle-particle level in order to elucidate idealized operating conditions that promote energy efficient ion removal processes. The PIs will investigate the percolation network of carbon particles in a flow electrode using computational fluid mechanics, advanced in-situ characterization, and bench scale experimentation to obtain new fundamental and applied knowledge regarding this emerging deionization technology. Direct interrogation of the electrical, mechanical and microstructural properties of flowable electrode percolation networks will be obtained through advanced synchrotron-based techniques. The work has the potential to guide the design of a new process for water purification and may have broader relevance for other environmental technologies involving energy storage, energy conversion, and desalination.