Abstract: Cost-competitive and sustainable biofuels are key to combating climate change, meeting increasing energy demand, and supporting energy independence. Affordable and low-carbon biofuels are especially important for hard-to-electrify transportation sectors, such as commercial aviation, which accounted for 10% of total U.S. transportation-related greenhouse gas (GHG) emissions in 2019. Currently, biorefinery economics are driven by separations, which can account for up to 70% of bioprocessing costs. As an alternative to conventional thermal-based methods, capacitive deionization (CDI) is based on reversible electrosorption of charged species from aqueous solution.

This work focuses on development of CDI as a reagent-free and cost-effective method for selective separation and recovery of aqueous organic species (e.g., carboxylates) using activated carbon cloth electrodes. Performance metrics, including butyrate adsorption and desorption capacities, adsorption and desorption rates, charge efficiency, energy consumption, and recovery will be presented. This study also characterizes the long-term operational stability of the system by cycling the cell 1,000+ times and evaluating physical properties of the electrodes. Overall, this work informs the development of a new separation platform for the selective separation of organic species to provide concentrated, clean intermediates from which biofuels and bio-based chemicals can be manufactured.