(391e) Electrochemical Direct Air Capture Using Neutral Red As an Oxygen Insensitive Redox-Active Molecule: System Design and Performance

Carbon capture and storage is a collection of techniques that capture CO₂ from large emission sources or from the atmosphere and safely stores it underground or in products. Carbon capture and storage is a versatile technology that enables both emission mitigation from industry as well as CO₂ removal via direct air capture.

The electrochemical direct air capture using organic dye compound, neutral red/leuco-neutral red (NR/NRH2), as an oxygen insensitive redox-active molecule uses electrochemical potentials to modulate pH of water to achieve CO₂ separation from ambient air. A preliminary system was assembled to demonstrate separation using 15% CO₂ and ambient air in a batch and continuous flow system, designed to evaluate carbon capture efficiency and system integrity.

To obtain better energy analysis, a cyclic flow system was built to study the performance at different current densities, liquid flow rates, electrochemical cell design, and electrode materials, using 15% CO₂. The current and voltage responses of the electrochemical process in a cyclic flow setup will be discussed under various electrochemical conditions. The integrated electrochemical system under the optimized condition was tested for direct air capture in a cyclic flow system.

The demonstrated electrochemical direct air capture system using NR/NRH2 at high electron utilization and moderate electrical energy consumption will encourage future research into optimizing the electrochemical separation unit for long-term and stable operations in large-scale applications.