The broader impact of this SBIR Phase I project is through a compact and efficient means of mitigating atmospheric pollution of sulfur dioxide (SO2), a major human health and environmental hazard. Conventional wet scrubbers for SO2 removal are expensive to install and are highly limited by their large footprint, reducing the practicality of their implementation for mobile or space-limited applications. The proposed approach to SO2 capture uses electricity to directly remove the contaminant from a gas stream, providing significant improvements in energy efficiency and eliminating the need for caustic chemicals inherent to conventional SO2 scrubbers. The need for innovative solutions for SO2 removal is highlighted in the maritime shipping industry, where recent legislation on SO2 emissions has created an immediate need for technology that can be retrofitted into existing infrastructure on cargo vessels. This project can potentially be extended to many applications where electrical energy is supplied. The proposed method of SO2 removal uses a technique known as electro-swing adsorption (ESA), which uses a polymer-composite electrode containing an electroactive species that can capture and release a target gas through charge/discharge cycles. This technology has been demonstrated for CO2 capture, but there are significant challenges associated with developing novel chemistry for capture of SO2. Phase I research will focus on gaining a molecular understanding of the electrochemical mechanism of SO2 reactivity. The binding constant for the target gas can be ascertained as a function of the reduction potential of the electroactive species, providing a method of selecting optimized candidates for SO2 capture that are highly reactive and selective over other gases present in exhaust streams, such as CO2. The absorption capacity of the electroactive species will also be assessed using packed-bed absorption columns to simulate an electro-swing adsorption device. 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.
