Sustainable Electrochemical NO Capture and Storage System Based on the Reversible Fe²⁺ /Fe³⁺-EDTA Redox Reaction

The removal of nitric oxide (NO), which is an aggregation agent for fine dust that causes air pollution, from exhaust gas has been considered an important treatment in the context of environmental conservation. Herein, we propose a sustainable electrochemical NO removal system based on the reversible Fe²⁺ /Fe³⁺-ethylenediamine tetraacetic acid (EDTA) redox reaction, which enables continuous NO capture and storage at ambient temperature without the addition of any sacrificial agents. We have designed a flow-type reaction system in which the NO absorption and emission can be separately conducted in the individual reservoirs of the catholyte and anolyte with the continuous regeneration of Fe²⁺-EDTA by the electrochemical reduction in Fe³⁺-EDTA. A continuous flow reaction using a silver cathode and glassy carbon anode showed that the concentrations of Fe²⁺ and Fe³⁺-EDTA in the electrolyte were successfully maintained at a 1:1 ratio, which demonstrates that the proposed system can be applied for continuous NO capture and storage.