Spray Absorption and Electrochemical Reduction of Nitrogen Oxides from Flue Gas

This work developed an electrochemical reduction system which can effectively scrub NO<sub>×</sub> from flue gas by using aqueous solution of Fe­(II)­(EDTA) (ethylenediaminetetraacetate) as absorbent and electrolyte. This new system features (a) complete decomposition of NO<sub><i>X</i></sub> to harmless N<sub>2</sub>; and (b) fast regeneration of Fe­(II)­(EDTA) through electrochemical reaction. The Fe­(II)­(EDTA) solution was recycled and reused continuously during entire process, and no harmful waste was generated. The reaction mechanism was thoroughly investigated by using voltammetric, chromatographic and spectroscopic approaches. The operating conditions of the system were optimized based on NO<sub><i>X</i></sub> removal efficiency. Approximately 98% NO removal was obtained at the optimal condition. The interference of SO<sub>2</sub> in flue gas and the system operating stability was also evaluated.