Study on cooperative removal of NOx in simulated flue gas by paired electrolysis

Abstract

A paired electrolysis technology was introduced to build two-stage oxidation and absorption equipment for cooperative and highly efficient removal of NOx in simulated flue gas. The oxidant yield and NOx removal efficiency in four electrolysis systems were compared. Meanwhile, a series of process parameters were optimized including current density, cathode-anode area ratio, NaCl concentration of anode electrolyte, air flow rate in cathode chamber, inlet NO concentration and gas flow rate. The results showed that two oxidants containing available chlorine (AC) and H2O2 were produced respectively during the period of paired electrolysis. Firstly, the AC produced by anode oxidized NO to NO2, then surplus NO was further oxidized by the cathode product H2O2. Finally, the oxidation product was substantially absorbed by alkaline cathode electrolyte. The highest NOx removal efficiency of 95.6% was achieved by paired electrolysis system under optimal conditions. It provided a facile strategy for high efficient electrochemical removal of NOx.