Simultaneous desulfurization and denitrification by electrodialysis

Abstract

In recent years, simultaneous desulfurization and denitrification technology has gradually become a research hotspot at home and abroad. The purpose of this paper is to study simultaneous desulfurization and denitrification of electrodialysis/Fe(II) system. In order to study the electrochemical effect on simultaneous desulfurization and denitrification by electrodialysis, simultaneous purification experiments on SO2, NO2 and NO were carried out under the conditions of electrification and non-electrification respectively. The purification effects of electrodialysis/Fe(II) system on SO2, NO2 and NO were investigated. The results show that the simultaneous purification of SO2 and NOx is inhibited by each other when no power is applied, mainly because of the competition between Fe (II) and O2. The synergistic effect between SO2 and NOx occurs after charging. The desulfurization product SO32− is reduced to S and S2− in the cathode. The system enhances the purification effect of SO2 and NOx through the oxidation-reduction cycle of S2− in the cathode. After that, the effects of oxygen content, current and Fe (II) content on desulfurization and denitrification efficiency were further investigated. The effect of current on SO2 purification rate was first increased and then decreased, while the purification rate of NOx increased with the increase of current; The removal efficiency of SO2 and NOx is better under oxygen-free and hypoxia conditions; The effect of Fe(II) content on SO2 purification rate was not significant, but on NOx purification was significant. The purification rate of NOx increased significantly after adding 0.1 mol/L Fe(II) into the system, but decreased continuously afterwards with the increase of Fe(II) content. Finally, the reaction mechanism of simultaneous desulfurization and denitrification was analyzed, and the transformation process of sulfur and nitrate in the system was discussed.