NO<i>_x</i> Absorption Enhancement and Sulfite Oxidation Inhibition via a Match Strategy in Na₂SO₃ Solution from a Wet Flue Gas Denitration System

Abstract

Excessive oxidation of sulfite can lead to low utilization efficiency and inhibit its application in the wet flue gas denitration process. Using organic absorbent can retard the sulfite oxidation rate but may cause secondary pollution due to the formation of byproducts. A match strategy between sodium thiosulfate (Na2S2O3) and organic additives was proposed to minimize the demand of organic absorbent and enhance the NOx removal efficiency. The results showed that Na2S2O3 and hydroquinone (HQ) exhibited a positive synergistic effect. The enhancement effects (E and e) indicated that the absorption capacity of NOx increased more than 2 times when the amounts of Na2S2O3 and HQ were higher than 0.1% and 0.5%. The optimal match ratio of Na2S2O3 to HQ was 10:1 with a Na2S2O3 concentration of 1%. Compared with the use of single organic additives, this optimized match reduced about 60% of organic additives. The research on the interaction mechanism suggested that the synergistic effect was related to the redox reaction between additives, and the intermediate formed by hydroquinone can be reduced by Na2S2O3 to achieve better oxidation resistance. This match strategy exhibited a positive synergy effect and can be applied as an effective way to enhance the NOx removal efficiency.