Utilizing l‑Ascorbic Acid to Inhibit\nAdverse Oxidation and Enhance Denitration Efficiency during Sulfite\nSolution Absorption of NO<sub>2</sub>: Mechanism and Process Parameters

In the typical wet flue gas denitration technology using\nsulfite\nsolutions, the rapid free radical chain reaction of SO<sub>3</sub><sup>•–</sup> oxidation by O<sub>2</sub> is the main\nreason for the significant consumption of absorbents and inefficient\ndenitration. The study utilizes l-ascorbic acid (VC) to inhibit\nthe free radical chain reaction. VC combined with SO<sub>3</sub><sup>•–</sup> to form stable compounds, which hindered the\noxidation of SO<sub>3</sub><sup>•–</sup> to SO<sub>5</sub><sup>•–</sup> by O<sub>2</sub>, leading to an 80.7\nmol % decrease in Na<sub>2</sub>SO<sub>3</sub> consumption by adding\nmillimolar-level VC. Compared to the sulfite solution, the best denitration\nefficiency of the VC/Na<sub>2</sub>SO<sub>3</sub> mixture solution\nincreased from 94.4 to 99.2 vol %, and the absorption time for absorption\nefficiency above 90 vol % was extended from 7 to 72 min. Additionally,\na macro absorption model describing the rates of macro absorption\nwas established based on various operating conditions.