Utilizing l-Ascorbic Acid to Inhibit Adverse Oxidation and Enhance Denitration Efficiency during Sulfite Solution Absorption of NO2: Mechanism and Process Parameters

In the typical wet flue gas denitration technology using sulfite solutions, the rapid free radical chain reaction of SO3•– oxidation by O2 is the main reason for the significant consumption of absorbents and inefficient denitration. The study utilizes l-ascorbic acid (VC) to inhibit the free radical chain reaction. VC combined with SO3•– to form stable compounds, which hindered the oxidation of SO3•– to SO5•– by O2, leading to an 80.7 mol % decrease in Na2SO3 consumption by adding millimolar-level VC. Compared to the sulfite solution, the best denitration efficiency of the VC/Na2SO3 mixture solution increased from 94.4 to 99.2 vol %, and the absorption time for absorption efficiency above 90 vol % was extended from 7 to 72 min. Additionally, a macro absorption model describing the rates of macro absorption was established based on various operating conditions.