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

Abstract

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.