Removal of NO in flue gas simulated by the Fe²⁺/Cu²⁺-activated double oxidant system

ABSTRACT

$\cdot \mathrm{O}\mathrm{H}$The wet denitrification technology has a good development prospect due to its simple system and mild reaction conditions, and related research has become a hot topic in the field of flue gas purification. In this work, a novel simultaneous removal technology of NO from flue gas using Fe²⁺/Cu²⁺-catalytic H₂O₂/(NH₄)₂S₂O₈ system was developed for the first time. The feasibility of this new flue gas cleaning technology was explored through a series of experiments and performance analyses. The mechanism of oxidation products, free radicals and simultaneous removal of NO was revealed. The effects of the main process parameters on the removal of NO were investigated. Relevant results demonstrated that the removal efficiency of NO was elevated when the concentration of (NH₄)₂S₂O₈ or reacting temperature increased, while it was decreased after increasing the raising of Fe²⁺, Cu²⁺ and H₂O₂ concentrations. The main radicals were and·${\mathrm{S}\mathrm{O}}_4^{-}$, using the electron spin resonance technique in the solution, and played a very important role in NO removal. The main products were carried out by ion chromatography and elemental N material accountancy, and the results showed that it was sulfate and nitrate in the solution, which provided theoretical guidance for the subsequent treatment and resource utilization of the absorption solution. The results of the study provided a theoretical basis for the industrial application of wet denitrification.

Highlights

1. A new green process of NO removal by a wet process with Fe²⁺/Cu²⁺ activated (NH₄)₂S₂O₈ system is proposed in this paper;

2. Elimination mechanisms and paths of NO are elucidated;

3. The synergistic role produced by Cu²⁺ and Fe²⁺ is beneficial to the purification of NO;

4. The synergistic role produced by (NH₄)₂S₂O₈ and H₂O₂ increased the concentration of free radicals in the solution;

5. This process jointly considers the enhanced removal of NO and recycling of transition metal ions.

GRAPHICAL ABSTRACT

KEYWORDS:

• Nitric oxide (NO) elimination
• flue gas
• sulphate and hydroxyl radical
• fenton-like
• synergistic catalysis of Cu²⁺/Fe²⁺

Disclosure statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Data availability statement

The authors confirm that the data supporting the findings of this study are available within the article and its supplementary materials.

Additional information

Funding

This work was supported by the National Natural Science Foundation of China International (Regional) Cooperation and Exchange Project [grant number 21961160740] and the Shanxi Province Applied Basic Research Program [grant number 201901D111178].