Enhanced oxidative removal of NO by UV/in situ Fenton: Factors, kinetics and simulation

Peng Yuan; Zhi Wang; Muhammad Sajjad Ahmad; Wenwen Kong; Jiao Ma; Zhuozhi Wang; Boxiong Shen; Zhiyong Ji

doi:10.1016/j.scitotenv.2021.146202

Enhanced oxidative removal of NO by UV/in situ Fenton: Factors, kinetics and simulation

Sci Total Environ. 2021 Jul 15:778:146202. doi: 10.1016/j.scitotenv.2021.146202. Epub 2021 Mar 3.

Authors

Peng Yuan¹, Zhi Wang², Muhammad Sajjad Ahmad², Wenwen Kong², Jiao Ma², Zhuozhi Wang², Boxiong Shen³, Zhiyong Ji⁴

Affiliations

¹ Tianjin Key Laboratory of Clean Energy Utilization and Pollutants Control, School of Energy & Environmental Engineering, Hebei University of Technology, Tianjin 300401, PR China; School of Chemical Engineering & Technology, Hebei University of Technology, Tianjin 300130, PR China.
² Tianjin Key Laboratory of Clean Energy Utilization and Pollutants Control, School of Energy & Environmental Engineering, Hebei University of Technology, Tianjin 300401, PR China.
³ Tianjin Key Laboratory of Clean Energy Utilization and Pollutants Control, School of Energy & Environmental Engineering, Hebei University of Technology, Tianjin 300401, PR China. Electronic address: shenbx@hebut.edu.cn.
⁴ School of Chemical Engineering & Technology, Hebei University of Technology, Tianjin 300130, PR China. Electronic address: jizhiyong@hebut.edu.cn.

PMID: 34030361
DOI: 10.1016/j.scitotenv.2021.146202

Abstract

A series of experiments on the oxidative removal of NO from flue gas using a novel in situ Fenton (IF) system was performed in the presence of ultraviolet light (UV). The comparison tests revealed that the in situ Fenton system facilitated by UV (UV/IF) has a better oxidation ability of NO than that of the IF system due to the photochemical effect on the generation of oxidative species like (OH). Both of the aforementioned oxidation efficiencies were higher than that of the conventional Fenton system (CF) depending on the premix of Fe²⁺ and H₂O₂ solutions, which attribute to the improvement of (OH) yield and valid utilization with continuous addition of fresh reagents and UV radiation. In follow-up experiments, the effects of UV power, gas flow rate, reagent temperature, Fe²⁺/H₂O₂ molar ratio, initial pH, initial concentration of NO and SO₂ and volume fraction O₂ and CO₂ on the oxidative removal of NO by UV/IF method were investigated respectively. Moreover, the results of kinetic analysis indicated that NO oxidation was confirmed to have a pseudo-first-order kinetics pattern. The rate constants decreased slightly with increasing liquid temperature, and then the apparent activation energy of NO oxidation reactions in the UV/IF system was calculated as -5.62 kJ/mol by the Arrhenius equation. Furthermore, the reaction mechanism and application prospects concerning NO oxidative removal by using the UV/IF system was speculated in brief. Finally, the computational fluid dynamics (CFD) simulations revealed that the improvement of axial and radial gas hold-up would enhance the gas-liquid contact and accelerate the oxidation reactions on the interface. In addition to reasonable control of process parameters, the optimization of reactor interior structure needs to be carried out via CFD simulation and experimental validation in future research, both are favourable to promote the NO oxidation efficiency and large-scale development of this technology.

Keywords: CFD; Denitration; Fenton; Oxidation; Ultraviolet.