The Degradation of Nitric Oxide (NO) Using Fenton Process: A Review

Abstract

NO removal using by homogeneous Fenton, heterogeneous Fenton and UV-Fenton processes are discussed in this paper, and the advantages and disadvantages of these methods are analyzed. It is found that Homogeneous Fenton process could achieve 90% NO removal efficiency, but is confined to a narrow pH window (2.5–4.0) and generates substantial iron sludge. Heterogeneous Fenton process extends the optimal pH to 3–7, maintains high efficiency, and minimizes secondary pollution. NO removal efficiency could be up to 80% in the UV-Fenton process by enhancing the regeneration of catalytically active species, yet this improvement is compromised by low photon utilization efficiency. The NO removal mechanisms across various Fenton processes, and critical parameters influencing denitrification efficiency like pH, catalyst dosage, operating temperature, H₂O₂ concentration, and NO concentration are also discussed. Furthermore, the simultaneous absorption of coexisting flue gas pollutants via Fenton-based systems is critically evaluated. Finally, major bottlenecks—H₂O₂ consumption, catalyst stability, and photon utilization—are pinpointed, with targeted strategies proposed including AOPs coupling and composite catalyst development. This review provides a mechanistic framework and practical guidance for designing retrofittable, cost-effective Fenton-based systems for simultaneous flue gas purification.