Novel EDTA modified steel slag-based catalyst for NO removal through heterogeneous Fenton processes

The limitation of monofunctional active sites has become a critical bottleneck in heterogeneous Fenton-based denitrification systems. For this purpose, in view of the structural characteristics of steel slag and the chemical properties of EDTA, EDTA was utilized to modify the steel slag to prepare catalyst EDTA-SA-SS with multi-functional active centers, which was catalyze H₂O₂ to oxidize and remove NO. The results demonstrated that catalyst EDTA-SA-SS exhibited the excellent catalytic efficiency with 91.6 % and good stability on NO removal. The superior Fenton catalytic activity of the EDTA-SA-SS system arises from its integrated reaction mechanisms: (1) EDTA acts both electron-donating and electron-shuttling roles during Fenton reactions, leveraging its phenolic hydroxyl and carboxyl groups to facilitate Fe(III) reduction. EDTA can lower the redox potential of Fe(II)/Fe(III) as a result of the constructed C-O-Fe bonding. Therefore, by regulating the electronic structure of Fe through EDTA, the circulation of Fe(II)/Fe(III) can be enhanced, and hydroxyl radicals (•OH) can be continuously generated to promote the oxidation reaction of NO. (2) Concurrently, continuously regenerated Fe(II)EDTA complexes chelate NO, forming a synergistic oxidation-complexation removal pathway. Furthermore, NO removal performance and kinetic data by EDTA-SA-SS/H₂O₂ system with various operational settings were examined. This research introduces an eco-friendly and resource-efficient Fenton denitrification approach for flue gas treatment.