Degradation of Nitrogen‐Heterocyclic Compounds by Anodic Oxidation and Electro‐Fenton Methods

This study describes the degradation of nitrogen‐heterocyclic compounds (NHCs) by anodic oxidation and electro‐Fenton. Using indole as a model nitrogen‐heterocyclic compound, the removal of indole reached 68% and 97% by anodic oxidation and electro‐Fenton, respectively, while the decay of TOC was 15% and 38% correspondingly. By the analysis of ultraviolet‐visible spectra and liquid chromatography/mass spectrum, the degradation mechanism of indole by electro‐Fenton was proposed as hydroxyl oxidation and anodic oxidation. The degradation of other NHCs including quinoline, isoquinoline and pyridine by anodic oxidation and electro‐Fenton revealed the same sequence: quinoline ≈ isoquinoline > indole ≫ pyridine. A significant correlation between ln k (natural logarithm of rate constants) and E LUMO (the energy of the lowest unoccupied molecular orbit) was obtained by quantitative structure‐activity relationship analysis. Degradation of coking plant wastewater showed the removal of COD and TOC were 42% and 22% respectively after 180 min treatment by electro‐Fenton.