Enhancement of degradation of herbicide atrazine through efficient manganese-porphyrins: Mechanistic insights, degradation products, and toxicity assessment

Abstract

The herbicide atrazine (ATZ) is widely used in weed control, especially in Brazil. Its persistence and toxicity raise environmental and health concerns and may cause several problems. In this context, manganese porphyrins emerge as promising catalysts for ATZ degradation, mimicking the action of cytochrome P450. This study evaluated the catalytic potential of five manganese porphyrins in the degradation of ATZ under mild conditions. Different oxidants were tested, including Oxone®, H₂O₂, iodosylbenzene, and iodobenzene diacetate. The effect of axial ligands as cocatalysts was also investigated. The best results were obtained for third-generation porphyrins and the iodoarenes oxidants, achieving up to 85% of ATZ degradation, the best result for Mn-porphyrins so far. Axial ligands did not bring improvements to the catalytic systems while assessments with radical inhibitors indicated the participation of reactive species, such as Mn^V-oxo, ·OH, and ¹O₂. Mass spectrometry analysis confirmed the formation of the main ATZ metabolites, mostly desisopropylatrazine, and the formation of 6-acetamidoatrazine which is observed for the first time for manganese porphyrins catalyzed systems.